A systematic review: Performance of RDTs for the detection of Plasmodium knowlesi, Plasmodium malariae, and Plasmodium ovale mono-infections in human blood.

PubMed

Yerlikaya, Seda; Campillo, Ana; Gonzalez, Iveth J

2018-03-15

Despite the increased use and worldwide distribution of malaria rapid diagnostic tests (RDTs) which distinguish between Plasmodium falciparum and non-falciparum species, little is known about their performance for detecting Plasmodium knowlesi (Pk), Plasmodium malariae (Pm), and Plasmodium ovale (Po). The objective of this review is to analyze results of published studies evaluating the diagnostic accuracy of malaria RDTs in detecting Pk, Pm and Po mono-infections.MEDLINE, EMBASE, Web of Science and CENTRAL databases were systematically searched to identify studies which reported on the performance of RDTs in detecting Pk, Pm,Po mono-infections.Among 40 studies included in the review, three reported on Pk, eight on Pm, five on Po, one on Pk and Pm, and 23 on Pm and Po infections. In the meta-analysis, estimates of sensitivities of RDTs in detecting Pk infections ranged from 2% to 48%. Test performances for Pm and Po infections were less accurate and highly heterogeneous, mainly due to the small number of samples tested.Limited data available suggest that malaria RDTs show suboptimal performance for detecting Pk, Pm,Po infections. New improved RDTs as well as appropriately designed, cross-sectional studies to demonstrate their usefulness in the detection of neglected Plasmodium species, are urgently needed.

In Vitro Alterations Do Not Reflect a Requirement for Host Cell Cycle Progression during Plasmodium Liver Stage Infection

PubMed Central

Hanson, Kirsten K.; March, Sandra; Ng, Shengyong; Bhatia, Sangeeta N.

2014-01-01

Prior to invading nonreplicative erythrocytes, Plasmodium parasites undergo their first obligate step in the mammalian host inside hepatocytes, where each sporozoite replicates to generate thousands of merozoites. While normally quiescent, hepatocytes retain proliferative capacity and can readily reenter the cell cycle in response to diverse stimuli. Many intracellular pathogens, including protozoan parasites, manipulate the cell cycle progression of their host cells for their own benefit, but it is not known whether the hepatocyte cell cycle plays a role during Plasmodium liver stage infection. Here, we show that Plasmodium parasites can be observed in mitotic hepatoma cells throughout liver stage development, where they initially reduce the likelihood of mitosis and ultimately lead to significant acquisition of a binucleate phenotype. However, hepatoma cells pharmacologically arrested in S phase still support robust and complete Plasmodium liver stage development, which thus does not require cell cycle progression in the infected cell in vitro. Furthermore, murine hepatocytes remain quiescent throughout in vivo infection with either Plasmodium berghei or Plasmodium yoelii, as do Plasmodium falciparum-infected primary human hepatocytes, demonstrating that the rapid and prodigious growth of liver stage parasites is accomplished independent of host hepatocyte cell cycle progression during natural infection. PMID:25416236

Prevalence and distribution of human Plasmodium infection in Pakistan.

PubMed

Khattak, Aamer A; Venkatesan, Meera; Nadeem, Muhammad F; Satti, Humayoon S; Yaqoob, Adnan; Strauss, Kathy; Khatoon, Lubna; Malik, Salman A; Plowe, Christopher V

2013-08-28

Both Plasmodium vivax and Plasmodium falciparum are prevalent in Pakistan, yet up-to-date data on the epidemiology of malaria in Pakistan are not available. This study was undertaken to determine the current prevalence and distribution of Plasmodium species across the country. A malariometric population survey was conducted in 2011 using blood samples collected from 801 febrile patients of all ages in four provinces and the capital city of Islamabad. Microscopically confirmed Plasmodium-positive blood samples were reconfirmed by polymerase chain reaction (PCR). Confirmed parasite-positive samples were subjected to species-specific PCR capable of detecting four species of human malaria. Of the 707 PCR-positive samples, 128 (18%) were P. falciparum, 536 (76%) were P. vivax, and 43 (6%) were mixed P. falciparum and P. vivax. Ninety-four microscopy-positive samples were PCR-negative, and Plasmodium malariae and Plasmodium ovale were not detected. Prevalence of P. vivax ranged from 2.4% in Punjab Province to 10.8% in Sindh Province and prevalence of P. falciparum ranged from 0.1% in Islamabad to 3.8% in Balochistan. Plasmodium infections in Pakistan are largely attributed to P. vivax but P. falciparum and mixed species infections are also prevalent. In addition, regional variation in the prevalence and species composition of malaria is high.

Prevalence and distribution of human Plasmodium infection in Pakistan

PubMed Central

2013-01-01

Background Both Plasmodium vivax and Plasmodium falciparum are prevalent in Pakistan, yet up-to-date data on the epidemiology of malaria in Pakistan are not available. This study was undertaken to determine the current prevalence and distribution of Plasmodium species across the country. Methods A malariometric population survey was conducted in 2011 using blood samples collected from 801 febrile patients of all ages in four provinces and the capital city of Islamabad. Microscopically confirmed Plasmodium-positive blood samples were reconfirmed by polymerase chain reaction (PCR). Confirmed parasite-positive samples were subjected to species-specific PCR capable of detecting four species of human malaria. Results Of the 707 PCR-positive samples, 128 (18%) were P. falciparum, 536 (76%) were P. vivax, and 43 (6%) were mixed P. falciparum and P. vivax. Ninety-four microscopy-positive samples were PCR-negative, and Plasmodium malariae and Plasmodium ovale were not detected. Prevalence of P. vivax ranged from 2.4% in Punjab Province to 10.8% in Sindh Province and prevalence of P. falciparum ranged from 0.1% in Islamabad to 3.8% in Balochistan. Conclusions Plasmodium infections in Pakistan are largely attributed to P. vivax but P. falciparum and mixed species infections are also prevalent. In addition, regional variation in the prevalence and species composition of malaria is high. PMID:23984968

Highly Dynamic Host Actin Reorganization around Developing Plasmodium Inside Hepatocytes

PubMed Central

Gomes-Santos, Carina S. S.; Itoe, Maurice A.; Afonso, Cristina; Henriques, Ricardo; Gardner, Rui; Sepúlveda, Nuno; Simões, Pedro D.; Raquel, Helena; Almeida, António Paulo; Moita, Luis F.; Frischknecht, Friedrich; Mota, Maria M.

2012-01-01

Plasmodium sporozoites are transmitted by Anopheles mosquitoes and infect hepatocytes, where a single sporozoite replicates into thousands of merozoites inside a parasitophorous vacuole. The nature of the Plasmodium-host cell interface, as well as the interactions occurring between these two organisms, remains largely unknown. Here we show that highly dynamic hepatocyte actin reorganization events occur around developing Plasmodium berghei parasites inside human hepatoma cells. Actin reorganization is most prominent between 10 to 16 hours post infection and depends on the actin severing and capping protein, gelsolin. Live cell imaging studies also suggest that the hepatocyte cytoskeleton may contribute to parasite elimination during Plasmodium development in the liver. PMID:22238609

No impact of strongylid infections on the detection of Plasmodium spp. in faeces of western lowland gorillas and eastern chimpanzees.

PubMed

Mapua, Mwanahamisi I; Pafčo, Barbora; Burgunder, Jade; Profousová-Pšenková, Ilona; Todd, Angelique; Hashimoto, Chie; Qablan, Moneeb A; Modrý, David; Petrželková, Klára J

2017-04-26

Although a high genetic diversity of Plasmodium spp. circulating in great apes has been revealed recently due to non-invasive methods enabling detection in faecal samples, little is known about the actual mechanisms underlying the presence of Plasmodium DNA in faeces. Great apes are commonly infected by strongylid nematodes, including hookworms, which cause intestinal bleeding. The impact of strongylid infections on the detection of Plasmodium DNA in faeces was assessed in wild, western, lowland gorillas from Dzanga Sangha Protected Areas, Central African Republic and eastern chimpanzees from Kalinzu Forest Reserve, Uganda. Fifty-one faecal samples from 22 habituated gorillas and 74 samples from 15 habituated chimpanzees were analysed using Cytochrome-b PCR assay and coprological methods. Overall, 26.4% of the analysed samples were positive for both Plasmodium spp. and strongylids. However, the results showed no significant impact of intensity of infections of strongylids on detection of Plasmodium DNA in gorilla and chimpanzee faeces. Bleeding caused by strongylid nematode Necator spp. cannot explain the presence of Plasmodium DNA in ape faeces.

Slime mold solves maze in one pass, assisted by gradient of chemo-attractants.

PubMed

Adamatzky, Andrew

2012-06-01

Plasmodium of Physarum polycephalum is a large cell, visible by unaided eye, which exhibits sophisticated patterns of foraging behaviour. The plasmodium's behaviour is well interpreted in terms of computation, where data are spatially extended configurations of nutrients and obstacles, and results of computation are networks of protoplasmic tubes formed by the plasmodium. In laboratory experiments and numerical simulation we show that if plasmodium of P. polycephalum is inoculated in a maze's peripheral channel and an oat flake (source of attractants) in a the maze's central chamber then the plasmodium grows toward target oat flake and connects the flake with the site of original inoculation with a pronounced protoplasmic tube. The protoplasmic tube represents a path in the maze. The plasmodium solves maze in one pass because it is assisted by a gradient of chemo-attractants propagating from the target oat flake.

Construction of living cellular automata using the Physarum plasmodium

NASA Astrophysics Data System (ADS)

Shirakawa, Tomohiro; Sato, Hiroshi; Ishiguro, Shinji

2015-04-01

The plasmodium of Physarum polycephalum is a unicellular and multinuclear giant amoeba that has an amorphous cell body. To clearly observe how the plasmodium makes decisions in its motile and exploratory behaviours, we developed a new experimental system to pseudo-discretize the motility of the organism. In our experimental space that has agar surfaces arranged in a two-dimensional lattice, the continuous and omnidirectional movement of the plasmodium was limited to the stepwise one, and the direction of the locomotion was also limited to four neighbours. In such an experimental system, a cellular automata-like system was constructed using the living cell. We further analysed the exploratory behaviours of the plasmodium by duplicating the experimental results in the simulation models of cellular automata. As a result, it was revealed that the behaviours of the plasmodium are not reproduced by only local state transition rules; and for the reproduction, a kind of historical rule setting is needed.

Gene disruption reveals a dispensable role for plasmepsin VII in the Plasmodium berghei life cycle.

PubMed

Mastan, Babu S; Kumari, Anchala; Gupta, Dinesh; Mishra, Satish; Kumar, Kota Arun

2014-06-01

Plasmepsins (PM), aspartic proteases of Plasmodium, comprises a family of ten proteins that perform critical functions in Plasmodium life cycle. Except VII and VIII, functions of the remaining plasmepsin members have been well characterized. Here, we have generated a mutant parasite lacking PM VII in Plasmodium berghei using reverse genetics approach. Systematic comparison of growth kinetics and infection in both mosquito and vertebrate host revealed that PM VII depleted mutants exhibited no defects in development and progressed normally throughout the parasite life cycle. These studies suggest a dispensable role for PM VII in Plasmodium berghei life cycle. Copyright © 2014 Elsevier B.V. All rights reserved.

Diagnostic challenges and case management of the first imported case of Plasmodium knowlesi in Sri Lanka.

PubMed

Dewanee Ranaweera, A; Danansuriya, Manjula N; Pahalagedera, Kusumawathie; de A W Gunasekera, W M Kumudunayana T; Dharmawardena, Priyani; Mak, Keng Wai; Wong, Pei-Sze Jeslyn; Li, Mei-Zhi Irene; Tan, Cheong Huat; Hapuarachchi, Hapuarachchige C; Herath, Hema D B; Fernando, Deepika

2017-03-21

Sri Lanka has achieved 'malaria-free' status and is now in the phase of prevention of re-introduction of malaria. Imported malaria remains a challenge to resurgence of the disease. The diagnostic challenges encountered and the rapid response initiated to manage a Plasmodium infection, which was later confirmed as Plasmodium knowlesi, the first reported case from Sri Lanka, is discussed. An army officer who returned from Malaysia in October 2016 was found to be positive for Plasmodium both by microscopy and rapid diagnostic test (RDT) by the Anti Malaria Campaign Sri Lanka (AMC) during his third visit to a health care provider. Microscopy findings were suspicious of P. knowlesi infection as the smears showed parasite stages similar to both Plasmodium malariae and Plasmodium falciparum. Nested PCR at AMC confirmed Plasmodium genus, but not the species. In the absence of species confirmation, the patient was treated as a case of P. falciparum. The presence of P. knowlesi was later confirmed by a semi-nested PCR assay performed at the Environmental Health Institute, National Environmental Agency in Singapore. The parasite strain was also characterized by sequencing the circumsporozoite gene. Extensive case investigation including parasitological and entomological surveillance was carried out. Plasmodium knowlesi should be suspected in patients returning from countries in the South Asian region where the parasite is prevalent and when blood smear results are inconclusive.

Plasmodium infection, anaemia and mosquito net use among school children across different settings in Kenya.

PubMed

Gitonga, Caroline W; Edwards, Tansy; Karanja, Peris N; Noor, Abdisalan M; Snow, Robert W; Brooker, Simon J

2012-07-01

To investigate risk factors, including reported net use, for Plasmodium infection and anaemia among school children and to explore variations in effects across different malaria ecologies occurring in Kenya. This study analysed data for 49 975 school children in 480 schools surveyed during a national school malaria survey, 2008-2010. Mixed effects logistic regression was used to investigate factors associated with Plasmodium infection and anaemia within different malaria transmission zones. Insecticide-treated net (ITN) use was associated with reduction in the odds of Plasmodium infection in coastal and western highlands epidemic zones and among boys in the lakeside high transmission zone. Other risk factors for Plasmodium infection and for anaemia also varied by zone. Plasmodium infection was negatively associated with increasing socio-economic status in all transmission settings, except in the semi-arid north-east zone. Plasmodium infection was a risk factor for anaemia in lakeside high transmission, western highlands epidemic and central low-risk zones, whereas ITN use was only associated with lower levels of anaemia in coastal and central zones and among boys in the lakeside high transmission zone. The risk factors for Plasmodium infection and anaemia, including the protective associations with ITN use, vary according to malaria transmission settings in Kenya, and future efforts to control malaria and anaemia should take into account such heterogeneities among school children. © 2012 Blackwell Publishing Ltd.

Morphologic and molecular study of hemoparasites in wild corvids and evidence of sequence identity with Plasmodium DNA detected in captive black-footed penguins (Spheniscus demersus).

PubMed

Leclerc, Antoine; Chavatte, Jean-Marc; Landau, Irène; Snounou, Georges; Petit, Thierry

2014-09-01

A morphologic and molecular epidemiologic investigation was conducted on a captive African black-footed penguin (Spheniscus demersus) colony with a history of Plasmodium infections at La Palmyre Zoo (France). Each penguin received 12.5 mg of pyrimethamine twice a week as a prophylaxis every year from April to November. Although Plasmodium parasites were not detected in blood smears and tissues collected from the penguins, various blood parasites were recorded in blood smears from wild Eurasian magpies (Pica pica) and carrion crows (Corvus corone) sampled at the same time in the study area. These parasites consisted of several Plasmodium spp. (P. lenoblei, P. dorsti, P bioccai, P. relictum, P. dherteae, P. beaucournui, P. maior, P. tranieri, and P. snounoui), Parahaemoproteus spp., Trypanosoma spp., and Leucocytozoon spp. On the other hand, nested polymerase chain reaction enabled detection of Plasmodium DNA in 28/44 (64%) penguins, 15/25 (60%) magpies, and 4/9 (44%) crows. Sequencing and phylogenetic analyses indicated that the parasite DNA amplified from the penguins, magpies, and crows were similar. Magpies and crows could therefore act as a reservoir for penguin Plasmodium infections, which may be more prevalent than previously thought. Morphologic characterization of the Plasmodium spp. detected in the penguins, as well as further biological and epidemiologic studies, are needed to fully understand the transmission of Plasmodium parasites to captive penguins.

Molecular evidence of high rates of asymptomatic P. vivax infection and very low P. falciparum malaria in Botswana.

PubMed

Motshoge, Thato; Ababio, Grace K; Aleksenko, Larysa; Read, John; Peloewetse, Elias; Loeto, Mazhani; Mosweunyane, Tjantilili; Moakofhi, Kentse; Ntebele, Davies S; Chihanga, Simon; Motlaleng, Mpho; Chinorumba, Anderson; Vurayai, Moses; Pernica, Jeffrey M; Paganotti, Giacomo M; Quaye, Isaac K

2016-09-29

Botswana is one of eight SADC countries targeting malaria elimination by 2018. Through spirited upscaling of control activities and passive surveillance, significant reductions in case incidence of Plasmodium falciparum (0.96 - 0.01) was achieved between 2008 and 2012. As part of the elimination campaign, active detection of asymptomatic Plasmodium species by a highly sensitive method was deemed necessary. This study was carried out to determine asymptomatic Plasmodium species carriage by nested PCR in the country, in 2012. A cross-sectional study involving 3924 apparently healthy participants were screened for Plasmodium species in 14 districts (5 endemic: Okavango, Ngami, Tutume, Boteti and Bobirwa; and 9 epidemic: North East, Francistown, Serowe-Palapye, Ghanzi, Kweneng West, Kweneng East, Kgatleng, South East, and Good Hope). Venous blood was taken from each participant for a nested PCR detection of Plasmodium species. The parasite rates of asymptomatic Plasmodium species detected were as follows: Plasmodium falciparum, 0.16 %; Plasmodium vivax, 4.66 %; Plasmodium malariae, (Pm) 0.16 %; Plasmodium ovale, 0 %, mixed infections (P. falciparum and P. vivax), 0.055 %; and (P. vivax and P. malariae), 0.027 %, (total: 5.062 %). The high proportion of asymptomatic reservoir of P. vivax was clustered in the East, South Eastern and Central districts of the country. There appeared to be a correlation between the occurrence of P. malariae infection with P. vivax infection, with the former only occurring in districts that had substantial P. vivax circulation. The median age among 2-12 year olds for P. vivax infection was 5 years (Mean 5.13 years, interquartile range 3-7 years). The odds of being infected with P. vivax decreased by 7 % for each year increase in age (OR 0.93, 95 % CI 0.87-1.00, p = 0.056). We have confirmed low parasite rate of asymptomatic Plasmodium species in Botswana, with the exception of P.vivax which was unexpectedly high. This has implication for the elimination campaign so a follow up study is warranted to inform decisions on new strategies that take this evidence into account in the elimination campaign.

First case of a naturally acquired human infection with Plasmodium cynomolgi

PubMed Central

2014-01-01

Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans. The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods. Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax. This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax. Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its implication on human public health and in the control of human malaria. The zoonotic malaria cannot be ignored in view of increasing interactions between man and wild animals in the process of urbanization. PMID:24564912

First case of a naturally acquired human infection with Plasmodium cynomolgi.

PubMed

Ta, Thuy H; Hisam, Shamilah; Lanza, Marta; Jiram, Adela I; Ismail, NorParina; Rubio, José M

2014-02-24

Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans.The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods.Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax.This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax.Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its implication on human public health and in the control of human malaria.The zoonotic malaria cannot be ignored in view of increasing interactions between man and wild animals in the process of urbanization.

Evaluation of the sensitivity of a pLDH-based and an aldolase-based rapid diagnostic test for diagnosis of uncomplicated and severe malaria caused by PCR-confirmed Plasmodium knowlesi, Plasmodium falciparum, and Plasmodium vivax.

PubMed

Barber, Bridget E; William, Timothy; Grigg, Matthew J; Piera, Kim; Yeo, Tsin W; Anstey, Nicholas M

2013-04-01

Plasmodium knowlesi can cause severe and fatal human malaria in Southeast Asia. Rapid diagnosis of all Plasmodium species is essential for initiation of effective treatment. Rapid diagnostic tests (RDTs) are sensitive for detection of uncomplicated and severe falciparum malaria but have not been systematically evaluated in knowlesi malaria. At a tertiary referral hospital in Sabah, Malaysia, we prospectively evaluated the sensitivity of two combination RDTs for the diagnosis of uncomplicated and severe malaria from all three potentially fatal Plasmodium species, using a pan-Plasmodium lactate dehydrogenase (pLDH)-P. falciparum histidine-rich protein 2 (PfHRP2) RDT (First Response) and a pan-Plasmodium aldolase-PfHRP2 RDT (ParaHIT). Among 293 hospitalized adults with PCR-confirmed Plasmodium monoinfection, the sensitivity of the pLDH component of the pLDH-PfHRP2 RDT was 74% (95/129; 95% confidence interval [CI], 65 to 80%), 91% (110/121; 95% CI, 84 to 95%), and 95% (41/43; 95% CI, 85 to 99%) for PCR-confirmed P. knowlesi, P. falciparum, and P. vivax infections, respectively, and 88% (30/34; 95% CI, 73 to 95%), 90% (38/42; 95% CI, 78 to 96%), and 100% (12/12; 95% CI, 76 to 100%) among patients tested before antimalarial treatment was begun. Sensitivity in severe malaria was 95% (36/38; 95% CI, 83 to 99), 100% (13/13; 95% CI, 77 to 100), and 100% (7/7; 95% CI, 65 to 100%), respectively. The aldolase component of the aldolase-PfHRP2 RDT performed poorly in all Plasmodium species. The pLDH-based RDT was highly sensitive for the diagnosis of severe malaria from all species; however, neither the pLDH- nor aldolase-based RDT demonstrated sufficiently high overall sensitivity for P. knowlesi. More sensitive RDTs are needed in regions of P. knowlesi endemicity.

Checks and balances? DNA replication and the cell cycle in Plasmodium.

PubMed

Matthews, Holly; Duffy, Craig W; Merrick, Catherine J

2018-03-27

It is over 100 years since the life-cycle of the malaria parasite Plasmodium was discovered, yet its intricacies remain incompletely understood - a knowledge gap that may prove crucial for our efforts to control the disease. Phenotypic screens have partially filled the void in the antimalarial drug market, but as compound libraries eventually become exhausted, new medicines will only come from directed drug development based on a better understanding of fundamental parasite biology. This review focusses on the unusual cell cycles of Plasmodium, which may present a rich source of novel drug targets as well as a topic of fundamental biological interest. Plasmodium does not grow by conventional binary fission, but rather by several syncytial modes of replication including schizogony and sporogony. Here, we collate what is known about the various cell cycle events and their regulators throughout the Plasmodium life-cycle, highlighting the differences between Plasmodium, model organisms and other apicomplexan parasites and identifying areas where further study is required. The possibility of DNA replication and the cell cycle as a drug target is also explored. Finally the use of existing tools, emerging technologies, their limitations and future directions to elucidate the peculiarities of the Plasmodium cell cycle are discussed.

Avian malaria, ecological host traits and mosquito abundance in southeastern Amazonia.

PubMed

Fecchio, Alan; Ellis, Vincenzo A; Bell, Jeffrey A; Andretti, Christian B; D'Horta, Fernando M; Silva, Allan M; Tkach, Vasyl V; Weckstein, Jason D

2017-07-01

Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies suggest that variation in its prevalence across avian hosts is correlated with a variety of ecological traits. Here we examine the relationship between prevalence and diversity of Plasmodium lineages in southeastern Amazonia and: (1) host ecological traits (nest location, nest type, flocking behaviour and diet); (2) density and diversity of avian hosts; (3) abundance and diversity of mosquitoes; and (4) season. We used molecular methods to detect Plasmodium in blood samples from 675 individual birds of 120 species. Based on cytochrome b sequences, we recovered 89 lineages of Plasmodium from 136 infected individuals sampled across seven localities. Plasmodium prevalence was homogeneous over time (dry season and flooding season) and space, but heterogeneous among 51 avian host species. Variation in prevalence among bird species was not explained by avian ecological traits, density of avian hosts, or mosquito abundance. However, Plasmodium lineage diversity was positively correlated with mosquito abundance. Interestingly, our results suggest that avian host traits are less important determinants of Plasmodium prevalence and diversity in southeastern Amazonia than in other regions in which they have been investigated.

Plasmodium falciparum-like parasites infecting wild apes in southern Cameroon do not represent a recurrent source of human malaria

PubMed Central

Sundararaman, Sesh A.; Liu, Weimin; Keele, Brandon F.; Learn, Gerald H.; Bittinger, Kyle; Mouacha, Fatima; Ahuka-Mundeke, Steve; Manske, Magnus; Sherrill-Mix, Scott; Li, Yingying; Malenke, Jordan A.; Delaporte, Eric; Laurent, Christian; Mpoudi Ngole, Eitel; Kwiatkowski, Dominic P.; Shaw, George M.; Rayner, Julian C.; Peeters, Martine; Sharp, Paul M.; Bushman, Frederic D.; Hahn, Beatrice H.

2013-01-01

Wild-living chimpanzees and gorillas harbor a multitude of Plasmodium species, including six of the subgenus Laverania, one of which served as the progenitor of Plasmodium falciparum. Despite the magnitude of this reservoir, it is unknown whether apes represent a source of human infections. Here, we used Plasmodium species-specific PCR, single-genome amplification, and 454 sequencing to screen humans from remote areas of southern Cameroon for ape Laverania infections. Among 1,402 blood samples, we found 1,000 to be Plasmodium mitochondrial DNA (mtDNA) positive, all of which contained human parasites as determined by sequencing and/or restriction enzyme digestion. To exclude low-abundance infections, we subjected 514 of these samples to 454 sequencing, targeting a region of the mtDNA genome that distinguishes ape from human Laverania species. Using algorithms specifically developed to differentiate rare Plasmodium variants from 454-sequencing error, we identified single and mixed-species infections with P. falciparum, Plasmodium malariae, and/or Plasmodium ovale. However, none of the human samples contained ape Laverania parasites, including the gorilla precursor of P. falciparum. To characterize further the diversity of P. falciparum in Cameroon, we used single-genome amplification to amplify 3.4-kb mtDNA fragments from 229 infected humans. Phylogenetic analysis identified 62 new variants, all of which clustered with extant P. falciparum, providing further evidence that P. falciparum emerged following a single gorilla-to-human transmission. Thus, unlike Plasmodium knowlesi-infected macaques in southeast Asia, African apes harboring Laverania parasites do not seem to serve as a recurrent source of human malaria, a finding of import to ongoing control and eradication measures. PMID:23569255

Response to various periods of mechanical stimuli in Physarum plasmodium

NASA Astrophysics Data System (ADS)

Umedachi, Takuya; Ito, Kentaro; Kobayashi, Ryo; Ishiguro, Akio; Nakagaki, Toshiyuki

2017-06-01

Response to mechanical stimuli is a fundamental and critical ability for living cells to survive in hazardous conditions or to form adaptive and functional structures against force(s) from the environment. Although this ability has been extensively studied by molecular biology strategies, it is also important to investigate the ability from the viewpoint of biological rhythm phenomena so as to reveal the mechanisms that underlie these phenomena. Here, we use the plasmodium of the true slime mold Physarum polycephalum as the experimental system for investigating this ability. The plasmodium was repetitively stretched for various periods during which its locomotion speed was observed. Since the plasmodium has inherent oscillation cycles of protoplasmic streaming and thickness variation, how the plasmodium responds to various periods of external stretching stimuli can shed light on the other biological rhythm phenomena. The experimental results show that the plasmodium exhibits response to periodic mechanical stimulation and changes its locomotion speed depending on the period of the stretching stimuli.

Susceptibility of human Plasmodium knowlesi infections to anti-malarials

PubMed Central

2013-01-01

Background Evidence suggests that Plasmodium knowlesi malaria in Sarawak, Malaysian Borneo remains zoonotic, meaning anti-malarial drug resistance is unlikely to have developed in the absence of drug selection pressure. Therefore, adequate response to available anti-malarial treatments is assumed. Methods Here the ex vivo sensitivity of human P. knowlesi isolates in Malaysian Borneo were studied, using a WHO schizont maturation assay modified to accommodate the quotidian life cycle of this parasite. The in vitro sensitivities of P. knowlesi H strain adapted from a primate infection to in vitro culture (by measuring the production of Plasmodium lactate dehydrogenase) were also examined together with some assays using Plasmodium falciparum and Plasmodium vivax. Results Plasmodium knowlesi is uniformly highly sensitive to artemisinins, variably and moderately sensitive to chloroquine, and less sensitive to mefloquine. Conclusions Taken together with reports of clinical failures when P. knowlesi is treated with mefloquine, the data suggest that caution is required if using mefloquine in prevention or treatment of P. knowlesi infections, until further studies are undertaken. PMID:24245918

The Plasmodium selenoproteome

PubMed Central

Lobanov, Alexey V.; Delgado, Cesar; Rahlfs, Stefan; Novoselov, Sergey V.; Kryukov, Gregory V.; Gromer, Stephan; Hatfield, Dolph L.; Becker, Katja; Gladyshev, Vadim N.

2006-01-01

The use of selenocysteine (Sec) as the 21st amino acid in the genetic code has been described in all three major domains of life. However, within eukaryotes, selenoproteins are only known in animals and algae. In this study, we characterized selenoproteomes and Sec insertion systems in protozoan Apicomplexa parasites. We found that among these organisms, Plasmodium and Toxoplasma utilized Sec, whereas Cryptosporidium did not. However, Plasmodium had no homologs of known selenoproteins. By searching computationally for evolutionarily conserved selenocysteine insertion sequence (SECIS) elements, which are RNA structures involved in Sec insertion, we identified four unique Plasmodium falciparum selenoprotein genes. These selenoproteins were incorrectly annotated in PlasmoDB, were conserved in other Plasmodia and had no detectable homologs in other species. We provide evidence that two Plasmodium SECIS elements supported Sec insertion into parasite and endogenous selenoproteins when they were expressed in mammalian cells, demonstrating that the Plasmodium SECIS elements are functional and indicating conservation of Sec insertion between Apicomplexa and animals. Dependence of the plasmodial parasites on selenium suggests possible strategies for antimalarial drug development. PMID:16428245

African great apes are natural hosts of multiple related malaria species, including Plasmodium falciparum

PubMed Central

Prugnolle, Franck; Durand, Patrick; Neel, Cécile; Ollomo, Benjamin; Ayala, Francisco J.; Arnathau, Céline; Etienne, Lucie; Mpoudi-Ngole, Eitel; Nkoghe, Dieudonné; Leroy, Eric; Delaporte, Eric; Peeters, Martine; Renaud, François

2010-01-01

Plasmodium reichenowi, a chimpanzee parasite, was until very recently the only known close relative of Plasmodium falciparum, the most virulent agent of human malaria. Recently, Plasmodium gaboni, another closely related chimpanzee parasite, was discovered, suggesting that the diversity of Plasmodium circulating in great apes in Africa might have been underestimated. It was also recently shown that P. reichenowi is a geographically widespread and genetically diverse chimpanzee parasite and that the world diversity of P. falciparum is fully included within the much broader genetic diversity of P. reichenowi. The evidence indicates that all extant populations of P. falciparum originated from P. reichenowi, likely by a single transfer from chimpanzees. In this work, we have studied the diversity of Plasmodium species infecting chimpanzees and gorillas in Central Africa (Cameroon and Gabon) from both wild-living and captive animals. The studies in wild apes used noninvasive sampling methods. We confirm the presence of P. reichenowi and P. gaboni in wild chimpanzees. Moreover, our results reveal the existence of an unexpected genetic diversity of Plasmodium lineages circulating in gorillas. We show that gorillas are naturally infected by two related lineages of parasites that have not been described previously, herein referred to as Plasmodium GorA and P. GorB, but also by P. falciparum, a species previously considered as strictly human specific. The continuously increasing contacts between humans and primate populations raise concerns about further reciprocal host transfers of these pathogens. PMID:20133889

Test and Evaluation of Field-Deployable Infectious Disease Diagnostic Assays in Support of the Joint Biological Agent Identification and Diagnosis System (JBAIDS): Malaria (Plasmodium/JBAIDS)

DTIC Science & Technology

2012-05-31

plasmid and P . falciparum plasmid. The assay was 100% (17/17) concordant in testing using a diverse panel ofPiasmodium species and strains prepared...AFMSA O&M FY10 ‘Plasmodium Project’, existing Plasmodium genus, P . falciparum , and P . vivax TaqMan assays were proposed for transfer to the RAPID...using P . vivax plasmid and P . falciparum plasmid. The assay was 100% (17/17) concordant in testing using a diverse panel of Plasmodium species and

The use of Aotus Trivirgatus and Macaca Mulatta as Tools for Studies on Prevention and Therapy of Infections with Plasmodium Falciparum and Plasmodium Vivax

DTIC Science & Technology

1976-08-13

INFECTIONS WITH PLASMODIUM FALCIPARUM AND PLASMODIUM VIVAX (U) FINAL PROGRESS REPORT ( PROJECT 2284-XXIX) For the Period I May 1975 to 30 April...IT» IOC mit settiM I’jtf Section ^ I» ’■■■■• BisTtmunM/MWUiiun cooa DiJÜ iWBU. UK/» FINAL PROGRESS REPORT ( PROJECT 2284-XXIX) S...quinolinemethanols pyridinemethanols I ’As in previous years, the activities of this Project were focused on development of: (a) agents fully effective

Extremely low Plasmodium prevalence in wild plovers and coursers from Cape Verde and Madagascar.

PubMed

Martínez-de la Puente, Josué; Eberhart-Phillips, Luke J; Cristina Carmona-Isunza, M; Zefania, Sama; Navarro, María José; Kruger, Oliver; Hoffman, Joseph Ivan; Székely, Tamás; Figuerola, Jordi

2017-06-08

Relatively little is known about the prevalence of blood parasites in shorebirds, especially those breeding in the tropics. The prevalence of blood parasites of the genera Plasmodium, Haemoproteus and Leucocytozoon was assessed in blood samples from Kentish plovers and cream-coloured coursers in Cape Verde, and samples of Kittlitz's plovers, Madagascar plovers and white-fronted plovers in Madagascar. Only two of these samples were positive for Plasmodium: a Kittlitz's plover was infected by a generalist lineage of Plasmodium that has already been reported in Europe and Africa, while in a white-fronted plover direct sequencing revealed a previously un-described Plasmodium lineage. Potential explanations for the low prevalence of blood parasites include the scarcity of vectors in habitats used by these bird species and their resistance to parasitic infections.

Transmission of human and macaque Plasmodium spp. to ex-captive orangutans in Kalimantan, Indonesia.

PubMed

Reid, Michael J C; Ursic, Raul; Cooper, Dawn; Nazzari, Hamed; Griffiths, Melinda; Galdikas, Birute M; Garriga, Rosa M; Skinner, Mark; Lowenberger, Carl

2006-12-01

Data are lacking on the specific diseases to which great apes are susceptible and the transmission dynamics and overall impact of these diseases. We examined the prevalence of Plasmodium spp. infections in semicaptive orangutans housed at the Orangutan Care Center and Quarantine, Central Kalimantan, Indonesia, by using a combination of microscopic and DNA molecular techniques to identify the Plasmodium spp. in each animal. Previous studies indicated 2 orangutan-specific Plasmodium spp., but our data show 4 Plasmodium spp. These findings provide evidence for P. vivax transmission between humans and orangutans and for P. cynomolgi transmission between macaques and orangutans. These data have potential implications for the conservation of orangutans and also for the bidirectional transmission of parasites between orangutans and humans visiting or living in the region.

Transmission of Human and Macaque Plasmodium spp. to Ex-Captive Orangutans in Kalimantan, Indonesia

PubMed Central

Reid, Michael J.C.; Ursic, Raul; Cooper, Dawn; Nazzari, Hamed; Griffiths, Melinda; Galdikas, Birute M.; Garriga, Rosa M.; Skinner, Mark; Lowenberger, Carl

2006-01-01

Data are lacking on the specific diseases to which great apes are susceptible and the transmission dynamics and overall impact of these diseases. We examined the prevalence of Plasmodium spp. infections in semicaptive orangutans housed at the Orangutan Care Center and Quarantine, Central Kalimantan, Indonesia, by using a combination of microscopic and DNA molecular techniques to identify the Plasmodium spp. in each animal. Previous studies indicated 2 orangutan-specific Plasmodium spp., but our data show 4 Plasmodium spp. These findings provide evidence for P. vivax transmission between humans and orangutans and for P. cynomolgi transmission between macaques and orangutans. These data have potential implications for the conservation of orangutans and also for the bidirectional transmission of parasites between orangutans and humans visiting or living in the region. PMID:17326942

Systems Biology-Based Investigation of Host-Plasmodium Interactions.

PubMed

Smith, Maren L; Styczynski, Mark P

2018-05-18

Malaria is a serious, complex disease caused by parasites of the genus Plasmodium. Plasmodium parasites affect multiple tissues as they evade immune responses, replicate, sexually reproduce, and transmit between vertebrate and invertebrate hosts. The explosion of omics technologies has enabled large-scale collection of Plasmodium infection data, revealing systems-scale patterns, mechanisms of pathogenesis, and the ways that host and pathogen affect each other. Here, we provide an overview of recent efforts using systems biology approaches to study host-Plasmodium interactions and the biological themes that have emerged from these efforts. We discuss some of the challenges in using systems biology for this goal, key research efforts needed to address those issues, and promising future malaria applications of systems biology. Copyright © 2018 Elsevier Ltd. All rights reserved.

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

PubMed Central

Medeiros, Matthew C. I.; Hamer, Gabriel L.; Ricklefs, Robert E.

2013-01-01

Blood-feeding arthropod vectors are responsible for transmitting many parasites between vertebrate hosts. While arthropod vectors often feed on limited subsets of potential host species, little is known about the extent to which this influences the distribution of vector-borne parasites in some systems. Here, we test the hypothesis that different vector species structure parasite–host relationships by restricting access of certain parasites to a subset of available hosts. Specifically, we investigate how the feeding patterns of Culex mosquito vectors relate to distributions of avian malaria parasites among hosts in suburban Chicago, IL, USA. We show that Plasmodium lineages, defined by cytochrome b haplotypes, are heterogeneously distributed across avian hosts. However, the feeding patterns of the dominant vectors (Culex restuans and Culex pipiens) are similar across these hosts, and do not explain the distributions of Plasmodium parasites. Phylogenetic similarity of avian hosts predicts similarity in their Plasmodium parasites. This effect was driven primarily by the general association of Plasmodium parasites with particular host superfamilies. Our results suggest that a mosquito-imposed encounter rate does not limit the distribution of avian Plasmodium parasites across hosts. This implies that compatibility between parasites and their avian hosts structure Plasmodium host range. PMID:23595266

Coupled Oscillators System in the True Slime Mold

NASA Astrophysics Data System (ADS)

Takamatsu, A.; Fujii, T.; Endo, I.

The Plasmodium of true slime mold, Physarum polycephalum, which shows various oscillatory phenomena, can be regarded as a coupled nonlinear oscillators system. The partial bodies of the Plasmodium are interconnected by microscale tubes, whose dimension can be related to the coupling strength between the plasmodial oscillators. Investigation on the collective behavior of the oscillators under the condition that the configuration of the tube structure can be manipulated gives significant information on the characteristics of the Plasmodium from the viewpoint of nonlinear dynamics. In this study, we propose a living coupled oscillators system. Using a microfabricated structure, we patterned the geometry and the dimensions of the microscale tube structure of the Plasmodium. As the first step, the Plasmodium was grown in the microstructure for coupled two oscillators system that has two wells (oscillator part) and a microchannel (coupling part). We investigated the oscillation bahavior by monitoring the thickness oscillation of Plasmodium in the strucutre with various width (W) and length (L) of microchannel. We found that there are various types of oscillation bahavior, such as anti-phase and in-phase oscillations depending on the channel dimension W and L. The present method is suitable for further studies of the network of the Plasmodium as a collective nonlinear oscillators system.

Proposal for a new therapy for drug-resistant malaria using Plasmodium synthetic lethality inference.

PubMed

Lee, Sang Joon; Seo, Eunseok; Cho, Yonghyun

2013-12-01

Many antimalarial drugs kill malaria parasites, but antimalarial drug resistance (ADR) and toxicity to normal cells limit their usefulness. To solve this problem, we suggest a new therapy for drug-resistant malaria. The approach consists of data integration and inference through homology analysis of yeast-human-Plasmodium. If one gene of a Plasmodium synthetic lethal (SL) gene pair has a mutation that causes ADR, a drug targeting the other gene of the SL pair might be used as an effective treatment for drug-resistant strains of malaria. A simple computational tool to analyze the inferred SL genes of Plasmodium species (malaria parasites Plasmodium falciparum and Plasmodium vivax for human malarial therapy, and rodent parasite Plasmodium berghei for in vivo studies of human malarias) was established to identify SL genes that can be used as drug targets. Information on SL gene pairs with ADR genes and their first neighbors was inferred from yeast SL genes to search for pertinent antimalarial drug targets. We not only suggest drug target gene candidates for further experimental validation, but also provide information on new usage for already-described drugs. The proposed specific antimalarial drug candidates can be inferred by searching drugs that cause a fitness defect in yeast SL genes.

Slow and fast dynamics model of a Malaria with Sickle-Cell genetic disease with multi-stage infections of the mosquitoes population

NASA Astrophysics Data System (ADS)

Dewi Siawanta, Shanti; Adi-Kusumo, Fajar; Irwan Endrayanto, Aluicius

2018-03-01

Malaria, which is caused by Plasmodium, is a common disease in tropical areas. There are three types of Plasmodium i.e. Plasmodium Vivax, Plasmodium Malariae, and Plasmodium Falciparum. The most dangerous cases of the Malaria are mainly caused by the Plasmodium Falciparum. One of the important characteristics for the Plasmodium infection is due to the immunity of erythrocyte that contains HbS (Haemoglobin Sickle-cell) genes. The individuals who has the HbS gene has better immunity against the disease. In this paper, we consider a model that shows the spread of malaria involving the interaction between the mosquitos population, the human who has HbS genes population and the human with normal gene population. We do some analytical and numerical simulation to study the basic reproduction ratio and the slow-fast dynamics of the phase-portrait. The slow dynamics in our model represents the response of the human population with HbS gene to the Malaria disease while the fast dynamics show the response of the human population with the normal gene to the disease. The slow and fast dynamics phenomena are due to the fact that the population of the individuals who have HbS gene is much smaller than the individuals who has normal genes.

Limitations of microscopy to differentiate Plasmodium species in a region co-endemic for Plasmodium falciparum, Plasmodium vivax and Plasmodium knowlesi

PubMed Central

2013-01-01

Background In areas co-endemic for multiple Plasmodium species, correct diagnosis is crucial for appropriate treatment and surveillance. Species misidentification by microscopy has been reported in areas co-endemic for vivax and falciparum malaria, and may be more frequent in regions where Plasmodium knowlesi also commonly occurs. Methods This prospective study in Sabah, Malaysia, evaluated the accuracy of routine district and referral hospital-based microscopy, and microscopy performed by an experienced research microscopist, for the diagnosis of PCR-confirmed Plasmodium falciparum, P. knowlesi, and Plasmodium vivax malaria. Results A total of 304 patients with PCR-confirmed Plasmodium infection were enrolled, including 130 with P. knowlesi, 122 with P. falciparum, 43 with P. vivax, one with Plasmodium malariae and eight with mixed species infections. Among patients with P. knowlesi mono-infection, routine and cross-check microscopy both identified 94 (72%) patients as “P. malariae/P. knowlesi”; 17 (13%) and 28 (22%) respectively were identified as P. falciparum, and 13 (10%) and two (1.5%) as P. vivax. Among patients with PCR-confirmed P. falciparum, routine and cross-check microscopy identified 110/122 (90%) and 112/118 (95%) patients respectively as P. falciparum, and 8/122 (6.6%) and 5/118 (4.2%) as “P. malariae/P. knowlesi”. Among those with P. vivax, 23/43 (53%) and 34/40 (85%) were correctly diagnosed by routine and cross-check microscopy respectively, while 13/43 (30%) and 3/40 (7.5%) patients were diagnosed as “P. malariae/P. knowlesi”. Four of 13 patients with PCR-confirmed P. vivax and misdiagnosed by routine microscopy as “P. malariae/P. knowlesi” were subsequently re-admitted with P. vivax malaria. Conclusions Microscopy does not reliably distinguish between P. falciparum, P. vivax and P. knowlesi in a region where all three species frequently occur. Misdiagnosis of P. knowlesi as both P. vivax and P. falciparum, and vice versa, is common, potentially leading to inappropriate treatment, including chloroquine therapy for P. falciparum and a lack of anti-relapse therapy for P. vivax. The limitations of microscopy in P. knowlesi-endemic areas supports the use of unified blood-stage treatment strategies for all Plasmodium species, the development of accurate rapid diagnostic tests suitable for all species, and the use of PCR-confirmation for accurate surveillance. PMID:23294844

The detection of cryptic Plasmodium infection among villagers in Attapeu province, Lao PDR.

PubMed

Iwagami, Moritoshi; Keomalaphet, Sengdeuane; Khattignavong, Phonepadith; Soundala, Pheovaly; Lorphachan, Lavy; Matsumoto-Takahashi, Emilie; Strobel, Michel; Reinharz, Daniel; Phommasansack, Manisack; Hongvanthong, Bouasy; Brey, Paul T; Kano, Shigeyuki

2017-12-01

Although the malaria burden in the Lao PDR has gradually decreased, the elimination of malaria by 2030 presents many challenges. Microscopy and malaria rapid diagnostic tests (RDTs) are used to diagnose malaria in the Lao PDR; however, some studies have reported the prevalence of sub-microscopic Plasmodium infections or asymptomatic Plasmodium carriers in endemic areas. Thus, highly sensitive detection methods are needed to understand the precise malaria situation in these areas. A cross-sectional malaria field survey was conducted in 3 highly endemic malaria districts (Xaysetha, Sanamxay, Phouvong) in Attapeu province, Lao PDR in 2015, to investigate the precise malaria endemicity in the area; 719 volunteers from these villages participated in the survey. Microscopy, RDTs and a real-time nested PCR were used to detect Plasmodium infections and their results were compared. A questionnaire survey of all participants was also conducted to estimate risk factors of Plasmodium infection. Numbers of infections detected by the three methods were microscopy: P. falciparum (n = 1), P. vivax (n = 2); RDTs: P. falciparum (n = 2), P. vivax (n = 3); PCR: Plasmodium (n = 47; P. falciparum [n = 4], P. vivax [n = 41], mixed infection [n = 2]; 6.5%, 47/719). Using PCR as a reference, the sensitivity and specificity of microscopy were 33.3% and 100.0%, respectively, for detecting P. falciparum infection, and 7.0% and 100.0%, for detecting P. vivax infection. Among the 47 participants with parasitemia, only one had a fever (≥37.5°C) and 31 (66.0%) were adult males. Risk factors of Plasmodium infection were males and soldiers, whereas a risk factor of asymptomatic Plasmodium infection was a history of ≥3 malaria episodes. There were many asymptomatic Plasmodium carriers in the study areas of Attapeu province in 2015. Adult males, probably soldiers, were at high risk for malaria infection. P. vivax, the dominant species, accounted for 87.2% of the Plasmodium infections among the participants. To achieve malaria elimination in the Lao PDR, highly sensitive diagnostic tests, including PCR-based diagnostic methods should be used, and plans targeting high-risk populations and elimination of P. vivax should be designed and implemented.

Multiple lineages of Avian malaria parasites (Plasmodium) in the Galapagos Islands and evidence for arrival via migratory birds.

PubMed

Levin, I I; Zwiers, P; Deem, S L; Geest, E A; Higashiguchi, J M; Iezhova, T A; Jiménez-Uzcátegui, G; Kim, D H; Morton, J P; Perlut, N G; Renfrew, R B; Sari, E H R; Valkiunas, G; Parker, P G

2013-12-01

Haemosporidian parasites in the genus Plasmodium were recently detected through molecular screening in the Galapagos Penguin (Spheniscus mendiculus). We summarized results of an archipelago-wide screen of 3726 endemic birds representing 22 species for Plasmodium spp. through a combination of molecular and microscopy techniques. Three additional Plasmodium lineages were present in Galapagos. Lineage A-infected penguins, Yellow Warblers (Setophaga petechia aureola), and one Medium Ground Finch (Geospiza fortis) and was detected at multiple sites in multiple years [corrected]. The other 3 lineages were each detected at one site and at one time; apparently, they were transient infections of parasites not established on the archipelago. No gametocytes were found in blood smears of infected individuals; thus, endemic Galapagos birds may be dead-end hosts for these Plasmodium lineages. Determining when and how parasites and pathogens arrive in Galapagos is key to developing conservation strategies to prevent and mitigate the effects of introduced diseases. To assess the potential for Plasmodium parasites to arrive via migratory birds, we analyzed blood samples from 438 North American breeding Bobolinks (Dolichonyx oryzivorus), the only songbird that regularly migrates through Galapagos. Two of the ephemeral Plasmodium lineages (B and C) found in Galapagos birds matched parasite sequences from Bobolinks. Although this is not confirmation that Bobolinks are responsible for introducing these lineages, evidence points to higher potential arrival rates of avian pathogens than previously thought. Linajes Múltiples de Parásitos de Malaria Aviar (Plasmodium) en las Islas Galápagos y Evidencia de su Arribo por Medio de Aves Migratorias. © 2013 Society for Conservation Biology.

Drug Evaluation in the Plasmodium falciparum - Aotus Model

DTIC Science & Technology

1984-09-01

consecutive days to Colombian Aotus. Six amodiaquin analogues were evaluated for their capacity to cure in- fections of chloroquine -sensitive and...AMODIAQUIN ANALOGUES AND AMODIAQUIN AGAINST INFECTIONS OF CHLOROQUINE -SENSITIVE AND CHLOROQUINE -RESISTANT STRAINS OF PLASMODIUM FALCIPARUM 14...AMODIAQUIN ANALOGUES AND AMOOIAQUIN AGAINST INFECTIONS OF CHLOROQUINE -SENSITIVE AND CHLOROQUINE - RESISTANT STRAINS OF PLASMODIUM FALCIPARUM Following

Helminth parasites alter protection against Plasmodium infection.

PubMed

Salazar-Castañon, Víctor H; Legorreta-Herrera, Martha; Rodriguez-Sosa, Miriam

2014-01-01

More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.

Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

PubMed Central

Rosero, Doris A.; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V.; Luckhart, Shirley

2013-01-01

The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia. PMID:27335865

Colombian Anopheles triannulatus (Diptera: Culicidae) Naturally Infected with Plasmodium spp.

PubMed

Rosero, Doris A; Naranjo-Diaz, Nelson; Alvarez, Natalí; Cienfuegos, Astrid V; Torres, Carolina; Luckhart, Shirley; Correa, Margarita M

2013-01-01

The role of Anopheles triannulatus as a local vector has not yet been defined for malaria-endemic regions of Colombia. Therefore, the aim of this work was to detect An. triannulatus naturally infected with Plasmodium spp., as an approximation to determining its importance as malaria vector in the country. A total of 510 An. triannulatus were collected in six malaria-endemic localities of NW and SE Colombia from January 2009 to March 2011. In the NW, two specimens were naturally infected; one with Plasmodium vivax VK247, collected biting on humans and the other with Plasmodium falciparum, collected resting on cattle. In the SE, two specimens were positive for P. falciparum. Although these results show An. triannulatus naturally infected with Plasmodium, further studies are recommended to demonstrate the epidemiological importance of this species in malaria-endemic regions of Colombia.

Blood schizontocidal activity of WR 238605 (Tafenoquine) against Plasmodium cynomolgi and Plasmodium fragile infections in rhesus monkeys.

PubMed

Puri, S K; Dutta, G P

2003-04-01

A new 8-aminoquinoline antimalarial WR 238605 (Tafenoquine), developed initially as a primaquine alternative for prevention of Plasmodium vivax relapses was evaluated for blood schizontocidal activity against two simian malaria infections namely Plasmodium cynomolgi B and Plasmodium fragile in rhesus monkeys. Treatment with WR 238605 at a dose of 3.16 mg(base)/kg/day x 7 days cured established trophozoite induced infections in monkeys with both these parasites. The lower dose of 1.00 mg/kg/day cured 9 out of 12 monkeys infected with P. cynomolgi B and 10 out of 11 monkeys infected with P. fragile. Primaquine was only partially curative at 10.0 mg(base)/kg/day x 7 dose regimen against both these infections. The potent blood schizontocidal activity of tafenoquine adds to the armoury of antimalarial drugs.

Cytokine profiles among patients co-infected with Plasmodium falciparum malaria and soil borne helminths attending Kampala International University Teaching Hospital, in Uganda.

PubMed

Bwanika, Richard; Kato, Charles D; Welishe, Johnson; Mwandah, Daniel C

2018-01-01

Malaria and helminths share the same geographical distribution in tropical Africa. Studies of the interaction of helminth and malaria co-infection in humans have been few and are mainly epidemiological, with little information on cellular immune responses. This study aimed to determine Cytokine profiles among patients co-infected with Plasmodium falciparum malaria and soil borne helminth attending Kampala International University Teaching Hospital (KIU). A case control study of 240 patients were recruited at KIU teaching hospital. Patients with Plasmodium falciparum malaria were 55 (22.9%) and those with soil-borne helminths were 63 (26.3%). The controls were 89 (37.1%), while those co-infected with Plasmodium falciparum malaria and soil-borne helminths were 33 (13.8%). Cases were defined as having a positive blood smear for P. falciparum malaria, those with helminths or co-infections of the two. Negative controls were those with a negative blood smear for P. falciparum malaria and those with no stool parasitic infections. Patients presenting with signs and symptoms of malaria or those suspected of having helminths were recruited for the study. A panel of five cytokines (IFN-γ, TNF-α, IL-6, TGF-β and IL-10) were assayed from plasma samples in patients with and without Plasmodium falciparum malaria, patients with and without helminth, and then those co-infected with the two diseases diagnosis was done using thick blood smears stained with 10% Giemsa and stool examination was done following the Kato Katz technique following standard procedures. The prevalence of Plasmodium falciparum malaria by sex was 28 (11.7%) and 27 (11.3%) in male and female respectively. The overall prevalence of soil borne helminth was 26.3%, and among those harbouring helminths, 13.8% were co-infected with Plasmodium falciparum. Cytokine levels significantly differed across Plasmodium falciparum malaria, soil borne helminth infected patients and health controls for IFN-γ (P = 0.023), IL-10 (P = 0.008) and TGF-β (P = 0.0001). Cytokine levels significantly differed across Plasmodium falciparum malaria, soil borne helminth infected patients and patients co-infected with Plasmodium falciparum malaria and soil borne helminth for IL-10 (P = 0.004), IL-6 (P = 0.011) and TGF-β (P = 0.003). An up-regulation of IFN-γ during Plasmodium falciparum malaria and an up-regulation of IL-10 and TGF-β in soil borne helminth infections was demonstrated. We demonstrate that co-infections of Plasmodium falciparum and soil borne helminth lead to an up-regulation of IL-10 and IL-6 and a down-regulation of TGF-β. Trial registration No17/10-16.

Patterns of Plasmodium vivax and Plasmodium falciparum malaria underscore importance of data collection from private health care facilities in India.

PubMed

Gupta, Sangeeta; Gunter, James T; Novak, Robert J; Regens, James L

2009-10-12

This study describes patterns of falciparum and vivax malaria in a private comprehensive-care, multi-specialty hospital in New Delhi from July 2006 to July 2008. Malarial morbidity by Plasmodium species (Plasmodium falciparum, Plasmodium vivax, or Plasmodium sp.) was confirmed using microscopy and antigen tests. The influence of seasonal factors and selected patient demographics on morbidity was evaluated. The proportions of malaria cases caused by P. falciparum at the private facility were compared to data from India's National Vector Borne Disease Control Programme (NVBDCP) during the same period for the Delhi region. In New Delhi, P. faciparum was the dominant cause of cases requiring treatment in the private hospital during the period examined. The national data reported a smaller proportion of malaria cases caused by P. falciparum in the national capital region than was observed in a private facility within the region. Plasmodium vivax also caused a large proportion of the cases presenting clinically at the private hospital during the summer and monsoon seasons. The proportion of P. falciparum malaria cases tends to be greatest during the post-monsoon season while the proportion of P. vivax malaria cases tends to be greatest in the monsoon season. Private hospital data demonstrate an under-reporting of malaria case incidences in the data from India's national surveillance programme during the same period for the national capital region.

Blood parasites from California ducks and geese

USGS Publications Warehouse

Herman, C.M.

1951-01-01

Blood smears were procured from 1,011 geese and ducks of 19 species from various locations in California. Parasites were found in 28 individuals. The parasites observed included Haemoproteus hermani, Leucocytozoon simondi, microfilaria, Plasmodium relictum (=P. biziurae), and Plasmodium sp. with elongate gametocytes. This is the first report of a natural infection with a Plasmodium in North American wild ducks.

Effect of chloroquine on gene expression of Plasmodium yoelii nigeriensis during its sporogonic development in the mosquito vector

PubMed Central

Silveira, Henrique; Ramos, Susana; Abrantes, Patrícia; Lopes, Luís Filipe; do Rosario, Virgílio E; Abrahamsen, Mitchell S

2007-01-01

Background The anti-malarial chloroquine can modulate the outcome of infection during the Plasmodium sporogonic development, interfering with Plasmodium gene expression and subsequently, with transmission. The present study sets to identify Plasmodium genes that might be regulated by chloroquine in the mosquito vector. Methods Differential display RT-PCR (DDRT-PCR) was used to identify genes expressed during the sporogonic cycle that are regulated by exposure to chloroquine. Anopheles stephensi mosquitoes were fed on Plasmodium yoelii nigeriensis-infected mice. Three days post-infection, mosquitoes were fed a non-infectious blood meal from mice treated orally with 50 mg/kg chloroquine. Two differentially expressed Plasmodium transcripts (Pyn_chl091 and Pyn_chl055) were further characterized by DNA sequencing and real-time PCR analysis. Results Both transcripts were represented in Plasmodium EST databases, but displayed no homology with any known genes. Pyn_chl091 was upregulated by day 18 post infection when the mosquito had a second blood meal. However, when the effect of chloroquine on that transcript was investigated during the erythrocytic cycle, no significant differences were observed. Although slightly upregulated by chloroquine exposure the expression of Pyn_chl055 was more affected by development, increasing towards the end of the sporogonic cycle. Transcript abundance of Pyn_chl055 was reduced when erythrocytic stages were treated with chloroquine. Conclusion Chloroquine increased parasite load in mosquito salivary glands and interferes with the expression of at least two Plasmodium genes. The transcripts identified contain putative signal peptides and transmembrane domains suggesting that these proteins, due to their location, are targets of chloroquine (not as an antimalarial) probably through cell trafficking and recycling. PMID:17605769

Avian Plasmodium in Culex and Ochlerotatus Mosquitoes from Southern Spain: Effects of Season and Host-Feeding Source on Parasite Dynamics

PubMed Central

Ferraguti, Martina; Martínez-de la Puente, Josué; Muñoz, Joaquín; Roiz, David; Ruiz, Santiago; Soriguer, Ramón; Figuerola, Jordi

2013-01-01

Haemosporidians, a group of vector-borne parasites that include Plasmodium, infect vertebrates including birds. Although mosquitoes are crucial elements in the transmission of avian malaria parasites, little is known of their ecology as vectors. We examined the presence of Plasmodium and Haemoproteus lineages in five mosquito species belonging to the genera Culex and Ochlerotatus to test for the effect of vector species, season and host-feeding source on the transmission dynamics of these pathogens. We analyzed 166 blood-fed individually and 5,579 unfed mosquitoes (grouped in 197 pools) from a locality in southern Spain. In all, 15 Plasmodium and two Haemoproteus lineages were identified on the basis of a fragment of 478 bp of the mitochondrial cytochrome b gene. Infection prevalence of blood parasites in unfed mosquitoes varied between species (range: 0–3.2%) and seasons. The feeding source was identified in 91 mosquitoes where 78% were identified as bird. We found that i) several Plasmodium lineages are shared among different Culex species and one Plasmodium lineage is shared between Culex and Ochlerotatus genera; ii) mosquitoes harboured Haemoproteus parasites; iii) pools of unfed females of mostly ornithophilic Culex species had a higher Plasmodium prevalence than the only mammophylic Culex species studied. However, the mammophylic Ochlerotatus caspius had in pool samples the greatest Plasmodium prevalence. This relative high prevalence may be determined by inter-specific differences in vector survival, susceptibility to infection but also the possibility that this species feeds on birds more frequently than previously thought. Finally, iv) infection rate of mosquitoes varies between seasons and reaches its maximum prevalence during autumn and minimum prevalence in spring. PMID:23823127

Hemoparasites in a wild primate: Infection patterns suggest interaction of Plasmodium and Babesia in a lemur species☆

PubMed Central

Springer, Andrea; Fichtel, Claudia; Calvignac-Spencer, Sébastien; Leendertz, Fabian H.; Kappeler, Peter M.

2015-01-01

Hemoparasites can cause serious morbidity in humans and animals and often involve wildlife reservoirs. Understanding patterns of hemoparasite infections in natural populations can therefore inform about emerging disease risks, especially in the light of climate change and human disruption of natural ecosystems. We investigated the effects of host age, sex, host group size and season on infection patterns of Plasmodium sp., Babesia sp. and filarial nematodes in a population of wild Malagasy primates, Verreaux's sifakas (Propithecus verreauxi), as well as the effects of these infections on hematological variables. We tested 45 blood samples from 36 individuals and identified two species of Plasmodium, one species of Babesia and two species of filarial nematodes. Plasmodium spp. and Babesia sp. infections showed opposite patterns of age-dependency, with babesiosis being prevalent among young animals, while older animals were infected with Plasmodium sp. In addition, Babesia sp. infection was a statistically significant negative predictor of Plasmodium sp. infection. These results suggest that Plasmodium and Babesia parasites may interact within the host, either through cross-immunity or via resource competition, so that Plasmodium infections can only establish after babesiosis has resolved. We found no effects of host sex, host group size and season on hemoparasite infections. Infections showed high prevalences and did not influence hematological variables. This preliminary evidence supports the impression that the hosts and parasites considered in this study appear to be well-adapted to each other, resulting in persistent infections with low pathogenic and probably low zoonotic potential. Our results illustrate the crucial role of biodiversity in host-parasite relationships, specifically how within-host pathogen diversity may regulate the abundance of parasites. PMID:26767166

Hemoparasites in a wild primate: Infection patterns suggest interaction of Plasmodium and Babesia in a lemur species.

PubMed

Springer, Andrea; Fichtel, Claudia; Calvignac-Spencer, Sébastien; Leendertz, Fabian H; Kappeler, Peter M

2015-12-01

Hemoparasites can cause serious morbidity in humans and animals and often involve wildlife reservoirs. Understanding patterns of hemoparasite infections in natural populations can therefore inform about emerging disease risks, especially in the light of climate change and human disruption of natural ecosystems. We investigated the effects of host age, sex, host group size and season on infection patterns of Plasmodium sp., Babesia sp. and filarial nematodes in a population of wild Malagasy primates, Verreaux's sifakas (Propithecus verreauxi), as well as the effects of these infections on hematological variables. We tested 45 blood samples from 36 individuals and identified two species of Plasmodium, one species of Babesia and two species of filarial nematodes. Plasmodium spp. and Babesia sp. infections showed opposite patterns of age-dependency, with babesiosis being prevalent among young animals, while older animals were infected with Plasmodium sp. In addition, Babesia sp. infection was a statistically significant negative predictor of Plasmodium sp. infection. These results suggest that Plasmodium and Babesia parasites may interact within the host, either through cross-immunity or via resource competition, so that Plasmodium infections can only establish after babesiosis has resolved. We found no effects of host sex, host group size and season on hemoparasite infections. Infections showed high prevalences and did not influence hematological variables. This preliminary evidence supports the impression that the hosts and parasites considered in this study appear to be well-adapted to each other, resulting in persistent infections with low pathogenic and probably low zoonotic potential. Our results illustrate the crucial role of biodiversity in host-parasite relationships, specifically how within-host pathogen diversity may regulate the abundance of parasites.

Development of a rapid HRM qPCR for the diagnosis of the four most prevalent Plasmodium lineages in New Zealand.

PubMed

Schoener, E R; Hunter, S; Howe, L

2017-07-01

Although wildlife rehabilitation and translocations are important tools in wildlife conservation in New Zealand, disease screening of birds has not been standardized. Additionally, the results of the screening programmes are often difficult to interpret due to missing disease data in resident or translocating avian populations. Molecular methods have become the most widespread method for diagnosing avian malaria (Plasmodium spp.) infections. However, these methods can be time-consuming, expensive and are less specific in diagnosing mixed infections. Thus, this study developed a new real-time PCR (qPCR) method that was able to detect and specifically identify infections of the three most common lineages of avian malaria in New Zealand (Plasmodium (Novyella) sp. SYAT05, Plasmodium elongatum GRW6 and Plasmodium spp. LINN1) as well as a less common, pathogenic Plasmodium relictum GRW4 lineage. The assay was also able to discern combinations of these parasites in the same sample and had a detection limit of five parasites per microlitre. Due to concerns relating to the presence of the potentially highly pathogenic P. relictum GRW4 lineage in avian populations, an additional confirmatory high resolution (HRM) qPCR was developed to distinguish between commonly identified P. elongatum GRW6 from P. relictum GRW4. The new qPCR assays were tested using tissue samples containing Plasmodium schizonts from three naturally infected dead birds resulting in the identified infection of P. elongatum GRW6. Thus, these rapid qPCR assays have shown to be cost-effective and rapid screening tools for the detection of Plasmodium infection in New Zealand native birds.

Test characteristics of the SD FK80 Plasmodium falciparum/Plasmodium vivax malaria rapid diagnostic test in a non-endemic setting

PubMed Central

2009-01-01

Background The SD FK80 P.f/P.v Malaria Antigen Rapid Test (Standard Diagnostics, Korea) (FK80) is a three-band malaria rapid diagnostic test detecting Plasmodium falciparum histidine-rich protein-2 (HRP-2) and Plasmodium vivax-specific lactate dehydrogenase (Pv-pLDH). The present study assessed its performance in a non-endemic setting. Methods Stored blood samples (n = 416) from international travellers suspected of malaria were used, with microscopy corrected by PCR as the reference method. Samples infected by Plasmodium falciparum (n = 178), Plasmodium vivax (n = 99), Plasmodium ovale (n = 75) and Plasmodium malariae (n = 24) were included, as well as 40 malaria negative samples. Results Overall sensitivities for the diagnosis of P. falciparum and P. vivax were 91.6% (95% confidence interval (CI): 86.2% - 95.0%) and 75.8% (65.9% - 83.6%). For P. falciparum, sensitivity at parasite densities ≥ 100/μl was 94.6% (88.8% - 97.6%); for P. vivax, sensitivity at parasite densities ≥ 500/μl was 86.8% (75.4% - 93.4%). Four P. falciparum samples showed a Pv-pLDH line, three of them had parasite densities exceeding 50.000/μl. Two P. vivax samples, one P. ovale and one P. malariae sample showed a HRP-2 line. For the HRP-2 and Pv-pLDH lines, respectively 81.4% (136/167) and 55.8% (43/77) of the true positive results were read as medium or strong line intensities. The FK80 showed good reproducibility and reliability for test results and line intensities (kappa values for both exceeding 0.80). Conclusion The FK80 test performed satisfactorily in diagnosing P. falciparum and P. vivax infections in a non-endemic setting. PMID:19930609

Primate malarias: Diversity, distribution and insights for zoonotic Plasmodium.

PubMed

Faust, Christina; Dobson, Andrew P

2015-12-01

Protozoans within the genus Plasmodium are well-known as the causative agents of malaria in humans. Numerous Plasmodium species parasites also infect a wide range of non-human primate hosts in tropical and sub-tropical regions worldwide. Studying this diversity can provide critical insight into our understanding of human malarias, as several human malaria species are a result of host switches from non-human primates. Current spillover of a monkey malaria, Plasmodium knowlesi , in Southeast Asia highlights the permeability of species barriers in Plasmodium . Also recently, surveys of apes in Africa uncovered a previously undescribed diversity of Plasmodium in chimpanzees and gorillas. Therefore, we carried out a meta-analysis to quantify the global distribution, host range, and diversity of known non-human primate malaria species. We used published records of Plasmodium parasites found in non-human primates to estimate the total diversity of non-human primate malarias globally. We estimate that at least three undescribed primate malaria species exist in sampled primates, and many more likely exist in unstudied species. The diversity of malaria parasites is especially uncertain in regions of low sampling such as Madagascar, and taxonomic groups such as African Old World Monkeys and gibbons. Presence-absence data of malaria across primates enables us to highlight the close association of forested regions and non-human primate malarias. This distribution potentially reflects a long coevolution of primates, forest-adapted mosquitoes, and malaria parasites. The diversity and distribution of primate malaria are an essential prerequisite to understanding the mechanisms and circumstances that allow Plasmodium to jump species barriers, both in the evolution of malaria parasites and current cases of spillover into humans.

[Application of Nested PCR in the Diagnosis of Imported Plasmodium Ovale Infection].

PubMed

Huang, Bing-cheng; Xu, Chao; Li, Jin; Xiao, Ting; Yin, Kun; Liu, Gong-zhen; Wang, Wei-yan; Zhao, Gui-hua; Wei, Yan-bin; Wang, Yong-bin; Zhao, Chang-lei; Wei, Qing-kuan

2015-02-01

To identity Plasmodium ovale infection by 18S rRNA gene nested PCR. Whole blood and filter paper blood samples of malaria patients in Shandong Province were collected during 2012-2013. The parasites were observed under a microscope with Giemsa staining. The genome DNA of blood samples were extracted as PCR templates. Genus- and species-specific primers were designed according to the Plasmodium 18S rRNA gene sequences. Plasmodium ovale-positive specimens were identified by nested PCR as well as verified by sequencing. There were 7 imported cases of P. ovale infection in the province during 2012-2013. Nested PCR results showed that the P. ovale specific band (800 bp) was amplified in all the 7 specimens. Blast results indicated that the PCR products were consistent with the Plasmodium ovale reference sequence in GenBank. Seven imported cases of ovale malaria in Shandong Province in 2012-2013 are confirmed by nested PCR.

Molecular detection of Plasmodium in free-ranging birds and captive flamingos (Phoenicopterus chilensis) in Chicago.

PubMed

Thurber, Mary Irene; Gamble, Kathryn C; Krebs, Bethany; Goldberg, Tony L

2014-12-01

Frozen blood samples from 13 species of free-ranging birds (n = 65) and captive Chilean flamingos (Phoenicopterus chilensis) (n = 46) housed outdoors in the Chicago area were screened for Plasmodium. With the use of a modified polymerase chain reaction, 20/65 (30.8%) of free-ranging birds and 26/46 (56.5%) of flamingos were classified as positive for this parasite genus. DNA sequencing of the parasite cytochrome b gene in positive samples demonstrated that eight species of free-ranging birds were infected with five different Plasmodium spp. cytochrome b lineages, and all positive Chilean flamingos were infected with Plasmodium spp. cytochrome b lineages most closely related to organisms in the Novyella subgenus. These results show that Chilean flamingos may harbor subclinical malaria infections more frequently than previously estimated, and that they may have increased susceptibility to some Plasmodium species.

Drug Evaluation in the Plasmodium Falciparum-Aotus Model.

DTIC Science & Technology

1986-09-30

strains of Plasmodium falciparum, Uganda Palo Alto ( chloroquine sensi- tive) or Vietnam Smith (chioroquine resistant), in Aotus trivirgatus, were used...Plasmodium falciparum in the Panamanian owl monkey Aotus Two strains of falciparum malaria, Uganda Palo Alto (sensitive to chloroquine anfd quinine...resistant to pyrimetha- mine) and Vietnam Smith (resistant to chloroquine , quinine and pyrimethamine) were used. Previous evaluation of two stereoisomers of

Case report: spontaneous rupture of spleen in patient with Plasmodium ovale malaria.

PubMed

Lemmerer, Raphael; Unger, Manuel; Voßen, Matthias; Forstner, Christina; Jalili, Ahmad; Starzengruber, Peter; Werzowa, Johannes; Ramharter, Michael; Winkler, Stefan; Thalhammer, Florian

2016-01-01

Malaria may lead to spontaneous splenic rupture as a rare but potentially lethal complication. Most frequently, this has been reported in patients infected with Plasmodium falciparum and Plasmodium vivax, while other parasitic agents are less likely to be the cause.We report a 29-year-old British Caucasian, who after returning from a business trip in Democratic Republic Congo was diagnosed with tertian malaria caused by Plasmodium ovale.During his in-patient stay, the patient suffered a splenic rupture requiring immediate surgical intervention and splenectomy. Following this surgical intervention, there was an uneventful recovery, and the patient was discharged in a good general condition.

DNA Cloning of Plasmodium falciparum Circumsporozoite Gene: Amino Acid Sequence of Repetitive Epitope

NASA Astrophysics Data System (ADS)

Enea, Vincenzo; Ellis, Joan; Zavala, Fidel; Arnot, David E.; Asavanich, Achara; Masuda, Aoi; Quakyi, Isabella; Nussenzweig, Ruth S.

1984-08-01

A clone of complementary DNA encoding the circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum has been isolated by screening an Escherichia coli complementary DNA library with a monoclonal antibody to the CS protein. The DNA sequence of the complementary DNA insert encodes a four-amino acid sequence: proline-asparagine-alanine-asparagine, tandemly repeated 23 times. The CS β -lactamase fusion protein specifically binds monoclonal antibodies to the CS protein and inhibits the binding of these antibodies to native Plasmodium falciparum CS protein. These findings provide a basis for the development of a vaccine against Plasmodium falciparum malaria.

Structure, Function and Inhibition of the Phosphoethanolamine Methyltransferases of the Human Malaria Parasites Plasmodium vivax and Plasmodium knowlesi

DOE PAGES

Garg, Aprajita; Lukk, Tiit; Kumar, Vidya; ...

2015-03-12

Phosphoethanolamine methyltransferases (PMTs) catalyze the three-step methylation of phosphoethanolamine to form phosphocholine, a critical step in the synthesis of phosphatidylcholine in a select number of eukaryotes including human malaria parasites, nematodes and plants. Genetic studies in the malaria parasite Plasmodium falciparum have shown that the methyltransferase PfPMT plays a critical function in parasite development and differentiation. The presence of PMT orthologs in other malaria parasites that infect humans and their absence in mammals make them ideal targets for the development of selective antimalarials with broad specificity against different Plasmodium species. Here we describe the X-ray structures and biochemical properties ofmore » PMT orthologs from Plasmodium vivax and Plasmodium knowlesi and show that both enzymes are inhibited by amodiaquine and NSC158011, two drugs with potent antimalarial activity. Metabolic studies in a yeast mutant that relies on PkPMT or PvPMT for survival demonstrated that these compounds inhibit phosphatidylcholine biosynthesis from ethanolamine. Our structural and functional data provide insights into the mechanism of catalysis and inhibition of PMT enzymes and set the stage for a better design of more specific and selective antimalarial drugs.« less

Th1-like Plasmodium-Specific Memory CD4+ T Cells Support Humoral Immunity.

PubMed

Zander, Ryan A; Vijay, Rahul; Pack, Angela D; Guthmiller, Jenna J; Graham, Amy C; Lindner, Scott E; Vaughan, Ashley M; Kappe, Stefan H I; Butler, Noah S

2017-11-14

Effector T cells exhibiting features of either T helper 1 (Th1) or T follicular helper (Tfh) populations are essential to control experimental Plasmodium infection and are believed to be critical for resistance to clinical malaria. To determine whether Plasmodium-specific Th1- and Tfh-like effector cells generate memory populations that contribute to protection, we developed transgenic parasites that enable high-resolution study of anti-malarial memory CD4 T cells in experimental models. We found that populations of both Th1- and Tfh-like Plasmodium-specific memory CD4 T cells persist. Unexpectedly, Th1-like memory cells exhibit phenotypic and functional features of Tfh cells during recall and provide potent B cell help and protection following transfer, characteristics that are enhanced following ligation of the T cell co-stimulatory receptor OX40. Our findings delineate critical functional attributes of Plasmodium-specific memory CD4 T cells and identify a host-specific factor that can be targeted to improve resolution of acute malaria and provide durable, long-term protection against Plasmodium parasite re-exposure. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Structure, Function and Inhibition of the Phosphoethanolamine Methyltransferases of the Human Malaria Parasites Plasmodium vivax and Plasmodium knowlesi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garg, Aprajita; Lukk, Tiit; Kumar, Vidya

Phosphoethanolamine methyltransferases (PMTs) catalyze the three-step methylation of phosphoethanolamine to form phosphocholine, a critical step in the synthesis of phosphatidylcholine in a select number of eukaryotes including human malaria parasites, nematodes and plants. Genetic studies in the malaria parasite Plasmodium falciparum have shown that the methyltransferase PfPMT plays a critical function in parasite development and differentiation. The presence of PMT orthologs in other malaria parasites that infect humans and their absence in mammals make them ideal targets for the development of selective antimalarials with broad specificity against different Plasmodium species. Here we describe the X-ray structures and biochemical properties ofmore » PMT orthologs from Plasmodium vivax and Plasmodium knowlesi and show that both enzymes are inhibited by amodiaquine and NSC158011, two drugs with potent antimalarial activity. Metabolic studies in a yeast mutant that relies on PkPMT or PvPMT for survival demonstrated that these compounds inhibit phosphatidylcholine biosynthesis from ethanolamine. Our structural and functional data provide insights into the mechanism of catalysis and inhibition of PMT enzymes and set the stage for a better design of more specific and selective antimalarial drugs.« less

Detection of avian malaria (Plasmodium spp.) in native land birds of American Samoa

USGS Publications Warehouse

Jarvi, S.I.; Farias, M.E.M.; Baker, H.; Freifeld, H.B.; Baker, P.E.; Van Gelder, E.; Massey, J.G.; Atkinson, C.T.

2003-01-01

This study documents the presence of Plasmodium spp. in landbirds of central Polynesia. Blood samples collected from eight native and introduced species from the island of Tutuila, American Samoa were evaluated for the presence of Plasmodium spp. by nested rDNA PCR, serology and/or microscopy. A total of 111/188 birds (59%) screened by nested PCR were positive. Detection of Plasmodium spp. was verified by nucleotide sequence comparisons of partial 18S ribosomal RNA and TRAP (thrombospondin-related anonymous protein) genes using phylogenetic analyses. All samples screened by immunoblot to detect antibodies that cross-react with Hawaiian isolates of Plasmodium relictum (153) were negative. Lack of cross-reactivity is probably due to antigenic differences between the Hawaiian and Samoan Plasmodium isolates. Similarly, all samples examined by microscopy (214) were negative. The fact that malaria is present, but not detectable by blood smear evaluation is consistent with low peripheral parasitemia characteristic of chronic infections. High prevalence of apparently chronic infections, the relative stability of the native land bird communities, and the presence of mosquito vectors which are considered endemic and capable of transmitting avian Plasmodia, suggest that these parasites are indigenous to Samoa and have a long coevolutionary history with their hosts.

Antimalarial efficacy of MMV390048, an inhibitor of Plasmodium phosphatidylinositol 4-kinase.

PubMed

Paquet, Tanya; Le Manach, Claire; Cabrera, Diego González; Younis, Yassir; Henrich, Philipp P; Abraham, Tara S; Lee, Marcus C S; Basak, Rajshekhar; Ghidelli-Disse, Sonja; Lafuente-Monasterio, María José; Bantscheff, Marcus; Ruecker, Andrea; Blagborough, Andrew M; Zakutansky, Sara E; Zeeman, Anne-Marie; White, Karen L; Shackleford, David M; Mannila, Janne; Morizzi, Julia; Scheurer, Christian; Angulo-Barturen, Iñigo; Martínez, María Santos; Ferrer, Santiago; Sanz, Laura María; Gamo, Francisco Javier; Reader, Janette; Botha, Mariette; Dechering, Koen J; Sauerwein, Robert W; Tungtaeng, Anchalee; Vanachayangkul, Pattaraporn; Lim, Chek Shik; Burrows, Jeremy; Witty, Michael J; Marsh, Kennan C; Bodenreider, Christophe; Rochford, Rosemary; Solapure, Suresh M; Jiménez-Díaz, María Belén; Wittlin, Sergio; Charman, Susan A; Donini, Cristina; Campo, Brice; Birkholtz, Lyn-Marie; Hanson, Kirsten K; Drewes, Gerard; Kocken, Clemens H M; Delves, Michael J; Leroy, Didier; Fidock, David A; Waterson, David; Street, Leslie J; Chibale, Kelly

2017-04-26

As part of the global effort toward malaria eradication, phenotypic whole-cell screening revealed the 2-aminopyridine class of small molecules as a good starting point to develop new antimalarial drugs. Stemming from this series, we found that the derivative, MMV390048, lacked cross-resistance with current drugs used to treat malaria. This compound was efficacious against all Plasmodium life cycle stages, apart from late hypnozoites in the liver. Efficacy was shown in the humanized Plasmodium falciparum mouse model, and modest reductions in mouse-to-mouse transmission were achieved in the Plasmodium berghei mouse model. Experiments in monkeys revealed the ability of MMV390048 to be used for full chemoprotection. Although MMV390048 was not able to eliminate liver hypnozoites, it delayed relapse in a Plasmodium cynomolgi monkey model. Both genomic and chemoproteomic studies identified a kinase of the Plasmodium parasite, phosphatidylinositol 4-kinase, as the molecular target of MMV390048. The ability of MMV390048 to block all life cycle stages of the malaria parasite suggests that this compound should be further developed and may contribute to malaria control and eradication as part of a single-dose combination treatment. Copyright © 2017, American Association for the Advancement of Science.

Helminth Parasites Alter Protection against Plasmodium Infection

PubMed Central

Salazar-Castañon, Víctor H.; Legorreta-Herrera, Martha

2014-01-01

More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response. PMID:25276830

Wolbachia increases susceptibility to Plasmodium infection in a natural system.

PubMed

Zélé, F; Nicot, A; Berthomieu, A; Weill, M; Duron, O; Rivero, A

2014-03-22

Current views about the impact of Wolbachia on Plasmodium infections are almost entirely based on data regarding artificially transfected mosquitoes. This work has shown that Wolbachia reduces the intensity of Plasmodium infections in mosquitoes, raising the exciting possibility of using Wolbachia to control or limit the spread of malaria. Whether natural Wolbachia infections have the same parasite-inhibiting properties is not yet clear. Wolbachia-mosquito combinations with a long evolutionary history are, however, key for understanding what may happen with Wolbachia-transfected mosquitoes after several generations of coevolution. We investigate this issue using an entirely natural mosquito-Wolbachia-Plasmodium combination. In contrast to most previous studies, which have been centred on the quantification of the midgut stages of Plasmodium, we obtain a measurement of parasitaemia that relates directly to transmission by following infections to the salivary gland stages. We show that Wolbachia increases the susceptibility of Culex pipiens mosquitoes to Plasmodium relictum, significantly increasing the prevalence of salivary gland stage infections. This effect is independent of the density of Wolbachia in the mosquito. These results suggest that naturally Wolbachia-infected mosquitoes may, in fact, be better vectors of malaria than Wolbachia-free ones.

Evaluation of the Clearview® Malaria pLDH Malaria Rapid Diagnostic Test in a non-endemic setting.

PubMed

Houzé, Sandrine; Hubert, Véronique; Cohen, Dorit Pessler; Rivetz, Baruch; Le Bras, Jacques

2011-09-27

Malaria Rapid Diagnostic Tests (RDTs) are widely used to diagnose malaria. The present study evaluated a new RDT, the Clearview® Malaria pLDH test targeting the pan-Plasmodium antigen lactate dehydrogenase (pLDH). The Clearview® Malaria pLDH test was evaluated on fresh samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included samples were Plasmodium falciparum (139), Plasmodium vivax (22), Plasmodium ovale (20), Plasmodium malariae (7), and 102 negative. Overall sensitivity for the detection of Plasmodium spp was 93.2%. For P. falciparum, the sensitivity was 98.6%; for P. vivax, P. ovale and P. malariae, overall sensitivities were 90.9%, 60.0% and 85.7% respectively. For P. falciparum and for P. vivax, the sensitivities increased to 100% at parasite densities above 100/μl. The specificity was 100%. The test was easily to perform and the result was stable for at least 1 hour. The Clearview® Malaria pLDH was efficient for the diagnosis of malaria. The test was very sensitive for P. falciparum and P. vivax detection. The sensitivities for P. ovale and P. malariae were better than other RDTs.

Evaluation of FRET real-time PCR assay for rapid detection and differentiation of Plasmodium species in returning travellers and migrants

PubMed Central

Safeukui, Innocent; Millet, Pascal; Boucher, Sébastien; Melinard, Laurence; Fregeville, Frédéric; Receveur, Marie-Catherine; Pistone, Thierry; Fialon, Pierre; Vincendeau, Philippe; Fleury, Hervé; Malvy, Denis

2008-01-01

Background A simple real-time PCR assay using one set of primer and probe for rapid, sensitive and quantitative detection of Plasmodium species, with simultaneous differentiation of Plasmodium falciparum from the three other Plasmodium species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae) in febrile returning travellers and migrants was developed and evaluated. Methods Consensus primers were used to amplify a species-specific region of the multicopy 18S rRNA gene, and fluorescence resonance energy transfer hybridization probes were used for detection in a LightCycler platform (Roche). The anchor probe sequence was designed to be perfect matches to the 18S rRNA gene of the fourth Plasmodium species, while the acceptor probe sequence was designed for P. falciparum over a region containing one mismatched, which allowed differentiation of the three other Plasmodium species. The performance characteristics of the real-time PCR assay were compared with those of conventional PCR and microscopy-based diagnosis from 119 individuals with a suspected clinical diagnostic of imported malaria. Results Blood samples with parasite densities less than 0.01% were all detected, and analytical sensitivity was 0.5 parasite per PCR reaction. The melt curve means Tms (standard deviation) in clinical isolates were 60.5°C (0.6°C) for P. falciparum infection and 64.6°C (1.8°C) for non-P. falciparum species. These Tms values of the P. falciparum or non-P. falciparum species did not vary with the geographic origin of the parasite. The real-time PCR results correlated with conventional PCR using both genus-specific (Kappa coefficient: 0.95, 95% confidence interval: 0.9 – 1) or P. falciparum-specific (0.91, 0.8 – 1) primers, or with the microscopy results (0.70, 0.6 – 0.8). The real-time assay was 100% sensitive and specific for differentiation of P. falciparum to non-P. falciparum species, compared with conventional PCR or microscopy. The real-time PCR assay can also detect individuals with mixed infections (P. falciparum and non-P. falciparum sp.) in the same sample. Conclusion This real-time PCR assay with melting curve analysis is rapid, and specific for the detection and differentiation of P. falciparum to other Plasmodium species. The suitability for routine use of this assay in clinical diagnostic laboratories is discussed. PMID:18442362

The detection of cryptic Plasmodium infection among villagers in Attapeu province, Lao PDR

PubMed Central

Khattignavong, Phonepadith; Soundala, Pheovaly; Lorphachan, Lavy; Matsumoto-Takahashi, Emilie; Strobel, Michel; Reinharz, Daniel; Phommasansack, Manisack; Hongvanthong, Bouasy; Brey, Paul T.

2017-01-01

Background Although the malaria burden in the Lao PDR has gradually decreased, the elimination of malaria by 2030 presents many challenges. Microscopy and malaria rapid diagnostic tests (RDTs) are used to diagnose malaria in the Lao PDR; however, some studies have reported the prevalence of sub-microscopic Plasmodium infections or asymptomatic Plasmodium carriers in endemic areas. Thus, highly sensitive detection methods are needed to understand the precise malaria situation in these areas. Methodology/Principal findings A cross-sectional malaria field survey was conducted in 3 highly endemic malaria districts (Xaysetha, Sanamxay, Phouvong) in Attapeu province, Lao PDR in 2015, to investigate the precise malaria endemicity in the area; 719 volunteers from these villages participated in the survey. Microscopy, RDTs and a real-time nested PCR were used to detect Plasmodium infections and their results were compared. A questionnaire survey of all participants was also conducted to estimate risk factors of Plasmodium infection. Numbers of infections detected by the three methods were microscopy: P. falciparum (n = 1), P. vivax (n = 2); RDTs: P. falciparum (n = 2), P. vivax (n = 3); PCR: Plasmodium (n = 47; P. falciparum [n = 4], P. vivax [n = 41], mixed infection [n = 2]; 6.5%, 47/719). Using PCR as a reference, the sensitivity and specificity of microscopy were 33.3% and 100.0%, respectively, for detecting P. falciparum infection, and 7.0% and 100.0%, for detecting P. vivax infection. Among the 47 participants with parasitemia, only one had a fever (≥37.5°C) and 31 (66.0%) were adult males. Risk factors of Plasmodium infection were males and soldiers, whereas a risk factor of asymptomatic Plasmodium infection was a history of ≥3 malaria episodes. Conclusions/Significance There were many asymptomatic Plasmodium carriers in the study areas of Attapeu province in 2015. Adult males, probably soldiers, were at high risk for malaria infection. P. vivax, the dominant species, accounted for 87.2% of the Plasmodium infections among the participants. To achieve malaria elimination in the Lao PDR, highly sensitive diagnostic tests, including PCR-based diagnostic methods should be used, and plans targeting high-risk populations and elimination of P. vivax should be designed and implemented. PMID:29261647

Four human Plasmodium species quantification using droplet digital PCR.

PubMed

Srisutham, Suttipat; Saralamba, Naowarat; Malleret, Benoit; Rénia, Laurent; Dondorp, Arjen M; Imwong, Mallika

2017-01-01

Droplet digital polymerase chain reaction (ddPCR) is a partial PCR based on water-oil emulsion droplet technology. It is a highly sensitive method for detecting and delineating minor alleles from complex backgrounds and provides absolute quantification of DNA targets. The ddPCR technology has been applied for detection of many pathogens. Here the sensitive assay utilizing ddPCR for detection and quantification of Plasmodium species was investigated. The assay was developed for two levels of detection, genus specific for all Plasmodium species and for specific Plasmodium species detection. The ddPCR assay was developed based on primers and probes specific to the Plasmodium genus 18S rRNA gene. Using ddPCR for ultra-sensitive P. falciparum assessment, the lower level of detection from concentrated DNA obtained from a high volume (1 mL) blood sample was 11 parasites/mL. For species identification, in particular for samples with mixed infections, a duplex reaction was developed for detection and quantification P. falciparum/ P. vivax and P. malariae/ P. ovale. Amplification of each Plasmodium species in the duplex reaction showed equal sensitivity to singleplex single species detection. The duplex ddPCR assay had higher sensitivity to identify minor species in 32 subpatent parasitaemia samples from Cambodia, and performed better than real-time PCR. The ddPCR assay shows high sensitivity to assess very low parasitaemia of all human Plasmodium species. This provides a useful research tool for studying the role of the asymptomatic parasite reservoir for transmission in regions aiming for malaria elimination.

Infection with Wolbachia protects mosquitoes against Plasmodium-induced mortality in a natural system.

PubMed

Zélé, F; Nicot, A; Duron, O; Rivero, A

2012-07-01

In recent years, there has been a shift in the one host-one parasite paradigm with the realization that, in the field, most hosts are coinfected with multiple parasites. Coinfections are particularly relevant when the host is a vector of diseases, because multiple infections can have drastic consequences for parasite transmission at both the ecological and evolutionary timescales. Wolbachia pipientis is the most common parasitic microorganism in insects, and as such, it is of special interest for understanding the role of coinfections in the outcome of parasite infections. Here, we investigate whether Wolbachia can modulate the effect of Plasmodium on what is, arguably, the most important component of the vectorial capacity of mosquitoes: their longevity. For this purpose, and in contrast to recent studies that have focused on mosquito-Plasmodium and/or mosquito-Wolbachia combinations not found in nature, we work on a Wolbachia-mosquito-Plasmodium triad with a common evolutionary history. Our results show that Wolbachia protects mosquitoes from Plasmodium-induced mortality. The results are consistent across two different strains of Wolbachia and repeatable across two different experimental blocks. To our knowledge, this is the first time that such an effect has been shown for Plasmodium-infected mosquitoes and, in particular, in a natural Wolbachia-host combination. We discuss different mechanistic and evolutionary explanations for these results as well as their consequences for Plasmodium transmission. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Simple Molecular Methods for Early Detection of Chloroquine Drug Resistance in Plasmodium vivax and Plasmodium falciparum

PubMed Central

Singh, Raksha; Urhehar, Anant Dattatraya

2016-01-01

Introduction Malaria is a human disease of which causes high morbidity and mortality. In Plasmodium falciparum malaria, the resistance to antimalarial drugs, especially chloroquine (CQ) is one of the paramount factors contributing to the global increase in morbidity and mortality, due to malaria. Hence, there is a need for detection of chloroquine drug resistance genes i.e., pfcrt-o (Plasmodium falciparum chloroquine resistance transporter-o) and pfmdr-1 (Plasmodium falciparum multidrug resistance-1) of P. falciparum and pvcrt-o (Plasmodium vivax chloroquine resistance transporter-o) and pvmdr-1 (Plasmodium vivax multidrug resistance-1) of P. vivax by using molecular methods to prevent mortality in malarial cases. Aim To standardize chloroquine drug sensitivity testing by molecular method so as to provide reports of chloroquine within 6-8 hours to physicians for better treatment. Materials and Methods This study was conducted over a period of one year from January to December 2014. A Total of 300 blood samples were collected from malaria suspected patient attending MGM Hospital, Kamothe, Navi Mumbai, India. Out of 300 blood samples, 44 were malaria positive as assessed by Thick and Thin blood smear stained, by Leishman’s method and examination with light microscope. Chloroquine drug sensitivity testing was performed using WHO III plate method (micro test). Nested PCR was done for detection of pfcrt-o and pfmdr-1 for P. falciparum and pvcrt-o, pvmdr-1 genes for P. vivax. Results Total 44 samples were included in this study, out of which 22 samples confirmed for Plasmodium falciparum and 22 samples confirmed for Plasmodium vivax. Out of 22 P. falciparum 15 (68.18%) samples were chloroquine resistant. P. vivax showed chloroquine resistance to 5 samples (22.73%) by method similar to WHO III plate method (micro test) and nested PCR. Conclusion Drug resistance testing by molecular methods is useful for early detection of antimalarial drug resistance. pfmdr-1 along with pfcrt-o can be used as biomarker for chloroquine drug resistance in P. falciparum and pvmdr-1 along with pvcrt-o for P. vivax. PMID:27630842

A systematic review of transfusion-transmitted malaria in non-endemic areas.

PubMed

Verra, Federica; Angheben, Andrea; Martello, Elisa; Giorli, Giovanni; Perandin, Francesca; Bisoffi, Zeno

2018-01-16

Transfusion-transmitted malaria (TTM) is an accidental Plasmodium infection caused by whole blood or a blood component transfusion from a malaria infected donor to a recipient. Infected blood transfusions directly release malaria parasites in the recipient's bloodstream triggering the development of high risk complications, and potentially leading to a fatal outcome especially in individuals with no previous exposure to malaria or in immuno-compromised patients. A systematic review was conducted on TTM case reports in non-endemic areas to describe the epidemiological characteristics of blood donors and recipients. Relevant articles were retrieved from Pubmed, EMBASE, Scopus, and LILACS. From each selected study the following data were extracted: study area, gender and age of blood donor and recipient, blood component associated with TTM, Plasmodium species, malaria diagnostic method employed, blood donor screening method, incubation period between the infected transfusion and the onset of clinical symptoms in the recipient, time elapsed between the clinical symptoms and the diagnosis of malaria, infection outcome, country of origin of the blood donor and time of the last potential malaria exposure. Plasmodium species were detected in 100 TTM case reports with a different frequency: 45% Plasmodium falciparum, 30% Plasmodium malariae, 16% Plasmodium vivax, 4% Plasmodium ovale, 2% Plasmodium knowlesi, 1% mixed infection P. falciparum/P. malariae. The majority of fatal outcomes (11/45) was caused by P. falciparum whilst the other fatalities occurred in individuals infected by P. malariae (2/30) and P. ovale (1/4). However, non P. falciparum fatalities were not attributed directly to malaria. The incubation time for all Plasmodium species TTM case reports was longer than what expected in natural infections. This difference was statistically significant for P. malariae (p = 0.006). A longer incubation time in the recipient together with a chronic infection at low parasite density of the donor makes P. malariae a subtle but not negligible risk for blood safety aside from P. falciparum. TTM risk needs to be taken into account in order to enhance the safety of the blood supply chain from donors to recipients by means of appropriate diagnostic tools.

Plasmodium vivax aldolase-specific monoclonal antibodies and its application in clinical diagnosis of malaria infections in China.

PubMed

Dzakah, Emmanuel E; Kang, Keren; Ni, Chao; Wang, Hong; Wu, Peidian; Tang, Shixing; Wang, Jihua; Wang, Jufang; Wang, Xiaoning

2013-06-12

Most rapid diagnostic tests (RDTs) currently used for malaria diagnosis cannot distinguish the various Plasmodium infections. The development of a Plasmodium vivax specific RDTs with high sensitivity to sufficiently differentiate the two most common Plasmodium infections would be very crucial for disease treatment and control. Plasmodium vivax aldolase gene (PvALDO) was amplified from the extracted genomic DNA and constructed into pET30a vector. Plasmodium vivax aldolase protein was successfully expressed in Escherichia coli in soluble form and the overall purity was over 95% after one-step affinity chromatography purification. The purified products were used for the immunization of mice and rabbits. Rabbit polyclonal antibodies generated were deployed to develop a novel antibody-capture ELISA for hybridoma screening. Three PvALDO specific mAbs (14C7, 15F1 and 5H7) with high affinities were selected and used in immunochromatographic test strips. Clinical blood samples (n=190) collected from Yunnan (China) were used for evaluation and the RDT's sensitivity for P. vivax was 98.33% (95% Confidence Interval (CI): 91.03% to 99.72%) compared with microscopic examination. There was specificity of 99.23% (95% CI: 95.77% to 99.87%) for P. vivax. Only one Plasmodium falciparum sample was detected among the P. falciparum samples (n=20). All Plasmodium malariae samples (n=2) as well as healthy uninfected samples (n=108) were negative. Overall performance of this RDT was excellent with positive predictive value (PPV) and negative predictive value (NPV) of 98.33% and 99.23%, respectively, at 95% CI and a very good correlation with microscopic observations (kappa value, K=0.9757). Test strips show high sensitivity even at 6.25 ng/ml of recombinant P. vivax aldolase (rPvALDO). This study further elucidates the possibility of developing aldolase-specific RDTs which can differentiate the different Plasmodium infections and improve accurate diagnosis of malaria. This RDT could adequately differentiate between P. vivax and P. falciparum infections. The novel mAb screening method developed here could find application in the screening of highly specific antibodies against other antigens.

Plasmodium vivax aldolase-specific monoclonal antibodies and its application in clinical diagnosis of malaria infections in China

PubMed Central

2013-01-01

Background Most rapid diagnostic tests (RDTs) currently used for malaria diagnosis cannot distinguish the various Plasmodium infections. The development of a Plasmodium vivax specific RDTs with high sensitivity to sufficiently differentiate the two most common Plasmodium infections would be very crucial for disease treatment and control. Method Plasmodium vivax aldolase gene (PvALDO) was amplified from the extracted genomic DNA and constructed into pET30a vector. Plasmodium vivax aldolase protein was successfully expressed in Escherichia coli in soluble form and the overall purity was over 95% after one-step affinity chromatography purification. The purified products were used for the immunization of mice and rabbits. Rabbit polyclonal antibodies generated were deployed to develop a novel antibody-capture ELISA for hybridoma screening. Results Three PvALDO specific mAbs (14C7, 15F1 and 5H7) with high affinities were selected and used in immunochromatographic test strips. Clinical blood samples (n=190) collected from Yunnan (China) were used for evaluation and the RDT’s sensitivity for P. vivax was 98.33% (95% Confidence Interval (CI): 91.03% to 99.72%) compared with microscopic examination. There was specificity of 99.23% (95% CI: 95.77% to 99.87%) for P. vivax. Only one Plasmodium falciparum sample was detected among the P. falciparum samples (n=20). All Plasmodium malariae samples (n=2) as well as healthy uninfected samples (n=108) were negative. Overall performance of this RDT was excellent with positive predictive value (PPV) and negative predictive value (NPV) of 98.33% and 99.23%, respectively, at 95% CI and a very good correlation with microscopic observations (kappa value, K=0.9757). Test strips show high sensitivity even at 6.25 ng/ml of recombinant P. vivax aldolase (rPvALDO). Conclusion This study further elucidates the possibility of developing aldolase-specific RDTs which can differentiate the different Plasmodium infections and improve accurate diagnosis of malaria. This RDT could adequately differentiate between P. vivax and P. falciparum infections. The novel mAb screening method developed here could find application in the screening of highly specific antibodies against other antigens. PMID:23758950

Plasmodium knowlesi in travellers, update 2014.

PubMed

Müller, Mattia; Schlagenhauf, Patricia

2014-05-01

Since the initial discovery of Plasmodium knowlesi in Malaysia, cases have been reported from several neighbouring countries. Tourism has also resulted in an increasing number of cases diagnosed in Europe, America, and Oceania. In this review we focus on the risk of the travel-associated acquisition of P. knowlesi malaria. A search of the literature in PubMed was carried out to identify articles and literature on the distribution of P. knowlesi infections in Southeast Asia and details of its acquisition and importation by travellers to other continents. The cut-off date for the search was December 1, 2013. Search words used were: "Plasmodium knowlesi", "Plasmodium knowlesi infections", "Plasmodium knowlesi travellers", "Plasmodium knowlesi prevalence", "Plasmodium knowlesi host", "Plasmodium knowlesi vector" "Plasmodium knowlesi RDT", and "Plasmodium knowlesi Malaysia". Traveller numbers to Malaysia were obtained from the Tourism Malaysia website. A total of 103 articles were found. Using a selection of these and others identified from the reference lists of the papers, we based our review on a total of 66 articles. P. knowlesi malaria appears to be the most common malaria species in Malaysian Borneo and is also widely distributed on the Malaysian mainland. Furthermore, locally transmitted cases of P. knowlesi malaria have been reported in Thailand, the Philippines, Vietnam, Singapore, Myanmar, Indonesian Borneo, and Cambodia. Two cases have been reported from non-endemic countries in Asia (Japan and Taiwan) in people with a history of travel to Malaysia and the Philippines. Twelve cases were imported to their home countries by travellers from other continents: two from the USA, two from the Netherlands, two from Germany, and one each from Spain, France, Sweden, Finland, Australia, and New Zealand. In most cases, the infection was associated with a trip to or near forested areas. The symptoms were fever (n=12), headache (n=6), chills (n=6), nausea (n=4), myalgia (n=3), back pain (n=3), abdominal problems (n=1), anorexia (n=2), fatigue (n=2), malaise (n=1), arthralgia (n=1), sore throat (n=1) vomiting (n=2), and jaundice (n=1). All patients were treated successfully with currently available antimalaria treatments. The identification of the pathogen by microscopy can be problematic due to the morphological similarity of P. knowlesi to Plasmodium malariae. P. knowlesi appears to be a threat not only to the local population in Malaysia, but also to the estimated 25 million annual tourists and occupational travellers to Malaysia, especially those who visit rural, forested areas of the country. The P. knowlesi risk is not limited to Malaysia, and travellers from Southeast Asia presenting with possible malaria should be considered for a diagnostic work-up that includes P. knowlesi. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Development of a Photo-Cross-Linkable Diaminoquinazoline Inhibitor for Target Identification in Plasmodium falciparum.

PubMed

Lubin, Alexandra S; Rueda-Zubiaurre, Ainoa; Matthews, Holly; Baumann, Hella; Fisher, Fabio R; Morales-Sanfrutos, Julia; Hadavizadeh, Kate S; Nardella, Flore; Tate, Edward W; Baum, Jake; Scherf, Artur; Fuchter, Matthew J

2018-04-13

Diaminoquinazolines represent a privileged scaffold for antimalarial discovery, including use as putative Plasmodium histone lysine methyltransferase inhibitors. Despite this, robust evidence for their molecular targets is lacking. Here we report the design and development of a small-molecule photo-cross-linkable probe to investigate the targets of our diaminoquinazoline series. We demonstrate the effectiveness of our designed probe for photoaffinity labeling of Plasmodium lysates and identify similarities between the target profiles of the probe and the representative diaminoquinazoline BIX-01294. Initial pull-down proteomics experiments identified 104 proteins from different classes, many of which are essential, highlighting the suitability of the developed probe as a valuable tool for target identification in Plasmodium falciparum.

Emergence and transitions of dynamic patterns of thickness oscillation of the plasmodium of the true slime mold Physarum polycephalum

NASA Astrophysics Data System (ADS)

Takagi, Seiji; Ueda, Tetsuo

2008-03-01

The emergence and transitions of various spatiotemporal patterns of thickness oscillation were studied in the freshly isolated protoplasm of the Physarum plasmodium. New patterns, such as standing waves, and chaotic and rotating spirals, developed successively before the well-documented synchronous pattern appeared. There was also a spontaneous opposite transition from synchrony to chaotic and rotating spirals. Rotating spiral waves were observed in the large migrating plasmodium, where the vein structures were being destroyed. Thus, the Physarum plasmodium exhibits versatile patterns, which are generally expected in coupled oscillator systems. This paper discusses the physiological roles of spatiotemporal patterns, comparing them with other biological systems.

Pretreatment with Cry1Ac Protoxin Modulates the Immune Response, and Increases the Survival of Plasmodium-Infected CBA/Ca Mice

PubMed Central

Legorreta-Herrera, Martha; Oviedo Meza, Rodrigo; Moreno-Fierros, Leticia

2010-01-01

Malaria is a major global health problem that kills 1-2 million people each year. Despite exhaustive research, naturally acquired immunity is poorly understood. Cry1A proteins are potent immunogens with adjuvant properties and are able to induce strong cellular and humoral responses. In fact, it has been shown that administration of Cry1Ac protoxin alone or with amoebic lysates induces protection against the lethal infection caused by the protozoa Naegleria fowleri. In this work, we studied whether Cry1Ac is able to activate the innate immune response to induce protection against Plasmodium berghei ANKA (lethal) and P. chabaudi AS (nonlethal) parasites in CBA/Ca mice. Treatment with Cry1Ac induced protection against both Plasmodium species in terms of reduced parasitaemia, longer survival time, modulation of pro- and anti-inflammatory cytokines, and increased levels of specific antibodies against Plasmodium. Understanding how to boost innate immunity to Plasmodium infection should lead to immunologically based intervention strategies. PMID:20300584

Enlightening the malaria parasite life cycle: bioluminescent Plasmodium in fundamental and applied research.

PubMed

Siciliano, Giulia; Alano, Pietro

2015-01-01

The unicellular protozoan parasites of the genus Plasmodium impose on human health worldwide the enormous burden of malaria. The possibility to genetically modify several species of malaria parasites represented a major advance in the possibility to elucidate their biology and is now turning laboratory lines of transgenic Plasmodium into precious weapons to fight malaria. Amongst the various genetically modified plasmodia, transgenic parasite lines expressing bioluminescent reporters have been essential to unveil mechanisms of parasite gene expression and to develop in vivo imaging approaches in mouse malaria models. Mainly the human malaria parasite Plasmodium falciparum and the rodent parasite P. berghei have been engineered to express bioluminescent reporters in almost all the developmental stages of the parasite along its complex life cycle between the insect and the vertebrate hosts. Plasmodium lines expressing conventional and improved luciferase reporters are now gaining a central role to develop cell based assays in the much needed search of new antimalarial drugs and to open innovative approaches for both fundamental and applied research in malaria.

Molecular machinery of signal transduction and cell cycle regulation in Plasmodium.

PubMed

Koyama, Fernanda C; Chakrabarti, Debopam; Garcia, Célia R S

2009-05-01

The regulation of the Plasmodium cell cycle is not understood. Although the Plasmodium falciparum genome is completely sequenced, about 60% of the predicted proteins share little or no sequence similarity with other eukaryotes. This feature impairs the identification of important proteins participating in the regulation of the cell cycle. There are several open questions that concern cell cycle progression in malaria parasites, including the mechanism by which multiple nuclear divisions is controlled and how the cell cycle is managed in all phases of their complex life cycle. Cell cycle synchrony of the parasite population within the host, as well as the circadian rhythm of proliferation, are striking features of some Plasmodium species, the molecular basis of which remains to be elucidated. In this review we discuss the role of indole-related molecules as signals that modulate the cell cycle in Plasmodium and other eukaryotes, and we also consider the possible role of kinases in the signal transduction and in the responses it triggers.

Intra-specific diversity of Serratia marcescens in Anopheles mosquito midgut defines Plasmodium transmission capacity

PubMed Central

Bando, Hironori; Okado, Kiyoshi; Guelbeogo, Wamdaogo M.; Badolo, Athanase; Aonuma, Hiroka; Nelson, Bryce; Fukumoto, Shinya; Xuan, Xuenan; Sagnon, N'Fale; Kanuka, Hirotaka

2013-01-01

A critical stage in malaria transmission occurs in the Anopheles mosquito midgut, when the malaria parasite, Plasmodium, ingested with blood, first makes contact with the gut epithelial surface. To understand the response mechanisms within the midgut environment, including those influenced by resident microbiota against Plasmodium, we focus on a midgut bacteria species' intra-specific variation that confers diversity to the mosquito's competency for malaria transmission. Serratia marcescens isolated from either laboratory-reared mosquitoes or wild populations in Burkina Faso shows great phenotypic variation in its cellular and structural features. Importantly, this variation is directly correlated with its ability to inhibit Plasmodium development within the mosquito midgut. Furthermore, this anti-Plasmodium function conferred by Serratia marcescens requires increased expression of the flagellum biosynthetic pathway that is modulated by the motility master regulatory operon, flhDC. These findings point to new strategies for controlling malaria through genetic manipulation of midgut bacteria within the mosquito. PMID:23571408

Potentiation of Artemisinin Activity against Chloroquine-Resistant Plasmodium falciparum Strains by Using Heme Models

PubMed Central

Benoit-Vical, Françoise; Robert, Anne; Meunier, Bernard

1999-01-01

The influence of different metalloporphyrin derivatives on the antimalarial activity of artemisinin was studied with two chloroquine-resistant strains of Plasmodium falciparum (FcB1-Colombia and FcM29-Cameroon) cultured in human erythrocytes. This potentiation study indicates that the manganese complex of meso-tetrakis(4-sulfonatophenyl)porphyrin has a significant synergistic effect on the activity of artemisinin against both Plasmodium strains. PMID:10508044

Efficacy of Chloroquine as a first line agent in the treatment of uncomplicated malaria due to Plasmodium vivax in children and treatment practices in Pakistan: A Pilot study.

PubMed

Waqar, Talal; Khushdil, Arshad; Haque, Khalid

2016-01-01

To ascertain the efficacy of chloroquine as first line agent in treatment of uncomplicated malaria -caused by Plasmodium vivax in children---and to determine its current treatment practice in Pakistan. This pilot study was conducted at the Paediatrics Department of Combined Military Hospital (CMH), Lahore, Pakistan. Forty-eight children between six months and twelve years of age having positive blood film for Plasmodium vivax were included. They were treated with chloroquine as a drug of - choice. Efficacy of chloroquine was assessed by clinical response, absence of parasitaemia on day seven and twenty-eight after initiation of therapy. A survey was also conducted to determine the first line therapeutic choice of Paediatricians in the treatment of uncomplicated Plasmodium vivax malaria in children in Pakistan. The results showed 100% efficacy of chloroquine in treating uncomplicated malaria caused by Plasmodium vivax in children. Artemisin was preferred by 74.28% Paediatricians' in combination therapy as 1st line treatment. Guidelines proposed by Malaria Control Programme Pakistan (MCPP) in collaboration with World Health Organization (WHO) are comprehensive but not being adhered to. The recently reported resistance of Plasmodium vivax to artemisin should urge measures to implement WHO guidelines.

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

PubMed Central

Pimenta, Paulo FP; Orfano, Alessandra S; Bahia, Ana C; Duarte, Ana PM; Ríos-Velásquez, Claudia M; Melo, Fabrício F; Pessoa, Felipe AC; Oliveira, Giselle A; Campos, Keillen MM; Villegas, Luis Martínez; Rodrigues, Nilton Barnabé; Nacif-Pimenta, Rafael; Simões, Rejane C; Monteiro, Wuelton M; Amino, Rogerio; Traub-Cseko, Yara M; Lima, José BP; Barbosa, Maria GV; Lacerda, Marcus VG; Tadei, Wanderli P; Secundino, Nágila FC

2015-01-01

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence. PMID:25742262

Phylogenomic analyses of malaria parasites and evolution of their exported proteins

PubMed Central

2011-01-01

Background Plasmodium falciparum is the most malignant agent of human malaria. It belongs to the taxon Laverania, which includes other ape-infecting Plasmodium species. The origin of the Laverania is still debated. P. falciparum exports pathogenicity-related proteins into the host cell using the Plasmodium export element (PEXEL). Predictions based on the presence of a PEXEL motif suggest that more than 300 proteins are exported by P. falciparum, while there are many fewer exported proteins in non-Laverania. Results A whole-genome approach was applied to resolve the phylogeny of eight Plasmodium species and four outgroup taxa. By using 218 orthologous proteins we received unanimous support for a sister group position of Laverania and avian malaria parasites. This observation was corroborated by the analyses of 28 exported proteins with orthologs present in all Plasmodium species. Most interestingly, several deviations from the P. falciparum PEXEL motif were found to be present in the orthologous sequences of non-Laverania. Conclusion Our phylogenomic analyses strongly support the hypotheses that the Laverania have been founded by a single Plasmodium species switching from birds to African great apes or vice versa. The deviations from the canonical PEXEL motif in orthologs may explain the comparably low number of exported proteins that have been predicted in non-Laverania. PMID:21676252

Susceptibility to Plasmodium liver stage infection is altered by hepatocyte polyploidy.

PubMed

Austin, Laura S; Kaushansky, Alexis; Kappe, Stefan H I

2014-05-01

Plasmodium parasites infect hepatocytes of their mammalian hosts and undergo obligate liver stage development. The specific host cell attributes that are important for liver infection remain largely unknown. Several host signalling pathways are perturbed in infected hepatocytes, some of which are important in the generation of hepatocyte polyploidy. To test the functional consequence of polyploidy on liver infection, we infected hepatocytes with the rodent malaria parasite Plasmodium yoelii both in vitro and in vivo and examined the ploidy of infected and uninfected hepatocytes by flow cytometry. In both hepatoma cell lines and in the mouse liver, the fraction of polyploid cells was higher in the infected cell population than in the uninfected cell population. When the data were reanalysed by comparing the extent of Plasmodium infection within each ploidy subset, we found that infection rates were elevated in more highly polyploid cells and lower in diploid cells. Furthermore, we found that the parasite's preference for host cells with high ploidy is conserved among rodent malaria species and the human malaria parasite Plasmodium falciparum. This parasite preference for host cells of high ploidy cannot be explained by differences in hepatocyte size or DNA replication. We conclude that Plasmodium preferentially infects and develops in polyploid hepatocytes. © 2014 John Wiley & Sons Ltd.

Plasmodium knowlesi from archival blood films: Further evidence that human infections are widely distributed and not newly emergent in Malaysian Borneo

PubMed Central

Lee, Kim-Sung; Cox-Singh, Janet; Brooke, George; Matusop, Asmad; Singh, Balbir

2009-01-01

Human infections with Plasmodium knowlesi have been misdiagnosed by microscopy as Plasmodium malariae due to their morphological similarities. Although microscopy-identified P. malariae cases have been reported in the state of Sarawak (Malaysian Borno) as early as 1952, recent epidemiological studies suggest the absence of indigenous P. malariae infections. The present study aimed to determine the past incidence and distribution of P. knowlesi infections in the state of Sarawak based on archival blood films from patients diagnosed by microscopy as having P. malariae infections. Nested PCR assays were used to identify Plasmodium species in DNA extracted from 47 thick blood films collected in 1996 from patients in seven different divisions throughout the state of Sarawak. Plasmodium knowlesi DNA was detected in 35 (97.2%) of 36 blood films that were positive for Plasmodium DNA, with patients originating from all seven divisions. Only one sample was positive for P. malariae DNA. This study provides further evidence of the widespread distribution of human infections with P. knowlesi in Sarawak and its past occurrence. Taken together with data from previous studies, our findings suggest that P. knowlesi malaria is not a newly emergent disease in humans. PMID:19358848

An overview of malaria transmission from the perspective of Amazon Anopheles vectors.

PubMed

Pimenta, Paulo F P; Orfano, Alessandra S; Bahia, Ana C; Duarte, Ana P M; Ríos-Velásquez, Claudia M; Melo, Fabrício F; Pessoa, Felipe A C; Oliveira, Giselle A; Campos, Keillen M M; Villegas, Luis Martínez; Rodrigues, Nilton Barnabé; Nacif-Pimenta, Rafael; Simões, Rejane C; Monteiro, Wuelton M; Amino, Rogerio; Traub-Cseko, Yara M; Lima, José B P; Barbosa, Maria G V; Lacerda, Marcus V G

2015-02-01

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Anopheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.

Susceptibility to Plasmodium liver stage infection is altered by hepatocyte polyploidy

PubMed Central

Austin, Laura S.; Kaushansky, Alexis; Kappe, Stefan H.I.

2014-01-01

Summary Plasmodium parasites infect hepatocytes of their mammalian hosts and within undergo obligate liver stage development. The specific host cell attributes that are important for liver infection remain largely unknown. Several host signaling pathways are perturbed in infected hepatocytes, some of which are important in the generation of hepatocyte polyploidy. To test the functional consequence of polyploidy in liver infection, we infected hepatocytes with the rodent malaria parasite Plasmodium yoelii both in vitro and in vivo and examined the ploidy of infected and uninfected hepatocytes by flow cytometry. In both hepatoma cell lines and in the mouse liver, the fraction of polyploid cells was higher in the infected cell population than in the uninfected cell population. When the data were reanalyzed by comparing the extent of Plasmodium infection within each ploidy subset, we found that infection rates were elevated in more highly polyploid cells and lower in diploid cells. Furthermore, we found that the parasite’s preference for host cells with high ploidy is conserved among rodent malaria species and the human malaria parasite Plasmodium falciparum. This parasite preference for host cells of high ploidy cannot be explained by differences in hepatocyte size or DNA replication. We conclude that Plasmodium preferentially infects and develops in polyploid hepatocytes. PMID:24612025

Protein O-fucosylation in Plasmodium falciparum ensures efficient infection of mosquito and vertebrate hosts.

PubMed

Lopaticki, Sash; Yang, Annie S P; John, Alan; Scott, Nichollas E; Lingford, James P; O'Neill, Matthew T; Erickson, Sara M; McKenzie, Nicole C; Jennison, Charlie; Whitehead, Lachlan W; Douglas, Donna N; Kneteman, Norman M; Goddard-Borger, Ethan D; Boddey, Justin A

2017-09-15

O-glycosylation of the Plasmodium sporozoite surface proteins CSP and TRAP was recently identified, but the role of this modification in the parasite life cycle and its relevance to vaccine design remain unclear. Here, we identify the Plasmodium protein O-fucosyltransferase (POFUT2) responsible for O-glycosylating CSP and TRAP. Genetic disruption of POFUT2 in Plasmodium falciparum results in ookinetes that are attenuated for colonizing the mosquito midgut, an essential step in malaria transmission. Some POFUT2-deficient parasites mature into salivary gland sporozoites although they are impaired for gliding motility, cell traversal, hepatocyte invasion, and production of exoerythrocytic forms in humanized chimeric liver mice. These defects can be attributed to destabilization and incorrect trafficking of proteins bearing thrombospondin repeats (TSRs). Therefore, POFUT2 plays a similar role in malaria parasites to that in metazoans: it ensures the trafficking of Plasmodium TSR proteins as part of a non-canonical glycosylation-dependent endoplasmic reticulum protein quality control mechanism.The role of O-glycosylation in the malaria life cycle is largely unknown. Here, the authors identify a Plasmodium protein O-fucosyltransferase and show that it is important for normal trafficking of a subset of surface proteins, particularly CSP and TRAP, and efficient infection of mosquito and vertebrate hosts.

Long-term pathogenic response to Plasmodium relictum infection in Culex pipiens mosquito.

PubMed

Pigeault, Romain; Villa, Manon

2018-01-01

The transmission of Plasmodium within a vertebrate host population is strongly associated with the life history traits of its vector. Therefore the effect of malaria infection on mosquito fecundity and longevity has traditionally received a lot of attention. Several species of malaria parasites reduce mosquito fecundity, nevertheless almost all of the studies have focused only on the first gonotrophic cycle. Yet, during their lifetime, female mosquitoes go through several gonotrophic cycles, which raises the question of whether they are able to compensate the fecundity costs induced by the parasite. The impact of Plasmodium infection on female longevity is not so clear and has produced conflicting results. Here we measured the impact of Plasmodium relictum on its vector's longevity and fecundity during three consecutive gonotrophic cycles. In accordance with previous studies, we observed a negative impact of Plasmodium infection on mosquito (Culex pipiens) fecundity in the first gonotrophic cycle. Interestingly, despite having taken two subsequent uninfected blood meals, the negative impact of malaria parasite persisted. Nevertheless no impact of infection on mosquito longevity was observed. Our results are not in line with the hypothesis that the reduction of fecundity observed in infected mosquitoes is an adaptive strategy of Plasmodium to increase the longevity of its vector. We discuss the different underlying mechanisms that may explain our results.

Evaluation of the Clearview® malaria pLDH malaria rapid diagnostic test in a non-endemic setting

PubMed Central

2011-01-01

Background Malaria Rapid Diagnostic Tests (RDTs) are widely used to diagnose malaria. The present study evaluated a new RDT, the Clearview® Malaria pLDH test targeting the pan-Plasmodium antigen lactate dehydrogenase (pLDH). Methods The Clearview® Malaria pLDH test was evaluated on fresh samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included samples were Plasmodium falciparum (139), Plasmodium vivax (22), Plasmodium ovale (20), Plasmodium malariae (7), and 102 negative. Results Overall sensitivity for the detection of Plasmodium spp was 93.2%. For P. falciparum, the sensitivity was 98.6%; for P. vivax, P. ovale and P. malariae, overall sensitivities were 90.9%, 60.0% and 85.7% respectively. For P. falciparum and for P. vivax, the sensitivities increased to 100% at parasite densities above 100/μl. The specificity was 100%. The test was easily to perform and the result was stable for at least 1 hour. Conclusion The Clearview® Malaria pLDH was efficient for the diagnosis of malaria. The test was very sensitive for P. falciparum and P. vivax detection. The sensitivities for P. ovale and P. malariae were better than other RDTs PMID:21951996

Molecular identification of the chitinase genes in Plasmodium relictum.

PubMed

Garcia-Longoria, Luz; Hellgren, Olof; Bensch, Staffan

2014-06-18

Malaria parasites need to synthesize chitinase in order to go through the peritrophic membrane, which is created around the mosquito midgut, to complete its life cycle. In mammalian malaria species, the chitinase gene comprises either a large or a short copy. In the avian malaria parasites Plasmodium gallinaceum both copies are present, suggesting that a gene duplication in the ancestor to these extant species preceded the loss of either the long or the short copy in Plasmodium parasites of mammals. Plasmodium gallinaceum is not the most widespread and harmful parasite of birds. This study is the first to search for and identify the chitinase gene in one of the most prevalent avian malaria parasites, Plasmodium relictum. Both copies of P. gallinaceum chitinase were used as reference sequences for primer design. Different sequences of Plasmodium spp. were used to build the phylogenetic tree of chitinase gene. The gene encoding for chitinase was identified in isolates of two mitochondrial lineages of P. relictum (SGS1 and GRW4). The chitinase found in these two lineages consists both of the long (PrCHT1) and the short (PrCHT2) copy. The genetic differences found in the long copy of the chitinase gene between SGS1 and GRW4 were higher than the difference observed for the cytochrome b gene. The identification of both copies in P. relictum sheds light on the phylogenetic relationship of the chitinase gene in the genus Plasmodium. Due to its high variability, the chitinase gene could be used to study the genetic population structure in isolates from different host species and geographic regions.

The Armadillo Repeat Protein PF16 Is Essential for Flagellar Structure and Function in Plasmodium Male Gametes

PubMed Central

Ferguson, David J. P.; Bunting, Karen A.; Xu, Zhengyao; Bailes, Elizabeth; Sinden, Robert E.; Holder, Anthony A.; Smith, Elizabeth F.; Coates, Juliet C.; Rita Tewari

2010-01-01

Malaria, caused by the apicomplexan parasite Plasmodium, threatens 40% of the world's population. Transmission between vertebrate and insect hosts depends on the sexual stages of the life-cycle. The male gamete of Plasmodium parasite is the only developmental stage that possesses a flagellum. Very little is known about the identity or function of proteins in the parasite's flagellar biology. Here, we characterise a Plasmodium PF16 homologue using reverse genetics in the mouse malaria parasite Plasmodium berghei. PF16 is a conserved Armadillo-repeat protein that regulates flagellar structure and motility in organisms as diverse as green algae and mice. We show that P. berghei PF16 is expressed in the male gamete flagellum, where it plays a crucial role maintaining the correct microtubule structure in the central apparatus of the axoneme as studied by electron microscopy. Disruption of the PF16 gene results in abnormal flagellar movement and reduced fertility, but does not lead to complete sterility, unlike pf16 mutations in other organisms. Using homology modelling, bioinformatics analysis and complementation studies in Chlamydomonas, we show that some regions of the PF16 protein are highly conserved across all eukaryotes, whereas other regions may have species-specific functions. PF16 is the first ARM-repeat protein characterised in the malaria parasite genus Plasmodium and this study opens up a novel model for analysis of Plasmodium flagellar biology that may provide unique insights into an ancient organelle and suggest novel intervention strategies to control the malaria parasite. PMID:20886115

Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas.

PubMed

Liu, Weimin; Sundararaman, Sesh A; Loy, Dorothy E; Learn, Gerald H; Li, Yingying; Plenderleith, Lindsey J; Ndjango, Jean-Bosco N; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C; Hahn, Beatrice H; Sharp, Paul M

2016-07-02

Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Characterization of blood dendritic and regulatory T cells in asymptomatic adults with sub-microscopic Plasmodium falciparum or Plasmodium vivax infection.

PubMed

Kho, Steven; Marfurt, Jutta; Handayuni, Irene; Pava, Zuleima; Noviyanti, Rintis; Kusuma, Andreas; Piera, Kim A; Burdam, Faustina H; Kenangalem, Enny; Lampah, Daniel A; Engwerda, Christian R; Poespoprodjo, Jeanne R; Price, Ric N; Anstey, Nicholas M; Minigo, Gabriela; Woodberry, Tonia

2016-06-21

Plasmodium falciparum and Plasmodium vivax infections compromise dendritic cell (DC) function and expand regulatory T (Treg) cells in both clinical disease (malaria) and experimental human sub-microscopic infection. Conversely, in asymptomatic microscopy-positive (patent) P. falciparum or P. vivax infection in endemic areas, blood DC increase or retain HLA-DR expression and Treg cells exhibit reduced activation, suggesting that DC and Treg cells contribute to the control of patent asymptomatic infection. The effect of sub-microscopic (sub-patent) asymptomatic Plasmodium infection on DC and Treg cells in malaria-endemic area residents remains unclear. In a cross-sectional household survey conducted in Papua, Indonesia, 162 asymptomatic adults were prospectively evaluated for DC and Treg cells using field-based flow cytometry. Of these, 161 individuals (99 %) were assessed retrospectively by polymerase chain reaction (PCR), 19 of whom had sub-microscopic infection with P. falciparum and 15 with sub-microscopic P. vivax infection. Flow cytometric data were re-analysed after re-grouping asymptomatic individuals according to PCR results into negative controls, sub-microscopic and microscopic parasitaemia to examine DC and Treg cell phenotype in sub-microscopic infection. Asymptomatic adults with sub-microscopic P. falciparum or P. vivax infection had DC HLA-DR expression and Treg cell activation comparable to PCR-negative controls. Sub-microscopic P. falciparum infection was associated with lower peripheral CD4(+) T cells and lymphocytes, however sub-microscopic Plasmodium infection had no apparent effect on DC sub-set number or Treg cell frequency. In contrast to the impairment of DC maturation/function and the activation of Treg cells seen with sub-microscopic parasitaemia in primary experimental human Plasmodium infection, no phenotypic evidence of dysregulation of DC and Treg cells was observed in asymptomatic sub-microscopic Plasmodium infection in Indonesian adults. This is consistent with DC and Treg cells retaining their functional capacity in sub-microscopic asymptomatic infection with P. falciparum or P. vivax in malaria-endemic areas.

Phylogenetic analysis of simian Plasmodium spp. infecting Anopheles balabacensis Baisas in Sabah, Malaysia

PubMed Central

Manin, Benny O.; Daim, Sylvia; Vythilingam, Indra; Drakeley, Chris

2017-01-01

Background Anopheles balabacensis of the Leucospyrus group has been confirmed as the primary knowlesi malaria vector in Sabah, Malaysian Borneo for some time now. Presently, knowlesi malaria is the only zoonotic simian malaria in Malaysia with a high prevalence recorded in the states of Sabah and Sarawak. Methodology/Principal findings Anopheles spp. were sampled using human landing catch (HLC) method at Paradason village in Kudat district of Sabah. The collected Anopheles were identified morphologically and then subjected to total DNA extraction and polymerase chain reaction (PCR) to detect Plasmodium parasites in the mosquitoes. Identification of Plasmodium spp. was confirmed by sequencing the SSU rRNA gene with species specific primers. MEGA4 software was then used to analyse the SSU rRNA sequences and bulid the phylogenetic tree for inferring the relationship between simian malaria parasites in Sabah. PCR results showed that only 1.61% (23/1,425) of the screened An. balabacensis were infected with one or two of the five simian Plasmodium spp. found in Sabah, viz. Plasmodium coatneyi, P. inui, P. fieldi, P. cynomolgi and P. knowlesi. Sequence analysis of SSU rRNA of Plasmodium isolates showed high percentage of identity within the same Plasmodium sp. group. The phylogenetic tree based on the consensus sequences of P. knowlesi showed 99.7%–100.0% nucleotide identity among the isolates from An. balabacensis, human patients and a long-tailed macaque from the same locality. Conclusions/Significance This is the first study showing high molecular identity between the P. knowlesi isolates from An. balabacensis, human patients and a long-tailed macaque in Sabah. The other common simian Plasmodium spp. found in long-tailed macaques and also detected in An. balabacensis were P. coatneyi, P. inui, P. fieldi and P. cynomolgi. The high percentage identity of nucleotide sequences between the P. knowlesi isolates from the long-tailed macaque, An. balabacensis and human patients suggests a close genetic relationship between the parasites from these hosts. PMID:28968395

The persistence and oscillations of submicroscopic Plasmodium falciparum and Plasmodium vivax infections over time in Vietnam: an open cohort study.

PubMed

Nguyen, Thuy-Nhien; von Seidlein, Lorenz; Nguyen, Tuong-Vy; Truong, Phuc-Nhi; Hung, Son Do; Pham, Huong-Thu; Nguyen, Tam-Uyen; Le, Thanh Dong; Dao, Van Hue; Mukaka, Mavuto; Day, Nicholas Pj; White, Nicholas J; Dondorp, Arjen M; Thwaites, Guy E; Hien, Tran Tinh

2018-05-01

A substantial proportion of Plasmodium species infections are asymptomatic with densities too low to be detectable with standard diagnostic techniques. The importance of such asymptomatic plasmodium infections in malaria transmission is probably related to their duration and density. To explore the duration of asymptomatic plasmodium infections and changes in parasite densities over time, a cohort of participants who were infected with Plasmodium parasites was observed over a 2-year follow-up period. In this open cohort study, inhabitants of four villages in Vietnam were invited to participate in baseline and subsequent 3-monthly surveys up to 24 months, which included the collection of venous blood samples. Samples were batch-screened using ultra-sensitive (u)PCR (lower limit of detection of 22 parasites per mL). Participants found to be infected by uPCR during any of these surveys were invited to join a prospective cohort and provide monthly blood samples. We estimated the persistence of Plasmodium falciparum and Plasmodium vivax infections and changes in parasite densities over a study period of 24 months. Between Dec 1, 2013, and Jan 8, 2016, 356 villagers participated in between one and 22 surveys. These study participants underwent 4248 uPCR evaluations (11·9 tests per participant). 1874 (32%) of 4248 uPCR tests indicated a plasmodium infection; 679 (36%) of 1874 tests were P falciparum monoinfections, 507 (27%) were P vivax monoinfections, 463 (25%) were co-infections with P falciparum and P vivax, and 225 (12%) were indeterminate species of Plasmodium. The median duration of P falciparum infection was 2 months (IQR 1-3); after accounting for censoring, participants had a 20% chance of having parasitaemia for 4 months or longer. The median duration of P vivax infection was 6 months (3-9), and participants had a 59% chance of having parasitaemia for 4 months or longer. The parasite densities of persistent infections oscillated; following ultralow-density infections, high-density infections developed frequently. Persistent largely asymptomatic P vivax and P falciparum infections are common in this area of low seasonal malaria transmission. Infections with low-density parasitaemias can develop into much higher density infections at a later time, which are likely to sustain malaria endemicity. The Wellcome Trust, Bill & Melinda Gates Foundation. Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

DTIC Science & Technology

2010-06-17

Pennsylvania State University College of Medicine, Hershey , Pennsylvania, United States of America Abstract Plasmodium falciparum is a highly lethal malaria...www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000968 Zimmerli S, Edwards S, Ernst JD ( 1996 ) Selective receptor blockade...in field isolates. J Immunol 165: 6341–6346. 22. Baruch DI, Gormely JA, Ma C, Howard RJ, Pasloske BL ( 1996 ) Plasmodium falciparum erythrocyte

Do the mitochondria of malaria parasites behave like the phoenix after return in the mosquito? Regeneration of degenerated mitochondria is required for successful Plasmodium infection.

PubMed

Bongaerts, Ger

2005-01-01

Mitochondria are energy generators in eukaryotic organisms like man and the pathogenic malaria parasites, the Plasmodium spp. From the moment a mosquito-mediated malaria infection occurs in man the parasite multiplies profusely, but eventually the oxygen supply becomes the limiting factor in this process. Consequently, the parasite will increasingly generate energy (and lactic acid) from sugar fermentation. Simultaneously, the cristate structure of Plasmodium mitochondria degenerates and becomes acristate. The degenerated acristate mitochondria of mammalian Plasmodium parasites seem to be able to revitalise by transforming to cristate mitochondria inside the oxygen-rich mosquito, like the rebirth of the old phoenix. In this way the infectivity of the parasite is revitalised.

Genetic approaches to interfere with malaria transmission by vector mosquitoes

PubMed Central

Wang, Sibao; Jacobs-Lorena, Marcelo

2013-01-01

Malaria remains one of the world’s most devastating diseases, causing over one million deaths every year. The most vulnerable stages of Plasmodium development in the vector mosquito occur in the midgut lumen, making the midgut a prime target for intervention. Mosquito transgenesis and paratransgenesis are two novel strategies that aim at rendering the vector incapable of sustaining Plasmodium development. Mosquito transgenesis involves direct genetic engineering of the mosquito itself for delivery of anti-Plasmodium effector molecules. Conversely, paratransgenesis involves the genetic modification of mosquito symbionts for expression of anti-pathogen effector molecules. Here we consider both genetic manipulation strategies for rendering mosquitoes refractory to Plasmodium infection, and discuss challenges for the translation of laboratory findings to field applications. PMID:23395485

Natural Plasmodium infection in monkeys in the state of Rondônia (Brazilian Western Amazon)

PubMed Central

2013-01-01

Background Simian malaria is still an open question concerning the species of Plasmodium parasites and species of New World monkeys susceptible to the parasites. In addition, the lingering question as to whether these animals are reservoirs for human malaria might become important especially in a scenario of eradication of the disease. To aid in the answers to these questions, monkeys were surveyed for malaria parasite natural infection in the Amazonian state of Rondônia, Brazil, a state with intense environmental alterations due to human activities, which facilitated sampling of the animals. Methods Parasites were detected and identified in DNA from blood of monkeys, by PCR with primers for the 18S rRNA, CSP and MSP1 genes and sequencing of the amplified fragments. Multiplex PCR primers for the 18S rRNA genes were designed for the parasite species Plasmodium falciparum and Plasmodium vivax, Plasmodium malariae/Plasmodium brasilianum and Plasmodium simium. Results An overall infection rate of 10.9% was observed or 20 out 184 monkey specimens surveyed, mostly by P. brasilianum. However, four specimens of monkeys were found infected with P. falciparum, two of them doubly infected with P. brasilianum and P. falciparum. In addition, a species of monkey of the family Aotidae, Aotus nigriceps, is firstly reported here naturally infected with P. brasilianum. None of the monkeys surveyed was found infected with P. simium/P. vivax. Conclusion The rate of natural Plasmodium infection in monkeys in the Brazilian state of Rondônia is in line with previous surveys of simian malaria in the Amazon region. The fact that a monkey species was found that had not previously been described to harbour malaria parasites indicates that the list of monkey species susceptible to Plasmodium infection is yet to be completed. Furthermore, finding monkeys in the region infected with P. falciparum clearly indicates parasite transfer from humans to the animals. Whether this parasite can be transferred back to humans and how persistent the parasite is in monkeys in the wild so to be efficient reservoirs of the disease, is yet to be evaluated. Finding different species of monkeys infected with this parasite species suggests indeed that these animals can act as reservoirs of human malaria. PMID:23731624

Evaluation of the rapid diagnostic test CareStart pLDH Malaria (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a reference setting.

PubMed

Heutmekers, Marloes; Gillet, Philippe; Maltha, Jessica; Scheirlinck, Annelies; Cnops, Lieselotte; Bottieau, Emmanuel; Van Esbroeck, Marjan; Jacobs, Jan

2012-06-18

The present study evaluated CareStart pLDH Malaria, a three-band rapid diagnostic test detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH) in a reference setting. CareStart pLDH was retrospectively and prospectively assessed with a panel of stored (n=498) and fresh (n=77) blood samples obtained in international travelers suspected of malaria. Both panels comprised all four Plasmodium species; the retrospective panel comprised also Plasmodium negative samples. The reference method was microscopy corrected by PCR. The prospective panel was run side-to-side with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). In the retrospective evaluation, overall sensitivity for P. falciparum samples (n=247) was 94.7%, reaching 98.7% for parasite densities>1,000/μl. Most false negative results occurred among samples with pure gametocytaemia (2/12, 16.7%) and at parasite densities ≤ 100/μl (7/12, 58.3%). None of the Plasmodium negative samples (n=96) showed visible test lines. Sensitivities for Plasmodium vivax (n=70), Plasmodium ovale (n=69) and Plasmodium malariae (n=16) were 74.3%, 31.9% and 25.0% respectively. Wrong species identification occurred in 10 (2.5%) samples and was mainly due to P. vivax samples reacting with the Pf-pLDH test line. Overall, Pf-pLDH test lines showed higher line intensities compared to the pan-pLDH lines (67.9% and 23.0% medium and strong line intensities for P. falciparum). In the prospective panel (77 Plasmodium-positive samples), CareStart pLDH showed higher sensitivities for P. falciparum compared to OptiMAL (p=0.008), lower sensitivities for P. falciparum as compare to SDFK60 (although not reaching statistical significance, p=0.08) and higher sensitivities for P. ovale compared to both OptiMAL (p=0.03) and SDFK60 (p=0.01). Inter-observer and test reproducibility were good to excellent. CareStart pLDH performed excellent for the detection of P. falciparum, well for P. vivax, but poor for P. ovale and P. malariae.

Explaining variance of avian malaria infection in the wild: the importance of host density, habitat, individual life-history and oxidative stress.

PubMed

Isaksson, Caroline; Sepil, Irem; Baramidze, Vladimer; Sheldon, Ben C

2013-04-08

Avian malaria (Plasmodium sp.) is globally widespread, but considerable variation exists in infection (presence/absence) patterns at small spatial scales. This variation can be driven by variation in ecology, demography, and phenotypic characters, in particular those that influence the host's resistance. Generation of reactive oxygen species (ROS) is one of the host's initial immune responses to combat parasitic invasion. However, long-term ROS exposure can harm the host and the redox response therefore needs to be adjusted according to infection stage and host phenotype. Here we use experimental and correlational approaches to assess the relative importance of host density, habitat composition, individual level variation and redox physiology for Plasmodium infection in a wild population of great tits, Parus major. We found that 36% of the great tit population was infected with Plasmodium (22% P. relictum and 15% P. circumflexum prevalence) and that patterns of infection were Plasmodium species-specific. First, the infection of P. circumflexum was significantly higher in areas with experimental increased host density, whereas variation in P. relictum infection was mainly attributed to age, sex and reproduction. Second, great tit antioxidant responses - total and oxidizied glutathione - showed age- , sex- and Plasmodium species-specific patterns between infected and uninfected individuals, but reactive oxygen metabolites (ROM) showed only a weak explanatory power for patterns of P. relictum infection. Instead ROM significantly increased with Plasmodium parasitaemia. These results identify some key factors that influence Plasmodium infection in wild birds, and provide a potential explanation for the underlying physiological basis of recently documented negative effects of chronic avian malaria on survival and reproductive success.

A retrospective survey into the presence of Plasmodium spp. and Toxoplasma gondii in archived tissue samples from New Zealand raptors: New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaeseelandiae).

PubMed

Mirza, V; Burrows, E B; Gils, S; Hunter, S; Gartrell, B D; Howe, L

2017-08-01

Human colonisation of New Zealand has resulted in the introduction of emerging diseases, such as avian malaria and toxoplasmosis, which arrived with their exotic avian and mammalian hosts. Plasmodium spp. and Toxoplasma gondii have a wide host range, and several species of endemic New Zealand birds have developed a fatal disease following infection with either pathogen. However, no reports of either toxoplasmosis or avian malaria in New Zealand raptors, namely, the New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaeseelandiae) exist in the literature. Therefore, this study was designed to determine if these two pathogens are present in these raptors through a retrospective analysis of archived tissue samples. Detection and isolate identification of these pathogens was determined using established histological and molecular techniques. All three species of New Zealand raptors tested positive for the presence of Plasmodium spp. (10/117; 8.5%) and an atypical genotype of T. gondii (9/117; 7.7%). Plasmodium lineages identified include P. elongatum GRW6, P. relictum SGS1, P. relictum PADOM02 and Plasmodium sp. LINN1. Two Australasian harriers and one morepork tested positive for the presence of both Plasmodium spp. and T. gondii. However, the pathogenicity of these organisms to the raptors is unclear as none of the tissues showed histological evidence of clinical disease associated with Plasmodium spp. and T. gondii infections. Thus, these results demonstrate for the first time that these two potential pathogens are present in New Zealand's raptors; however, further research is required to determine the prevalence and pathogenicity of these organisms among the living populations of these birds in the country.

Plasmodium malariae in the Colombian Amazon region: you don't diagnose what you don't suspect.

PubMed

Niño, Carlos Hernando; Cubides, Juan Ricardo; Camargo-Ayala, Paola Andrea; Rodríguez-Celis, Carlos Arturo; Quiñones, Teódulo; Cortés-Castillo, Moisés Tomás; Sánchez-Suárez, Lizeth; Sánchez, Ricardo; Patarroyo, Manuel Elkin; Patarroyo, Manuel Alfonso

2016-11-29

Malaria is a worldwide public health problem; parasites from the genus Plasmodium spp. are the aetiological agent of this disease. The parasite is mainly diagnosed by microscope-based techniques. However, these have limited sensitivity. Many asymptomatic infections are sub-microscopic and can only be detected by molecular methods. This study was aimed at comparing nested PCR results to those obtained by microscope for diagnosing malaria and to present epidemiological data regarding malaria in Colombia's Amazon department. A total of 1392 blood samples (taken by venepuncture) from symptomatic patients in Colombia's Amazon department were analysed in parallel by thick blood smear (TBS) test and nested PCR for determining Plasmodium spp. infection and identifying infecting species, such as Plasmodium vivax, Plasmodium malariae and/or Plasmodium falciparum. Descriptive statistics were used for comparing the results from both tests regarding detection of the disease, typing infecting species and their prevalence in the study region. Bearing the microscope assay in mind as gold standard, PCR diagnosis performance was evaluated by statistical indicators. The present study revealed great differences between both diagnostic tests, as well as suggesting high P. malariae prevalence from a molecular perspective. This differed profoundly from previous studies in this region of Colombia, usually based on the TBS test, suggesting that diagnosis by conventional techniques could lead to underestimating the prevalence of certain Plasmodium spp. having high circulation in this area. The present results highlight the need for modifying state malaria surveillance schemes for more efficient strategies regarding the detection of this disease in endemic areas. The importance of PCR as a back-up test in cases of low parasitaemia or mixed infection is also highlighted.

Submicroscopic placental infection by non-falciparum Plasmodium spp.

PubMed

Doritchamou, Justin Y A; Akuffo, Richard A; Moussiliou, Azizath; Luty, Adrian J F; Massougbodji, Achille; Deloron, Philippe; Tuikue Ndam, Nicaise G

2018-02-01

Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy. Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed. Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes.

Malaria rapid diagnostic tests in endemic settings.

PubMed

Maltha, J; Gillet, P; Jacobs, J

2013-05-01

Malaria rapid diagnostic tests (RDTs) are instrument-free tests that provide results within 20 min and can be used by community health workers. RDTs detect antigens produced by the Plasmodium parasite such as Plasmodium falciparum histidine-rich protein-2 (PfHPR2) and Plasmodium lactate dehydrogenase (pLDH). The accuracy of RDTs for the diagnosis of uncomplicated P. falciparum infection is equal or superior to routine microscopy (but inferior to expert microscopy). Sensitivity for Plasmodium vivax is 75-100%; for Plasmodium ovale and Plasmodium malariae, diagnostic performance is poor. Design limitations of RDTs include poor sensitivity at low parasite densities, susceptibility to the prozone effect (PfHRP2-detecting RDTs), false-negative results due to PfHRP2 deficiency in the case of pfhrp2 gene deletions (PfHRP2-detecting RDTs), cross-reactions between Plasmodium antigens and detection antibodies, false-positive results by other infections and susceptibility to heat and humidity. End-user's errors relate to safety, procedure (delayed reading, incorrect sample and buffer volumes) and interpretation (not recognizing invalid test results, disregarding faint test lines). Withholding antimalarial treatment in the case of negative RDT results tends to be infrequent and tendencies towards over-prescription of antibiotics have been noted. Numerous shortcomings in RDT kits' labelling, instructions for use (correctness and readability) and contents have been observed. The World Health Organization and partners actively address quality assurance of RDTs by comparative testing of RDTs, inspections of manufacturing sites, lot testing and training tools but no formal external quality assessment programme of end-user performance exists. Elimination of malaria requires RDTs with lower detection limits, for which nucleic acid amplification tests are under development. © 2013 The Authors Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.

Exposure, infection, systemic cytokine levels and antibody responses in young children concurrently exposed to schistosomiasis and malaria

PubMed Central

IMAI, NATSUKO; RUJENI, NADINE; NAUSCH, NORMAN; BOURKE, CLAIRE D.; APPLEBY, LAURA J.; COWAN, GRAEME; GWISAI, REGGIS; MIDZI, NICHOLAS; CAVANAGH, DAVID; MDULUZA, TAKAFIRA; TAYLOR, DAVID; MUTAPI, FRANCISCA

2011-01-01

SUMMARY Despite the overlapping distribution of Schistosoma haematobium and Plasmodium falciparum infections, few studies have investigated early immune responses to both parasites in young children resident in areas co-endemic for the parasites. This study measures infection levels of both parasites and relates them to exposure and immune responses in young children. Levels of IgM, IgE, IgG4 directed against schistosome cercariae, egg and adult worm and IgM, IgG directed against P. falciparum schizonts and the merozoite surface proteins 1 and 2 together with the cytokines IFN-γ, IL-4, IL-5, IL-10 and TNF-α were measured by ELISA in 95 Zimbabwean children aged 1–5 years. Schistosome infection prevalence was 14·7% and that of Plasmodium infection was 0% in the children. 43. 4% of the children showed immunological evidence of exposure to schistosome parasites and 13% showed immunological evidence of exposure to Plasmodium parasites. Schistosome–specific responses, indicative of exposure to parasite antigens, were positively associated with cercariae-specific IgE responses, while Plasmodium-specific responses, indicative of exposure to parasite antigens, were negatively associated with responses associated with protective immunity against Plasmodium. There was no significant association between schistosome-specific and Plasmodium-specific responses. Systemic cytokine levels rose with age as well as with schistosome infection and exposure. Overall the results show that (1) significantly more children are exposed to schistosome and Plasmodium infection than those currently infected and; (2) the development of protective acquired immunity commences in early childhood, although its effects on infection levels and pathology may take many years to become apparent. PMID:21813042

Plasmodium falciparum cerebral malaria complicated by disseminated intravascular coagulation and symmetrical peripheral gangrene: case report and review.

PubMed

Liechti, M E; Zumsteg, V; Hatz, C F R; Herren, T

2003-09-01

The case of a 56-year-old female tourist who survived cerebral Plasmodium falciparum malaria with disseminated intravascular coagulation and symmetrical peripheral gangrene, ultimately requiring amputation of her left-sided fingertips and toes, is reported. While symmetrical peripheral gangrene has been described rarely in Asian, African, and American patients with Plasmodium falciparum malaria and disseminated intravascular coagulation, no such case has been reported in travelers returning from endemic areas.

Contribution of Plasmodium knowlesi to Multispecies Human Malaria Infections in North Sumatera, Indonesia.

PubMed

Lubis, Inke N D; Wijaya, Hendri; Lubis, Munar; Lubis, Chairuddin P; Divis, Paul C S; Beshir, Khalid B; Sutherland, Colin J

2017-04-01

As Indonesia works toward the goal of malaria elimination, information is lacking on malaria epidemiology from some western provinces. As a basis for studies of antimalarial efficacy, we set out to survey parasite carriage in 3 communities in North Sumatera Province. A combination of active and passive detection of infection was carried out among communities in Batubara, Langkat, and South Nias regencies. Finger-prick blood samples from consenting individuals of all ages provided blood films for microscopic examination and blood spots on filter paper. Plasmodium species were identified using nested polymerase chain reaction (PCR) of ribosomal RNA genes and a novel assay that amplifies a conserved sequence specific for the sicavar gene family of Plasmodium knowlesi. Of 3731 participants, 614 (16.5%) were positive for malaria parasites by microscopy. PCR detected parasite DNA in samples from 1169 individuals (31.3%). In total, 377 participants (11.8%) harbored P. knowlesi. Also present were Plasmodium vivax (14.3%), Plasmodium falciparum (10.5%) and Plasmodium malariae (3.4%). Amplification of sicavar is a specific and sensitive test for the presence of P. knowlesi DNA in humans. Subpatent and asymptomatic multispecies parasitemia is relatively common in North Sumatera, so PCR-based surveillance is required to support control and elimination activities. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Coquillettidia (Culicidae, Diptera) mosquitoes are natural vectors of avian malaria in Africa

PubMed Central

2009-01-01

Background The mosquito vectors of Plasmodium spp. have largely been overlooked in studies of ecology and evolution of avian malaria and other vertebrates in wildlife. Methods Plasmodium DNA from wild-caught Coquillettidia spp. collected from lowland forests in Cameroon was isolated and sequenced using nested PCR. Female Coquillettidia aurites were also dissected and salivary glands were isolated and microscopically examined for the presence of sporozoites. Results In total, 33% (85/256) of mosquito pools tested positive for avian Plasmodium spp., harbouring at least eight distinct parasite lineages. Sporozoites of Plasmodium spp. were recorded in salivary glands of C. aurites supporting the PCR data that the parasites complete development in these mosquitoes. Results suggest C. aurites, Coquillettidia pseudoconopas and Coquillettidia metallica as new and important vectors of avian malaria in Africa. All parasite lineages recovered clustered with parasites formerly identified from several bird species and suggest the vectors capability of infecting birds from different families. Conclusion Identifying the major vectors of avian Plasmodium spp. will assist in understanding the epizootiology of avian malaria, including differences in this disease distribution between pristine and disturbed landscapes. PMID:19664282

Fighting malaria with engineered symbiotic bacteria from vector mosquitoes.

PubMed

Wang, Sibao; Ghosh, Anil K; Bongio, Nicholas; Stebbings, Kevin A; Lampe, David J; Jacobs-Lorena, Marcelo

2012-07-31

The most vulnerable stages of Plasmodium development occur in the lumen of the mosquito midgut, a compartment shared with symbiotic bacteria. Here, we describe a strategy that uses symbiotic bacteria to deliver antimalaria effector molecules to the midgut lumen, thus rendering host mosquitoes refractory to malaria infection. The Escherichia coli hemolysin A secretion system was used to promote the secretion of a variety of anti-Plasmodium effector proteins by Pantoea agglomerans, a common mosquito symbiotic bacterium. These engineered P. agglomerans strains inhibited development of the human malaria parasite Plasmodium falciparum and rodent malaria parasite Plasmodium berghei by up to 98%. Significantly, the proportion of mosquitoes carrying parasites (prevalence) decreased by up to 84% for two of the effector molecules, scorpine, a potent antiplasmodial peptide and (EPIP)(4), four copies of Plasmodium enolase-plasminogen interaction peptide that prevents plasminogen binding to the ookinete surface. We demonstrate the use of an engineered symbiotic bacterium to interfere with the development of P. falciparum in the mosquito. These findings provide the foundation for the use of genetically modified symbiotic bacteria as a powerful tool to combat malaria.

Molecular make-up of the Plasmodium parasitophorous vacuolar membrane.

PubMed

Spielmann, Tobias; Montagna, Georgina N; Hecht, Leonie; Matuschewski, Kai

2012-10-01

Plasmodium, the causative agent of malaria, is an obligate, intracellular, eukaryotic cell that invades, replicates, and differentiates within hepatocytes and erythrocytes. Inside a host cell, a second membrane delineates the developing pathogen in addition to the parasite plasma membrane, resulting in a distinct cellular compartment, termed parasitophorous vacuole (PV). The PV membrane (PVM) constitutes the parasite-host cell interface and is likely central to nutrient acquisition, host cell remodeling, waste disposal, environmental sensing, and protection from innate defense. Over the past two decades, a number of parasite-encoded PVM proteins have been identified. They include multigene families and protein complexes, such as early-transcribed membrane proteins (ETRAMPs) and the Plasmodium translocon for exported proteins (PTEX). Nearly all Plasmodium PVM proteins are restricted to this genus and display transient and stage-specific expression. Here, we provide an overview of the PVM proteins of Plasmodium blood and liver stages. Biochemical and experimental genetics data suggest that some PVM proteins are ideal targets for novel anti-malarial intervention strategies. Copyright © 2012 Elsevier GmbH. All rights reserved.

Structural Determinants of the 5′-Methylthioinosine Specificity of Plasmodium Purine Nucleoside Phosphorylase

PubMed Central

Donaldson, Teraya M.; Ting, Li-Min; Zhan, Chenyang; Shi, Wuxian; Zheng, Renjian; Almo, Steven C.; Kim, Kami

2014-01-01

Plasmodium parasites rely upon purine salvage for survival. Plasmodium purine nucleoside phosphorylase is part of the streamlined Plasmodium purine salvage pathway that leads to the phosphorylysis of both purines and 5′-methylthiopurines, byproducts of polyamine synthesis. We have explored structural features in Plasmodium falciparum purine nucleoside phosphorylase (PfPNP) that affect efficiency of catalysis as well as those that make it suitable for dual specificity. We used site directed mutagenesis to identify residues critical for PfPNP catalytic activity as well as critical residues within a hydrophobic pocket required for accommodation of the 5′-methylthio group. Kinetic analysis data shows that several mutants had disrupted binding of the 5′-methylthio group while retaining activity for inosine. A triple PfPNP mutant that mimics Toxoplasma gondii PNP had significant loss of 5′-methylthio activity with retention of inosine activity. Crystallographic investigation of the triple mutant PfPNP with Tyr160Phe, Val66Ile, andVal73Ile in complex with the transition state inhibitor immucillin H reveals fewer hydrogen bond interactions for the inhibitor in the hydrophobic pocket. PMID:24416224

Persistent Parasitism: The Adaptive Biology of Malariae and Ovale Malaria.

PubMed

Sutherland, Colin J

2016-10-01

Plasmodium malariae causes malaria in humans throughout the tropics and subtropics. Plasmodium ovale curtisi and Plasmodium ovale wallikeri are sympatric sibling species common in sub-Saharan Africa and also found in Oceania and Asia. Although rarely identified as the cause of malaria cases in endemic countries, PCR detection has confirmed all three parasite species to be more prevalent, and persistent, than previously thought. Chronic, low-density, multispecies asymptomatic infection is a successful biological adaptation by these Plasmodium spp., a pattern also observed among malaria parasites of wild primates. Current whole-genome analyses are illuminating the species barrier separating the ovale parasite species and reveal substantial expansion of subtelomeric gene families. The evidence for and against a quiescent pre-erythrocytic form of P. malariae is reviewed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plasmodium knowlesi: from severe zoonosis to animal model.

PubMed

Cox-Singh, Janet; Culleton, Richard

2015-06-01

Plasmodium knowlesi malaria is a newly described zoonosis in Southeast Asia. Similarly to Plasmodium falciparum, P. knowlesi can reach high parasitaemia in the human host and both species cause severe and fatal illness. Interpretation of host-parasite interactions in studies of P. knowlesi malaria adds a counterpoint to studies on P. falciparum. However, there is no model system for testing the resulting hypotheses on malaria pathophysiology or for developing new interventions. Plasmodium knowlesi is amenable to genetic manipulation in vitro and several nonhuman primate species are susceptible to experimental infection. Here, we make a case for drawing on P. knowlesi as both a human pathogen and an experimental model to lift the roadblock between malaria research and its translation into human health benefits. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using Click Chemistry to Identify Potential Drug Targets in Plasmodium

DTIC Science & Technology

2015-04-01

step of the Plasmodium mammalian cycle . Inhibiting this step can block malaria at an early step. However, few anti-malarials target liver infection...points in the life cycle of malaria parasites. PLoS Biol 12: e1001806. 2. Falae A, Combe A, Amaladoss A, Carvalho T, Menard R, et al. (2010) Role of...AWARD NUMBER: W81XWH-13-1-0429 TITLE: Using "Click Chemistry" to Identify Potential Drug Targets in Plasmodium PRINCIPAL INVESTIGATOR: Dr. Purnima

Changing epidemiology of malaria in Sabah, Malaysia: increasing incidence of Plasmodium knowlesi.

PubMed

William, Timothy; Jelip, Jenarun; Menon, Jayaram; Anderios, Fread; Mohammad, Rashidah; Awang Mohammad, Tajul A; Grigg, Matthew J; Yeo, Tsin W; Anstey, Nicholas M; Barber, Bridget E

2014-10-02

While Malaysia has had great success in controlling Plasmodium falciparum and Plasmodium vivax, notifications of Plasmodium malariae and the microscopically near-identical Plasmodium knowlesi increased substantially over the past decade. However, whether this represents microscopic misdiagnosis or increased recognition of P. knowlesi has remained uncertain. To describe the changing epidemiology of malaria in Sabah, in particular the increasing incidence of P. knowlesi, a retrospective descriptive study was undertaken involving a review of Department of Health malaria notification data from 2012-2013, extending a previous review of these data from 1992-2011. In addition, malaria PCR and microscopy data from the State Public Health Laboratory were reviewed to estimate the accuracy of the microscopy-based notification data. Notifications of P. malariae/P. knowlesi increased from 703 in 2011 to 815 in 2012 and 996 in 2013. Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013. In 2013, P. malariae/P. knowlesi accounted for 62% of all malaria notifications compared to 35% in 2011. Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative. Plasmodium knowlesi mono-infection accounted for 32/156 (21%) and 33/87 (38%) blood slides diagnosed by microscopy as P. falciparum and P. vivax, respectively. Twenty-six malaria deaths were reported during 2010-2013, including 12 with 'P. malariae/P. knowlesi' (all adults), 12 with P. falciparum (seven adults), and two adults with P. vivax. Notifications of P. malariae/P. knowlesi in Sabah are increasing, with this trend likely reflecting a true increase in incidence of P. knowlesi and presenting a major threat to malaria control and elimination in Malaysia. With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

Evidence of non-Plasmodium falciparum malaria infection in Kédougou, Sénégal.

PubMed

Daniels, Rachel F; Deme, Awa Bineta; Gomis, Jules F; Dieye, Baba; Durfee, Katelyn; Thwing, Julie I; Fall, Fatou B; Ba, Mady; Ndiop, Medoune; Badiane, Aida S; Ndiaye, Yaye Die; Wirth, Dyann F; Volkman, Sarah K; Ndiaye, Daouda

2017-01-03

Expanded malaria control efforts in Sénégal have resulted in increased use of rapid diagnostic tests (RDT) to identify the primary disease-causing Plasmodium species, Plasmodium falciparum. However, the type of RDT utilized in Sénégal does not detect other malaria-causing species such as Plasmodium ovale spp., Plasmodium malariae, or Plasmodium vivax. Consequently, there is a lack of information about the frequency and types of malaria infections occurring in Sénégal. This study set out to better determine whether species other than P. falciparum were evident among patients evaluated for possible malaria infection in Kédougou, Sénégal. Real-time polymerase chain reaction speciation assays for P. vivax, P. ovale spp., and P. malariae were developed and validated by sequencing and DNA extracted from 475 Plasmodium falciparum-specific HRP2-based RDT collected between 2013 and 2014 from a facility-based sample of symptomatic patients from two health clinics in Kédougou, a hyper-endemic region in southeastern Sénégal, were analysed. Plasmodium malariae (n = 3) and P. ovale wallikeri (n = 2) were observed as co-infections with P. falciparum among patients with positive RDT results (n = 187), including one patient positive for all three species. Among 288 negative RDT samples, samples positive for P. falciparum (n = 24), P. ovale curtisi (n = 3), P. ovale wallikeri (n = 1), and P. malariae (n = 3) were identified, corresponding to a non-falciparum positivity rate of 2.5%. These findings emphasize the limitations of the RDT used for malaria diagnosis and demonstrate that non-P. falciparum malaria infections occur in Sénégal. Current RDT used for routine clinical diagnosis do not necessarily provide an accurate reflection of malaria transmission in Kédougou, Sénégal, and more sensitive and specific methods are required for diagnosis and patient care, as well as surveillance and elimination activities. These findings have implications for other malaria endemic settings where species besides P. falciparum may be transmitted and overlooked by control or elimination activities.

High proportion of knowlesi malaria in recent malaria cases in Malaysia

PubMed Central

2014-01-01

Background Plasmodium knowlesi is a simian parasite that has been recognized as the fifth species causing human malaria. Naturally-acquired P. knowlesi infection is widespread among human populations in Southeast Asia. The aim of this epidemiological study was to determine the incidence and distribution of malaria parasites, with a particular focus on human P. knowlesi infection in Malaysia. Methods A total of 457 microscopically confirmed, malaria-positive blood samples were collected from 22 state and main district hospitals in Malaysia between September 2012 and December 2013. Nested PCR assay targeting the 18S rRNA gene was used to determine the infecting Plasmodium species. Results A total of 453 samples were positive for Plasmodium species by using nested PCR assay. Plasmodium knowlesi was identified in 256 (56.5%) samples, followed by 133 (29.4%) cases of Plasmodium vivax, 49 (10.8%) cases of Plasmodium falciparum, two (0.4%) cases of Plasmodium ovale and one (0.2%) case of Plasmodium malariae. Twelve mixed infections were detected, including P. knowlesi/P. vivax (n = 10), P. knowlesi/P. falciparum (n = 1), and P. falciparum/P. vivax (n = 1). Notably, P. knowlesi (Included mixed infections involving P. knowlesi (P. knowlesi/P. vivax and P. knowlesi /P. falciparum)) showed the highest proportion in Sabah (84/115 cases, prevalence of 73.0%), Sarawak (83/120, 69.2%), Kelantan (42/56, 75.0%), Pahang (24/25, 96.0%), Johor (7/9, 77.8%), and Terengganu (4/5, 80.0%,). In contrast, the rates of P. knowlesi infection in Selangor and Negeri Sembilan were found to be 16.2% (18/111 cases) and 50.0% (5/10 cases), respectively. Sample of P. knowlesi was not obtained from Kuala Lumpur, Melaka, Perak, Pulau Pinang, and Perlis during the study period, while a microscopically-positive sample from Kedah was negative by PCR. Conclusion In addition to Sabah and Sarawak, which have been known for high prevalence of P. knowlesi infection, the findings from this study highlight the widespread distribution of P. knowlesi in many Peninsular Malaysia states. PMID:24886266

Evaluation of the rapid diagnostic test SDFK40 (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a non-endemic setting

PubMed Central

2011-01-01

Background The present study evaluated the SD Bioline Malaria Ag 05FK40 (SDFK40), a three-band RDT detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH), in a reference setting. Methods The SDFK40 was retrospectively and prospectively tested against a panel of stored (n = 341) and fresh (n = 181) whole blood samples obtained in international travelers suspected of malaria, representing the four Plasmodium species as well as Plasmodium negative samples, and compared to microscopy and PCR results. The prospective panel was run together with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). Results Overall sensitivities for P. falciparum tested retrospectively and prospectively were 67.9% and 78.8%, reaching 100% and 94.6% at parasite densities >1,000/μl. Sensitivity at parasite densities ≤ 100/μl was 9.1%. Overall sensitivities for Plasmodium vivax and Plasmodium ovale were 86.7% and 80.0% (retrospectively) and 92.9% and 76.9% (prospectively), reaching 94.7% for both species (retrospective panel) at parasite densities >500/μl. Sensitivity for Plasmodium malariae was 21.4%. Species mismatch occurred in 0.7% of samples (3/411) and was limited to non-falciparum species erroneously identified as P. falciparum. None of the Plasmodium negative samples in the retrospective panel reacted positive. Compared to OptiMAL and SDFK60, SDFK40 showed lower sensitivities for P. falciparum, but better detection of P. ovale. Inter-observer agreement and test reproducibility were excellent, but lot-to-lot variability was observed for pan-pLDH results in case of P. falciparum. Conclusion SDFK40 performance was poor at low (≤ 100/μl) parasite densities, precluding its use as the only diagnostic tool for malaria diagnosis. SDFK40 performed excellent for P. falciparum samples at high (>1,000/μl) parasite densities as well as for detection of P. vivax and P. ovale at parasite densities >500/μl. PMID:21226920

Evaluation of the rapid diagnostic test SDFK40 (Pf-pLDH/pan-pLDH) for the diagnosis of malaria in a non-endemic setting.

PubMed

Maltha, Jessica; Gillet, Philippe; Cnops, Lieselotte; Bottieau, Emmanuel; Van Esbroeck, Marjan; Bruggeman, Cathrien; Jacobs, Jan

2011-01-12

The present study evaluated the SD Bioline Malaria Ag 05FK40 (SDFK40), a three-band RDT detecting Plasmodium falciparum-specific parasite lactate dehydrogenase (Pf-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH), in a reference setting. The SDFK40 was retrospectively and prospectively tested against a panel of stored (n = 341) and fresh (n = 181) whole blood samples obtained in international travelers suspected of malaria, representing the four Plasmodium species as well as Plasmodium negative samples, and compared to microscopy and PCR results. The prospective panel was run together with OptiMAL (Pf-pLDH/pan-pLDH) and SDFK60 (histidine-rich protein-2 (HRP-2)/pan-pLDH). Overall sensitivities for P. falciparum tested retrospectively and prospectively were 67.9% and 78.8%, reaching 100% and 94.6% at parasite densities >1,000/μl. Sensitivity at parasite densities ≤ 100/μl was 9.1%. Overall sensitivities for Plasmodium vivax and Plasmodium ovale were 86.7% and 80.0% (retrospectively) and 92.9% and 76.9% (prospectively), reaching 94.7% for both species (retrospective panel) at parasite densities >500/μl. Sensitivity for Plasmodium malariae was 21.4%. Species mismatch occurred in 0.7% of samples (3/411) and was limited to non-falciparum species erroneously identified as P. falciparum. None of the Plasmodium negative samples in the retrospective panel reacted positive. Compared to OptiMAL and SDFK60, SDFK40 showed lower sensitivities for P. falciparum, but better detection of P. ovale. Inter-observer agreement and test reproducibility were excellent, but lot-to-lot variability was observed for pan-pLDH results in case of P. falciparum. SDFK40 performance was poor at low (≤ 100/μl) parasite densities, precluding its use as the only diagnostic tool for malaria diagnosis. SDFK40 performed excellent for P. falciparum samples at high (>1,000/μl) parasite densities as well as for detection of P. vivax and P. ovale at parasite densities >500/μl.

Erythrocytic adenosine monophosphate as an alternative purine source in Plasmodium falciparum.

PubMed

Cassera, María B; Hazleton, Keith Z; Riegelhaupt, Paul M; Merino, Emilio F; Luo, Minkui; Akabas, Myles H; Schramm, Vern L

2008-11-21

Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum.

Parasite-induced ER stress response in hepatocytes facilitates Plasmodium liver stage infection.

PubMed

Inácio, Patricia; Zuzarte-Luís, Vanessa; Ruivo, Margarida T G; Falkard, Brie; Nagaraj, Nagarjuna; Rooijers, Koos; Mann, Matthias; Mair, Gunnar; Fidock, David A; Mota, Maria M

2015-08-01

Upon infection of a mammalian host, Plasmodium parasites first replicate inside hepatocytes, generating thousands of new parasites. Although Plasmodium intra-hepatic development represents a substantial metabolic challenge to the host hepatocyte, how infected cells respond to and integrate this stress remains poorly understood. Here, we present proteomic and transcriptomic analyses, revealing that the endoplasmic reticulum (ER)-resident unfolded protein response (UPR) is activated in host hepatocytes upon Plasmodium berghei infection. The expression of XBP1s--the active form of the UPR mediator XBP1--and the liver-specific UPR mediator CREBH is induced by P. berghei infection in vivo. Furthermore, this UPR induction increases parasite liver burden. Altogether, our data suggest that ER stress is a central feature of P. berghei intra-hepatic development, contributing to the success of infection. © 2015 The Authors.

Parasite-induced ER stress response in hepatocytes facilitates Plasmodium liver stage infection

PubMed Central

Inácio, Patricia; Zuzarte-Luís, Vanessa; Ruivo, Margarida TG; Falkard, Brie; Nagaraj, Nagarjuna; Rooijers, Koos; Mann, Matthias; Mair, Gunnar; Fidock, David A; Mota, Maria M

2015-01-01

Upon infection of a mammalian host, Plasmodium parasites first replicate inside hepatocytes, generating thousands of new parasites. Although Plasmodium intra-hepatic development represents a substantial metabolic challenge to the host hepatocyte, how infected cells respond to and integrate this stress remains poorly understood. Here, we present proteomic and transcriptomic analyses, revealing that the endoplasmic reticulum (ER)-resident unfolded protein response (UPR) is activated in host hepatocytes upon Plasmodium berghei infection. The expression of XBP1s—the active form of the UPR mediator XBP1—and the liver-specific UPR mediator CREBH is induced by P. berghei infection in vivo. Furthermore, this UPR induction increases parasite liver burden. Altogether, our data suggest that ER stress is a central feature of P. berghei intra-hepatic development, contributing to the success of infection. PMID:26113366

Case Report: A Case of Plasmodium falciparum hrp2 and hrp3 Gene Mutation in Bangladesh.

PubMed

Nima, Maisha Khair; Hougard, Thomas; Hossain, Mohammad Enayet; Kibria, Mohammad Golam; Mohon, Abu Naser; Johora, Fatema Tuj; Rahman, Rajibur; Haque, Rashidul; Alam, Mohammad Shafiul

2017-10-01

Several species of Plasmodium are responsible for causing malaria in humans. Proper diagnoses are crucial to case management, because severity and treatment varies between species. Diagnoses can be made using rapid diagnostic tests (RDTs), which detect Plasmodium proteins. Plasmodium falciparum causes the most virulent cases of malaria, and P. falciparum histidine-rich protein 2 (PfHRP2) is a common target of falciparum malaria RDTs. Here we report a case in which a falciparum malaria patient in Bangladesh tested negative on PfHRP2-based RDTs. The negative results can be attributed to a deletion of part of the pfhrp2 gene and frameshift mutations in both pfhrp2 and pfhrp3 gene. This finding may have implications for malaria diagnostics and case management in Bangladesh and other regions of South Asia.

Plasmodium parasites in reptiles from the Colombia Orinoco-Amazon basin: a re-description of Plasmodium kentropyxi Lainson R, Landau I, Paperna I, 2001 and Plasmodium carmelinoi Lainson R, Franco CM, da Matta R, 2010.

PubMed

Matta, Nubia E; González, Leydy P; Pacheco, M Andreína; Escalante, Ananías A; Moreno, Andrea M; González, Angie D; Calderón-Espinosa, Martha L

2018-05-01

Colombia is a megadiverse country with about 600 species of reptiles; however, there are few studies on species of hemoparasites found in this taxonomic group. Here, we document the presence of Plasmodium spp. in four species of reptiles from the northern part of the Orinoco-Amazon region in Colombia. Individuals analyzed in this study were captured in localities between 200 and 500 m altitude, in the department of Guaviare. Each sample was screened for haemosporidian parasites by using morphology and a nested polymerase chain reaction (PCR) protocol that targets the mitochondrial cytochrome b (cytb) gene. Four morphotypes of the genus Plasmodium were found; two of these species are re-described using morphological and molecular data (cytb). For the other two morphotypes, it was not possible to assign a described species. Among those, Plasmodium screened one species was only detected by microscopy. Considering the potential species diversity, it is possible that commonly used primers may not detect all species, reinforcing the importance of using microscopy in haematozoa surveys. There was no correspondence between the morphological traits associated with the subgenera and the phylogenetic relationships that we found in our analyses. Additionally, we found an expansion in the geographical distribution of these two species, and a new host for P. kentropyxi, demonstrating that studies of tropical herpetofauna and their parasites deserve more attention.

Out of Africa: origins and evolution of the human malaria parasites Plasmodium falciparum and Plasmodium vivax.

PubMed

Loy, Dorothy E; Liu, Weimin; Li, Yingying; Learn, Gerald H; Plenderleith, Lindsey J; Sundararaman, Sesh A; Sharp, Paul M; Hahn, Beatrice H

2017-02-01

Plasmodium falciparum and Plasmodium vivax account for more than 95% of all human malaria infections, and thus pose a serious public health challenge. To control and potentially eliminate these pathogens, it is important to understand their origins and evolutionary history. Until recently, it was widely believed that P. falciparum had co-evolved with humans (and our ancestors) over millions of years, whilst P. vivax was assumed to have emerged in southeastern Asia following the cross-species transmission of a parasite from a macaque. However, the discovery of a multitude of Plasmodium spp. in chimpanzees and gorillas has refuted these theories and instead revealed that both P. falciparum and P. vivax evolved from parasites infecting wild-living African apes. It is now clear that P. falciparum resulted from a recent cross-species transmission of a parasite from a gorilla, whilst P. vivax emerged from an ancestral stock of parasites that infected chimpanzees, gorillas and humans in Africa, until the spread of the protective Duffy-negative mutation eliminated P. vivax from human populations there. Although many questions remain concerning the biology and zoonotic potential of the P. falciparum- and P. vivax-like parasites infecting apes, comparative genomics, coupled with functional parasite and vector studies, are likely to yield new insights into ape Plasmodium transmission and pathogenesis that are relevant to the treatment and prevention of human malaria. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

In silico identification of genetically attenuated vaccine candidate genes for Plasmodium liver stage.

PubMed

Kumar, Hirdesh; Frischknecht, Friedrich; Mair, Gunnar R; Gomes, James

2015-12-01

Genetically attenuated parasites (GAPs) that lack genes essential for the liver stage of the malaria parasite, and therefore cause developmental arrest, have been developed as live vaccines in rodent malaria models and recently been tested in humans. The genes targeted for deletion were often identified by trial and error. Here we present a systematic gene - protein and transcript - expression analyses of several Plasmodium species with the aim to identify candidate genes for the generation of novel GAPs. With a lack of liver stage expression data for human malaria parasites, we used data available for liver stage development of Plasmodium yoelii, a rodent malaria model, to identify proteins expressed in the liver stage but absent from blood stage parasites. An orthology-based search was then employed to identify orthologous proteins in the human malaria parasite Plasmodium falciparum resulting in a total of 310 genes expressed in the liver stage but lacking evidence of protein expression in blood stage parasites. Among these 310 possible GAP candidates, we further studied Plasmodium liver stage proteins by phyletic distribution and functional domain analyses and shortlisted twenty GAP-candidates; these are: fabB/F, fabI, arp, 3 genes encoding subunits of the PDH complex, dnaJ, urm1, rS5, ancp, mcp, arh, gk, lisp2, valS, palm, and four conserved Plasmodium proteins of unknown function. Parasites lacking one or several of these genes might yield new attenuated malaria parasites for experimental vaccination studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Proteomic Identification and Analysis of Arginine-Methylated Proteins of Plasmodium falciparum at Asexual Blood Stages.

PubMed

Zeeshan, Mohammad; Kaur, Inderjeet; Joy, Joseph; Saini, Ekta; Paul, Gourab; Kaushik, Abhinav; Dabral, Surbhi; Mohmmed, Asif; Gupta, Dinesh; Malhotra, Pawan

2017-02-03

Plasmodium falciparum undergoes a tightly regulated developmental process in human erythrocytes, and recent studies suggest an important regulatory role of post-translational modifications (PTMs). As compared with Plasmodium phosphoproteome, little is known about other PTMs in the parasite. In the present study, we performed a global analysis of asexual blood stages of Plasmodium falciparum to identify arginine-methylated proteins. Using two different methyl arginine-specific antibodies, we immunoprecipitated the arginine-methylated proteins from the stage-specific parasite lysates and identified 843 putative arginine-methylated proteins by LC-MS/MS. Motif analysis of the protein sequences unveiled that the methylation sites are associated with the previously known methylation motifs such as GRx/RGx, RxG, GxxR, or WxxxR. We identified Plasmodium homologues of known arginine-methylated proteins in trypanosomes, yeast, and human. Hydrophilic interaction liquid chromatography (HILIC) was performed on the immunoprecipitates from the trophozoite stage to enrich arginine-methylated peptides. Mass spectrometry analysis of immunoprecipitated and HILIC fractions identified 55 arginine-methylated peptides having 62 methylated arginine sites. Functional classification revealed that the arginine-methylated proteins are involved in RNA metabolism, protein synthesis, intracellular protein trafficking, proteolysis, protein folding, chromatin organization, hemoglobin metabolic process, and several other functions. Summarily, the findings suggest that protein methylation of arginine residues is a widespread phenomenon in Plasmodium, and the PTM may play an important regulatory role in a diverse set of biological pathways, including host-pathogen interactions.

Chimpanzee Malaria Parasites Related to Plasmodium ovale in Africa

PubMed Central

Duval, Linda; Nerrienet, Eric; Rousset, Dominique; Sadeuh Mba, Serge Alain; Houze, Sandrine; Fourment, Mathieu; Le Bras, Jacques; Robert, Vincent; Ariey, Frederic

2009-01-01

Since the 1970's, the diversity of Plasmodium parasites in African great apes has been neglected. Surprisingly, P. reichenowi, a chimpanzee parasite, is the only such parasite to have been molecularly characterized. This parasite is closely phylogenetically related to P. falciparum, the principal cause of the greatest malaria burden in humans. Studies of malaria parasites from anthropoid primates may provide relevant phylogenetic information, improving our understanding of the origin and evolutionary history of human malaria species. In this study, we screened 130 DNA samples from chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) from Cameroon for Plasmodium infection, using cytochrome b molecular tools. Two chimpanzees from the subspecies Pan t. troglodytes presented single infections with Plasmodium strains molecularly related to the human malaria parasite P. ovale. These chimpanzee parasites and 13 human strains of P. ovale originated from a various sites in Africa and Asia were characterized using cytochrome b and cytochrome c oxidase 1 mitochondrial partial genes and nuclear ldh partial gene. Consistent with previous findings, two genetically distinct types of P. ovale, classical and variant, were observed in the human population from a variety of geographical locations. One chimpanzee Plasmodium strain was genetically identical, on all three markers tested, to variant P. ovale type. The other chimpanzee Plasmodium strain was different from P. ovale strains isolated from humans. This study provides the first evidence of possibility of natural cross-species exchange of P. ovale between humans and chimpanzees of the subspecies Pan t. troglodytes. PMID:19436742

Evaluation of CareStart™ malaria Pf/Pv combo test for Plasmodium falciparum and Plasmodium vivax malaria diagnosis in Butajira area, south-central Ethiopia.

PubMed

Woyessa, Adugna; Deressa, Wakgari; Ali, Ahmed; Lindtjørn, Bernt

2013-06-27

Malaria is a major public health problem in Ethiopia. Plasmodium falciparum and Plasmodium vivax co-exist and malaria rapid diagnostic test (RDTs) is vital in rendering parasite-confirmed treatment especially in areas where microscopy from 2008 to 2010 is not available. CareStartTM Malaria Pf/Pv combo test was evaluated compared to microscopy in Butajira area, south-central Ethiopia. This RDT detects histidine-rich protein-2 (HRP2) found in P. falciparum, and Plasmodium enzyme lactate dehydrogenase (pLDH) for diagnosis of P. vivax. The standard for the reporting of diagnostic accuracy studies was complied. Among 2,394 participants enrolled, 10.9% (n=87) were Plasmodium infected (household survey) and 24.5% (n=392) health facility-based using microscopy. In the household surveys, the highest positivity was caused by P. vivax (83.9%, n=73), P. falciparum (15.0%, n=13), and the rest due to mixed infections of both (1.1%, n=1). In health facility, P. vivax caused 78.6% (n=308), P. falciparum caused 20.4% (n=80), and the rest caused by mixed infections 1.0% (n=4). RDT missed 9.1% (n=8) in household and 4.3% (n=17) in health facility-based surveys among Plasmodium positive confirmed by microscopy while 3.3% (n=24) in household and 17.2% (n=208) in health facility-based surveys were detected false positive. RDT showed agreement with microscopy in detecting 79 positives in household surveys (n=796) and 375 positives in health centre survey (n=1,598).RDT performance varied in both survey settings, lowest PPV (64.3%) for Plasmodium and P. falciparum (77.2%) in health centres; and Plasmodium (76.7%) and P. falciparum (87.5%) in household surveys. NPV was low in P. vivax in health centres (77.2%) and household (87.5%) surveys. Seasonally varying RDT precision of as low as 14.3% PPV (Dec. 2009), and 38.5% NPV (Nov. 2008) in health centre surveys; and 40-63.6% PPV was observed in household surveys. But the influence of age and parasite density on RDT performance was not ascertained. Establishing quality control of malaria RDT in the health system in areas with low endemic and where P. falciparum and P. vivax co-exist is recommendable. CareStartTM RDT might be employed for epidemiological studies that require interpreting the results cautiously. Future RDT field evaluation against microscopy should be PCR corrected.

Malaria and related outcomes in patients with intestinal helminths: a cross-sectional study.

PubMed

Degarege, Abraham; Legesse, Mengistu; Medhin, Girmay; Animut, Abebe; Erko, Berhanu

2012-11-09

The effects of helminth co-infection on malaria in humans remain uncertain. This study aimed to evaluate the nature of association of intestinal helminths with prevalence and clinical outcomes of Plasmodium infection. A cross-sectional study involving 1,065 malaria suspected febrile patients was conducted at Dore Bafeno Health Center, Southern Ethiopia, from December 2010 to February 2011. Plasmodium and intestinal helminth infections were diagnosed using Giemsa-stained blood films and Kato-Katz technique, respectively. Haemoglobin level was determined using a haemocue machine. Among 1,065 malaria suspected febrile patients, 28.8% were positive for Plasmodium parasites (P. falciparum =13.0%, P. vivax =14.5%, P. falciparum and P. vivax =1.3%). Among 702 patients who provided stool samples, 53.8%, 31.6% and 19.4% were infected with intestinal helminths, Plasmodium alone and with both Plasmodium and intestinal helminths, respectively. The prevalence of infections with Ascaris lumbricoides (A. lumbricoides), Trichuris trichiura (T. trichiura), Schistosoma mansoni (S. mansoni) and hookworm (9.8%) were 35.9%, 15.8%, 11.7% and 9.8%, respectively. Out of the 222 (31.6%) Plasmodium infected cases, 9 (4.1%) had severe malaria. P. falciparum infection was more common in febrile patients infected with A. lumbricoides alone (21.3%), T. trichiura alone (23.1%) and S. mansoni alone (23.1%) compared to those without intestinal helminth infections (9.3%) (p<0.001 for all). Prevalence of non-severe malaria was significantly higher in individuals infected with intestinal helminths than in those who were not infected with intestinal helminths (adjusted OR=1.58, 95% CI=1.13-2.22). The chance of developing non-severe P. falciparum malaria were 2.6, 2.8 and 3.3 times higher in individuals infected with A. lumbricoides alone, T. trichiura alone and S. mansoni alone, respectively, compared to intestinal helminth-free individuals (p<0.05 for all). The odds ratio for being infected with non-severe P. falciparum increased with the number of intestinal helminth species (p<0.001). Mean Plasmodium density among intestinal helminth infected individuals was significantly increased with the number of intestinal helminths species (p=0.027). Individuals who were co-infected with different species of intestinal helminths and Plasmodium showed lower mean haemoglobin concentration than individuals who were infected only with Plasmodium. Infections with A. lumbricoides, T. trichiura and S. mansoni were positively associated with P. falciparum infection. However, further studies are required to investigate how these helminths could contribute to increased prevalence of P. falciparum infection.

Malaria and related outcomes in patients with intestinal helminths: a cross-sectional study

PubMed Central

2012-01-01

Background The effects of helminth co-infection on malaria in humans remain uncertain. This study aimed to evaluate the nature of association of intestinal helminths with prevalence and clinical outcomes of Plasmodium infection. Methods A cross-sectional study involving 1,065 malaria suspected febrile patients was conducted at Dore Bafeno Health Center, Southern Ethiopia, from December 2010 to February 2011. Plasmodium and intestinal helminth infections were diagnosed using Giemsa-stained blood films and Kato-Katz technique, respectively. Haemoglobin level was determined using a haemocue machine. Results Among 1,065 malaria suspected febrile patients, 28.8% were positive for Plasmodium parasites (P. falciparum =13.0%, P. vivax =14.5%, P. falciparum and P. vivax =1.3%). Among 702 patients who provided stool samples, 53.8%, 31.6% and 19.4% were infected with intestinal helminths, Plasmodium alone and with both Plasmodium and intestinal helminths, respectively. The prevalence of infections with Ascaris lumbricoides (A. lumbricoides), Trichuris trichiura (T. trichiura), Schistosoma mansoni (S. mansoni) and hookworm (9.8%) were 35.9%, 15.8%, 11.7% and 9.8%, respectively. Out of the 222 (31.6%) Plasmodium infected cases, 9 (4.1%) had severe malaria. P. falciparum infection was more common in febrile patients infected with A. lumbricoides alone (21.3%), T. trichiura alone (23.1%) and S. mansoni alone (23.1%) compared to those without intestinal helminth infections (9.3%) (p<0.001 for all). Prevalence of non-severe malaria was significantly higher in individuals infected with intestinal helminths than in those who were not infected with intestinal helminths (adjusted OR=1.58, 95% CI=1.13-2.22). The chance of developing non-severe P. falciparum malaria were 2.6, 2.8 and 3.3 times higher in individuals infected with A. lumbricoides alone, T. trichiura alone and S. mansoni alone, respectively, compared to intestinal helminth-free individuals (p<0.05 for all). The odds ratio for being infected with non-severe P. falciparum increased with the number of intestinal helminth species (p<0.001). Mean Plasmodium density among intestinal helminth infected individuals was significantly increased with the number of intestinal helminths species (p=0.027). Individuals who were co-infected with different species of intestinal helminths and Plasmodium showed lower mean haemoglobin concentration than individuals who were infected only with Plasmodium. Conclusions Infections with A. lumbricoides, T. trichiura and S. mansoni were positively associated with P. falciparum infection. However, further studies are required to investigate how these helminths could contribute to increased prevalence of P. falciparum infection. PMID:23136960

First case of Plasmodium knowlesi infection in a Japanese traveller returning from Malaysia.

PubMed

Tanizaki, Ryutaro; Ujiie, Mugen; Kato, Yasuyuki; Iwagami, Moritoshi; Hashimoto, Aki; Kutsuna, Satoshi; Takeshita, Nozomi; Hayakawa, Kyoko; Kanagawa, Shuzo; Kano, Shigeyuki; Ohmagari, Norio

2013-04-15

This is the first case of Plasmodium knowlesi infection in a Japanese traveller returning from Malaysia. In September 2012, a previously healthy 35-year-old Japanese man presented to National Center for Global Health and Medicine in Tokyo with a two-day history of daily fever, mild headaches and mild arthralgia. Malaria parasites were found in the Giemsa-stained thin blood smear, which showed band forms similar to Plasmodium malariae. Although a nested PCR showed the amplification of the primer of Plasmodium vivax and Plasmodium knowlesi, he was finally diagnosed with P. knowlesi mono-infection by DNA sequencing. He was treated with mefloquine, and recovered without any complications. DNA sequencing of the PCR products is indispensable to confirm P. knowlesi infection, however there is limited access to DNA sequencing procedures in endemic areas. The extent of P. knowlesi transmission in Asia has not been clearly defined. There is limited availability of diagnostic tests and routine surveillance system for reporting an accurate diagnosis in the Asian endemic regions. Thus, reporting accurately diagnosed cases of P. knowlesi infection in travellers would be important for assessing the true nature of this emerging human infection.

Exploring Anopheles gut bacteria for Plasmodium blocking activity

PubMed Central

Bahia, Ana C; Dong, Yuemei; Blumberg, Benjamin J; Mlambo, Godfree; Tripathi, Abhai; BenMarzouk-Hidalgo, Omar J; Chandra, Ramesh; Dimopoulos, George

2014-01-01

SUMMARY Malaria parasite transmission requires the successful development of Plasmodium gametocytes into flagellated microgametes upon mosquito blood ingestion, and the subsequent fertilization of microgametes and macrogametes for the development of motile zygotes, called ookinetes, which invade and transverse the Anopheles vector mosquito midgut at around 18-36 h after blood ingestion. Within the mosquito midgut, the malaria parasite has to withstand the mosquito's innate immune response and the detrimental effect of its commensal bacterial flora. We have assessed the midgut colonization capacity of 5 gut bacterial isolates from field-derived, and 2 from laboratory colony, mosquitoes and their effect on Plasmodium development in vivo and in vitro, along with their impact on mosquito survival. Some bacterial isolates activated the mosquito's immune system, affected the mosquito's life span, and were capable of blocking Plasmodium development. We have also shown that the ability of these bacteria to inhibit the parasites is likely to involve different mechanisms and factors. A Serratia marcescens isolate was particularly efficient in colonizing the mosquitoes’ gut, compromising mosquito survival, and inhibiting both sexual- and asexual-stage Plasmodium through secreted factors, thereby rendering it a potential candidate for the development of a malaria transmission intervention strategy. PMID:24428613

Genetic homogeneity of goat malaria parasites in Asia and Africa suggests their expansion with domestic goat host.

PubMed

Kaewthamasorn, Morakot; Takeda, Mika; Saiwichai, Tawee; Gitaka, Jesse N; Tiawsirisup, Sonthaya; Imasato, Yuhei; Mossaad, Ehab; Sarani, Ali; Kaewlamun, Winai; Channumsin, Manun; Chaiworakul, Suchart; Katepongpun, Wichit; Teeveerapunya, Surapong; Panthong, Jarus; Mureithi, Dominic K; Bawm, Saw; Htun, Lat Lat; Win, Mar Mar; Ismail, Ahmed Ali; Ibrahim, Abdalla Mohamed; Suganuma, Keisuke; Hakimi, Hassan; Nakao, Ryo; Katakura, Ken; Asada, Masahito; Kaneko, Osamu

2018-04-11

Plasmodium was first identified in a goat in Angola in 1923, and only recently characterized by DNA isolation from a goat blood sample in Zambia. Goats were first domesticated in the Fertile Crescent approximately 10,000 years ago, and are now globally distributed. It is not known if the Plasmodium identified in African goats originated from parasites circulating in the local ungulates, or if it co-evolved in the goat before its domestication. To address this question, we performed PCR-based surveillance using a total of 1,299 goat blood samples collected from Sudan and Kenya in Africa, Iran in west Asia, and Myanmar and Thailand in southeast Asia. Plasmodium DNA was detected from all locations, suggesting that the parasite is not limited to Africa, but widely distributed. Whole mitochondrial DNA sequences revealed that there was only one nucleotide substitution between Zambian/Kenyan samples and others, supporting the existence of a goat-specific Plasmodium species, presumably Plasmodium caprae, rather than infection of goats by local ungulate malaria parasites. We also present the first photographic images of P. caprae, from one Kenyan goat sample.

Real-time PCR detection of Plasmodium directly from whole blood and filter paper samples

PubMed Central

2011-01-01

Background Real-time PCR is a sensitive and specific method for the analysis of Plasmodium DNA. However, prior purification of genomic DNA from blood is necessary since PCR inhibitors and quenching of fluorophores from blood prevent efficient amplification and detection of PCR products. Methods Reagents designed to specifically overcome PCR inhibition and quenching of fluorescence were evaluated for real-time PCR amplification of Plasmodium DNA directly from blood. Whole blood from clinical samples and dried blood spots collected in the field in Colombia were tested. Results Amplification and fluorescence detection by real-time PCR were optimal with 40× SYBR® Green dye and 5% blood volume in the PCR reaction. Plasmodium DNA was detected directly from both whole blood and dried blood spots from clinical samples. The sensitivity and specificity ranged from 93-100% compared with PCR performed on purified Plasmodium DNA. Conclusions The methodology described facilitates high-throughput testing of blood samples collected in the field by fluorescence-based real-time PCR. This method can be applied to a broad range of clinical studies with the advantages of immediate sample testing, lower experimental costs and time-savings. PMID:21851640

Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax

PubMed Central

Talundzic, Eldin; Chenet, Stella M.; Goldman, Ira F.; Patel, Dhruviben S.; Nelson, Julia A.; Plucinski, Mateusz M.; Barnwell, John W.; Udhayakumar, Venkatachalam

2015-01-01

Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species. PMID:26292024

Avian Plasmodium infection in field-collected mosquitoes during 2012-2013 in Tarlac, Philippines.

PubMed

Chen, Tien-Huang; Aure, Wilfredo E; Cruz, Estrella Irlandez; Malbas, Fedelino F; Teng, Hwa-Jen; Lu, Liang-Chen; Kim, Kyeong Soon; Tsuda, Yoshio; Shu, Pei-Yun

2015-12-01

Global warming threatens to increase the spread and prevalence of mosquito-transmitted diseases. Certain pathogens may be carried by migratory birds and transmitted to local mosquito populations. Mosquitoes were collected in the northern Philippines during bird migration seasons to detect avian malaria parasites as well as for the identification of potential vector species and the estimation of infections among local mosquito populations. We used the nested PCR to detect the avian malaria species. Culex vishnui (47.6%) was the most abundant species collected and Cx. tritaeniorhynchus (13.8%) was the second most abundant. Avian Plasmodium parasites were found in eight mosquito species, for which the infection rates were between 0.5% and 6.2%. The six Plasmodium genetic lineages found in this study included P. juxtanucleare -GALLUS02, Tacy7 (Donana04), CXBIT01, Plasmodium species LIN2 New Zealand, and two unclassified lineages. The potential mosquito vectors for avian Plasmodium parasites in the Philippines were Cq. crassipes, Cx. fuscocephala, Cx. quinquefasciatus, Cx. sitiens, Cx. vishnui, and Ma. Uniformis; two major genetic lineages, P. juxtanucleare and Tacy7, were identified. © 2015 The Society for Vector Ecology.

Genetic Analysis and Species Specific Amplification of the Artemisinin Resistance-Associated Kelch Propeller Domain in P. falciparum and P. vivax.

PubMed

Talundzic, Eldin; Chenet, Stella M; Goldman, Ira F; Patel, Dhruviben S; Nelson, Julia A; Plucinski, Mateusz M; Barnwell, John W; Udhayakumar, Venkatachalam

2015-01-01

Plasmodium falciparum resistance to artemisinin has emerged in the Greater Mekong Subregion and now poses a threat to malaria control and prevention. Recent work has identified mutations in the kelch propeller domain of the P. falciparum K13 gene to be associated artemisinin resistance as defined by delayed parasite clearance and ex vivo ring stage survival assays. Species specific primers for the two most prevalent human malaria species, P. falciparum and P. vivax, were designed and tested on multiple parasite isolates including human, rodent, and non- humans primate Plasmodium species. The new protocol described here using the species specific primers only amplified their respective species, P. falciparum and P. vivax, and did not cross react with any of the other human malaria Plasmodium species. We provide an improved species specific PCR and sequencing protocol that could be effectively used in areas where both P. falciparum and P. vivax are circulating. To design this improved protocol, the kelch gene was analyzed and compared among different species of Plasmodium. The kelch propeller domain was found to be highly conserved across the mammalian Plasmodium species.

Identification of human Phosphatidyl Inositol 5-Phosphate 4-Kinase as an RNA binding protein that is imported into Plasmodium falciparum.

PubMed

Vindu, Arya; Dandewad, Vishal; Seshadri, Vasudevan

2018-04-06

Plasmodium falciparum is a causative agent for malaria and has a complex life cycle in human and mosquito hosts. Translation repression of specific set of mRNA has been reported in gametocyte stages of this parasite. A conserved element present in the 3'UTR of some of these transcripts was identified. Biochemical studies have identified components of the RNA storage and/or translation inhibitor complex but it is not yet clear how the complex is specifically recruited on the RNA targeted for translation regulation. We used the 3'UTR region of translationally regulated transcripts to identify Phosphatidyl-inositol 5-phosphate 4-kinase (PIP4K2A) as the protein that associates with these RNAs. We further show that recombinant PIP4K2A has the RNA binding activity and can associate specifically with Plasmodium 3'UTR RNAs. Immunostainings show that hPIP4K2A is imported into the Plasmodium parasite from RBC. These results identify a novel RNA binding role for PIP4K2A that may play a role in Plasmodium propagation. Copyright © 2018 Elsevier Inc. All rights reserved.

Cellular stress associated with the differentiation of Plasmodium berghei ookinetes.

PubMed

Duran-Bedolla, Josefina; Téllez-Sosa, Juan; Valdovinos-Torres, Humberto; Pavón, Natalia; Buelna-Chontal, Mabel; Tello-López, Angel T; Argotte-Ramos, Rocio; Rodríguez, Mario Henry; Rodríguez, María Carmen

2017-04-01

For malaria transmission, Plasmodium parasites must develop in the mosquito vector. Oxidative stress in the insect midgut, triggered by environmental changes (e.g., pH and temperature), influences the cellular signaling involved in differentiation from gametocytes to mobile ookinetes for the purpose of parasite survival. Oxidative stress activates the homeostatic response to stress characterized by the phosphorylation eIF2α, the attenuation of protein synthesis, and the transcription of genes participating in the unfolded protein response and antioxidant processes, forming a part of an integrated stress response (ISR). We hypothesized that ISR operates during the differentiation of gametocytes to ookinetes to assure Plasmodium survival. Using in-vitro conditions resembling the mosquito midgut conditions, we cultured Plasmodium berghei gametocytes to ookinetes and evaluated the redox balance by detecting reactive oxygen species and superoxide dismutase activity. Additionally, we evaluated the phosphorylation of eIF2α, the attenuation of the global protein synthesis, and the gene expression of cellular stress markers (e.g., endoplasmic reticulum chaperones and antioxidant molecules, measured by reverse-transcription quantitative polymerase chain reaction), finding that these processes were all taking place, probably to improve survival during the differentiation of Plasmodium berghei ookinetes.

An essential role of the basal body protein SAS-6 in Plasmodium male gamete development and malaria transmission

PubMed Central

Marques, Sara R; Ramakrishnan, Chandra; Carzaniga, Raffaella; Blagborough, Andrew M; Delves, Michael J; Talman, Arthur M; Sinden, Robert E

2015-01-01

Gametocytes are the sole Plasmodium parasite stages that infect mosquitoes; therefore development of functional gametes is required for malaria transmission. Flagellum assembly of the Plasmodium male gamete differs from that of most other eukaryotes in that it is intracytoplasmic but retains a key conserved feature: axonemes assemble from basal bodies. The centriole/basal body protein SAS-6 normally regulates assembly and duplication of these organelles and its depletion causes severe flagellar/ciliary abnormalities in a diverse array of eukaryotes. Since basal body and flagellum assembly are intimately coupled to male gamete development in Plasmodium, we hypothesized that SAS-6 disruption may cause gametogenesis defects and perturb transmission. We show that Plasmodium berghei sas6 knockouts display severely abnormal male gametogenesis presenting reduced basal body numbers, axonemal assembly defects and abnormal nuclear allocation. The defects in gametogenesis reduce fertilization and render Pbsas6 knockouts less infectious to mosquitoes. Additionally, we show that lack of Pbsas6 blocks transmission from mosquito to vertebrate host, revealing an additional yet undefined role in ookinete to sporulating oocysts transition. These findings underscore the vulnerability of the basal body/SAS-6 to malaria transmission blocking interventions. PMID:25154861

Origin of the human malaria parasite Plasmodium falciparum in gorillas

PubMed Central

Liu, Weimin; Li, Yingying; Learn, Gerald H.; Rudicell, Rebecca S.; Robertson, Joel D.; Keele, Brandon F.; Ndjango, Jean-Bosco N.; Sanz, Crickette M.; Morgan, David B.; Locatelli, Sabrina; Gonder, Mary K.; Kranzusch, Philip J.; Walsh, Peter D.; Delaporte, Eric; Mpoudi-Ngole, Eitel; Georgiev, Alexander V.; Muller, Martin N.; Shaw, George M.; Peeters, Martine; Sharp, Paul M.; Rayner, Julian C.; Hahn, Beatrice H.

2010-01-01

Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here, we developed a novel polymerase chain reaction based single genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in fecal samples of wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed, and almost always comprised of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas was comprised of parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla and not of chimpanzee, bonobo or ancient human origin. PMID:20864995

Comparative Genomics and Systems Biology of Malaria Parasites Plasmodium

PubMed Central

Cai, Hong; Zhou, Zhan; Gu, Jianying; Wang, Yufeng

2013-01-01

Malaria is a serious infectious disease that causes over one million deaths yearly. It is caused by a group of protozoan parasites in the genus Plasmodium. No effective vaccine is currently available and the elevated levels of resistance to drugs in use underscore the pressing need for novel antimalarial targets. In this review, we survey omics centered developments in Plasmodium biology, which have set the stage for a quantum leap in our understanding of the fundamental processes of the parasite life cycle and mechanisms of drug resistance and immune evasion. PMID:24298232

Optimized Pan-species and Speciation Duplex Real-time PCR Assays for Plasmodium Parasites Detection in Malaria Vectors

PubMed Central

Sandeu, Maurice Marcel; Moussiliou, Azizath; Moiroux, Nicolas; Padonou, Gilles G.; Massougbodji, Achille; Corbel, Vincent; Tuikue Ndam, Nicaise

2012-01-01

Background An accurate method for detecting malaria parasites in the mosquito’s vector remains an essential component in the vector control. The Enzyme linked immunosorbent assay specific for circumsporozoite protein (ELISA-CSP) is the gold standard method for the detection of malaria parasites in the vector even if it presents some limitations. Here, we optimized multiplex real-time PCR assays to accurately detect minor populations in mixed infection with multiple Plasmodium species in the African malaria vectors Anopheles gambiae and Anopheles funestus. Methods Complementary TaqMan-based real-time PCR assays that detect Plasmodium species using specific primers and probes were first evaluated on artificial mixtures of different targets inserted in plasmid constructs. The assays were further validated in comparison with the ELISA-CSP on 200 field caught Anopheles gambiae and Anopheles funestus mosquitoes collected in two localities in southern Benin. Results The validation of the duplex real-time PCR assays on the plasmid mixtures demonstrated robust specificity and sensitivity for detecting distinct targets. Using a panel of mosquito specimen, the real-time PCR showed a relatively high sensitivity (88.6%) and specificity (98%), compared to ELISA-CSP as the referent standard. The agreement between both methods was “excellent” (κ = 0.8, P<0.05). The relative quantification of Plasmodium DNA between the two Anopheles species analyzed showed no significant difference (P = 0, 2). All infected mosquito samples contained Plasmodium falciparum DNA and mixed infections with P. malariae and/or P. ovale were observed in 18.6% and 13.6% of An. gambiae and An. funestus respectively. Plasmodium vivax was found in none of the mosquito samples analyzed. Conclusion This study presents an optimized method for detecting the four Plasmodium species in the African malaria vectors. The study highlights substantial discordance with traditional ELISA-CSP pointing out the utility of employing an accurate molecular diagnostic tool for detecting malaria parasites in field mosquito populations. PMID:23285168

Simple Real-Time PCR and Amplicon Sequencing Method for Identification of Plasmodium Species in Human Whole Blood.

PubMed

Lefterova, Martina I; Budvytiene, Indre; Sandlund, Johanna; Färnert, Anna; Banaei, Niaz

2015-07-01

Malaria is the leading identifiable cause of fever in returning travelers. Accurate Plasmodium species identification has therapy implications for P. vivax and P. ovale, which have dormant liver stages requiring primaquine. Compared to microscopy, nucleic acid tests have improved specificity for species identification and higher sensitivity for mixed infections. Here, we describe a SYBR green-based real-time PCR assay for Plasmodium species identification from whole blood, which uses a panel of reactions to detect species-specific non-18S rRNA gene targets. A pan-Plasmodium 18S rRNA target is also amplified to allow species identification or confirmation by sequencing if necessary. An evaluation of assay accuracy, performed on 76 clinical samples (56 positives using thin smear microscopy as the reference method and 20 negatives), demonstrated clinical sensitivities of 95.2% for P. falciparum (20/21 positives detected) and 100% for the Plasmodium genus (52/52), P. vivax (20/20), P. ovale (9/9), and P. malariae (6/6). The sensitivity of the P. knowlesi-specific PCR was evaluated using spiked whole blood samples (100% [10/10 detected]). The specificities of the real-time PCR primers were 94.2% for P. vivax (49/52) and 100% for P. falciparum (51/51), P. ovale (62/62), P. malariae (69/69), and P. knowlesi (52/52). Thirty-three specimens were used to test species identification by sequencing the pan-Plasmodium 18S rRNA PCR product, with correct identification in all cases. The real-time PCR assay also identified two samples with mixed P. falciparum and P. ovale infection, which was confirmed by sequencing. The assay described here can be integrated into a malaria testing algorithm in low-prevalence areas, allowing definitive Plasmodium species identification shortly after malaria diagnosis by microscopy. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Submicroscopic placental infection by non-falciparum Plasmodium spp.

PubMed Central

Doritchamou, Justin Y. A.; Akuffo, Richard A.; Moussiliou, Azizath; Luty, Adrian J. F.; Massougbodji, Achille; Deloron, Philippe

2018-01-01

Background Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy. Methods and findings Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed Conclusions Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes. PMID:29432484

Self-diagnosis of malaria by travelers and expatriates: assessment of malaria rapid diagnostic tests available on the internet.

PubMed

Maltha, Jessica; Gillet, Philippe; Heutmekers, Marloes; Bottieau, Emmanuel; Van Gompel, Alfons; Jacobs, Jan

2013-01-01

In the past malaria rapid diagnostic tests (RDTs) for self-diagnosis by travelers were considered suboptimal due to poor performance. Nowadays RDTs for self-diagnosis are marketed and available through the internet. The present study assessed RDT products marketed for self-diagnosis for diagnostic accuracy and quality of labeling, content and instructions for use (IFU). Diagnostic accuracy of eight RDT products was assessed with a panel of stored whole blood samples comprising the four Plasmodium species (n = 90) as well as Plasmodium negative samples (n = 10). IFUs were assessed for quality of description of procedure and interpretation and for lay-out and readability level. Errors in packaging and content were recorded. Two products gave false-positive test lines in 70% and 80% of Plasmodium negative samples, precluding their use. Of the remaining products, 4/6 had good to excellent sensitivity for the diagnosis of Plasmodium falciparum (98.2%-100.0%) and Plasmodium vivax (93.3%-100.0%). Sensitivity for Plasmodium ovale and Plasmodium malariae diagnosis was poor (6.7%-80.0%). All but one product yielded false-positive test lines after reading beyond the recommended reading time. Problems with labeling (not specifying target antigens (n = 3), and content (desiccant with no humidity indicator (n = 6)) were observed. IFUs had major shortcomings in description of test procedure and interpretation, poor readability and lay-out and user-unfriendly typography. Strategic issues (e.g. the need for repeat testing and reasons for false-negative tests) were not addressed in any of the IFUs. Diagnostic accuracy of RDTs for self-diagnosis was variable, with only 4/8 RDT products being reliable for the diagnosis of P. falciparum and P. vivax, and none for P. ovale and P. malariae. RDTs for self-diagnosis need improvements in IFUs (content and user-friendliness), labeling and content before they can be considered for self-diagnosis by the traveler.

Self-Diagnosis of Malaria by Travelers and Expatriates: Assessment of Malaria Rapid Diagnostic Tests Available on the Internet

PubMed Central

Maltha, Jessica; Gillet, Philippe; Heutmekers, Marloes; Bottieau, Emmanuel; Van Gompel, Alfons; Jacobs, Jan

2013-01-01

Introduction In the past malaria rapid diagnostic tests (RDTs) for self-diagnosis by travelers were considered suboptimal due to poor performance. Nowadays RDTs for self-diagnosis are marketed and available through the internet. The present study assessed RDT products marketed for self-diagnosis for diagnostic accuracy and quality of labeling, content and instructions for use (IFU). Methods Diagnostic accuracy of eight RDT products was assessed with a panel of stored whole blood samples comprising the four Plasmodium species (n = 90) as well as Plasmodium negative samples (n = 10). IFUs were assessed for quality of description of procedure and interpretation and for lay-out and readability level. Errors in packaging and content were recorded. Results Two products gave false-positive test lines in 70% and 80% of Plasmodium negative samples, precluding their use. Of the remaining products, 4/6 had good to excellent sensitivity for the diagnosis of Plasmodium falciparum (98.2%–100.0%) and Plasmodium vivax (93.3%–100.0%). Sensitivity for Plasmodium ovale and Plasmodium malariae diagnosis was poor (6.7%–80.0%). All but one product yielded false-positive test lines after reading beyond the recommended reading time. Problems with labeling (not specifying target antigens (n = 3), and content (desiccant with no humidity indicator (n = 6)) were observed. IFUs had major shortcomings in description of test procedure and interpretation, poor readability and lay-out and user-unfriendly typography. Strategic issues (e.g. the need for repeat testing and reasons for false-negative tests) were not addressed in any of the IFUs. Conclusion Diagnostic accuracy of RDTs for self-diagnosis was variable, with only 4/8 RDT products being reliable for the diagnosis of P. falciparum and P. vivax, and none for P. ovale and P. malariae. RDTs for self-diagnosis need improvements in IFUs (content and user-friendliness), labeling and content before they can be considered for self-diagnosis by the traveler. PMID:23301027

Description of the first cryptic avian malaria parasite, Plasmodium homocircumflexum n. sp., with experimental data on its virulence and development in avian hosts and mosquitoes.

PubMed

Palinauskas, Vaidas; Žiegytė, Rita; Ilgūnas, Mikas; Iezhova, Tatjana A; Bernotienė, Rasa; Bolshakov, Casimir; Valkiūnas, Gediminas

2015-01-01

For over 100 years studies on avian haemosporidian parasite species have relied on similarities in their morphology to establish a species concept. Some exceptional cases have also included information about the life cycle and sporogonic development. More than 50 avian Plasmodium spp. have now been described. However, PCR-based studies show a much broader diversity of haemosporidian parasites, indicating the possible existence of a diverse group of cryptic species. In the present study, using both similarity and phylogenetic species definition concepts, we believe that we report the first characterised cryptic speciation case of an avian Plasmodium parasite. We used sequence information on the mitochondrial cytochrome b gene and constructed phylogenies of identified Plasmodium spp. to define their position in the phylogenetic tree. After analysis of blood stages, the morphology of the parasite was shown to be identical to Plasmodium circumflexum. However, the geographic distribution of the new parasite, the phylogenetic information, as well as patterns of development of infection, indicate that this parasite differs from P. circumflexum. Plasmodium homocircumflexum n. sp. was described based on information about genetic differences from described lineages, phylogenetic position and biological characters. This parasite develops parasitemia in experimentally infected birds - the domestic canary Serinus canaria domestica, siskin Carduelis spinus and crossbill Loxia curvirostra. Anaemia caused by high parasitemia, as well as cerebral paralysis caused by exoerythrocytic stages in the brain, are the main reasons for mortality. Exoerythrocytic stages also form in other organs (heart, kidneys, liver, lungs, spleen, intestines and pectoral muscles). DNA amplification was unsuccessful from faecal samples of heavily infected birds. The sporogonic development initiates, but is abortive, at the oocyst stage in two common European mosquito species, Culex pipiens pipiens (forms pipiens and molestus) and Aedes vexans. Vectors of this Plasmodium sp. remain unknown. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Utility of nested polymerase chain reaction over the microscopy and immuno-chromatographic test in the detection of Plasmodium species and their clinical spectrum.

PubMed

Ranjan, P; Ghoshal, U

2016-09-01

Though demonstration of Plasmodium parasite in peripheral blood on microscopy remains gold standard, it may miss some patients resulting in delay in instituting life-saving therapy. Studies on polymerase chain reaction (PCR), a highly sensitive and specific technique that also discriminates among different species of malaria parasite, are scanty. Hence, we aimed to evaluate the role of PCR in diagnosis and species identification of Plasmodium. Of 2186 febrile patients with clinical suspicion of malaria screened between July 2013 to February 2015, 561 patients fulfilled inclusion criteria. Microscopy, rapid diagnostic test (RDT) and PCR were performed to identify the parasite. Plasmodium was detected in 64/561 (11.40 %), 92/561 (16.40 %) and 78/561 (13.90 %) cases using microscopy, RDT and PCR, respectively. Of 78 positive cases by PCR, 47 (60.25 %) were confirmed as Plasmodium falciparum (P. falciparum), 28 (35.89 %) were Plasmodium vivax (P. vivax) and 3 (3.84 %) had mixed infections. Sensitivity and specificity of microscopy and RDT were 82.10 %, 100 % and 98.70 %, 96.90 %, respectively (p = 0.139). Of total 93 patients, 67 (72.04 %) were classified as complicated and 26 (27.96 %) were as uncomplicated. Creatinine (p = <0.001), conjugated bilirubin (p = 0.003) and total bilirubin (p = <0.001) level was elevated in complicated malaria along with renal (65 %) and liver dysfunction (25 %). In the present study, P. falciparum was responsible for 40/67 (59.70 %) cases of complicated malaria; P. vivax was also found in 17/67 (25.37 %) complicated cases using PCR. The findings highlight the alarming number of complicated vivax malaria in addition to falciparum. Moreover, PCR proved to be highly sensitive and specific test for detecting Plasmodium species.

Erythrocytic Adenosine Monophosphate as an Alternative Purine Source in Plasmodium falciparum*

PubMed Central

Cassera, María B.; Hazleton, Keith Z.; Riegelhaupt, Paul M.; Merino, Emilio F.; Luo, Minkui; Akabas, Myles H.; Schramm, Vern L.

2008-01-01

Plasmodium falciparum is a purine auxotroph, salvaging purines from erythrocytes for synthesis of RNA and DNA. Hypoxanthine is the key precursor for purine metabolism in Plasmodium. Inhibition of hypoxanthine-forming reactions in both erythrocytes and parasites is lethal to cultured P. falciparum. We observed that high concentrations of adenosine can rescue cultured parasites from purine nucleoside phosphorylase and adenosine deaminase blockade but not when erythrocyte adenosine kinase is also inhibited. P. falciparum lacks adenosine kinase but can salvage AMP synthesized in the erythrocyte cytoplasm to provide purines when both human and Plasmodium purine nucleoside phosphorylases and adenosine deaminases are inhibited. Transport studies in Xenopus laevis oocytes expressing the P. falciparum nucleoside transporter PfNT1 established that this transporter does not transport AMP. These metabolic patterns establish the existence of a novel nucleoside monophosphate transport pathway in P. falciparum. PMID:18799466

Identification of the five human Plasmodium species including P. knowlesi by real-time polymerase chain reaction.

PubMed

Oddoux, O; Debourgogne, A; Kantele, A; Kocken, C H; Jokiranta, T S; Vedy, S; Puyhardy, J M; Machouart, M

2011-04-01

Recently, Plasmodium knowlesi has been recognised as the fifth Plasmodium species causing malaria in humans. Hundreds of human cases infected with this originally simian Plasmodium species have been described in Asian countries and increasing numbers are reported in Europe from travellers. The growing impact of tourism and economic development in South and Southeast Asia are expected to subsequently lead to a further increase in cases both among locals and among travellers. P. knowlesi is easily misidentified in microscopy as P. malariae or P. falciparum. We developed new primers for the rapid and specific detection of this species by low-cost real-time polymerase chain reaction (PCR) and added this method to an already existing panel of primers used for the molecular identification of the other four species in one reaction. Reference laboratories should now be able to identify undisputably and rapidly P. knowlesi, as it is a potentially fatal pathogen.

Plasmodium berghei ANKA (PbA) infection of C57BL/6J mice: a model of severe malaria.

PubMed

de Oca, Marcela Montes; Engwerda, Christian; Haque, Ashraful

2013-01-01

The term "severe malaria" refers to a wide spectrum of syndromes in Plasmodium-infected humans including cerebral malaria (CM), respiratory distress, severe anemia, liver dysfunction, and hypoglycemia. Mouse models have been employed to further our understanding of the pathology and immune responses that occur during Plasmodium infection. Evidence of brain, liver, lung, and spleen pathology, as well as anemia and tissue-sequestration of parasites, has been reported in various strains of inbred mice. While no single mouse model mimics all the various clinical manifestations of severe malaria in humans, here we describe a detailed protocol for Plasmodium berghei ANKA infection of C57BL/6J mice. For many years, this model has been referred to as "experimental cerebral malaria," but in fact recapitulates many of the symptoms and pathologies observed in most severe malaria syndromes.

Light irradiation induces fragmentation of the plasmodium, a novel photomorphogenesis in the true slime mold Physarum polycephalum: action spectra and evidence for involvement of the phytochrome.

PubMed

Kakiuchi, Y; Takahashi, T; Murakami, A; Ueda, T

2001-03-01

A new photomorphogenesis was found in the plasmodium of the true slime mold Physarum polycephalum: the plasmodium broke temporarily into equal-sized spherical pieces, each containing about eight nuclei, about 5 h after irradiation with light. Action spectroscopic study showed that UVA, blue and far-red lights were effective, while red light inhibited the far-red-induced fragmentation. Difference absorption spectra of both the living plasmodium and the plasmodial homogenate after alternate irradiation with far-red and red light gave two extremes at 750 and 680 nm, which agreed with those for the induction and inhibition of the fragmentation, respectively. A kinetic model similar to that of phytochrome action explained quantitatively the fluence rate-response curves of the fragmentation. Our results indicate that one of the photoreceptors for the plasmodial fragmentation is a phytochrome.

Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice.

PubMed

Soulard, Valérie; Bosson-Vanga, Henriette; Lorthiois, Audrey; Roucher, Clémentine; Franetich, Jean-François; Zanghi, Gigliola; Bordessoulles, Mallaury; Tefit, Maurel; Thellier, Marc; Morosan, Serban; Le Naour, Gilles; Capron, Frédérique; Suemizu, Hiroshi; Snounou, Georges; Moreno-Sabater, Alicia; Mazier, Dominique

2015-07-24

Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans.

Epidemic Distribution and Variation of Plasmodium falciparum and Plasmodium vivax Malaria in Hainan, China during 1995–2008

PubMed Central

Xiao, Dan; Long, Yong; Wang, Shanqing; Wu, Kejian; Xu, Dezhong; Li, Haitao; Wang, Guangze; Yan, Yongping

2012-01-01

Hainan Province is the main area threatened by malaria in China. However, the epidemiologic patterns of malaria in this region are not yet defined. In this study, we determined the spatio-temporal distribution and variation of Plasmodium falciparum and Plasmodium vivax malaria in Hainan during 1995–2008 by using wavelet and cluster quantitative approaches. The results indicated a decreasing secular trend and obvious seasonal fluctuation of malaria in Hainan. In addition, the characteristic annual peak of malaria could not be detected after 2005. The southcentral region of Hainan has remained an area of relatively high malaria risk, but the incidence of P. falciparum malaria increased significantly in the southeast and southwest regions during 2002–2008. These findings identify epidemic patterns of malaria in Hainan, and are applicable for designing an effective and dynamic public health campaign to combat malaria in this region. PMID:22869636

Plasmodium knowlesi malaria during pregnancy.

PubMed

Barber, Bridget E; Bird, Elspeth; Wilkes, Christopher S; William, Timothy; Grigg, Matthew J; Paramaswaran, Uma; Menon, Jayaram; Jelip, Jenarun; Yeo, Tsin W; Anstey, Nicholas M

2015-04-01

Plasmodium knowlesi is the commonest cause of malaria in Malaysia, but little is known regarding infection during pregnancy. To investigate comparative risk and consequences of knowlesi malaria during pregnancy, we reviewed (1) Sabah Health Department malaria-notification records created during 2012-2013, (2) prospectively collected data from all females with polymerase chain reaction (PCR)-confirmed malaria who were admitted to a Sabah tertiary care referral hospital during 2011-2014, and (3) malaria microscopy and clinical data recorded at a Sabah tertiary care women and children's hospital during 2010-2014. During 2012-2013, 774 females with microscopy-diagnosed malaria were notified, including 252 (33%), 172 (20%), 333 (43%), and 17 (2%) with Plasmodium falciparum infection, Plasmodium vivax infection, Plasmodium malariae/Plasmodium knowlesi infection, and mixed infection, respectively. Among females aged 15-45 years, pregnancy was reported in 18 of 124 (14.5%), 9 of 93 (9.7%), and 4 of 151 (2.6%) P. falciparum, P. vivax, and P. malariae/P. knowlesi notifications respectively (P = .002). Three females with knowlesi malaria were confirmed as pregnant: 2 had moderate anemia, and 1 delivered a preterm low-birth-weight infant. There were 17, 7, and 0 pregnant women with falciparum, vivax, and knowlesi malaria, respectively, identified from the 2 referral hospitals. Although P. knowlesi is the commonest malaria species among females in Sabah, P. knowlesi infection is relatively rare during pregnancy. It may however be associated with adverse maternal and pregnancy outcomes. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

An Impossible Journey? The Development of Plasmodium falciparum NF54 in Culex quinquefasciatus

PubMed Central

Knöckel, Julia; Molina-Cruz, Alvaro; Fischer, Elizabeth; Muratova, Olga; Haile, Ashley; Barillas-Mury, Carolina; Miller, Louis H.

2013-01-01

Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species–among them culicines (Culex spp., Aedes spp.)–present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito’s immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito’s blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph. PMID:23658824

Bioinformatics analysis for structure and function of CPR of Plasmodium falciparum.

PubMed

Fan, Zhigang; Zhang, Lingmin; Yan, Guogang; Wu, Qiang; Gan, Xiufeng; Zhong, Saifeng; Lin, Guifen

2011-02-01

To analyse the structure and function of NADPH-cytochrome p450 reductase (CYPOR or CPR) from Plasmodium falciparum (Pf), and to predict its' drug target and vaccine target. The structure, function, drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods. PfCPR, which was older CPR, had close relationship with the CPR from other Plasmodium species, but it was distant from its hosts, such as Homo sapiens and Anopheles. PfCPR was located in the cellular nucleus of Plasmodium falciparum. 335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane, while 151aa-265aa was located in the nucleolus organizer regions. PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence. The teriary structure of 1aa-700aa was forcep-shaped with wings. 15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein. These segments had 25 protein-protein binding sites. While 13 other segments all possessed function sites. The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens. PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes. PfCPR is unsuitable as vaccine target, but it has at least 13 ideal drug targets. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Non-invasive surveillance for Plasmodium in reservoir macaque species.

PubMed

Siregar, Josephine E; Faust, Christina L; Murdiyarso, Lydia S; Rosmanah, Lis; Saepuloh, Uus; Dobson, Andrew P; Iskandriati, Diah

2015-10-12

Primates are important reservoirs for human diseases, but their infection status and disease dynamics are difficult to track in the wild. Within the last decade, a macaque malaria, Plasmodium knowlesi, has caused disease in hundreds of humans in Southeast Asia. In order to track cases and understand zoonotic risk, it is imperative to be able to quantify infection status in reservoir macaque species. In this study, protocols for the collection of non-invasive samples and isolation of malaria parasites from naturally infected macaques are optimized. Paired faecal and blood samples from 60 Macaca fascicularis and four Macaca nemestrina were collected. All animals came from Sumatra or Java and were housed in semi-captive breeding colonies around West Java. DNA was extracted from samples using a modified protocol. Nested polymerase chain reactions (PCR) were run to detect Plasmodium using primers targeting mitochondrial DNA. Sensitivity of screening faecal samples for Plasmodium was compared to other studies using Kruskal Wallis tests and logistic regression models. The best primer set was 96.7 % (95 % confidence intervals (CI): 83.3-99.4 %) sensitive for detecting Plasmodium in faecal samples of naturally infected macaques (n = 30). This is the first study to produce definitive estimates of Plasmodium sensitivity and specificity in faecal samples from naturally infected hosts. The sensitivity was significantly higher than some other studies involving wild primates. Faecal samples can be used for detection of malaria infection in field surveys of macaques, even when there are no parasites visible in thin blood smears. Repeating samples from individuals will improve inferences of the epidemiology of malaria in wild primates.

Small Molecule Screen for Candidate Antimalarials Targeting Plasmodium Kinesin-5*

PubMed Central

Liu, Liqiong; Richard, Jessica; Kim, Sunyoung; Wojcik, Edward J.

2014-01-01

Plasmodium falciparum and vivax are responsible for the majority of malaria infections worldwide, resulting in over a million deaths annually. Malaria parasites now show measured resistance to all currently utilized drugs. Novel antimalarial drugs are urgently needed. The Plasmodium Kinesin-5 mechanoenzyme is a suitable “next generation” target. Discovered via small molecule screen experiments, the human Kinesin-5 has multiple allosteric sites that are “druggable.” One site in particular, unique in its sequence divergence across all homologs in the superfamily and even within the same family, exhibits exquisite drug specificity. We propose that Plasmodium Kinesin-5 shares this allosteric site and likewise can be targeted to uncover inhibitors with high specificity. To test this idea, we performed a screen for inhibitors selective for Plasmodium Kinesin-5 ATPase activity in parallel with human Kinesin-5. Our screen of nearly 2000 compounds successfully identified compounds that selectively inhibit both P. vivax and falciparum Kinesin-5 motor domains but, as anticipated, do not impact human Kinesin-5 activity. Of note is a candidate drug that did not biochemically compete with the ATP substrate for the conserved active site or disrupt the microtubule-binding site. Together, our experiments identified MMV666693 as a selective allosteric inhibitor of Plasmodium Kinesin-5; this is the first identified protein target for the Medicines of Malaria Venture validated collection of parasite proliferation inhibitors. This work demonstrates that chemical screens against human kinesins are adaptable to homologs in disease organisms and, as such, extendable to strategies to combat infectious disease. PMID:24737313

Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes

PubMed Central

Ferguson, David J. P.; Kaindama, Mbinda L.; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, Zineb; Brady, Declan; Guttery, David S.; Wheatley, Sally P.; Yamano, Hiroyuki; Holder, Anthony A.; Pain, Arnab; Wickstead, Bill; Tewari, Rita

2015-01-01

Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei. PMID:26565797

Deaths due to Plasmodium knowlesi malaria in Sabah, Malaysia: association with reporting as Plasmodium malariae and delayed parenteral artesunate

PubMed Central

2012-01-01

Background The simian parasite Plasmodium knowlesi is recognized as a common cause of severe and fatal human malaria in Sabah, Malaysia, but is morphologically indistinguishable from and still commonly reported as Plasmodium malariae, despite the paucity of this species in Sabah. Since December 2008 Sabah Department of Health has recommended intravenous artesunate and referral to a general hospital for all severe malaria cases of any species. This paper reviews all malaria deaths in Sabah subsequent to the introduction of these measures. Reporting of malaria deaths in Malaysia is mandatory. Methods Details of reported malaria deaths during 2010-2011 were reviewed to determine the proportion of each Plasmodium species. Demographics, clinical presentations and management of severe malaria caused by each species were compared. Results Fourteen malaria deaths were reported, comprising seven Plasmodium falciparum, six P. knowlesi and one Plasmodium vivax (all PCR-confirmed). Of the six P. knowlesi deaths, five were attributable to knowlesi malaria and one was attributable to P. knowlesi-associated enterobacter sepsis. Patients with directly attributable P. knowlesi deaths (N = 5) were older than those with P. falciparum (median age 51 [IQR 50-65] vs 22 [IQR 9-55] years, p = 0.06). Complications in fatal P. knowlesi included respiratory distress (N = 5, 100%), hypotension (N = 4, 80%), and renal failure (N = 4, 80%). All patients with P. knowlesi were reported as P. malariae by microscopy. Only two of five patients with severe knowlesi malaria on presentation received immediate parenteral anti-malarial treatment. The patient with P. vivax-associated severe illness did not receive parenteral treatment. In contrast six of seven patients with severe falciparum malaria received immediate parenteral treatment. Conclusion Plasmodium knowlesi was responsible, either directly or through gram-negative bacteraemia, for almost half of malaria deaths in Sabah. Patients with severe non-falciparum malaria were less likely to receive immediate parenteral therapy. This highlights the need in Sabah for microscopically diagnosed P. malariae to be reported as P. knowlesi to improve recognition and management of this potentially fatal species. Clinicians need to be better informed of the potential for severe and fatal malaria from non-falciparum species, and the need to treat all severe malaria with immediate intravenous artesunate. PMID:22905799

High prevalence of malaria in a non-endemic setting: comparison of diagnostic tools and patient outcome during a four-year survey (2013-2017).

PubMed

Calderaro, Adriana; Piccolo, Giovanna; Montecchini, Sara; Buttrini, Mirko; Rossi, Sabina; Dell'Anna, Maria Loretana; De Remigis, Valeria; Arcangeletti, Maria Cristina; Chezzi, Carlo; De Conto, Flora

2018-02-05

Malaria is no longer endemic in Italy since 1970 when the World Health Organization declared Italy malaria-free, but it is now the most commonly imported disease. The aim of the study was to analyse the trend of imported malaria cases in Parma, Italy, during January 2013-June 2017, reporting also the treatment and the outcome of cases, exploring the comparison of the three diagnostic tests used for malaria diagnosis: microscopy, immunochromatographic assay (ICT) (BinaxNOW ® ) and Real-time PCR assays detecting Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale curtisi, Plasmodium ovale wallikeri, and Plasmodium knowlesi. Of the 288 patients with suspected malaria, 87 were positive by microscopy: 73 P. falciparum, 2 P. vivax, 8 P. ovale, 1 P. vivax/P. ovale, 1 P. malariae and 2 Plasmodium sp. All samples were positive by ICT except 6. Plasmodial DNA was revealed in the 87 cases and in 2 additional cases showing P. falciparum-specific bands by ICT, as follows: 75 P. falciparum, 2 P. vivax, 6 P. ovale curtisi, 3 P. ovale wallikeri, 1 P. malariae, and 2 mixed infections. 72 patients were foreigners and 17 Italians travelling for tourism or business. The majority of these patients presented with fever at blood collection and did not have chemoprophylaxis. No fatal cases were observed and the drug mostly used was quinine observing a negative blood smear or a parasitaemia < 0.001% after 48-72 h' therapy. The study shows an update and a thorough analysis of imported malaria cases in the area of Parma during 4.5 years from the point of view of the total case management, clinical and diagnostic. The prevalence of malaria in such area in the considered period was especially due to immigrants mostly from Africa. Molecular methods were more sensitive and specific than microscopy and ICT, both detecting additional cases of P. falciparum malaria missed by microscopy and correctly identifying the Plasmodium species of medical interest. The data reported in this study may stimulate the clinicians in non-endemic areas to suspect malaria also in cases, where the most typical symptoms are absent, and the parasitologists to confirm the results of microscopy, remaining the reference method, with molecular methods to avoid misdiagnosis.

Probable chloroquine-resistant Plasmodium falciparum malaria from Mozambique A case report.

PubMed

Pillay, N; Bhoola, R L

1975-08-16

A female patient with Plasmodium falciparum malaria apparently resistant to chloroquine is descirbed. She had recently returned from Mozambique, which may prove to be a new endemic are with resistant strains. The infection was successfully treated with quinine.

In Vitro Activity of wALADin Benzimidazoles against Different Life Cycle Stages of Plasmodium Parasites

PubMed Central

Lentz, Christian S.; Sattler, Julia M.; Fendler, Martina; Gottwalt, Simon; Halls, Victoria S.; Strassel, Silke; Arriens, Sandra; Hannam, Jeffrey S.; Specht, Sabine; Famulok, Michael; Mueller, Ann-Kristin; Hoerauf, Achim

2014-01-01

wALADin1 benzimidazoles are specific inhibitors of δ-aminolevulinic acid dehydratase from Wolbachia endobacteria of filarial nematodes. We report that wALADin1 and two derivatives killed blood stage Plasmodium falciparum in vitro (50% inhibitory concentrations, 39, 7.7, and 12.8 μM, respectively). One of these derivatives inhibited gliding motility of Plasmodium berghei ANKA infectious sporozoites with nanomolar affinity and blocked invasion into hepatocytes but did not affect intrahepatocytic replication. Hence, wALADin1 benzimidazoles are tools to study gliding motility and potential antiplasmodial drug candidates. PMID:25313210

Plasmodium and mononuclear phagocytes.

PubMed

Mac-Daniel, Laura; Ménard, Robert

2015-01-01

Plasmodium, the causative agent of malaria, initially multiplies inside liver cells and then in successive cycles inside erythrocytes, causing the symptoms of the disease. In this review, we discuss interactions between the extracellular and intracellular forms of the Plasmodium parasite and innate immune cells in the mammalian host, with a special emphasis on mononuclear phagocytes. We overview here what is known about the innate immune cells that interact with parasites, mechanisms used by the parasite to evade them, and the protective or detrimental contribution of these interactions on parasite progression through its life cycle and pathology in the host. Copyright © 2014 Elsevier Ltd. All rights reserved.

The role of cGMP signalling in regulating life cycle progression of Plasmodium.

PubMed

Hopp, Christine S; Bowyer, Paul W; Baker, David A

2012-08-01

The 3'-5'-cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) is the main mediator of cGMP signalling in the malaria parasite. This article reviews the role of PKG in Plasmodium falciparum during gametogenesis and blood stage schizont rupture, as well as the role of the Plasmodium berghei orthologue in ookinete differentiation and motility, and liver stage schizont development. The current views on potential effector proteins downstream of PKG and the mechanisms that may regulate cyclic nucleotide levels are presented. Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Glucose-6-phosphate metabolism in Plasmodium falciparum.

PubMed

Preuss, Janina; Jortzik, Esther; Becker, Katja

2012-07-01

Malaria is still one of the most threatening diseases worldwide. The high drug resistance rates of malarial parasites make its eradication difficult and furthermore necessitate the development of new antimalarial drugs. Plasmodium falciparum is responsible for severe malaria and therefore of special interest with regard to drug development. Plasmodium parasites are highly dependent on glucose and very sensitive to oxidative stress; two observations that drew interest to the pentose phosphate pathway (PPP) with its key enzyme glucose-6-phosphate dehydrogenase (G6PD). A central position of the PPP for malaria parasites is supported by the fact that human G6PD deficiency protects to a certain degree from malaria infections. Plasmodium parasites and the human host possess a complete PPP, both of which seem to be important for the parasites. Interestingly, there are major differences between parasite and human G6PD, making the enzyme of Plasmodium a promising target for antimalarial drug design. This review gives an overview of the current state of research on glucose-6-phosphate metabolism in P. falciparum and its impact on malaria infections. Moreover, the unique characteristics of the enzyme G6PD in P. falciparum are discussed, upon which its current status as promising target for drug development is based. Copyright © 2012 Wiley Periodicals, Inc.

Plasmodium berghei EXP-1 interacts with host Apolipoprotein H during Plasmodium liver-stage development

PubMed Central

Sá e Cunha, Cláudia; Nyboer, Britta; Heiss, Kirsten; Sanches-Vaz, Margarida; Fontinha, Diana; Wiedtke, Ellen; Grimm, Dirk; Przyborski, Jude Marek; Mota, Maria M.; Prudêncio, Miguel; Mueller, Ann-Kristin

2017-01-01

The first, obligatory replication phase of malaria parasite infections is characterized by rapid expansion and differentiation of single parasites in liver cells, resulting in the formation and release of thousands of invasive merozoites into the bloodstream. Hepatic Plasmodium development occurs inside a specialized membranous compartment termed the parasitophorous vacuole (PV). Here, we show that, during the parasite’s hepatic replication, the C-terminal region of the parasitic PV membrane protein exported protein 1 (EXP-1) binds to host Apolipoprotein H (ApoH) and that this molecular interaction plays a pivotal role for successful Plasmodium liver-stage development. Expression of a truncated EXP-1 protein, missing the specific ApoH interaction site, or down-regulation of ApoH expression in either hepatic cells or mouse livers by RNA interference resulted in impaired intrahepatic development. Furthermore, infection of mice with sporozoites expressing a truncated version of EXP-1 resulted in both a significant reduction of liver burden and delayed blood-stage patency, leading to a disease outcome different from that generally induced by infection with wild-type parasites. This study identifies a host–parasite protein interaction during the hepatic stage of infection by Plasmodium parasites. The identification of such vital interactions may hold potential toward the development of novel malaria prevention strategies. PMID:28137845

A Novel Model of Asymptomatic Plasmodium Parasitemia That Recapitulates Elements of the Human Immune Response to Chronic Infection

PubMed Central

Baccarella, Alyssa; Craft, Joshua F.; Boyle, Michelle J.; McIntyre, Tara I.; Wood, Matthew D.; Thorn, Kurt S.; Anidi, Chioma; Bayat, Aqieda; Chung, Me Ree; Hamburger, Rebecca; Kim, Chris Y.; Pearman, Emily; Pham, Jennifer; Tang, Jia J.; Boon, Louis; Kamya, Moses R.; Dorsey, Grant; Feeney, Margaret E.; Kim, Charles C.

2016-01-01

In humans, immunity to Plasmodium sp. generally takes the form of protection from symptomatic malaria (i.e., 'clinical immunity') rather than infection ('sterilizing immunity'). In contrast, mice infected with Plasmodium develop sterilizing immunity, hindering progress in understanding the mechanistic basis of clinical immunity. Here we present a novel model in which mice persistently infected with P. chabaudi exhibit limited clinical symptoms despite sustaining patent parasite burdens for many months. Characterization of immune responses in persistently infected mice revealed development of CD4+ T cell exhaustion, increased production of IL-10, and expansion of B cells with an atypical surface phenotype. Additionally, persistently infected mice displayed a dramatic increase in circulating nonclassical monocytes, a phenomenon that we also observed in humans with both chronic Plasmodium exposure and asymptomatic infection. Following pharmacological clearance of infection, previously persistently infected mice could not control a secondary challenge, indicating that persistent infection disrupts the sterilizing immunity that typically develops in mouse models of acute infection. This study establishes an animal model of asymptomatic, persistent Plasmodium infection that recapitulates several central aspects of the immune response in chronically exposed humans. As such, it provides a novel tool for dissection of immune responses that may prevent development of sterilizing immunity and limit pathology during infection. PMID:27583554

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments.

PubMed

Srivastava, Anubhav; Philip, Nisha; Hughes, Katie R; Georgiou, Konstantina; MacRae, James I; Barrett, Michael P; Creek, Darren J; McConville, Malcolm J; Waters, Andrew P

2016-12-01

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design.

Widespread occurrence of lysine methylation in Plasmodium falciparum proteins at asexual blood stages.

PubMed

Kaur, Inderjeet; Zeeshan, Mohammad; Saini, Ekta; Kaushik, Abhinav; Mohmmed, Asif; Gupta, Dinesh; Malhotra, Pawan

2016-10-20

Post-transcriptional and post-translational modifications play a major role in Plasmodium life cycle regulation. Lysine methylation of histone proteins is well documented in several organisms, however in recent years lysine methylation of proteins outside histone code is emerging out as an important post-translational modification (PTM). In the present study we have performed global analysis of lysine methylation of proteins in asexual blood stages of Plasmodium falciparum development. We immunoprecipitated stage specific Plasmodium lysates using anti-methyl lysine specific antibodies that immunostained the asexual blood stage parasites. Using liquid chromatography and tandem mass spectrometry analysis, 570 lysine methylated proteins at three different blood stages were identified. Analysis of the peptide sequences identified 605 methylated sites within 422 proteins. Functional classification of the methylated proteins revealed that the proteins are mainly involved in nucleotide metabolic processes, chromatin organization, transport, homeostatic processes and protein folding. The motif analysis of the methylated lysine peptides reveals novel motifs. Many of the identified lysine methylated proteins are also interacting partners/substrates of PfSET domain proteins as revealed by STRING database analysis. Our findings suggest that the protein methylation at lysine residues is widespread in Plasmodium and plays an important regulatory role in diverse set of the parasite pathways.

Genomics and epigenetics of sexual commitment in Plasmodium.

PubMed

Bechtsi, D P; Waters, A P

2017-06-01

Malaria is the disease caused by the apicomplexan parasites belonging to the genus Plasmodium. Expanding our arsenal to include transmission-blocking agents in our fight against malaria is becoming increasingly important. Such an implementation requires detailed understanding of the biology of the Plasmodium life cycle stages that are transmissible. Plasmodium gametocytes are the only parasite stage that can be transmitted to the mosquito vector and are the product of sexual development in a small percentage of parasites that continually proliferate in host blood. The critical decision made by asexual erythrocytic stages to cease further proliferation and differentiate into gametocytes, as well as the first steps they take into maturity, have long remained unknown. Recent studies have contributed to a breakthrough in our understanding of this branch point in development. In this review, we will discuss the findings that have allowed us to make this major leap forward in our knowledge of sexual commitment in Plasmodium. We will further propose a model for the mechanism triggering the switch to sexual development, constructed around the proteins currently known to regulate this process. Further insight into sexual commitment and gametocyte development will help identify targets for the development of transmission-blocking malaria therapies. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

The Plasmodium protein P113 supports efficient sporozoite to liver stage conversion in vivo.

PubMed

Offeddu, Vittoria; Rauch, Manuel; Silvie, Olivier; Matuschewski, Kai

2014-02-01

Invasive stages of Plasmodium parasites possess distinct integral and peripheral membrane proteins that mediate host cell attachment and invasion. P113 is an abundant protein in detergent-resistant high molecular weight complexes in Plasmodium schizonts, but is unusual since expression extends to gametocytes and sporozoites. In this study, we tested whether P113 performs important functions for parasite propagation in Plasmodium berghei. We show that pre-erythrocytic expression of P113 displays key signatures of upregulated in infectious sporozoites (UIS) genes, including control by the liver stage master regulator SLARP. Targeted gene deletion resulted in viable blood stage parasites that displayed no signs of blood stage growth defects. p113(-) parasites propagated normally through the life cycle until mature sporozoites, but displayed defects during natural sporozoite transmission, leading to a delay to patency in infected animals. By comparative in vitro and in vivo analysis of pre-erythrocytic development and using a xeno-diagnostic test we show that ablation of P113 results in lower sporozoite to liver stage conversion and, as a consequence, reduced merozoite output in vivo, without delaying liver stage development. We conclude that p113 is dispensable for Plasmodium life cycle progression and plays auxiliary roles during pre-erythrocytic development. Copyright © 2014 Elsevier B.V. All rights reserved.

Stage-Specific Changes in Plasmodium Metabolism Required for Differentiation and Adaptation to Different Host and Vector Environments

PubMed Central

Srivastava, Anubhav; Philip, Nisha; Hughes, Katie R.; Georgiou, Konstantina; MacRae, James I.; Barrett, Michael P.; McConville, Malcolm J.

2016-01-01

Malaria parasites (Plasmodium spp.) encounter markedly different (nutritional) environments during their complex life cycles in the mosquito and human hosts. Adaptation to these different host niches is associated with a dramatic rewiring of metabolism, from a highly glycolytic metabolism in the asexual blood stages to increased dependence on tricarboxylic acid (TCA) metabolism in mosquito stages. Here we have used stable isotope labelling, targeted metabolomics and reverse genetics to map stage-specific changes in Plasmodium berghei carbon metabolism and determine the functional significance of these changes on parasite survival in the blood and mosquito stages. We show that glutamine serves as the predominant input into TCA metabolism in both asexual and sexual blood stages and is important for complete male gametogenesis. Glutamine catabolism, as well as key reactions in intermediary metabolism and CoA synthesis are also essential for ookinete to oocyst transition in the mosquito. These data extend our knowledge of Plasmodium metabolism and point towards possible targets for transmission-blocking intervention strategies. Furthermore, they highlight significant metabolic differences between Plasmodium species which are not easily anticipated based on genomics or transcriptomics studies and underline the importance of integration of metabolomics data with other platforms in order to better inform drug discovery and design. PMID:28027318

Spatial Epidemiology of Plasmodium vivax, Afghanistan

PubMed Central

Leslie, Toby; Kolaczinski, Kate; Mohsen, Engineer; Mehboob, Najeebullah; Saleheen, Sarah; Khudonazarov, Juma; Freeman, Tim; Clements, Archie; Rowland, Mark; Kolaczinski, Jan

2006-01-01

Plasmodium vivax is endemic to many areas of Afghanistan. Geographic analysis helped highlight areas of malaria risk and clarified ecologic risk factors for transmission. Remote sensing enabled development of a risk map, thereby providing a valuable tool to help guide malaria control strategies. PMID:17176583

Unusual Transmission of Plasmodium falciparum, Bordeaux, France, 2009

PubMed Central

Vareil, Marc-Olivier; Tandonnet, Olivier; Chemoul, Audrey; Bogreau, Hervé; Saint-Léger, Mélanie; Micheau, Maguy; Millet, Pascal; Koeck, Jean-Louis; Boyer, Alexandre; Rogier, Christophe

2011-01-01

Plasmodium falciparum malaria is usually transmitted by mosquitoes. We report 2 cases in France transmitted by other modes: occupational blood exposure and blood transfusion. Even where malaria is not endemic, it should be considered as a cause of unexplained acute fever. PMID:21291597

Genetic evidence for contribution of human dispersal to the genetic diversity of EBA-175 in Plasmodium falciparum.

PubMed

Yasukochi, Yoshiki; Naka, Izumi; Patarapotikul, Jintana; Hananantachai, Hathairad; Ohashi, Jun

2015-08-01

The 175-kDa erythrocyte binding antigen (EBA-175) of Plasmodium falciparum plays a crucial role in merozoite invasion into human erythrocytes. EBA-175 is believed to have been under diversifying selection; however, there have been no studies investigating the effect of dispersal of humans out of Africa on the genetic variation of EBA-175 in P. falciparum. The PCR-direct sequencing was performed for a part of the eba-175 gene (regions II and III) using DNA samples obtained from Thai patients infected with P. falciparum. The divergence times for the P. falciparum eba-175 alleles were estimated assuming that P. falciparum/Plasmodium reichenowi divergence occurred 6 million years ago (MYA). To examine the possibility of diversifying selection, nonsynonymous and synonymous substitution rates for Plasmodium species were also estimated. A total of 32 eba-175 alleles were identified from 131 Thai P. falciparum isolates. Their estimated divergence time was 0.13-0.14 MYA, before the exodus of humans from Africa. A phylogenetic tree for a large sequence dataset of P. falciparum eba-175 alleles from across the world showed the presence of a basal Asian-specific cluster for all P. falciparum sequences. A markedly more nonsynonymous substitutions than synonymous substitutions in region II in P. falciparum was also detected, but not within Plasmodium species parasitizing African apes, suggesting that diversifying selection has acted specifically on P. falciparum eba-175. Plasmodium falciparum eba-175 genetic diversity appeared to increase following the exodus of Asian ancestors from Africa. Diversifying selection may have played an important role in the diversification of eba-175 allelic lineages. The present results suggest that the dispersals of humans out of Africa influenced significantly the molecular evolution of P. falciparum EBA-175.

Antiplasmodial activity of two medicinal plants against clinical isolates of Plasmodium falciparum and Plasmodium berghei infected mice.

PubMed

Attemene, Serge David Dago; Beourou, Sylvain; Tuo, Karim; Gnondjui, Albert Alloh; Konate, Abibatou; Toure, Andre Offianan; Kati-Coulibaly, Seraphin; Djaman, Joseph Alico

2018-03-01

Malaria is an infectious and deadly parasitic disease, associated with fever, anaemia and other ailments. Unfortunately the upsurge of plasmodium multidrug resistant constrained researchers to look for new effective drugs. Medicinal plants seem to be an unquenchable source of bioactive principles in the treatment of various diseases. The aim of this study was to assess the antiplasmodial activity of two Ivorian medicinal plants. The in vitro activity was evaluated against clinical isolates and Plasmodium falciparum K1 multidrug resistant strain using the fluorescence based SYBR green I assay. The in vivo bioassay was carried out using the classical 4 day suppressive and curative tests on Plasmodium berghei infected mice. Results showed that the in vitro bioassay of both plant extracts were found to exhibit a promising and moderate antiparasitic effects on clinical isolates (5 µg/mL < IC 50  < 15 µg/mL) and Plasmodium falciparum multidrug resistant K1 strain (15 µg/mL < IC 50  < 50 µg/mL). Furthermore, the in vivo antiplasmodial screening of both extracts showed a significant decrease in parasitemia, which was dose-dependent. Body temperature in mice treated with both extracts at experimental doses increased, compared to the negative control group and was dose-dependent. As for mice body weight a significant decrease ( p  < 0.001) was noticed in the negative control group compared to tested groups of animals. The hydroethanolic stem bark extract of Anthocleista djalonensis A Chev and leaves extract of Ziziphus mauritiana Lam exhibited anti-malarial activities. Therefore, the bioactive compounds of both plant extracts need to be investigated.

Platelets activate a pathogenic response to blood-stage Plasmodium infection but not a protective immune response.

PubMed

Gramaglia, Irene; Velez, Joyce; Combes, Valery; Grau, Georges E R; Wree, Melanie; van der Heyde, Henri C

2017-03-23

Clinical studies indicate that thrombocytopenia correlates with the development of severe falciparum malaria, suggesting that platelets either contribute to control of parasite replication, possibly as innate parasite killer cells or function in eliciting pathogenesis. Removal of platelets by anti-CD41 mAb treatment, platelet inhibition by aspirin, and adoptive transfer of wild-type (WT) platelets to CD40-KO mice, which do not control parasite replication, resulted in similar parasitemia compared with control mice. Human platelets at a physiologic ratio of 1 platelet to 9 red blood cells (RBCs) did not inhibit the in vitro development or replication of blood-stage Plasmodium falciparum The percentage of Plasmodium -infected (iRBCs) with bound platelets during the ascending parasitemia in Plasmodium chabaudi - and Plasmodium berghei -infected mice and the 48-hour in vitro cycle of P falciparum was <10%. P chabaudi and P berghei iRBCs with apoptotic parasites (TdT + ) exhibited minimal platelet binding (<5%), which was similar to nonapoptotic iRBCs. These findings collectively indicate platelets do not kill bloodstage Plasmodium at physiologically relevant effector-to-target ratios. P chabaudi primary and secondary parasitemia was similar in mice depleted of platelets by mAb-injection just before infection, indicating that activation of the protective immune response does not require platelets. In contrast to the lack of an effect on parasite replication, adoptive transfer of WT platelets to CD40-KO mice, which are resistant to experimental cerebral malaria, partially restored experimental cerebral malaria mortality and symptoms in CD40-KO recipients, indicating platelets elicit pathogenesis and platelet CD40 is a key molecule. © 2017 by The American Society of Hematology.

Memory T cells maintain protracted protection against malaria.

PubMed

Krzych, Urszula; Zarling, Stasya; Pichugin, Alexander

2014-10-01

Immunologic memory is one of the cardinal features of antigen-specific immune responses, and the persistence of memory cells contributes to prophylactic immunizations against infectious agents. Adequately maintained memory T and B cell pools assure a fast, effective and specific response against re-infections. However, many aspects of immunologic memory are still poorly understood, particularly immunologic memory inducible by parasites, for example, Plasmodium spp., the causative agents of malaria. For example, memory responses to Plasmodium antigens amongst residents of malaria endemic areas appear to be either inadequately developed or maintained, because persons who survive episodes of childhood malaria remain vulnerable to intermittent malaria infections. By contrast, multiple exposures of humans and laboratory rodents to radiation-attenuated Plasmodium sporozoites (γ-spz) induce sterile and long-lasting protection against experimental sporozoite challenge. Multifactorial immune mechanisms maintain this protracted and sterile protection. While the presence of memory CD4 T cell subsets has been associated with lasting protection in humans exposed to multiple bites from Anopheles mosquitoes infected with attenuated Plasmodium falciparum, memory CD8 T cells maintain protection induced with Plasmodium yoelii and Plasmodium berghei γ-spz in murine models. In this review, we discuss our observations that show memory CD8 T cells specific for antigens expressed by P. berghei liver stage parasites as an indispensable component for the maintenance of protracted protective immunity against experimental malaria infection; moreover, the provision of an Ag-depot assures a quick recall of memory T cells as IFN-γ-producing effector CD8 T cells and IL-4- producing CD4 T cells that collaborate with B cells for an effective antibody response. Published by Elsevier B.V.

Mitochondrial DNA from the eradicated European Plasmodium vivax and P. falciparum from 70-year-old slides from the Ebro Delta in Spain

PubMed Central

Gelabert, Pere; Sandoval-Velasco, Marcela; Olalde, Iñigo; Fregel, Rosa; Rieux, Adrien; Escosa, Raül; Aranda, Carles; Paaijmans, Krijn; Mueller, Ivo; Gilbert, M. Thomas P.; Lalueza-Fox, Carles

2016-01-01

Phylogenetic analysis of Plasmodium parasites has indicated that their modern-day distribution is a result of a series of human-mediated dispersals involving transport between Africa, Europe, America, and Asia. A major outstanding question is the phylogenetic affinity of the malaria causing parasites Plasmodium vivax and falciparum in historic southern Europe—where it was endemic until the mid-20th century, after which it was eradicated across the region. Resolving the identity of these parasites will be critical for answering several hypotheses on the malaria dispersal. Recently, a set of slides with blood stains of malaria-affected people from the Ebro Delta (Spain), dated between 1942 and 1944, have been found in a local medical collection. We extracted DNA from three slides, two of them stained with Giemsa (on which Plasmodium parasites could still be seen under the microscope) and another one consisting of dried blood spots. We generated the data using Illumina sequencing after using several strategies aimed at increasing the Plasmodium DNA yield: depletion of the human genomic (g)DNA content through hybridization with human gDNA baits, and capture-enrichment using gDNA derived from P. falciparum. Plasmodium mitochondrial genome sequences were subsequently reconstructed from the resulting data. Phylogenetic analysis of the eradicated European P. vivax mtDNA genome indicates that the European isolate is closely related to the most common present-day American haplotype and likely entered the American continent post-Columbian contact. Furthermore, the European P. falciparum mtDNA indicates a link with current Indian strains that is in agreement with historical accounts. PMID:27671660

Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands

PubMed Central

2013-01-01

Background Temotu Province, Solomon Islands is progressing toward malaria elimination. A baseline survey conducted in 2008 showed that most Plasmodium infections in the province were of low parasite density and asymptomatic infections. To better understand mechanisms underlying these malaria transmission characteristics genetic diversity and relationships among Plasmodium falciparum and Plasmodium vivax populations in the province were examined. Methods Forty-five P. falciparum and 67 P. vivax samples collected in the 2008 baseline survey were successfully genotyped using eight P. falciparum and seven P. vivax microsatellite markers. Genetic diversity, relationships and distribution of both P. falciparum and P. vivax populations were analysed. Results Plasmodium falciparum population exhibited low diversity with 19 haplotypes identified and had closely related clusters indicating clonal expansion. Interestingly, a dominant haplotype was significantly associated with fever and high parasite density. In contrast, the P. vivax population was highly diverse with 58 haplotypes identified that were not closely related. Parasite populations between different islands in the province showed low genetic differentiation. Conclusion The low diversity and clonal population of P. falciparum population may partially account for clinical immunity developed against illness. However, it is possible that importation of a new P. falciparum strain was the major cause of illness. High diversity in P. vivax population and low relatedness between strains suggested clinical immunity to P. vivax may be maintained by different mechanisms. The genetic diversity, population structure and distribution of strains indicate that transmission of P. falciparum was low, but that of P. vivax was still high in 2008. These data will be useful for assessing changes in malaria transmission resulting from interventions. PMID:24261646

Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the 'Sinton and Mulligan' Stipplings in the Cytoplasm of Monkey and Human Erythrocytes.

PubMed

Lucky, Amuza Byaruhanga; Sakaguchi, Miako; Katakai, Yuko; Kawai, Satoru; Yahata, Kazuhide; Templeton, Thomas J; Kaneko, Osamu

2016-01-01

The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as 'Sinton and Mulligan' stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum.

A three-genome phylogeny of malaria parasites (Plasmodium and closely related genera): evolution of life-history traits and host switches.

PubMed

Martinsen, Ellen S; Perkins, Susan L; Schall, Jos J

2008-04-01

Phylogenetic analysis of genomic data allows insights into the evolutionary history of pathogens, especially the events leading to host switching and diversification, as well as alterations of the life cycle (life-history traits). Hundreds, perhaps thousands, of malaria parasite species exploit squamate reptiles, birds, and mammals as vertebrate hosts as well as many genera of dipteran vectors, but the evolutionary and ecological events that led to this diversification and success remain unresolved. For a century, systematic parasitologists classified malaria parasites into genera based on morphology, life cycle, and vertebrate and insect host taxa. Molecular systematic studies based on single genes challenged the phylogenetic significance of these characters, but several significant nodes were not well supported. We recovered the first well resolved large phylogeny of Plasmodium and related haemosporidian parasites using sequence data for four genes from the parasites' three genomes by combining all data, correcting for variable rates of substitution by gene and site, and using both Bayesian and maximum parsimony analyses. Major clades are associated with vector shifts into different dipteran families, with other characters used in traditional parasitological studies, such as morphology and life-history traits, having variable phylogenetic significance. The common parasites of birds now placed into the genus Haemoproteus are found in two divergent clades, and the genus Plasmodium is paraphyletic with respect to Hepatocystis, a group of species with very different life history and morphology. The Plasmodium of mammal hosts form a well supported clade (including Plasmodium falciparum, the most important human malaria parasite), and this clade is associated with specialization to Anopheles mosquito vectors. The Plasmodium of birds and squamate reptiles all fall within a single clade, with evidence for repeated switching between birds and squamate hosts.

Mitochondrial DNA from the eradicated European Plasmodium vivax and P. falciparum from 70-year-old slides from the Ebro Delta in Spain.

PubMed

Gelabert, Pere; Sandoval-Velasco, Marcela; Olalde, Iñigo; Fregel, Rosa; Rieux, Adrien; Escosa, Raül; Aranda, Carles; Paaijmans, Krijn; Mueller, Ivo; Gilbert, M Thomas P; Lalueza-Fox, Carles

2016-10-11

Phylogenetic analysis of Plasmodium parasites has indicated that their modern-day distribution is a result of a series of human-mediated dispersals involving transport between Africa, Europe, America, and Asia. A major outstanding question is the phylogenetic affinity of the malaria causing parasites Plasmodium vivax and falciparum in historic southern Europe-where it was endemic until the mid-20th century, after which it was eradicated across the region. Resolving the identity of these parasites will be critical for answering several hypotheses on the malaria dispersal. Recently, a set of slides with blood stains of malaria-affected people from the Ebro Delta (Spain), dated between 1942 and 1944, have been found in a local medical collection. We extracted DNA from three slides, two of them stained with Giemsa (on which Plasmodium parasites could still be seen under the microscope) and another one consisting of dried blood spots. We generated the data using Illumina sequencing after using several strategies aimed at increasing the Plasmodium DNA yield: depletion of the human genomic (g)DNA content through hybridization with human gDNA baits, and capture-enrichment using gDNA derived from P. falciparum Plasmodium mitochondrial genome sequences were subsequently reconstructed from the resulting data. Phylogenetic analysis of the eradicated European P. vivax mtDNA genome indicates that the European isolate is closely related to the most common present-day American haplotype and likely entered the American continent post-Columbian contact. Furthermore, the European P. falciparum mtDNA indicates a link with current Indian strains that is in agreement with historical accounts.

Human Infections with Plasmodium knowlesi, the Philippines

PubMed Central

Espino, Fe; Curameng, Peter; Espina, Ronald; Bell, David; Chiodini, Peter; Nolder, Debbie; Sutherland, Colin; Lee, Kim-Sung; Singh, Balbir

2008-01-01

Five human cases of infection with the simian malaria parasite Plasmodium knowlesi from Palawan, the Philippines, were confirmed by nested PCR. This study suggests that this zoonotic infection is found across a relatively wide area in Palawan and documents autochthonous cases in the country. PMID:18439369

Molecular mechanisms mediating immune priming in Anopheles gambiae mosquitos

USDA-ARS?s Scientific Manuscript database

The Anopheles gambiae immune priming response is triggered when Plasmodium ookinetes invade the mosquito midgut and the microbiota comes in direct contact with injured cells. This is a long-lasting response that confers the challenged mosquito enhanced ability to control subsequent Plasmodium infect...

Reduced erythrocyte susceptibility and increased host clearance of young parasites slows Plasmodium growth in a murine model of severe malaria

NASA Astrophysics Data System (ADS)

Khoury, David S.; Cromer, Deborah; Best, Shannon E.; James, Kylie R.; Sebina, Ismail; Haque, Ashraful; Davenport, Miles P.

2015-05-01

The best correlate of malaria severity in human Plasmodium falciparum (Pf) infection is the total parasite load. Pf-infected humans could control parasite loads by two mechanisms, either decreasing parasite multiplication, or increasing parasite clearance. However, few studies have directly measured these two mechanisms in vivo. Here, we have directly quantified host clearance of parasites during Plasmodium infection in mice. We transferred labelled red blood cells (RBCs) from Plasmodium infected donors into uninfected and infected recipients, and tracked the fate of donor parasites by frequent blood sampling. We then applied age-based mathematical models to characterise parasite clearance in the recipient mice. Our analyses revealed an increased clearance of parasites in infected animals, particularly parasites of a younger developmental stage. However, the major decrease in parasite multiplication in infected mice was not mediated by increased clearance alone, but was accompanied by a significant reduction in the susceptibility of RBCs to parasitisation.

Clues to evolution of the SERA multigene family in 18 Plasmodium species.

PubMed

Arisue, Nobuko; Kawai, Satoru; Hirai, Makoto; Palacpac, Nirianne M Q; Jia, Mozhi; Kaneko, Akira; Tanabe, Kazuyuki; Horii, Toshihiro

2011-03-15

SERA gene sequences were newly determined from 11 primate Plasmodium species including two human parasites, P. ovale and P. malariae, and the evolutionary history of SERA genes was analyzed together with 7 known species. All have one each of Group I to III cysteine-type SERA genes and varying number of Group IV serine-type SERA genes in tandem cluster. Notably, Group IV SERA genes were ascertained in all mammalian parasite lineages; and in two primate parasite lineages gene events such as duplication, truncation, fragmentation and gene loss occurred at high frequency in a manner that mimics the birth-and-death evolution model. Transcription profile of individual SERA genes varied greatly among rodent and monkey parasites. Results support the lineage-specific evolution of the Plasmodium SERA gene family. These findings provide further impetus for studies that could clarify/provide proof-of-concept that duplications of SERA genes were associated with the parasites' expansion of host range and the evolutionary conundrums of multigene families in Plasmodium.

Targeting Plasmodium PI(4)K to eliminate malaria.

PubMed

McNamara, Case W; Lee, Marcus Cs; Lim, Chek Shik; Lim, Siau Hoi; Roland, Jason; Simon, Oliver; Yeung, Bryan Ks; Chatterjee, Arnab K; McCormack, Susan L; Manary, Micah J; Zeeman, Anne-Marie; Dechering, Koen J; Kumar, Tr Santha; Henrich, Philipp P; Gagaring, Kerstin; Ibanez, Maureen; Kato, Nobutaka; Kuhen, Kelli L; Fischli, Christoph; Nagle, Advait; Rottmann, Matthias; Plouffe, David M; Bursulaya, Badry; Meister, Stephan; Rameh, Lucia; Trappe, Joerg; Haasen, Dorothea; Timmerman, Martijn; Sauerwein, Robert W; Suwanarusk, Rossarin; Russell, Bruce; Renia, Laurent; Nosten, Francois; Tully, David C; Kocken, Clemens Hm; Glynne, Richard J; Bodenreider, Christophe; Fidock, David A; Diagana, Thierry T; Winzeler, Elizabeth A

2013-12-12

Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria.

Global Epidemiology of Plasmodium vivax

PubMed Central

Howes, Rosalind E.; Battle, Katherine E.; Mendis, Kamini N.; Smith, David L.; Cibulskis, Richard E.; Baird, J. Kevin; Hay, Simon I.

2016-01-01

Plasmodium vivax is the most widespread human malaria, putting 2.5 billion people at risk of infection. Its unique biological and epidemiological characteristics pose challenges to control strategies that have been principally targeted against Plasmodium falciparum. Unlike P. falciparum, P. vivax infections have typically low blood-stage parasitemia with gametocytes emerging before illness manifests, and dormant liver stages causing relapses. These traits affect both its geographic distribution and transmission patterns. Asymptomatic infections, high-risk groups, and resulting case burdens are described in this review. Despite relatively low prevalence measurements and parasitemia levels, along with high proportions of asymptomatic cases, this parasite is not benign. Plasmodium vivax can be associated with severe and even fatal illness. Spreading resistance to chloroquine against the acute attack, and the operational inadequacy of primaquine against the multiple attacks of relapse, exacerbates the risk of poor outcomes among the tens of millions suffering from infection each year. Without strategies accounting for these P. vivax-specific characteristics, progress toward elimination of endemic malaria transmission will be substantially impeded. PMID:27402513

Can a single "powerless" mitochondrion in the malaria parasite contribute to parasite programmed cell death in the asexual stages?

PubMed

Ch'ng, Jun-Hong; Yeo, Su-Ping; Shyong-Wei Tan, Kevin

2013-05-01

The protozoan pathogens responsible for malaria are from the Plasmodium genus, with Plasmodium falciparum and Plasmodium vivax accounting for almost all clinical infections. With recent estimates of mortality exceeding 800,000 annually, malaria continues to take a terrible toll on lives and the early promises of medicine to eradicate the disease have yet to approach realization, in part due to the spread of drug resistant parasites. Recent reports of artemisinin-resistance have prompted renewed efforts to identify novel therapeutic options, and one such pathway being considered for antimalarial exploit is the parasite's programmed cell death (PCD) pathway. In this mini-review, we will discuss the roles of the plasmodium mitochondria in cell death and as a target of antimalarial compounds, taking into account recent data suggesting that PCD pathways involving the mitochondria may be attractive antimalarial targets. Copyright © 2012 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

A microscale human liver platform that supports the hepatic stages of Plasmodium falciparum and vivax

PubMed Central

March, Sandra; Ng, Shengyong; Velmurugan, Soundarapandian; Galstian, Ani; Shan, Jing; Logan, David; Carpenter, Anne; Thomas, David; Lee Sim, B. Kim; Mota, Maria M.; Hoffman, Stephen L.; Bhatia, Sangeeta N.

2013-01-01

SUMMARY The Plasmodium liver stage is an attractive target for the development of anti-malarial drugs and vaccines, as it provides an opportunity to interrupt the life cycle of the parasite at a critical early stage. However, targeting the liver stage has been difficult. Undoubtedly, a major barrier has been the lack of robust, reliable and reproducible in vitro liver stage cultures. Here, we establish the liver stages for both Plasmodium falciparum and Plasmodium vivax in a microscale human liver platform composed of cryopreserved, micropatterned human primary hepatocytes surrounded by supportive stromal cells. Using this system, we have successfully recapitulated the full liver stage of P. falciparum including the release of infected merozoites and infection of overlaid erythrocytes, and also the establishment of small forms in late liver stages of P. vivax. Finally, we validate the potential of this platform as a tool for medium-throughput anti-malarial drug screening and vaccine development. PMID:23870318

Host scavenger receptor SR-BI plays a dual role in the establishment of malaria parasite liver infection.

PubMed

Rodrigues, Cristina D; Hannus, Michael; Prudêncio, Miguel; Martin, Cécilie; Gonçalves, Lígia A; Portugal, Sílvia; Epiphanio, Sabrina; Akinc, Akin; Hadwiger, Philipp; Jahn-Hofmann, Kerstin; Röhl, Ingo; van Gemert, Geert-Jan; Franetich, Jean-François; Luty, Adrian J F; Sauerwein, Robert; Mazier, Dominique; Koteliansky, Victor; Vornlocher, Hans-Peter; Echeverri, Christophe J; Mota, Maria M

2008-09-11

An obligatory step of malaria parasite infection is Plasmodium sporozoite invasion of host hepatocytes, and host lipoprotein clearance pathways have been linked to Plasmodium liver infection. By using RNA interference to screen lipoprotein-related host factors, we show here that the class B, type I scavenger receptor (SR-BI) is the strongest regulator of Plasmodium infection among these factors. Inhibition of SR-BI function reduced P. berghei infection in Huh7 cells, and overexpression of SR-BI led to increased infection. In vivo silencing of liver SR-BI expression in mice and inhibition of SR-BI activity in human primary hepatocytes reduced infection by P. berghei and by P. falciparum, respectively. Heterozygous SR-BI(+/-) mice displayed reduced P. berghei infection rates correlating with liver SR-BI expression levels. Additional analyses revealed that SR-BI plays a dual role in Plasmodium infection, affecting both sporozoite invasion and intracellular parasite development, and may therefore constitute a good target for malaria prophylaxis.

In Vivo and In Vitro Characterization of a Plasmodium Liver Stage-Specific Promoter

PubMed Central

Horstmann, Sebastian; Annoura, Takeshi; del Portillo, Hernando A.; Khan, Shahid M.; Heussler, Volker T.

2015-01-01

Little is known about stage-specific gene regulation in Plasmodium parasites, in particular the liver stage of development. We have previously described in the Plasmodium berghei rodent model, a liver stage-specific (lisp2) gene promoter region, in vitro. Using a dual luminescence system, we now confirm the stage specificity of this promoter region also in vivo. Furthermore, by substitution and deletion analyses we have extended our in vitro characterization of important elements within the promoter region. Importantly, the dual luminescence system allows analyzing promoter constructs avoiding mouse-consuming cloning procedures of transgenic parasites. This makes extensive mutation and deletion studies a reasonable approach also in the malaria mouse model. Stage-specific expression constructs and parasite lines are extremely valuable tools for research on Plasmodium liver stage biology. Such reporter lines offer a promising opportunity for assessment of liver stage drugs, characterization of genetically attenuated parasites and liver stage-specific vaccines both in vivo and in vitro, and may be key for the generation of inducible systems. PMID:25874388

A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium

PubMed Central

Slavic, Ksenija; Krishna, Sanjeev; Lahree, Aparajita; Bouyer, Guillaume; Hanson, Kirsten K.; Vera, Iset; Pittman, Jon K.; Staines, Henry M.; Mota, Maria M.

2016-01-01

Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km∼14.7 μM), and selective for Fe2+ over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit−) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit− parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host. PMID:26786069

A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium.

PubMed

Slavic, Ksenija; Krishna, Sanjeev; Lahree, Aparajita; Bouyer, Guillaume; Hanson, Kirsten K; Vera, Iset; Pittman, Jon K; Staines, Henry M; Mota, Maria M

2016-01-20

Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km ∼ 14.7 μM), and selective for Fe(2+) over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit(-)) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit(-) parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host.

Targeting Plasmodium PI(4)K to eliminate malaria

NASA Astrophysics Data System (ADS)

McNamara, Case W.; Lee, Marcus C. S.; Lim, Chek Shik; Lim, Siau Hoi; Roland, Jason; Nagle, Advait; Simon, Oliver; Yeung, Bryan K. S.; Chatterjee, Arnab K.; McCormack, Susan L.; Manary, Micah J.; Zeeman, Anne-Marie; Dechering, Koen J.; Kumar, T. R. Santha; Henrich, Philipp P.; Gagaring, Kerstin; Ibanez, Maureen; Kato, Nobutaka; Kuhen, Kelli L.; Fischli, Christoph; Rottmann, Matthias; Plouffe, David M.; Bursulaya, Badry; Meister, Stephan; Rameh, Lucia; Trappe, Joerg; Haasen, Dorothea; Timmerman, Martijn; Sauerwein, Robert W.; Suwanarusk, Rossarin; Russell, Bruce; Renia, Laurent; Nosten, Francois; Tully, David C.; Kocken, Clemens H. M.; Glynne, Richard J.; Bodenreider, Christophe; Fidock, David A.; Diagana, Thierry T.; Winzeler, Elizabeth A.

2013-12-01

Achieving the goal of malaria elimination will depend on targeting Plasmodium pathways essential across all life stages. Here we identify a lipid kinase, phosphatidylinositol-4-OH kinase (PI(4)K), as the target of imidazopyrazines, a new antimalarial compound class that inhibits the intracellular development of multiple Plasmodium species at each stage of infection in the vertebrate host. Imidazopyrazines demonstrate potent preventive, therapeutic, and transmission-blocking activity in rodent malaria models, are active against blood-stage field isolates of the major human pathogens P. falciparum and P. vivax, and inhibit liver-stage hypnozoites in the simian parasite P. cynomolgi. We show that imidazopyrazines exert their effect through inhibitory interaction with the ATP-binding pocket of PI(4)K, altering the intracellular distribution of phosphatidylinositol-4-phosphate. Collectively, our data define PI(4)K as a key Plasmodium vulnerability, opening up new avenues of target-based discovery to identify drugs with an ideal activity profile for the prevention, treatment and elimination of malaria.

Docking, synthesis and antimalarial activity of novel 4-anilinoquinoline derivatives.

PubMed

Vijayaraghavan, Shilpa; Mahajan, Supriya

2017-04-15

A series of 4-anilinoquinoline triazine derivatives were designed, synthesized and screened for in vivo antimalarial activity against a chloroquine-sensitive strain of Plasmodium berghei. The compounds were further subjected to in vitro antimalarial activity against chloroquine-resistant W2 strain of Plasmodium falciparum and β-haematin inhibition studies. All the compounds exhibited in vivo antimalarial activity better than that shown by the standard drug, chloroquine. Twelve out of fifteen compounds showed better inhibition than that of chloroquine against chloroquine-resistant W2 strain of Plasmodium falciparum. Ten compounds showed β-haematin inhibition, better than that of chloroquine, with IC 50 values in the range of 18-25µM. One compound, 3k, was found to be better than artemisinin against W2 strain of Plasmodium falciparum and also displayed the best β-haematin inhibitory activity, thereby becoming eligible to be explored as a potential lead for antimalarial chemotherapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environment-dependent morphology in plasmodium of true slime mold Physarum polycephalum and a network growth model.

PubMed

Takamatsu, Atsuko; Takaba, Eri; Takizawa, Ginjiro

2009-01-07

Branching network growth patterns, depending on environmental conditions, in plasmodium of true slime mold Physarum polycephalum were investigated. Surprisingly, the patterns resemble those in bacterial colonies even though the biological mechanisms differ greatly. Bacterial colonies are collectives of microorganisms in which individual organisms have motility and interact through nutritious and chemical fields. In contrast, the plasmodium is a giant amoeba-like multinucleated unicellular organism that forms a network of tubular structures through which protoplasm streams. The cell motility of the plasmodium is generated by oscillation phenomena observed in the partial bodies, which interact through the tubular structures. First, we analyze characteristics of the morphology quantitatively, then we abstract local rules governing the growing process to construct a simple network growth model. This model is independent of specific systems, in which only two rules are applied. Finally, we discuss the mechanism of commonly observed biological pattern formations through comparison with the system of bacterial colonies.

"Plasmo2D": an ancillary proteomic tool to aid identification of proteins from Plasmodium falciparum.

PubMed

Khachane, Amit; Kumar, Ranjit; Jain, Sanyam; Jain, Samta; Banumathy, Gowrishankar; Singh, Varsha; Nagpal, Saurabh; Tatu, Utpal

2005-01-01

Bioinformatics tools to aid gene and protein sequence analysis have become an integral part of biology in the post-genomic era. Release of the Plasmodium falciparum genome sequence has allowed biologists to define the gene and the predicted protein content as well as their sequences in the parasite. Using pI and molecular weight as characteristics unique to each protein, we have developed a bioinformatics tool to aid identification of proteins from Plasmodium falciparum. The tool makes use of a Virtual 2-DE generated by plotting all of the proteins from the Plasmodium database on a pI versus molecular weight scale. Proteins are identified by comparing the position of migration of desired protein spots from an experimental 2-DE and that on a virtual 2-DE. The procedure has been automated in the form of user-friendly software called "Plasmo2D". The tool can be downloaded from http://144.16.89.25/Plasmo2D.zip.

Transmission-blocking interventions eliminate malaria from laboratory populations

PubMed Central

Blagborough, A. M.; Churcher, T. S.; Upton, L. M.; Ghani, A. C.; Gething, P. W.; Sinden, R. E.

2013-01-01

Transmission-blocking interventions aim to reduce the prevalence of infection in endemic communities by targeting Plasmodium within the insect host. Although many studies have reported the successful reduction of infection in the mosquito vector, direct evidence that there is an onward reduction in infection in the vertebrate host is lacking. Here we report the first experiments using a population, transmission-based study of Plasmodium berghei in Anopheles stephensi to assess the impact of a transmission-blocking drug upon both insect and host populations over multiple transmission cycles. We demonstrate that the selected transmission-blocking intervention, which inhibits transmission from vertebrate to insect by only 32%, reduces the basic reproduction number of the parasite by 20%, and in our model system can eliminate Plasmodium from mosquito and mouse populations at low transmission intensities. These findings clearly demonstrate that use of transmission-blocking interventions alone can eliminate Plasmodium from a vertebrate population, and have significant implications for the future design and implementation of transmission-blocking interventions within the field. PMID:23652000

Targeting Angiotensin II Type-1 Receptor (AT1R) Inhibits the Harmful Phenotype of Plasmodium-Specific CD8+ T Cells during Blood-Stage Malaria.

PubMed

Silva-Filho, João L; Caruso-Neves, Celso; Pinheiro, Ana A S

2017-01-01

CD8 + T-cell response is critical in the pathogenesis of cerebral malaria during blood-stage. Our group and other have been shown that angiotensin II (Ang II) and its receptor AT 1 (AT 1 R), a key effector axis of renin-angiotensin system (RAS), have immune regulatory effects on T cells. Previously, we showed that inhibition of AT 1 R signaling protects mice against the lethal disease induced by Plasmodium berghei ANKA infection However, most of the Ang II/AT 1 R actions were characterized by using only pharmacological approaches, the effects of which may not always be due to a specific receptor blockade. In addition, the mechanisms of action of the AT 1 R in inducing the pathogenic activity of Plasmodium -specific CD8 + T cells during blood-stage were not determined. Here, we examined how angiotensin II/AT 1 R axis promotes the harmful response of Plasmodium -specific CD8 + T-cell during blood-stage by using genetic and pharmacological approaches. We evaluated the response of wild-type (WT) and AT 1 R -/- Plasmodium -specific CD8 + T cells in mice infected with a transgenic PbA lineage expressing ovalbumin; and in parallel infected mice receiving WT Plasmodium -specific CD8 + T cells were treated with losartan (AT 1 R antagonist) or captopril (ACE inhibitor). Both, AT 1 R -/- OT-I cells and WT OT-I cells from losartan- or captopril-treated mice showed lower expansion, reduced IL-2 production and IL-2Rα expression, lower activation (lower expression of CD69, CD44 and CD160) and lower exhaustion profiles. AT 1 R -/- OT-I cells also exhibit lower expression of the integrin LFA-1 and the chemokine receptors CCR5 and CXCR3, known to play a key role in the development of cerebral malaria. Moreover, AT 1 R -/- OT-I cells produce lower amounts of IFN-γ and TNF-α and show lower degranulation upon restimulation. In conclusion, our results show the pivotal mechanisms of AT 1 R-induced harmful phenotype of Plasmodium -specific CD8 + T cells during blood-stage malaria.

Backward bifurcation and optimal control of Plasmodium Knowlesi malaria

NASA Astrophysics Data System (ADS)

Abdullahi, Mohammed Baba; Hasan, Yahya Abu; Abdullah, Farah Aini

2014-07-01

A deterministic model for the transmission dynamics of Plasmodium Knowlesi malaria with direct transmission is developed. The model is analyzed using dynamical system techniques and it shows that the backward bifurcation occurs for some range of parameters. The model is extended to assess the impact of time dependent preventive (biological and chemical control) against the mosquitoes and vaccination for susceptible humans, while treatment for infected humans. The existence of optimal control is established analytically by the use of optimal control theory. Numerical simulations of the problem, suggest that applying the four control measure can effectively reduce if not eliminate the spread of Plasmodium Knowlesi in a community.

In vitro activity of wALADin benzimidazoles against different life cycle stages of Plasmodium parasites.

PubMed

Lentz, Christian S; Sattler, Julia M; Fendler, Martina; Gottwalt, Simon; Halls, Victoria S; Strassel, Silke; Arriens, Sandra; Hannam, Jeffrey S; Specht, Sabine; Famulok, Michael; Mueller, Ann-Kristin; Hoerauf, Achim; Pfarr, Kenneth M

2015-01-01

wALADin1 benzimidazoles are specific inhibitors of δ-aminolevulinic acid dehydratase from Wolbachia endobacteria of filarial nematodes. We report that wALADin1 and two derivatives killed blood stage Plasmodium falciparum in vitro (50% inhibitory concentrations, 39, 7.7, and 12.8 μM, respectively). One of these derivatives inhibited gliding motility of Plasmodium berghei ANKA infectious sporozoites with nanomolar affinity and blocked invasion into hepatocytes but did not affect intrahepatocytic replication. Hence, wALADin1 benzimidazoles are tools to study gliding motility and potential antiplasmodial drug candidates. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Therapeutic principles of primaquine against relapse of Plasmodium vivax malaria

NASA Astrophysics Data System (ADS)

Baird, J. K.

2018-03-01

Plasmodium vivax causes tens of millions of clinical attacks annually all across the malarious globe. Unlike the other major cause of human malaria, Plasmodium falciparum, P. vivax places dormant stages called hypnozoites into the human liver that later awaken and provoke multiple clinical attacks in the weeks, months, and few years following the infectious anopheline mosquito bite. The only available treatment to prevent those recurrent attacks is primaquine (hypnozoitocide), and it must be administered with the drugs applied to end the acute attack (blood schizontocides). This paper reviews the therapeutic principles of applying primaquine to achieve radical cure of acute vivax malaria.

Plasmodium falciparum Serine/Threonine Phosphoprotein Phosphatases (PPP): From Housekeeper to 'Holy Grail'

USDA-ARS?s Scientific Manuscript database

Availability of complete genome sequence for Plasmodium falciparum has been useful in drawing a comprehensive metabolic map of the parasite. Distinct and unique metabolic characteristics of the parasite may be exploited as potential targets for new antimalarial drug discovery research. Reversible ph...

Efficacy of integrated school based de-worming and prompt malaria treatment on helminths -Plasmodium falciparum co-infections: A 33 months follow up study.

PubMed

Midzi, Nicholas; Mtapuri-Zinyowera, Sekesai; Sangweme, Davison; Paul, Noah H; Makware, Godfrey; Mapingure, Munyaradzi P; Brouwer, Kimberly C; Mudzori, James; Hlerema, Gibson; Chadukura, Vivian; Mutapi, Francisca; Kumar, Nirbhay; Mduluza, Takafira

2011-06-22

The geographical congruency in distribution of helminths and Plasmodium falciparum makes polyparasitism a common phenomenon in Sub Saharan Africa. The devastating effects of helminths-Plasmodium co-infections on primary school health have raised global interest for integrated control. However little is known on the feasibility, timing and efficacy of integrated helminths-Plasmodium control strategies. A study was conducted in Zimbabwe to evaluate the efficacy of repeated combined school based antihelminthic and prompt malaria treatment. A cohort of primary schoolchildren (5-17 years) received combined Praziquantel, albendazole treatment at baseline, and again during 6, 12 and 33 months follow up surveys and sustained prompt malaria treatment. Sustained prompt malaria treatment was carried out throughout the study period. Children's infection status with helminths, Plasmodium and helminths-Plasmodium co-infections was determined by parasitological examinations at baseline and at each treatment point. The prevalence of S. haematobium, S. mansoni, STH, malaria, helminths-Plasmodium co-infections and helminths infection intensities before and after treatment were analysed. Longitudinal data showed that two rounds of combined Praziquantel and albendazole treatment for schistosomiasis and STHs at 6 monthly intervals and sustained prompt malaria treatment significantly reduced the overall prevalence of S. haematobium, S. mansoni, hookworms and P. falciparum infection in primary schoolchildren by 73.5%, 70.8%, 67.3% and 58.8% respectively (p < 0.001, p < 0.001, p < 0.001, p < 0.001 respectively). More importantly, the prevalence of STH + schistosomes, P. f + schistosomes, and P. f + STHs + schistosomes co-infections were reduced by 68.0%, 84.2%, and 90.7%, respectively. The absence of anti-helminthic treatment between the 12 mth and 33 mth follow-up surveys resulted in the sharp increase in STHs + schistosomes co-infection from 3.3% at 12 months follow up survey to 10.7%, slightly more than the baseline level (10.3%) while other co-infection combinations remained significantly low. The overall prevalence of heavy S. haematobium, S. mansoni and hookworms infection intensities were significantly reduced from: 17.9-22.4% to 2.6-5.1%, 1.6-3.3% to 0.0% and 0.0-0.7% to 0.0% respectively. Biannual Integrated school based antihelminthic and sustained prompt malaria treatment has a potential to reduce the burden of helminths-plasmodium co-infections in primary school children. In areas of stable malaria transmission, active case finding is recommended to track and treat asymptomatic malaria cases as these may sustain transmission in the community.

Efficacy of integrated school based de-worming and prompt malaria treatment on helminths -Plasmodium falciparum co-infections: A 33 months follow up study

PubMed Central

2011-01-01

Background The geographical congruency in distribution of helminths and Plasmodium falciparum makes polyparasitism a common phenomenon in Sub Saharan Africa. The devastating effects of helminths-Plasmodium co-infections on primary school health have raised global interest for integrated control. However little is known on the feasibility, timing and efficacy of integrated helminths-Plasmodium control strategies. A study was conducted in Zimbabwe to evaluate the efficacy of repeated combined school based antihelminthic and prompt malaria treatment. Methods A cohort of primary schoolchildren (5-17 years) received combined Praziquantel, albendazole treatment at baseline, and again during 6, 12 and 33 months follow up surveys and sustained prompt malaria treatment. Sustained prompt malaria treatment was carried out throughout the study period. Children's infection status with helminths, Plasmodium and helminths-Plasmodium co-infections was determined by parasitological examinations at baseline and at each treatment point. The prevalence of S. haematobium, S. mansoni, STH, malaria, helminths-Plasmodium co-infections and helminths infection intensities before and after treatment were analysed. Results Longitudinal data showed that two rounds of combined Praziquantel and albendazole treatment for schistosomiasis and STHs at 6 monthly intervals and sustained prompt malaria treatment significantly reduced the overall prevalence of S. haematobium, S. mansoni, hookworms and P. falciparum infection in primary schoolchildren by 73.5%, 70.8%, 67.3% and 58.8% respectively (p < 0.001, p < 0.001, p < 0.001, p < 0.001 respectively). More importantly, the prevalence of STH + schistosomes, P. f + schistosomes, and P. f + STHs + schistosomes co-infections were reduced by 68.0%, 84.2%, and 90.7%, respectively. The absence of anti-helminthic treatment between the 12 mth and 33 mth follow-up surveys resulted in the sharp increase in STHs + schistosomes co-infection from 3.3% at 12 months follow up survey to 10.7%, slightly more than the baseline level (10.3%) while other co-infection combinations remained significantly low. The overall prevalence of heavy S. haematobium, S. mansoni and hookworms infection intensities were significantly reduced from: 17.9-22.4% to 2.6-5.1%, 1.6-3.3% to 0.0% and 0.0-0.7% to 0.0% respectively. Conclusion Biannual Integrated school based antihelminthic and sustained prompt malaria treatment has a potential to reduce the burden of helminths-plasmodium co-infections in primary school children. In areas of stable malaria transmission, active case finding is recommended to track and treat asymptomatic malaria cases as these may sustain transmission in the community. PMID:21696629

Towards high-throughput molecular detection of Plasmodium: new approaches and molecular markers

PubMed Central

Steenkeste, Nicolas; Incardona, Sandra; Chy, Sophy; Duval, Linda; Ekala, Marie-Thérèse; Lim, Pharath; Hewitt, Sean; Sochantha, Tho; Socheat, Doung; Rogier, Christophe; Mercereau-Puijalon, Odile; Fandeur, Thierry; Ariey, Frédéric

2009-01-01

Background Several strategies are currently deployed in many countries in the tropics to strengthen malaria control toward malaria elimination. To measure the impact of any intervention, there is a need to detect malaria properly. Mostly, decisions still rely on microscopy diagnosis. But sensitive diagnosis tools enabling to deal with a large number of samples are needed. The molecular detection approach offers a much higher sensitivity, and the flexibility to be automated and upgraded. Methods Two new molecular methods were developed: dot18S, a Plasmodium-specific nested PCR based on the 18S rRNA gene followed by dot-blot detection of species by using species-specific probes and CYTB, a Plasmodium-specific nested PCR based on cytochrome b gene followed by species detection using SNP analysis. The results were compared to those obtained with microscopic examination and the "standard" 18S rRNA gene based nested PCR using species specific primers. 337 samples were diagnosed. Results Compared to the microscopy the three molecular methods were more sensitive, greatly increasing the estimated prevalence of Plasmodium infection, including P. malariae and P. ovale. A high rate of mixed infections was uncovered with about one third of the villagers infected with more than one malaria parasite species. Dot18S and CYTB sensitivity outranged the "standard" nested PCR method, CYTB being the most sensitive. As a consequence, compared to the "standard" nested PCR method for the detection of Plasmodium spp., the sensitivity of dot18S and CYTB was respectively 95.3% and 97.3%. Consistent detection of Plasmodium spp. by the three molecular methods was obtained for 83% of tested isolates. Contradictory results were mostly related to detection of Plasmodium malariae and Plasmodium ovale in mixed infections, due to an "all-or-none" detection effect at low-level parasitaemia. Conclusion A large reservoir of asymptomatic infections was uncovered using the molecular methods. Dot18S and CYTB, the new methods reported herein are highly sensitive, allow parasite DNA extraction as well as genus- and species-specific diagnosis of several hundreds of samples, and are amenable to high-throughput scaling up for larger sample sizes. Such methods provide novel information on malaria prevalence and epidemiology and are suited for active malaria detection. The usefulness of such sensitive malaria diagnosis tools, especially in low endemic areas where eradication plans are now on-going, is discussed in this paper. PMID:19402894

Asymptomatic and sub-microscopic malaria infection in Kayah State, eastern Myanmar.

PubMed

Zaw, Myo Thiha; Thant, Myo; Hlaing, Tin Maung; Aung, Naing Zin; Thu, Min; Phumchuea, Kanit; Phusri, Kanokwan; Saeseu, Teerawat; Yorsaeng, Ritthideach; Nguitragool, Wang; Felger, Ingrid; Kaewkungwal, Jaranit; Cui, Liwang; Sattabongkot, Jetsumon

2017-04-04

Myanmar has the heaviest burden of malaria in the Greater Mekong Sub-region. Asymptomatic Plasmodium spp. infections are common in this region and may represent an important reservoir of transmission that must be targeted for malaria elimination. A mass blood survey was conducted among 485 individuals from six villages in Kayah State, an area of endemic but low transmission malaria in eastern Myanmar. Malaria infection was screened by rapid diagnostic test (RDT), light microscopy and real-time polymerase chain reaction (PCR), and its association with demographic factors was explored. The prevalence of asymptomatic Plasmodium spp. infection was 2.3% (11/485) by real-time PCR. Plasmodium vivax accounted for 72.7% (8/11) and Plasmodium falciparum for 27.3% (3/11) of infections. Men were at greater risk of infection by Plasmodium spp. than women. Individuals who worked as farmers or wood and bamboo cutters had an increased risk of infection. A combination of RDT, light microscopy and PCR diagnostics were used to identify asymptomatic malaria infection, providing additional information on asymptomatic cases in addition to the routine statistics on symptomatic cases, so as to determine the true burden of disease in the area. Such information and risk factors can improve malaria risk stratification and guide decision-makers towards better design and delivery of targeted interventions in small villages, representative of Kayah State.

Simplified Pan-species Real-time PCR-based Detection of Plasmodium Spp. in Blood Smear.

PubMed

Hassanpour, Gholamreza; Mirhendi, Hossein; Mohebali, Mehdi; Raeisi, Ahmad; Zeraati, Hojjat; Keshavarz, Hossein

2016-01-01

We aimed to quicken and simplify the detection of Plasmodium in blood samples by developing and testing a pan- Plasmodium real-time PCR for accurate screening of individuals suspected of malaria. A single primer/probe set for pan-species Plasmodium -specific real time PCR targeting a conserved region of the small subunit 18S ribosomal DNA was designed and evaluated for rapid diagnosis and screening of malaria infections using dried blood smears. FTA cards were used for rapid and simple DNA extraction. The primers and probes showed a positive response with the DNA extracted from bloods infected with P. falciparum and P. vivax but not with DNA extracted from various smears from uninfected blood samples. Seven positive cases positive by both microscopy and nested PCR were found among 280 blood samples taken from in South and Southeast Iran. Five samples were identified as positive for P. vivax and two as positive for P. falciparum . All positive samples were positive by real-time PCR. Furthermore, all 38-blood samples positive by microscopy were positive by real-time PCR. No microscopy-negative samples were positive by real-time PCR. By using a simple FTA card for DNA extraction and by application of the real-time PCR developed in this study, sensitivity similar to nested-PCR and microscopy was achieved. This format simplifies the detection of Plasmodium in large numbers of samples.

Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection.

PubMed

Kho, Steven; Marfurt, Jutta; Noviyanti, Rintis; Kusuma, Andreas; Piera, Kim A; Burdam, Faustina H; Kenangalem, Enny; Lampah, Daniel A; Engwerda, Christian R; Poespoprodjo, Jeanne R; Price, Ric N; Anstey, Nicholas M; Minigo, Gabriela; Woodberry, Tonia

2015-08-01

Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The epidemiology of Plasmodium vivax and Plasmodium falciparum malaria in China, 2004-2012: from intensified control to elimination.

PubMed

Zhang, Qian; Lai, Shengjie; Zheng, Canjun; Zhang, Honglong; Zhou, Sheng; Hu, Wenbiao; Clements, Archie C A; Zhou, Xiao-Nong; Yang, Weizhong; Hay, Simon I; Yu, Hongjie; Li, Zhongjie

2014-11-03

In China, the national malaria elimination programme has been operating since 2010. This study aimed to explore the epidemiological changes in patterns of malaria in China from intensified control to elimination stages. Data on nationwide malaria cases from 2004 to 2012 were extracted from the Chinese national malaria surveillance system. The secular trend, gender and age features, seasonality, and spatial distribution by Plasmodium species were analysed. In total, 238,443 malaria cases were reported, and the proportion of Plasmodium falciparum increased drastically from <10% before 2010 to 55.2% in 2012. From 2004 to 2006, malaria showed a significantly increasing trend and with the highest incidence peak in 2006 (4.6/100,000), while from 2007 onwards, malaria decreased sharply to only 0.18/100,000 in 2012. Males and young age groups became the predominantly affected population. The areas affected by Plasmodium vivax malaria shrunk, while areas affected by P. falciparum malaria expanded from 294 counties in 2004 to 600 counties in 2012. This study demonstrated that malaria has decreased dramatically in the last five years, especially since the Chinese government launched a malaria elimination programme in 2010, and areas with reported falciparum malaria cases have expanded over recent years. These findings suggest that elimination efforts should be improved to meet these changes, so as to achieve the nationwide malaria elimination goal in China in 2020.

Indecisive Behavior of Amoeba Crossing AN Environmental Barrier

NASA Astrophysics Data System (ADS)

Takagi, S.; Nishiura, Y.; Nakagaki, T.; Ueda, T.; Ueda, K.-I.

2007-07-01

We report here a new kind of behavior that seems to be 'indecisive' in an amoeboid organism, the Physarum plasmodium of true slime mold. The plasmodium migrating in a narrow lane stops moving for a period of time (several hours but the duration differs for each plasmodium) when it encounters the presence of a chemical repellent, quinine. After stopping period, the organism suddenly begins to move again in one of three different ways as the concentration of repellent increases: going through the repulsive place (penetration), splitting into two fronts of going throught it and turning (splitting) and turning back (rebound). In relation to the physiological mechanism for tip migration in the plasmodium, we found that the frontal tip is capable of moving further although the tip is divided from a main body of organism. This means that a motive force of front locomotion is produced by a local process at the tip. Based on this finding, a mathematical model for front locomotion is considered in order to understand the dynamics for both the long period of stopping and three kinds of behavior. A model based on reaction-diffusion equations succeeds to reproduce the experimental observation. The origin of long-time stopping and three different outputs may be reduced to the hidden instabilities of internal dynamics of the pulse, which may be a skeleton structure extracted from much more complex dynamics imbedded in the Physarum plasmodium.

Control of interaction strength in a network of the true slime mold by a microfabricated structure.

PubMed

Takamatsu, A; Fujii, T; Endo, I

2000-02-01

The plasmodium of the true slime mold, Physarum polycephalum, which shows various nonlinear oscillatory phenomena, for example, in its thickness, protoplasmic streaming and concentration of intracellular chemicals, can be regarded as a collective of nonlinear oscillators. The plasmodial oscillators are interconnected by microscale tubes whose dimensions can be closely related to the strength of interaction between the oscillators. Investigation of the collective behavior of the oscillators under the conditions in which the interaction strength can be systematically controlled gives significant information on the characteristics of the system. In this study, we proposed a living model system of a coupled oscillator system in the Physarum plasmodium. We patterned the geometry and dimensions of the microscale tube structure in the plasmodium by a microfabricated structure (microstructure). As the first step, we constructed a two-oscillator system for the plasmodium that has two wells (oscillator part) and a channel (coupling part). We investigated the oscillation behavior by monitoring the thickness oscillation of the plasmodium in the microstructure with various channel widths. It was found that the oscillation behavior of two oscillators dynamically changed depending on the channel width. Based on the results of measurements of the tube dimensions and the velocity of the protoplasmic streaming in the tube, we discuss how the channel width relates to the interaction strength of the coupled oscillator system.

SAS6-like protein in Plasmodium indicates that conoid-associated apical complex proteins persist in invasive stages within the mosquito vector.

PubMed

Wall, Richard J; Roques, Magali; Katris, Nicholas J; Koreny, Ludek; Stanway, Rebecca R; Brady, Declan; Waller, Ross F; Tewari, Rita

2016-06-24

The SAS6-like (SAS6L) protein, a truncated paralogue of the ubiquitous basal body/centriole protein SAS6, has been characterised recently as a flagellum protein in trypanosomatids, but associated with the conoid in apicomplexan Toxoplasma. The conoid has been suggested to derive from flagella parts, but is thought to have been lost from some apicomplexans including the malaria-causing genus Plasmodium. Presence of SAS6L in Plasmodium, therefore, suggested a possible role in flagella assembly in male gametes, the only flagellated stage. Here, we have studied the expression and role of SAS6L throughout the Plasmodium life cycle using the rodent malaria model P. berghei. Contrary to a hypothesised role in flagella, SAS6L was absent during gamete flagellum formation. Instead, SAS6L was restricted to the apical complex in ookinetes and sporozoites, the extracellular invasive stages that develop within the mosquito vector. In these stages SAS6L forms an apical ring, as we show is also the case in Toxoplasma tachyzoites. The SAS6L ring was not apparent in blood-stage invasive merozoites, indicating that the apical complex is differentiated between the different invasive forms. Overall this study indicates that a conoid-associated apical complex protein and ring structure is persistent in Plasmodium in a stage-specific manner.

The Plasmodium serine-type SERA proteases display distinct expression patterns and non-essential in vivo roles during life cycle progression of the malaria parasite.

PubMed

Putrianti, Elyzana D; Schmidt-Christensen, Anja; Arnold, Iris; Heussler, Volker T; Matuschewski, Kai; Silvie, Olivier

2010-06-01

Parasite proteases play key roles in several fundamental steps of the Plasmodium life cycle, including haemoglobin degradation, host cell invasion and parasite egress. Plasmodium exit from infected host cells appears to be mediated by a class of papain-like cysteine proteases called 'serine repeat antigens' (SERAs). A SERA subfamily, represented by Plasmodium falciparum SERA5, contains an atypical active site serine residue instead of a catalytic cysteine. Members of this SERAser subfamily are abundantly expressed in asexual blood stages, rendering them attractive drug and vaccine targets. In this study, we show by antibody localization and in vivo fluorescent tagging with the red fluorescent protein mCherry that the two P. berghei serine-type family members, PbSERA1 and PbSERA2, display differential expression towards the final stages of merozoite formation. Via targeted gene replacement, we generated single and double gene knockouts of the P. berghei SERAser genes. These loss-of-function lines progressed normally through the parasite life cycle, suggesting a specialized, non-vital role for serine-type SERAs in vivo. Parasites lacking PbSERAser showed increased expression of the cysteine-type PbSERA3. Compensatory mechanisms between distinct SERA subfamilies may thus explain the absence of phenotypical defect in SERAser disruptants, and challenge the suitability to develop potent antimalarial drugs based on specific inhibitors of Plasmodium serine-type SERAs.

CD8 T-cell-mediated protection against liver-stage malaria: lessons from a mouse model

PubMed Central

Van Braeckel-Budimir, Natalija; Harty, John T.

2014-01-01

Malaria is a major global health problem, with severe mortality in children living in sub-Saharan Africa, and there is currently no licensed, effective vaccine. However, vaccine-induced protection from Plasmodium infection, the causative agent of malaria, was established for humans in small clinical trials and for rodents in the 1960s. Soon after, a critical role for memory CD8 T cells in vaccine-induced protection against Plasmodium liver-stage infection was established in rodent models and is assumed to apply to humans. However, these seminal early studies have led to only modest advances over the ensuing years in our understanding the basic features of memory CD8 T cells required for protection against liver-stage Plasmodium infection, an issue which has likely impeded the development of effective vaccines for humans. Given the ethical and practical limitations in gaining mechanistic insight from human vaccine and challenge studies, animal models still have an important role in dissecting the basic parameters underlying memory CD8 T-cell immunity to Plasmodium. Here, we will highlight recent data from our own work in the mouse model of Plasmodium infection that identify quantitative and qualitative features of protective memory CD8 T-cell responses. Finally, these lessons will be discussed in the context of recent findings from clinical trials of vaccine-induced protection in controlled human challenge models. PMID:24936199

Characteristics of Travel-Related Severe Plasmodium vivax and Plasmodium falciparum Malaria in Individuals Hospitalized at a Tertiary Referral Center in Lima, Peru.

PubMed

Llanos-Chea, Fiorella; Martínez, Dalila; Rosas, Angel; Samalvides, Frine; Vinetz, Joseph M; Llanos-Cuentas, Alejandro

2015-12-01

Severe Plasmodium falciparum malaria is uncommon in South America. Lima, Peru, while not endemic for malaria, is home to specialized centers for infectious diseases that admit and manage patients with severe malaria (SM), all of whom contracted infection during travel. This retrospective study describes severe travel-related malaria in individuals admitted to one tertiary care referral hospital in Lima, Peru; severity was classified based on criteria published by the World Health Organization in 2000. Data were abstracted from medical records of patients with SM admitted to Hospital Nacional Cayetano Heredia from 2006 to 2011. Of 33 SM cases with complete clinical data, the mean age was 39 years and the male/female ratio was 2.8. Most cases were contracted in known endemic regions within Peru: Amazonia (47%), the central jungle (18%), and the northern coast (12%); cases were also found in five (15%) travelers returning from Africa. Plasmodium vivax was most commonly identified (71%) among the severe infections, followed by P. falciparum (18%); mixed infections composed 11% of the group. Among the criteria of severity, jaundice was most common (58%), followed by severe thrombocytopenia (47%), hyperpyrexia (32%), and shock (15%). Plasmodium vivax mono-infection predominated as the etiology of SM in cases acquired in Peru. © The American Society of Tropical Medicine and Hygiene.

Molecular Detection of Plasmodium malariae/Plasmodium brasilianum in Non-Human Primates in Captivity in Costa Rica.

PubMed

Fuentes-Ramírez, Alicia; Jiménez-Soto, Mauricio; Castro, Ruth; Romero-Zuñiga, Juan José; Dolz, Gaby

2017-01-01

One hundred and fifty-two blood samples of non-human primates of thirteen rescue centers in Costa Rica were analyzed to determine the presence of species of Plasmodium using thick blood smears, semi-nested multiplex polymerase chain reaction (SnM-PCR) for species differentiation, cloning and sequencing for confirmation. Using thick blood smears, two samples were determined to contain the Plasmodium malariae parasite, with SnM-PCR, a total of five (3.3%) samples were positive to P. malariae, cloning and sequencing confirmed both smear samples as P. malariae. One sample amplified a larger and conserved region of 18S rDNA for the genus Plasmodium and sequencing confirmed the results obtained microscopically and through SnM-PCR tests. Sequencing and construction of a phylogenetic tree of this sample revealed that the P. malariae/P. brasilianum parasite (GenBank KU999995) found in a howler monkey (Alouatta palliata) is identical to that recently reported in humans in Costa Rica. The SnM-PCR detected P. malariae/P. brasilianum parasite in different non-human primate species in captivity and in various regions of the southern Atlantic and Pacific coast of Costa Rica. The similarity of the sequences of parasites found in humans and a monkey suggests that monkeys may be acting as reservoirs of P.malariae/P. brasilianum, for which reason it is important, to include them in control and eradication programs.

Performance of Rapid Diagnostic Tests for Imported Malaria in Clinical Practice: Results of a National Multicenter Study

PubMed Central

Houzé, Sandrine; Boutron, Isabelle; Marmorat, Anne; Dalichampt, Marie; Choquet, Christophe; Poilane, Isabelle; Godineau, Nadine; Le Guern, Anne-Sophie; Thellier, Marc; Broutier, Hélène; Fenneteau, Odile; Millet, Pascal; Dulucq, Stéphanie; Hubert, Véronique; Houzé, Pascal; Tubach, Florence; Le Bras, Jacques; Matheron, Sophie

2013-01-01

We compared the performance of four rapid diagnostic tests (RDTs) for imported malaria, and particularly Plasmodium falciparum infection, using thick and thin blood smears as the gold standard. All the tests are designed to detect at least one protein specific to P. falciparum ( Plasmodium histidine-rich protein 2 (PfHRP2) or Plasmodium LDH (PfLDH)) and one pan-Plasmodium protein (aldolase or Plasmodium LDH (pLDH)). 1,311 consecutive patients presenting to 9 French hospitals with suspected malaria were included in this prospective study between April 2006 and September 2008. Blood smears revealed malaria parasites in 374 cases (29%). For the diagnosis of P. falciparum infection, the three tests detecting PfHRP2 showed high and similar sensitivity (96%), positive predictive value (PPV) (90%) and negative predictive value (NPV) (98%). The PfLDH test showed lower sensitivity (83%) and NPV (80%), despite good PPV (98%). For the diagnosis of non-falciparum species, the PPV and NPV of tests targeting pLDH or aldolase were 94–99% and 52–64%, respectively. PfHRP2-based RDTs are thus an acceptable alternative to routine microscopy for diagnosing P. falciparum malaria. However, as malaria may be misdiagnosed with RDTs, all negative results must be confirmed by the reference diagnostic method when clinical, biological or other factors are highly suggestive of malaria. PMID:24098699

Molecular identification of Plasmodium spp. and blood meal sources of anophelines in environmental reserves on São Luís Island, state of Maranhão, Brazil.

PubMed

Figueiredo, Mayra Araguaia Pereira; Di Santi, Silvia Maria; Manrique, Wilson Gómez; Gonçalves, Luiz Ricardo; André, Marcos Rogério; Machado, Rosangela Zacarias

2017-04-26

Considering the diversity of feeding habits that females of some species of anophelines present, it is important to understand which vertebrates are part of blood food sources and how important is the role of each in the ecoepidemiology of malaria. There are many vector species for Plasmodium spp. in the State of Maranhão, Brazil. In São Luís Island, Anopheles aquasalis is the main vector for human malaria; this species is abundant in areas with primates that are positive for Plasmodium. Anopheles aquasalis has natural exophilic and zoophilic feeding behavior, but in cases of high density and absence of animals, presents quite varied behavior, and feeds on human blood. In this context, the objective of the present study was to identify Plasmodium spp. and the blood meal sources of anophelines in two environmental reserves on São Luís Island, state of Maranhão, using molecular methods. Between June and July 2013, female anophelines were collected in the Sítio Aguahy Private Reserve, in the municipality of São José de Ribamar, and in the Sítio Mangalho Reserve, located within the Maracanã Environmental Protection Area, in the municipality of São Luís. CDC-type light traps, Shannon traps and protected human bait were used during three consecutive hours in peridomestic and wooded areas. Pools of anophelines were formed using mosquitoes of the same species that had been caught at the same site on the same date. A genus-specific amplification protocol based on the 18S rRNA gene was used for qPCR and cPCR. A total of 416 anophelines were collected, of the following species: An. aquasalis (399), An. mediopunctatus (3), An. shannoni (1), An. nuneztovari (sensu lato) (1), An. goeldii (1), An. evansae (2) and An. (Nyssorhynchus) sp. (9), comprising 54 pools. Two pools were positive for Plasmodium (2/54) based on the 18S rRNA gene. In the phylogenetic analysis using the maximum likelihood method, based on a 240 bp fragment of the 18S rRNA gene, it was found that the sequences of Plasmodium sp. amplified from pools of An. aquasalis (pool 2) and An. nuneztovari (s.l.) (pool 10) were phylogenetically related to a clade of P. falciparum isolates from India, and to a clade of Plasmodium sp. isolates from psittacines in Brazil, respectively. Cat, dog and human DNA were identified in the blood meals of the anophelines sampled. The species An. aquasalis was the most abundant anopheline species in São Luís Island. Plasmodium spp. DNA was detected, thus confirming the importance of this species as the main vector on São Luís Island, Brazil. In addition, the presence of An. nuneztovari (s.l.) with DNA positive for Plasmodium spp. confirms its importance as a secondary vector.

Plasmodium falciparum infection increases Anopheles gambiae attraction to nectar sources and sugar uptake

USDA-ARS?s Scientific Manuscript database

Plasmodium parasites are known to manipulate the behaviour of their vectors so as to enhance their transmission. However, it is unknown if this vector manipulation also affects mosquito-plant interaction and sugar uptake. Dual-choice olfactometer and probing assays were used to study plant seeking b...

Molecular Factors and Biological Pathways Associated with Malaria Fever and the Pathogenesis of Cerebral Malaria

DTIC Science & Technology

2007-04-09

Novakovic , P. Gerold, R. T. Schwarz, M. J. McConville, and S. D. Tachado. 1996. Glycosylphosphatidylinositol toxin of Plasmodium up-regulates...Schofield, L., S. Novakovic , P. Gerold, R. T. Schwarz, M. J. McConville, and S. D. Tachado. 1996. Glycosylphosphatidylinositol toxin of Plasmodium up

Plasmodium falciparum Malaria, Southern Algeria, 2007

PubMed Central

Gassen, Ibrahim; Khechache, Yacine; Lamali, Karima; Tchicha, Boualem; Brengues, Cécile; Menegon, Michela; Severini, Carlo; Fontenille, Didier; Harrat, Zoubir

2010-01-01

An outbreak of Plasmodium falciparum malaria occurred in Tinzaouatine in southern Algeria in 2007. The likely vector, Anopheles gambiae mosquitoes, had not been detected in Algeria. Genes for resistance to chloroquine were detected in the parasite. The outbreak shows the potential for an increase in malaria vectors in Algeria. PMID:20113565

21 CFR 866.3402 - Plasmodium species antigen detection assays.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3402...

21 CFR 866.3402 - Plasmodium species antigen detection assays.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3402...

21 CFR 866.3402 - Plasmodium species antigen detection assays.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3402...

21 CFR 866.3402 - Plasmodium species antigen detection assays.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3402...

21 CFR 866.3402 - Plasmodium species antigen detection assays.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Plasmodium species antigen detection assays. 866.3402 Section 866.3402 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3402...

Source identification of autochthonous-introduced Plasmodium vivax Malaria, Spain.

PubMed

Barrado, Laura; Ezpeleta, Carmen; Rubio, José Miguel; Martín, Carmen; Azcona, José Manuel; Arteaga, Miren; Beristain, Xabier; Navascués, Ana; Ongay, Eva; Castilla, Jesús

2017-02-01

In 2014, an autochthonous case of introduced malaria caused by Plasmodium vivax was identified in Spain. The strain that infected this patient was identical to that of a prior imported case from Pakistan. This is the first case where the source of infection could be identified since elimination in Spain.

Ingested human insulin inhibits the mosquito NF-¿B-dependent immune response to Plasmodium falciparum

USDA-ARS?s Scientific Manuscript database

We showed previously that ingested human insulin activates the insulin/IGF-1 signaling pathway in Anopheles stephensi and increases the susceptibility of these mosquitoes to Plasmodium falciparum. In other organisms insulin can alter immune responsiveness through regulation of NF-kB transcription fa...

Plasmodium vivax Malaria among military personnel, French Guiana, 1998-2008.

PubMed

Queyriaux, Benjamin; Texier, Gaetan; Ollivier, Lenaick; Galoisy-Guibal, Laurent; Michel, Remy; Meynard, Jean-Baptiste; Decam, Christophe; Verret, Catherine; Pommier de Santi, Vincent; Spiegel, Andre; Boutin, Jean-Paul; Migliani, Rene; Deparis, Xavier

2011-07-01

We obtained health surveillance epidemiologic data on malaria among French military personnel deployed to French Guiana during 1998-2008. Incidence of Plasmodium vivax malaria increased and that of P. falciparum remained stable. This new epidemiologic situation has led to modification of malaria treatment for deployed military personnel.

Prolonged Plasmodium falciparum Infection in Immigrants, Paris

PubMed Central

Godineau, Nadine; Fontanet, Arnaud; Houze, Sandrine; Bouchaud, Olivier; Matheron, Sophie; Le Bras, Jacques

2008-01-01

Few immigrant travelers have Plasmodium falciparum infections >2 months after leaving malaria-endemic areas. We conducted a case–control study to identify factors associated with prolonged P. falciparum infection in immigrant travelers. Results suggest that P. falciparum infection should be systematically suspected, even months after travel, especially in pregnant women and first-arrival immigrants. PMID:18258132

Treatment Failure of Dihydroartemisinin/Piperaquine for Plasmodium falciparum Malaria, Vietnam.

PubMed

Phuc, Bui Quang; Rasmussen, Charlotte; Duong, Tran Thanh; Dong, Le Than; Loi, Mai Anh; Ménard, Didier; Tarning, Joel; Bustos, Dorina; Ringwald, Pascal; Galappaththy, Gawrie Loku; Thieu, Nguyen Quang

2017-04-01

We conducted a study in Binh Phuoc, Vietnam, in 2015 on the therapeutic efficacy of dihydroartemisinin/piperaquine for Plasmodium falciparum malaria. A high number of treatment failures (14/40) was found, and piperaquine resistance in Vietnam was confirmed. A change in the malaria treatment policy for Vietnam is in process.

Two-Color Flow Cytometric Analysis of Intraerythrocytic Malaria Parasite DNA and Surface Membrane-Associated Antigen in Erythrocytes Infected with Plasmodium falciparum

DTIC Science & Technology

1993-01-01

Antigen in Erythrocytes Infected With Plasmodium falciparum 1 Kovit Pattanapanyasat,2 Rachanee Udomsangpetch, and H. Kyle Webster The Thalassemia Center... Thalassemia Center, Division of Hematology., Siriraj Hospital, 15). Identification of conserved epitopes has important Bangkok 10700. Thailan 93-10832 93 5 4

Structure and Function of Plasmodium falciparum malate dehydrogenase: Role of Critical Amino Acids in C-substrate Binding Procket

USDA-ARS?s Scientific Manuscript database

Malaria parasite thrives on anaerobic fermentation of glucose for energy. Earlier studies from our lab have demonstrated that a cytosolic malate dehydrogenase (PfMDH) with striking similarity to lactate dehydrogenase (PfLDH) might complement PfLDH function in Plasmodium falciparum. The N-terminal g...

Plasmodium vivax Malaria among Military Personnel, French Guiana, 1998–2008

PubMed Central

Texier, Gaëtan; Ollivier, Lénaïck; Galoisy-Guibal, Laurent; Michel, Rémy; Meynard, Jean-Baptiste; Decam, Christophe; Verret, Catherine; Pommier de Santi, Vincent; Spiegel, André; Boutin, Jean-Paul; Migliani, René; Deparis, Xavier

2011-01-01

We obtained health surveillance epidemiologic data on malaria among French military personnel deployed to French Guiana during 1998–2008. Incidence of Plasmodium vivax malaria increased and that of P. falciparum remained stable. This new epidemiologic situation has led to modification of malaria treatment for deployed military personnel. PMID:21762587

Motility and infectivity of Plasmodium berghei sporozoites expressing avian Plasmodium gallinaceum circumsporozoite protein.

PubMed

Tewari, Rita; Rathore, Dharmendar; Crisanti, Andrea

2005-05-01

Avian and rodent malaria sporozoites selectively invade different vertebrate cell types, namely macrophages and hepatocytes, and develop in distantly related vector species. To investigate the role of the circumsporozoite (CS) protein in determining parasite survival in different vector species and vertebrate host cell types, we replaced the endogenous CS protein gene of the rodent malaria parasite Plasmodium berghei with that of the avian parasite P. gallinaceum and control rodent parasite P. yoelii. In anopheline mosquitoes, P. berghei parasites carrying P. gallinaceum and rodent parasite P. yoelii CS protein gene developed into oocysts and sporozoites. Plasmodium gallinaceum CS expressing transgenic sporozoites, although motile, failed to invade mosquito salivary glands and to infect mice, which suggests that motility alone is not sufficient for invasion. Notably, a percentage of infected Anopheles stephensi mosquitoes showed melanotic encapsulation of late stage oocysts. This was not observed in control infections or in A. gambiae infections. These findings shed new light on the role of the CS protein in the interaction of the parasite with both the mosquito vector and the rodent host.

Using genetic methods to define the targets of compounds with antimalarial activity

PubMed Central

Flannery, Erika L.; Fidock, David A.; Winzeler, Elizabeth A.

2013-01-01

Although phenotypic cellular screening has been used to drive antimalarial drug discovery in recent years, in some cases target-based drug discovery remains more attractive. This is especially true when appropriate high-throughput cellular assays are lacking, as is the case for drug discovery efforts that aim to provide a replacement for primaquine (4-N-(6-methoxyquinolin-8-yl)pentane-1,4-diamine), the only drug that can block Plasmodium transmission to Anopheles mosquitoes and eliminate liver-stage hypnozoites. At present, however, there are no known chemically validated parasite protein targets that are important in all Plasmodium parasite developmental stages and that can be used in traditional biochemical compound screens. We propose that a plethora of novel, chemically validated, cross-stage antimalarial targets still remain to be discovered from the ~5,500 proteins encoded by the Plasmodium genomes. Here we discuss how in vitro evolution of drug-resistant strains of Plasmodium falciparum and subsequent whole-genome analysis can be used to find the targets of some of the many compounds discovered in whole-cell phenotypic screens. PMID:23927658

Trafficking of the signature protein of intra-erythrocytic Plasmodium berghei-induced structures, IBIS1, to P. falciparum Maurer's clefts.

PubMed

Petersen, Wiebke; Matuschewski, Kai; Ingmundson, Alyssa

2015-01-01

Remodeling of the host red blood cell by Plasmodium falciparum is well established and crucial for infection and parasite virulence. Host cell modifications are not exclusive to human Plasmodium parasites and also occur in hepatocytes and erythrocytes infected with murine Plasmodium parasites. The recently described intra-erythrocytic P. berghei-induced structures (IBIS) share similarities to P. falciparum Maurer's clefts. It is shown here that a potential candidate IBIS1 homologue in P. falciparum, PfHYP12 (PF3D7_1301400), is partially exported into the erythrocyte cytoplasm. To analyze a potential similarity between IBIS and Maurer's clefts we expressed the signature protein of IBIS in P. falciparum parasites. Visualization of the tagged protein revealed that PbIBIS1 can be exported by P. falciparum and localizes to Maurer's clefts in P. falciparum-infected erythrocytes, which indicates that IBIS and Maurer's clefts may be evolutionarily conserved parasite-induced structures in infected erythrocytes. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Buffer Optimization of Thermal Melt Assays of Plasmodium Proteins for Detection of Small-Molecule Ligands

PubMed Central

Crowther, Gregory J.; Napuli, Alberto J.; Thomas, Andrew P.; Chung, Diana J.; Kovzun, Kuzma V.; Leibly, David J.; Castaneda, Lisa J.; Bhandari, Janhavi; Damman, Christopher J.; Hui, Raymond; Hol, Wim G. J.; Buckner, Frederick S.; Verlinde, Christophe L. M. J.; Zhang, Zhongsheng; Fan, Erkang; Van Voorhis, Wesley C.

2010-01-01

In the last decade, thermal melt/thermal shift assays have become a common tool for identifying ligands and other factors that stabilize specific proteins. Increased stability is indicated by an increase in the protein's melting temperature (Tm). In optimizing the assays for subsequent screening of compound libraries, it is important to minimize the variability of Tm measurements so as to maximize the assay's ability to detect potential ligands. Here we present an investigation of Tm variability in recombinant proteins from Plasmodium parasites. Ligands of Plasmodium proteins are particularly interesting as potential starting points for drugs for malaria, and new drugs are urgently needed. A single standard buffer (100 mM HEPES, pH 7.5, 150 mM NaCl) permitted estimation of Tm for 58 of 61 Plasmodium proteins tested. However, with several proteins, Tm could not be measured with a consistency suitable for high-throughput screening unless alternative protein-specific buffers were employed. We conclude that buffer optimization to minimize variability in Tm measurements increases the success of thermal melt screens involving proteins for which a standard buffer is suboptimal. PMID:19470714

Prevalence of malaria parasites (Plasmodium floridense and Plasmodium azurophilum) infecting a Puerto Rican lizard (Anolis gundlachi): a nine-year study.

PubMed

Schall, J J; Pearson, A R; Perkins, S L

2000-06-01

The prevalence of malaria parasites was studied in the lizard Anolis gundlachi over a 9-yr period at a site in the wet evergreen forest of eastern Puerto Rico. Three forms of the parasite infected the lizards; these were Plasmodium floridense, Plasmodium azurophilum in erythrocytes, and P. azurophilum in white blood cells. Overall prevalence of infection for 8 samples during the study period was significantly higher for males than females (32% of 3,296 males and 22% of 1,439 females). During the study, the site experienced substantial climatic and physical disturbance including rising temperature, droughts, and hurricanes that severely damaged the forest. Parasite prevalence in the first sample, 8 mo after the massive hurricane Hugo, was slightly, though significantly, lower than for subsequent samples. However, overall prevalence was stable during the 9-yr period. The results show malaria prevalence is more constant at the site than found for 2 studies in temperate forests, and that the Puerto Rico system may be an example of the stable, endemic malaria described by standard models for human malaria epidemiology.

Torins are potent antimalarials that block replenishment of Plasmodium liver stage parasitophorous vacuole membrane proteins

PubMed Central

Hanson, Kirsten K.; Ressurreição, Ana S.; Buchholz, Kathrin; Prudêncio, Miguel; Herman-Ornelas, Jonathan D.; Rebelo, Maria; Beatty, Wandy L.; Wirth, Dyann F.; Hänscheid, Thomas; Moreira, Rui; Marti, Matthias; Mota, Maria M.

2013-01-01

Residence within a customized vacuole is a highly successful strategy used by diverse intracellular microorganisms. The parasitophorous vacuole membrane (PVM) is the critical interface between Plasmodium parasites and their possibly hostile, yet ultimately sustaining, host cell environment. We show that torins, developed as ATP-competitive mammalian target of rapamycin (mTOR) kinase inhibitors, are fast-acting antiplasmodial compounds that unexpectedly target the parasite directly, blocking the dynamic trafficking of the Plasmodium proteins exported protein 1 (EXP1) and upregulated in sporozoites 4 (UIS4) to the liver stage PVM and leading to efficient parasite elimination by the hepatocyte. Torin2 has single-digit, or lower, nanomolar potency in both liver and blood stages of infection in vitro and is likewise effective against both stages in vivo, with a single oral dose sufficient to clear liver stage infection. Parasite elimination and perturbed trafficking of liver stage PVM-resident proteins are both specific aspects of torin-mediated Plasmodium liver stage inhibition, indicating that torins have a distinct mode of action compared with currently used antimalarials. PMID:23836641

Spontaneous switching of frequency-locking by periodic stimulus in oscillators of plasmodium of the true slime mold.

PubMed

Takamatsu, A; Yamamoto, T; Fujii, T

2004-01-01

Microfabrication technique was used to construct a model system with a living cell of plasmodium of the true slime mold, Physarum polycephalum, a living coupled oscillator system. Its parameters can be systematically controlled as in computer simulations, so that results are directly comparable to those of general mathematical models. As the first step, we investigated responses in oscillatory cells, the oscillators of the plasmodium, to periodic stimuli by temperature changes to elucidate characteristics of the cells as nonlinear systems whose internal dynamics are unknown because of their complexity. We observed that the forced oscillator of the plasmodium show 1:1, 2:1, 3:1 frequency locking inside so-called Arnold tongues regions as well as in other nonlinear systems such as chemical systems and other biological systems. In addition, we found spontaneous switching behavior from certain frequency locking states to other states, even under certain fixed parameters. This technique can be applied to more complex systems with multiple elements, such as coupled oscillator systems, and would be useful to investigate complicated phenomena in biological systems such as information processing.

Targeted Deletion of a Plasmodium Site-2 Protease Impairs Life Cycle Progression in the Mammalian Host

PubMed Central

Goulielmaki, Evi; Chalari, Anna; Withers-Martinez, Chrislaine; Siden-Kiamos, Inga; Matuschewski, Kai

2017-01-01

Site-2 proteases (S2P) belong to the M50 family of metalloproteases, which typically perform essential roles by mediating activation of membrane–bound transcription factors through regulated intramembrane proteolysis (RIP). Protease-dependent liberation of dormant transcription factors triggers diverse cellular responses, such as sterol regulation, Notch signalling and the unfolded protein response. Plasmodium parasites rely on regulated proteolysis for controlling essential pathways throughout the life cycle. In this study we examine the Plasmodium-encoded S2P in a murine malaria model and show that it is expressed in all stages of Plasmodium development. Localisation studies by endogenous gene tagging revealed that in all invasive stages the protein is in close proximity to the nucleus. Ablation of PbS2P by reverse genetics leads to reduced growth rates during liver and blood infection and, hence, virulence attenuation. Strikingly, absence of PbS2P was compatible with parasite life cycle progression in the mosquito and mammalian hosts under physiological conditions, suggesting redundant or dispensable roles in vivo. PMID:28107409

Targeted Deletion of a Plasmodium Site-2 Protease Impairs Life Cycle Progression in the Mammalian Host.

PubMed

Koussis, Konstantinos; Goulielmaki, Evi; Chalari, Anna; Withers-Martinez, Chrislaine; Siden-Kiamos, Inga; Matuschewski, Kai; Loukeris, Thanasis G

2017-01-01

Site-2 proteases (S2P) belong to the M50 family of metalloproteases, which typically perform essential roles by mediating activation of membrane-bound transcription factors through regulated intramembrane proteolysis (RIP). Protease-dependent liberation of dormant transcription factors triggers diverse cellular responses, such as sterol regulation, Notch signalling and the unfolded protein response. Plasmodium parasites rely on regulated proteolysis for controlling essential pathways throughout the life cycle. In this study we examine the Plasmodium-encoded S2P in a murine malaria model and show that it is expressed in all stages of Plasmodium development. Localisation studies by endogenous gene tagging revealed that in all invasive stages the protein is in close proximity to the nucleus. Ablation of PbS2P by reverse genetics leads to reduced growth rates during liver and blood infection and, hence, virulence attenuation. Strikingly, absence of PbS2P was compatible with parasite life cycle progression in the mosquito and mammalian hosts under physiological conditions, suggesting redundant or dispensable roles in vivo.

DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

PubMed Central

Lee, Andrew H.; Symington, Lorraine S.

2014-01-01

SUMMARY Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium. Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium. Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum. These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen. PMID:25184562

Prevalence of PCR detectable malaria infection among febrile patients with a negative Plasmodium falciparum specific rapid diagnostic test in Zanzibar.

PubMed

Baltzell, Kimberly A; Shakely, Deler; Hsiang, Michelle; Kemere, Jordan; Ali, Abdullah Suleiman; Björkman, Anders; Mårtensson, Andreas; Omar, Rahila; Elfving, Kristina; Msellem, Mwinyi; Aydin-Schmidt, Berit; Rosenthal, Philip J; Greenhouse, Bryan

2013-02-01

We screened for malaria in 594 blood samples from febrile patients who tested negative by a Plasmodium falciparum-specific histidine-rich protein-2-based rapid diagnostic test at 12 health facilities in Zanzibar districts North A and Micheweni, from May to August 2010. Screening was with microscopy, polymerase chain reaction (PCR) targeting the cytochrome b gene (cytbPCR) of the four major human malaria species, and quantitative PCR (qPCR). The prevalence of cytbPCR-detectable malaria infection was 2% (12 of 594), including 8 P. falciparum, 3 Plasmodium malariae, and 1 Plasmodium vivax infections. Microscopy identified 4 of 8 P. falciparum infections. Parasite density as estimated by microscopy or qPCR was > 4,000 parasites/μL in 5 of 8 cytbPCR-detectable P. falciparum infections. The infections that were missed by the rapid diagnostic test represent a particular challenge in malaria elimination settings and highlight the need for more sensitive point-of-care diagnostic tools to improve case detection of all human malaria species in febrile patients.

Chronicle of a death foretold: Plasmodium liver stage parasites decide on the fate of the host cell.

PubMed

Graewe, Stefanie; Stanway, Rebecca R; Rennenberg, Annika; Heussler, Volker T

2012-01-01

Protozoan parasites of the genus Plasmodium are the causative agents of malaria. Despite more than 100 years of research, the complex life cycle of the parasite still bears many surprises and it is safe to say that understanding the biology of the pathogen will keep scientists busy for many years to come. Malaria research has mainly concentrated on the pathological blood stage of Plasmodium parasites, leaving us with many questions concerning parasite development within the mosquito and during the exo-erythrocytic stage in the vertebrate host. After the discovery of the Plasmodium liver stage in the middle of the last century, it remained understudied for many years but the realization that it represents a promising target for vaccination approaches has brought it back into focus. The last decade saw many new and exciting discoveries concerning the exo-erythrocytic stage and in this review we will discuss the highlights of the latest developments in the field. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Development of a chimeric Plasmodium berghei strain expressing the repeat region of the P. vivax circumsporozoite protein for in vivo evaluation of vaccine efficacy.

PubMed

Espinosa, Diego A; Yadava, Anjali; Angov, Evelina; Maurizio, Paul L; Ockenhouse, Christian F; Zavala, Fidel

2013-08-01

The development of vaccine candidates against Plasmodium vivax-the most geographically widespread human malaria species-is challenged by technical difficulties, such as the lack of in vitro culture systems and availability of animal models. Chimeric rodent Plasmodium parasites are safe and useful tools for the preclinical evaluation of new vaccine formulations. We report the successful development and characterization of chimeric Plasmodium berghei parasites bearing the type I repeat region of P. vivax circumsporozoite protein (CSP). The P. berghei-P. vivax chimeric strain develops normally in mosquitoes and produces highly infectious sporozoites that produce patent infection in mice that are exposed to the bites of as few as 3 P. berghei-P. vivax-infected mosquitoes. Using this transgenic parasite, we demonstrate that monoclonal and polyclonal antibodies against P. vivax CSP strongly inhibit parasite infection and thus support the notion that these antibodies play an important role in protective immunity. The chimeric parasites we developed represent a robust model for evaluating protective immune responses against P. vivax vaccines based on CSP.

High rate of adaptation of mammalian proteins that interact with Plasmodium and related parasites

PubMed Central

Telis, Natalie; Petrov, Dmitri A.

2017-01-01

Plasmodium parasites, along with their Piroplasm relatives, have caused malaria-like illnesses in terrestrial mammals for millions of years. Several Plasmodium-protective alleles have recently evolved in human populations, but little is known about host adaptation to blood parasites over deeper evolutionary timescales. In this work, we analyze mammalian adaptation in ~500 Plasmodium- or Piroplasm- interacting proteins (PPIPs) manually curated from the scientific literature. We show that (i) PPIPs are enriched for both immune functions and pleiotropy with other pathogens, and (ii) the rate of adaptation across mammals is significantly elevated in PPIPs, compared to carefully matched control proteins. PPIPs with high pathogen pleiotropy show the strongest signatures of adaptation, but this pattern is fully explained by their immune enrichment. Several pieces of evidence suggest that blood parasites specifically have imposed selection on PPIPs. First, even non-immune PPIPs that lack interactions with other pathogens have adapted at twice the rate of matched controls. Second, PPIP adaptation is linked to high expression in the liver, a critical organ in the parasite life cycle. Finally, our detailed investigation of alpha-spectrin, a major red blood cell membrane protein, shows that domains with particularly high rates of adaptation are those known to interact specifically with P. falciparum. Overall, we show that host proteins that interact with Plasmodium and Piroplasm parasites have experienced elevated rates of adaptation across mammals, and provide evidence that some of this adaptation has likely been driven by blood parasites. PMID:28957326

Plasmodium parasite as an effective hepatocellular carcinoma antigen glypican-3 delivery vector.

PubMed

Liu, Quan; Yang, Yijun; Tan, Xuefang; Tao, Zhu; Adah, Dickson; Yu, Songlin; Lu, Junnan; Zhao, Siting; Qin, Limei; Qin, Li; Chen, Xiaoping

2017-04-11

We have previously demonstrated that malaria parasite infection has an anti-tumor effect in a mouse model. This research aimed to investigate the possibility of using Plasmodium parasite as a novel vaccine vector for hepatocellular carcinoma (HCC) immunotherapy. We constructed a Plasmodium yoelii 17XNL strain (P.y) expressing murine glypican-3 (GPC3) protein (P.y-GPC3), and examined its therapeutic potency in a murine Hepa1-6-induced hepatoma model that highly expressed GPC3 protein. The prerequisites for invoking a CD8+ T cell response were assessed after P.y-based immunization, which included obviously increased concentrations of T helper cell type 1 (Th1)-associated cytokines, such as IL-2, IFN-γ and TNF-α, in serum and preferential expansion of the CD8α+ dendritic cell (DC) subset with higher expression of CD80 and CD86 molecules. Compared with uninfected and wild-type P.y-infected mice, a significant GPC3-specific cytotoxic T lymphocyte (CTL) response was detected in P.y-GPC3 vaccinated mice. Furthermore, P.y-GPC3-based vaccination dramatically inhibited Hepa1-6-induced tumor growth in the implanted HCC and prolonged the survival of tumor-bearing mice. We concluded that a Plasmodium-based vector is highly efficient in inducing tumor antigen-specific T cell-mediated immunity and protection against tumor cells. More broadly, this strategy supported our hypothesis that Plasmodium parasites, as novel therapeutic antigen vectors, may be applicable to tumor immunotherapy for patients with HCC.

Molecular Detection of Plasmodium malariae/Plasmodium brasilianum in Non-Human Primates in Captivity in Costa Rica

PubMed Central

Fuentes-Ramírez, Alicia; Jiménez-Soto, Mauricio; Castro, Ruth; Romero-Zuñiga, Juan José

2017-01-01

One hundred and fifty-two blood samples of non-human primates of thirteen rescue centers in Costa Rica were analyzed to determine the presence of species of Plasmodium using thick blood smears, semi-nested multiplex polymerase chain reaction (SnM-PCR) for species differentiation, cloning and sequencing for confirmation. Using thick blood smears, two samples were determined to contain the Plasmodium malariae parasite, with SnM-PCR, a total of five (3.3%) samples were positive to P. malariae, cloning and sequencing confirmed both smear samples as P. malariae. One sample amplified a larger and conserved region of 18S rDNA for the genus Plasmodium and sequencing confirmed the results obtained microscopically and through SnM-PCR tests. Sequencing and construction of a phylogenetic tree of this sample revealed that the P. malariae/P. brasilianum parasite (GenBank KU999995) found in a howler monkey (Alouatta palliata) is identical to that recently reported in humans in Costa Rica. The SnM-PCR detected P. malariae/P. brasilianum parasite in different non-human primate species in captivity and in various regions of the southern Atlantic and Pacific coast of Costa Rica. The similarity of the sequences of parasites found in humans and a monkey suggests that monkeys may be acting as reservoirs of P.malariae/P. brasilianum, for which reason it is important, to include them in control and eradication programs. PMID:28125696

The aspartyl protease TgASP5 mediates the export of the Toxoplasma GRA16 and GRA24 effectors into host cells.

PubMed

Curt-Varesano, Aurélie; Braun, Laurence; Ranquet, Caroline; Hakimi, Mohamed-Ali; Bougdour, Alexandre

2016-02-01

Toxoplasma gondii and Plasmodium species are obligatory intracellular parasites that export proteins into the infected cells in order to interfere with host-signalling pathways, acquire nutrients or evade host defense mechanisms. With regard to export mechanism, a wealth of information in Plasmodium spp. is available, while the mechanisms operating in T. gondii remain uncertain. The recent discovery of exported proteins in T. gondii, mainly represented by dense granule resident proteins, might explain this discrepancy and offers a unique opportunity to study the export mechanism in T. gondii. Here, we report that GRA16 export is mediated by two protein elements present in its N-terminal region. Because the first element contains a putative Plasmodium export element linear motif (RRLAE), we hypothesized that GRA16 export depended on a maturation process involving protein cleavage. Using both N- and C-terminal epitope tags, we provide evidence for protein proteolysis occurring in the N-terminus of GRA16. We show that TgASP5, the T. gondii homolog of Plasmodium plasmepsin V, is essential for GRA16 export and is directly responsible for its maturation in a Plasmodium export element-dependent manner. Interestingly, TgASP5 is also involved in GRA24 export, although the GRA24 maturation mechanism is TgASP5-independent. Our data reveal different modus operandi for protein export, in which TgASP5 should play multiple functions. © 2015 John Wiley & Sons Ltd.

The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin

PubMed Central

Kumar, Rajinder; Musiyenko, Alla; Barik, Sailen

2003-01-01

Background The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA), is a specific inhibitor of heat shock protein 90 (Hsp90) and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. Results We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ) under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively) and on all erythrocytic stages of the parasite. Conclusions Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug. PMID:14514358

The heat shock protein 90 of Plasmodium falciparum and antimalarial activity of its inhibitor, geldanamycin.

PubMed

Kumar, Rajinder; Musiyenko, Alla; Barik, Sailen

2003-09-15

The naturally occurring benzoquinone ansamycin compound, geldanamycin (GA), is a specific inhibitor of heat shock protein 90 (Hsp90) and is a potential anticancer agent. Since Plasmodium falciparum has been reported to have an Hsp90 ortholog, we tested the possibility that GA might inhibit it and thereby display antiparasitic activity. We provide direct recombinant DNA evidence for the Hsp90 protein of Plasmodium falciparum, the causative agent of fatal malaria. While the mRNA of Hsp90 was mainly expressed in ring and trophozoite stages, the protein was found in all stages, although schizonts contained relatively lower amounts. In vitro the parasitic Hsp90 exhibited an ATP-binding activity that could be specifically inhibited by GA. Plasmodium growth in human erythrocyte culture was strongly inhibited by GA with an IC50 of 20 nM, compared to the IC50 of 15 nM for chloroquine (CQ) under identical conditions. When used in combination, the two drugs acted synergistically. GA was equally effective against CQ-sensitive and CQ-resistant strains (3D7 and W2, respectively) and on all erythrocytic stages of the parasite. Together, these results suggest that an active and essential Hsp90 chaperone cycle exists in Plasmodium and that the ansamycin antibiotics will be an important tool to dissect its role in the parasite. Additionally, the favorable pharmacology of GA, reported in human trials, makes it a promising antimalarial drug.

Simplified Pan-species Real-time PCR-based Detection of Plasmodium Spp. in Blood Smear

PubMed Central

HASSANPOUR, Gholamreza; MIRHENDI, Hossein; MOHEBALI, Mehdi; RAEISI, Ahmad; ZERAATI, Hojjat; KESHAVARZ, Hossein

2016-01-01

Background: We aimed to quicken and simplify the detection of Plasmodium in blood samples by developing and testing a pan-Plasmodium real-time PCR for accurate screening of individuals suspected of malaria. Methods: A single primer/probe set for pan-species Plasmodium-specific real time PCR targeting a conserved region of the small subunit 18S ribosomal DNA was designed and evaluated for rapid diagnosis and screening of malaria infections using dried blood smears. FTA cards were used for rapid and simple DNA extraction. Results: The primers and probes showed a positive response with the DNA extracted from bloods infected with P. falciparum and P. vivax but not with DNA extracted from various smears from uninfected blood samples. Seven positive cases positive by both microscopy and nested PCR were found among 280 blood samples taken from in South and Southeast Iran. Five samples were identified as positive for P. vivax and two as positive for P. falciparum. All positive samples were positive by real-time PCR. Furthermore, all 38-blood samples positive by microscopy were positive by real-time PCR. No microscopy-negative samples were positive by real-time PCR. Conclusion: By using a simple FTA card for DNA extraction and by application of the real-time PCR developed in this study, sensitivity similar to nested-PCR and microscopy was achieved. This format simplifies the detection of Plasmodium in large numbers of samples. PMID:28127357

Plasmodium falciparum CRK4 directs continuous rounds of DNA replication during schizogony.

PubMed

Ganter, Markus; Goldberg, Jonathan M; Dvorin, Jeffrey D; Paulo, Joao A; King, Jonas G; Tripathi, Abhai K; Paul, Aditya S; Yang, Jing; Coppens, Isabelle; Jiang, Rays H Y; Elsworth, Brendan; Baker, David A; Dinglasan, Rhoel R; Gygi, Steven P; Duraisingh, Manoj T

2017-02-17

Plasmodium parasites, the causative agents of malaria, have evolved a unique cell division cycle in the clinically relevant asexual blood stage of infection 1 . DNA replication commences approximately halfway through the intracellular development following invasion and parasite growth. The schizont stage is associated with multiple rounds of DNA replication and nuclear division without cytokinesis, resulting in a multinucleated cell. Nuclei divide asynchronously through schizogony, with only the final round of DNA replication and segregation being synchronous and coordinated with daughter cell assembly 2,3 . However, the control mechanisms for this divergent mode of replication are unknown. Here, we show that the Plasmodium-specific kinase PfCRK4 is a key cell-cycle regulator that orchestrates multiple rounds of DNA replication throughout schizogony in Plasmodium falciparum. PfCRK4 depletion led to a complete block in nuclear division and profoundly inhibited DNA replication. Quantitative phosphoproteomic profiling identified a set of PfCRK4-regulated phosphoproteins with greatest functional similarity to CDK2 substrates, particularly proteins involved in the origin of replication firing. PfCRK4 was required for initial and subsequent rounds of DNA replication during schizogony and, in addition, was essential for development in the mosquito vector. Our results identified an essential S-phase promoting factor of the unconventional P. falciparum cell cycle. PfCRK4 is required for both a prolonged period of the intraerythrocytic stage of Plasmodium infection, as well as for transmission, revealing a broad window for PfCRK4-targeted chemotherapeutics.

Acute respiratory distress syndrome and acute renal failure from Plasmodium ovale infection with fatal outcome.

PubMed

Lau, Yee-Ling; Lee, Wenn-Chyau; Tan, Lian-Huat; Kamarulzaman, Adeeba; Syed Omar, Sharifah Faridah; Fong, Mun-Yik; Cheong, Fei-Wen; Mahmud, Rohela

2013-11-04

Plasmodium ovale is one of the causative agents of human malaria. Plasmodium ovale infection has long been thought to be non-fatal. Due to its lower morbidity, P. ovale receives little attention in malaria research. Two Malaysians went to Nigeria for two weeks. After returning to Malaysia, they fell sick and were admitted to different hospitals. Plasmodium ovale parasites were identified from blood smears of these patients. The species identification was further confirmed with nested PCR. One of them was successfully treated with no incident of relapse within 12-month medical follow-up. The other patient came down with malaria-induced respiratory complication during the course of treatment. Although parasites were cleared off the circulation, the patient's condition worsened. He succumbed to multiple complications including acute respiratory distress syndrome and acute renal failure. Sequencing of the malaria parasite DNA from both cases, followed by multiple sequence alignment and phylogenetic tree construction suggested that the causative agent for both malaria cases was P. ovale curtisi. In this report, the differences between both cases were discussed, and the potential capability of P. ovale in causing severe complications and death as seen in this case report was highlighted. Plasmodium ovale is potentially capable of causing severe complications, if not death. Complete travel and clinical history of malaria patient are vital for successful diagnoses and treatment. Monitoring of respiratory and renal function of malaria patients, regardless of the species of malaria parasites involved is crucial during the course of hospital admission.

Inference of the oxidative stress network in Anopheles stephensi upon Plasmodium infection.

PubMed

Shrinet, Jatin; Nandal, Umesh Kumar; Adak, Tridibes; Bhatnagar, Raj K; Sunil, Sujatha

2014-01-01

Ookinete invasion of Anopheles midgut is a critical step for malaria transmission; the parasite numbers drop drastically and practically reach a minimum during the parasite's whole life cycle. At this stage, the parasite as well as the vector undergoes immense oxidative stress. Thereafter, the vector undergoes oxidative stress at different time points as the parasite invades its tissues during the parasite development. The present study was undertaken to reconstruct the network of differentially expressed genes involved in oxidative stress in Anopheles stephensi during Plasmodium development and maturation in the midgut. Using high throughput next generation sequencing methods, we generated the transcriptome of the An. stephensi midgut during Plasmodium vinckei petteri oocyst invasion of the midgut epithelium. Further, we utilized large datasets available on public domain on Anopheles during Plasmodium ookinete invasion and Drosophila datasets and arrived upon clusters of genes that may play a role in oxidative stress. Finally, we used support vector machines for the functional prediction of the un-annotated genes of An. stephensi. Integrating the results from all the different data analyses, we identified a total of 516 genes that were involved in oxidative stress in An. stephensi during Plasmodium development. The significantly regulated genes were further extracted from this gene cluster and used to infer an oxidative stress network of An. stephensi. Using system biology approaches, we have been able to ascertain the role of several putative genes in An. stephensi with respect to oxidative stress. Further experimental validations of these genes are underway.

Plasmodium falciparum in vitro continuous culture conditions: A comparison of parasite susceptibility and tolerance to anti-malarial drugs throughout the asexual intra-erythrocytic life cycle.

PubMed

Duffy, Sandra; Avery, Vicky M

2017-12-01

The continuous culture of Plasmodium falciparum is often seen as a means to an end, that end being to probe the biology of the parasite in question, and ultimately for many in the malaria drug discovery arena, to identify means of killing the parasite in order to treat malaria. In vitro continuous culture of Plasmodium falciparum is a fundamental requirement when undertaking malaria research where the primary objectives utilise viable parasites of a desired lifecycle stage. This investigation, and resulting data, compared the impact culturing Plasmodium falciparum long term (4 months) in different environmental conditions had on experimental outcomes and thus conclusions. The example presented here focused specifically on the effect culture conditions had on the in vitro tolerance of Plasmodium falciparum to standard anti-malarial drugs, including artemisinin and lumefantrine. Historical data from an independent experiment for 3D7-ALB (5% O 2 ) was also compared with that obtained from this study. We concluded that parasites cultured for several months in media supplemented with a serum substitute such as Albumax II ® or within hyperoxic conditions (21% O 2 ), demonstrate highly variable responses to artemisinin and lumefantrine but not all anti-malarial drugs, when compared to those cultured in human serum in combination with Albumax II ® under normoxic conditions (5% O 2 ) for the parasite. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reassessment of asymptomatic carriers of Plasmodium spp. in an endemic area with a very low incidence of malaria in extra-Amazonian Brazil.

PubMed

de Alencar, Filomena E C; Malafronte, Rosely Dos Santos; Cerutti, Crispim; Natal Fernandes, Lícia; Buery, Julyana Cerqueira; Fux, Blima; Rezende, Helder Ricas; Miranda, Angelica Espinosa

2017-11-09

Regions with residual transmission are potential obstacles to the elimination of malaria. It is, therefore, essential to understand the factors associated with the maintenance of endemic malaria in these areas. The objective was to investigate whether the status of asymptomatic carriers of Plasmodium spp. DNA is maintained in the long term in an extra-Amazonian region of Brazil with low incidence, residual malaria transmission. Asymptomatic carriers of Plasmodium DNA detected in a survey carried out between 2001 and 2004 were reassessed between 2010 and 2011 using questionnaires, PCR and thick and thin blood smear tests three times at 3-month intervals. Of the 48 carriers detected between 2001 and 2004, 37 were located. Of these, only two had positive PCR results and, as in the first survey, Plasmodium malariae DNA was detected. The findings suggest that untreated dwellers from this extra-Amazonian region, who initially harbour malaria parasites, may become negative without ever developing apparent symptoms of the disease. Although the possibility of re-infection cannot be ruled out, the finding of two individuals harbouring P. malariae, both in the first and in the second survey, may be compatible with a long-term carrier state for this parasite. Since most clinical cases of malaria in the region are a consequence of infection by Plasmodium vivax, the epidemiological impact of such long-term carriage would be limited.

Plasmodium malariae and P. ovale genomes provide insights into malaria parasite evolution

PubMed Central

Rutledge, Gavin G.; Böhme, Ulrike; Sanders, Mandy; Reid, Adam J.; Cotton, James A.; Maiga-Ascofare, Oumou; Djimdé, Abdoulaye A.; Apinjoh, Tobias O.; Amenga-Etego, Lucas; Manske, Magnus; Barnwell, John W.; Renaud, François; Ollomo, Benjamin; Prugnolle, Franck; Anstey, Nicholas M.; Auburn, Sarah; Price, Ric N.; McCarthy, James S.; Kwiatkowski, Dominic P.; Newbold, Chris I.; Berriman, Matthew; Otto, Thomas D.

2017-01-01

Elucidation of the evolutionary history and interrelatedness of Plasmodium species that infect humans has been hampered by a lack of genetic information for three human-infective species: P. malariae and two P. ovale species (P. o. curtisi and P. o. wallikeri)1. These species are prevalent across most regions in which malaria is endemic2,3 and are often undetectable by light microscopy4, rendering their study in human populations difficult5. The exact evolutionary relationship of these species to the other human-infective species has been contested6,7. Using a new reference genome for P. malariae and a manually curated draft P. o. curtisi genome, we are now able to accurately place these species within the Plasmodium phylogeny. Sequencing of a P. malariae relative that infects chimpanzees reveals similar signatures of selection in the P. malariae lineage to another Plasmodium lineage shown to be capable of colonization of both human and chimpanzee hosts. Molecular dating suggests that these host adaptations occurred over similar evolutionary timescales. In addition to the core genome that is conserved between species, differences in gene content can be linked to their specific biology. The genome suggests that P. malariae expresses a family of heterodimeric proteins on its surface that have structural similarities to a protein crucial for invasion of red blood cells. The data presented here provide insight into the evolution of the Plasmodium genus as a whole. PMID:28117441

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras

PubMed Central

2012-01-01

Background Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite’s circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Methods Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. Results and conclusion A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission. PMID:23181845

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras.

PubMed

Lopez, Ana Cecilia; Ortiz, Andres; Coello, Jorge; Sosa-Ochoa, Wilfredo; Torres, Rosa E Mejia; Banegas, Engels I; Jovel, Irina; Fontecha, Gustavo A

2012-11-26

Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite's circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

Climate, environment and transmission of malaria.

PubMed

Rossati, Antonella; Bargiacchi, Olivia; Kroumova, Vesselina; Zaramella, Marco; Caputo, Annamaria; Garavelli, Pietro Luigi

2016-06-01

Malaria, the most common parasitic disease in the world, is transmitted to the human host by mosquitoes of the genus Anopheles. The transmission of malaria requires the interaction between the host, the vector and the parasite.The four species of parasites responsible for human malaria are Plasmodium falciparum, Plasmodium ovale, Plasmodium malariae and Plasmodium vivax. Occasionally humans can be infected by several simian species, like Plasmodium knowlesi, recognised as a major cause of human malaria in South-East Asia since 2004. While P. falciparum is responsible for most malaria cases, about 8% of estimated cases globally are caused by P. vivax. The different Plasmodia are not uniformly distributed although there are areas of species overlap. The life cycle of all species of human malaria parasites is characterised by an exogenous sexual phase in which multiplication occurs in several species of Anopheles mosquitoes, and an endogenous asexual phase in the vertebrate host. The time span required for mature oocyst development in the salivary glands is quite variable (7-30 days), characteristic of each species and influenced by ambient temperature. The vector Anopheles includes 465 formally recognised species. Approximately 70 of these species have the capacity to transmit Plasmodium spp. to humans and 41 are considered as dominant vector capable of transmitting malaria. The intensity of transmission is dependent on the vectorial capacity and competence of local mosquitoes. An efficient system for malaria transmission needs strong interaction between humans, the ecosystem and infected vectors. Global warming induced by human activities has increased the risk of vector-borne diseases such as malaria. Recent decades have witnessed changes in the ecosystem and climate without precedent in human history although the emphasis in the role of temperature on the epidemiology of malaria has given way to predisposing conditions such as ecosystem changes, political instability and health policies that have reduced the funds for vector control, combined with the presence of migratory flows from endemic countries.

Development of a Novel CD4+ TCR Transgenic Line That Reveals a Dominant Role for CD8+ Dendritic Cells and CD40 Signaling in the Generation of Helper and CTL Responses to Blood-Stage Malaria.

PubMed

Fernandez-Ruiz, Daniel; Lau, Lei Shong; Ghazanfari, Nazanin; Jones, Claerwen M; Ng, Wei Yi; Davey, Gayle M; Berthold, Dorothee; Holz, Lauren; Kato, Yu; Enders, Matthias H; Bayarsaikhan, Ganchimeg; Hendriks, Sanne H; Lansink, Lianne I M; Engel, Jessica A; Soon, Megan S F; James, Kylie R; Cozijnsen, Anton; Mollard, Vanessa; Uboldi, Alessandro D; Tonkin, Christopher J; de Koning-Ward, Tania F; Gilson, Paul R; Kaisho, Tsuneyasu; Haque, Ashraful; Crabb, Brendan S; Carbone, Francis R; McFadden, Geoffrey I; Heath, William R

2017-12-15

We describe an MHC class II (I-A b )-restricted TCR transgenic mouse line that produces CD4 + T cells specific for Plasmodium species. This line, termed PbT-II, was derived from a CD4 + T cell hybridoma generated to blood-stage Plasmodium berghei ANKA (PbA). PbT-II cells responded to all Plasmodium species and stages tested so far, including rodent (PbA, P. berghei NK65, Plasmodium chabaudi AS, and Plasmodium yoelii 17XNL) and human ( Plasmodium falciparum ) blood-stage parasites as well as irradiated PbA sporozoites. PbT-II cells can provide help for generation of Ab to P. chabaudi infection and can control this otherwise lethal infection in CD40L-deficient mice. PbT-II cells can also provide help for development of CD8 + T cell-mediated experimental cerebral malaria (ECM) during PbA infection. Using PbT-II CD4 + T cells and the previously described PbT-I CD8 + T cells, we determined the dendritic cell (DC) subsets responsible for immunity to PbA blood-stage infection. CD8 + DC (a subset of XCR1 + DC) were the major APC responsible for activation of both T cell subsets, although other DC also contributed to CD4 + T cell responses. Depletion of CD8 + DC at the beginning of infection prevented ECM development and impaired both Th1 and follicular Th cell responses; in contrast, late depletion did not affect ECM. This study describes a novel and versatile tool for examining CD4 + T cell immunity during malaria and provides evidence that CD4 + T cell help, acting via CD40L signaling, can promote immunity or pathology to blood-stage malaria largely through Ag presentation by CD8 + DC. Copyright © 2017 by The American Association of Immunologists, Inc.

Prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites isolated from adult symptomatic patients in northern Uganda.

PubMed

Ocan, Moses; Bwanga, Freddie; Okeng, Alfred; Katabazi, Fred; Kigozi, Edgar; Kyobe, Samuel; Ogwal-Okeng, Jasper; Obua, Celestino

2016-08-19

In the absence of an effective vaccine, malaria treatment and eradication is still a challenge in most endemic areas globally. This is especially the case with the current reported emergence of resistance to artemisinin agents in Southeast Asia. This study therefore explored the prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites in northern Uganda. Adult patients (≥18 years) presenting to out-patients department of Lira and Gulu regional referral hospitals in northern Uganda were randomly recruited. Laboratory investigation for presence of plasmodium infection among patients was done using Plasmodium falciparum exclusive rapid diagnostic test, histidine rich protein-2 (HRP2) (Pf). Finger prick capillary blood from patients with a positive malaria test was spotted on a filter paper Whatman no. 903. The parasite DNA was extracted using chelex resin method and sequenced for mutations in K13-propeller gene using Sanger sequencing. PCR DNA sequence products were analyzed using in DNAsp 5.10.01software, data was further processed in Excel spreadsheet 2007. A total of 60 parasite DNA samples were sequenced. Polymorphisms in the K13-propeller gene were detected in four (4) of the 60 parasite DNA samples sequenced. A non-synonymous polymorphism at codon 533 previously detected in Cambodia was found in the parasite DNA samples analyzed. Polymorphisms at codon 522 (non-synonymous) and codon 509 (synonymous) were also found in the samples analyzed. The study found evidence of positive selection in the Plasmodium falciparum population in northern Uganda (Tajima's D = -1.83205; Fu and Li's D = -1.82458). Polymorphism in the K13-propeller gene previously reported in Cambodia has been found in the Ugandan Plasmodium falciparum parasites. There is need for continuous surveillance for artemisinin resistance gene markers in the country.

Lipoic Acid Metabolism of Plasmodium - A Suitable Drug Target

PubMed Central

Storm, Janet; Müller, Sylke

2012-01-01

α-Lipoic acid (6,8-thioctic acid; LA) is a vital co-factor of α-ketoacid dehydrogenase complexes and the glycine cleavage system. In recent years it was shown that biosynthesis and salvage of LA in Plasmodium are necessary for the parasites to complete their complex life cycle. LA salvage requires two lipoic acid protein ligases (LplA1 and LplA2). LplA1 is confined to the mitochondrion while LplA2 is located in both the mitochondrion and the apicoplast. LplA1 exclusively uses salvaged LA and lipoylates α-ketoglutarate dehydrogenase, branched chain α-ketoacid dehydrogenase and the H-protein of the glycine cleavage system. LplA2 cannot compensate for the loss of LplA1 function during blood stage development suggesting a specific function for LplA2 that has yet to be elucidated. LA salvage is essential for the intra-erythrocytic and liver stage development of Plasmodium and thus offers great potential for future drug or vaccine development. LA biosynthesis, comprising octanoyl-acyl carrier protein (ACP) : protein N-octanoyltransferase (LipB) and lipoate synthase (LipA), is exclusively found in the apicoplast of Plasmodium where it generates LA de novo from octanoyl-ACP, provided by the type II fatty acid biosynthesis (FAS II) pathway also present in the organelle. LA is the co-factor of the acetyltransferase subunit of the apicoplast located pyruvate dehydrogenase (PDH), which generates acetyl-CoA, feeding into FAS II. LA biosynthesis is not vital for intra-erythrocytic development of Plasmodium, but the deletion of several genes encoding components of FAS II or PDH was detrimental for liver stage development of the parasites indirectly suggesting that the same applies to LA biosynthesis. These data provide strong evidence that LA salvage and biosynthesis are vital for different stages of Plasmodium development and offer potential for drug and vaccine design against malaria. PMID:22607141

Plasmodium knowlesi Skeleton-Binding Protein 1 Localizes to the ‘Sinton and Mulligan’ Stipplings in the Cytoplasm of Monkey and Human Erythrocytes

PubMed Central

Lucky, Amuza Byaruhanga; Sakaguchi, Miako; Katakai, Yuko; Kawai, Satoru; Yahata, Kazuhide; Templeton, Thomas J.

2016-01-01

The malaria parasite, Plasmodium, exports protein products to the infected erythrocyte to introduce modifications necessary for the establishment of nutrient acquisition and surface display of host interaction ligands. Erythrocyte remodeling impacts parasite virulence and disease pathology and is well documented for the human malaria parasite Plasmodium falciparum, but has been less described for other Plasmodium species. For P. falciparum, the exported protein skeleton-binding protein 1 (PfSBP1) is involved in the trafficking of erythrocyte surface ligands and localized to membranous structures within the infected erythrocyte, termed Maurer's clefts. In this study, we analyzed SBP1 orthologs across the Plasmodium genus by BLAST analysis and conserved gene synteny, which were also recently described by de Niz et al. (2016). To evaluate the localization of an SBP1 ortholog, we utilized the zoonotic malaria parasite, Plasmodium knowlesi. Immunofluorescence assay of transgenic P. knowlesi parasites expressing epitope-tagged recombinant PkSBP1 revealed a punctate staining pattern reminiscent of Maurer's clefts, following infection of either monkey or human erythrocytes. The recombinant PkSBP1-positive puncta co-localized with Giemsa-stained structures, known as ‘Sinton and Mulligan’ stipplings. Immunoelectron microscopy also showed that recombinant PkSBP1 localizes within or on the membranous structures akin to the Maurer's clefts. The recombinant PkSBP1 expressed in P. falciparum-infected erythrocytes co-localized with PfSBP1 at the Maurer's clefts, indicating an analogous trafficking pattern. A member of the P. knowlesi 2TM protein family was also expressed and localized to membranous structures in infected monkey erythrocytes. These results suggest that the trafficking machinery and induced erythrocyte cellular structures of P. knowlesi are similar following infection of both monkey and human erythrocytes, and are conserved with P. falciparum. PMID:27732628

Plasmodium subtilisin-like protease 1 (SUB1): insights into the active-site structure, specificity and function of a pan-malaria drug target.

PubMed

Withers-Martinez, Chrislaine; Suarez, Catherine; Fulle, Simone; Kher, Samir; Penzo, Maria; Ebejer, Jean-Paul; Koussis, Kostas; Hackett, Fiona; Jirgensons, Aigars; Finn, Paul; Blackman, Michael J

2012-05-15

Release of the malaria merozoite from its host erythrocyte (egress) and invasion of a fresh cell are crucial steps in the life cycle of the malaria pathogen. Subtilisin-like protease 1 (SUB1) is a parasite serine protease implicated in both processes. In the most dangerous human malarial species, Plasmodium falciparum, SUB1 has previously been shown to have several parasite-derived substrates, proteolytic cleavage of which is important both for egress and maturation of the merozoite surface to enable invasion. Here we have used molecular modelling, existing knowledge of SUB1 substrates, and recombinant expression and characterisation of additional Plasmodium SUB1 orthologues, to examine the active site architecture and substrate specificity of P. falciparum SUB1 and its orthologues from the two other major human malaria pathogens Plasmodium vivax and Plasmodium knowlesi, as well as from the rodent malaria species, Plasmodium berghei. Our results reveal a number of unusual features of the SUB1 substrate binding cleft, including a requirement to interact with both prime and non-prime side residues of the substrate recognition motif. Cleavage of conserved parasite substrates is mediated by SUB1 in all parasite species examined, and the importance of this is supported by evidence for species-specific co-evolution of protease and substrates. Two peptidyl alpha-ketoamides based on an authentic PfSUB1 substrate inhibit all SUB1 orthologues examined, with inhibitory potency enhanced by the presence of a carboxyl moiety designed to introduce prime side interactions with the protease. Our findings demonstrate that it should be possible to develop 'pan-reactive' drug-like compounds that inhibit SUB1 in all three major human malaria pathogens, enabling production of broad-spectrum antimalarial drugs targeting SUB1. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

An ultrasensitive NanoLuc-based luminescence system for monitoring Plasmodium berghei throughout its life cycle.

PubMed

De Niz, Mariana; Stanway, Rebecca R; Wacker, Rahel; Keller, Derya; Heussler, Volker T

2016-04-21

Bioluminescence imaging is widely used for cell-based assays and animal imaging studies, both in biomedical research and drug development. Its main advantages include its high-throughput applicability, affordability, high sensitivity, operational simplicity, and quantitative outputs. In malaria research, bioluminescence has been used for drug discovery in vivo and in vitro, exploring host-pathogen interactions, and studying multiple aspects of Plasmodium biology. While the number of fluorescent proteins available for imaging has undergone a great expansion over the last two decades, enabling simultaneous visualization of multiple molecular and cellular events, expansion of available luciferases has lagged behind. The most widely used bioluminescent probe in malaria research is the Photinus pyralis firefly luciferase, followed by the more recently introduced Click-beetle and Renilla luciferases. Ultra-sensitive imaging of Plasmodium at low parasite densities has not been previously achieved. With the purpose of overcoming these challenges, a Plasmodium berghei line expressing the novel ultra-bright luciferase enzyme NanoLuc, called PbNLuc has been generated, and is presented in this work. NanoLuc shows at least 150 times brighter signal than firefly luciferase in vitro, allowing single parasite detection in mosquito, liver, and sexual and asexual blood stages. As a proof-of-concept, the PbNLuc parasites were used to image parasite development in the mosquito, liver and blood stages of infection, and to specifically explore parasite liver stage egress, and pre-patency period in vivo. PbNLuc is a suitable parasite line for sensitive imaging of the entire Plasmodium life cycle. Its sensitivity makes it a promising line to be used as a reference for drug candidate testing, as well as the characterization of mutant parasites to explore the function of parasite proteins, host-parasite interactions, and the better understanding of Plasmodium biology. Since the substrate requirements of NanoLuc are different from those of firefly luciferase, dual bioluminescence imaging for the simultaneous characterization of two lines, or two separate biological processes, is possible, as demonstrated in this work.

Quality of malaria diagnosis and molecular confirmation of Plasmodium ovale curtisi in a rural area of the southeastern region of Ethiopia.

PubMed

Díaz, Pedro Berzosa; Lozano, Patricia Mula; Rincón, Jose Manuel Ramos; García, Luz; Reyes, Francisco; Llanes, Agustín Benito

2015-09-18

Approximately 50 million people (60 %) live in malaria risk areas in Ethiopia, at altitudes below 2000 m. According to official data, 60-70 % of malaria cases are due to Plasmodium falciparum, and 40-30 % by Plasmodium vivax. The species Plasmodium ovale was detected in 2013 in the northwest of the country, being the first report of the presence of this species in Ethiopia since the 60 s. The aim of this study was to assess the diagnosis by microscopy and PCR, and demonstrate the presence of other Plasmodium species in the country. The survey was conducted in Bulbula, situated in the Rift Valley (West Arsi Province, Oromia Region). From December 2010 to October 2011, 3060 samples were collected from patients with symptoms of malaria; the diagnosis of malaria was done by microscopy and confirmation by PCR. 736 samples were positive for malaria by microscopy. After removing the 260 samples (109 positives and 151 negatives) for which it was not possible to do PCR, there were a total of 2800 samples, 1209 are used for its confirmation by PCR and quality control (627 are positives and 582 negatives by microscopy). From the 627 positive samples, 604 were confirmed as positive by PCR, 23 false positives were detected, and the group of 582 negative samples, 184 were positive by PCR (false negatives), which added to the previous positive samples is a total of 788, positive samples for some species of Plasmodium sp. 13.3 % more positives were detected with the PCR than the microscopy. Importantly, 23 samples were detected by PCR as P. ovale, after the sequencing of these samples was determined as P. ovale curtisi. The PCR detected more positive samples than the microscopy; in addition, P. ovale and P. ovale/P. vivax were detected that had not been detected by microscopy, which can affect in the infection control.

Evaluation of a rapid diagnostic test (CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test) for the diagnosis of malaria in a reference setting

PubMed Central

2010-01-01

Background Malaria Rapid Diagnostic Tests (RDTs) are widely used for diagnosing malaria. The present retrospective study evaluated the CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test targeting the Plasmodium falciparum specific antigen histidine-rich protein (HRP-2) and the pan-Plasmodium antigen lactate dehydrogenase (pLDH) in a reference setting. Methods The CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test was evaluated on a collection of samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included were P. falciparum (n = 320), Plasmodium vivax (n = 76), Plasmodium ovale (n = 76), Plasmodium malariae (n = 23) and Plasmodium negative samples (n = 95). Results Overall sensitivity for the detection of P. falciparum was 88.8%, increasing to 94.3% and 99.3% at parasite densities above 100 and 1,000/μl respectively. For P. vivax, P. ovale and P. malariae, overall sensitivities were 77.6%, 18.4% and 30.4% respectively. For P. vivax sensitivity reached 90.2% for parasite densities above 500/μl. Incorrect species identification occurred in 11/495 samples (2.2%), including 8/320 (2.5%) P. falciparum samples which generated only the pan-pLDH line. For P. falciparum samples, 205/284 (72.2%) HRP-2 test lines had strong or medium line intensities, while for all species the pan-pLDH lines were less intense, especially in the case of P. ovale. Agreement between observers was excellent (kappa values > 0.81 for positive and negative readings) and test results were reproducible. The test was easy to perform with good clearing of the background. Conclusion The CareStart™ Malaria HRP-2/pLDH (Pf/pan) Combo Test performed well for the detection of P. falciparum and P. vivax, but sensitivities for P. ovale and P. malariae were poor. PMID:20565816

Evaluation of a rapid diagnostic test (CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test) for the diagnosis of malaria in a reference setting.

PubMed

Maltha, Jessica; Gillet, Philippe; Bottieau, Emmanuel; Cnops, Lieselotte; van Esbroeck, Marjan; Jacobs, Jan

2010-06-18

Malaria Rapid Diagnostic Tests (RDTs) are widely used for diagnosing malaria. The present retrospective study evaluated the CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test targeting the Plasmodium falciparum specific antigen histidine-rich protein (HRP-2) and the pan-Plasmodium antigen lactate dehydrogenase (pLDH) in a reference setting. The CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test was evaluated on a collection of samples obtained in returned international travellers using microscopy corrected by PCR as the reference method. Included were P. falciparum (n = 320), Plasmodium vivax (n = 76), Plasmodium ovale (n = 76), Plasmodium malariae (n = 23) and Plasmodium negative samples (n = 95). Overall sensitivity for the detection of P. falciparum was 88.8%, increasing to 94.3% and 99.3% at parasite densities above 100 and 1,000/microl respectively. For P. vivax, P. ovale and P. malariae, overall sensitivities were 77.6%, 18.4% and 30.4% respectively. For P. vivax sensitivity reached 90.2% for parasite densities above 500/microl. Incorrect species identification occurred in 11/495 samples (2.2%), including 8/320 (2.5%) P. falciparum samples which generated only the pan-pLDH line. For P. falciparum samples, 205/284 (72.2%) HRP-2 test lines had strong or medium line intensities, while for all species the pan-pLDH lines were less intense, especially in the case of P. ovale. Agreement between observers was excellent (kappa values > 0.81 for positive and negative readings) and test results were reproducible. The test was easy to perform with good clearing of the background. The CareStart Malaria HRP-2/pLDH (Pf/pan) Combo Test performed well for the detection of P. falciparum and P. vivax, but sensitivities for P. ovale and P. malariae were poor.

Evaluation of the Palutop+4 malaria rapid diagnostic test in a non-endemic setting.

PubMed

van Dijk, David P J; Gillet, Philippe; Vlieghe, Erika; Cnops, Lieselotte; van Esbroeck, Marjan; Jacobs, Jan

2009-12-12

Palutop+4 (All. Diag, Strasbourg, France), a four-band malaria rapid diagnostic test (malaria RDT) targeting the histidine-rich protein 2 (HRP-2), Plasmodium vivax-specific parasite lactate dehydrogenase (Pv-pLDH) and pan Plasmodium-specific pLDH (pan-pLDH) was evaluated in a non-endemic setting on stored whole blood samples from international travellers suspected of malaria. Microscopy corrected by PCR was the reference method. Samples include those infected by Plasmodium falciparum (n = 323), Plasmodium vivax (n = 97), Plasmodium ovale (n = 73) and Plasmodium malariae (n = 25) and 95 malaria negative samples. The sensitivities for the diagnosis of P. falciparum, P. vivax, P. malariae and P. ovale were 85.1%, 66.0%, 32.0% and 5.5%. Sensitivities increased at higher parasite densities and reached 90.0% for P. falciparum >100/microl and 83.8% for P. vivax > 500/microl. Fourteen P. falciparum samples reacted with the Pv-pLDH line, one P. vivax sample with the HRP-2 line, and respectively two and four P. ovale and P. malariae samples reacted with the HRP-2 line. Two negative samples gave a signal with the HRP-2 line. Faint and weak line intensities were observed for 129/289 (44.6%) HRP-2 lines in P. falciparum samples, for 50/64 (78.1%) Pv-pLDH lines in P. vivax samples and for 9/13 (69.2%) pan-pLDH lines in P. ovale and P. malariae samples combined. Inter-observer reliabilities for positive and negative readings were excellent for the HRP-2 and Pv-pLDH lines (overall agreement > 92.0% and kappa-values for each pair of readers >or= 0.88), and good for the pan-pLDH line (85.5% overall agreement and kappa-values >or= 0.74). Palutop+4 performed moderately for the detection of P. falciparum and P. vivax, but sensitivities were lower than those of three-band malaria RDTs.

Outbreak of Avian Malaria Associated to Multiple Species of Plasmodium in Magellanic Penguins Undergoing Rehabilitation in Southern Brazil

PubMed Central

Vanstreels, Ralph Eric Thijl; Kolesnikovas, Cristiane K. M.; Sandri, Sandro; Silveira, Patrícia; Belo, Nayara O.; Ferreira Junior, Francisco C.; Epiphanio, Sabrina; Steindel, Mário; Braga, Érika M.; Catão-Dias, José Luiz

2014-01-01

Avian malaria is a mosquito-borne disease caused by Plasmodium spp. Avian plasmodia are recognized conservation-threatening pathogens due to their potential to cause severe epizootics when introduced to bird populations with which they did not co-evolve. Penguins are considered particularly susceptible, as outbreaks in captive populations will often lead to high morbidity and rapid mortality. We used a multidisciplinary approach to investigate an outbreak of avian malaria in 28 Magellanic penguins (Spheniscus magellanicus) at a rehabilitation center during summer 2009 in Florianópolis, Brazil. Hemosporidian infections were identified by microscopic and molecular characterization in 64% (18/28) of the penguins, including Plasmodium (Haemamoeba) tejerai, Plasmodium (Huffia) elongatum, a Plasmodium (Haemamoeba) sp. lineage closely related to Plasmodium cathemerium, and a Haemoproteus (Parahaemoproteus) sp. lineage closely related to Haemoproteus syrnii. P. tejerai played a predominant role in the studied outbreak and was identified in 72% (13/18) of the hemosporidian-infected penguins, and in 89% (8/9) of the penguins that died, suggesting that this is a highly pathogenic parasite for penguins; a detailed description of tissue meronts and lesions is provided. Mixed infections were identified in three penguins, and involved P. elongatum and either P. tejerai or P. (Haemamoeba) sp. that were compatible with P. tejerai but could not be confirmed. In total, 32% (9/28) penguins died over the course of 16 days despite oral treatment with chloroquine followed by sulfadiazine-trimethoprim. Hemosporidian infections were considered likely to have occurred during rehabilitation, probably from mosquitoes infected while feeding on local native birds, whereas penguin-mosquito-penguin transmission may have played a role in later stages of the outbreak. Considering the seasonality of the infection, rehabilitation centers would benefit from narrowing their efforts to prevent avian malaria outbreaks to the penguins that are maintained throughout summer. PMID:24736326

Detection of mixed infection level of Plasmodium falciparum and Plasmodium vivax by SYBR Green I-based real-time PCR in North Gondar, north-west Ethiopia.

PubMed

Tajebe, Addimas; Magoma, Gabriel; Aemero, Mulugeta; Kimani, Francis

2014-10-18

Malaria is caused by five Plasmodium species and transmitted by anopheline mosquitoes. It occurs in single and mixed infections. Mixed infection easily leads to misdiagnosis. Accurate detection of malaria species is vital. Therefore, the study was conducted to determine the level of mixed infection and misdiagnosis of malaria species in the study area using SYBR Green I-based real time PCR. The study was conducted in seven health centres from North Gondar, north-west Ethiopia. The data of all febrile patients, who attended the outpatient department for malaria diagnosis, from October to December 2013, was recorded. Dried blood spots were prepared from 168 positive samples for molecular re-evaluation. Parasite DNA was extracted using a commercial kit and Plasmodium species were re-evaluated with SYBR Green I-based real time PCR to detect mixed infections and misdiagnosed mono-infections. Among 7343 patients who were diagnosed for malaria in six study sites within the second quarter of the Ethiopian fiscal year (2013) 1802 (24.54%) were positive for malaria parasite. Out of this, 1,216 (67.48%) Plasmodium falciparum, 553 (30.68%) Plasmodium vivax and 33 (1.8%) mixed infections of both species were recorded. The result showed high prevalence of P. falciparum and P. vivax, but very low prevalence of mixed infections. Among 168 samples collected on dried blood spot 7 (4.17%) were P. vivax, 158 (94.05%) were P. falciparum and 3 (1.80%) were mixed infections of both species. After re-evaluation 10 (5.95%) P. vivax, 112 (66.67%) P. falciparum, 21 (12.50%) P. falciparum + P. vivax mixed infection, and 17 (10.12%) Plasmodium ovale positive rate was recorded. The re-evaluation showed high level of mixed infection, and misdiagnosis of P. ovale and P. vivax. The result shows that P. falciparum prevalence is higher than P. vivax in the study area. The results, obtained from SYBR Green I-based real time PCR, indicated that the diagnosis efficiency of microscopy is very low for species-specific and mixed infection detection. Therefore, real time PCR-based species diagnosis should be applied for clinical diagnosis and quality control purposes in order to prevent the advent of drug resistant strains due to misdiagnosis and mistreatment.

Patterns of mixed Plasmodium species infections among children six years and under in selected malaria hyper-endemic communities of Zambia: population-based survey observations.

PubMed

Sitali, Lungowe; Chipeta, James; Miller, John M; Moonga, Hawela B; Kumar, Nirbhay; Moss, William J; Michelo, Charles

2015-05-02

Although malaria is preventable and treatable, it still claims 660,000 lives every year globally with children under five years of age having the highest burden. In Zambia, malaria rapid diagnostic tests (RDTs) that only detect Plasmodium falciparum are the main confirmatory means for malaria diagnosis in most health facilities without microscopy services. As a consequence of this P. falciparum species diagnostic approach, non-falciparum malaria is not only under-diagnosed but entirely missed, thereby making the exact disease burden unknown. We thus investigated the prevalence of various Plasmodium spp. and associated burden of infection in selected communities in Zambia. Data from two malaria hyper-endemic provinces (Eastern and Luapula) of the 2012 National Malaria Indicator Survey (MIS), conducted between April and May 2012, were used. The MIS is a nationally representative, two-stage cluster survey conducted to coincide with the end of the malaria transmission season. Social, behavioural and background information were collected from households as part of the survey. Thick blood smears, RDTs and dried blood spots (DBS) were collected from children below six years of age. Slides were stained using Giemsa and examined by microscopy while polymerase chain reaction (PCR) was used to analyse the DBS for malaria Plasmodium spp. Multivariate logistic regression was employed to examine the association between background factors and malaria. Overall, 873 children younger than six years of age were surveyed. The overall prevalence of Plasmodium spp. by PCR was 54.3% (95% CI 51-57.6%). Of the total Plasmodium isolates, 88% were P. falciparum, 10.6% were mixed infections and 1.4% were non-falciparum mono infections. Among the mixed infections, the majority were a combination of P. falciparum and P. malariae (6.5% of all mixed infections). Children two years and older (2-5 years) had three-fold higher risk of mixed malaria infections (aOR 2.8 CI 1.31-5.69) than children younger than two years of age. The high prevalence of mixed Plasmodium spp. infections in this population stresses review of the current malaria RDT diagnostic approaches. The observed less incidence of mixed infections in children under two years of age compared to their older two-to-five-year-old counterparts is probably due to the protective maternal passive immunity, among other factors, in that age group.

Molecular characterization of misidentified Plasmodium ovale imported cases in Singapore.

PubMed

Chavatte, Jean-Marc; Tan, Sarah Bee Hui; Snounou, Georges; Lin, Raymond Tzer Pin Valentine

2015-11-14

Plasmodium ovale, considered the rarest of the malaria parasites of humans, consists of two morphologically identical but genetically distinct sympatric species, Plasmodium ovale curtisi and Plasmodium ovale wallikeri. These parasites resemble morphologically to Plasmodium vivax with which they also share a tertian periodicity and the ability to cause relapses, making them easily misidentified as P. vivax. Plasmodium ovale infections are rarely reported, but given the likelihood of misidentification, their prevalence might be underestimated. Morphological and molecular analysis of confirmed malaria cases admitted in Singapore in 2012-2014 detected nine imported P. ovale cases that had been misidentified as P. vivax. Since P. ovale had not been previously officially reported in Singapore, a retrospective analysis of available, frozen, archival blood samples was performed and returned two additional misidentified P. ovale cases in 2003 and 2006. These eleven P. ovale samples were characterized with respect to seven molecular markers (ssrRNA, Potra, Porbp2, Pog3p, dhfr-ts, cytb, cox1) used in recent studies to distinguish between the two sympatric species, and to a further three genes (tufa, clpC and asl). The morphological features of P. ovale and the differential diagnosis with P. vivax were reviewed and illustrated by microphotographs. The genetic dimorphism between P. ovale curtisi and P. ovale wallikeri was assessed by ten molecular markers distributed across the three genomes of the parasite (Genbank KP050361-KP050470). The data obtained for seven of these markers were compared with those published and confirmed that both P. ovale species were present. This dimorphism was also confirmed for the first time on: (1) two genes from the apicoplast genome (tufA and clpC genes); and, (2) the asl gene that was used for phylogenetic analyses of other Plasmodium species, and that was found to harbour the highest number of dimorphic loci between the two P. ovale species. Misidentified P. ovale infections are reported for the first time among imported malaria cases in Singapore. Genetic dimorphism between P. ovale curtisi and P. ovale wallikeri was confirmed using markers from the parasites' three genomes. The apparent increase of imported P. ovale since 2012 (with yearly detection of cases) is puzzling. Given decrease in the overall number of malaria cases recorded in Singapore since 2010 the 'resurgence' of this neglected species raises public health concerns.

Prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang à Kisangani, République Démocratique du Congo

PubMed Central

Bassandja, Jacques Ossinga; Agasa, Salomon Batina; Likwela, Joris Losimba

2014-01-01

Introduction Le paludisme transfusionnel est une réalité en Afrique Sub-saharienne, en raison des transfusions sanguines répétées, peu ou non contrôlées et où les donneurs sont en majorité potentiellement porteurs d'hématozoaires. L'objectif de cette étude était de déterminer la prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang à Kisangani. Méthodes Une étude transversale a été menée au Centre Provincial de Transfusion Sanguine à Kisangani du 1er Décembre 2012 au 31 Mars 2013 et a concerné 480 donneurs bénévoles de sang. Résultats La prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang était de 28,3%. Plasmodium falciparum était l'espèce la plus répandue (96,3%). Près de la moitié des donneurs avait une parasitémie supérieure à 2000 parasites/µl. Les facteurs qui étaient significativement associés à la parasitémie étaient le jeune âge, le 1er don, et la non utilisation de la moustiquaire imprégnée d'insecticide à longue durée (MILD). Conclusion Les résultats de cette étude montrent que la prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang était élevée, constituant ainsi un risque important de transmission du parasite aux receveurs souvent en mauvais état général. Cependant, l'utilisation de la MILD et la fidélisation des donneurs bénévoles semblent constituer des moyens utiles de réduction du risque de portage asymptomatique du Plasmodium. Une sensibilisation et éventuellement des distributions ciblées de MILD aux donneurs, en particuliers les plus jeunes, pourraient réduire considérablement le portage du Plasmodium parmi les donneurs de sang et ainsi réduire le risque de paludisme transfusionnel. PMID:25328616

Detection of Plasmodium knowlesi, Plasmodium falciparum and Plasmodium vivax using loop-mediated isothermal amplification (LAMP) in a co-endemic area in Malaysia.

PubMed

Piera, Kim A; Aziz, Ammar; William, Timothy; Bell, David; González, Iveth J; Barber, Bridget E; Anstey, Nicholas M; Grigg, Matthew J

2017-01-13

Plasmodium knowlesi is the most common cause of malaria in Malaysia. However, microscopic diagnosis is inaccurate and rapid diagnostic tests (RDTs) are insufficiently sensitive. PCR is sensitive and specific but not feasible at a district level. Loop-mediated isothermal amplification (LAMP) shows potential with only basic requirements. A commercially available LAMP assay, the Eiken Loopamp™ MALARIA Pan Detection kit, is sensitive for Plasmodium falciparum and Plasmodium vivax, but has not previously been evaluated for P. knowlesi. This study aims to determine the sensitivity of this LAMP assay for detecting P. knowlesi infection. Study participants included 73 uncomplicated malaria patients with PCR species confirmation: 50 P. knowlesi, 20 P. falciparum and 3 P. vivax. Nineteen malaria-negative, non-endemic area controls were also included. The sensitivity of the Eiken Loopamp™ MALARIA Pan Detection kit (Pan LAMP) for detecting each Plasmodium species was evaluated. Sensitivity and specificity of the Eiken Loopamp™ MALARIA Pf Detection kit (Pf LAMP) for P. falciparum were also determined. The limit of detection for each LAMP assay was evaluated, with results compared to PCR. All P. knowlesi patients were also tested by CareStart™ (Pf/VOM) and OptiMAL-IT™ (Pan/Pf) RDTs. The sensitivity of the Pan LAMP assay was 100% for P. knowlesi (95% CI 92.9-100), P. falciparum (95% CI 83.2-100), and P. vivax (95% CI 29.2-100). The Pf LAMP was 100% sensitive and specific for P. falciparum detection, with all P. knowlesi samples having a negative reaction. LAMP sensitivity was superior to both RDTs, with only 10 and 28% of P. knowlesi samples testing positive to CareStart™ and OptiMAL-IT™, respectively. Limit of detection using the Pan LAMP for both P. knowlesi and P. vivax was 2 parasites/μL, comparable to PCR. For P. falciparum both the Pan LAMP and Pf LAMP demonstrated a limit of detection of 20 parasites/μL. The Eiken Loopamp™ MALARIA Pan Detection kit is sensitive for detection of P. knowlesi in low parasitaemia clinical infections, as well as P. falciparum and P. vivax. However, a P. knowlesi-specific field assay in a simpler format would assist correct species identification and initiation of optimal treatment for all malaria patients.

Correction to: Polymorphisms in chloroquine resistance-associated genes in Plasmodium vivax in Ethiopia.

PubMed

Golassa, Lemu; Erko, Berhanu; Baliraine, Frederick N; Aseffa, Abraham; Swedberg, Göte

2018-05-02

After publication of the original article [1], it came to the authors' attention that the primers mentioned in Table 1 for the amplification of the pvcrt-o gene of Plasmodium vivax are not the ones actually used for the experiments. The correct primers and PCR product size are as below.

Piperaquine Resistance in Plasmodium falciparum, West Africa.

PubMed

Inoue, Juliana; Silva, Miguel; Fofana, Bakary; Sanogo, Kassim; Mårtensson, Andreas; Sagara, Issaka; Björkman, Anders; Veiga, Maria Isabel; Ferreira, Pedro Eduardo; Djimde, Abdoulaye; Gil, José Pedro

2018-08-17

Dihydroartemisinin/piperaquine (DHA/PPQ) is increasingly deployed as antimalaria drug in Africa. We report the detection in Mali of Plasmodium falciparum infections carrying plasmepsin 2 duplications (associated with piperaquine resistance) in 7/65 recurrent infections within 2 months after DHA/PPQ treatment. These findings raise concerns about the long-term efficacy of DHA/PPQ treatment in Africa.

Molecular detection of Plasmodium knowlesi in a Dutch traveler by real-time PCR.

PubMed

Link, Lonneke; Bart, Aldert; Verhaar, Nienke; van Gool, Tom; Pronk, Marjolijn; Scharnhorst, Volkher

2012-07-01

Plasmodium knowlesi infection with low parasitemia presents a diagnostic challenge, as rapid diagnostic tests are often negative and identification to the species level by microscopy is difficult. P. knowlesi malaria in a traveler is described, and real-time PCR is demonstrated to support fast and reliable diagnosis and identification to the species level.

A Feast of Malaria Parasite Genomes.

PubMed

Carlton, Jane M; Sullivan, Steven A

2017-03-08

The Plasmodium genus has evolved over time and across hosts, complexifying our understanding of malaria. In a recent Nature paper, Rutledge et al. (2017) describe the genome sequences of three major human malaria parasite species, providing insight into Plasmodium evolution and raising the question of how many species there are. Copyright © 2017 Elsevier Inc. All rights reserved.

Studies on the effects of sida acuta and vetiveria zizanioides against the malarial vector, anopheles stephensi and malarial parasite, plasmodium berghei

USDA-ARS?s Scientific Manuscript database

Methanolic extracts of Sida acuta and Vetiveria zizanioides leaves and root were studied for toxicity to Anopheles stephensi mosquitoes and to the malaria parasite Plasmodium berghei in mice. The extracts reduced parasitemia levels in mice by 17-69%, depending on extract concentration. Median le...

Cinnamic acid/chloroquinoline conjugates as potent agents against chloroquine-resistant Plasmodium falciparum.

PubMed

Pérez, Bianca; Teixeira, Cátia; Gut, Jiri; Rosenthal, Philip J; Gomes, José R B; Gomes, Paula

2012-09-01

Cinnamic acid derivatives containing a 4-amino-7-chloroquinoline scaffold (blue) and substituted cinnamoyl building blocks (green) linked through an alkylamine chain (red) were found to have potent (11-59 nM) in vitro activities against erythrocytic chloroquine- resistant Plasmodium falciparum. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasmodium ovale Malaria Acquired in Central Spain

PubMed Central

Calvente, Maria José; Benito, Agustin; Arévalo, Juan; Calero, Maria Angeles; Segura, Javier; Rubio, Jose Miguel

2002-01-01

We describe a case of locally acquired Plasmodium ovale malaria in Spain. The patient was a Spanish woman who had never traveled out of Spain and had no other risk factors for malaria. Because patients with malaria may never have visited endemic areas, occasional transmission of malaria to European hosts is a diagnostic and clinical challenge. PMID:12498674

Prevalence and Level of Antibodies Anti-Plasmodium spp. in Travellers with Clinical History of Imported Malaria

PubMed Central

Medina Costa, Rita; de Sousa, Karina Pires; Atouguia, Jorge; Tavira, Luis Távora; Silva, Marcelo Sousa

2013-01-01

In this study, we show that 40.29% of travellers with a possible history of malaria exposure were positive for anti-Plasmodium spp. antibodies, while these individuals were negative by microscopy. The antibody test described here is useful to elucidate malaria exposure in microscopy-negative travellers from endemic countries. PMID:23691274

Therapeutic and Transmission-Blocking 
Efficacy of Dihydroartemisinin/Piperaquine and Chloroquine against Plasmodium vivax Malaria, Cambodia.

PubMed

Popovici, Jean; Vantaux, Amelie; Primault, Lyse; Samreth, Reingsey; Piv, Eak Por; Bin, Sophalai; Kim, Saorin; Lek, Dysoley; Serre, David; Menard, Didier

2018-08-17

We assessed the efficacy of standard 3-day courses of chloroquine and dihydroartemisinin/piperaquine against Plasmodium vivax malaria. Compared with chloroquine, dihydroartemisinin/piperaquine was faster in clearing asexual P. vivax parasites and blocking human-to-mosquito transmission. This drug combination was also more effective in preventing potential recurrences for >2 months.

Finding the sweet spots of inhibition: understanding the targets of a functional antibody against Plasmodium vivax Duffy binding protein

PubMed Central

Ntumngia, Francis B.; King, Christopher L.; Adams, John H.

2014-01-01

Plasmodium vivax Duffy binding protein region II (DBPII) is an essential ligand for reticulocyte invasion, thereby making this molecule an attractive vaccine candidate against asexual blood-stage P. vivax. Similar to other Plasmodium blood-stage vaccine candidates, strain-specific immunity due to DBPII allelic variation may complicate vaccine efficacy. Targeting immune responses to more conserved epitopes that are potential targets of strain-transcending neutralizing immunity is necessary to avoid induction of strain-specific responses to dominant variant epitopes. In this article, we focus on different approaches to optimize the design of DBP immunogenicity to target conserved epitopes, which is important for developing a broadly effective vaccine against P. vivax. PMID:23068913

The Treatment of Plasmodium knowlesi Malaria.

PubMed

Barber, Bridget E; Grigg, Matthew J; William, Timothy; Yeo, Tsin W; Anstey, Nicholas M

2017-03-01

Plasmodium knowlesi occurs across Southeast Asia and is the most common cause of malaria in Malaysia. High parasitaemias can develop rapidly, and the risk of severe disease in adults is at least as high as in falciparum malaria. Prompt initiation of effective treatment is therefore essential. Intravenous artesunate is highly effective in severe knowlesi malaria and in those with moderately high parasitaemia but otherwise uncomplicated disease. Both chloroquine and artemisinin-combination therapy (ACT) are highly effective for uncomplicated knowlesi malaria, with faster parasite clearance times and lower anaemia rates with ACT. Given the difficulties with microscope diagnosis of P. knowlesi, a unified treatment strategy of ACT for all Plasmodium species is recommended in coendemic regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Drug Discovery and Development of Antimalarial Agents: Recent Advances.

PubMed

Thota, Sreekanth; Yerra, Rajeshwar

2016-01-01

Malaria, a deadly infectious parasitic disease, is a major issue of public health in the world today and already produces serious economic constraints in the endemic countries. Most of the malarial infections and deaths are due to Plasmodium falciparum and Plasmodium vivax species. The recent emergence of resistance necessitates the search for new antimalarial drugs, which overcome the resistance and act through new mechanisms. Although much effort has been directed towards the discovery of novel antimalarial drugs. 4-anilino quinolone triazines as potent antimalarial agents, their in silico modelling and bioevaluation as Plasmodium falciparum transketolase and β-hematin inhibitors has been reported. This review is primarily focused on the drug discovery of the recent advances in the development of antimalarial agents and their mechanism of action.

Depletion of Plasmodium berghei plasmoredoxin reveals a non-essential role for life cycle progression of the malaria parasite.

PubMed

Buchholz, Kathrin; Rahlfs, Stefan; Schirmer, R Heiner; Becker, Katja; Matuschewski, Kai

2008-06-25

Proliferation of the pathogenic Plasmodium asexual blood stages in host erythrocytes requires an exquisite capacity to protect the malaria parasite against oxidative stress. This function is achieved by a complex antioxidant defence system composed of redox-active proteins and low MW antioxidants. Here, we disrupted the P. berghei plasmoredoxin gene that encodes a parasite-specific 22 kDa member of the thioredoxin superfamily. The successful generation of plasmoredoxin knockout mutants in the rodent model malaria parasite and phenotypic analysis during life cycle progression revealed a non-vital role in vivo. Our findings suggest that plasmoredoxin fulfils a specialized and dispensable role for Plasmodium and highlights the need for target validation to inform drug development strategies.

Non-specific Patterns of Vector, Host, and Avian Malaria Parasite Associations in a Central African Rainforest

PubMed Central

Njabo, Kevin Y; Cornel, Anthony J.; Bonneaud, Camille; Toffelmier, Erin; Sehgal, R.N.M.; Valkiūnas, Gediminas; Russell, Andrew F.; Smith, Thomas B.

2010-01-01

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Here we applied high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. In all, 3134 mosquitoes representing 27 species were screened. Mosquitoes belonging to four genera (Aedes, Coquillettidia, Culex, and Mansonia) were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Occurrence of parasite lineages differed significantly among genera, as well as their probability of being infected with malaria across species and sites. Approximately one-third of these lineages were previously detected in other avian host species from the region, indicating that vertebrate host sharing is a common feature and that avian Plasmodium spp. vector breadth does not always accompany vertebrate-host breadth. This study suggests extensive invertebrate host shifts in mosquito-parasite interactions and that avian Plasmodium species are most likely not tightly coevolved with vector species. PMID:21134011

Knockout of the Rodent Malaria Parasite Chitinase PbCHT1 Reduces Infectivity to Mosquitoes

PubMed Central

Dessens, Johannes T.; Mendoza, Jacqui; Claudianos, Charles; Vinetz, Joseph M.; Khater, Emad; Hassard, Stuart; Ranawaka, Gaya R.; Sinden, Robert E.

2001-01-01

During mosquito transmission, malaria ookinetes must cross a chitin-containing structure known as the peritrophic matrix (PM), which surrounds the infected blood meal in the mosquito midgut. In turn, ookinetes produce multiple chitinase activities presumably aimed at disrupting this physical barrier to allow ookinete invasion of the midgut epithelium. Plasmodium chitinase activities are demonstrated targets for human and avian malaria transmission blockade with the chitinase inhibitor allosamidin. Here, we identify and characterize the first chitinase gene of a rodent malaria parasite, Plasmodium berghei. We show that the gene, named PbCHT1, is a structural ortholog of PgCHT1 of the avian malaria parasite Plasmodium gallinaceum and a paralog of PfCHT1 of the human malaria parasite Plasmodium falciparum. Targeted disruption of PbCHT1 reduced parasite infectivity in Anopheles stephensi mosquitoes by up to 90%. Reductions in infectivity were also observed in ookinete feeds—an artificial situation where midgut invasion occurs before PM formation—suggesting that PbCHT1 plays a role other than PM disruption. PbCHT1 null mutants had no residual ookinete-derived chitinase activity in vitro, suggesting that P. berghei ookinetes express only one chitinase gene. Moreover, PbCHT1 activity appeared insensitive to allosamidin inhibition, an observation that raises questions about the use of allosamidin and components like it as potential malaria transmission-blocking drugs. Taken together, these findings suggest a fundamental divergence among rodent, avian, and human malaria parasite chitinases, with implications for the evolution of Plasmodium-mosquito interactions. PMID:11349074

[Malaria in the Americas].

PubMed

Carme, B; Venturin, C

1999-01-01

In 1996, malaria involving Plasmodium vivax, Plasmodium falciparum, and, to a lesser extent, Plasmodium malariae was endemic in 21 countries in the Americas. The Amazon river basin and bordering areas including the Guyanas were the most affected zones. Until the mid 1970s, endemic malaria appeared to be under control. However in the ensuing 15 year period, the situation deteriorated drastically. Although trends varied depending on location, aggregate indexes indicated a twofold increase with recrudescence in previously settled areas and emergence in newly populated zones. Since 1990, the situation has worsened further in some areas where increased incidences have been associated with a high levels of drug-resistant Plasmodium falciparum. However this species remains in minority except in the Guyanas where the highest annual incidences (100 to 500 cases per 1000) and the most drug-resistant Plasmodium have been reported. The causes underlying this deterioration are numerous and complex. In regions naturally prone to transmission of the disease, outbreaks have been intensified by unrestrained settlement. The resulting deforestation has created new breeding areas for Anopheles darlingi, the main vector of malaria in the Americas. Migration of poor populations to newly opened farming and mining areas has created highly exposed areas for malaria infection. Implementation of adequate medical care and prevention measures has been hindered by a lack of money and sociopolitical unrest. Climatic phenomenon related the El Nino have also been favorable to the return of malaria to the region. Except with regard to financial resources and political unrest, the same risk factors for malaria are present in French Guiana.

Monitoring of Plasmodium infection in humans and potential vectors of malaria in a newly emerged focus in southern Iran

PubMed Central

Kalantari, Mohsen; Soltani, Zahra; Ebrahimi, Mostafa; Yousefi, Masoud; Amin, Masoumeh; Shafiei, Ayda; Azizi, Kourosh

2017-01-01

Despite control programs, which aim to eliminate malaria from Iran by 2025, transmission of malaria has not been removed from the country. This study aimed to monitor malaria from asymptomatic parasitaemia and clinical cases from about one year of active case surveillance and potential vectors of malaria in the newly emerged focus of Mamasani and Rostam, southern Iran during 2014–2015. Samples were collected and their DNAs were extracted for Polymerase Chain Reaction (PCR) assay using specific primers for detection of Plasmodium species. The Annual Parasite Incidence rate (API) was three cases per 1,000 population from 2,000 individuals in three villages. Parasites species were detected in 9 out of the 4,000 blood smear samples among which, 6 cases were indigenous and had no history of travels to endemic areas of malaria. Also, the prevalence rate of asymptomatic parasites was about 0.3%. Overall, 1073 Anopheles spp. were caught from 9 villages. Totally, 512 female samples were checked by PCR, which indicated that none of them was infected with Plasmodium. Despite new malaria local transmission in humans in Mamasani and Rostam districts, no infection with Plasmodium was observed in Anopheles species. Because of neighboring of the studied area to the re-emerged focus in Fars province (Kazerun) and important endemic foci of malaria in other southern provinces, such as Hormozgan and Kerman, monitoring of the vectors and reservoir hosts of Plasmodium species would be unavoidable. Application of molecular methods, such as PCR, can simplify access to the highest level of accuracy in malaria researches. PMID:28078947

Rediscovery and redescription of Plasmodium pifanoi and description of two additional Plasmodium parasites of Venezuelan lizards.

PubMed

Telford, Sam R; Telford, Sam R

2003-04-01

Plasmodium pifanoi Scorza and Dagert B., known only from the type host, Ameiva ameiva, is redescribed from Kentropyx calcarata collected in Territorio Amazonas, Venezuela. Schizonts, 6.2 x 4.5 (4-8 x 3-6), produce on average 11.9 (7-16) merozoites. Gametocytes average 12.4 x 6.0 (8-16 x 4-10), with length x width (LW) 72.9 (52-112) and L/W 2.18 (1.1-3.3), and always contain 1-5 prominent vacuoles. Macrogametocytes in active infection are longer than microgametocytes, with greater LW, but gametocytes in chronic infection are not sexually dimorphic in dimension and are slightly smaller. Two additional malarial parasites are described from K. calcarata. Plasmodium lepidoptiformis has small schizonts, 4.6 x 3.2 (3-6 x 2.5-3), that produce 5.1 (4-8) merozoites and commonly resemble a butterfly in appearance. Gametocytes are elongate, 9.0 x 4.3 (7-10 x 3-6), with LW 38.3 (24-51) and L/W 2.2 (1.3-3.3), and sexually dimorphic, with macrogametocytes longer than microgametocytes, with greater LW. Plasmodium minasense calcaratae is characterized by very small, usually fan-shaped, schizonts. 3.4 x 2.6 (2.5-4.5 x 2.0-3.0), that produce 3.9 (3-4) merozoites. Gametocytes are spherical or ovoid, 6.7 x 5.0 (4.5-9.0 x 3.0-7.0), with LW 33.7 (15-54) and L/W 1.4 (1.0-2.3), with no sexual dimorphism in dimensions.

Application of in-situ hybridization for the detection and identification of avian malaria parasites in paraffin wax-embedded tissues from captive penguins

PubMed Central

Dinhopl, Nora; Mostegl, Meike M.; Richter, Barbara; Nedorost, Nora; Maderner, Anton; Fragner, Karin; Weissenböck, Herbert

2011-01-01

In captive penguins, avian malaria due to Plasmodium parasites is a well-recognized disease problem as these protozoa may cause severe losses among valuable collections of zoo birds. In blood films from naturally infected birds, identification and differentiation of malaria parasites based on morphological criteria are difficult because parasitaemia is frequently light and blood stages, which are necessary for identification of parasites, are often absent. Post-mortem diagnosis by histological examination of tissue samples is sometimes inconclusive due to the difficulties in differentiating protozoal tissue stages from fragmented nuclei in necrotic tissue. The diagnosis of avian malaria would be facilitated by a technique with the ability to specifically identify developmental stages of Plasmodium in tissue samples. Thus, a chromogenic in-situ hybridization (ISH) procedure with a digoxigenin-labelled probe, targeting a fragment of the 18S rRNA, was developed for the detection of Plasmodium parasites in paraffin wax-embedded tissues. This method was validated in comparison with traditional techniques (histology, polymerase chain reaction), on various tissues from 48 captive penguins that died at the zoological garden Schönbrunn, Vienna, Austria. Meronts of Plasmodium gave clear signals and were easily identified using ISH. Potential cross-reactivity of the probe was ruled out by the negative outcome of the ISH against a number of protozoa and fungi. Thus, ISH proved to be a powerful, specific and sensitive tool for unambiguous detection of Plasmodium parasites in paraffin wax-embedded tissue samples. PMID:21711191

The adenosine deaminases of Plasmodium vivax and Plasmodium falciparum exhibit surprising differences in ligand specificity

PubMed Central

Ivanov, Andrei A.; Matsumura, Ichiro

2012-01-01

Plasmodium vivax and P. falciparum cause malaria, so proteins essential for their survival in vivo are potential anti-malarial drug targets. Adenosine deaminases (ADA) catalyze the irreversible conversion of adenosine into inosine, and play a critical role in the purine salvage pathways of Plasmodia and their mammalian hosts. Currently, the number of selective inhibitors of Plasmodium ADAs is limited. One potent and widely used inhibitor of the human ADA (hADA), erythro-9-(2-hydroxy-3-nonly)adenine (EHNA), is a very weak inhibitor (Ki = 120uM) of P. falciparum ADA (pfADA). EHNA-like compounds are thus excluded from consideration as potential inhibitors of Plasmodium ADA in general. However, EHNA activity in P. vivax ADA (pvADA) has not been reported. Here we applied computational molecular modeling to identify the mechanisms of the ligand recognition unique for P. vivax and P. falciparum ADA. Based on the computational studies, we performed molecular biology experiments to show that EHNA is at least 60-fold more potent against pvADA (Ki = 1.9uM) than against pfADA. The D172A pvADA mutant is bound even more tightly (Ki = 0.9uM). These results improve our understanding of the mechanisms of ADA ligand recognition and species-selectivity, and facilitate the rational design of novel EHNA-based ADA inhibitors as anti-malarial drugs. To demonstrate a practical application of our findings we have computationally predicted a novel potential inhibitor of pvADA selective versus the human ADA. PMID:22481078

Acute respiratory distress syndrome and acute renal failure from Plasmodium ovale infection with fatal outcome

PubMed Central

2013-01-01

Background Plasmodium ovale is one of the causative agents of human malaria. Plasmodium ovale infection has long been thought to be non-fatal. Due to its lower morbidity, P. ovale receives little attention in malaria research. Methods Two Malaysians went to Nigeria for two weeks. After returning to Malaysia, they fell sick and were admitted to different hospitals. Plasmodium ovale parasites were identified from blood smears of these patients. The species identification was further confirmed with nested PCR. One of them was successfully treated with no incident of relapse within 12-month medical follow-up. The other patient came down with malaria-induced respiratory complication during the course of treatment. Although parasites were cleared off the circulation, the patient’s condition worsened. He succumbed to multiple complications including acute respiratory distress syndrome and acute renal failure. Results Sequencing of the malaria parasite DNA from both cases, followed by multiple sequence alignment and phylogenetic tree construction suggested that the causative agent for both malaria cases was P. ovale curtisi. Discussion In this report, the differences between both cases were discussed, and the potential capability of P. ovale in causing severe complications and death as seen in this case report was highlighted. Conclusion Plasmodium ovale is potentially capable of causing severe complications, if not death. Complete travel and clinical history of malaria patient are vital for successful diagnoses and treatment. Monitoring of respiratory and renal function of malaria patients, regardless of the species of malaria parasites involved is crucial during the course of hospital admission. PMID:24180319

Host-mediated impairment of parasite maturation during blood-stage Plasmodium infection

PubMed Central

Khoury, David S.; Cromer, Deborah; Akter, Jasmin; Sebina, Ismail; Elliott, Trish; Thomas, Bryce S.; Soon, Megan S. F.; James, Kylie R.; Best, Shannon E.; Haque, Ashraful; Davenport, Miles P.

2017-01-01

Severe malaria and associated high parasite burdens occur more frequently in humans lacking robust adaptive immunity to Plasmodium falciparum. Nevertheless, the host may partly control blood-stage parasite numbers while adaptive immunity is gradually established. Parasite control has typically been attributed to enhanced removal of parasites by the host, although in vivo quantification of this phenomenon remains challenging. We used a unique in vivo approach to determine the fate of a single cohort of semisynchronous, Plasmodium berghei ANKA- or Plasmodium yoelii 17XNL-parasitized red blood cells (pRBCs) after transfusion into naive or acutely infected mice. As previously shown, acutely infected mice, with ongoing splenic and systemic inflammatory responses, controlled parasite population growth more effectively than naive controls. Surprisingly, however, this was not associated with accelerated removal of pRBCs from circulation. Instead, transfused pRBCs remained in circulation longer in acutely infected mice. Flow cytometric assessment and mathematical modeling of intraerythrocytic parasite development revealed an unexpected and substantial slowing of parasite maturation in acutely infected mice, extending the life cycle from 24 h to 40 h. Importantly, impaired parasite maturation was the major contributor to control of parasite growth in acutely infected mice. Moreover, by performing the same experiments in rag1−/− mice, which lack T and B cells and mount weak inflammatory responses, we revealed that impaired parasite maturation is largely dependent upon the host response to infection. Thus, impairment of parasite maturation represents a host-mediated, immune system-dependent mechanism for limiting parasite population growth during the early stages of an acute blood-stage Plasmodium infection. PMID:28673996

A Novel Methodology for Bioenergetic Analysis of Plasmodium falciparum Reveals a Glucose-Regulated Metabolic Shift and Enables Mode of Action Analyses of Mitochondrial Inhibitors.

PubMed

Sakata-Kato, Tomoyo; Wirth, Dyann F

2016-12-09

Given that resistance to all drugs in clinical use has arisen, discovery of new antimalarial drug targets is eagerly anticipated. The Plasmodium mitochondrion has been considered a promising drug target largely based on its significant divergence from the host organelle as well as its involvement in ATP production and pyrimidine biosynthesis. However, the functions of Plasmodium mitochondrial protein complexes and associated metabolic pathways are not fully characterized. Here, we report the development of novel and robust bioenergetic assay protocols for Plasmodium falciparum asexual parasites utilizing a Seahorse Bioscience XFe24 Extracellular Flux Analyzer. These protocols allowed us to simultaneously assess the direct effects of metabolites and inhibitors on mitochondrial respiration and glycolytic activity in real-time with the readout of oxygen consumption rate and extracellular acidification rate. Using saponin-freed parasites at the schizont stage, we found that succinate, malate, glycerol-3-phosphate, and glutamate, but not pyruvate, were able to increase the oxygen consumption rate and that glycerol-3-phosphate dehydrogenase had the largest potential as an electron donor among tested mitochondrial dehydrogenases. Furthermore, we revealed the presence of a glucose-regulated metabolic shift between oxidative phosphorylation and glycolysis. We measured proton leak and reserve capacity and found bioenergetic evidence for oxidative phosphorylation in erythrocytic stage parasites but at a level much lower than that observed in mammalian cells. Lastly, we developed an assay platform for target identification and mode of action studies of mitochondria-targeting antimalarials. This study provides new insights into the bioenergetics and metabolomics of the Plasmodium mitochondria.

Plasmodium immunomics.

PubMed

Doolan, Denise L

2011-01-01

The Plasmodium parasite, the causative agent of malaria, is an excellent model for immunomic-based approaches to vaccine development. The Plasmodium parasite has a complex life cycle with multiple stages and stage-specific expression of ∼5300 putative proteins. No malaria vaccine has yet been licensed. Many believe that an effective vaccine will need to target several antigens and multiple stages, and will require the generation of both antibody and cellular immune responses. Vaccine efforts to date have been stage-specific and based on only a very limited number of proteins representing <0.5% of the genome. The recent availability of comprehensive genomic, proteomic and transcriptomic datasets from human and selected non-human primate and rodent malarias provide a foundation to exploit for vaccine development. This information can be mined to identify promising vaccine candidate antigens, by proteome-wide screening of antibody and T cell reactivity using specimens from individuals exposed to malaria and technology platforms such as protein arrays, high throughput protein production and epitope prediction algorithms. Such antigens could be incorporated into a rational vaccine development process that targets specific stages of the Plasmodium parasite life cycle with immune responses implicated in parasite elimination and control. Immunomic approaches which enable the selection of the best possible targets by prioritising antigens according to clinically relevant criteria may overcome the problem of poorly immunogenic, poorly protective vaccines that has plagued malaria vaccine developers for the past 25 years. Herein, current progress and perspectives regarding Plasmodium immunomics are reviewed. Copyright © 2010 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Asymptomatic Plasmodium Infections in Children in Low Malaria Transmission Setting, Southwestern Uganda(1).

PubMed

Roh, Michelle E; Oyet, Caesar; Orikiriza, Patrick; Wade, Martina; Kiwanuka, Gertrude N; Mwanga-Amumpaire, Juliet; Parikh, Sunil; Boum, Yap

2016-08-01

A survey of asymptomatic children in Uganda showed Plasmodium malariae and P. falciparum parasites in 45% and 55% of microscopy-positive samples, respectively. Although 36% of microscopy-positive samples were negative by rapid diagnostic test, 75% showed P. malariae or P. ovale parasites by PCR, indicating that routine diagnostic testing misses many non-P. falciparum malarial infections.

Electron Microscopy to Correlate Cell Structure and Biochemical Activity

DTIC Science & Technology

1993-03-10

prevent and/or cure cerebral malaria. d) Morphological effects of artemisinin in Plasmodium falciparum In collaboration with Dr. Milhous of WRAR...uitrastructural changes induced in jPlasmodium falciparum, by artemisinin were studied in vitro. Two hours after administration, changes were...Electron microscope autoradiography was performed after [5H]-dihydroartemisinin and [uC]- artemisinin were administered to infected erythrocytes in

Reemergence of Plasmodium vivax malaria in the republic of Korea.

PubMed Central

Feighner, B. H.; Pak, S. I.; Novakoski, W. L.; Kelsey, L. L.; Strickman, D.

1998-01-01

Plasmodium vivax malaria reemerged in the Republic of Korea in 1993. The number of cases has tripled each year since, with more than 1,600 cases reported in 1997. All 27 cases in U.S. troops resolved uneventfully with chloroquine/primaquine therapy. Disease is localized along the western Demilitarized Zone and presents minimal risk to tourists. PMID:9621202

Molecular Surveillance for Multidrug-Resistant Plasmodium falciparum, Cambodia

PubMed Central

Shah, Naman K.; Alker, Alisa P.; Sem, Rithy; Susanti, Agustina Ika; Muth, Sinuon; Maguire, Jason D.; Duong, Socheat; Ariey, Frederic; Meshnick, Steven R.

2008-01-01

We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective. PMID:18826834

Plasmodium vivax malaria in a Romanian traveller returning from Greece, August 2011.

PubMed

Florescu, S A; Popescu, C P; Calistru, P; Ceausu, E; Nica, M; Toderan, A; Zaharia, M; Parola, P

2011-09-01

In August 2011, a Plasmodium vivax malaria infection was diagnosed in a Romanian traveller returning from Greece. This case together with several reports over the past decade of autochthonous cases in Greece highlight that malaria should be considered as differential diagnosis in symptomatic travellers returning from this country. Travellers may serve as sentinels of emerging vector-borne diseases.

Monkey Malaria in a European Traveler Returning from Malaysia

PubMed Central

Marti, Hanspeter; Felger, Ingrid; Müller, Dania; Jokiranta, T. Sakari

2008-01-01

In 2007, a Finnish traveler was infected in Peninsular Malaysia with Plasmodium knowlesi, a parasite that usually causes malaria in monkeys. P. knowlesi has established itself as the fifth Plasmodium species that can cause human malaria. The disease is potentially life-threatening in humans; clinicians and laboratory personnel should become more aware of this pathogen in travelers. PMID:18760013

The Plasmodium falciparum Sexual Development Transcriptome: A Microarray Analysis using Ontology-Based Pattern Identification

DTIC Science & Technology

2005-06-17

ciparum. Mol Biochem Parasitol 1992;56(2):239–50. [56] Vinetz JM, Dave SK, Specht CA, et al. The chitinase PfCHT1 from the human malaria parasite Plasmodium...falciparum lacks proenzyme and chitin -binding domains and displays unique substrate prefer- ences. Proc Natl Acad Sci USA 1999;96(24):14061–6. [57

Imported chloroquine-resistant Plasmodium vivax in Singapore: case report and literature review.

PubMed

Lim, Poh Lian; Mok, Ying Juan; Lye, David C; Leo, Yee Sin

2010-01-01

Chloroquine-resistant Plasmodium vivax (CRPV) infection is emerging as a clinically significant problem. Detailed travel history is crucial to the management of imported malarial cases. We report a 58-year-old business traveler who returned from Indonesia and experienced relapse due to CRPV. The epidemiology and diagnostic challenges of CRPV for travel medicine clinicians are reviewed.

Interactive cost of Plasmodium infection and insecticide resistance in the malaria vector Anopheles gambiae.

PubMed

Alout, Haoues; Dabiré, Roch K; Djogbénou, Luc S; Abate, Luc; Corbel, Vincent; Chandre, Fabrice; Cohuet, Anna

2016-07-19

Insecticide resistance raises concerns for the control of vector-borne diseases. However, its impact on parasite transmission could be diverse when considering the ecological interactions between vector and parasite. Thus we investigated the fitness cost associated with insecticide resistance and Plasmodium falciparum infection as well as their interactive cost on Anopheles gambiae survival and fecundity. In absence of infection, we observed a cost on fecundity associated with insecticide resistance. However, survival was higher for mosquito bearing the kdr mutation and equal for those with the ace-1(R) mutation compared to their insecticide susceptible counterparts. Interestingly, Plasmodium infection reduced survival only in the insecticide resistant strains but not in the susceptible one and infection was associated with an increase in fecundity independently of the strain considered. This study provides evidence for a survival cost associated with infection by Plasmodium parasite only in mosquito selected for insecticide resistance. This suggests that the selection of insecticide resistance mutation may have disturbed the interaction between parasites and vectors, resulting in increased cost of infection. Considering the fitness cost as well as other ecological aspects of this natural mosquito-parasite combination is important to predict the epidemiological impact of insecticide resistance.

4-Aminoquinoline derivatives: Synthesis, in vitro and in vivo antiplasmodial activity against chloroquine-resistant parasites.

PubMed

Singh, Shailja; Agarwal, Drishti; Sharma, Kumkum; Sharma, Manish; Nielsen, Morten A; Alifrangis, Michael; Singh, Ashok K; Gupta, Rinkoo D; Awasthi, Satish K

2016-10-21

Synthetic quinoline derivatives continue to be considered as candidates for new drug discovery if they act against CQ-resistant strains of malaria even after the widespread emergence of resistance to CQ. In this study, we explored the activities of two series of new 4-aminoquinoline derivatives and found them to be effective against Plasmodium falciparum under in vitro conditions. Further, we selected four most active derivatives 1m, 1o, 2c and 2j and evaluated their antimalarial potential against Plasmodium berghei in vivo. These 4-aminoquinolines cured BALB/c mice infected with P. berghei. The ED50 values were calculated to be 2.062, 2.231, 1.431, 1.623 and 1.18 mg/kg of body weight for each of the compounds 1m, 1o, 2c, 2j and amodiaquine, respectively. Total doses of 500 mg/kg of body weight were well received. The study suggests that these new 4-aminoquinolines should be used for structure activity relationship to find lead molecules for treating multidrug-resistant Plasmodium falciparum and Plasmodium vivax. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Artemisinin-based antimalarial research: application of biotechnology to the production of artemisinin, its mode of action, and the mechanism of resistance of Plasmodium parasites.

PubMed

Muangphrom, Paskorn; Seki, Hikaru; Fukushima, Ery Odette; Muranaka, Toshiya

2016-07-01

Malaria is a worldwide disease caused by Plasmodium parasites. A sesquiterpene endoperoxide artemisinin isolated from Artemisia annua was discovered and has been accepted for its use in artemisinin-based combinatorial therapies, as the most effective current antimalarial treatment. However, the quantity of this compound produced from the A. annua plant is very low, and the availability of artemisinin is insufficient to treat all infected patients. In addition, the emergence of artemisinin-resistant Plasmodium has been reported recently. Several techniques have been applied to enhance artemisinin availability, and studies related to its mode of action and the mechanism of resistance of malaria-causing parasites are ongoing. In this review, we summarize the application of modern technologies to improve the production of artemisinin, including our ongoing research on artemisinin biosynthetic genes in other Artemisia species. The current understanding of the mode of action of artemisinin as well as the mechanism of resistance against this compound in Plasmodium parasites is also presented. Finally, the current situation of malaria infection and the future direction of antimalarial drug development are discussed.

Susceptibility to Plasmodium yoelii Preerythrocytic Infection in BALB/c Substrains Is Determined at the Point of Hepatocyte Invasion

PubMed Central

Kaushansky, Alexis; Austin, Laura S.; Mikolajczak, Sebastian A.; Lo, Fang Y.; Miller, Jessica L.; Douglass, Alyse N.; Arang, Nadia; Vaughan, Ashley M.; Gardner, Malcolm J.

2014-01-01

After transmission by Anopheles mosquitoes, Plasmodium sporozoites travel to the liver, infect hepatocytes, and rapidly develop as intrahepatocytic liver stages (LS). Rodent models of malaria exhibit large differences in the magnitude of liver infection, both between parasite species and between strains of mice. This has been mainly attributed to differences in innate immune responses and parasite infectivity. Here, we report that BALB/cByJ mice are more susceptible to Plasmodium yoelii preerythrocytic infection than BALB/cJ mice. This difference occurs at the level of early hepatocyte infection, but expression levels of reported host factors that are involved in infection do not correlate with susceptibility. Interestingly, BALB/cByJ hepatocytes are more frequently polyploid; thus, their susceptibility converges on the previously observed preference of sporozoites to infect polyploid hepatocytes. Gene expression analysis demonstrates hepatocyte-specific differences in mRNA abundance for numerous genes between BALB/cByJ and BALB/cJ mice, some of which encode hepatocyte surface molecules. These data suggest that a yet-unknown receptor for sporozoite infection, present at elevated levels on BALB/cByJ hepatocytes and also polyploid hepatocytes, might facilitate Plasmodium liver infection. PMID:25312960

Rodent malaria-resistant strains of the mosquito, Anopheles gambiae, have slower population growth than -susceptible strains

PubMed Central

Voordouw, Maarten J; Anholt, Bradley R; Taylor, Pam J; Hurd, Hilary

2009-01-01

Background Trade-offs between anti-parasite defence mechanisms and other life history traits limit the evolution of host resistance to parasites and have important implications for understanding diseases such as malaria. Mosquitoes have not evolved complete resistance to malaria parasites and one hypothesis is that anti-malaria defence mechanisms are costly. Results We used matrix population models to compare the population growth rates among lines of Anopheles gambiae that had been selected for resistance or high susceptibility to the rodent malaria parasite, Plasmodium yoelii nigeriensis. The population growth rate of the resistant line was significantly lower than that of the highly susceptible and the unselected control lines, regardless of whether mosquitoes were infected with Plasmodium or not. The lower population growth of malaria-resistant mosquitoes was caused by reduced post blood-feeding survival of females and poor egg hatching. Conclusion With respect to eradicating malaria, the strategy of releasing Plasmodium-resistant Anopheles mosquitoes is unlikely to be successful if the costs of Plasmodium-resistance in the field are as great as the ones measured in this study. High densities of malaria-resistant mosquitoes would have to be maintained by continuous release from captive breeding facilities. PMID:19379508

Asymptomatic infection in individuals from the municipality of Barcelos (Brazilian Amazon) is not associated with the anti-Plasmodium falciparum glycosylphosphatidylinositol antibody response

PubMed Central

Gomes, Larissa Rodrigues; Totino, Paulo Renato Rivas; Sanchez, Maria Carmen Arroyo; Daniel, Elsa Paula da Silva Kaingona; de Macedo, Cristiana Santos; Fortes, Filomeno; Coura, José Rodrigues; Santi, Silvia Maria Di; Werneck, Guilherme Loureiro; Suárez-Mutis, Martha Cecilia; Ferreira-da-Cruz, Maria de Fátima; Daniel-Ribeiro, Cláudio Tadeu

2013-01-01

Anti-glycosylphosphatidylinositol (GPI) antibodies (Abs) may reflect and mediate, at least partially, anti-disease immunity in malaria by neutralising the toxic effect of parasitic GPI. Thus, we assessed the anti-GPI Ab response in asymptomatic individuals living in an area of the Brazilian Amazon that has a high level of malaria transmission. For comparative purposes, we also investigated the Ab response to a crude extract prepared from Plasmodium falciparum, the merozoite surface protein (MSP)3 antigen of P. falciparum and the MSP 1 antigen of Plasmodium vivax (PvMSP1-19) in these individuals and in Angolan patients with acute malaria. Our data suggest that the Ab response against P. falciparum GPI is not associated with P. falciparum asymptomatic infection in individuals who have been chronically exposed to malaria in the Brazilian Amazon. However, this Ab response could be related to ongoing parasitaemia (as was previously shown) in the Angolan patients. In addition, our data show that PvMSP1-19may be a good marker antigen to reflect previous exposure to Plasmodium in areas that have a high transmission rate of P. vivax. PMID:24037204

Evaluation of Recombinant Plasmodium knowlesi Merozoite Surface Protein-133 for Detection of Human Malaria

PubMed Central

Cheong, Fei Wen; Lau, Yee Ling; Fong, Mun Yik; Mahmud, Rohela

2013-01-01

Plasmodium knowlesi is now known as the fifth Plasmodium species that can cause human malaria. The Plasmodium merozoite surface protein (MSP) has been reported to be potential target for vaccination and diagnosis of malaria. MSP-133 has been shown to be immunogenic and its T cell epitopes could mediate cellular immune protection. However, limited studies have focused on P. knowlesi MSP-133. In this study, an approximately 28-kDa recombinant P. knowlesi MSP-133 (pkMSP-133) was expressed by using an Escherichia coli system. The purified pkMSP-133 reacted with serum samples of patients infected with P. knowlesi (31 of 31, 100%) and non-P. knowlesi malaria (27 of 28, 96.43%) by Western blotting. The pkMSP-133 also reacted with P. knowlesi (25 of 31, 80.65%) and non-P. knowlesi malaria sera (20 of 28, 71.43%) in an enzyme-linked immunosorbent assay (ELISA). Most of the non-malarial infection (49 of 52 in by Western blotting and 46 of 52 in the ELISA) and healthy donor serum samples (65 of 65 by Western blotting and ELISA) did not react with recombinant pkMSP-133. PMID:23509118

Comparison of the Performances of Five Primer Sets for the Detection and Quantification of Plasmodium in Anopheline Vectors by Real-Time PCR.

PubMed

Chaumeau, V; Andolina, C; Fustec, B; Tuikue Ndam, N; Brengues, C; Herder, S; Cerqueira, D; Chareonviriyaphap, T; Nosten, F; Corbel, V

2016-01-01

Quantitative real-time polymerase chain reaction (qrtPCR) has made a significant improvement for the detection of Plasmodium in anopheline vectors. A wide variety of primers has been used in different assays, mostly adapted from molecular diagnosis of malaria in human. However, such an adaptation can impact the sensitivity of the PCR. Therefore we compared the sensitivity of five primer sets with different molecular targets on blood stages, sporozoites and oocysts standards of Plasmodium falciparum (Pf) and P. vivax (Pv). Dilution series of standard DNA were used to discriminate between methods at low concentrations of parasite and to generate standard curves suitable for the absolute quantification of Plasmodium sporozoites. Our results showed that the best primers to detect blood stages were not necessarily the best ones to detect sporozoites. Absolute detection threshold of our qrtPCR assay varied between 3.6 and 360 Pv sporozoites and between 6 and 600 Pf sporozoites per mosquito according to the primer set used in the reaction mix. In this paper, we discuss the general performance of each primer set and highlight the need to use efficient detection methods for transmission studies.

Comparison of the Performances of Five Primer Sets for the Detection and Quantification of Plasmodium in Anopheline Vectors by Real-Time PCR

PubMed Central

Chaumeau, V.; Andolina, C.; Fustec, B.; Tuikue Ndam, N.; Brengues, C.; Herder, S.; Cerqueira, D.; Chareonviriyaphap, T.; Nosten, F.; Corbel, V.

2016-01-01

Quantitative real-time polymerase chain reaction (qrtPCR) has made a significant improvement for the detection of Plasmodium in anopheline vectors. A wide variety of primers has been used in different assays, mostly adapted from molecular diagnosis of malaria in human. However, such an adaptation can impact the sensitivity of the PCR. Therefore we compared the sensitivity of five primer sets with different molecular targets on blood stages, sporozoites and oocysts standards of Plasmodium falciparum (Pf) and P. vivax (Pv). Dilution series of standard DNA were used to discriminate between methods at low concentrations of parasite and to generate standard curves suitable for the absolute quantification of Plasmodium sporozoites. Our results showed that the best primers to detect blood stages were not necessarily the best ones to detect sporozoites. Absolute detection threshold of our qrtPCR assay varied between 3.6 and 360 Pv sporozoites and between 6 and 600 Pf sporozoites per mosquito according to the primer set used in the reaction mix. In this paper, we discuss the general performance of each primer set and highlight the need to use efficient detection methods for transmission studies. PMID:27441839

Remarkable interkingdom conservation of intron positions and massive, lineage-specific intron loss and gain in eukaryotic evolution.

PubMed

Rogozin, Igor B; Wolf, Yuri I; Sorokin, Alexander V; Mirkin, Boris G; Koonin, Eugene V

2003-09-02

Sequencing of eukaryotic genomes allows one to address major evolutionary problems, such as the evolution of gene structure. We compared the intron positions in 684 orthologous gene sets from 8 complete genomes of animals, plants, fungi, and protists and constructed parsimonious scenarios of evolution of the exon-intron structure for the respective genes. Approximately one-third of the introns in the malaria parasite Plasmodium falciparum are shared with at least one crown group eukaryote; this number indicates that these introns have been conserved through >1.5 billion years of evolution that separate Plasmodium from the crown group. Paradoxically, humans share many more introns with the plant Arabidopsis thaliana than with the fly or nematode. The inferred evolutionary scenario holds that the common ancestor of Plasmodium and the crown group and, especially, the common ancestor of animals, plants, and fungi had numerous introns. Most of these ancestral introns, which are retained in the genomes of vertebrates and plants, have been lost in fungi, nematodes, arthropods, and probably Plasmodium. In addition, numerous introns have been inserted into vertebrate and plant genes, whereas, in other lineages, intron gain was much less prominent.

Prevalence of mutation and phenotypic expression associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum and Plasmodium vivax.

PubMed

Zakai, Haytham A; Khan, Wajihullah; Asma, Umme

2013-09-01

Therapeutic efficacy of sulfadoxine-pyrimethamine (SP), which is commonly used to treat falciparum malaria, was assessed in isolates of Plasmodium falciparum (Welch, 1897) and Plasmodium vivax (Grassi et Feletti, 1890) ofAligarh, Uttar Pradesh, North India and Taif, Saudi Arabia during 2011-2012. Both the species showed mutations in dihydrofolate reductase (DHFR) enzyme as they have common biochemical drug targets. Mutation rate for pfdhfr was higher compared to pvdhfr because the drug was mainly given to treat falciparum malaria. Since both the species coexist, P. vivax was also exposed to SP due to faulty species diagnosis or medication without specific diagnosis. Low level of mutations against SP in P. falciparum of Saudi isolates indicates that the SP combination is still effective for the treatment of falciparum malaria. Since SP is used as first-line of treatment because of high level of resistance against chloroquine (CQ), it may result in spread of higher level of mutations resulting in drug resistance and treatment failure in near future. Therefore, to avoid further higher mutations in the parasite, use of better treatment regimens such as artesunate combination therapy must be introduced against SP combination.

Chickens treated with a nitric oxide inhibitor became more resistant to Plasmodium gallinaceum infection due to reduced anemia, thrombocytopenia and inflammation

PubMed Central

2013-01-01

Malaria is a serious infectious disease caused by parasites of the Plasmodium genus that affect different vertebrate hosts. Severe malaria leads to host death and involves different pathophysiological phenomena such as anemia, thrombocytopenia and inflammation. Nitric oxide (NO) is an important effector molecule in this disease, but little is known about its role in avian malaria models. Plasmodium gallinaceum- infected chickens were treated with aminoguanidine (AG), an inhibitor of inducible nitric oxide synthase, to observe the role of NO in the pathogenesis of this avian model. AG increased the survival of chickens, but also induced higher parasitemia. Treated chickens demonstrated reduced anemia and thrombocytopenia. Moreover, erythrocytes at different stages of maturation, heterophils, monocytes and thrombocytes were infected by Plasmodium gallinaceum and animals presented a generalized leucopenia. Activated leukocytes and thrombocytes with elongated double nuclei were observed in chickens with higher parasitemia; however, eosinophils were not involved in the infection. AG reduced levels of hemozoin in the spleen and liver, indicating lower inflammation. Taken together, the results suggest that AG reduced anemia, thrombocytopenia and inflammation, explaining the greater survival rate of the treated chickens. PMID:23398940

Translational Control in Plasmodium and Toxoplasma Parasites

PubMed Central

Joyce, Bradley R.; Sullivan, William J.; Nussenzweig, Victor

2013-01-01

The life cycles of apicomplexan parasites such as Plasmodium spp. and Toxoplasma gondii are complex, consisting of proliferative and latent stages within multiple hosts. Dramatic transformations take place during the cycles, and they demand precise control of gene expression at all levels, including translation. This review focuses on the mechanisms that regulate translational control in Plasmodium and Toxoplasma, with a particular emphasis on the phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Phosphorylation of eIF2α (eIF2α∼P) is a conserved mechanism that eukaryotic cells use to repress global protein synthesis while enhancing gene-specific translation of a subset of mRNAs. Elevated levels of eIF2α∼P have been observed during latent stages in both Toxoplasma and Plasmodium, indicating that translational control plays a role in maintaining dormancy. Parasite-specific eIF2α kinases and phosphatases are also required for proper developmental transitions and adaptation to cellular stresses encountered during the life cycle. Identification of small-molecule inhibitors of apicomplexan eIF2α kinases may selectively interfere with parasite translational control and lead to the development of new therapies to treat malaria and toxoplasmosis. PMID:23243065

Translational control in Plasmodium and toxoplasma parasites.

PubMed

Zhang, Min; Joyce, Bradley R; Sullivan, William J; Nussenzweig, Victor

2013-02-01

The life cycles of apicomplexan parasites such as Plasmodium spp. and Toxoplasma gondii are complex, consisting of proliferative and latent stages within multiple hosts. Dramatic transformations take place during the cycles, and they demand precise control of gene expression at all levels, including translation. This review focuses on the mechanisms that regulate translational control in Plasmodium and Toxoplasma, with a particular emphasis on the phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Phosphorylation of eIF2α (eIF2α∼P) is a conserved mechanism that eukaryotic cells use to repress global protein synthesis while enhancing gene-specific translation of a subset of mRNAs. Elevated levels of eIF2α∼P have been observed during latent stages in both Toxoplasma and Plasmodium, indicating that translational control plays a role in maintaining dormancy. Parasite-specific eIF2α kinases and phosphatases are also required for proper developmental transitions and adaptation to cellular stresses encountered during the life cycle. Identification of small-molecule inhibitors of apicomplexan eIF2α kinases may selectively interfere with parasite translational control and lead to the development of new therapies to treat malaria and toxoplasmosis.

Effect of tamoxifen on the sphingolipid biosynthetic pathway in the different intraerythrocytic stages of the apicomplexa Plasmodium falciparum.

PubMed

Piñero, Tamara A; Landoni, Malena; Duschak, Vilma G; Katzin, Alejandro M; Couto, Alicia S

2018-03-18

Parasites of the genus Plasmodium responsible for Malaria are obligate intracellular pathogens residing in mammalian red blood cells, hepatocytes, or mosquito midgut epithelial cells. Regarding that detailed knowledge on the sphingolipid biosynthetic pathway of the apicomplexan protozoan parasites is scarce, different stages of Plasmodium falciparum were treated with tamoxifen in order to evaluate the effects of this drug on the glycosphingolipid biosynthesis. Thin layer chromatography, High performance reverse phase chromatography and UV-MALDI-TOF mass spectrometry were the tools used for the analysis. In the ring forms, the increase of NBD-phosphatidyl inositol biosynthesis was notorious but differences at NBD-GlcCer levels were undetectable. In trophozoite forms, an abrupt decrease of NBD-acylated GlcDHCer and NBD-GlcDHCer in addition to an increase of NBD-PC biosynthesis was observed. On the contrary, in schizonts, tamoxifen seems not to be producing substantial changes in lipid biosynthesis. Our findings indicate that in this parasite, tamoxifen is exerting an inhibitory action on Glucosylceramidesynthase and sphingomyelin synthase levels. Moreover, regarding that Plasmodium does not biosynthesize inositolphosphoceramides, the accumulation of phosphatidylinositol should indicate an inhibitory action on glycosylinositol phospholipid synthesis. Copyright © 2018 Elsevier Inc. All rights reserved.

Epidemiology of Plasmodium vivax in Indonesia.

PubMed

Surjadjaja, Claudia; Surya, Asik; Baird, J Kevin

2016-12-28

Endemic malaria occurs across much of the vast Indonesian archipelago. All five species of Plasmodium known to naturally infect humans occur here, along with 20 species of Anopheles mosquitoes confirmed as carriers of malaria. Two species of plasmodia cause the overwhelming majority and virtually equal shares of malaria infections in Indonesia: Plasmodium falciparum and Plasmodium vivax The challenge posed by P. vivax is especially steep in Indonesia because chloroquine-resistant strains predominate, along with Chesson-like strains that relapse quickly and multiple times at short intervals in almost all patients. Indonesia's hugely diverse human population carries many variants of glucose-6-phosphate dehydrogenase (G6PD) deficiency, most of them exhibiting severely impaired enzyme activity. Therefore, the patients most likely to benefit from primaquine therapy by preventing aggressive relapse, may also be most likely to suffer harm without G6PD deficiency screening. Indonesia faces the challenge of controlling and eventually eliminating malaria across > 13,500 islands stretching > 5,000 km and an enormous diversity of ecological, ethnographic, and socioeconomic settings, and extensive human migrations. This article describes the occurrence of P. vivax in Indonesia and the obstacles faced in eliminating its transmission. © The American Society of Tropical Medicine and Hygiene.

Epidemiology of Plasmodium vivax in Indonesia

PubMed Central

Surjadjaja, Claudia; Surya, Asik; Baird, J. Kevin

2016-01-01

Endemic malaria occurs across much of the vast Indonesian archipelago. All five species of Plasmodium known to naturally infect humans occur here, along with 20 species of Anopheles mosquitoes confirmed as carriers of malaria. Two species of plasmodia cause the overwhelming majority and virtually equal shares of malaria infections in Indonesia: Plasmodium falciparum and Plasmodium vivax. The challenge posed by P. vivax is especially steep in Indonesia because chloroquine-resistant strains predominate, along with Chesson-like strains that relapse quickly and multiple times at short intervals in almost all patients. Indonesia's hugely diverse human population carries many variants of glucose-6-phosphate dehydrogenase (G6PD) deficiency, most of them exhibiting severely impaired enzyme activity. Therefore, the patients most likely to benefit from primaquine therapy by preventing aggressive relapse, may also be most likely to suffer harm without G6PD deficiency screening. Indonesia faces the challenge of controlling and eventually eliminating malaria across > 13,500 islands stretching > 5,000 km and an enormous diversity of ecological, ethnographic, and socioeconomic settings, and extensive human migrations. This article describes the occurrence of P. vivax in Indonesia and the obstacles faced in eliminating its transmission. PMID:27708185

In vivo Susceptibility of Plasmodium vivax to Chloroquine in Southeastern Iran.

PubMed

Heidari, A; Keshavarz, H; Shojaee, S; Raeisi, A; Dittrich, S

2012-01-01

Plasmodium vivax is the predominant species causes of malaria with about 90% total annual reported malaria in Iran. This study conducted to determine the susceptibility of Plasmodium vivax isolates to chloroquine in Sistan and Balochistan Province, southeastern Iran. A total 270 subjects with symptomatic malaria and confirmed P. vivax infection completed the designed 28-day in vivo study. The thick and thin film blood smears were screened for malaria parasites by microscopy. The nested PCR was applied using the Plasmodium 18 subunit ribosomal ribonucleic (Ssr RNA) genes for detecting mixed infections and diagnosis of parasites in the samples with low parasite on days 0, 5, 6, 7, and 28. P. vivax was cleared in 15%, 50%, 95%, and 100% of patients on days 1, 2, 3, 4 respectively by microscopy assessment. Six patients were exhibited specific P. vivax band in nested PCR on day 5. No recurrence was observed on days 7, 14 and 28. Mean (±standard deviation) parasite clearance time was 2.41 (±0.8) days. P. vivax is still susceptible to chloroquine in Southeatern Iran. This finding is compatible with results of neighboring countries Pakistan and Afghanistan.

Uncovering the transmission dynamics of Plasmodium vivax using population genetics

PubMed Central

Barry, Alyssa E.; Waltmann, Andreea; Koepfli, Cristian; Barnadas, Celine; Mueller, Ivo

2015-01-01

Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes. PMID:25891915

Finding the sweet spots of inhibition: understanding the targets of a functional antibody against Plasmodium vivax Duffy binding protein.

PubMed

Ntumngia, Francis B; King, Christopher L; Adams, John H

2012-11-01

Plasmodium vivax Duffy binding protein region II (DBPII) is an essential ligand for reticulocyte invasion, thereby making this molecule an attractive vaccine candidate against asexual blood-stage P. vivax. Similar to other Plasmodium blood-stage vaccine candidates, strain-specific immunity due to DBPII allelic variation may complicate vaccine efficacy. Targeting immune responses to more conserved epitopes that are potential targets of strain-transcending neutralising immunity is necessary to avoid induction of strain-specific responses to dominant variant epitopes. In this article, we focus on different approaches to optimise the design of DBP immunogenicity to target conserved epitopes, which is important for developing a broadly effective vaccine against P. vivax. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Modeling the inhibition of quadruple mutant Plasmodium falciparum dihydrofolate reductase by pyrimethamine derivatives

NASA Astrophysics Data System (ADS)

Fogel, Gary B.; Cheung, Mars; Pittman, Eric; Hecht, David

2008-01-01

Modeling studies were performed on known inhibitors of the quadruple mutant Plasmodium falciparum dihydrofolate reductase (DHFR). GOLD was used to dock 32 pyrimethamine derivatives into the active site of DHFR obtained from the x-ray crystal structure 1J3K.pdb. Several scoring functions were evaluated and the Molegro Protein-Ligand Interaction Score was determined to have one of the best correlation to experimental p K i . In conjunction with Protein-Ligand Interaction scores, predicted binding modes and key protein-ligand interactions were evaluated and analyzed in order to develop criteria for selecting compounds having a greater chance of activity versus resistant strains of Plasmodium falciparum. This methodology will be used in future studies for selection of compounds for focused screening libraries.

Imported Malaria in Turkey: The Importance of Diagnosis and Treatment of Plasmodium falciparum/Plasmodium vivax Mixed Infection.

PubMed

Tünger, Özlem; Çakmak, Akide; Özbilgin, Ahmet; Tunalı, Varol; Çetin, Çiğdem Banu

2018-05-21

The most common types of malaria in the world are Plasmodium vivax and P. falciparum. In countries where both species are endemic, P. vivax and P. falciparum coinfection also occurs. Thus, the possibility of mixed malaria in Turkey should always be considered in cases with a traveling history to these countries. Here, we report a case of P. vivax/P. falciparum mixed infection that was diagnosed as P. falciparum malaria in Ethiopia. However, the administered treatment was inadequate, and infection recurred because of the miss in the diagnosis of P. vivax malaria, for which an effective drug for hypnozoites was not administered. This case report emphasizes the importance of diagnosis, correct and adequate treatment of infections, and a close follow-up of diseases.

Plasmodium malariae and Plasmodium ovale infections in the China-Myanmar border area.

PubMed

Li, Peipei; Zhao, Zhenjun; Xing, Hua; Li, Wenli; Zhu, Xiaotong; Cao, Yaming; Yang, Zhaoqing; Sattabongkot, Jetsumon; Yan, Guiyun; Fan, Qi; Cui, Liwang

2016-11-15

The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China-Myanmar border area and their genetic diversity. Epidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China-Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates. Analysis of 2701 blood samples collected from the China-Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates. The four human malaria parasite species all occurred sympatrically at the China-Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes.

Plasmodium knowlesi: from Malaysia, a novel health care threat.

PubMed

Sabbatani, Sergio; Fiorino, Sirio; Manfredi, Roberto

2012-03-01

Epidemic foci of Plasmodium knowlesi malaria have been identified during the past ten years in Malaysia, in particular in the States of Sarawak and Sabah (Malaysia Borneo), and in the Pahang region (peninsular Malaysia). Based on a review of the available recent international literature, the authors underline the importance of molecular biology examinations, polymerase chain reactions (PCR), performed with primers specific for P. knowlesi, since the current microscopic examination (haemoscope) may fail to distinguish P. knowlesi from Plasmodium malariae, due to the very similar appearance of the two parasites. P. knowlesi has been described as the causal agent of life-threatening and lethal forms of malaria: its clinical picture is more severe when compared with that of P. malariae, since the disease is characterized by greater parasitaemia, as opposed to that documented in the course of P. malariae disease. The most effective carrier is Anopheles leucosphyrus: this mosquito is attracted by both humans and monkeys. Among primates, the natural hosts of P. knowlesi are Macaca fascicularis and Macaca nemestina, while Saimiri scirea and Macaca mulatta, which cannot become infected in nature, may be useful in experimental models. When underlining the potentially severe evolution, we note the key role played by prompt disease recognition, which is expected to be more straightforward in patients monitored in endemic countries at high risk, but should be carefully implemented for subjects being admitted to hospital in Western countries suffering from the typical signs and symptoms of malaria, after travelling in South-East Asia where they were engaged in excursions in the tropical forest (trekking, and similar outdoor activities). In these cases, the diagnosis should be prompt, and suitable treatment should follow. According to data in the literature, in non-severe cases chloroquine proves very effective against P. knowlesi, achieving the disappearance of signs and symptoms in 96% of cases after only 24 hours after treatment start. In the light of the emerging epidemiological data, P. knowlesi should be added to Plasmodium vivax, Plasmodium ovale, P. malariae, and Plasmodium falciparum, as the fifth aetiological agent of malaria. During the next few years, it will become mandatory to plan an appropriate surveillance program of the epidemiological evolution, paying also great attention to the clinical features of patients affected by P. knowlesi malaria, which are expected to worsen according to the time elapsed; some studies seem to point out greater severity according to increased parasitaemia, paralleling the increased interhuman infectious passages of the plasmodium.

False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination

PubMed Central

2011-01-01

Background The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies. Methods Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a Plasmodium specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked. Results Specimens (N = 16,160) of seven anopheline species were tested by CSP-ELISA for Plasmodium falciparum and Plasmodium vivax (Pv210 and Pv247). Two new vector species were identified for the region: Anopheles pampanai (P. vivax) and Anopheles barbirostris (Plasmodium malariae). In 88% (155/176) of the mosquitoes found positive with the P. falciparum CSP-ELISA, the presence of Plasmodium sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for P. vivax CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of P. falciparum was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat-unstable cross-reacting antigen is mainly present in head and thorax and almost absent in the abdomens (4 out of 147) of the false positive specimens. Conclusion The CSP-ELISA can considerably overestimate the EIR, particularly for P. falciparum and for zoophilic species. The heat-unstable cross-reacting antigen in false positives remains unknown. Therefore it is highly recommended to confirm all positive CSP-ELISA results, either by re-analysing the heated ELISA lysate (100°C, 10 min), or by performing Plasmodium specific PCR followed if possible by sequencing of the amplicons for Plasmodium species determination. PMID:21767376

Amplification of a Gene Related to Mammalian mdr Genes in Drug-Resistant Plasmodium falciparum

NASA Astrophysics Data System (ADS)

Wilson, Craig M.; Serrano, Adelfa E.; Wasley, Annemarie; Bogenschutz, Michael P.; Shankar, Anuraj H.; Wirth, Dyann F.

1989-06-01

The malaria parasite Plasmodium falciparum contains at least two genes related to the mammalian multiple drug resistance genes, and at least one of the P. falciparum genes is expressed at a higher level and is present in higher copy number in a strain that is resistant to multiple drugs than in a strain that is sensitive to the drugs.

Using a Genome-Scale Metabolic Network Model to Elucidate the Mechanism of Chloroquine Action in Plasmodium falciparum

DTIC Science & Technology

2017-03-22

Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, US...2017 Available online 22 March 2017 Keywords: Plasmodium Chloroquine Metabolic network modeling Redox metabolism Carbon fixation* Corresponding... available (Antony and Parija, 2016), their efficacy has declined appreciably in the last few decades owing to widespread drug resistance developed by the

Structure of Plasmodium falciparum ADP-ribosylation factor 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, William J.; Smith, Craig D.; Senkovich, Olga

Vesicular trafficking may play a crucial role in the pathogenesis and survival of the malaria parasite. ADP-ribosylation factors (ARFs) are among the major components of vesicular trafficking pathways in eukaryotes. The crystal structure of ARF1 GTPase from Plasmodium falciparum has been determined in the GDP-bound conformation at 2.5 {angstrom} resolution and is compared with the structures of mammalian ARF1s.

Plasmodium Genus Assay Transition to the Joint Biological Agent Identification and Diagnostic System (JBAIDS)

DTIC Science & Technology

2012-07-12

readily transferable to diverse real-time PCR instrumentation. These assays are used regularly for vector surveillance and are the primary...instrumentation ( FilmArray ) is under assessment. Assay oligonucleotide sequences and formulations are available for use in future joint projects...Plasmodium real-time PCR detection capability has been challenging. During 2006, the Division of Entomology, WRAIR designed and developed a

Plasmodium falciparum: a simplified technique for obtaining singly infected erythrocytes.

PubMed

Puthia, Manoj K; Tan, Kevin S W

2005-02-01

We report the development of a simple technique involving 15 ml polypropylene tubes and a rotatory incubator for obtaining erythrocytes singly infected with Plasmodium falciparum. This technique will be useful for cloning of the parasite. Our finding that P. falciparum merozoite invasion is inhibited during rotation suggests that this method may also be useful for the study of parasite-erythrocyte interactions under dynamic circulatory conditions.

Computational identification of signalling pathways in Plasmodium falciparum.

PubMed

Oyelade, Jelili; Ewejobi, Itunu; Brors, Benedikt; Eils, Roland; Adebiyi, Ezekiel

2011-06-01

Malaria is one of the world's most common and serious diseases causing death of about 3 million people each year. Its most severe occurrence is caused by the protozoan Plasmodium falciparum. Reports have shown that the resistance of the parasite to existing drugs is increasing. Therefore, there is a huge and urgent need to discover and validate new drug or vaccine targets to enable the development of new treatments for malaria. The ability to discover these drug or vaccine targets can only be enhanced from our deep understanding of the detailed biology of the parasite, for example how cells function and how proteins organize into modules such as metabolic, regulatory and signal transduction pathways. It has been noted that the knowledge of signalling transduction pathways in Plasmodium is fundamental to aid the design of new strategies against malaria. This work uses a linear-time algorithm for finding paths in a network under modified biologically motivated constraints. We predicted several important signalling transduction pathways in Plasmodium falciparum. We have predicted a viable signalling pathway characterized in terms of the genes responsible that may be the PfPKB pathway recently elucidated in Plasmodium falciparum. We obtained from the FIKK family, a signal transduction pathway that ends up on a chloroquine resistance marker protein, which indicates that interference with FIKK proteins might reverse Plasmodium falciparum from resistant to sensitive phenotype. We also proposed a hypothesis that showed the FIKK proteins in this pathway as enabling the resistance parasite to have a mechanism for releasing chloroquine (via an efflux process). Furthermore, we also predicted a signalling pathway that may have been responsible for signalling the start of the invasion process of Red Blood Cell (RBC) by the merozoites. It has been noted that the understanding of this pathway will give insight into the parasite virulence and will facilitate rational vaccine design against merozoites invasion. And we have a host of other predicted pathways, some of which have been used in this work to predict the functionality of some proteins. Copyright © 2010 Elsevier B.V. All rights reserved.

Genetic variation of aldolase from Korean isolates of Plasmodium vivax and its usefulness in serodiagnosis.

PubMed

Kim, Jung-Yeon; Kim, Hyung-Hwan; Shin, Hyun-ll; Sohn, Youngjoo; Kim, Hyuck; Lee, Sang-Wook; Lee, Won-Ja; Lee, Hyeong-Woo

2012-05-08

The malaria aldolase is widely used as rapid diagnostic test (RDT), but the efficacy in aspect of its serological effectiveness in diagnosis is not known. The genetic variation of Korean isolates was analysed and recombinant aldolase was evaluated as a serological antigen in Plasmodium vivax malaria. Genomic DNA was purified and the aldolase gene of P. vivax from 25 patients' blood samples was amplified. The samples came from 5 epidemic areas; Bucheon-si, Gimpo-si, Paju-si of Gyeonggido, Gangwha-gun of Incheon metropolitan city, and Cheorwon of Gangwon-do, South Korea. The antigenicity of the recombinant aldolase was tested by western blot and enzyme-linked immunosorbent assay (ELISA). Sequence analysis of 25 Korean isolates of P. vivax showed that the open reading frame (ORF) of 1,110 nucleotides encoded a deduced protein of 369 amino acids (aa). This ORF showed 100% homology with the P. vivax Sal I strain (XM_00165894) and P. vivax WDK strain (AF247063), 87.4% homology with Plasmodium falciparum (AF179421), 90.6% homology with Plasmodium chabaudi (AF247060), 89.5% homology with Plasmodium vinckei (AF247061), and 96.7% homology with Plasmodium knowlesi. A single nucleotide polymorphism (SNP) at nucleotide 180 (G to A, n = 5) was also observed in the isolates. The expressed recombinant protein had a molecular weight of approximately 31 kDa (monomeric form) and 62 kDa (dimeric form) as analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Among 109 P. vivax patients, 32 (29.4%) had positive in an enzyme-linked absorbance assay (ELISA). This result showed significant correlation between ELISA and an indirect fluorescent antibody test (IFAT) (P < 0.0001). The aldolase gene from Korean isolates of P. vivax showed one SNP at nucleotide position 180; this SNP mutant was discovered in only the western part of Han River, and included the regions of Ganghwa, Gimpo, and Bucheon. Based on the results, the relationship between antibody production against aldolase and the pattern of disease onset should be more investigated before using aldolase for serodiagnosis.

Genetic variation of aldolase from Korean isolates of Plasmodium vivax and its usefulness in serodiagnosis

PubMed Central

2012-01-01

Background The malaria aldolase is widely used as rapid diagnostic test (RDT), but the efficacy in aspect of its serological effectiveness in diagnosis is not known. The genetic variation of Korean isolates was analysed and recombinant aldolase was evaluated as a serological antigen in Plasmodium vivax malaria. Methods Genomic DNA was purified and the aldolase gene of P. vivax from 25 patients’ blood samples was amplified. The samples came from 5 epidemic areas; Bucheon-si, Gimpo-si, Paju-si of Gyeonggido, Gangwha-gun of Incheon metropolitan city, and Cheorwon of Gangwon-do, South Korea. The antigenicity of the recombinant aldolase was tested by western blot and enzyme-linked immunosorbent assay (ELISA). Results Sequence analysis of 25 Korean isolates of P. vivax showed that the open reading frame (ORF) of 1,110 nucleotides encoded a deduced protein of 369 amino acids (aa). This ORF showed 100% homology with the P. vivax Sal I strain (XM_00165894) and P. vivax WDK strain (AF247063), 87.4% homology with Plasmodium falciparum (AF179421), 90.6% homology with Plasmodium chabaudi (AF247060), 89.5% homology with Plasmodium vinckei (AF247061), and 96.7% homology with Plasmodium knowlesi. A single nucleotide polymorphism (SNP) at nucleotide 180 (G to A, n = 5) was also observed in the isolates. The expressed recombinant protein had a molecular weight of approximately 31 kDa (monomeric form) and 62 kDa (dimeric form) as analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Among 109 P. vivax patients, 32 (29.4%) had positive in an enzyme-linked absorbance assay (ELISA). This result showed significant correlation between ELISA and an indirect fluorescent antibody test (IFAT) (P < 0.0001). Conclusions The aldolase gene from Korean isolates of P. vivax showed one SNP at nucleotide position 180; this SNP mutant was discovered in only the western part of Han River, and included the regions of Ganghwa, Gimpo, and Bucheon. Based on the results, the relationship between antibody production against aldolase and the pattern of disease onset should be more investigated before using aldolase for serodiagnosis. PMID:22569198

A bioinformatic survey of RNA-binding proteins in Plasmodium.

PubMed

Reddy, B P Niranjan; Shrestha, Sony; Hart, Kevin J; Liang, Xiaoying; Kemirembe, Karen; Cui, Liwang; Lindner, Scott E

2015-11-02

The malaria parasites in the genus Plasmodium have a very complicated life cycle involving an invertebrate vector and a vertebrate host. RNA-binding proteins (RBPs) are critical factors involved in every aspect of the development of these parasites. However, very few RBPs have been functionally characterized to date in the human parasite Plasmodium falciparum. Using different bioinformatic methods and tools we searched P. falciparum genome to list and annotate RBPs. A representative 3D models for each of the RBD domain identified in P. falciparum was created using I-TESSAR and SWISS-MODEL. Microarray and RNAseq data analysis pertaining PfRBPs was performed using MeV software. Finally, Cytoscape was used to create protein-protein interaction network for CITH-Dozi and Caf1-CCR4-Not complexes. We report the identification of 189 putative RBP genes belonging to 13 different families in Plasmodium, which comprise 3.5% of all annotated genes. Almost 90% (169/189) of these genes belong to six prominent RBP classes, namely RNA recognition motifs, DEAD/H-box RNA helicases, K homology, Zinc finger, Puf and Alba gene families. Interestingly, almost all of the identified RNA-binding helicases and KH genes have cognate homologs in model species, suggesting their evolutionary conservation. Exploration of the existing P. falciparum blood-stage transcriptomes revealed that most RBPs have peak mRNA expression levels early during the intraerythrocytic development cycle, which taper off in later stages. Nearly 27% of RBPs have elevated expression in gametocytes, while 47 and 24% have elevated mRNA expression in ookinete and asexual stages. Comparative interactome analyses using human and Plasmodium protein-protein interaction datasets suggest extensive conservation of the PfCITH/PfDOZI and PfCaf1-CCR4-NOT complexes. The Plasmodium parasites possess a large number of putative RBPs belonging to most of RBP families identified so far, suggesting the presence of extensive post-transcriptional regulation in these parasites. Taken together, in silico identification of these putative RBPs provides a foundation for future functional studies aimed at defining a unique network of post-transcriptional regulation in P. falciparum.

Melatonin effects on Plasmodium life cycle: new avenues for therapeutic approach.

PubMed

Srinivasan, Venkataramanujam; Ahmad, Asma H; Mohamed, Mahaneem; Zakaria, Rahimah

2012-05-01

Malaria remains a global health problem affecting more than 515 million people all over the world including Malaysia. It is on the rise, even within unknown regions that previous to this were free of malaria. Although malaria eradication programs carried out by vector control programs are still effective, anti-malarial drugs are also used extensively for curtailing this disease. But resistance to the use of anti-malarial drugs is also increasing on a daily basis. With an increased understanding of mechanisms that cause growth, differentiation and development of malarial parasites in rodents and humans, new avenues of therapeutic approaches for controlling the growth, synchronization and development of malarial parasites are essential. Within this context, the recent discoveries related to IP3 interconnected signalling pathways, the release of Ca2+ from intracellular stores of Plasmodium, ubiquitin protease systems as a signalling pathway, and melatonin influencing the growth and differentiation of malarial parasites by its effects on these signalling pathways have opened new therapeutic avenues for arresting the growth and differentiation of malarial parasites. Indeed, the use of melatonin antagonist, luzindole, has inhibited the melatonin's effect on these signalling pathways and thereby has effectively reduced the growth and differentiation of malarial parasites. As Plasmodium has effective sensors which detect the nocturnal plasma melatonin concentrations, suppression of plasma melatonin levels with the use of bright light during the night or by anti-melatonergic drugs and by using anti-kinase drugs will help in eradicating malaria on a global level. A number of patients have been admitted with regards to the control and management of malarial growth. Patents related to the discovery of serpentine receptors on Plasmodium, essential for modulating intra parasitic melatonin levels, procedures for effective delivery of bright light to suppress plasma melatonin levels and thereby arresting the growth and elimination of malarial parasites from the blood of the host are all cited in the paper. The purpose of the paper is to highlight the importance of melatonin acting as a cue for Plasmodium faciparum growth and to discuss the ways of curbing the effects of melatonin on Plasmodium growth and for arresting its life cycle, as a method of eliminating the parasite from the host.

Avian malaria in a boreal resident species: long-term temporal variability, and increased prevalence in birds with avian keratin disorder

USGS Publications Warehouse

Wilkinson, Laura C.; Handel, Colleen M.; Van Hemert, Caroline R.; Loiseau, Claire; Sehgal, Ravinder N. M.

2016-01-01

The prevalence of vector-borne parasitic diseases is widely influenced by biological and ecological factors. Environmental conditions such as temperature and precipitation can have a marked effect on haemosporidian parasites (Plasmodium spp.) that cause malaria and those that cause other malaria-like diseases in birds. However, there have been few long-term studies monitoring haemosporidian infections in birds in northern latitudes, where weather conditions can be highly variable and the effects of climate change are becoming more pronounced. We used molecular methods to screen more than 2,000 blood samples collected from black-capped chickadees (Poecile atricapillus), a resident passerine bird. Samples were collected over a 10 year period, mostly during the non-breeding season, at seven sites in Alaska, USA. We tested for associations between Plasmodium prevalence and local environmental conditions including temperature, precipitation, site, year and season. We also evaluated the relationship between parasite prevalence and individual host factors of age, sex and presence or absence of avian keratin disorder. This disease, which causes accelerated keratin growth in the beak, provided a natural study system in which to test the interaction between disease state and malaria prevalence. Prevalence of Plasmodium infection varied by year, site, age and individual disease status but there was no support for an effect of sex or seasonal period. Significantly, birds with avian keratin disorder were 2.6 times more likely to be infected by Plasmodium than birds without the disorder. Interannual variation in the prevalence of Plasmodium infection at different sites was positively correlated with summer temperatures at the local but not statewide scale. Sequence analysis of the parasite cytochrome b gene revealed a single Plasmodiumspp. lineage, P43. Our results demonstrate associations between prevalence of avian malaria and a variety of biological and ecological factors. These results also provide important baseline data that will be informative for predicting future changes inPlasmodium prevalence in the subarctic.

Plasmodium Parasitemia Associated With Increased Survival in Ebola Virus-Infected Patients.

PubMed

Rosenke, Kyle; Adjemian, Jennifer; Munster, Vincent J; Marzi, Andrea; Falzarano, Darryl; Onyango, Clayton O; Ochieng, Melvin; Juma, Bonventure; Fischer, Robert J; Prescott, Joseph B; Safronetz, David; Omballa, Victor; Owuor, Collins; Hoenen, Thomas; Groseth, Allison; Martellaro, Cynthia; van Doremalen, Neeltje; Zemtsova, Galina; Self, Joshua; Bushmaker, Trenton; McNally, Kristin; Rowe, Thomas; Emery, Shannon L; Feldmann, Friederike; Williamson, Brandi N; Best, Sonja M; Nyenswah, Tolbert G; Grolla, Allen; Strong, James E; Kobinger, Gary; Bolay, Fatorma K; Zoon, Kathryn C; Stassijns, Jorgen; Giuliani, Ruggero; de Smet, Martin; Nichol, Stuart T; Fields, Barry; Sprecher, Armand; Massaquoi, Moses; Feldmann, Heinz; de Wit, Emmie

2016-10-15

The ongoing Ebola outbreak in West Africa has resulted in 28 646 suspected, probable, and confirmed Ebola virus infections. Nevertheless, malaria remains a large public health burden in the region affected by the outbreak. A joint Centers for Disease Control and Prevention/National Institutes of Health diagnostic laboratory was established in Monrovia, Liberia, in August 2014, to provide laboratory diagnostics for Ebola virus. All blood samples from suspected Ebola virus-infected patients admitted to the Médecins Sans Frontières ELWA3 Ebola treatment unit in Monrovia were tested by quantitative real-time polymerase chain reaction for the presence of Ebola virus and Plasmodium species RNA. Clinical outcome in laboratory-confirmed Ebola virus-infected patients was analyzed as a function of age, sex, Ebola viremia, and Plasmodium species parasitemia. The case fatality rate of 1182 patients with laboratory-confirmed Ebola virus infections was 52%. The probability of surviving decreased with increasing age and decreased with increasing Ebola viral load. Ebola virus-infected patients were 20% more likely to survive when Plasmodium species parasitemia was detected, even after controlling for Ebola viral load and age; those with the highest levels of parasitemia had a survival rate of 83%. This effect was independent of treatment with antimalarials, as this was provided to all patients. Moreover, treatment with antimalarials did not affect survival in the Ebola virus mouse model. Plasmodium species parasitemia is associated with an increase in the probability of surviving Ebola virus infection. More research is needed to understand the molecular mechanism underlying this remarkable phenomenon and translate it into treatment options for Ebola virus infection. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Plasmodium Parasitemia Associated With Increased Survival in Ebola Virus–Infected Patients

PubMed Central

Rosenke, Kyle; Adjemian, Jennifer; Munster, Vincent J.; Marzi, Andrea; Falzarano, Darryl; Onyango, Clayton O.; Ochieng, Melvin; Juma, Bonventure; Fischer, Robert J.; Prescott, Joseph B.; Safronetz, David; Omballa, Victor; Owuor, Collins; Hoenen, Thomas; Groseth, Allison; Martellaro, Cynthia; van Doremalen, Neeltje; Zemtsova, Galina; Self, Joshua; Bushmaker, Trenton; McNally, Kristin; Rowe, Thomas; Emery, Shannon L.; Feldmann, Friederike; Williamson, Brandi N.; Best, Sonja M.; Nyenswah, Tolbert G.; Grolla, Allen; Strong, James E.; Kobinger, Gary; Bolay, Fatorma K.; Zoon, Kathryn C.; Stassijns, Jorgen; Giuliani, Ruggero; de Smet, Martin; Nichol, Stuart T.; Fields, Barry; Sprecher, Armand; Massaquoi, Moses; Feldmann, Heinz; de Wit, Emmie

2016-01-01

Background. The ongoing Ebola outbreak in West Africa has resulted in 28 646 suspected, probable, and confirmed Ebola virus infections. Nevertheless, malaria remains a large public health burden in the region affected by the outbreak. A joint Centers for Disease Control and Prevention/National Institutes of Health diagnostic laboratory was established in Monrovia, Liberia, in August 2014, to provide laboratory diagnostics for Ebola virus. Methods. All blood samples from suspected Ebola virus–infected patients admitted to the Médecins Sans Frontières ELWA3 Ebola treatment unit in Monrovia were tested by quantitative real-time polymerase chain reaction for the presence of Ebola virus and Plasmodium species RNA. Clinical outcome in laboratory-confirmed Ebola virus–infected patients was analyzed as a function of age, sex, Ebola viremia, and Plasmodium species parasitemia. Results. The case fatality rate of 1182 patients with laboratory-confirmed Ebola virus infections was 52%. The probability of surviving decreased with increasing age and decreased with increasing Ebola viral load. Ebola virus–infected patients were 20% more likely to survive when Plasmodium species parasitemia was detected, even after controlling for Ebola viral load and age; those with the highest levels of parasitemia had a survival rate of 83%. This effect was independent of treatment with antimalarials, as this was provided to all patients. Moreover, treatment with antimalarials did not affect survival in the Ebola virus mouse model. Conclusions. Plasmodium species parasitemia is associated with an increase in the probability of surviving Ebola virus infection. More research is needed to understand the molecular mechanism underlying this remarkable phenomenon and translate it into treatment options for Ebola virus infection. PMID:27531847

Deciphering the key residues in Plasmodium falciparum beta-ketoacyl acyl carrier protein reductase responsible for interactions with Plasmodium falciparum acyl carrier protein.

PubMed

Karmodiya, Krishanpal; Modak, Rahul; Sahoo, Nirakar; Sajad, Syed; Surolia, Namita

2008-10-01

The type II fatty acid synthase (FAS) pathway of Plasmodium falciparum is a validated unique target for developing novel antimalarials, due to its intrinsic differences from the typeI pathway operating in humans. beta-Ketoacyl acyl carrier protein (ACP) reductase (FabG) performs the NADPH-dependent reduction of beta-ketoacyl-ACP to beta-hydroxyacyl-ACP, the first reductive step in the elongation cycle of fatty acid biosynthesis. In this article, we report intensive studies on the direct interactions of Plasmodium FabG and Plasmodium ACP in solution, in the presence and absence of its cofactor, NADPH, by monitoring the change in intrinsic fluorescence of P.falciparum FabG (PfFabG) and by surface plasmon resonance. To address the issue of the importance of the residues involved in strong, specific and stoichiometric binding of PfFabG to P.falciparum ACP (PfACP), we mutated Arg187, Arg190 and Arg230 of PfFabG. The activities of the mutants were assessed using both an ACP-dependent and an ACP-independent assay. The affinities of all the PfFabG mutants for acetoacetyl-ACP (the physiological substrate) were reduced to different extents as compared to wild-type PfFabG, but were equally active in biochemical assays with the substrate analog acetoacetyl-CoA. Kinetic analysis and studies of direct binding between PfFabG and PfACP confirmed the identification of Arg187 and Arg230 as critical residues for the PfFabG-PfACP interactions. Our studies thus reveal the significance of the positively charged/hydrophobic patch located adjacent to the active site cavities of PfFabG for interactions with PfACP.

The Relative Contribution of Symptomatic and Asymptomatic Plasmodium vivax and Plasmodium falciparum Infections to the Infectious Reservoir in a Low-Endemic Setting in Ethiopia.

PubMed

Tadesse, Fitsum G; Slater, Hannah C; Chali, Wakweya; Teelen, Karina; Lanke, Kjerstin; Belachew, Mulualem; Menberu, Temesgen; Shumie, Girma; Shitaye, Getasew; Okell, Lucy C; Graumans, Wouter; van Gemert, Geert-Jan; Kedir, Soriya; Tesfaye, Addisu; Belachew, Feleke; Abebe, Wake; Mamo, Hassen; Sauerwein, Robert; Balcha, Taye; Aseffa, Abraham; Yewhalaw, Delenasaw; Gadisa, Endalamaw; Drakeley, Chris; Bousema, Teun

2018-06-01

The majority of Plasmodium vivax and Plasmodium falciparum infections in low-endemic settings are asymptomatic. The relative contribution to the infectious reservoir of these infections compared to clinical malaria cases is currently unknown. We assessed infectivity of passively recruited symptomatic malaria patients (n = 41) and community-recruited asymptomatic individuals with microscopy-detected (n = 41) and polymerase chain reaction (PCR)-detected infections (n = 82) using membrane feeding assays with Anopheles arabiensis mosquitoes in Adama, Ethiopia. Malaria incidence and prevalence data were used to estimate the contributions of these populations to the infectious reservoir. Overall, 34.9% (29/83) of P. vivax- and 15.1% (8/53) P. falciparum-infected individuals infected ≥1 mosquitoes. Mosquito infection rates were strongly correlated with asexual parasite density for P. vivax (ρ = 0.63; P < .001) but not for P. falciparum (ρ = 0.06; P = .770). Plasmodium vivax symptomatic infections were more infectious to mosquitoes (infecting 46.5% of mosquitoes, 307/660) compared to asymptomatic microscopy-detected (infecting 12.0% of mosquitoes, 80/667; P = .005) and PCR-detected infections (infecting 0.8% of mosquitoes, 6/744; P < .001). Adjusting for population prevalence, symptomatic, asymptomatic microscopy-detected, and PCR-detected infections were responsible for 8.0%, 76.2%, and 15.8% of the infectious reservoir for P. vivax, respectively. For P. falciparum, mosquito infections were sparser and also predominantly from asymptomatic infections. In this low-endemic setting aiming for malaria elimination, asymptomatic infections were highly prevalent and responsible for the majority of onward mosquito infections. The early identification and treatment of asymptomatic infections might accelerate elimination efforts.

A tutorial of diverse genome analysis tools found in the CoGe web-platform using Plasmodium spp. as a model

PubMed Central

Castillo, Andreina I; Nelson, Andrew D L; Haug-Baltzell, Asher K; Lyons, Eric

2018-01-01

Abstract Integrated platforms for storage, management, analysis and sharing of large quantities of omics data have become fundamental to comparative genomics. CoGe (https://genomevolution.org/coge/) is an online platform designed to manage and study genomic data, enabling both data- and hypothesis-driven comparative genomics. CoGe’s tools and resources can be used to organize and analyse both publicly available and private genomic data from any species. Here, we demonstrate the capabilities of CoGe through three example workflows using 17 Plasmodium genomes as a model. Plasmodium genomes present unique challenges for comparative genomics due to their rapidly evolving and highly variable genomic AT/GC content. These example workflows are intended to serve as templates to help guide researchers who would like to use CoGe to examine diverse aspects of genome evolution. In the first workflow, trends in genome composition and amino acid usage are explored. In the second, changes in genome structure and the distribution of synonymous (Ks) and non-synonymous (Kn) substitution values are evaluated across species with different levels of evolutionary relatedness. In the third workflow, microsyntenic analyses of multigene families’ genomic organization are conducted using two Plasmodium-specific gene families—serine repeat antigen, and cytoadherence-linked asexual gene—as models. In general, these example workflows show how to achieve quick, reproducible and shareable results using the CoGe platform. We were able to replicate previously published results, as well as leverage CoGe’s tools and resources to gain additional insight into various aspects of Plasmodium genome evolution. Our results highlight the usefulness of the CoGe platform, particularly in understanding complex features of genome evolution. Database URL: https://genomevolution.org/coge/

Comparison of the diagnostic performance of microscopic examination with nested polymerase chain reaction for optimum malaria diagnosis in Upper Myanmar.

PubMed

Kang, Jung-Mi; Cho, Pyo-Yun; Moe, Mya; Lee, Jinyoung; Jun, Hojong; Lee, Hyeong-Woo; Ahn, Seong Kyu; Kim, Tae Im; Pak, Jhang Ho; Myint, Moe Kyaw; Lin, Khin; Kim, Tong-Soo; Na, Byoung-Kuk

2017-03-16

Accurate diagnosis of Plasmodium infection is crucial for prompt malaria treatment and surveillance. Microscopic examination has been widely applied as the gold standard for malaria diagnosis in most part of malaria endemic areas, but its diagnostic value has been questioned, particularly in submicroscopic malaria. In this study, the diagnostic performance of microscopic examination and nested polymerase chain reaction (PCR) was evaluated to establish optimal malaria diagnosis method in Myanmar. A total of 1125 blood samples collected from residents in the villages and towns located in Naung Cho, Pyin Oo Lwin, Tha Beik Kyin townships and Mandalay of Upper Myanmar were screened by microscopic examination and species-specific nested PCR method. Among the 1125 blood samples, 261 samples were confirmed to be infected with malaria by microscopic examination. Evaluation of the 1125 samples by species-specific nested PCR analysis revealed that the agreement between microscopic examination and nested PCR was 87.3% (261/299). Nested PCR successfully detected 38 Plasmodium falciparum or Plasmodium vivax infections, which were missed in microscopic examination. Microscopic examinations also either misdiagnosed the infected Plasmodium species, or did not detect mixed infections with different Plasmodium species in 31 cases. The nested PCR method is more reliable than conventional microscopic examination for the diagnosis of malaria infections, and this is particularly true in cases of mixed infections and submicroscopic infections. Given the observed higher sensitivity and specificity of nested PCR, the molecular method holds enormous promise in malaria diagnosis and species differentiation, and can be applied as an effective monitoring tool for malaria surveillance, control and elimination in Myanmar.

In vivo imaging in NHP models of malaria: challenges, progress and outlooks.

PubMed

Beignon, Anne-Sophie; Le Grand, Roger; Chapon, Catherine

2014-02-01

Animal models of malaria, mainly mice, have made a large contribution to our knowledge of host-pathogen interactions and immune responses, and to drug and vaccine design. Non-human primate (NHP) models for malaria are admittedly under-used, although they are probably closer models than mice for human malaria; in particular, NHP models allow the use of human pathogens (Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi). NHPs, whether natural hosts or experimentally challenged with a simian Plasmodium, can also serve as robust pre-clinical models. Some simian parasites are closely related to a human counterpart, with which they may share a common ancestor, and display similar major features with the human infection and pathology. NHP models allow longitudinal studies, from the early events following sporozoite inoculation to the later events, including analysis of organs and tissues, particularly liver, spleen, brain and bone marrow. NHP models have one other significant advantage over mouse models: NHPs are our closest relatives and thus their biology is very similar to ours. Recently developed in vivo imaging tools have provided insight into malaria parasite infection and disease in mouse models. One advantage of these tools is that they limit the need for invasive procedures, such as tissue biopsies. Many such technologies are now available for NHP studies and provide new opportunities for elucidating host/parasite interactions. The aim of this review is to bring the malaria community up to date on what is currently possible and what soon will be, in terms of in vivo imaging in NHP models of malaria, to consider the pros and the cons of the various techniques, and to identify challenges. © 2013.

Immunochromatographic antigen testing alone is sufficient to identify asymptomatic refugees at risk of severe malaria presenting to a single health service in Victoria.

PubMed

Fedele, Pasquale L; Wheeler, Michael; Lemoh, Christopher; Chunilal, Sanjeev

2014-10-01

Current screening guidelines for malaria in new refugees include a combination of thick and thin film examination and immunochromatographic antigen test (ICT). However, as the prevalence of malaria in our population has decreased due to changing refugee demographics, we sought to determine if an ICT alone can reliably exclude malaria in our asymptomatic refugee population.A retrospective analysis was conducted of all investigations for malaria performed from 1 August 2011 to 31 July 2013, including thick and thin blood film examination, BinaxNOW ICT, and external morphological and polymerase chain reaction (PCR) validation where applicable.Malaria was diagnosed in 45 of 1248 (3.6%) patients investigated, all of whom were symptomatic and the majority (71.1%) returned travellers. All 599 asymptomatic refugees screened were negative. Overall, 42 of 45 malaria cases were detected by the ICT; sensitivity 93.3% (95% CI 80.7-98.3%) and negative predictive value (NPV) 99.8% (99.2-99.9%). All 21 cases of Plasmodium falciparum and 20 of 22 cases of Plasmodium vivax were detected, giving a sensitivity of 100% (80.8-100%) and 90.9% (69.4-98.4%) respectively. Too few cases of Plasmodium malariae and no cases of Plasmodium ovale or Plasmodium knowlesi were diagnosed for adequate assessment to be carried out.These data suggest that full malaria screening in all asymptomatic refugees with the combination of thick and thin blood films and rapid antigen test may not be warranted. Alternative screening approaches should be considered, including the use of ICT alone, or limiting screening of asymptomatic refugees to only those originating from countries with high incidence of malaria.

Performance of a new gelled nested PCR test for the diagnosis of imported malaria: comparison with microscopy, rapid diagnostic test, and real-time PCR.

PubMed

Iglesias, Nuria; Subirats, Mercedes; Trevisi, Patricia; Ramírez-Olivencia, Germán; Castán, Pablo; Puente, Sabino; Toro, Carlos

2014-07-01

Microscopy and rapid diagnostic tests (RDTs) are the techniques commonly used for malaria diagnosis but they are usually insensitive at very low levels of parasitemia. Nested PCR is commonly used as a reference technique in the diagnosis of malaria due to its high sensitivity and specificity. However, it is a cumbersome assay only available in reference centers. We evaluated a new nested PCR-based assay, BIOMALAR kit (Biotools B&M Labs, Madrid, Spain) which employs ready-to-use gelled reagents and allows the identification of the main four species of Plasmodium. Blood samples were obtained from patients with clinical suspicion of malaria. A total of 94 subjects were studied. Fifty-two (55.3%) of them were malaria-infected subjects corresponding to 48 cases of Plasmodium falciparum, 1 Plasmodium malariae, 2 Plasmodium vivax, and 1 Plasmodium ovale. The performance of the BIOMALAR test was compared with microscopy, rapid diagnostic test (RDT) (BinaxNOW® Malaria) and real-time quantitative PCR (qPCR). The BIOMALAR test showed a sensitivity of 98.1% (95% confidence interval [CI], 89.7-100), superior to microscopy (82.7% [95% CI, 69.7-91.8]) and RDT (94.2% [95% CI, 84.1-98.8]) and similar to qPCR (100% [95% CI, 93.2-100]). In terms of specificity, the BIOMALAR assay showed the same value as microscopy and qPCR (100% [95% CI, 93.2-100]). Nine subjects were submicroscopic carriers of malaria. The BIOMALAR test identified almost all of them (8/9) in comparison with RDT (6/9) and microscopy (0/9). In conclusion, the BIOMALAR is a PCR-based assay easy to use with an excellent performance and especially useful for diagnosis submicroscopic malaria.

G6PD deficiency in Plasmodium falciparum and Plasmodium vivax malaria-infected Cambodian patients.

PubMed

Khim, Nimol; Benedet, Christophe; Kim, Saorin; Kheng, Sim; Siv, Sovannaroth; Leang, Rithea; Lek, Soley; Muth, Sinuon; Chea, Nguon; Chuor, Char Meng; Duong, Socheat; Kerleguer, Alexandra; Tor, Pety; Chim, Pheaktra; Canier, Lydie; Witkowski, Benoit; Taylor, Walter R J; Ménard, Didier

2013-05-28

Glucose-6-phosphate-dehydrogenase deficiency (G6PDd) rates are unknown in malaria-infected Cambodian patients. These data are key to a rational drug policy for malaria elimination of Plasmodium falciparum and Plasmodium vivax. From September 2010-2012, a two-year survey of G6PDd and haemoglobinopathies assessed by quantitative enzyme activity assay and haemoglobin electrophoresis, respectively, was conducted in malaria-infected patients presenting to 19 health centres throughout Cambodia. A total of 2,408 confirmed malaria patients of mean age 26.7 (range 2-81) years were recruited from mostly western Cambodia (n = 1,732, 71.9%); males outnumbered females by 3.9:1. Plasmodium falciparum was present in 1,443 (59.9%) and P. vivax in 965 (40.1%) patients. Mean G6PD activity was 11.6 (CI 95%: 11.4-11.8) U/g Hb, G6PDd was present in 13.9% of all patients (335/2,408) and severe G6PDd (including WHO Class I and II variants) was more common in western (158/1,732, 9.1%) versus eastern (21/414, 5.1%) Cambodia (P = 0.01). Of 997/2,408 (41.4%) had a haemoglobinopathy. Mean haemoglobin concentrations were inversely related to age: 8.1 g/dL < five years, 8.7 g/dL five to 14 years, and 10.4 g/dL >15 years (P <0.001). G6PDd prevalence, anaemia and haemoglobinopathies were common in malaria-infected patients. The deployment of primaquine in Cambodia should be preceded by primaquine safety studies paralleled with evaluations of easy to use tests to detect G6PDd.

G6PD deficiency in Plasmodium falciparum and Plasmodium vivax malaria-infected Cambodian patients

PubMed Central

2013-01-01

Background Glucose-6-phosphate-dehydrogenase deficiency (G6PDd) rates are unknown in malaria-infected Cambodian patients. These data are key to a rational drug policy for malaria elimination of Plasmodium falciparum and Plasmodium vivax. Methods From September 2010–2012, a two-year survey of G6PDd and haemoglobinopathies assessed by quantitative enzyme activity assay and haemoglobin electrophoresis, respectively, was conducted in malaria-infected patients presenting to 19 health centres throughout Cambodia. Results A total of 2,408 confirmed malaria patients of mean age 26.7 (range 2–81) years were recruited from mostly western Cambodia (n = 1,732, 71.9%); males outnumbered females by 3.9:1. Plasmodium falciparum was present in 1,443 (59.9%) and P. vivax in 965 (40.1%) patients. Mean G6PD activity was 11.6 (CI 95%: 11.4-11.8) U/g Hb, G6PDd was present in 13.9% of all patients (335/2,408) and severe G6PDd (including WHO Class I and II variants) was more common in western (158/1,732, 9.1%) versus eastern (21/414, 5.1%) Cambodia (P = 0.01). Of 997/2,408 (41.4%) had a haemoglobinopathy. Mean haemoglobin concentrations were inversely related to age: 8.1 g/dL < five years, 8.7 g/dL five to 14 years, and 10.4 g/dL >15 years (P <0.001). Conclusions G6PDd prevalence, anaemia and haemoglobinopathies were common in malaria-infected patients. The deployment of primaquine in Cambodia should be preceded by primaquine safety studies paralleled with evaluations of easy to use tests to detect G6PDd. PMID:23714236

High Plasmodium malariae Prevalence in an Endemic Area of the Colombian Amazon Region.

PubMed

Camargo-Ayala, Paola Andrea; Cubides, Juan Ricardo; Niño, Carlos Hernando; Camargo, Milena; Rodríguez-Celis, Carlos Arturo; Quiñones, Teódulo; Sánchez-Suárez, Lizeth; Patarroyo, Manuel Elkin; Patarroyo, Manuel Alfonso

2016-01-01

Malaria is a worldwide public health problem; parasites from the genus Plasmodium are the aetiological agent for this disease. The parasites are mostly diagnosed by conventional microscopy-based techniques; however, their limitations have led to under-registering the reported prevalence of Plasmodium species. This study has thus been aimed at evaluating the infection and coinfection prevalence of 3 species of Plasmodium spp., in an area of the Colombian Amazon region. Blood samples were taken from 671 symptomatic patients by skin puncture; a nested PCR amplifying the 18S ssRNA region was used on all samples to determine the presence of P. vivax, P. malariae and P. falciparum. Statistical analysis determined infection and coinfection frequency; the association between infection and different factors was established. The results showed that P. vivax was the species having the greatest frequency in the study population (61.4%), followed by P. malariae (43.8%) and P. falciparum (11.8%). The study revealed that 35.8% of the population had coinfection, the P. vivax/P. malariae combination occurring most frequently (28.3%); factors such as age, geographical origin and clinical manifestations were found to be associated with triple-infection. The prevalence reported in this study differed from previous studies in Colombia; the results suggest that diagnosis using conventional techniques could be giving rise to underestimating some Plasmodium spp. species having high circulation rates in Colombia (particularly in the Colombian Amazon region). The present study's results revealed a high prevalence of P. malariae and mixed infections in the population being studied. The results provide relevant information which should facilitate updating the epidemiological panorama and species' distribution so as to include control, prevention and follow-up measures.

Effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria in outbreak prone districts of Rajasthan, India.

PubMed

Lingala, Mercy A L

Malaria is a public health problem caused by Plasmodium parasite and transmitted by anopheline mosquitoes. Arid and semi-arid regions of western India are prone to malaria outbreaks. Malaria outbreak prone districts viz. Bikaner, Barmer and Jodhpur were selected to study the effect of meteorological variables on Plasmodium vivax and Plasmodium falciparum malaria outbreaks for the period of 2009-2012. The data of monthly malaria cases and meteorological variables was analysed using SPSS 20v. Spearman correlation analysis was conducted to examine the strength of the relationship between meteorological variables, P. vivax and P. falciparum malaria cases. Pearson's correlation analysis was carried out among the meteorological variables to observe the independent effect of each independent variable on the outcome. Results indicate that malaria outbreaks have occurred in Bikaner and Barmer due to continuous rains for more than two months. Rainfall has shown to be an important predictor of malaria outbreaks in Rajasthan. P. vivax is more significantly correlated with rainfall, minimum temperature (P<0.01) and less significantly with relative humidity (P<0.05); whereas P. falciparum is significantly correlated with rainfall, relative humidity (P<0.01) and less significantly with temperature (P<0.05). The determination of the lag period for P. vivax is relative humidity and for P. falciparum is temperature. The lag period between malaria cases and rainfall is shorter for P. vivax than P. falciparum. In conclusion, the knowledge generated is not only useful to take prompt malaria control interventions but also helpful to develop better forecasting model in outbreak prone regions. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Structural modeling identifies Plasmodium vivax 4-diphosphocytidyl-2C-methyl-d-erythritol kinase (IspE) as a plausible new antimalarial drug target.

PubMed

Kadian, Kavita; Vijay, Sonam; Gupta, Yash; Rawal, Ritu; Singh, Jagbir; Anvikar, Anup; Pande, Veena; Sharma, Arun

2018-08-01

Malaria parasites utilize Methylerythritol phosphate (MEP) pathway for synthesis of isoprenoid precursors which are essential for maturation and survival of parasites during erythrocytic and gametocytic stages. The absence of MEP pathway in the human host establishes MEP pathway enzymes as a repertoire of essential drug targets. The fourth enzyme, 4-diphosphocytidyl-2C-methyl-d-erythritol kinase (IspE) has been proved essential in pathogenic bacteria, however; it has not yet been studied in any Plasmodium species. This study was undertaken to investigate genetic polymorphism and concomitant structural implications of the Plasmodium vivax IspE (PvIspE) by employing sequencing, modeling and bioinformatics approach. We report that PvIspE gene displayed six non-synonymous mutations which were restricted to non-conserved regions within the gene from seven topographically distinct malaria-endemic regions of India. Phylogenetic studies reflected that PvIspE occupies unique status within Plasmodia genus and reflects that Plasmodium vivax IspE gene has a distant and non-conserved relation with human ortholog Mevalonate Kinase (MAVK). Structural modeling analysis revealed that all PvIspE Indian isolates have critically conserved canonical galacto-homoserine-mevalonate-phosphomevalonate kinase (GHMP) domain within the active site lying in a deep cleft sandwiched between ATP and CDPME-binding domains. The active core region was highly conserved among all clinical isolates, may be due to >60% β-pleated rigid architecture. The mapped structural analysis revealed the critically conserved active site of PvIspE, both sequence, and spacially among all Indian isolates; showing no significant changes in the active site. Our study strengthens the candidature of Plasmodium vivax IspE enzyme as a future target for novel antimalarials. Copyright © 2018 Elsevier B.V. All rights reserved.

Nest ecology of blood parasites in the European roller and its ectoparasitic carnid fly.

PubMed

Václav, Radovan; Betáková, Tatiana; Švančarová, Petra; Pérez-Serrano, Jorge; Criado-Fornelio, Ángel; Škorvanová, Lucia; Valera, Francisco

2016-06-01

Haemosporidian parasites are considered the most important vector-borne parasites. However, vector identity and ecology is unknown for most such host-vector-parasite systems. In this study, we employ microscopic and molecular analyses to examine haemosporidian prevalence in a migratory, cavity-nesting bird, European roller Coracias garrulus, and its nidicolous blood-feeding ectoparasite Carnus hemapterus. This system is unique in that the ectoparasite is confined to a near-closed environment, in contrast to the free-wandering system of haematophagous dipterans such as mosquitoes. Blood film analysis confirms previous works in that Haemoproteus parasites are widely prevalent in adult rollers and belong to a single species, Haemoproteus coraciae. Leucocytozoon sp. and Trypanosoma sp. also are detected in adult rollers at low intensities with this technique. By means of molecular analysis, we report for the first time Plasmodium sp. presence in C. garrulus. Based on PCR results, Plasmodium parasites are relatively less prevalent than Haemoproteus parasites (20% vs. 31%) in rollers. In contrast, haemosporidian prevalences show the opposite trend for Carnus flies: Plasmodium sp. occurrence (62%) clearly predominates over that of Haemoproteus sp. (5%). A comparison between roller and Carnus samples reveals a significantly higher prevalence of Plasmodium sp. in Carnus samples. Insect survey and phylogenetic analysis suggest Culicoides flies as Haemoproteus sp. vectors, which appear to readily transmit the parasite in southern Spain. This study does not find support for Carnus flies to serve as biological or mechanical vectors of haemosporidians. In spite of this, nidicolous blood-feeding ectoparasites, such as carnid flies, appear as a suitable model for studies on the occurrence and temporal dynamics of avian haemosporidians such as Plasmodium sp. present at low intensities. Copyright © 2016 Elsevier Inc. All rights reserved.

Genetic variants related to disease susceptibility and immunotolerance in the Duffy antigen receptor for chemokines (DARC, Fy) gene in the black lion tamarin (Leontopithecus chrysopygus, primates).

PubMed

Ansel, Ashley; Lewis, James D; Melnick, Don J; Martins, Cristiana; Valladares-Padua, Claudio; Perez-Sweeney, Beatriz

2017-10-01

The DARC (Duffy antigen receptor for chemokines) gene encodes the DARC protein, which serves multiple roles in the immune system, as a binding site for the malarial parasites Plasmodium vivax and Plasmodium knowlesi, a promiscuous chemokine receptor and a blood group antigen. Variation in DARC may play particularly significant roles in innate immunity, immunotolerance and pathogen entry in callitrichines, such as the black lion tamarin (Leontopithecus chrysopygus). We compared amino acid sequences of DARC in the black lion tamarin (BLT) to non-human Haplorhine primates and Homo sapiens. Consistent with prior studies in other Haplorhines, we observed that the chemokine receptor experiences two opposing selection forces: (1) positive selection on the Plasmodium binding site and (2) purifying selection. We observed also that D21N, F22L, and V25L differentiated BLT from humans at a critical site for P. vivax and P. knowlesi binding. One amino acid residue, F22L, was subject to both positive selection and fixation in New World monkeys, suggesting a beneficial role as an adaptive barrier to Plasmodium entry. Unlike in humans, we observed no variation in DARC among BLTs, suggesting that the protein does not play a role in immunotolerance. In addition, lion tamarins differed from humans at the blood compatibility Fy a /Fy b antigen-binding site 44, as well as at the putative destabilizing residues A61, T68, A187, and L215, further supporting a difference in the functional role of DARC in these primates compared with humans. Further research is needed to determine whether changes in the Plasmodium and Fy a /Fy b antigen-binding sites disrupt DARC function in callitrichines. © 2017 Wiley Periodicals, Inc.

Natural History of Plasmodium odocoilei Malaria Infection in Farmed White-Tailed Deer.

PubMed

Guggisberg, Ann M; Sayler, Katherine A; Wisely, Samantha M; Odom John, Audrey R

2018-04-25

White-tailed deer ( Odocoileus virginianus ), an ecologically and economically important species, are the most widely distributed large animals in North America. A recent study indicated that up to 25% of all white-tailed deer may be infected with Plasmodium odocoilei , a malaria parasite belonging to the distinct clade of ungulate-infecting Plasmodium spp. Because the clinical impact of P. odocoilei on deer health and survival is unknown, we undertook a retrospective longitudinal study of farmed Floridian O. virginianus fawns. We found that a substantial proportion (21%) of fawns acquire malaria infection during the first 8 months of life. Some animals naturally clear P. odocoilei infection, while other animals remain persistently positive. Importantly, we found that animals that acquire malaria parasites very early in life have poor survival compared to animals that remain uninfected. Our report thus provides the first evidence of a clinically significant impact of malaria infection in young deer. IMPORTANCE Malaria parasites of the genus Plasmodium are known to infect a variety of vertebrate hosts, including ungulates (hoofed mammals). A recent study found that up to a quarter of white-tailed deer ( Odocoileus virginianus ) in North America are infected with the parasite Plasmodium odocoilei In addition to occupying an important ecological niche, white-tailed deer are popular game animals and deer farming represents a rapidly growing industry. However, the effect of P. odocoilei infection in this ecologically and economically important ungulate species is unknown. Our work is significant because (i) we identified a high prevalence of P. odocoilei in farmed deer and (ii) we found evidence for both cleared and persistent infection, as well as an association with decreased survival of young fawns. Copyright © 2018 Guggisberg et al.

Vitamin and co-factor biosynthesis pathways in Plasmodium and other apicomplexan parasites

PubMed Central

Müller, Sylke; Kappes, Barbara

2007-01-01

Vitamins are essential components of the human diet. By contrast, the malaria parasite Plasmodium falciparum and related apicomplexan parasites synthesise certain vitamins, de novo, either completely or in parts. The occurrence of the various biosynthesis pathways is specific to different apicomplexan parasites, emphasising their distinct requirements for nutrients and growth factors. The absence of vitamin biosynthesis from the human host implies that inhibition of the parasite pathways may be a way to interfere specifically with parasite development. However, the precise role of biosynthesis and potential uptake of vitamins for the overall regulation of vitamin homeostasis in the parasites needs to be established first. In this review Sylke Müller and Barbara Kappes focus mainly on the procurement of vitamin B1, B5 and B6 by Plasmodium and other apicomplexan parasites. PMID:17276140

Synthesis of chiral chloroquine and its analogues as antimalarial agents.

PubMed

Sinha, Manish; Dola, Vasanth R; Soni, Awakash; Agarwal, Pooja; Srivastava, Kumkum; Haq, Wahajul; Puri, Sunil K; Katti, Seturam B

2014-11-01

In this investigation, we describe a new approach to chiral synthesis of chloroquine and its analogues. All tested compounds displayed potent activity against chloroquine sensitive as well as chloroquine resistant strains of Plasmodium falciparum in vitro and Plasmodium yoelii in vivo. Compounds S-13 b, S-13c, S-13 d and S-13 i displayed excellent in vitro antimalarial activity with an IC50 value of 56.82, 60.41, 21.82 and 7.94 nM, respectively, in the case of resistant strain. Furthermore, compounds S-13a, S-13c and S-13 d showed in vivo suppression of 100% parasitaemia on day 4 in the mouse model against Plasmodium yoelii when administered orally. These results underscore the application of synthetic methodology and need for further lead optimization. Copyright © 2014 Elsevier Ltd. All rights reserved.

Platelet Factor 4 Mediates Inflammation in Cerebral Malaria

PubMed Central

Srivastava, Kalyan; Cockburn, Ian A.; Swaim, AnneMarie; Thompson, Laura E.; Tripathi, Abhai; Fletcher, Craig A.; Shirk, Erin M.; Sun, Henry; Kowalska, M. Anna; Fox-Talbot, Karen; Sullivan, David; Zavala, Fidel; Morrell, Craig N.

2008-01-01

Summary Cerebral malaria is a major complication of Plasmodium falciparum infection in children. The pathogenesis of cerebral malaria involves vascular inflammation, immune stimulation and obstruction of cerebral capillaries. Platelets have a prominent role in both immune responses and vascular obstruction. We now demonstrate that the platelet derived chemokine, platelet factor 4 (PF4)/CXCL4, promotes the development of experimental cerebral malaria. Plasmodium infected red blood cells (RBC) activated platelets independent of vascular effects, resulting in increased plasma PF4. PF4 or CXCR3 null mice had less ECM, decreased brain T-cell recruitment, and platelet depletion or aspirin treatment reduced the development of ECM. We conclude that Plasmodium infected RBC can activate platelets and platelet derived PF4 then contributes to immune activation and T-cell trafficking as part of the pathogenesis of ECM. PMID:18692777

Malaria vaccines: high-throughput tools for antigens discovery with potential for their development

PubMed Central

Céspedes, Nora; Vallejo, Andrés; Arévalo-Herrera, Myriam

2013-01-01

Malaria is a disease induced by parasites of the Plasmodium genus, which are transmitted by Anopheles mosquitoes and represents a great socio-economic burden Worldwide. Plasmodium vivax is the second species of malaria Worldwide, but it is the most prevalent in Latin America and other regions of the planet. It is currently considered that vaccines represent a cost-effective strategy for controlling transmissible diseases and could complement other malaria control measures; however, the chemical and immunological complexity of the parasite has hindered development of effective vaccines. Recent availability of several genomes of Plasmodium species, as well as bioinformatic tools are allowing the selection of large numbers of proteins and analysis of their immune potential. Herein, we review recently developed strategies for discovery of novel antigens with potential for malaria vaccine development. PMID:24892459

Unidentified Plasmodium species in Australian black swans (Cygnus atratus) hatched and raised in North America.

PubMed

Grim, K Christiana; McCutchan, Thomas; Sullivan, Margery; Cranfield, Michael R

2008-06-01

A pair of Australian black swans (Cygnus atratus) with origins in Wakefield, Virginia, USA, was admitted to the quarantine area at the Baltimore Zoo for general health assessments before housing in the collections. During the quarantine period, no clinical signs of disease were manifest; however, upon examination of a blood smear, intraerythrocytic parasites were detected and initially determined to be Haemoproteus species. Diagnostic polymerase chain reaction (PCR) and sequencing results, however, indicated that the parasites were within the genus Plasmodium. Subclinical infections with Plasmodium species in birds may affect collection management, and transmission from refractory hosts to susceptible hosts should be considered when multispecies exhibits are used. In addition, changes in the dynamics of host-vector-parasite interactions might have significant impacts on wild or domesticated populations of birds.

Ape parasite origins of human malaria virulence genes

PubMed Central

Larremore, Daniel B.; Sundararaman, Sesh A.; Liu, Weimin; Proto, William R.; Clauset, Aaron; Loy, Dorothy E.; Speede, Sheri; Plenderleith, Lindsey J.; Sharp, Paul M.; Hahn, Beatrice H.; Rayner, Julian C.; Buckee, Caroline O.

2015-01-01

Antigens encoded by the var gene family are major virulence factors of the human malaria parasite Plasmodium falciparum, exhibiting enormous intra- and interstrain diversity. Here we use network analysis to show that var architecture and mosaicism are conserved at multiple levels across the Laverania subgenus, based on var-like sequences from eight single-species and three multi-species Plasmodium infections of wild-living or sanctuary African apes. Using select whole-genome amplification, we also find evidence of multi-domain var structure and synteny in Plasmodium gaboni, one of the ape Laverania species most distantly related to P. falciparum, as well as a new class of Duffy-binding-like domains. These findings indicate that the modular genetic architecture and sequence diversity underlying var-mediated host-parasite interactions evolved before the radiation of the Laverania subgenus, long before the emergence of P. falciparum. PMID:26456841

Density-dependent blood stage Plasmodium falciparum suppresses malaria super-infection in a malaria holoendemic population.

PubMed

Pinkevych, Mykola; Petravic, Janka; Chelimo, Kiprotich; Vulule, John; Kazura, James W; Moormann, Ann M; Davenport, Miles P

2013-11-01

Recent studies of Plasmodium berghei malaria in mice show that high blood-stage parasitemia levels inhibit the development of subsequent liver-stage infections. Whether a similar inhibitory effect on liver-stage Plasmodium falciparum by blood-stage infection occurs in humans is unknown. We have analyzed data from a treatment-time-to-infection cohort of children < 10 years of age residing in a malaria holoendemic area of Kenya where people experience a new blood-stage infection approximately every 2 weeks. We hypothesized that if high parasitemia blocked the liver stage, then high levels of parasitemia should be followed by a "skipped" peak of parasitemia. Statistical analysis of "natural infection" field data and stochastic simulation of infection dynamics show that the data are consistent with high P. falciparum parasitemia inhibiting liver-stage parasite development in humans.

The MB2 gene family of Plasmodium species has a unique combination of S1 and GTP-binding domains

PubMed Central

Romero, Lisa C; Nguyen, Thanh V; Deville, Benoit; Ogunjumo, Oluwasanmi; James, Anthony A

2004-01-01

Background Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing. Results Genes homologous to MB2 were identified in five additional parasite species, P. knowlesi, P. gallinaceum, P. berghei, P. yoelii, and P. chabaudi. Sequence comparisons among the MB2 gene products reveal amino acid conservation of structural features, including putative S1 and GTP-binding domains, and putative signal peptides and nuclear localization signals. Conclusions The combination of domains is unique to this gene family and indicates that MB2 genes comprise a novel family and therefore may be a good target for drug development. PMID:15222903

Plasmodium vivax Malaria in Cambodia

PubMed Central

Siv, Sovannaroth; Roca-Feltrer, Arantxa; Vinjamuri, Seshu Babu; Bouth, Denis Mey; Lek, Dysoley; Rashid, Mohammad Abdur; By, Ngau Peng; Popovici, Jean; Huy, Rekol; Menard, Didier

2016-01-01

The Cambodian National Strategic Plan for Elimination of Malaria aims to move step by step toward elimination of malaria across Cambodia with an initial focus on Plasmodium falciparum malaria before achieving elimination of all forms of malaria, including Plasmodium vivax in 2025. The emergence of artemisinin-resistant P. falciparum in western Cambodia over the last decade has drawn global attention to support the ultimate goal of P. falciparum elimination, whereas the control of P. vivax lags much behind, making the 2025 target gradually less achievable unless greater attention is given to P. vivax elimination in the country. The following review presents in detail the past and current situation regarding P. vivax malaria, activities of the National Malaria Control Program, and interventional measures applied. Constraints and obstacles that can jeopardize our efforts to eliminate this parasite species are discussed. PMID:27708187

Detection of anti-neutrophil cytoplasmic antibodies after acute Plasmodium falciparum malaria.

PubMed Central

Wenisch, C; Wenisch, H; Bankl, H C; Exner, M; Graninger, W; Looareesuwan, S; Rumpold, H

1996-01-01

Four of 30 patients with Plasmodium falciparum infection in Bangkok, Thailand, were positive for anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence 1 month after antimalarial therapy. No myeloperoxidase, proteinase 3, lactoferrin, or elastase reactivity was found. Since no evidence of vasculitis was seen in these patients, anti-neutrophil cytoplasmic antibody production in malaria-infected susceptible patients probably represents a secondary response, indicating neutrophil activation. PMID:8770517

Plasmodium knowlesi in humans: a review on the role of its vectors in Malaysia.

PubMed

Vythilingam, Indra

2010-04-01

Plasmodium knowlesi in humans is life threatening, is on the increase and has been reported from most states in Malaysia. Anopheles latens and Anopheles cracens have been incriminated as vectors. Malaria is now a zoonoses and is occurring in malaria free areas of Malaysia. It is also a threat to eco-tourism. The importance of the vectors and possible control measures is reviewed here.

Babesia bovis expresses Bbo-6cys-E, a member of a novel gene family that is homologous to the 6-cys family of Plasmodium

USDA-ARS?s Scientific Manuscript database

A novel Babesia bovis gene family encoding proteins with similarities to the Plasmodium 6cys protein family was identified by TBLASTN searches of the Babesia bovis genome using the sequence of the P. falciparum PFS230 protein as query, and was termed Bbo-6cys gene family. The Bbo-cys6 gene family co...

Subinoculation as a technique in the diagnosis of avian plasmodium

USGS Publications Warehouse

Herman, C.M.; Knisley, J.O.; Snyder, E.L.

1966-01-01

In two successive years, 1964 and 1965, blood subinoculated from wild Canada geese, negative for Plasmodium by examination of peripheral blood smears, into 5-day-old domestic geese produced 60 % infection in the recipients. Prepatent and patent periods, as well as intensity of parasitemia showed much variation. Intramuscular inoculation produced the same prevalence as the intravenous route, but longer prepatent periods and less intensity of parasitemia.

First autochthonous malaria case due to Plasmodium vivax since eradication, Spain, October 2010.

PubMed

Santa-Olalla Peralta, P; Vazquez-Torres, M C; Latorre-Fandos, E; Mairal-Claver, P; Cortina-Solano, P; Puy-Azón, A; Adiego Sancho, B; Leitmeyer, K; Lucientes-Curdi, J; Sierra-Moros, M J

2010-10-14

In October 2010, one case of autochthonous malaria due to Plasmodium vivax was diagnosed in Spain. The case occurred in Aragon, north-eastern Spain, where the vector Anopheles atroparvus is present. Although the source of infection could not be identified, this event highlights that sporadic autochthonous transmission of vector-borne diseases in continental Europe is possible and calls for enhanced surveillance and vector control measures.

Regional Disease Vector Ecology Profile: Caribbean

DTIC Science & Technology

2002-07-01

malaria is caused by any of 4 protozoan species in the genus Plasmodium that are transmitted by the bite of an infective female Anopheles mosquito... infected by many Plasmodium species that can infect humans, but natural transmission is rare. Female mosquitoes of the genus Anopheles are the...Most anophelines feed on exposed legs, although some may feed on arms, ears or the neck. Infected females tend to feed intermittently and thus may

Immune Responses and Protection of Aotus Monkeys Immunized with Irradiated Plasmodium vivax Sporozoites

DTIC Science & Technology

2011-01-01

The experimental protocol was approved by the Animal Ethical Committee of the Universidad del Valle (Cali). Parasite and irradiation. Plasmodium...three repeats ofpll (GDRADGPA) and (ANGAGNQPG) sequences, derived from VK210 and VK247 CS variants, respectively. A non-malaria related peptide Ptt30...Universidad del Valle and Centro Internacional de Vacunas, Cali, Colombia, E-mails: alejovi@hotmail.com, anbonelo@yahoo.com, alejcaste@yahoo.com

Role of mechanics in the appearance of oscillatory instability and standing waves of the mechanochemical activity in the Physarum polycephalum plasmodium

NASA Astrophysics Data System (ADS)

Teplov, Vladimir A.

2017-06-01

The modes of continuously distributed mechanochemical self-sustained oscillations (autowaves) exhibited by the Physarum plasmodium under different experimental conditions are reviewed. The role of the stretch-induced activation of contractile oscillations in the spatiotemporal self-organization of the plasmodium is elucidated. Different mathematical models describing contractile autowaves in ectoplasm and the streaming of the endoplasm are considered. Our mathematical models, which are based on the hypothesis of local positive feedback between the deformation and contraction of the contractile apparatus, are also presented. The feedback is mediated through a chemical regulatory system, whose kinetics involves the coupling to the mechanical strain. The mathematical analysis and computer simulations have demonstrated that the solutions of the models agree quantitatively with the experimental data. In particular, the only hydrodynamic interactions between the different parts of the plasmodium via the streaming endoplasm can lead to globally coordinated ectoplasmic contractions and vigorous shuttle endoplasmic streaming. These models, with empirically determined values of the viscoelastic parameters, well simulate the form and duration of the transient contractile processes observed after the isolation of the strands as well as the subsequent excitation of auto-oscillations and their stretch-induced activation under isotonic and isometric conditions.

Use of polymerase chain reaction technique to confirm VecTest screening results in Plasmodium falciparum and Plasmodium vivax VK 210 laboratory-infected Anopheles stephensi mosquitoes.

PubMed

Santos-Ciminera, Patricia D; Acheé, Nicole L; Quinnan, Gerald V; Roberts, Donald R

2004-09-01

We evaluated polymerase chain reaction (PCR) to confirm immunoassays for malaria parasites in mosquito pools after a failure to detect malaria with PCR during an outbreak in which pools tested positive using VecTest and enzyme-linked immunosorbent assay (ELISA). We combined VecTest, ELISA, and PCR to detect Plasmodium falciparum and Plasmodium vivax VK 210. Each mosquito pool, prepared in triplicate, consisted of 1 exposed Anopheles stephensi and up to 9 unfed mosquitoes. The results of VecTest and ELISA were concordant. DNA from a subset of the pools, 1 representative of each ratio of infected to uninfected mosquitoes, was extracted and used as template in PCR. All P. vivax pools were PCR positive but some needed additional processing for removal of apparent inhibitors before positive results were obtained. One of the pools selected for P. falciparum was negative by PCR, probably because of losses or contamination during DNA extraction; 2 remaining pools at this ratio were PCR positive. Testing pools by VecTest, ELISA, and PCR is feasible, and PCR is useful for confirmation of immunoassays. An additional step might be needed to remove potential inhibitors from pools prior to PCR.

Mhc supertypes confer both qualitative and quantitative resistance to avian malaria infections in a wild bird population

PubMed Central

Sepil, Irem; Lachish, Shelly; Hinks, Amy E.; Sheldon, Ben C.

2013-01-01

Major histocompatibility complex (Mhc) genes are believed to play a key role in the genetic basis of disease control. Although numerous studies have sought links between Mhc and disease prevalence, many have ignored the ecological and epidemiological aspects of the host–parasite interaction. Consequently, interpreting associations between prevalence and Mhc has been difficult, whereas discriminating alleles for qualitative resistance, quantitative resistance and susceptibility remains challenging. Moreover, most studies to date have quantified associations between genotypes and disease status, overlooking the complex relationship between genotype and the properties of the Mhc molecule that interacts with parasites. Here, we address these problems and demonstrate avian malaria (Plasmodium) parasite species-specific associations with functional properties of Mhc molecules (Mhc supertypes) in a wild great tit (Parus major) population. We further show that correctly interpreting these associations depends crucially on understanding the spatial variation in risk of infection and the fitness effects of infection. We report that a single Mhc supertype confers qualitative resistance to Plasmodium relictum, whereas a different Mhc supertype confers quantitative resistance to Plasmodium circumflexum infections. Furthermore, we demonstrate common functional properties of Plasmodium-resistance alleles in passerine birds, suggesting this is a model system for parasite–Mhc associations in the wild. PMID:23516242

The periodicity of Plasmodium vivax and Plasmodium falciparum in Venezuela.

PubMed

Grillet, María-Eugenia; El Souki, Mayida; Laguna, Francisco; León, José Rafael

2014-01-01

We investigated the periodicity of Plasmodium vivax and P. falciparum incidence in time-series of malaria data (1990-2010) from three endemic regions in Venezuela. In particular, we determined whether disease epidemics were related to local climate variability and regional climate anomalies such as the El Niño Southern Oscillation (ENSO). Malaria periodicity was found to exhibit unique features in each studied region. Significant multi-annual cycles of 2- to about 6-year periods were identified. The inter-annual variability of malaria cases was coherent with that of SSTs (ENSO), mainly at temporal scales within the 3-6 year periods. Additionally, malaria cases were intensified approximately 1 year after an El Niño event, a pattern that highlights the role of climate inter-annual variability in the epidemic patterns. Rainfall mediated the effect of ENSO on malaria locally. Particularly, rains from the last phase of the season had a critical role in the temporal dynamics of Plasmodium. The malaria-climate relationship was complex and transient, varying in strength with the region and species. By identifying temporal cycles of malaria we have made a first step in predicting high-risk years in Venezuela. Our findings emphasize the importance of analyzing high-resolution spatial-temporal data to better understand malaria transmission dynamics. Copyright © 2013 Elsevier B.V. All rights reserved.

Susceptibility to Plasmodium yoelii preerythrocytic infection in BALB/c substrains is determined at the point of hepatocyte invasion.

PubMed

Kaushansky, Alexis; Austin, Laura S; Mikolajczak, Sebastian A; Lo, Fang Y; Miller, Jessica L; Douglass, Alyse N; Arang, Nadia; Vaughan, Ashley M; Gardner, Malcolm J; Kappe, Stefan H I

2015-01-01

After transmission by Anopheles mosquitoes, Plasmodium sporozoites travel to the liver, infect hepatocytes, and rapidly develop as intrahepatocytic liver stages (LS). Rodent models of malaria exhibit large differences in the magnitude of liver infection, both between parasite species and between strains of mice. This has been mainly attributed to differences in innate immune responses and parasite infectivity. Here, we report that BALB/cByJ mice are more susceptible to Plasmodium yoelii preerythrocytic infection than BALB/cJ mice. This difference occurs at the level of early hepatocyte infection, but expression levels of reported host factors that are involved in infection do not correlate with susceptibility. Interestingly, BALB/cByJ hepatocytes are more frequently polyploid; thus, their susceptibility converges on the previously observed preference of sporozoites to infect polyploid hepatocytes. Gene expression analysis demonstrates hepatocyte-specific differences in mRNA abundance for numerous genes between BALB/cByJ and BALB/cJ mice, some of which encode hepatocyte surface molecules. These data suggest that a yet-unknown receptor for sporozoite infection, present at elevated levels on BALB/cByJ hepatocytes and also polyploid hepatocytes, might facilitate Plasmodium liver infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Establishing a China malaria diagnosis reference laboratory network for malaria elimination.

PubMed

Yin, Jian-hai; Yan, He; Huang, Fang; Li, Mei; Xiao, Hui-hui; Zhou, Shui-sen; Xia, Zhi-gui

2015-01-28

In China, the prevalence of malaria has reduced dramatically due to the elimination programme. The continued success of the programme will depend upon the accurate diagnosis of the disease in the laboratory. The basic requirements for this are a reliable malaria diagnosis laboratory network and quality management system to support case verification and source tracking. The baseline information of provincial malaria laboratories in the China malaria diagnosis reference laboratory network was collected and analysed, and a quality-assurance activity was carried out to assess their accuracies in malaria diagnosis by microscopy using WHO standards and PCR. By the end of 2013, nineteen of 24 provincial laboratories have been included in the network. In the study, a total of 168 staff were registered and there was no bias in their age, gender, education level, and position. Generally Plasmodium species were identified with great accuracy by microscopy and PCR. However, Plasmodium ovale was likely to be misdiagnosed as Plasmodium vivax by microscopy. China has established a laboratory network for primary malaria diagnosis which will cover a larger area. Currently, Plasmodium species can be identified fairly accurately by microscopy and PCR. However, laboratory staff need additional trainings on accurate identification of P. ovale microscopically and good performance of PCR operations.

Antibody-independent mechanisms regulate the establishment of chronic Plasmodium infection

PubMed Central

Lin, Jingwen; Cunningham, Deirdre; Tumwine, Irene; Kushinga, Garikai; McLaughlin, Sarah; Spence, Philip; Böhme, Ulrike; Sanders, Mandy; Conteh, Solomon; Bushell, Ellen; Metcalf, Tom; Billker, Oliver; Duffy, Patrick E.; Newbold, Chris; Berriman, Matthew; Langhorne, Jean

2017-01-01

Malaria is caused by parasites of the genus Plasmodium. All human-infecting Plasmodium species can establish long-lasting chronic infections1–5, creating an infectious reservoir to sustain transmission1,6. It is widely accepted that maintenance of chronic infection involves evasion of adaptive immunity by antigenic variation7. However, genes involved in this process have been identified in only two of five human-infecting species: P. falciparum and P. knowlesi. Furthermore, little is understood about the early events in establishment of chronic infection in these species. Using a rodent model we demonstrate that only a minority of parasites from among the infecting population, expressing one of several clusters of virulence-associated pir genes, establishes a chronic infection. This process occurs in different species of parasite and in different hosts. Establishment of chronicity is independent of adaptive immunity and therefore different from the mechanism proposed for maintainance of chronic P. falciparum infections7–9. Furthermore, we show that the proportions of parasites expressing different types of pir genes regulate the time taken to establish a chronic infection. Since pir genes are common to most, if not all, species of Plasmodium10, this process may be a common way of regulating the establishment of chronic infections. PMID:28165471

Effect of naturally occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

PubMed Central

Gomes, Fabio M.; Hixson, Bretta L.; Tyner, Miles D. W.; Ramirez, Jose Luis; Canepa, Gaspar E.; Alves e Silva, Thiago Luiz; Molina-Cruz, Alvaro; Keita, Moussa; Kane, Fouseyni; Traoré, Boïssé; Sogoba, Nafomon; Barillas-Mury, Carolina

2017-01-01

A naturally occurring Wolbachia strain (wAnga-Mali) was identified in mosquitoes of the Anopheles gambiae complex collected in the Malian villages of Dangassa and Kenieroba. Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from supergroup A and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of Plasmodium falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory Anopheles coluzzii (A. gambiae, M form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that wAnga-Mali infection does not limit early stages of Plasmodium infection in the mosquito, but it has a strong deleterious effect on sporozoites and reduces malaria transmission. PMID:29114059

A novel diagnostic method for malaria using loop-mediated isothermal amplification (LAMP) and MinION™ nanopore sequencer.

PubMed

Imai, Kazuo; Tarumoto, Norihito; Misawa, Kazuhisa; Runtuwene, Lucky Ronald; Sakai, Jun; Hayashida, Kyoko; Eshita, Yuki; Maeda, Ryuichiro; Tuda, Josef; Murakami, Takashi; Maesaki, Shigefumi; Suzuki, Yutaka; Yamagishi, Junya; Maeda, Takuya

2017-09-13

A simple and accurate molecular diagnostic method for malaria is urgently needed due to the limitations of conventional microscopic examination. In this study, we demonstrate a new diagnostic procedure for human malaria using loop mediated isothermal amplification (LAMP) and the MinION™ nanopore sequencer. We generated specific LAMP primers targeting the 18S-rRNA gene of all five human Plasmodium species including two P. ovale subspecies (P. falciparum, P. vivax, P. ovale wallikeri, P. ovale curtisi, P. knowlesi and P. malariae) and examined human blood samples collected from 63 malaria patients in Indonesia. Additionally, we performed amplicon sequencing of our LAMP products using MinION™ nanopore sequencer to identify each Plasmodium species. Our LAMP method allowed amplification of all targeted 18S-rRNA genes of the reference plasmids with detection limits of 10-100 copies per reaction. Among the 63 clinical samples, 54 and 55 samples were positive by nested PCR and our LAMP method, respectively. Identification of the Plasmodium species by LAMP amplicon sequencing analysis using the MinION™ was consistent with the reference plasmid sequences and the results of nested PCR. Our diagnostic method combined with LAMP and MinION™ could become a simple and accurate tool for the identification of human Plasmodium species, even in resource-limited situations.

Nested-PCR and a new ELISA-based NovaLisa test kit for malaria diagnosis in an endemic area of Thailand.

PubMed

Thongdee, Pimwan; Chaijaroenkul, Wanna; Kuesap, Jiraporn; Na-Bangchang, Kesara

2014-08-01

Microscopy is considered as the gold standard for malaria diagnosis although its wide application is limited by the requirement of highly experienced microscopists. PCR and serological tests provide efficient diagnostic performance and have been applied for malaria diagnosis and research. The aim of this study was to investigate the diagnostic performance of nested PCR and a recently developed an ELISA-based new rapid diagnosis test (RDT), NovaLisa test kit, for diagnosis of malaria infection, using microscopic method as the gold standard. The performance of nested-PCR as a malaria diagnostic tool is excellent with respect to its high accuracy, sensitivity, specificity, and ability to discriminate Plasmodium species. The sensitivity and specificity of nested-PCR compared with the microscopic method for detection of Plasmodium falciparum, Plasmodium vivax, and P. falciparum/P. vivax mixed infection were 71.4 vs 100%, 100 vs 98.7%, and 100 vs 95.0%, respectively. The sensitivity and specificity of the ELISA-based NovaLisa test kit compared with the microscopic method for detection of Plasmodium genus were 89.0 vs 91.6%, respectively. NovaLisa test kit provided comparable diagnostic performance. Its relatively low cost, simplicity, and rapidity enables large scale field application.

Malaria rapid diagnostic tests in elimination settings—can they find the last parasite?

PubMed Central

McMorrow, M. L.; Aidoo, M.; Kachur, S. P.

2016-01-01

Rapid diagnostic tests (RDTs) for malaria have improved the availability of parasite-based diagnosis throughout the malaria-endemic world. Accurate malaria diagnosis is essential for malaria case management, surveillance, and elimination. RDTs are inexpensive, simple to perform, and provide results in 15–20 min. Despite high sensitivity and specificity for Plasmodium falciparum infections, RDTs have several limitations that may reduce their utility in low-transmission settings: they do not reliably detect low-density parasitaemia (≤200 parasites/μL), many are less sensitive for Plasmodium vivax infections, and their ability to detect Plasmodium ovale and Plasmodium malariae is unknown. Therefore, in elimination settings, alternative tools with higher sensitivity for low-density infections (e.g. nucleic acid-based tests) are required to complement field diagnostics, and new highly sensitive and specific field-appropriate tests must be developed to ensure accurate diagnosis of symptomatic and asymptomatic carriers. As malaria transmission declines, the proportion of low-density infections among symptomatic and asymptomatic persons is likely to increase, which may limit the utility of RDTs. Monitoring malaria in elimination settings will probably depend on the use of more than one diagnostic tool in clinical-care and surveillance activities, and the combination of tools utilized will need to be informed by regular monitoring of test performance through effective quality assurance. PMID:21910780

A Key Role for Lipoic Acid Synthesis During Plasmodium Liver stage Development

PubMed Central

Falkard, Brie; Santha Kumar, T. R.; Hecht, Leonie-Sophie; Matthews, Krista A.; Henrich, Philipp P.; Gulati, Sonia; Lewis, Rebecca E.; Manary, Micah J.; Winzeler, Elizabeth A.; Sinnis, Photini; Prigge, Sean T.; Heussler, Volker; Deschermeier, Christina; Fidock, David

2013-01-01

SUMMARY The successful navigation of malaria parasites through their life cycle, which alternates between vertebrate hosts and mosquito vectors, requires a complex interplay of metabolite synthesis and salvage pathways. Using the rodent parasite Plasmodium berghei, we have explored the synthesis and scavenging pathways for lipoic acid, a short-chain fatty acid derivative that regulates the activity of α-ketoacid dehydrogenases including pyruvate dehydrogenase. In Plasmodium, lipoic acid is either synthesized de novo in the apicoplast or is scavenged from the host into the mitochondrion. Our data show that sporozoites lacking the apicoplast lipoic acid protein ligase LipB are markedly attenuated in their infectivity for mice, and in vitro studies document a very late liver stage arrest shortly before the final phase of intra-hepatic parasite maturation. LipB-deficient asexual blood stage parasites show unimpaired rates of growth in normal in vitro or in vivo conditions. However, these parasites showed reduced growth in lipid-restricted conditions induced by treatment with the lipoic acid analog 8-bromo-octanoate or with the lipid-reducing agent clofibrate. This finding has implications for understanding Plasmodium pathogenesis in malnourished children that bear the brunt of malarial disease. This study also highlights the potential of exploiting lipid metabolism pathways for the design of genetically attenuated sporozoite vaccines. PMID:23490300

Plasmodium vivax: modern strategies to study a persistent parasite's life cycle.

PubMed

Galinski, Mary R; Meyer, Esmeralda V S; Barnwell, John W

2013-01-01

Plasmodium vivax has unique attributes to support its survival in varying ecologies and climates. These include hypnozoite forms in the liver, an invasion preference for reticulocytes, caveola-vesicle complex structures in the infected erythrocyte membrane and rapidly forming and circulating gametocytes. These characteristics make this species very different from P. falciparum. Plasmodium cynomolgi and other related simian species have identical biology and can serve as informative models of P. vivax infections. Plasmodium vivax and its model parasites can be grown in non-human primates (NHP), and in short-term ex vivo cultures. For P. vivax, in the absence of in vitro culture systems, these models remain highly relevant side by side with human clinical studies. While post-genomic technologies allow for greater exploration of P. vivax-infected blood samples from humans, these come with restrictions. Two advantages of NHP models are that infections can be experimentally tailored to address hypotheses, including genetic manipulation. Also, systems biology approaches can capitalise on computational biology combined with set experimental infection periods and protocols, which may include multiple sampling times, different types of samples, and the broad use of "omics" technologies. Opportunities for research on vivax malaria are increasing with the use of existing and new methodological strategies in combination with modern technologies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vital and dispensable roles of Plasmodium multidrug resistance transporters during blood- and mosquito-stage development.

PubMed

Rijpma, Sanna R; van der Velden, Maarten; Annoura, Takeshi; Matz, Joachim M; Kenthirapalan, Sanketha; Kooij, Taco W A; Matuschewski, Kai; van Gemert, Geert-Jan; van de Vegte-Bolmer, Marga; Siebelink-Stoter, Rianne; Graumans, Wouter; Ramesar, Jai; Klop, Onny; Russel, Frans G M; Sauerwein, Robert W; Janse, Chris J; Franke-Fayard, Blandine M; Koenderink, Jan B

2016-07-01

Multidrug resistance (MDR) proteins belong to the B subfamily of the ATP Binding Cassette (ABC) transporters, which export a wide range of compounds including pharmaceuticals. In this study, we used reverse genetics to study the role of all seven Plasmodium MDR proteins during the life cycle of malaria parasites. Four P. berghei genes (encoding MDR1, 4, 6 and 7) were refractory to deletion, indicating a vital role during blood stage multiplication and validating them as potential targets for antimalarial drugs. Mutants lacking expression of MDR2, MDR3 and MDR5 were generated in both P. berghei and P. falciparum, indicating a dispensable role for blood stage development. Whereas P. berghei mutants lacking MDR3 and MDR5 had a reduced blood stage multiplication in vivo, blood stage growth of P. falciparum mutants in vitro was not significantly different. Oocyst maturation and sporozoite formation in Plasmodium mutants lacking MDR2 or MDR5 was reduced. Sporozoites of these P. berghei mutants were capable of infecting mice and life cycle completion, indicating the absence of vital roles during liver stage development. Our results demonstrate vital and dispensable roles of MDR proteins during blood stages and an important function in sporogony for MDR2 and MDR5 in both Plasmodium species. © 2016 John Wiley & Sons Ltd.

Multidrug ATP-binding cassette transporters are essential for hepatic development of Plasmodium sporozoites.

PubMed

Rijpma, Sanna R; van der Velden, Maarten; González-Pons, Maria; Annoura, Takeshi; van Schaijk, Ben C L; van Gemert, Geert-Jan; van den Heuvel, Jeroen J M W; Ramesar, Jai; Chevalley-Maurel, Severine; Ploemen, Ivo H; Khan, Shahid M; Franetich, Jean-Francois; Mazier, Dominique; de Wilt, Johannes H W; Serrano, Adelfa E; Russel, Frans G M; Janse, Chris J; Sauerwein, Robert W; Koenderink, Jan B; Franke-Fayard, Blandine M

2016-03-01

Multidrug resistance-associated proteins (MRPs) belong to the C-family of ATP-binding cassette (ABC) transport proteins and are known to transport a variety of physiologically important compounds and to be involved in the extrusion of pharmaceuticals. Rodent malaria parasites encode a single ABC transporter subfamily C protein, whereas human parasites encode two: MRP1 and MRP2. Although associated with drug resistance, their biological function and substrates remain unknown. To elucidate the role of MRP throughout the parasite life cycle, Plasmodium berghei and Plasmodium falciparum mutants lacking MRP expression were generated. P. berghei mutants lacking expression of the single MRP as well as P. falciparum mutants lacking MRP1, MRP2 or both proteins have similar blood stage growth kinetics and drug-sensitivity profiles as wild type parasites. We show that MRP1-deficient parasites readily invade primary human hepatocytes and develop into mature liver stages. In contrast, both P. falciparum MRP2-deficient parasites and P. berghei mutants lacking MRP protein expression abort in mid to late liver stage development, failing to produce mature liver stages. The combined P. berghei and P. falciparum data are the first demonstration of a critical role of an ABC transporter during Plasmodium liver stage development. © 2015 John Wiley & Sons Ltd.

DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

PubMed Central

Sander, Adam F.; Lavstsen, Thomas; Rask, Thomas S.; Lisby, Michael; Salanti, Ali; Fordyce, Sarah L.; Jespersen, Jakob S.; Carter, Richard; Deitsch, Kirk W.; Theander, Thor G.; Pedersen, Anders Gorm; Arnot, David E.

2014-01-01

Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens. PMID:24253306

Higher microsatellite diversity in Plasmodium vivax than in sympatric Plasmodium falciparum populations in Pursat, Western Cambodia.

PubMed

Orjuela-Sánchez, Pamela; Sá, Juliana M; Brandi, Michelle C C; Rodrigues, Priscila T; Bastos, Melissa S; Amaratunga, Chanaki; Duong, Socheat; Fairhurst, Rick M; Ferreira, Marcelo U

2013-07-01

Previous microsatellite analyses of sympatric populations of Plasmodium vivax and Plasmodium falciparum in Brazil revealed higher diversity in the former species. However, it remains unclear whether regional species-specific differences in prevalence and transmission levels might account for these findings. Here, we examine sympatric populations of P. vivax (n=87) and P. falciparum (n=164) parasites from Pursat province, Western Cambodia, where both species are similarly prevalent. Using 10 genome-wide microsatellites for P. falciparum and 13 for P. vivax, we found that the P. vivax population was more diverse than the sympatric P. falciparum population (average virtual heterozygosity [HE], 0.87 vs. 0.66, P=0.003), with more multiple-clone infections (89.6% vs. 47.6%) and larger mean number of alleles per marker (16.2 vs. 11.1, P=0.07). Both populations showed significant multi-locus linkage disequilibrium suggestive of a predominantly clonal mode of parasite reproduction. The higher microsatellite diversity found in P. vivax isolates, compared to sympatric P. falciparum isolates, does not necessarily result from local differences in transmission level and may reflect differences in population history between species or increased mutation rates in P. vivax. Copyright © 2013 Elsevier Inc. All rights reserved.

Overview of the improvement of the ring-stage survival assay-a novel phenotypic assay for the detection of artemisinin-resistant Plasmodium falciparum.

PubMed

Zhang, Jie; Feng, Guo-Hua; Zou, Chun-Yan; Su, Pin-Can; Liu, Huai-E; Yang, Zhao-Qing

2017-11-18

Artemisinin resistance in Plasmodium falciparum threatens the remarkable efficacy of artemisinin-based combination therapies worldwide. Thus, greater insight into the resistance mechanism using monitoring tools is essential. The ring-stage survival assay is used for phenotyping artemisinin-resistance or decreased artemisinin sensitivity. Here, we review the progress of this measurement assay and explore its limitations and potential applications.

Expression, Extracellular Secretion, and Immunogenicity of the Plasmodium falciparum Sporozoite Surface Protein 2 in Salmonella Vaccine Strains

PubMed Central

Gómez-Duarte, Oscar G.; Pasetti, Marcela F.; Santiago, Araceli; Sztein, Marcelo B.; Hoffman, Stephen L.; Levine, Myron M.

2001-01-01

Deleting transmembrane α-helix motifs from Plasmodium falciparum sporozoite surface protein (SSP-2) allowed its secretion from Salmonella enterica serovar Typhimurium SL3261 and S. enterica serovar Typhi CVD 908-htrA by the Hly type I secretion system. In mice immunized intranasally, serovar Typhimurium constructs secreting SSP-2 stimulated greater gamma interferon splenocyte responses than did nonsecreting constructs (P = 0.04). PMID:11160021

Protection of Mice against Plasmodium yoelii Sporozoite Challenge with P. yoelii Merozoite Surface Protein 1 DNA Vaccines

PubMed Central

Becker, Sylvia I.; Wang, Ruobing; Hedstrom, Richard C.; Aguiar, Joao C.; Jones, Trevor R.; Hoffman, Stephen L.; Gardner, Malcolm J.

1998-01-01

Immunization of mice with DNA vaccines encoding the full-length form and C and N termini of Plasmodium yoelii merozoite surface protein 1 provided partial protection against sporozoite challenge and resulted in boosting of antibody titers after challenge. In C57BL/6 mice, two DNA vaccines provided protection comparable to that of recombinant protein consisting of the C terminus in Freund’s adjuvant. PMID:9632624

Novel 2-Phenoxyanilide Congeners Derived from a Hit Structure of the TCAMS: Synthesis and Evaluation of Their in Vitro Activity against Plasmodium falciparum.

PubMed

Weidner, Thomas; Nasereddin, Abed; Preu, Lutz; Grünefeld, Johann; Dzikowski, Ron; Kunick, Conrad

2016-02-17

The Tres Cantos Antimalarial Compound Set (TCAMS) is a publicly available compound library which contains 13533 hit structures with confirmed activity against Plasmodium falciparum, the infective agent responsible for malaria tropica. The TCAMS provides a variety of starting points for the investigation of new antiplasmodial drug leads. One of the promising compounds is TCMDC-137332, which seemed to be a good starting point due to its antiplasmodial potency and its predicted physicochemical properties. Several new analogues based on a 2-phenoxyanilide scaffold were synthesized by standard amide coupling reactions and were fully characterized regarding their identity and purity by spectroscopic and chromatographic methods. Furthermore, the results of the biological evaluation of all congeners against Plasmodium falciparum NF54 strains are presented. The findings of our in vitro screening could not confirm the presumed nanomolar antiplasmodial activity of TCMDC-137332 and its derivatives.

Characterizing the genetic diversity of the monkey malaria parasite Plasmodium cynomolgi

PubMed Central

Sutton, Patrick L.; Luo, Zunping; Divis, Paul C. S.; Friedrich, Volney K.; Conway, David J.; Singh, Balbir; Barnwell, John W.; Carlton, Jane M.; Sullivan, Steven A.

2016-01-01

Plasmodium cynomolgi is a malaria parasite that typically infects Asian macaque monkeys, and humans on rare occasions. P. cynomolgi serves as a model system for the human malaria parasite Plasmodium vivax, with which it shares such important biological characteristics as formation of a dormant liver stage and a preference to invade reticulocytes. While genomes of three P. cynomolgi strains have been sequenced, genetic diversity of P. cynomolgi has not been widely investigated. To address this we developed the first panel of P. cynomolgi microsatellite markers to genotype eleven P. cynomolgi laboratory strains and 18 field isolates from Sarawak, Malaysian Borneo. We found diverse genotypes among most of the laboratory strains, though two nominally different strains were found to be genetically identical, We also investigated sequence polymorphism in two erythrocyte invasion gene families, the reticulocyte binding protein and Duffy binding protein genes, in these strains. We also observed copy number variation in rbp genes. PMID:26980604

Validation of the proteasome as a therapeutic target in Plasmodium using an epoxyketone inhibitor with parasite-specific toxicity

PubMed Central

Li, Hao; Ponder, Elizabeth L.; Verdoes, Martijn; Asbjornsdottir, Kristijana H.; Deu, Edgar; Edgington, Laura E.; Lee, Jeong Tae; Kirk, Christopher J.; Demo, Susan D.; Williamson, Kim C.; Bogyo, Matthew

2012-01-01

Summary The Plasmodium proteasome has been suggested to be a potential anti-malarial drug target, however toxicity of inhibitors has prevented validation of this enzyme in vivo. We report here a screen of a library of 670 analogs of the recently FDA approved inhibitor, carfilzomib, to identify compounds that selectively kill parasites. We identified one compound, PR3, that has significant parasite killing activity in vitro but dramatically reduced toxicity in host cells. We found that this parasite-specific toxicity is not due to selective targeting of the Plasmodium proteasome over the host proteasome, but instead is due to a lack of activity against one of the human proteasome subunits. Subsequently, we used PR3 to significantly reduce parasite load in P. berghei infected mice without host toxicity, thus validating the proteasome as a viable anti-malarial drug target. PMID:23142757

Mosquito Vectors and the Globalization of Plasmodium falciparum Malaria.

PubMed

Molina-Cruz, Alvaro; Zilversmit, Martine M; Neafsey, Daniel E; Hartl, Daniel L; Barillas-Mury, Carolina

2016-11-23

Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P. falciparum Pfs47 gene allows the parasite to evade mosquito immune detection. Here, we review the origin and globalization of P. falciparum and integrate this history with analysis of the biology, evolution, and dispersal of the main mosquito vectors. This new perspective broadens our understanding of P. falciparum population structure and the dispersal of important parasite genetic traits.

A case of severe Plasmodium knowlesi in a splenectomized patient.

PubMed

Boo, Yang Liang; Lim, Hong Tak; Chin, Pek Woon; Lim, Suat Yee; Hoo, Fan Kee

2016-02-01

Plasmodium knowlesi, a zoonotic malaria, is now considered the fifth species of Plasmodium causing malaria in humans. With its 24-hour erythrocytic stage of development, it has raised concern regarding its high potential in replicating and leading to severe illness. Spleen is an important site for removal of parasitized red blood cells and generating immunity. We reported a case of knowlesi malaria in a non-immune, splenectomized patient. We observed the delay in parasite clearance, high parasitic counts, and severe illness at presentation. A thorough search through literature revealed several case reports on falciparum and vivax malaria in splenectomized patients. However, literature available for knowlesi malaria in splenectomized patient is limited. Further studies need to be carried out to clarify the role of spleen in host defense against human malaria especially P. knowlesi. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Predictions of avian Plasmodium expansion under climate change.

PubMed

Loiseau, Claire; Harrigan, Ryan J; Bichet, Coraline; Julliard, Romain; Garnier, Stéphane; Lendvai, Adám Z; Chastel, Olivier; Sorci, Gabriele

2013-01-01

Vector-borne diseases are particularly responsive to changing environmental conditions. Diurnal temperature variation has been identified as a particularly important factor for the development of malaria parasites within vectors. Here, we conducted a survey across France, screening populations of the house sparrow (Passer domesticus) for malaria (Plasmodium relictum). We investigated whether variation in remotely-sensed environmental variables accounted for the spatial variation observed in prevalence and parasitemia. While prevalence was highly correlated to diurnal temperature range and other measures of temperature variation, environmental conditions could not predict spatial variation in parasitemia. Based on our empirical data, we mapped malaria distribution under climate change scenarios and predicted that Plasmodium occurrence will spread to regions in northern France, and that prevalence levels are likely to increase in locations where transmission already occurs. Our findings, based on remote sensing tools coupled with empirical data suggest that climatic change will significantly alter transmission of malaria parasites.

Plasmodium knowlesi malaria in a traveller returning from the Philippines to Italy, 2016.

PubMed

De Canale, Ettore; Sgarabotto, Dino; Marini, Giulia; Menegotto, Nicola; Masiero, Serena; Akkouche, Wassim; Biasolo, Maria Angela; Barzon, Luisa; Palù, Giorgio

2017-10-01

Plasmodium knowlesi is a simian parasite responsible for most human cases of malaria in Malaysian Borneo. A timely recognition of infection is crucial because of the risk of severe disease due to the rapid increase in parasitemia. We report a case of P. knowlesi infection in a traveller who developed fever and thrombocytopenia after returning from the Philippines in 2016. Rapid antigen test was negative, microscopy examination showed parasites similar to Plasmodium malariae, with a parasite count of 10,000 parasites per μL blood, while molecular testing identified P. knowlesi infection. Treatment with atovaquone-proguanil led to resolution of fever and restoration of platelet count in two days. P. knowlesi infection should be suspected in febrile travellers returning from South East Asia. Due to the low sensitivity of rapid antigen tests and the low specificity of microscopy, confirmation by molecular tests is recommended.

Co-incidental Plasmodium Knowlesi and Mucormycosis infections presenting with acute kidney injury and lower gastrointestinal bleeding.

PubMed

Ramaswami, Arunachalam; Pisharam, Jayakrishnan K; Aung, Hla; Ghazala, Kafeel; Maboud, Khalil; Chong, Vui Heng; Tan, Jackson

2013-01-01

Plasmodium knowlesi is frequently reported in Southeast Asian countries and is now widely regarded as the fifth malarial parasite. Mucormycosis is a rare fungal infection that can occur in patients with a weakened immune system. We report a case of acute kidney injury secondary to Plasmodium knowlesi malaria infection and mucormycosis fungal infection. In addition, the patient also had lower gastrointestinal bleeding from invasive gastrointestinal mucormycosis. P. knowlesi infection was diagnosed by blood film and mucormycosis was diagnosed by histopathological examination of biopsy specimen of the colon. The patient recovered with antimalarial treatment (Quinine), antifungal treatment (Lipophilic Amphotericin), and supportive hemodialysis treatment. We hypothesize that P. knowlesi malarial infection can lower the immunologic threshold and predisposes vulnerable individuals to rare disseminated fungal infections. To the best of our knowledge, this is the first P. Knowlesi malaria-associated invasive fungal infection reported in the literature.

Population genomics studies identify signatures of global dispersal and drug resistance in Plasmodium vivax

PubMed Central

Hupalo, Daniel N; Luo, Zunping; Melnikov, Alexandre; Sutton, Patrick L; Rogov, Peter; Escalante, Ananias; Vallejo, Andrés F; Herrera, Sócrates; Arévalo-Herrera, Myriam; Fan, Qi; Wang, Ying; Cui, Liwang; Lucas, Carmen M; Durand, Salomon; Sanchez, Juan F; Baldeviano, G Christian; Lescano, Andres G; Laman, Moses; Barnadas, Celine; Barry, Alyssa; Mueller, Ivo; Kazura, James W; Eapen, Alex; Kanagaraj, Deena; Valecha, Neena; Ferreira, Marcelo U; Roobsoong, Wanlapa; Nguitragool, Wang; Sattabonkot, Jetsumon; Gamboa, Dionicia; Kosek, Margaret; Vinetz, Joseph M; González-Cerón, Lilia; Birren, Bruce W; Neafsey, Daniel E; Carlton, Jane M

2017-01-01

Plasmodium vivax is a major public health burden, responsible for the majority of malaria infections outside Africa. We explored the impact of demographic history and selective pressures on the P. vivax genome by sequencing 182 clinical isolates sampled from 11 countries across the globe, using hybrid selection to overcome human DNA contamination. We confirmed previous reports of high genomic diversity in P. vivax relative to the more virulent Plasmodium falciparum species; regional populations of P. vivax exhibited greater diversity than the global P. falciparum population, indicating a large and/or stable population. Signals of natural selection suggest that P. vivax is evolving in response to antimalarial drugs and is adapting to regional differences in the human host and the mosquito vector. These findings underline the variable epidemiology of this parasite species and highlight the breadth of approaches that may be required to eliminate P. vivax globally. PMID:27348298

Antimalarial activity of three Pakistani medicinal plants.

PubMed

Irshad, Saba; Mannan, Abdul; Mirza, Bushra

2011-10-01

This study was conducted to determine the in vitro anti-malarial activity of three medicinal plants, Picrorhiza kurroa, Caesalpinia bonducella and Artemisia absinthium of Pakistan. Different extracts of various parts of these plants were prepared by maceration and percolation, and were evaluated for their antimalarial activity. Aqueous, cold alcoholic and hot alcoholic extracts of Picrorhiza kurroa showed 34%, 100% and 90% inhibition in growth of Plasmodium falciparum, respectively, at 2.00 mg/ml. While aqueous, cold alcoholic and hot alcoholic extracts of Caesalpinia bonducella showed 65%, 56% and 76% inhibition in growth of Plasmodium falciparum, respectively at same concentrations. In the case of Artemisia absinthium, aqueous, cold alcoholic and hot alcoholic extract of Artemisia absinthium showed 35%, 55% and 21% inhibition in growth of Plasmodium falciparum, respectively at 2.00 mg/ml. In our study, extracts of Picrorhiza kurroa were found good for traditional therapy with highly significant results.

Challenges of assessing the clinical efficacy of asexual blood-stage Plasmodium falciparum malaria vaccines.

PubMed

Sheehy, Susanne H; Douglas, Alexander D; Draper, Simon J

2013-09-01

In the absence of any highly effective vaccine candidate against Plasmodium falciparum malaria, it remains imperative for the field to pursue all avenues that may lead to the successful development of such a formulation. The development of a subunit vaccine targeting the asexual blood-stage of Plasmodium falciparum malaria infection has proven particularly challenging with only limited success to date in clinical trials. However, only a fraction of potential blood-stage vaccine antigens have been evaluated as targets, and a number of new promising candidate antigen formulations and delivery platforms are approaching clinical development. It is therefore essential that reliable and sensitive methods of detecting, or ruling out, even modest efficacy of blood-stage vaccines in small clinical trials be established. In this article we evaluate the challenges facing blood-stage vaccine developers, assess the appropriateness and limitations of various in vivo approaches for efficacy assessment and suggest future directions for the field.

Small-molecule xenomycins inhibit all stages of the Plasmodium life cycle.

PubMed

Erath, Jessey; Gallego-Delgado, Julio; Xu, Wenyue; Andriani, Grasiella; Tanghe, Scott; Gurova, Katerina V; Gudkov, Andrei; Purmal, Andrei; Rydkina, Elena; Rodriguez, Ana

2015-03-01

Widespread resistance to most antimalaria drugs in use has prompted the search for novel candidate compounds with activity against Plasmodium asexual blood stages to be developed for treatment. In addition, the current malaria eradication programs require the development of drugs that are effective against all stages of the parasite life cycle. We have analyzed the antimalarial properties of xenomycins, a novel subclass of small molecule compounds initially isolated for anticancer activity and similarity to quinacrine in biological effects on mammalian cells. In vitro studies show potent activity of Xenomycins against Plasmodium falciparum. Oral administration of xenomycins in mouse models result in effective clearance of liver and blood asexual and sexual stages, as well as effective inhibition of transmission to mosquitoes. These characteristics position xenomycins as antimalarial candidates with potential activity in prevention, treatment and elimination of this disease. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Imaging Plasmodium Immunobiology in Liver, Brain, and Lung

PubMed Central

Frevert, Ute; Nacer, Adéla; Cabrera, Mynthia; Movila, Alexandru; Leberl, Maike

2013-01-01

Plasmodium falciparum malaria is responsible for the deaths of over half a million African children annually. Until a decade ago, dynamic analysis of the malaria parasite was limited to in vitro systems with the typical limitations associated with 2D monocultures or entirely artificial surfaces. Due to extremely low parasite densities, the liver was considered a black box in terms of Plasmodium sporozoite invasion, liver stage development, and merozoite release into the blood. Further, nothing was known about the behavior of blood stage parasites in organs such as brain where clinical signs manifest and the ensuing immune response of the host that may ultimately result in a fatal outcome. The advent of fluorescent parasites, advances in imaging technology, and availability of an ever-increasing number of cellular and molecular probes have helped illuminate many steps along the pathogenetic cascade of this deadly tropical parasite. PMID:24076429

Flow cytometry as a tool for analyzing changes in Plasmodium falciparum cell cycle following treatment with indol compounds.

PubMed

Schuck, Desirée Cigaran; Ribeiro, Ramira Yuri; Nery, Arthur A; Ulrich, Henning; Garcia, Célia R S

2011-11-01

Melatonin and its derivatives modulate the Plasmodium falciparum and Plasmodium chabaudi cell cycle. Flow cytometry was employed together with the nucleic acid dye YOYO-1 allowing precise discrimination between mono- and multinucleated forms of P. falciparum-infected red blood cell. The use of YOYO-1 permitted excellent discrimination between uninfected and infected red blood cells as well as between early and late parasite stages. Fluorescence intensities of schizont-stage parasites were about 10-fold greater than those of ring-trophozoite form parasites. Melatonin and related indolic compounds including serotonin, N-acetyl-serotonin and tryptamine induced an increase in the percentage of multinucleated forms compared to non-treated control cultures. YOYO-1 staining of infected erythrocyte and subsequent flow cytometry analysis provides a powerful tool in malaria research for screening of bioactive compounds. Copyright © 2011 International Society for Advancement of Cytometry.

Rodent Plasmodium-infected red blood cells: imaging their fates and interactions within their hosts.

PubMed

Claser, Carla; Malleret, Benoit; Peng, Kaitian; Bakocevic, Nadja; Gun, Sin Yee; Russell, Bruce; Ng, Lai Guan; Rénia, Laurent

2014-02-01

Malaria, a disease caused by the Plasmodium parasite, remains one of the most deadly infectious diseases known to mankind. The parasite has a complex life cycle, of which only the erythrocytic stage is responsible for the diverse pathologies induced during infection. To date, the disease mechanisms that underlie these pathologies are still poorly understood. In the case of infections caused by Plasmodium falciparum, the species responsible for most malaria related deaths, pathogenesis is thought to be due to the sequestration of infected red blood cells (IRBCs) in deep tissues. Other human and rodent malaria parasite species are also known to exhibit sequestration. Here, we review the different techniques that allow researchers to study how rodent malaria parasites modify their host cells, the distribution of IRBCs in vivo as well as the interactions between IRBCs and host tissues. © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

[Association of methemoglobinemia and glucose-6-phosphate dehydrogenase deficiency in malaria patients treated with primaquine].

PubMed

Santana, Marli Stela; da Rocha, Marcos Antonio Ferreira; Arcanjo, Ana Ruth Lima; Sardinha, José Felipe Jardim; Alecrim, Wilson Duarte; Alecrim, Maria das Graças Costa

2007-01-01

This study had the aim of investigating occurrences of methemoglobinemia among individuals with glucose-6-phosphate dehydrogenase deficiency during treatment for malaria infection using primaquine. Patients with a diagnosis of malaria caused by Plasmodium vivax or the V+F mixture (Plasmodium vivax + Plasmodium falciparum) were selected. Group 1 consisted of 74 individuals with a clinical diagnosis of methemoglobinemia and Group 2 consisted of 161 individuals without a clinical diagnosis of methemoglobinemia. The glucose-6-phosphate dehydrogenase deficiency rates (numbers of enzymopenic individuals) in Groups 1 and 2 were 51.3% (38) and 8.7% (14) respectively. These data demonstrated a statistically significant association with methemoglobinemia only among the individuals in Group 1 (p<0.05). Investigation of the relationship between methemoglobinemia and glucose-6-phosphate dehydrogenase deficiency showed that there was a possible association such that enzymopenic individuals may develop methemoglobinemia more frequently.

Acyclic Immucillin Phosphonates. Second-Generation Inhibitors of Plasmodium falciparum Hypoxanthine- Guanine-Xanthine Phosphoribosyltransferase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hazelton, Keith Z.; Ho, Meng-Chaio; Cassera, Maria B.

We found that Plasmodium falciparum is the primary cause of deaths from malaria. It is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5'-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. We present a class of HGXPRT inhibitors, the acyclic immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPsmore » are simple, potent, selective, and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria.« less

A zoonotic human infection with simian malaria, Plasmodium knowlesi, in Central Kalimantan, Indonesia.

PubMed

Setiadi, Wuryantari; Sudoyo, Herawati; Trimarsanto, Hidayat; Sihite, Boy Adventus; Saragih, Riahdo Juliarman; Juliawaty, Rita; Wangsamuda, Suradi; Asih, Puji Budi Setia; Syafruddin, Din

2016-04-16

The Indonesian archipelago is endemic for malaria. Although Plasmodium falciparum and P. vivax are the most common causes for malaria cases, P. malariae and P. ovale are also present in certain regions. Zoonotic case of malaria had just became the attention of public health communities after the Serawak study in 2004. However, zoonotic case in Indonesia is still under reported; only one published report of knowlesi malaria in South Kalimantan in 2010. A case of Plasmodium knowlesi infection in a worker from a charcoal mining company in Central Kalimantan, Indonesia was described. The worker suffered from fever following his visit to a lowland forest being cut and converted into a new mining location. This study confirmed a zoonotic infection using polymerase chain reaction amplification and Sanger sequencing of plasmodial DNA encoding the mitochondrial cytochrome c oxidase subunit I (mtCOI).

Population genomics studies identify signatures of global dispersal and drug resistance in Plasmodium vivax.

PubMed

Hupalo, Daniel N; Luo, Zunping; Melnikov, Alexandre; Sutton, Patrick L; Rogov, Peter; Escalante, Ananias; Vallejo, Andrés F; Herrera, Sócrates; Arévalo-Herrera, Myriam; Fan, Qi; Wang, Ying; Cui, Liwang; Lucas, Carmen M; Durand, Salomon; Sanchez, Juan F; Baldeviano, G Christian; Lescano, Andres G; Laman, Moses; Barnadas, Celine; Barry, Alyssa; Mueller, Ivo; Kazura, James W; Eapen, Alex; Kanagaraj, Deena; Valecha, Neena; Ferreira, Marcelo U; Roobsoong, Wanlapa; Nguitragool, Wang; Sattabonkot, Jetsumon; Gamboa, Dionicia; Kosek, Margaret; Vinetz, Joseph M; González-Cerón, Lilia; Birren, Bruce W; Neafsey, Daniel E; Carlton, Jane M

2016-08-01

Plasmodium vivax is a major public health burden, responsible for the majority of malaria infections outside Africa. We explored the impact of demographic history and selective pressures on the P. vivax genome by sequencing 182 clinical isolates sampled from 11 countries across the globe, using hybrid selection to overcome human DNA contamination. We confirmed previous reports of high genomic diversity in P. vivax relative to the more virulent Plasmodium falciparum species; regional populations of P. vivax exhibited greater diversity than the global P. falciparum population, indicating a large and/or stable population. Signals of natural selection suggest that P. vivax is evolving in response to antimalarial drugs and is adapting to regional differences in the human host and the mosquito vector. These findings underline the variable epidemiology of this parasite species and highlight the breadth of approaches that may be required to eliminate P. vivax globally.

Infection of Laboratory-Colonized Anopheles darlingi Mosquitoes by Plasmodium vivax

PubMed Central

Moreno, Marta; Tong, Carlos; Guzmán, Mitchel; Chuquiyauri, Raul; Llanos-Cuentas, Alejandro; Rodriguez, Hugo; Gamboa, Dionicia; Meister, Stephan; Winzeler, Elizabeth A.; Maguina, Paula; Conn, Jan E.; Vinetz, Joseph M.

2014-01-01

Anopheles darlingi Root is the most important malaria vector in the Amazonia region of South America. However, continuous propagation of An. darlingi in the laboratory has been elusive, limiting entomological, genetic/genomic, and vector–pathogen interaction studies of this mosquito species. Here, we report the establishment of an An. darlingi colony derived from wild-caught mosquitoes obtained in the northeastern Peruvian Amazon region of Iquitos in the Loreto Department. We show that the numbers of eggs, larvae, pupae, and adults continue to rise at least to the F6 generation. Comparison of feeding Plasmodium vivax ex vivo of F4 and F5 to F1 generation mosquitoes showed the comparable presence of oocysts and sporozoites, with numbers that corresponded to blood-stage asexual parasitemia and gametocytemia, confirming P. vivax vectorial capacity in the colonized mosquitoes. These results provide new avenues for research on An. darlingi biology and study of An. darlingi–Plasmodium interactions. PMID:24534811

Infection of laboratory-colonized Anopheles darlingi mosquitoes by Plasmodium vivax.

PubMed

Moreno, Marta; Tong, Carlos; Guzmán, Mitchel; Chuquiyauri, Raul; Llanos-Cuentas, Alejandro; Rodriguez, Hugo; Gamboa, Dionicia; Meister, Stephan; Winzeler, Elizabeth A; Maguina, Paula; Conn, Jan E; Vinetz, Joseph M

2014-04-01

Anopheles darlingi Root is the most important malaria vector in the Amazonia region of South America. However, continuous propagation of An. darlingi in the laboratory has been elusive, limiting entomological, genetic/genomic, and vector-pathogen interaction studies of this mosquito species. Here, we report the establishment of an An. darlingi colony derived from wild-caught mosquitoes obtained in the northeastern Peruvian Amazon region of Iquitos in the Loreto Department. We show that the numbers of eggs, larvae, pupae, and adults continue to rise at least to the F6 generation. Comparison of feeding Plasmodium vivax ex vivo of F4 and F5 to F1 generation mosquitoes showed the comparable presence of oocysts and sporozoites, with numbers that corresponded to blood-stage asexual parasitemia and gametocytemia, confirming P. vivax vectorial capacity in the colonized mosquitoes. These results provide new avenues for research on An. darlingi biology and study of An. darlingi-Plasmodium interactions.

Identification of GAPDH on the surface of Plasmodium sporozoites as a new candidate for targeting malaria liver invasion

PubMed Central

Kim, Min-Sik

2016-01-01

Malaria transmission begins when an infected mosquito delivers Plasmodium sporozoites into the skin. The sporozoite subsequently enters the circulation and infects the liver by preferentially traversing Kupffer cells, a macrophage-like component of the liver sinusoidal lining. By screening a phage display library, we previously identified a peptide designated P39 that binds to CD68 on the surface of Kupffer cells and blocks sporozoite traversal. In this study, we show that the P39 peptide is a structural mimic of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) on the sporozoite surface and that GAPDH directly interacts with CD68 on the Kupffer cell surface. Importantly, an anti-P39 antibody significantly inhibits sporozoite liver invasion without cross-reacting with mammalian GAPDH. Therefore, Plasmodium-specific GAPDH epitopes may provide novel antigens for the development of a prehepatic vaccine. PMID:27551151

Identification of GAPDH on the surface of Plasmodium sporozoites as a new candidate for targeting malaria liver invasion.

PubMed

Cha, Sung-Jae; Kim, Min-Sik; Pandey, Akhilesh; Jacobs-Lorena, Marcelo

2016-09-19

Malaria transmission begins when an infected mosquito delivers Plasmodium sporozoites into the skin. The sporozoite subsequently enters the circulation and infects the liver by preferentially traversing Kupffer cells, a macrophage-like component of the liver sinusoidal lining. By screening a phage display library, we previously identified a peptide designated P39 that binds to CD68 on the surface of Kupffer cells and blocks sporozoite traversal. In this study, we show that the P39 peptide is a structural mimic of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) on the sporozoite surface and that GAPDH directly interacts with CD68 on the Kupffer cell surface. Importantly, an anti-P39 antibody significantly inhibits sporozoite liver invasion without cross-reacting with mammalian GAPDH. Therefore, Plasmodium-specific GAPDH epitopes may provide novel antigens for the development of a prehepatic vaccine. © 2016 Cha et al.

Plasmodium falciparum in the southeastern Atlantic forest: a challenge to the bromeliad-malaria paradigm?

PubMed

Laporta, Gabriel Zorello; Burattini, Marcelo Nascimento; Levy, Debora; Fukuya, Linah Akemi; de Oliveira, Tatiane Marques Porangaba; Maselli, Luciana Morganti Ferreira; Conn, Jan Evelyn; Massad, Eduardo; Bydlowski, Sergio Paulo; Sallum, Maria Anice Mureb

2015-04-25

Recently an unexpectedly high prevalence of Plasmodium falciparum was found in asymptomatic blood donors living in the southeastern Brazilian Atlantic forest. The bromeliad-malaria paradigm assumes that transmission of Plasmodium vivax and Plasmodium malariae involves species of the subgenus Kerteszia of Anopheles and only a few cases of P. vivax malaria are reported annually in this region. The expectations of this paradigm are a low prevalence of P. vivax and a null prevalence of P. falciparum. Therefore, the aim of this study was to verify if P. falciparum is actively circulating in the southeastern Brazilian Atlantic forest remains. In this study, anophelines were collected with Shannon and CDC-light traps in seven distinct Atlantic forest landscapes over a 4-month period. Field-collected Anopheles mosquitoes were tested by real-time PCR assay in pools of ten, and then each mosquito from every positive pool, separately for P. falciparum and P. vivax. Genomic DNA of P. falciparum or P. vivax from positive anophelines was then amplified by traditional PCR for sequencing of the 18S ribosomal DNA to confirm Plasmodium species. Binomial probabilities were calculated to identify non-random results of the P. falciparum-infected anopheline findings. The overall proportion of anophelines naturally infected with P. falciparum was 4.4% (21/480) and only 0.8% (4/480) with P. vivax. All of the infected mosquitoes were found in intermixed natural and human-modified environments and most were Anopheles cruzii (22/25 = 88%, 18 P. falciparum plus 4 P. vivax). Plasmodium falciparum was confirmed by sequencing in 76% (16/21) of positive mosquitoes, whereas P. vivax was confirmed in only 25% (1/4). Binomial probabilities suggest that P. falciparum actively circulates throughout the region and that there may be a threshold of the forested over human-modified environment ratio upon which the proportion of P. falciparum-infected anophelines increases significantly. These results show that P. falciparum actively circulates, in higher proportion than P. vivax, among Anopheles mosquitoes of fragments of the southeastern Brazilian Atlantic forest. This finding challenges the classical bromeliad-malaria paradigm, which considers P. vivax circulation as the driver for the dynamics of residual malaria transmission in this region.

Development of the piggyBac transposable system for Plasmodium berghei and its application for random mutagenesis in malaria parasites

PubMed Central

2011-01-01

Background The genome of a number of species of malaria parasites (Plasmodium spp.) has been sequenced in the hope of identifying new drug and vaccine targets. However, almost one-half of predicted Plasmodium genes are annotated as hypothetical and are difficult to analyse in bulk due to the inefficiency of current reverse genetic methodologies for Plasmodium. Recently, it has been shown that the transposase piggyBac integrates at random into the genome of the human malaria parasite P. falciparum offering the possibility to develop forward genetic screens to analyse Plasmodium gene function. This study reports the development and application of the piggyBac transposition system for the rodent malaria parasite P. berghei and the evaluation of its potential as a tool in forward genetic studies. P. berghei is the most frequently used malaria parasite model in gene function analysis since phenotype screens throughout the complete Plasmodium life cycle are possible both in vitro and in vivo. Results We demonstrate that piggyBac based gene inactivation and promoter-trapping is both easier and more efficient in P. berghei than in the human malaria parasite, P. falciparum. Random piggyBac-mediated insertion into genes was achieved after parasites were transfected with the piggyBac donor plasmid either when transposase was expressed either from a helper plasmid or a stably integrated gene in the genome. Characterization of more than 120 insertion sites demonstrated that more than 70 most likely affect gene expression classifying their protein products as non-essential for asexual blood stage development. The non-essential nature of two of these genes was confirmed by targeted gene deletion one of which encodes P41, an ortholog of a human malaria vaccine candidate. Importantly for future development of whole genome phenotypic screens the remobilization of the piggyBac element in parasites that stably express transposase was demonstrated. Conclusion These data demonstrate that piggyBac behaved as an efficient and random transposon in P. berghei. Remobilization of piggyBac element shows that with further development the piggyBac system can be an effective tool to generate random genome-wide mutation parasite libraries, for use in large-scale phenotype screens in vitro and in vivo. PMID:21418605

Multiplicity and molecular epidemiology of Plasmodium vivax and Plasmodium falciparum infections in East Africa.

PubMed

Zhong, Daibin; Lo, Eugenia; Wang, Xiaoming; Yewhalaw, Delenasaw; Zhou, Guofa; Atieli, Harrysone E; Githeko, Andrew; Hemming-Schroeder, Elizabeth; Lee, Ming-Chieh; Afrane, Yaw; Yan, Guiyun

2018-05-02

Parasite genetic diversity and multiplicity of infection (MOI) affect clinical outcomes, response to drug treatment and naturally-acquired or vaccine-induced immunity. Traditional methods often underestimate the frequency and diversity of multiclonal infections due to technical sensitivity and specificity. Next-generation sequencing techniques provide a novel opportunity to study complexity of parasite populations and molecular epidemiology. Symptomatic and asymptomatic Plasmodium vivax samples were collected from health centres/hospitals and schools, respectively, from 2011 to 2015 in Ethiopia. Similarly, both symptomatic and asymptomatic Plasmodium falciparum samples were collected, respectively, from hospitals and schools in 2005 and 2015 in Kenya. Finger-pricked blood samples were collected and dried on filter paper. Long amplicon (> 400 bp) deep sequencing of merozoite surface protein 1 (msp1) gene was conducted to determine multiplicity and molecular epidemiology of P. vivax and P. falciparum infections. The results were compared with those based on short amplicon (117 bp) deep sequencing. A total of 139 P. vivax and 222 P. falciparum samples were pyro-sequenced for pvmsp1 and pfmsp1, yielding a total of 21 P. vivax and 99 P. falciparum predominant haplotypes. The average MOI for P. vivax and P. falciparum were 2.16 and 2.68, respectively, which were significantly higher than that of microsatellite markers and short amplicon (117 bp) deep sequencing. Multiclonal infections were detected in 62.2% of the samples for P. vivax and 74.8% of the samples for P. falciparum. Four out of the five subjects with recurrent P. vivax malaria were found to be a relapse 44-65 days after clearance of parasites. No difference was observed in MOI among P. vivax patients of different symptoms, ages and genders. Similar patterns were also observed in P. falciparum except for one study site in Kenyan lowland areas with significantly higher MOI. The study used a novel method to evaluate Plasmodium MOI and molecular epidemiological patterns by long amplicon ultra-deep sequencing. The complexity of infections were similar among age groups, symptoms, genders, transmission settings (spatial heterogeneity), as well as over years (pre- vs. post-scale-up interventions). This study demonstrated that long amplicon deep sequencing is a useful tool to investigate multiplicity and molecular epidemiology of Plasmodium parasite infections.

Transmission blocking activity of a standardized neem (Azadirachta indica) seed extract on the rodent malaria parasite Plasmodium berghei in its vector Anopheles stephensi

PubMed Central

2010-01-01

Background The wide use of gametocytocidal artemisinin-based combination therapy (ACT) lead to a reduction of Plasmodium falciparum transmission in several African endemic settings. An increased impact on malaria burden may be achieved through the development of improved transmission-blocking formulations, including molecules complementing the gametocytocidal effects of artemisinin derivatives and/or acting on Plasmodium stages developing in the vector. Azadirachtin, a limonoid (tetranortriterpenoid) abundant in neem (Azadirachta indica, Meliaceae) seeds, is a promising candidate, inhibiting Plasmodium exflagellation in vitro at low concentrations. This work aimed at assessing the transmission-blocking potential of NeemAzal®, an azadirachtin-enriched extract of neem seeds, using the rodent malaria in vivo model Plasmodium berghei/Anopheles stephensi. Methods Anopheles stephensi females were offered a blood-meal on P. berghei infected, gametocytaemic BALB/c mice, treated intraperitoneally with NeemAzal, one hour before feeding. The transmission-blocking activity of the product was evaluated by assessing oocyst prevalence, oocyst density and capacity to infect healthy mice. To characterize the anti-plasmodial effects of NeemAzal® on early midgut stages, i.e. zygotes and ookinetes, Giemsa-stained mosquito midgut smears were examined. Results NeemAzal® completely blocked P. berghei development in the vector, at an azadirachtin dose of 50 mg/kg mouse body weight. The totally 138 examined, treated mosquitoes (three experimental replications) did not reveal any oocyst and none of the healthy mice exposed to their bites developed parasitaemia. The examination of midgut content smears revealed a reduced number of zygotes and post-zygotic forms and the absence of mature ookinetes in treated mosquitoes. Post-zygotic forms showed several morphological alterations, compatible with the hypothesis of an azadirachtin interference with the functionality of the microtubule organizing centres and with the assembly of cytoskeletal microtubules, which are both fundamental processes in Plasmodium gametogenesis and ookinete formation. Conclusions This work demonstrated in vivo transmission blocking activity of an azadirachtin-enriched neem seed extract at an azadirachtin dose compatible with 'druggability' requisites. These results and evidence of anti-plasmodial activity of neem products accumulated over the last years encourage to convey neem compounds into the drug discovery & development pipeline and to evaluate their potential for the design of novel or improved transmission-blocking remedies. PMID:20196858

Plasmodium falciparum ookinete expression of plasmepsin VII and plasmepsin X.

PubMed

Li, Fengwu; Bounkeua, Viengngeun; Pettersen, Kenneth; Vinetz, Joseph M

2016-02-24

Plasmodium invasion of the mosquito midgut is a population bottleneck in the parasite lifecycle. Interference with molecular mechanisms by which the ookinete invades the mosquito midgut is one potential approach to developing malaria transmission-blocking strategies. Plasmodium aspartic proteases are one such class of potential targets: plasmepsin IV (known to be present in the asexual stage food vacuole) was previously shown to be involved in Plasmodium gallinaceum infection of the mosquito midgut, and plasmepsins VII and plasmepsin X (not known to be present in the asexual stage food vacuole) are upregulated in Plasmodium falciparum mosquito stages. These (and other) parasite-derived enzymes that play essential roles during ookinete midgut invasion are prime candidates for transmission-blocking vaccines. Reverse transcriptase PCR (RT-PCR) was used to determine timing of P. falciparum plasmepsin VII (PfPM VII) and plasmepsin X (PfPM X) mRNA transcripts in parasite mosquito midgut stages. Protein expression was confirmed by western immunoblot and immunofluorescence assays (IFA) using anti-peptide monoclonal antibodies (mAbs) against immunogenic regions of PfPM VII and PfPM X. These antibodies were also used in standard membrane feeding assays (SMFA) to determine whether inhibition of these proteases would affect parasite transmission to mosquitoes. The Mann-Whitney U test was used to analyse mosquito transmission assay results. RT-PCR, western immunoblot and immunofluorescence assay confirmed expression of PfPM VII and PfPM X in mosquito stages. Whereas PfPM VII was expressed in zygotes and ookinetes, PfPM X was expressed in gametes, zygotes, and ookinetes. Antibodies against PfPM VII and PfPM X decreased P. falciparum invasion of the mosquito midgut when used at high concentrations, indicating that these proteases play a role in Plasmodium mosquito midgut invasion. Failure to generate genetic knockouts of these genes limited determination of the precise role of these proteases in parasite transmission but suggests that they are essential during the intraerythrocytic life cycle. PfPM VII and PfPM X are present in the mosquito-infective stages of P. falciparum. Standard membrane feeding assays demonstrate that antibodies against these proteins reduce the infectivity of P. falciparum for mosquitoes, suggesting their viability as transmission-blocking vaccine candidates. Further study of the role of these plasmepsins in P. falciparum biology is warranted.

Plasmodium prevalence and artemisinin-resistant falciparum malaria in Preah Vihear Province, Cambodia: a cross-sectional population-based study.

PubMed

Bosman, Philippe; Stassijns, Jorgen; Nackers, Fabienne; Canier, Lydie; Kim, Nimol; Khim, Saorin; Alipon, Sweet C; Chuor Char, Meng; Chea, Nguon; Dysoley, Lek; Van den Bergh, Rafael; Etienne, William; De Smet, Martin; Ménard, Didier; Kindermans, Jean-Marie

2014-10-06

Intensified efforts are urgently needed to contain and eliminate artemisinin-resistant Plasmodium falciparum in the Greater Mekong subregion. Médecins Sans Frontières plans to support the Ministry of Health in eliminating P. falciparum in an area with artemisinin resistance in the north-east of Cambodia. As a first step, the prevalence of Plasmodium spp. and the presence of mutations associated with artemisinin resistance were evaluated in two districts of Preah Vihear Province. A cross-sectional population-based study using a two-stage cluster sampling was conducted in the rural districts of Chhaeb and Chey Saen, from September to October 2013. In each district, 30 clusters of 10 households were randomly selected. In total, blood samples were collected for 1,275 participants in Chhaeb and 1,224 in Chey Saen. Prevalence of Plasmodium spp. was assessed by PCR on dried blood spots. Plasmodium falciparum positive samples were screened for mutations in the K13-propeller domain gene (PF3D7_1343700). The prevalence of Plasmodium spp. was estimated at 1.49% (95% CI 0.71-3.11%) in Chhaeb and 2.61% (95% CI 1.45-4.66%) in Chey Saen. Twenty-seven samples were positive for P. falciparum, giving a prevalence of 0.16% (95% CI 0.04-0.65) in Chhaeb and 2.04% (95% CI 1.04-3.99%) in Chey Saen. Only 4.0% of the participants testing positive presented with fever or history of fever. K13-propeller domain mutant type alleles (C580Y and Y493H) were found, only in Chey Saen district, in seven out of 11 P. falciparum positive samples with enough genetic material to allow testing. The overall prevalence of P. falciparum was low in both districts but parasites presenting mutations in the K13-propeller domain gene, strongly associated with artemisinin-resistance, are circulating in Chey Saen.The prevalence might be underestimated because of the absentees - mainly forest workers - and the workers of private companies who were not included in the study. These results confirm the need to urgently develop and implement targeted interventions to contain and eliminate P. falciparum malaria in this district before it spreads to other areas.

Mortality and pathology in birds due to Plasmodium (Giovannolaia) homocircumflexum infection, with emphasis on the exoerythrocytic development of avian malaria parasites.

PubMed

Ilgūnas, Mikas; Bukauskaitė, Dovilė; Palinauskas, Vaidas; Iezhova, Tatjana A; Dinhopl, Nora; Nedorost, Nora; Weissenbacher-Lang, Christiane; Weissenböck, Herbert; Valkiūnas, Gediminas

2016-05-04

Species of avian malaria parasites (Plasmodium) are widespread, but their virulence has been insufficiently investigated, particularly in wild birds. During avian malaria, several cycles of tissue merogony occur, and many Plasmodium spp. produce secondary exoerythrocytic meronts (phanerozoites), which are induced by merozoites developing in erythrocytic meronts. Phanerozoites markedly damage organs, but remain insufficiently investigated in the majority of described Plasmodium spp. Avian malaria parasite Plasmodium (Giovannolaia) homocircumflexum (lineage pCOLL4) is virulent and produces phanerozoites in domestic canaries Serinus canaria, but its pathogenicity in wild birds remains unknown. The aim of this study was to investigate the pathology caused by this infection in species of common European birds. One individual of Eurasian siskin Carduelis spinus, common crossbill Loxia curvirostra and common starling Sturnus vulgaris were exposed to P. homocircumflexum infection by intramuscular sub-inoculation of infected blood. The birds were maintained in captivity and parasitaemia was monitored until their death due to malaria. Brain, heart, lungs, liver, spleen, kidney, and a piece of breast muscle were examined using histology and chromogenic in situ hybridization (ISH) methods. All exposed birds developed malaria infection, survived the peak of parasitaemia, but suddenly died between 30 and 38 days post exposure when parasitaemia markedly decreased. Numerous phanerozoites were visible in histological sections of all organs and were particularly easily visualized after ISH processing. Blockage of brain capillaries with phanerozoites may have led to cerebral ischaemia, causing cerebral paralysis and is most likely the main reason of sudden death of all infected individuals. Inflammatory response was not visible around the brain, heart and muscle phanerozoites, and it was mild in parenchymal organs. The endothelial damage likely causes dysfunction and failure of parenchymal organs. Plasmodium homocircumflexum caused death of experimental passerine birds due to marked damage of organs by phanerozoites. Patterns of phanerozoites development and pathology were similar in all exposed birds. Mortality was reported when parasitaemia decreased or even turned into chronic stage, indicating that the light parasitaemia is not always indication of improved health during avian malaria. Application of traditional histological and ISH methods in parallel simplifies investigation of exoerythrocytic development and is recommended in avian malaria research.

Agglutination Assays of the Plasmodium falciparum-Infected Erythrocyte.

PubMed

Tan, Joshua; Bull, Peter C

2015-01-01

The agglutination assay is used to determine the ability of antibodies to recognize parasite variant antigens on the surface of Plasmodium falciparum-infected erythrocytes. In this technique, infected erythrocytes are selectively labelled with a DNA-binding fluorescent dye and mixed with antibodies of interest to allow antibody-surface antigen binding. Recognition of surface antigens by the antibodies can result in the formation of agglutinates containing multiple parasite-infected erythrocytes. These can be viewed and quantified using a fluorescence microscope.

Origin and Dissemination of Chloroquine-Resistant Plasmodium falciparum with Mutant pfcrt Alleles in the Philippines

PubMed Central

Chen, Nanhua; Wilson, Danny W.; Pasay, Cielo; Bell, David; Martin, Laura B.; Kyle, Dennis; Cheng, Qin

2005-01-01

The pfcrt allelic type and adjacent microsatellite marker type were determined for 82 Plasmodium falciparum isolates from the Philippines. Mutant pfcrt allelic types P1a and P2a/P2b were dominant in different locations. Microsatellite analysis revealed that P2a/P2b evolved independently in the Philippines, while P1a shared common ancestry with Papua New Guinea chloroquine-resistant parasites. PMID:15855538

Complement and Antibody-Mediated Enhancement of Erythrocyte Invasion by Plasmodium Falciparum

DTIC Science & Technology

2016-04-01

Waki et al., 1995; Yoneto et al., 2001). However, the doses of antibody in those studies were much higher, usually given in milligram amounts and...erythrocyte receptor for Plasmodium falciparum PfRh4 invasion ligand. Proc. Natl. Acad. Sci. U. S. A. 107, 17327–17332. Waki , S., Uehara, S., Kanbe, K...infections. J. Immunol. 126, 1826–1828. Wold Health Organization, 2013. World Malaria Report 2013 (Geneva). Yoneto, T., Waki , S., Takai, T., Tagawa, Y

[Morphology, biology and life-cycle of Plasmodium parasites].

PubMed

Hommel, Marcel

2007-10-01

Laveran first discovered that an infectious agent was responsible for malaria by using a simple microscope, without the assistance of specific stains. Our knowledge of the Plasmodium life cycle and cellular biology has progressed with each technological advance, from Romanovsky staining and histology to electron microscopy, immunocytochemistry, molecular methods and modern imaging techniques. The use of bird, primate and rodent models also made a major contribution, notably in the development of antimalarial drugs that are still in use today.

Anti-malarial effect of gum arabic

PubMed Central

2011-01-01

Background Gum Arabic (GA), a nonabsorbable nutrient from the exudate of Acacia senegal, exerts a powerful immunomodulatory effect on dendritic cells, antigen-presenting cells involved in the initiation of both innate and adaptive immunity. On the other hand GA degradation delivers short chain fatty acids, which in turn have been shown to foster the expression of foetal haemoglobin in erythrocytes. Increased levels of erythrocyte foetal haemoglobin are known to impede the intraerythrocytic growth of Plasmodium and thus confer some protection against malaria. The present study tested whether gum arabic may influence the clinical course of malaria. Methods Human erythrocytes were in vitro infected with Plasmodium falciparum in the absence and presence of butyrate and mice were in vivo infected with Plasmodium berghei ANKA by injecting parasitized murine erythrocytes (1 × 106) intraperitoneally. Half of the mice received gum arabic (10% in drinking water starting 10 days before the day of infection). Results According to the in vitro experiments butyrate significantly blunted parasitaemia only at concentrations much higher (3 mM) than those encountered in vivo following GA ingestion (<1 μM). According to the in vivo experiments the administration of gum arabic slightly but significantly decreased the parasitaemia and significantly extended the life span of infected mice. Discussion GA moderately influences the parasitaemia and survival of Plasmodium-infected mice. The underlying mechanism remained, however, elusive. Conclusions Gum arabic favourably influences the course of murine malaria. PMID:21599958

[Therapeutic response of Plasmodium vivax to chloroquine in Bolivia].

PubMed

Añez, Arletta; Navarro-Costa, Dennis; Yucra, Omar; Garnica, Cecilia; Melgar, Viviana; Moscoso, Manuel; Arteaga, Ricardo; Nakao, Gladys

2012-01-01

Knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance. The therapeutic efficacy of chloroquine as treatment was evaluated for uncomplicated Plasmodium vivax malaria in Bolivia. An in vivo efficacy study of chloroquine was undertaken in three regions of Bolivia--Riberalta, Guayaramerín and Yacuiba. Two hundred and twenty-three patients (84, 80, and 59 in the three regions, respectively) aged over 5 years old were administered with chloroquine (25 mg/kg/three days) and followed for 28 days. Blood levels of chloroquine and desethylchloroquine were measured on day 2 and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan and Meier survival analysis. The mean parasitemias (asexual) on day 0 were 6,147 parasites/μl of blood in the Riberalta population, 4,251 in Guayaramerín and 5,214 in Yacuiba. The average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817, and 815 ng/ml, respectively. No treatment failures were observed in Yacuiba, whereas in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia. Resistance of Plasmodium vivax to chloroquine was not demonstrated in three regions of Bolivia.

Hemosporidian parasites in forest birds from Venezuela: genetic lineage analyses.

PubMed

Mijares, Alfredo; Rosales, Romel; Silva-Iturriza, Adriana

2012-09-01

Avian hemosporidian parasites of the genera Haemoproteus, Plasmodium, and Leucocytozoon are transmitted by different dipteran vectors. In the present work, we looked for the presence of these parasites in 47 birds from 12 families, which were sampled in the migratory corridor Paso de Portachuelo, located at the Henri Pittier National Park, Venezuela. The presence of the parasites was evidenced by amplification of a region of 471 bp of their cytochrome b gene. This region of the marker presents enough polymorphism to identify most of the mitochondrial lineages. Therefore, the obtained amplicons were sequenced, not only to identify the genus of the parasites sampled, but also to analyze their genetic diversity in the study area. The overall parasite prevalence was low (11%). We reported, for the first time, Plasmodium in birds of the species Formicarius analis and Chamaeza campanisona (Formicariidae) and Haemoproteus in Geotrygon linearis (Columbidae). A phylogenetic tree was generated using the Haemoproteus, Plasmodium, and Leucocytozoon sequences obtained in this study, together with representative sequences from previous studies. The highest genetic diversities between the two Haemoproteus lineages (11.70%) and among the three Plasmodium lineages (7.86%) found in this study are also similar to those found when lineages reported in the literature were used. These results indicate that in the migratory corridor Paso de Portachuleo, representative parasite lineages are found, making this location an attractive location for future studies.

A seroprevalence and descriptive epidemiological study of malaria among Indian tribes of the Amazon basin of Brazil.

PubMed

de Arruda, M E; Aragaki, C; Gagliardi, F; Haile, R W

1996-04-01

Data on the seroprevalences of Plasmodium falciparum, P. vivax, and P. malariae in four isolated Indian tribes of the Amazon basin in Brazil, as determined by IFAT, were re-analysed. Age-, sex- and tribe-specific geometric mean antibody titres and externally standardized prevalence ratios were calculated for each parasite species. Correlation coefficients and prevalence odds ratios were also calculated for multiple infections with different combinations of the three Plasmodium species. Titres of all but one of the antibodies studied were similar in males and females; titres of antibodies to the blood stages of P. malariae were slightly higher in females than in males. Titres of antibodies to all three Plasmodium species increased with subject age, and this age effect was not confounded by sex or tribal differences. There were striking differences between tribes, with the Parakana tribe having relatively low titres of antibodies against P. falciparum and P. malariae; these tribal effects were not confounded by sex or age differences between tribes. The results indicate that conditions conductive to the transmission of P. malariae exist in this region of the Amazon. The potential for zoonotic transmission of P. brasilianum, a parasite of monkeys which is morphologically similar to P. malarie, and the generally high rates of seropositivity to all three species of Plasmodium indicate that control measures which are adequate and applicable to the region studied need to be developed.

A T-cell response to a liver-stage Plasmodium antigen is not boosted by repeated sporozoite immunizations

PubMed Central

Murphy, Sean C.; Kas, Arnold; Stone, Brad C.; Bevan, Michael J.

2013-01-01

Development of an antimalarial subunit vaccine inducing protective cytotoxic T lymphocyte (CTL)-mediated immunity could pave the way for malaria eradication. Experimental immunization with sporozoites induces this type of protective response, but the extremely large number of proteins expressed by Plasmodium parasites has so far prohibited the identification of sufficient discrete T-cell antigens to develop subunit vaccines that produce sterile immunity. Here, using mice singly immunized with Plasmodium yoelii sporozoites and high-throughput screening, we identified a unique CTL response against the parasite ribosomal L3 protein. Unlike CTL responses to the circumsporozoite protein (CSP), the population of L3-specific CTLs was not expanded by multiple sporozoite immunizations. CSP is abundant in the sporozoite itself, whereas L3 expression does not increase until the liver stage. The response induced by a single immunization with sporozoites reduces the parasite load in the liver so greatly during subsequent immunizations that L3-specific responses are only generated during the primary exposure. Functional L3-specific CTLs can, however, be expanded by heterologous prime-boost regimens. Thus, although repeat sporozoite immunization expands responses to preformed antigens like CSP that are present in the sporozoite itself, this immunization strategy may not expand CTLs targeting parasite proteins that are synthesized later. Heterologous strategies may be needed to increase CTL responses across the entire spectrum of Plasmodium liver-stage proteins. PMID:23530242

Plant hairy root cultures as plasmodium modulators of the slime mold emergent computing substrate Physarum polycephalum.

PubMed

Ricigliano, Vincent; Chitaman, Javed; Tong, Jingjing; Adamatzky, Andrew; Howarth, Dianella G

2015-01-01

Roots of the medicinal plant Valeriana officinalis are well-studied for their various biological activities. We applied genetically transformed V. officinalis root biomass to exert control of Physarum polycephalum, an amoeba-based emergent computing substrate. The plasmodial stage of the P. polycephalum life cycle constitutes a single, multinucleate cell visible by unaided eye. The plasmodium modifies its network of oscillating protoplasm in response to spatial configurations of attractants and repellents, a behavior that is interpreted as biological computation. To program the computing behavior of P. polycephalum, a diverse and sustainable library of plasmodium modulators is required. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically stable source of bioactive compounds. Adventitious roots were induced on in vitro V. officinalis plants following infection with A. rhizogenes. A single hairy root clone was selected for massive propagation and the biomass was characterized in P. polycephalum chemotaxis, maze-solving, and electrical activity assays. The Agrobacterium-derived roots of V. officinalis elicited a positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy root biomass stimulated the oscillation patterns of slime mold's surface electrical activity. We propose that manipulation of P. polycephalum with the plant root culture platform can be applied to the development of slime mold microfluidic devices as well as future models for engineering the plant rhizosphere.

Plant hairy root cultures as plasmodium modulators of the slime mold emergent computing substrate Physarum polycephalum

PubMed Central

Ricigliano, Vincent; Chitaman, Javed; Tong, Jingjing; Adamatzky, Andrew; Howarth, Dianella G.

2015-01-01

Roots of the medicinal plant Valeriana officinalis are well-studied for their various biological activities. We applied genetically transformed V. officinalis root biomass to exert control of Physarum polycephalum, an amoeba-based emergent computing substrate. The plasmodial stage of the P. polycephalum life cycle constitutes a single, multinucleate cell visible by unaided eye. The plasmodium modifies its network of oscillating protoplasm in response to spatial configurations of attractants and repellents, a behavior that is interpreted as biological computation. To program the computing behavior of P. polycephalum, a diverse and sustainable library of plasmodium modulators is required. Hairy roots produced by genetic transformation with Agrobacterium rhizogenes are a metabolically stable source of bioactive compounds. Adventitious roots were induced on in vitro V. officinalis plants following infection with A. rhizogenes. A single hairy root clone was selected for massive propagation and the biomass was characterized in P. polycephalum chemotaxis, maze-solving, and electrical activity assays. The Agrobacterium-derived roots of V. officinalis elicited a positive chemotactic response and augmented maze-solving behavior. In a simple plasmodium circuit, introduction of hairy root biomass stimulated the oscillation patterns of slime mold's surface electrical activity. We propose that manipulation of P. polycephalum with the plant root culture platform can be applied to the development of slime mold microfluidic devices as well as future models for engineering the plant rhizosphere. PMID:26236301

The serine protease homolog CLIPA14 modulates the intensity of the immune response in the mosquito Anopheles gambiae

PubMed Central

Nakhleh, Johnny; Christophides, George K.; Osta, Mike A.

2017-01-01

Clip domain serine protease homologs (SPHs) are positive and negative regulators of Anopheles gambiae immune responses mediated by the complement-like protein TEP1 against Plasmodium malaria parasites and other microbial infections. We have previously reported that the SPH CLIPA2 is a negative regulator of the TEP1-mediated response by showing that CLIPA2 knockdown (kd) enhances mosquito resistance to infections with fungi, bacteria, and Plasmodium parasites. Here, we identify another SPH, CLIPA14, as a novel regulator of mosquito immunity. We found that CLIPA14 is a hemolymph protein that is rapidly cleaved following a systemic infection. CLIPA14 kd mosquitoes elicited a potent melanization response against Plasmodium berghei ookinetes and exhibited significantly increased resistance to Plasmodium infections as well as to systemic and oral bacterial infections. The activity of the enzyme phenoloxidase, which initiates melanin biosynthesis, dramatically increased in the hemolymph of CLIPA14 kd mosquitoes in response to systemic bacterial infections. Ookinete melanization and hemolymph phenoloxidase activity were further increased after cosilencing CLIPA14 and CLIPA2, suggesting that these two SPHs act in concert to control the melanization response. Interestingly, CLIPA14 RNAi phenotypes and its infection-induced cleavage were abolished in a TEP1 loss-of-function background. Our results suggest that a complex network of SPHs functions downstream of TEP1 to regulate the melanization reaction. PMID:28928218

Functional Antibodies against VAR2CSA in Nonpregnant Populations from Colombia Exposed to Plasmodium falciparum and Plasmodium vivax

PubMed Central

Doritchamou, Justin; Arango, Eliana M.; Cabrera, Ana; Arroyo, Maria Isabel; Kain, Kevin C.; Ndam, Nicaise Tuikue; Maestre, Amanda

2014-01-01

In pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women. However, in Colombia, we detected antibodies against multiple constructs of VAR2CSA among men and children with acute P. falciparum and Plasmodium vivax infection. The majority of men and children (>60%) had high levels of IgGs against three recombinant domains of VAR2CSA: DBL5ε, DBL3X, and ID1-ID2. Surprisingly, these antibodies were observed only in pregnant women, men, and children exposed either to P. falciparum or to P. vivax. Moreover, the anti-VAR2CSA antibodies are of high avidity and efficiently inhibit adherence of infected red blood cells to chondroitin sulfate A in vitro, suggesting that they are specific and functional. These unexpected results suggest that there may be genotypic or phenotypic differences in the parasites of this region or in the host response to either P. falciparum or P. vivax infection outside pregnancy. These findings may hold significant clinical relevance to the pathophysiology and outcome of malaria infections in this region. PMID:24686068

Grammomys surdaster, the Natural Host for Plasmodium berghei Parasites, as a Model to Study Whole-Organism Vaccines Against Malaria.

PubMed

Conteh, Solomon; Anderson, Charles; Lambert, Lynn; Orr-Gonzalez, Sachy; Herrod, Jessica; Robbins, Yvette L; Carter, Dariyen; Karhemere, Stomy Bin Shamamba; Pyana, Pati; Büscher, Philippe; Duffy, Patrick E

2017-04-01

AbstractInbred mice are commonly used to test candidate malaria vaccines, but have been unreliable for predicting efficacy in humans. To establish a more rigorous animal model, we acquired African woodland thicket rats of the genus Grammomys , the natural hosts for Plasmodium berghei . Thicket rats were acquired and identified as Grammomys surdaster by skull and teeth measurements and mitochondrial DNA genotyping. Herein, we demonstrate that thicket rats are highly susceptible to infection by P. berghei , and moderately susceptible to Plasmodium yoelii and Plasmodium chabaudi : 1-2 infected mosquito bites or 25-100 sporozoites administered by intravenous injection consistently resulted in patent parasitemia with P. berghei , and resulted in patent parasitemia with P. yoelii and P. chabaudi strains for at least 50% of animals. We then assessed efficacy of whole-organism vaccines to induce sterile immunity, and compared the thicket rat model to conventional mouse models. Using P. berghei ANKA radiation-attenuated sporozoites, and P. berghei ANKA and P. yoelii chemoprophylaxis vaccination approaches, we found that standard doses of vaccine sufficient to protect laboratory mice for a long duration against malaria challenge, are insufficient to protect thicket rats, which require higher doses of vaccine to achieve even short-term sterile immunity. Thicket rats may offer a more stringent and pertinent model for evaluating whole-organism vaccines.

Assessing subunit dependency of the Plasmodium proteasome using small molecule inhibitors and active site probes.

PubMed

Li, Hao; van der Linden, Wouter A; Verdoes, Martijn; Florea, Bogdan I; McAllister, Fiona E; Govindaswamy, Kavitha; Elias, Joshua E; Bhanot, Purnima; Overkleeft, Herman S; Bogyo, Matthew

2014-08-15

The ubiquitin-proteasome system (UPS) is a potential pathway for therapeutic intervention for pathogens such as Plasmodium, the causative agent of malaria. However, due to the essential nature of this proteolytic pathway, proteasome inhibitors must avoid inhibition of the host enzyme complex to prevent toxic side effects. The Plasmodium proteasome is poorly characterized, making rational design of inhibitors that induce selective parasite killing difficult. In this study, we developed a chemical probe that labels all catalytic sites of the Plasmodium proteasome. Using this probe, we identified several subunit selective small molecule inhibitors of the parasite enzyme complex. Treatment with an inhibitor that is specific for the β5 subunit during blood stage schizogony led to a dramatic decrease in parasite replication while short-term inhibition of the β2 subunit did not affect viability. Interestingly, coinhibition of both the β2 and β5 catalytic subunits resulted in enhanced parasite killing at all stages of the blood stage life cycle and reduced parasite levels in vivo to barely detectable levels. Parasite killing was achieved with overall low host toxicity, something that has not been possible with existing proteasome inhibitors. Our results highlight differences in the subunit dependency of the parasite and human proteasome, thus providing a strategy for development of potent antimalarial drugs with overall low host toxicity.

Pernicious plans revealed: Plasmodium falciparum genome wide expression analysis.

PubMed

Llinás, Manuel; DeRisi, Joseph L

2004-08-01

The asexual intraerythrocytic developmental cycle (IDC) of Plasmodium falciparum is responsible for the majority of the clinical manifestations of malaria in humans. Although malaria has been studied for over a century, the elucidation of the full genome sequence of P. falciparum has now allowed for in-depth studies of gene expression throughout the entire intraerythrocytic stage. As the mainstays of anti-malarial chemotherapy become increasingly ineffective, we need a deeper understanding of fundamental plasmodial bioregulatory mechanisms to successfully subvert them. Recent gene expression studies have begun to examine different aspects of the IDC and are providing key insights into the basic mechanisms of Plasmodium gene regulation and are helping to define gene functions. However, to date, no transcription factor has been fully characterized from Plasmodium and the definitive identification of cis-acting regulatory elements along with their corresponding trans-acting partners is still lacking. The characterization of the transcriptome of P. falciparum is the first major step towards the understanding of the genome wide regulation of gene expression in this parasite. IDC expression data for almost every gene in the P. falciparum genome can now be publicly queried at and. The results of these studies suggest promising leads for identifying novel targets for anti-malarial therapeutics and vaccines in addition to providing a solid foundation for the ongoing elucidation of plasmodial gene expression.

Reconstructing the Qo Site of Plasmodium falciparum bc 1 Complex in the Yeast Enzyme

PubMed Central

Vallières, Cindy; Fisher, Nicholas; Meunier, Brigitte

2013-01-01

The bc 1 complex of the mitochondrial respiratory chain is essential for Plasmodium falciparum proliferation, the causative agent of human malaria. Therefore, this enzyme is an attractive target for antimalarials. However, biochemical investigations of the parasite enzyme needed for the study of new drugs are challenging. In order to facilitate the study of new compounds targeting the enzyme, we are modifying the inhibitor binding sites of the yeast Saccharomyces cerevisiae to generate a complex that mimics the P. falciparum enzyme. In this study we focused on its Qo pocket, the site of atovaquone binding which is a leading antimalarial drug used in treatment and causal prophylaxis. We constructed and studied a series of mutants with modified Qo sites where yeast residues have been replaced by P. falciparum equivalents, or, for comparison, by human equivalents. Mitochondria were prepared from the yeast Plasmodium-like and human-like Qo mutants. We measured the bc 1 complex sensitivity to atovaquone, azoxystrobin, a Qo site targeting fungicide active against P. falciparum and RCQ06, a quinolone-derivative inhibitor of P. falciparum bc 1 complex.The data obtained highlighted variations in the Qo site that could explain the differences in inhibitor sensitivity between yeast, plasmodial and human enzymes. We showed that the yeast Plasmodium-like Qo mutants could be useful and easy-to-use tools for the study of that class of antimalarials. PMID:23951230

Occurrence of avian Plasmodium and West Nile virus in culex species in Wisconsin

USGS Publications Warehouse

Hughes, T.; Irwin, P.; Hofmeister, E.; Paskewitz, S.M.

2010-01-01

The occurrence of multiple pathogens in mosquitoes and birds could affect the dynamics of disease transmission. We collected adult Culex pipiens and Cx. restuans (Cx. pipiens/restuans hereafter) from sites in Wisconsin and tested them for West Nile virus (WNV) and for avian malaria (Plasmodium). Gravid Cx. pipiens/restuans were tested for WNV using a commercial immunoassay, the RAMP?? WNV test, and positive results were verified by reverse transcriptasepolymerase chain reaction. There were 2 WNV-positive pools of Cx. pipiens/restuans in 2006 and 1 in 2007. Using a bias-corrected maximum likelihood estimation, the WNV infection rate for Cx. pipiens/restuans was 5.48/1,000 mosquitoes in 2006 and 1.08/1,000 mosquitoes in 2007. Gravid Cx. pipiens or Cx. restuans were tested individually for avian Plasmodium by a restriction enzymebased assay. Twelve mosquitoes were positive for avian Plasmodium (10.0), 2 were positive for Haemoproteus, and 3 were positive for Leucocytozoon. There were 4 mixed infections, with mosquitoes positive for >1 of the hemosporidian parasites. This work documents a high rate of hemosporidian infection in Culex spp. and illustrates the potential for co-infections with other arboviruses in bird-feeding mosquitoes and their avian hosts. In addition, hemosporidian infection rates may be a useful tool for investigating the ecological dynamics of Culex/avian interactions. ?? 2010 by The American Mosquito Control Association, Inc.

Alterations in cytokines and haematological parameters during the acute and convalescent phases of Plasmodium falciparum and Plasmodium vivax infections.

PubMed

Rodrigues-da-Silva, Rodrigo Nunes; Lima-Junior, Josué da Costa; Fonseca, Bruna de Paula Fonseca e; Antas, Paulo Renato Zuquim; Baldez, Arlete; Storer, Fabio Luiz; Santos, Fátima; Banic, Dalma Maria; Oliveira-Ferreira, Joseli de

2014-04-01

Haematological and cytokine alterations in malaria are a broad and controversial subject in the literature. However, few studies have simultaneously evaluated various cytokines in a single patient group during the acute and convalescent phases of infection. The aim of this study was to sequentially characterise alterations in haematological patters and circulating plasma cytokine and chemokine levels in patients infected with Plasmodium vivax or Plasmodium falciparum from a Brazilian endemic area during the acute and convalescent phases of infection. During the acute phase, thrombocytopaenia, eosinopaenia, lymphopaenia and an increased number of band cells were observed in the majority of the patients. During the convalescent phase, the haematologic parameters returned to normal. During the acute phase, P. vivax and P. falciparum patients had significantly higher interleukin (IL)-6, IL-8, IL-17, interferon-γ, tumour necrosis factor (TNF)-α, macrophage inflammatory protein-1β and granulocyte-colony stimulating factor levels than controls and maintained high levels during the convalescent phase. IL-10 was detected at high concentrations during the acute phase, but returned to normal levels during the convalescent phase. Plasma IL-10 concentration was positively correlated with parasitaemia in P. vivax and P. falciparum-infected patients. The same was true for the TNF-α concentration in P. falciparum-infected patients. Finally, the haematological and cytokine profiles were similar between uncomplicated P. falciparum and P. vivax infections.

Genetic Diversity and Host Specificity Varies across Three Genera of Blood Parasites in Ducks of the Pacific Americas Flyway

PubMed Central

Reeves, Andrew B.; Smith, Mathew M.; Meixell, Brandt W.; Fleskes, Joseph P; Ramey, Andrew M.

2015-01-01

Birds of the order Anseriformes, commonly referred to as waterfowl, are frequently infected by Haemosporidia of the genera Haemoproteus, Plasmodium, and Leucocytozoon via dipteran vectors. We analyzed nucleotide sequences of the Cytochrome b (Cytb) gene from parasites of these genera detected in six species of ducks from Alaska and California, USA to characterize the genetic diversity of Haemosporidia infecting waterfowl at two ends of the Pacific Americas Flyway. In addition, parasite Cytb sequences were compared to those available on a public database to investigate specificity of genetic lineages to hosts of the order Anseriformes. Haplotype and nucleotide diversity of Haemoproteus Cytb sequences was lower than was detected for Plasmodium and Leucocytozoon parasites. Although waterfowl are presumed to be infected by only a single species of Leucocytozoon, L. simondi, diversity indices were highest for haplotypes from this genus and sequences formed five distinct clades separated by genetic distances of 4.9%–7.6%, suggesting potential cryptic speciation. All Haemoproteus and Leucocytozoon haplotypes derived from waterfowl samples formed monophyletic clades in phylogenetic analyses and were unique to the order Anseriformes with few exceptions. In contrast, waterfowl-origin Plasmodium haplotypes were identical or closely related to lineages found in other avian orders. Our results suggest a more generalist strategy for Plasmodium parasites infecting North American waterfowl as compared to those of the genera Haemoproteus and Leucocytozoon. PMID:25710468

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens.

PubMed

Ateba-Ngoa, Ulysse; Jones, Sophie; Zinsou, Jeannot Fréjus; Honkpehedji, Josiane; Adegnika, Ayola Akim; Agobe, Jean-Claude Dejon; Massinga-Loembe, Marguerite; Mordmüller, Benjamin; Bousema, Teun; Yazdanbakhsh, Maria

2016-08-03

Infections with helminths and Plasmodium spp. overlap in their geographical distribution. It has been postulated that helminth infections may influence malarial transmission by altering Plasmodium falciparum gametocytogenesis. This cross-sectional study assessed the effect of helminth infections on P. falciparum gametocyte carriage and on humoral immune responses to sexual stage antigens in Gabon. Schistosoma haematobium and filarial infections as well as P. falciparum asexual forms and gametocyte carriage were determined. The antibody responses measured were to sexual (Pfs230, Pfs48/45) and asexual P. falciparum antigens (AMA1, MSP1, and GLURP). A total of 287 subjects were included. The prevalence of microscopically detectable P. falciparum asexual parasites was higher in S. haematobium-infected subjects in comparison to their uninfected counterparts (47% versus 26%, P = 0.003), but this was not different when filarial infections were considered. Plasmodium falciparum gametocyte carriage was similar between Schistosoma- or filaria-infected and uninfected subjects. We observed a significant decrease of Pfs48/45 immunoglobulin G titer in S. haematobium-infected subjects (P = 0.037), whereas no difference was seen for Pfs230 antibody titer, nor for antibodies to AMA1, MSP1, or GLURP. Our findings suggest an effect of S. haematobium on antibody responses to some P. falciparum gametocyte antigens that may have consequences for transmission-blocking immunity. © The American Society of Tropical Medicine and Hygiene.

A paper and plastic device for the combined isothermal amplification and lateral flow detection of Plasmodium DNA.

PubMed

Cordray, Michael S; Richards-Kortum, Rebecca R

2015-11-26

Isothermal amplification techniques are emerging as a promising method for malaria diagnosis since they are capable of detecting extremely low concentrations of parasite target while mitigating the need for infrastructure and training required by other nucleic acid based tests. Recombinase polymerase amplification (RPA) is promising for further development since it operates in a short time frame (<30 min) and produces a product that can be visually detected on a lateral flow dipstick. A self-sealing paper and plastic system that performs both the amplification and detection of a malaria DNA sequence is presented. Primers were designed using the NCBI nBLAST tools and screened using gel electrophoresis. Paper and plastic devices were prototyped using commercial design software and parts were cut using a laser cutter and assembled by hand. Synthetic copies of the Plasmodium 18S gene were spiked into solution and used as targets for the RPA reaction. To test the performance of the device the same samples spiked with synthetic target were run in parallel both in the paper and plastic devices and using conventional bench top methods. Novel RPA primers were developed that bind to sequences present in the four species of Plasmodium which infect humans. The paper and plastic devices were found to be capable of detecting as few as 5 copies/µL of synthetic Plasmodium DNA (50 copies total), comparable to the same reaction run on the bench top. The devices produce visual results in an hour, cost approximately $1, and are self-contained once the device is sealed. The device was capable of carrying out the RPA reaction and detecting meaningful amounts of synthetic Plasmodium DNA in a self-sealing and self-contained device. This device may be a step towards making nucleic acid tests more accessible for malaria detection.

Efficacy and safety of artemisinin combination therapy (ACT) for non-falciparum malaria: a systematic review.

PubMed

Visser, Benjamin J; Wieten, Rosanne W; Kroon, Daniëlle; Nagel, Ingeborg M; Bélard, Sabine; van Vugt, Michèle; Grobusch, Martin P

2014-11-26

Artemisinin combination therapy (ACT) is recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria, whereas chloroquine is still commonly used for the treatment of non-falciparum species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae). A more simplified, more uniform treatment approach across all malaria species is worthwhile to be considered both in endemic areas and for malaria as an imported condition alike. A PROSPERO-registered systematic review to determine the efficacy and safety of ACT for the treatment of non-falciparum malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to November 2014. The literature search identified 986 reports; 40 publications were found eligible for inclusion, all of them on non-falciparum malaria in endemic areas. Most evidence was available for P. vivax (n = 35). Five clinical trials in total were identified evaluating ACT for P. ovale, P. malariae and Plasmodium knowlesi. Most ACT presentations have high efficacy against P. vivax parasites; artemisinin-based combinations have shorter parasite and fever clearance times compared to chloroquine. ACT is as effective as chloroquine in preventing recurrent parasitaemia before day 28. Artemisinin-based combinations with long half-lives show significantly fewer recurrent parasitaemia up to day 63. The limited evidence available supports both the use of chloroquine and an ACT for P. ovale and P. malariae. ACT seems to be preferable for optimal treatment of P. knowlesi. ACT is at least equivalent to chloroquine in effectively treating non-falciparum malaria. These findings may facilitate development of simplified protocols for treating all forms of malaria with ACT, including returning travellers. Obtaining comprehensive efficacy and safety data on ACT use for non-falciparum species particularly for P. ovale, P. malariae and P. knowlesi should be a research priority. CRD42014009103.

Prevalence of Plasmodium falciparum and non-P. falciparum infections in a highland district in Ghana, and the influence of HIV and sickle cell disease.

PubMed

Owusu, Ewurama D A; Brown, Charles A; Grobusch, Martin P; Mens, Petra

2017-04-24

In the past two decades, there has been a reported decline in malaria in Ghana and the rest of the world; yet it remains the number one cause of mortality and morbidity. Human immuno-deficiency virus (HIV) and sickle cell disease (SCD) share a common geographical space with malaria in sub-Saharan Africa and an interaction between these three conditions has been suggested. This study determined the Plasmodium falciparum and non-P. falciparum status of symptomatic and non-symptomatic residents of Mpraeso in the highlands of Kwahu-South district of Ghana based on evidence of current national decline. The influence of HIV and SCD on malaria was also determined. Participants were 354 symptomatic patients visiting the Kwahu Government Hospital and 360 asymptomatic residents of the district capital. This cross-sectional study was conducted during the minor rainy season (October-December 2014). Rapid diagnostic tests (RDT), blood film microscopy and real-time polymerase chain reaction assessment of blood were done. Participants who tested positive with RDT were treated with artemisinin-based combination therapy; and assessment of venous blood was repeated 7 days after treatment. HIV screening and haemoglobin genotyping was done. Univariate and multivariate regression analysis was used to determine the influence of SCD and HIV. Plasmodium falciparum was prevalent at 124/142 (87.3%). Plasmodium malariae was the only non-falciparum species detected at 18/142 (12.7%). HIV and SCD did not significantly increase odds of malaria infection. However, the use of ITN and recent anti-malarial intake significantly decreased the odds of being malaria infected by 0.45-fold and 0.46-fold respectively. Plasmodium falciparum and P. malariae infection are the prevailing species in the study area; albeit varying from the national average. HIV and SCD were not associated with the risk of having malaria.

Basal body structure and composition in the apicomplexans Toxoplasma and Plasmodium.

PubMed

Francia, Maria E; Dubremetz, Jean-Francois; Morrissette, Naomi S

2015-01-01

The phylum Apicomplexa encompasses numerous important human and animal disease-causing parasites, including the Plasmodium species, and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. Apicomplexans proliferate by asexual replication and can also undergo sexual recombination. Most life cycle stages of the parasite lack flagella; these structures only appear on male gametes. Although male gametes (microgametes) assemble a typical 9+2 axoneme, the structure of the templating basal body is poorly defined. Moreover, the relationship between asexual stage centrioles and microgamete basal bodies remains unclear. While asexual stages of Plasmodium lack defined centriole structures, the asexual stages of Toxoplasma and closely related coccidian apicomplexans contain centrioles that consist of nine singlet microtubules and a central tubule. There are relatively few ultra-structural images of Toxoplasma microgametes, which only develop in cat intestinal epithelium. Only a subset of these include sections through the basal body: to date, none have unambiguously captured organization of the basal body structure. Moreover, it is unclear whether this basal body is derived from pre-existing asexual stage centrioles or is synthesized de novo. Basal bodies in Plasmodium microgametes are thought to be synthesized de novo, and their assembly remains ill-defined. Apicomplexan genomes harbor genes encoding δ- and ε-tubulin homologs, potentially enabling these parasites to assemble a typical triplet basal body structure. Moreover, the UNIMOD components (SAS6, SAS4/CPAP, and BLD10/CEP135) are conserved in these organisms. However, other widely conserved basal body and flagellar biogenesis elements are missing from apicomplexan genomes. These differences may indicate variations in flagellar biogenesis pathways and in basal body arrangement within the phylum. As apicomplexan basal bodies are distinct from their metazoan counterparts, it may be possible to selectively target parasite structures in order to inhibit microgamete motility which drives generation of genetic diversity in Toxoplasma and transmission for Plasmodium.

Prevalence and Predictors of Asymptomatic Malaria Parasitemia among Pregnant Women in the Rural Surroundings of Arbaminch Town, South Ethiopia

PubMed Central

Nega, Desalegn; Dana, Daniel; Tefera, Tamirat; Eshetu, Teferi

2015-01-01

Background In Sub-Saharan African countries, including Ethiopia, malaria in pregnancy is a major public health threat which results in significant morbidities and mortalities among pregnant women and their fetuses. In malaria endemic areas, Plasmodium infections tend to remain asymptomatic yet causing significant problems like maternal anemia, low birth weight, premature births, and still birth. This study was conducted to determine the prevalence and predictors of asymptomatic Plasmodium infection among pregnant women in the rural surroundings of Arba Minch Town, Southern Ethiopia. Methods A community based cross-sectional study comprising multistage sampling was conducted between April and June, 2013. Socio-demographic data were collected by using a semi-structured questionnaire. Plasmodium infection was diagnosed by using Giemsa-stained blood smear microscopy and a rapid diagnostic test (SD BIOLINE Malaria Ag Pf/Pv POCT, standard diagnostics, inc., Korea). Results Of the total 341 pregnant women participated in this study, 9.1% (31/341) and 9.7% (33/341) were confirmed to be infected with Plasmodium species by microscopy and rapid diagnostic tests (RDTs), respectively. The geometric mean of parasite density was 2392 parasites per microliter (μl); 2275/ μl for P. falciparum and 2032/ μl for P. vivax. Parasitemia was more likely to occur in primigravidae (Adjusted odds ratio (AOR): 9.4, 95% confidence interval (CI): 4.3–60.5), secundigravidae (AOR: 6.3, 95% CI: 2.9–27.3), using insecticide treated bed net (ITN) sometimes (AOR: 3.2, 95% CI: 1.8- 57.9), not using ITN at all (AOR: 4.6, 95% CI: 1.4–14.4) compared to multigravidae and using ITN always, respectively. Conclusion Asymptomatic malaria in this study is low compared to other studies’ findings. Nevertheless, given the high risk of malaria during pregnancy, pregnant women essentially be screened for asymptomatic Plasmodium infection and be treated promptly via the antenatal care (ANC) services. PMID:25849587

The use of insecticide-treated nets for reducing malaria morbidity among children aged 6-59 months, in an area of high malaria transmission in central Côte d'Ivoire

PubMed Central

2010-01-01

Background Long-lasting insecticidal nets (LLINs) are an important tool for controlling malaria. Much attention has been devoted to determine both the effect of LLINs on the reduction of Plasmodium infection rate and on clinically-confirmed malaria cases in sub-Saharan Africa. We carried out an epidemiological study to investigate whether LLINs impact on Plasmodium prevalence rate and the proportion of clinically-confirmed malaria cases, in five villages in the district of Toumodi, central Côte d'Ivoire. Methods From April 2007 to November 2008, a community-based malaria control programme was implemented in the study villages, which involved large-scale distribution of LLINs, and training and sensitization activities within the community. We determined the effect of this programme on Plasmodium prevalence rate, clinically-confirmed malaria cases and proportion of high parasitaemia rates in children aged 6-59 months through a series of cross-sectional surveys starting in April 2007 and repeated once every 6 months. Results We observed a significant decrease in the mean P. falciparum prevalence rate from April 2007 to April 2008 (p = 0.029). An opposite trend was observed from November 2007 to November 2008 when P. falciparum prevalence rate increased significantly (p = 0.003). Highly significant decreases in the proportions of clinical malaria cases were observed between April 2007 and April 2008 (p < 0.001), and between November 2007 and November 2008 (p = 0.001). Conclusions Large-scale distribution of LLINs, accompanied by training and sensitization activities, significantly reduced Plasmodium prevalence rates among young children in the first year of the project, whereas overall clinical malaria rates dropped over the entire 18-month project period. A decrease in community motivation to sleep under bed nets, perhaps along with changing patterns of malaria transmission, might explain the observed increase in the Plasmodium prevalence rate between November 2007 and November 2008. PMID:20860829

Real-time polymerase chain reaction assay for the rapid detection and characterization of chloroquine-resistant Plasmodium falciparum malaria in returned travelers.

PubMed

Farcas, Gabriella A; Soeller, Rainer; Zhong, Kathleen; Zahirieh, Alireza; Kain, Kevin C

2006-03-01

Imported drug-resistant malaria is a growing problem in industrialized countries. Rapid and accurate diagnosis is essential to prevent malaria-associated mortality in returned travelers. However, outside of a limited number of specialized centers, the microscopic diagnosis of malaria is slow, unreliable, and provides little information about drug resistance. Molecular diagnostics have the potential to overcome these limitations. We developed and evaluated a rapid, real-time polymerase chain reaction (PCR) assay to detect Plasmodium falciparum malaria and chloroquine (CQ)-resistance determinants in returned travelers who are febrile. A real-time PCR assay based on detection of the K76T mutation in PfCRT (K76T) of P. falciparum was developed on a LightCycler platform (Roche). The performance characteristics of the real-time assay were compared with those of the nested PCR-restriction fragment-length polymorphism (RFLP) and the sequence analyses of samples obtained from 200 febrile returned travelers, who included 125 infected with P. falciparum (48 of whom were infected CQ-susceptible [K76] and 77 of whom were CQ-resistant [T76] P. falciparum), 22 infected with Plasmodium vivax, 10 infected with Plasmodium ovale, 3 infected with Plasmodium malariae malaria, and 40 infected with other febrile syndromes. All patient samples were coded, and all analyses were performed blindly. The real-time PCR assay detected multiple pfcrt haplotypes associated with CQ resistance in geographically diverse malaria isolates acquired by travelers. Compared with nested-PCR RFLP (the reference standard), the real-time assay was 100% sensitive and 96.2% specific for detection of the P. falciparum K76T mutation. This assay is rapid, sensitive, and specific for the detection and characterization of CQ-resistant P. falciparum malaria in returned travelers. This assay is automated, standardized, and suitable for routine use in clinical diagnostic laboratories.

Factors that are associated with the risk of acquiring Plasmodium knowlesi malaria in Sabah, Malaysia: a case-control study protocol

PubMed Central

Grigg, M J; William, T; Drakeley, C J; Jelip, J; von Seidlein, L; Barber, B E; Fornace, K M; Anstey, N M; Yeo, T W; Cox, J

2014-01-01

Introduction Plasmodium knowlesi has long been present in Malaysia, and is now an emerging cause of zoonotic human malaria. Cases have been confirmed throughout South-East Asia where the ranges of its natural macaque hosts and Anopheles leucosphyrus group vectors overlap. The majority of cases are from Eastern Malaysia, with increasing total public health notifications despite a concurrent reduction in Plasmodium falciparum and P. vivax malaria. The public health implications are concerning given P. knowlesi has the highest risk of severe and fatal disease of all Plasmodium spp in Malaysia. Current patterns of risk and disease vary based on vector type and competence, with individual exposure risks related to forest and forest-edge activities still poorly defined. Clustering of cases has not yet been systematically evaluated despite reports of peri-domestic transmission and known vector competence for human-to-human transmission. Methods and analysis A population-based case–control study will be conducted over a 2-year period at two adjacent districts in north-west Sabah, Malaysia. Confirmed malaria cases presenting to the district hospital sites meeting relevant inclusion criteria will be requested to enrol. Three community controls matched to the same village as the case will be selected randomly. Study procedures will include blood sampling and administration of household and individual questionnaires to evaluate potential exposure risks associated with acquisition of P. knowlesi malaria. Secondary outcomes will include differences in exposure variables between P. knowlesi and other Plasmodium spp, risk of severe P. knowlesi malaria, and evaluation of P. knowlesi case clustering. Primary analysis will be per protocol, with adjusted ORs for exposure risks between cases and controls calculated using conditional multiple logistic regression models. Ethics This study has been approved by the human research ethics committees of Malaysia, the Menzies School of Health Research, Australia, and the London School of Hygiene and Tropical Medicine, UK. PMID:25149186

Pilot survey of expressed sequence tags (ESTs) from the asexual blood stages of Plasmodium vivax in human patients.

PubMed

Merino, Emilio F; Fernandez-Becerra, Carmen; Madeira, Alda M B N; Machado, Ariane L; Durham, Alan; Gruber, Arthur; Hall, Neil; del Portillo, Hernando A

2003-07-21

Plasmodium vivax is the most widely distributed human malaria, responsible for 70-80 million clinical cases each year and large socio-economical burdens for countries such as Brazil where it is the most prevalent species. Unfortunately, due to the impossibility of growing this parasite in continuous in vitro culture, research on P. vivax remains largely neglected. A pilot survey of expressed sequence tags (ESTs) from the asexual blood stages of P. vivax was performed. To do so, 1,184 clones from a cDNA library constructed with parasites obtained from 10 different human patients in the Brazilian Amazon were sequenced. Sequences were automatedly processed to remove contaminants and low quality reads. A total of 806 sequences with an average length of 586 bp met such criteria and their clustering revealed 666 distinct events. The consensus sequence of each cluster and the unique sequences of the singlets were used in similarity searches against different databases that included P. vivax, Plasmodium falciparum, Plasmodium yoelii, Plasmodium knowlesi, Apicomplexa and the GenBank non-redundant database. An E-value of <10(-30) was used to define a significant database match. ESTs were manually assigned a gene ontology (GO) terminology A total of 769 ESTs could be assigned a putative identity based upon sequence similarity to known proteins in GenBank. Moreover, 292 ESTs were annotated and a GO terminology was assigned to 164 of them. These are the first ESTs reported for P. vivax and, as such, they represent a valuable resource to assist in the annotation of the P. vivax genome currently being sequenced. Moreover, since the GC-content of the P. vivax genome is strikingly different from that of P. falciparum, these ESTs will help in the validation of gene predictions for P. vivax and to create a gene index of this malaria parasite.

Evaluation of the ex vivo antimalarial activity of organotin (IV) ethylphenyldithiocarbamate on erythrocytes infected with Plasmodium berghei NK 65.

PubMed

Awang, Normah; Jumat, Hafizah; Ishak, Shafariatul Akmar; Kamaludin, Nurul Farahana

2014-06-01

Malaria is the most destructive and dangerous parasitic disease. The commonness of this disease is getting worse mainly due to the increasing resistance of Plasmodium falciparum against antimalarial drugs. Therefore, the search for new antimalarial drug is urgently needed. This study was carried out to evaluate the effects of dibutyltin (IV) ethylphenyldithiocarbamate (DBEP), diphenyltin (IV) ethylphenyldithiocarbamate (DPEP) and triphenyltin (IV) ethylphenyldithiocarbamate (TPEP) compounds as antimalarial agents. These compounds were evaluated against erythrocytes infected with Plasmodium berghei NK65 via ex vivo. Organotin (IV) ethylphenyldithiocarbamate, [R(n)Sn(C9H10NS2)(4-n)] with R = C4H9 and C6H5 for n = 2; R = C6H5 for n = 3 is chemically synthesised for its potential activities. pLDH assay was employed for determination of the concentration that inhibited 50% of the Plasmodium's activity (IC50) after 24 h treatment at concentration range of 10-0.0000001 mg mL(-1). Plasmodium berghei NK65 was cultured in vitro to determine the different morphology of trophozoite and schizont. Only DPEP and TPEP compounds have antimalarial activity towards P. berghei NK65 at IC50 0.094±0.011 and 0.892±0.088 mg mL(-1), respectively. The IC50 of DPEP and TPEP were lowest at 30% parasitemia with IC50 0.001±0.00009 and 0.0009±0.0001 mg mL(-1), respectively. In vitro culture showed that TPEP was effective towards P. berghei NK65 in trophozoite and schizont morphology with IC50 0.0001±0.00005 and 0.00009±0.00003 μg mL(-1), respectively. In conclusion, DPEP and TPEP have antimalarial effect on erythrocytes infected with P. berghei NK65 and have potential as antimalarial and schizonticidal agents.

Visualisation and quantitative analysis of the rodent malaria liver stage by real time imaging.

PubMed

Ploemen, Ivo H J; Prudêncio, Miguel; Douradinha, Bruno G; Ramesar, Jai; Fonager, Jannik; van Gemert, Geert-Jan; Luty, Adrian J F; Hermsen, Cornelus C; Sauerwein, Robert W; Baptista, Fernanda G; Mota, Maria M; Waters, Andrew P; Que, Ivo; Lowik, Clemens W G M; Khan, Shahid M; Janse, Chris J; Franke-Fayard, Blandine M D

2009-11-18

The quantitative analysis of Plasmodium development in the liver in laboratory animals in cultured cells is hampered by low parasite infection rates and the complicated methods required to monitor intracellular development. As a consequence, this important phase of the parasite's life cycle has been poorly studied compared to blood stages, for example in screening anti-malarial drugs. Here we report the use of a transgenic P. berghei parasite, PbGFP-Luc(con), expressing the bioluminescent reporter protein luciferase to visualize and quantify parasite development in liver cells both in culture and in live mice using real-time luminescence imaging. The reporter-parasite based quantification in cultured hepatocytes by real-time imaging or using a microplate reader correlates very well with established quantitative RT-PCR methods. For the first time the liver stage of Plasmodium is visualized in whole bodies of live mice and we were able to discriminate as few as 1-5 infected hepatocytes per liver in mice using 2D-imaging and to identify individual infected hepatocytes by 3D-imaging. The analysis of liver infections by whole body imaging shows a good correlation with quantitative RT-PCR analysis of extracted livers. The luminescence-based analysis of the effects of various drugs on in vitro hepatocyte infection shows that this method can effectively be used for in vitro screening of compounds targeting Plasmodium liver stages. Furthermore, by analysing the effect of primaquine and tafenoquine in vivo we demonstrate the applicability of real time imaging to assess parasite drug sensitivity in the liver. The simplicity and speed of quantitative analysis of liver-stage development by real-time imaging compared to the PCR methodologies, as well as the possibility to analyse liver development in live mice without surgery, opens up new possibilities for research on Plasmodium liver infections and for validating the effect of drugs and vaccines on the liver stage of Plasmodium.

Visualisation and Quantitative Analysis of the Rodent Malaria Liver Stage by Real Time Imaging

PubMed Central

Douradinha, Bruno G.; Ramesar, Jai; Fonager, Jannik; van Gemert, Geert-Jan; Luty, Adrian J. F.; Hermsen, Cornelus C.; Sauerwein, Robert W.; Baptista, Fernanda G.; Mota, Maria M.; Waters, Andrew P.; Que, Ivo; Lowik, Clemens W. G. M.; Khan, Shahid M.; Janse, Chris J.; Franke-Fayard, Blandine M. D.

2009-01-01

The quantitative analysis of Plasmodium development in the liver in laboratory animals in cultured cells is hampered by low parasite infection rates and the complicated methods required to monitor intracellular development. As a consequence, this important phase of the parasite's life cycle has been poorly studied compared to blood stages, for example in screening anti-malarial drugs. Here we report the use of a transgenic P. berghei parasite, PbGFP-Luccon, expressing the bioluminescent reporter protein luciferase to visualize and quantify parasite development in liver cells both in culture and in live mice using real-time luminescence imaging. The reporter-parasite based quantification in cultured hepatocytes by real-time imaging or using a microplate reader correlates very well with established quantitative RT-PCR methods. For the first time the liver stage of Plasmodium is visualized in whole bodies of live mice and we were able to discriminate as few as 1–5 infected hepatocytes per liver in mice using 2D-imaging and to identify individual infected hepatocytes by 3D-imaging. The analysis of liver infections by whole body imaging shows a good correlation with quantitative RT-PCR analysis of extracted livers. The luminescence-based analysis of the effects of various drugs on in vitro hepatocyte infection shows that this method can effectively be used for in vitro screening of compounds targeting Plasmodium liver stages. Furthermore, by analysing the effect of primaquine and tafenoquine in vivo we demonstrate the applicability of real time imaging to assess parasite drug sensitivity in the liver. The simplicity and speed of quantitative analysis of liver-stage development by real-time imaging compared to the PCR methodologies, as well as the possibility to analyse liver development in live mice without surgery, opens up new possibilities for research on Plasmodium liver infections and for validating the effect of drugs and vaccines on the liver stage of Plasmodium. PMID:19924309

[Plasmodium malariae malaria with more than a 4-month incubation period: difficult to distinguish from a relapse of Plasmodium vivax malaria].

PubMed

Hase, Ryota; Uwamino, Yoshifumi; Muranaka, Kiyoharu; Tochitani, Kentaro; Sogi, Misa; Kitazono, Hidetaka; Hosokawa, Naoto

2013-07-01

We report herein on a case of Plasmodium malariae malaria with more than a 4-month incubation period. A 35-year-old Japanese man who first presented to our clinic with fever and history of travel to Papua New Guinea was suspected of having Plasmodium vivax malaria based on peripheral smear results. We admitted him and initiated treatment with mefloquine. After two days of therapy, he became afebrile. We discharged him, and P. vivax was later confirmed with PCR. We started mefloquine prophylaxis for a planned trip to Papua New Guinea. After his return, a standard dose of primaquine (15 mg x 14 days) was prescribed for a radical cure of P. vivax. About 4 months after his last visit to Papua New Guinea, he returned to our clinic with fever. We suspected a relapse of P. vivax malaria and admitted him for a second time. After two days of mefloquine therapy, his symptoms improved. We discharged him and restarted a higher dose of primaquine (30 mg x 14 days) therapy for a radical cure of P. vivax. Subsequently, the PCR test revealed the parasite was P. malariae and not P. vivax. Only 13 cases of Plasmodium malariae malaria have been reported in Japan during the past 10 years. Blood-stage schizonticides such as mefloquine is not active against the liver stage. Therefore, the use of these drugs for prophylaxis will not be effective for prevention of malaria if its liver stage is longer than the duration of effective chemoprophylaxis. Although the incubation period of P. malariae is typically 13 to 28 days, it occasionally lasts for months or even years. Careful attention should be given to the possibility that P. malariae occasionally has a long incubation period even in the absence of the hypnozoite stage.

Effect of L-arginine on the growth of Plasmodium falciparum and immune modulation of host cells.

PubMed

Awasthi, Vikky; Chauhan, Rubika; Chattopadhyay, Debprasad; Das, Jyoti

2017-01-01

Malaria is a life-threatening disease caused by Plasmodium parasites. The life-cycle of Plasmodium species involves several stages both in mosquito and the vertebrate host. In the erythrocytic stage, Plasmodium resides inside the red blood cells (RBCs), where it meets most of its nutritional requirement by degrad- ing host's haemoglobin. L-arginine is required for growth and division of cells. The present study was aimed to demonstrate the effect of supplementation of different concentrations of L-arginine and L-citrulline on the growth of parasite, and effect of the culture supernatant on the host's peripheral blood mononuclear cells (PBMCs). To examine the effect of supplementation of L-arginine and L-citrulline, Plasmodium falciparum (3D7 strain) was cultured in RPMI 1640, L-arginine deficient RPMI 1640, and in different concentrations of L-arginine, and L-citrulline supplemented in arginine deficient RPMI 1640 medium. To have a holistic view of in vivo cell activation, the PBMCs isolated from healthy human host were cultured in the supernatant collected from P. falciparum culture. Growth of the parasite was greatly enhanced in L-arginine supplemented media and was found to be concentration dependent. However, parasite growth was compromised in L-citrulline supplemented and L-arginine deficient media. The supernatant collected from L-arginine supplemented parasite media (sArg) showed increased FOXP3 and interleukin-10 (IL-10) expression as compared to the supernatant collected from L-citrulline supple- mented parasite media (sCit). The in vitro culture results showed, decreased parasite growth, and decreased expression of programmed cell death-1 (PD-1) (a coinhibitory molecule) and IL-10 in the L-citrulline supplemented media as compared to L-arginine supplemented media. Hence, it was concluded that L-citrulline supplementation would be a better alternative than L-arginine to inhibit the parasite growth.

Histone deacetylases play a major role in the transcriptional regulation of the Plasmodium falciparum life cycle.

PubMed

Chaal, Balbir K; Gupta, Archna P; Wastuwidyaningtyas, Brigitta D; Luah, Yen-Hoon; Bozdech, Zbynek

2010-01-22

The apparent paucity of molecular factors of transcriptional control in the genomes of Plasmodium parasites raises many questions about the mechanisms of life cycle regulation in these malaria parasites. Epigenetic regulation has been suggested to play a major role in the stage specific gene expression during the Plasmodium life cycle. To address some of these questions, we analyzed global transcriptional responses of Plasmodium falciparum to a potent inhibitor of histone deacetylase activities (HDAC). The inhibitor apicidin induced profound transcriptional changes in multiple stages of the P. falciparum intraerythrocytic developmental cycle (IDC) that were characterized by rapid activation and repression of a large percentage of the genome. A major component of this response was induction of genes that are otherwise suppressed during that particular stage of the IDC or specific for the exo-erythrocytic stages. In the schizont stage, apicidin induced hyperacetylation of histone lysine residues H3K9, H4K8 and the tetra-acetyl H4 (H4Ac4) and demethylation of H3K4me3. Interestingly, we observed overlapping patterns of chromosomal distributions between H4K8Ac and H3K4me3 and between H3K9Ac and H4Ac4. There was a significant but partial association between the apicidin-induced gene expression and histone modifications, which included a number of stage specific transcription factors. Taken together, inhibition of HDAC activities leads to dramatic de-regulation of the IDC transcriptional cascade, which is a result of both disruption of histone modifications and up-regulation of stage specific transcription factors. These findings suggest an important role of histone modification and chromatin remodeling in transcriptional regulation of the Plasmodium life cycle. This also emphasizes the potential of P. falciparum HDACs as drug targets for malaria chemotherapy.

Correlation of Survival Rates of Anopheles dirus A (Diptera: Culicidae) with Different Infection Densities of Plasmodium cynomolgi

DTIC Science & Technology

1986-01-01

rhesus, le premier indemne, le second infeste par Plasmodium cynomolgi. Vingt moustiques gorges de sang constituaient le groupe temoin non infest& et...60 autres moustiques infest& ont ete divises en trois groupes de 20 moustiques (groupes infest& 1, 2 et 3). On a evaI& le nombre moyen d’oocystes...port& par les moustiques en dissequant ceux du groupe 1 au septieme jour de I’etude; on a recherche la presence de sporozo’ites dans les glandes

Partial purification and characterization of DNA topoisomerase II from Plasmodium falciparum.

PubMed

Chavalitshewinkoon, P; Leelaphiwat, S; Wilairat, P

1994-03-01

DNA topoisomerase II from Plasmodium falciparum was partially purified by FPLC using three columns: Econo-Pac Q, heparin-agarose and Mono Q. The enzyme showed ATP- and Mg2 +/- dependent activities in a decatenation assay, with optimum concentrations of 0.5 and 10 mM, respectively. Furthermore, highest activity was detected in the presence of 100 mM KCI. Enzyme decatenation activity was not inhibited by the DNA topoisomerase I inhibitor, camptothecin, but was sensitive to both prokaryotic and eukaryotic DNA topoisomerase II inhibitors.

Differential Susceptibilities of Anopheles albimanus and Anopheles pseudopunctipennis to Infections with Coindigenous Plasmodium vivax Variants VK210 and VK247 in Southern Mexico

PubMed Central

Gonzalez-Ceron, Lilia; Rodriguez, Mario H.; Nettel, Jose C.; Villarreal, Cuauhtemoc; Kain, Kevin C.; Hernandez, Juan E.

1999-01-01

The susceptibilities to coindigenous Plasmodium vivax of colonized Anopheles albimanus and Anopheles pseudopunctipennis from southern Mexico were investigated by simultaneous feeding with infected blood obtained from patients. The genes encoding circumsporozoite protein variant types (VK210 and VK247) in blood samples were determined by PCR and oligonucleotide probe hybridization. A. albimanus was more susceptible to VK210, and A. pseudopunctipennis was more susceptible to VK247. PMID:9864243

Differential susceptibilities of Anopheles albimanus and Anopheles pseudopunctipennis to infections with coindigenous Plasmodium vivax variants VK210 and VK247 in southern Mexico.

PubMed

Gonzalez-Ceron, L; Rodriguez, M H; Nettel, J C; Villarreal, C; Kain, K C; Hernandez, J E

1999-01-01

The susceptibilities to coindigenous Plasmodium vivax of colonized Anopheles albimanus and Anopheles pseudopunctipennis from southern Mexico were investigated by simultaneous feeding with infected blood obtained from patients. The genes encoding circumsporozoite protein variant types (VK210 and VK247) in blood samples were determined by PCR and oligonucleotide probe hybridization. A. albimanus was more susceptible to VK210, and A. pseudopunctipennis was more susceptible to VK247.

A simple field kit for the determination of drug susceptibility in Plasmodium falciparum.

PubMed

Nguyen-Dinh, P; Magloire, R; Chin, W

1983-05-01

A field kit has been developed which greatly simplifies the performance of the 48-hour in vitro test for drug resistance in Plasmodium falciparum. The kit uses an easily reconstituted lyophilized culture medium, and requires only a fingerprick blood sample. In parallel tests with 13 isolates of P. falciparum in Haiti, the new technique had a success rate equal to that of the previously described method, with comparable results in terms of parasite susceptibility in vitro to chloroquine and pyrimethamine.