Response of sweet sorghum lines to stalk pathogens Fusarium thapsinum and Macrophomina phaseolina

USDA-ARS?s Scientific Manuscript database

Sweet sorghum (Sorghum bicolor (L.) Moench) has potential for bioenergy. It is adapted to a variety of U.S. locations and the extracted juice can be directly fermented into ethanol. However, little research on fungal stalk rots, diseases that pose serious constraints for yield and quality of juice a...

[Biochemical basis of tolerance to osmotic stress in phytopathogenic fungus: The case of Macrophomina phaseolina (Tassi) Goid.

PubMed

Martínez-Villarreal, Rodolfo; Garza-Romero, Tamar S; Moreno-Medina, Víctor R; Hernández-Delgado, Sanjuana; Mayek-Pérez, Netzahualcoyotl

Fungus Macrophomina phaseolina (Tassi) Goid. is the causative agent of charcoal rot disease which causes significant yield losses in major crops such as maize, sorghum, soybean and common beans in Mexico. This fungus is a facultative parasite which shows broad ability to adapt itself to stressed environments where water deficits and/or high temperature stresses commonly occur. These environmental conditions are common for most cultivable lands throughout Mexico. Here we describe some basic facts related to the etiology and epidemiology of the fungus as well as to the importance of responses to stressed environments, particularly to water deficits, based on morphology and growth traits, as well as on physiology, biochemistry and pathogenicity of fungus M. phaseolina. To conclude, we show some perspectives related to future research into the genus, which emphasize the increasing need to improve the knowledge based on the application of both traditional and biotechnological tools in order to elucidate the mechanisms of resistance to environmental stress which can be extrapolated to other useful organisms to man. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Xyloglucan endotransglycosylase/hydrolase genes from a susceptible and resistant jute species show opposite expression pattern following Macrophomina phaseolina infection

PubMed Central

Sharmin, Sazia; Azam, Muhammad Shafiul; Islam, Md. Shahidul; Sajib, Abu Ashfaqur; Mahmood, Niaz; Hasan, A. M. Mahedi; Ahmed, Razib; Sultana, Kishwar; Khan, Haseena

2012-01-01

Two of the most widely and intensively cultivated jute species, Corchorus capsularis and Corchorus olitorius, suffer severely from a stem rot disease caused by the fungus Macrophomina phaseolina. Wild jute species, C. trilocularis, shows resistance to this pathogenic fungus. In this study, the technique of differential display was applied to identify genes which are differentially expressed, under both infected and un-infected conditions, between C. trilocularis and C. olitorius var O-72. Two xyloglucan endotransglycosylase/hydrolase (XTH) genes designated CoXTH1 (from Corchorus olitorius) and CtXTH1 (from C.trilocularis) were identified from each of the two species which show different expression patterns upon fungal infection. A steady rise in the expression of CtXTH1 in response to infection was observed by quantitative real time PCR whereas the expression of CoXTH1 was found to be downregulated. Full length sequences of these two genes were determined using primer based gene walking and RACE PCR. This study confirms the involvement of XTH in molecular interactions between M. phaseolina and jute. However, it remains to be explored whether XTH is an essential component of the signaling pathway involved in plant-fungal interaction. PMID:23336031

Xyloglucan endotransglycosylase/hydrolase genes from a susceptible and resistant jute species show opposite expression pattern following Macrophomina phaseolina infection.

PubMed

Sharmin, Sazia; Azam, Muhammad Shafiul; Islam, Md Shahidul; Sajib, Abu Ashfaqur; Mahmood, Niaz; Hasan, A M Mahedi; Ahmed, Razib; Sultana, Kishwar; Khan, Haseena

2012-11-01

Two of the most widely and intensively cultivated jute species, Corchorus capsularis and Corchorus olitorius, suffer severely from a stem rot disease caused by the fungus Macrophomina phaseolina. Wild jute species, C. trilocularis, shows resistance to this pathogenic fungus. In this study, the technique of differential display was applied to identify genes which are differentially expressed, under both infected and un-infected conditions, between C. trilocularis and C. olitorius var O-72. Two xyloglucan endotransglycosylase/hydrolase (XTH) genes designated CoXTH1 (from Corchorus olitorius) and CtXTH1 (from C.trilocularis) were identified from each of the two species which show different expression patterns upon fungal infection. A steady rise in the expression of CtXTH1 in response to infection was observed by quantitative real time PCR whereas the expression of CoXTH1 was found to be downregulated. Full length sequences of these two genes were determined using primer based gene walking and RACE PCR. This study confirms the involvement of XTH in molecular interactions between M. phaseolina and jute. However, it remains to be explored whether XTH is an essential component of the signaling pathway involved in plant-fungal interaction.

Interactions of Heterodera glycines, Macrophomina phaseolina, and Mycorrhizal Fungi on Soybean in Kansas.

PubMed

Winkler, H E; Hetrick, B A; Todd, T C

1994-12-01

The impact of naturally occurring arbuscular mycorrhizal fungi on soybean growth and their interaction with Heterodera glycines were evaluated in nematode-infested and uninfested fields in Kansas. Ten soybean cultivars from Maturity Groups III-V with differential susceptibility to H. glycines were treated with the fungicide benomyl to suppress colonization by naturally occurring mycorrhizal fungi and compared with untreated control plots. In H. glycines-infested soil, susceptible cultivars exhibited 39% lower yields, 28% lower colonization by mycorrhizal fungi, and an eightfold increase in colonization by the charcoal rot fungus, Macrophomina phaseolina, compared with resistant cultivars. In the absence of the nematode, susceptible cultivars exhibited 10% lower yields than resistant cultivars, root colonization of resistant vs. susceptible soybean by mycorrhizal fungi varied with sampling date, and there were no differences in colonization by M. phaseolina between resistant and susceptible cultivars. Benomyl application resulted in 19% greater root growth and 9% higher seed yields in H. glycines-infested soil, but did not affect soybean growth and yield in the absence of the nematode. Colonization of soybean roots by mycorrhizal fungi was negatively correlated with H. glycines population densities due to nematode antagonism to the mycorrhizal fungi rather than suppression of nematode populations. Soybean yields were a function of the pathogenic effects of H. glycines and M. phaseolina, and, to a lesser degree, the stimulatory effects of mycorrhizal fungi.

[Morphological and molecular characterization of isolates of Macrophomina phaseolina associated with sugarcane in Mexico].

PubMed

Leyva-Mir, Santos G; Velázquez-Martínez, Guadalupe C; Tlapal-Bolaños, Bertha; Tovar-Pedraza, Juan M; Rosas-Saito, Greta H; Alvarado-Gómez, Omar G

2015-01-01

Charcoal rot caused by Macrophomina phaseolina is an important disease of sugarcane in Mexico. This study was carried out to characterize isolates of M. phaseolina obtained from sugarcane by the combination of morphological and molecular analyses. The morphological characterization of 10 isolates was performed using scanning electron microscopy and light microscopy. To confirm the morphological identification, rDNA from two representative isolates was extracted, and the internal transcribed spacer (ITS) region was amplified by polymerase chain reaction and sequenced using specific primers MpKF1 and MpKR1. Based on their morphological characteristics, all isolates were identified as M. phaseolina. Moreover, the analysis of two ITS sequences showed 100% similarity with the M. phaseolina sequences deposited in the GenBank. To our knowledge, this is the first study in the world aimed at characterizing isolates of M. phaseolina obtained from sugarcane. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Antifungal activity of various essential oils against Rhizoctonia solani and Macrophomina phaseolina as major bean pathogens.

PubMed

Khaledi, N; Taheri, P; Tarighi, S

2015-03-01

The main objective of this study was to investigate the effect of various essential oils (EOs) to decrease the activity of cell wall degrading enzymes (CWDEs) produced by fungal phytopathogens, which are associated with disease progress. Also, effect of seed treatment and foliar application of peppermint EO and its main constituent, menthol, on diseases caused by two necrotrophic pathogens on bean was investigated. Antifungal activity of EOs on Rhizoctonia solani and Macrophomina phaseolina, as bean pathogens, was evaluated. The EOs of Mentha piperita, Bunium persicum and Thymus vulgaris revealed the highest antifungal activity against fungi. The EO of M. piperita had the lowest minimum inhibitory concentration (MIC) for R. solani among the three EOs tested. This pathogen did not grow in the presence of M. piperita, B. persicum and T. vulgaris EOs at 850, 1200 and 1100 ppm concentrations, respectively. The B. persicum EO had the lowest MIC for M. phaseolina as this fungus did not grow in the presence of M. piperita, B. persicum and T. vulgaris EOs at concentrations of 975, 950 and 1150 ppm, respectively. Hyphae exposed to EOs showed structural changes. Activities of cellulase and pectinase, as main CWDEs of pathogens, decreased by EOs at low concentration without effect on fungal growth. Seed treatment and foliar application of peppermint EO and/or menthol significantly reduced the development of bean diseases caused by both fungi. Higher capability of menthol than peppermint EO in decreasing diseases on bean was observed. Reducing CDWEs activity is a mechanism of EOs' effect on fungi. Higher antifungal activity of menthol compared to peppermint EO was observed not only in vitro but also in vivo. Effect of EOs on CWDEs involved in pathogenesis is described in this study for the first time. Menthol can be used as a botanical fungicide to control destructive fungal diseases on bean. © 2014 The Society for Applied Microbiology.

Diallel crosses for resistance to Macrophomina phaseolina and Thanatephorus cucumeris on cowpea.

PubMed

Lima, L R L; Damasceno-Silva, K J; Noronha, M A; Schurt, D A; Rocha, M M

2017-09-27

This study aimed at identifying and selecting through partial diallel analysis, segregating populations of cowpea resistant to Macrophomina phaseolina and Thanatephorus cucumeris, based on the evaluation of general (GCA) and specific combining ability (SCA), involved in the genetic control of resistance. For this reason, 19 grouped cowpea genotypes, considering the resistance to these pathogens, were crossed in partial diallel scheme 14 x 5, during 2013 and 2014. The 70 F 2 populations and the 19 parents were evaluated in a greenhouse as the reaction to pathogens, separately. The diallel analysis was performed according to the model of partial diallel proposed by Geraldi and Miranda Filho (1988). The additive effects predominated in the genetic control of the traits severity of charcoal rot (SEV) and area under the disease progress curve (AUDPC) to web blight, enabling the achievement of genetic gain with selection of resistant strains. Analyzing the effects of GCA, the parents BR 14-Mulato, BRS Tumucumaque and BRS Guariba, have a higher concentration of favorable alleles, highlighting, according to the values of SCA, the combinations BR 14-Mulato x MNC02-675F-4-10, BRS Tumucumaque x IT98K-1092-1, BRS Tumucumaque x MNC02-675F-4-10, BRS Tumucumaque x MNC02-675F-9-2, BRS Guariba x IT98K-1092-1, BRS Guariba x MNC02-675F-4-9, and BRS Guariba x MNC02-675F-4-10, as the most promising and indicated to obtain lines resistant to M. phaseolina and T. cucumeris in cowpea, simultaneously.

Ectopic Expression of JcWRKY Confers Enhanced Resistance in Transgenic Tobacco Against Macrophomina phaseolina.

PubMed

Agarwal, Parinita; Patel, Khantika; Agarwal, Pradeep K

2018-04-01

Plants possess an innate immune system comprising of a complex network of closely regulated defense responses involving differential gene expression mediated by transcription factors (TFs). The WRKYs comprise of an important plant-specific TF family, which is involved in regulation of biotic and abiotic defenses. The overexpression of JcWRKY resulted in improved resistance in transgenic tobacco against Macrophomina phaseolina. The production of reactive oxygen species (ROS) and its detoxification through antioxidative system in the transgenics facilitates defense against Macrophomina. The enhanced catalase activity on Macrophomina infection limits the spread of infection. The transcript expression of antioxidative enzymes gene (CAT and SOD) and salicylic acid (SA) biosynthetic gene ICS1 showed upregulation during Macrophomina infection and combinatorial stress. The enhanced transcript of pathogenesis-related genes PR-1 indicates the accumulation of SA during different stresses. The PR-2 and PR-5 highlight the activation of defense responses comprising of activation of hydrolytic cleavage of glucanases and thaumatin-like proteins causing disruption of fungal cells. The ROS homeostasis in coordination with signaling molecules regulate the defense responses and inhibit fungal growth.

Evidence for host preference of Macrophomina phaseolina on strawberry

USDA-ARS?s Scientific Manuscript database

With the transition from broadcast preplant fumigation to individual bed treatment using alternative fumigants, M. phaseolina has become an emerging disease problem in California strawberry production, causing serious losses in all production districts. Population analysis using SSR markers of 68 i...

Biotransformation of perfumery terpenoids, (−)-ambrox® by a fungal culture Macrophomina phaseolina and a plant cell suspension culture of Peganum harmala

PubMed Central

2012-01-01

Background Biotransformation offers chemo enzymatic system to modify the compounds into their novel analogues which are difficult to synthesize by chemical methods. This paper describes the biotransformational studies of ambrox, one of the most important components of natural Ambergris (wale sperm) with fungal and plant cell culture. Results Biotransformation of (−)-ambrox (1) with a fungal cell culture of Macrophomina phaseolina and a plant cell suspension cultures of Peganum harmala yielded oxygenated products, 3β-hydroxyambrox (2), 6β-hydroxyambrox (3), 1α-hydroxy-3oxoambrox (4), 1α,3β-dihydroxyambrox (5), 13,14,15,16-tetranorlabdane-3-oxo-8,12-diol (6), 3-oxoambrox (7), 2α-hydroxyambrox (8), 3β-hydroxysclareolide (9), and 2α,3β-dihydroxyambrox (10). Metabolite 4 was found to be new compound. These metabolites were structurally characterized on the basis of spectroscopic studies. Conclusion Nine oxygenated metabolites of (−)-ambrox (1) were obtained from Macrophomina phaseolina and Peganum harmala. Enzymatic system of screened organisms introduced hydroxyl and keto functionalities at various positions of compound 1 in a stereo- and regio-controlled manner. PMID:22863186

Antagonistic effects of Bacillus subtilis subsp. subtilis and B. amyloliquefaciens against Macrophomina phaseolina: SEM study of fungal changes and UV-MALDI-TOF MS analysis of their bioactive compounds.

PubMed

Torres, M J; Brandan, C Pérez; Petroselli, G; Erra-Balsells, R; Audisio, M C

2016-01-01

The antifungal effect of Bacillus subtilis subsp. subtilis PGPMori7 and Bacillus amyloliquefaciens PGPBacCA1 was evaluated against Macrophomina phaseolina (Tassi) Goid. Cell suspension (CS), cell-free supernatant (CFS) and the lipopeptide fraction (LF) of PGPMori7 and PGPBacCA1 were screened against three different M. phaseolina strains. CS exhibited the highest inhibitory effect (around 50%) when compared to those of CFS and LF, regardless of the fungal strain studied. The synthesis of lipopeptides was studied by UV-MALDI TOF. Chemical analysis of Bacillus metabolite synthesis revealed that surfactin and iturin were mainly produced in liquid medium. Potential fengycin was also co-produced when both Bacillus were cultivated in solid medium. In co-culture assays, the bacterial colony-fungal mycelium interface at the inhibition zone was evaluated by both scanning electron microscopy (SEM) and UV-MALDI TOF, the former to determine the structural changes on M. phaseolina cells and the latter to identify the main bioactive molecules involved in the inhibitory effect. PGPBacCA1 produced surfactin, iturin and fengycin in the inhibition zone while PGPMori7 only produced these metabolites within its colony and not in the narrow inhibition zone. Interestingly, SEM revealed that PGPBacCA1 induced damage in M. phaseolina sclerotia, generating a fungicidal effect as no growth was observed when normal growth conditions were reestablished. In turn, PGPMori7 inhibited the growth of the Macrophomina mycelium without fungal injury, resulting only in a fungistatic activity. From these results, it was determined that the two bacilli significantly inhibited the growth of an important phytopathogenic fungus by at least two different mechanisms: lipopeptide synthesis and competition among microorganisms. Copyright © 2015 Elsevier GmbH. All rights reserved.

Occurrence of Root Rot and Vascular Wilt Diseases in Roselle (Hibiscus sabdariffa L.) in Upper Egypt.

PubMed

Hassan, Naglaa; Shimizu, Masafumi; Hyakumachi, Mitsuro

2014-03-01

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt.

Isolation and purification of fungal pathogen (Macrophomina phaseolina) induced chitinase from moth beans (Phaseolus aconitifolius)

PubMed Central

Garg, Neelima; Gupta, Himanshu

2010-01-01

Objective: Chitinase (EC 3.2.1.14) is one of the major pathogenesis-related proteins, which is a polypeptide that accumulates extracellularly in infected plant tissue. An attempt was made to isolate and purify the chitanase enzyme using moth beans as an enzyme source. Materials and Method: The enzyme was isolated and purified from moth beans against the fungal pathogen Macrophomina phaseolina strain 2165. The isolation and purification was done in both in vitro and in vivo conditions. Purification of chitinase was carried out to obtain three fractions, viz. 50°C heated, ammonium sulfate precipitated and sephadex G-25 column-eluted fractions. The molecular mass of Chitinase was directly estimated by sodium dodecyl sulfate-polyacryamide gel electroresis (SDS-PAGE). Result: The yield is sufficient for initial characterization studies of the enzyme. The molecular study of the enzyme shows the possibility of generating the defense mechanism in plants in which it cannot occur. Chitinase was purified by gel filtration chromatography with 20.75-fold and 32.78-fold purification in the in vitro and in vivo conditions, respectively. The enzyme shows a maximum activity after 90 min with 0.1 ml of colloidal chitin as a substrate and 0.4 ml of crude chitinase extract. The optimum pH of 5.0 and an optimum temperature of 40°C was found for maximal activity. The molecular weight of purified chitinase was estimated to be 30 kDa by SDS-PAGE. Conclusion: The chitinase isolated in both in vitro and in vivo conditions is stable andactive. PMID:21814429

New insights in Trichoderma harzianum antagonism of fungal plant pathogens by secreted protein analysis.

PubMed

Monteiro, Valdirene Neves; do Nascimento Silva, Roberto; Steindorff, Andrei Stecca; Costa, Fabio Teles; Noronha, Eliane Ferreira; Ricart, Carlos André Ornelas; de Sousa, Marcelo Valle; Vainstein, Marilene Henning; Ulhoa, Cirano José

2010-10-01

Trichoderma harzianum ALL42 were capable of overgrowing and degrading Rhizoctonia solani and Macrophomina phaseolina mycelia, coiling around the hyphae with formation of apressoria and hook-like structures. Hyphae of T. harzianum ALL42 did not show any coiling around Fusarium sp. hyphae suggesting that mycoparasitism may be different among the plant pathogens. In this study, a secretome analysis was used to identify some extracellular proteins secreted by T. harzianum ALL42 after growth on cell wall of M. phaseolina, Fusarium sp., and R. solani. The secreted proteins were analyzed by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. A total of 60 T. harzianum ALL42 secreted proteins excised from the gel were analyzed from the three growth conditions. While seven cell wall-induced proteins were identified, more than 53 proteins spots remain unidentified, indicating that these proteins are either novel proteins or proteins that have not yet been sequenced. Endochitinase, β-glucosidase, α-mannosidase, acid phosphatase, α-1,3-glucanase, and proteases were identified in the gel and also detected in the supernatant of culture.

Occurrence of Root Rot and Vascular Wilt Diseases in Roselle (Hibiscus sabdariffa L.) in Upper Egypt

PubMed Central

Hassan, Naglaa; Shimizu, Masafumi

2014-01-01

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt. PMID:24808737

Practical use of CMC-amended rhizobial inoculant for Mucuna pruriens cultivation to enhance the growth and protection against Macrophomina phaseolina.

PubMed

Aeron, Abhinav; Khare, Ekta; Kumar Arora, Naveen; Kumar Maheshwari, Dinesh

2012-01-01

In many parts of the world Mucuna pruriens is used as an important medicinal, forage and green manure crop. In the present investigation the effect of the addition of CMC in carrier during development of bioformulation on shelflife, plant growth promotive and biocontrol activity against Macrophomina phaseolina was screened taking M. pruriens as a test crop. Ensifer meliloti RMP6(Ery+Kan+) and Bradyrhizobium sp. BMP7(Tet+Kan+) (kanamycin resistance engineered by Tn5 transposon mutagenesis) used in the study showed production of siderophore, IAA, solubilizing phosphate and biocontrol of M. phaseolina. RMP6(Ery+Kan+) also showed ACC deaminase activity. The survival of both the strains in sawdust-based bioformulation was enhanced with an increase in the concentration of CMC from 0 to 1%. At 0% CMC Bradyrhizobium sp. BMP7(Tet+Kan+) showed more increase in nodule number/plant (500.00%) than E. meliloti RMP6(Ery+Kan+) (52.38%), over the control in M. phaseolina-infested soil. There was 185.94% and 59.52% enhancement in nodule number/plant by RMP6(Ery+Kan+) and BMP7(Tet+Kan+) with an increase in the concentration of CMC from 0% to 1% in the bioformulations. However further increase in concentration of CMC did not result in enhancement in survival of either the strains or nodule number/plant.

Optimization for rapid synthesis of silver nanoparticles and its effect on phytopathogenic fungi

NASA Astrophysics Data System (ADS)

Krishnaraj, C.; Ramachandran, R.; Mohan, K.; Kalaichelvan, P. T.

In this present study, silver nanoparticles were synthesized by green chemistry approach using Acalypha indica leaf extract as reducing agents. The reaction medium employed in the synthesis process was optimized to attain better yield, controlled size and stability. Further, the biosynthesized silver nanoparticles were conformed through UV-vis spectrum, XRD and HR-TEM analyses. Different concentration of silver nanoparticles were tested to know the inhibitory effect of fungal plant pathogens namely Alternaria alternata, Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea and Curvularia lunata. Interestingly, 15 mg concentration of silver nanoparticles showed excellent inhibitory activity against all the tested pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

A direct observation technique for evaluating sclerotium germination by Macrophomina phaseolina and effects of biocontrol materials on survival of sclerotia in soil.

PubMed

Pratt, Robert G

2006-08-01

Germination of sclerotia of Macrophomina phaseolina was quantified by direct microscopic observation following application of experimental treatments in vitro and incubation of sclerotia in soil. To assay germination, pieces of agar containing sclerotia were macerated in dilute, liquid cornmeal agar on glass slides; thinly spread; and incubated in a saturated atmosphere for 18-22 h. Germinated sclerotia then were identified by morphological features of germ hyphae. Frequencies of germination were similar in three dilute agar media. Germination was not affected by air-drying sclerotia for 2 weeks, but it was significantly reduced after 4 weeks and greatly reduced or eliminated after 6 or 8 weeks. Survival of sclerotia for 14 days in soil was greatest at 50, 75, and 100% moisture-holding capacity, less at 0 and 25%, and least at 125% (flooded soil). Incorporation of ground poultry litter into soil at 5% by weight reduced survival of sclerotia after 13 days, and incorporation of litter at 10% nearly eliminated it. These results indicate that the direct-observation technique may be used to evaluate animal wastes and other agricultural byproducts for biocontrol activity against sclerotia of M. phaseolina in soil.

Advancing our understanding of charcoal rot in soybeans

USDA-ARS?s Scientific Manuscript database

Charcoal rot (Macrophomina phaseolina (Tassi) Goid ) of soybean [Glycine max (L.) Merr.], is an important but commonly misidentified disease, and very few summary articles exist on this pathosystem. Research conducted over the last 10 years has improved our understanding of the environment conducive...

Recovery of Extracellular Lipolytic Enzymes from Macrophomina phaseolina by Foam Fractionation with Air

PubMed Central

Germani, José Carlos

2013-01-01

Macrophomina phaseolina was cultivated in complex and simple media for the production of extracellular lipolytic enzymes. Culture supernatants were batch foam fractionated for the recovery of these enzymes, and column design and operation included the use of P 2 frit (porosity 40 to 100 μm), air as sparging gas at variable flow rates, and Triton X-100 added at the beginning or gradually in aliquots. Samples taken at intervals showed the progress of the kinetic and the efficiency parameters. Best results were obtained with the simple medium supernatant by combining the stepwise addition of small amounts of the surfactant with the variation of the air flow rates along the separation. Inert proteins were foamed out first, and the subsequent foamate was enriched in the enzymes, showing estimated activity recovery (R), enrichment ratio (E), and purification factor (P) of 45%, 34.7, and 2.9, respectively. Lipases were present in the enriched foamate. PMID:23738054

Nanotechnology Enabled Enhancement of Enzyme Activity and Thermostability: Study on Impaired Pectate Lyase from Attenuated Macrophomina phaseolina in Presence of Hydroxyapatite Nanoparticle

PubMed Central

Dutta, Nalok; Mukhopadhyay, Arka; Dasgupta, Anjan Kr.; Chakrabarti, Krishanu

2013-01-01

In this paper we show that hydroxyapatite nanoparticles (NP) can not only act as a chaperon (by imparting thermostability) but can serve as a synthetic enhancer of activity of an isolated extracellular pectate lyase (APL) with low native state activity. The purified enzyme (an attenuated strain of Macrophomina phaseolina) showed feeble activity at 50°C and pH 5.6. However, on addition of 10.5 µg/ml of hydroxyapatite nanoparticles (NP), APL activity increased 27.7 fold with a 51 fold increase in half-life at a temperature of 90°C as compared to untreated APL. The chaperon like activity of NP was evident from entropy–enthalpy compensation profile of APL. The upper critical temperature for such compensation was elevated from 50°C to 90°C in presence of NP. This dual role of NP in enhancing activity and conferring thermostability to a functionally impaired enzyme is reported for the first time. PMID:23691068

Anaerobic soil disinfestation disease control performance in strawberry as influenced by environmental variables

USDA-ARS?s Scientific Manuscript database

Sustainability of the California strawberry industry is challenged by soil-borne diseases caused by Fusarium oxysporum (Fo), Macrophomina phaseolina (Mp) and Verticillium dahliae (Vd). Anaerobic soil disinfestation (ASD) has been studied as a non-fumigant measure for control of these diseases. This ...

Evaluation of common bean (Phaseolus vulgaris) response to charcoal rot

USDA-ARS?s Scientific Manuscript database

Charcoal rot in common beans (Phaseolus vulgaris L.), caused by Macrophomina phaseolina (Tassi) Gold. (Mph), is an endemic disease in the prevailing hot and dry conditions in southern Puerto Rico. This study evaluated the 120 bean genotypes that compose the BASE 120 panel under screenhouse conditio...

Effect of Charcoal Rot on Selected Putative Drought Resistant Soybean Genotypes and Yield.

USDA-ARS?s Scientific Manuscript database

Charcoal rot (CR), caused by the fungus Macrophomina phaseolina (Tassi) Goid. is a pervasive disease of economic significance on soybeans ([(Glycine max (L.) Merr.) that is exacerbated when plants are under stress, especially under heat and drought condition. Thus, the objective of this research was...

Glyceollin is an important component of soybean plant defense against Phytophthora sojae and Macrophomina phaseolina

USDA-ARS?s Scientific Manuscript database

Transgenic soybean plants were generated using bombardment of embryogenic cultures with the PAL5 (phenylalanine ammonia lyase), CHS6 (chalcone synthase) and IFS2 (isoflavone synthase) genes in sense orientation, driven by the cotyledon-preferable lectin promoter, or with the IFS2 (isoflavone synthas...

Screening Brazilian Macrophomina phaseolina isolates for alkaline lipases and other extracellular hydrolases.

PubMed

Schinke, Claudia; Germani, José C

2012-03-01

Macrophomina phaseolina, phylum Ascomycota, is a phytopathogenic fungus distributed worldwide in hot dry areas. There are few studies on its secreted lipases and none on its colony radial growth rate, an indicator of fungal ability to use nutrients for growth, on media other than potato-dextrose agar. In this study, 13 M. phaseolina isolates collected in different Brazilian regions were screened for fast-growth and the production of hydrolases of industrial interest, especially alkaline lipases. Hydrolase detection and growth rate determination were done on citric pectin, gelatin, casein, soluble starch, and olive oil as substrates. Ten isolates were found to be active on all substrates tested. The most commonly detected enzymes were pectinases, amylases, and lipases. The growth rate on pectin was significantly higher (P < 0.05), while the growth rates on the different media identified CMM 2105, CMM 1091, and PEL as the fastest-growing isolates. The lipase activity of four isolates grown on olive oil was followed for 4 days by measuring the activity in the cultivation broth. The specific lipolytic activity of isolate PEL was significantly higher at 96 h (130 mU mg protein(-1)). The broth was active at 37 °C, pH 8, indicating the potential utility of the lipases of this isolate in mild alkaline detergents. There was a strong and positive correlation (0.86) between radial growth rate and specific lipolytic activity.

Host Specialization in the Charcoal Rot Fungus, Macrophomina phaseolina.

PubMed

Su, G; Suh, S O; Schneider, R W; Russin, J S

2001-02-01

ABSTRACT To investigate host specialization in Macrophomina phaseolina, the fungus was isolated from soybean, corn, sorghum, and cotton root tissue and soil from fields cropped continuously to these species for 15 years in St. Joseph, LA. Chlorate phenotype of each isolate was determined after growing on a minimal medium containing 120 mM potassium chlorate. Consistent differences in chlorate sensitivity were detected among isolates from different hosts and from soil versus root. To further explore genetic differentiation among fungal isolates from each host, these isolates were examined by restriction fragment length polymorphism and random amplified polymorphic DNA (RAPD) analysis. No variations were observed among isolates in restriction patterns of DNA fragments amplified by polymerase chain reaction covering the internal transcribed spacer region, 5.8S rRNA and part of 25S rRNA, suggesting that M. phaseolina constitutes a single species. Ten random primers were used to amplify the total DNA of 45 isolates, and banding patterns resulting from RAPD analysis were compared with the neighbor-joining method. Isolates from a given host were genetically similar to each other but distinctly different from those from other hosts. Chlorate-sensitive isolates were distinct from chlorate-resistant isolates within a given host. In greenhouse tests, soybean, sorghum, corn, and cotton were grown separately in soil infested with individual isolates of M. phaseolina that were chosen based on their host of origin and chlorate phenotype. Root colonization and plant weight were measured after harvesting. More colonization of corn roots occurred when corn was grown in soil containing corn isolates compared with isolates from other hosts. However, there was no host specialization in isolates from soybean, sorghum, or cotton. More root colonization in soybean occurred with chlorate-sensitive than with chlorate-resistant isolates.

Greenhouse evaluation of commercial soybean cultivars adapted to the northern United States for resistance to charcoal rot

USDA-ARS?s Scientific Manuscript database

Thirty (30) and sixty-seven (67) commercially available soybean (Glycine max (L.) Merr) cultivars from Wisconsin (Maturity group (MG) I-II) and Indiana (MG II-III), respectively, were evaluated for charcoal rot (CR; Macrophomina phaseolina (Tassi) Goid) resistance using a cut-stem greenhouse assay. ...

Effect of anaerobic soil disinfestation and mustard seed meal for control of charcoal rot in California strawberries

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD) and mustard seed meal (MSM) appear to be promising non-fumigant alternatives for soilborne disease control. However studies of their effect on charcoal rot caused by Macrophomina phaseolina in California strawberry are limited. ASD with rice bran 20 t ha-1 (ASD-RB...

Evaluation of soybean genotypes for resistance to charcoal rot

USDA-ARS?s Scientific Manuscript database

Charcoal rot caused by Macrophomina phaseolina causes more yield loss in soybean than most other diseases in the southern U.S.A. There are no commercial genotypes marketed as resistant to charcoal rot of soybean. Reactions of 27 maturity group (MG) III, 29 Early MG IV, 34 Late MG IV, and 59 MG V gen...

Association mapping analysis of the response to Macrophomina phaseolina in the Andean Diversity Panel

USDA-ARS?s Scientific Manuscript database

The Andean Diversity Panel was evaluated for response to inoculation with charcoal rot in a field trial in Isabela, Puerto Rico in 2012. The trial was inoculated with backpack sprayers at flowering and a visual evaluation was conducted three weeks later. There was a broad range of response, with abo...

In vitro antagonism of cotton seedlings fungi and characterization of chitinase isozyme activities in Trichoderma harzianum.

PubMed

Asran-Amal, A; Moustafa-Mahmoud, S M; Sabet, K K; El Banna, O H

2010-04-01

The antagonistic fungus Trichoderma harzianum is widely recognized as a potential biocontrol agent against several soil-borne plant pathogens. T. harzinum is rich source of chitinoltic enzymes. In vitro screening of 5 isolates of T. harzinum, one isolate of Chaetomium globosum and one isolate of Conetherium mentance, revealed that all of them had reduced growth area of Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani on PDA medium, significantly. The inhibition percentage ranged from 77.9 % to 55.9% for M. phaseolina and 59.2% to 40.4% for R. solani by T. harzinum and C. mentance, respectively. Inhibition for F. solani ranged from 76.5% to 55.7% by T. harzinum and C. globosum, respectively. Isozyme gel electrophoresis was used to assess chitinase activity secreted by selected isolates of T. harzinum under different pH degrees and temperatures. Obtained results indicated that activity of chitinase isozyme produced at 30 °C was higher than 15-20 °C for all tested isolates and activity of chitinase produced by isolates No. 4 and 5 of T. harzinum at pH (7-7.5) was higher than at pH 6, respectively.

Resistance mechanisms to toxin-mediated charcoal rot infection in maturity group III soybean: role of seed phenol lignin soflavones sugars and seed minerals in charcoal rot resistance

USDA-ARS?s Scientific Manuscript database

Charcoal rot is a disease caused by the fungus Macrophomina phaseolina (Tassi) Goid, and thought to infect the plants through roots by a toxin-mediated mechanism, resulting in yield loss and poor seed quality, especially under drought conditions. The mechanism by which this infection occurs is not y...

Increases in snap bean and soybean seedling diseases associated with a chloride salt and changes in the micro-partitioning of tap root calcium

USDA-ARS?s Scientific Manuscript database

In a series of field experiments from 1995 through 2010, the incidence of seedling diseases of snap bean and soybean caused by Rhizoctonia solani, Macrophomina phaseolina, Pythium spp., and Fusarium spp. was greater with an application of KCl than with K2SO4 applied at 93 kg K/ha. To determine if th...

Draft Genome Sequence of Bacillus cereus CITVM-11.1, a Strain Exhibiting Interesting Antifungal Activities.

PubMed

Caballero, Javier; Peralta, Cecilia; Molla, Antonella; Del Valle, Eleodoro E; Caballero, Primitivo; Berry, Colin; Felipe, Verónica; Yaryura, Pablo; Palma, Leopoldo

2018-01-01

Bacillus cereus is a gram-positive, spore-forming bacterium possessing an important and historical record as a human-pathogenic bacterium. However, several strains of this species exhibit interesting potential to be used as plant growth-promoting rhizobacteria. Here, we report the draft genome sequence of B. cereus strain CITVM-11.1, which consists of 37 contig sequences, accounting for 5,746,486 bp (with a GC content of 34.8%) and 5,752 predicted protein-coding sequences. Several of them could potentially be involved in plant-bacterium interactions and may contribute to the strong antagonistic activity shown by this strain against the charcoal root rot fungus, Macrophomina phaseolina. This genomic sequence also showed a number of genes that may confer this strain resistance against several polluting heavy metals and for the bioconversion of mycotoxins. © 2018 S. Karger AG, Basel.

Control of Root Rot and Wilt Diseases of Roselle under Field Conditions

PubMed Central

Hassan, Naglaa; Elsharkawy, Mohsen Mohamed; Shimizu, Masafumi

2014-01-01

Roselle (Hibiscus sabdariffa L.) is one of the most important medicinal crops in many parts of the world. In this study, the effects of microelements, antioxidants, and bioagents on Fusarium oxysporum, F. solani, and Macrophomina phaseolina, the causal pathogens of root rot and wilt diseases in roselle, were examined under field conditions. Preliminary studies were carried out in vitro in order to select the most effective members to be used in field control trials. Our results showed that microelements (copper and manganese), antioxidants (salicylic acid, ascorbic acid, and EDTA), a fungicide (Dithane M45) and biological control agents (Trichoderma harzianum and Bacillus subtilis) were significantly reduced the linear growth of the causal pathogens. Additionally, application of the previous microelements, antioxidants, a fungicide and biological control agents significantly reduced disease incidence of root rot and wilt diseases under field conditions. Copper, salicylic acid, and T. harzianum showed the best results in this respect. In conclusion, microelements, antioxidants, and biocontrol agents could be used as alternative strategies to fungicides for controlling root rot and wilt diseases in roselle. PMID:25606010

Butyrylcholinesterase, lipoxygenase inhibiting and antifungal alkaloids from Isatis tinctoria.

PubMed

Ahmad, Ijaz; Fatima, Itrat

2008-06-01

Phytochemical investigations on the alkaloidal fraction of the whole plant of the Isatis tinctoria led to the isolation of the alkaloids 1-6. Compounds 3, 2 were found to be potent butyrylcholinesterase and lipoxygenase enzymes inhibitors in a concentration-dependent manner with the IC(50) values 16.3 +/- 0.06 and 19.7 +/- 0.03 microM against BChE and 30.6 +/- 0.02 and 33.7 +/- 0.05 microM against LOX, respectively. The compounds (1-6) showed significant antifungal activity against Trichophyton schoen leinii, Aspergillus niger, Candida albicans, Trichophyton simii, and Macrophomina phaseolina.

Seedborne Pathogenic Fungi in Common Bean (Phaseolus vulgaris cv. INTA Rojo) in Nicaragua.

PubMed

Marcenaro, Delfia; Valkonen, Jari P T

2016-01-01

Common bean (Phaseolus vulgaris L.) is an important legume with high nutritional value. In Nicaragua, certified healthy seeds of local bean varieties are not available, and seedborne fungi have gained little attention. Here, were surveyed seedborne pathogenic fungi in an important local bean cultivar, 'INTA Rojo'. Beans grown in the four main production areas in Nicaragua (Boaco, Carazo, Estelí, Matagalpa) for future use as seed stock were sampled from four seed storehouses and six seed lots. A total of 133 fungal strains were isolated from surface-sterilized beans and inoculated to healthy lima beans (Phaseolus lunatus) under controlled conditions. Eighty-seven isolates caused symptoms of varying severity in the seedlings, including discoloration, necrotic lesions, cankers, rot, and lethal necrosis. Pathogenic isolates were divided into eight phenotypically distinguishable groups based on morphology and growth characteristics on artificial growth medium, and further identified by analysis of the internal transcribed spacer sequences (ITS1 and ITS2) of the ribosomal RNA genes. The pathogenic isolates belonged to eight genera. Fusarium spp. (F. chlamydosporum, F. equiseti, F. incarnatum), Lasiodiplodia theobromae, Macrophomina phaseolina, and Penicillium citrinum were the most damaging and common fungi found in the seed lots. Furthermore, Corynespora cassiicola, Colletotrichum capsisi, Colletotrichum gloeosporioides, Aspergillus flavus, and Diaporthe sp. (Phomopsis) were seedborne in cultivar 'INTA Rojo' and found to be pathogenic to bean seedlings. This study reveals, for the first time, many seedborne pathogenic fungi in beans in Nicaragua; furthermore, prior to this study, little information was available concerning F. equiseti, F. incarnatum, L. theobromae, C. cassiicola, and Diaporthe spp. as seedborne pathogens of common bean. Our results lay the basis for developing diagnostic tools for seed health inspection and for further study of the epidemiology, ecology, and control of the pathogenic fungi of common beans in the field.

Genome-Wide Association Study on Resistance to Stalk Rot Diseases in Grain Sorghum

PubMed Central

Adeyanju, Adedayo; Little, Christopher; Yu, Jianming; Tesso, Tesfaye

2015-01-01

Stalk rots are important biotic constraints to sorghum production worldwide. Several pathogens may be associated with the disease, but Macrophomina phaseolina and Fusarium thapsinum are recognized as the major causal organisms. The diseases become more aggressive when drought and high-temperature stress occur during grain filling. Progress in genetic improvement efforts has been slow due to lack of effective phenotyping protocol and the strong environmental effect on disease incidence and severity. Deployment of modern molecular tools is expected to accelerate efforts to develop resistant hybrids. This study was aimed at identifying genomic regions associated with resistance to both causal organisms. A sorghum diversity panel consisting of 300 genotypes assembled from different parts of the world was evaluated for response to infection by both pathogens. Community resources of 79,132 single nucleotide polymorphic (SNP) markers developed on the panel were used in association studies using a multi-locus mixed model to map loci associated with stalk rot resistance. Adequate genetic variation was observed for resistance to both pathogens. Structure analysis grouped the genotypes into five subpopulations primarily based on the racial category of the genotypes. Fourteen loci and a set of candidate genes appear to be involved in connected functions controlling plant defense response. However, each associated SNP had relatively small effect on the traits, accounting for 19–30% of phenotypic variation. Linkage disequilibrium analyses suggest that significant SNPs are genetically independent. Estimation of frequencies of associated alleles revealed that durra and caudatum subpopulations were enriched for resistant alleles, but the results suggest complex molecular mechanisms underlying resistance to both pathogens. PMID:25882062

Genomic insights into the broad antifungal activity, plant-probiotic properties, and their regulation, in Pseudomonas donghuensis strain SVBP6

PubMed Central

Iriarte, Andrés; Valverde, Claudio Fabián

2018-01-01

Plant-growth promotion has been linked to the Pseudomonas genus since the beginning of this research field. In this work, we mined the genome of an Argentinean isolate of the recently described species P. donghuensis. Strain SVBP6, isolated from bulk soil of an agricultural plot, showed a broad antifungal activity and several other plant-probiotic activities. As this species has been recently described, and it seems like some plant-growth promoting (PGP) traits do not belong to the classical pseudomonads toolbox, we decide to explore the SVBP6 genome via an bioinformatic approach. Genome inspection confirmed our previous in vitro results about genes involved in several probiotic activities. Other genetic traits possibly involved in survival of SVBP6 in highly competitive environments, such as rhizospheres, were found. Tn5 mutagenesis revealed that the antifungal activity against the soil pathogen Macrophomina phaseolina was dependent on a functional gacS gene, from the regulatory cascade Gac-Rsm, but it was not due to volatile compounds. Altogether, our genomic analyses and in vitro tests allowed the phylogenetic assignment and provided the first insights into probiotic properties of the first P. donghuensis isolate from the Americas. PMID:29538430

Expression in Escherichia coli, purification, refolding and antifungal activity of an osmotin from Solanum nigrum

PubMed Central

Campos, Magnólia de A; Silva, Marilia S; Magalhães, Cláudio P; Ribeiro, Simone G; Sarto, Rafael PD; Vieira, Eduardo A; Grossi de Sá, Maria F

2008-01-01

Background Heterologous protein expression in microorganisms may contribute to identify and demonstrate antifungal activity of novel proteins. The Solanum nigrum osmotin-like protein (SnOLP) gene encodes a member of pathogenesis-related (PR) proteins, from the PR-5 sub-group, the last comprising several proteins with different functions, including antifungal activity. Based on deduced amino acid sequence of SnOLP, computer modeling produced a tertiary structure which is indicative of antifungal activity. Results To validate the potential antifungal activity of SnOLP, a hexahistidine-tagged mature SnOLP form was overexpressed in Escherichia coli M15 strain carried out by a pQE30 vector construction. The urea solubilized His6-tagged mature SnOLP protein was affinity-purified by immobilized-metal (Ni2+) affinity column chromatography. As SnOLP requires the correct formation of eight disulfide bonds, not correctly formed in bacterial cells, we adapted an in vitro method to refold the E. coli expressed SnOLP by using reduced:oxidized gluthatione redox buffer. This method generated biologically active conformations of the recombinant mature SnOLP, which exerted antifungal action towards plant pathogenic fungi (Fusarium solani f. sp.glycines, Colletotrichum spp., Macrophomina phaseolina) and oomycete (Phytophthora nicotiana var. parasitica) under in vitro conditions. Conclusion Since SnOLP displays activity against economically important plant pathogenic fungi and oomycete, it represents a novel PR-5 protein with promising utility for biotechnological applications. PMID:18334031

Banana peel culture as an indigenous medium for easy identification of late-sporulation human fungal pathogens.

PubMed

Kindo, A J; Tupaki-Sreepurna, A; Yuvaraj, M

2016-01-01

Fungi are increasing in incidence as human pathogens and newer and rarer species are continuously being encountered. Identifying these species from growth on regular culture media may be challenging due to the absence of typical features. An indigenous and cheap medium, similar to the natural substrate of these fungi, was standardised in our laboratory as an aid to species identification in a conventional laboratory setting. Ripe banana peel pieces, sterilised in an autoclave at 121°C temperature and 15 lbs pressure for 15 min promoted good growth of hyphae and pycnidia or acervuli in coelomycetes, flabelliform and medusoid fruiting bodies of basidiomycetes and fruit bodies such as cleistothecium in ascomycetes. The growth from the primary isolation medium was taken and inoculated onto the pieces of double-autoclaved ripe banana peel pieces in a sterile glass Petri dish with some moisture (sprinkles of sterile distilled water). A few sterile coverslips were placed randomly inside the Petri dish for the growing fungus to stick on to it. The plates were kept at room temperature and left undisturbed for 15-20 days. At a time, one coverslip was taken out and placed on a slide with lactophenol cotton blue and focused under the microscope to look for fruit bodies. Lasiodiplodia theobromae, Macrophomina phaseolina, Nigrospora sphaerica, Chaetomium murorum, Nattrassia mangiferae and Schizophyllum commune were identified by characteristic features from growth on banana peel culture. Banana peel culture is a cheap and effective medium resembling the natural substrate of fungi and is useful for promoting characteristic reproductive structures that aid identification.

Antifungal and phytotoxic activity of essential oil from root of Senecio amplexicaulis Kunth. (Asteraceae) growing wild in high altitude-Himalayan region.

PubMed

Singh, Rajendra; Ahluwalia, Vivek; Singh, Pratap; Kumar, Naresh; Prakash Sati, Om; Sati, Nitin

2016-08-01

This work was aimed to evaluate the essential oil from root of medicinally important plant Senecio amplexicaulis for chemical composition, antifungal and phytotoxic activity. The chemical composition analysed by GC/GC-MS showed the presence of monoterpene hydrocarbons in high percentage with marker compounds as α-phellandrene (48.57%), o-cymene (16.80%) and β-ocimene (7.61%). The essential oil exhibited significant antifungal activity against five phytopathogenic fungi, Sclerotium rolfsii, Macrophomina phaseolina, Rhizoctonia solani, Pythium debaryanum and Fusarium oxysporum. The oil demonstrated remarkable phytotoxic activity in tested concentration and significant reduction in seed germination percentage of Phalaris minor and Triticum aestivum at higher concentrations. The roots essential oil showed high yield for one of its marker compound (α-phellandrene) which makes it important natural source of this compound.

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

NASA Astrophysics Data System (ADS)

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

2016-05-01

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes.

PubMed

Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M Arif

2016-05-15

We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica. Copyright © 2016 Elsevier B.V. All rights reserved.

Biotransformation of a potent anabolic steroid, mibolerone, with Cunninghamella blakesleeana, C. echinulata, and Macrophomina phaseolina, and biological activity evaluation of its metabolites.

PubMed

Siddiqui, Mahwish; Ahmad, Malik Shoaib; Wahab, Atia-Tul-; Yousuf, Sammer; Fatima, Narjis; Naveed Shaikh, Nimra; Rahman, Atta-Ur-; Choudhary, M Iqbal

2017-01-01

Seven metabolites were obtained from the microbial transformation of anabolic-androgenic steroid mibolerone (1) with Cunninghamella blakesleeana, C. echinulata, and Macrophomina phaseolina. Their structures were determined as 10β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (2), 6β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (3), 6β,10β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (4), 11β,17β-dihydroxy-(20-hydroxymethyl)-7α,17α-dimethylestr-4-en-3-one (5), 1α,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (6), 1α,11β,17β-trihydroxy-7α,17α-dimethylestr-4-en-3-one (7), and 11β,17β-dihydroxy-7α,17α-dimethylestr-4-en-3-one (8), on the basis of spectroscopic studies. All metabolites, except 8, were identified as new compounds. This study indicates that C. blakesleeana, and C. echinulata are able to catalyze hydroxylation at allylic positions, while M. phaseolina can catalyze hydroxylation of CH2 and CH3 groups of substrate 1. Mibolerone (1) was found to be a moderate inhibitor of β-glucuronidase enzyme (IC50 = 42.98 ± 1.24 μM) during random biological screening, while its metabolites 2-4, and 8 were found to be inactive. Mibolerone (1) was also found to be significantly active against Leishmania major promastigotes (IC50 = 29.64 ± 0.88 μM). Its transformed products 3 (IC50 = 79.09 ± 0.06 μM), and 8 (IC50 = 70.09 ± 0.05 μM) showed a weak leishmanicidal activity, while 2 and 4 were found to be inactive. In addition, substrate 1 (IC50 = 35.7 ± 4.46 μM), and its metabolite 8 (IC50 = 34.16 ± 5.3 μM) exhibited potent cytotoxicity against HeLa cancer cell line (human cervical carcinoma). Metabolite 2 (IC50 = 46.5 ± 5.4 μM) also showed a significant cytotoxicity, while 3 (IC50 = 107.8 ± 4.0 μM) and 4 (IC50 = 152.5 ± 2.15 μM) showed weak cytotoxicity against HeLa cancer cell line. Compound 1 (IC50 = 46.3 ± 11.7 μM), and its transformed products 2 (IC50 = 43.3 ± 7.7 μM), 3 (IC50 = 65.6 ± 2.5 μM), and 4 (IC50 = 89.4 ± 2.7 μM) were also found to be moderately toxic to 3T3 cell line (mouse fibroblast). Interestingly, metabolite 8 showed no cytotoxicity against 3T3 cell line. Compounds 1-4, and 8 were also evaluated for inhibition of tyrosinase, carbonic anhydrase, and α-glucosidase enzymes, and all were found to be inactive.

Effect of seed pelleting with biocontrol agents on growth and colonisation of roots of mungbean by root-infecting fungi.

PubMed

Ramzan, Nadia; Noreen, Nayara; Perveen, Zahida; Shahzad, Saleem

2016-08-01

Mungbean (Vigna radiata (L.) Wilczek) is a leguminous pulse crop that is a major source of proteins, vitamins and minerals. Root-infecting fungi produce severe plant diseases like root rot, charcoal rot, damping-off and stem rot. The soil-borne pathogens can be controlled by chemicals, but these chemicals have several negative effects. Use of microbial antagonist such as fungi and bacteria is a safe, effective and eco-friendly method for the control of many soil-borne pathogens. Biological control agents promote plant growth and develop disease resistance. Application of bacteria and fungi as seed dressing suppressed the root-infecting fungi on leguminous crops. Seeds of mungbean were pelleted with different biocontrol agents to determine their effect on plant growth and colonisation of roots by root-infecting fungi, viz. Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani and Sclerotium rolfsii. Treatment of mungbean seeds with fungal antagonists showed more shoot and root length as compared to bacterial antagonists, whereas seed treated with bacterial antagonists showed maximum shoot and root weight. Trichoderma harzianum and Bacillus subtilis were the best among all the biocontrol agents since they provided the highest plant growth and greater reduction in root colonisation by all root-infecting fungi. Bacillus cereus, Trichoderma virens, Pseudomonas fluorescens and Micrococcus varians were also effective against root-infecting fungi but to a lesser extent. T. harzianum, T. virens, B. subtilis and P. fluorescens were found to be best among all biocontrol agents. The root-infecting fungi can be controlled by pelleting seeds with biocontrol agents as it is safe and effective method. Additionally, plant growth was promoted more by this method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Biotransformation of dianabol with the filamentous fungi and β-glucuronidase inhibitory activity of resulting metabolites.

PubMed

Khan, Naik T; Zafar, Salman; Noreen, Shagufta; Al Majid, Abdullah M; Al Othman, Zeid A; Al-Resayes, Saud Ibrahim; Atta-ur-Rahman; Choudhary, M Iqbal

2014-07-01

Biotransformation of the anabolic steroid dianabol (1) by suspended-cell cultures of the filamentous fungi Cunninghamella elegans and Macrophomina phaseolina was studied. Incubation of 1 with C. elegans yielded five hydroxylated metabolites 2-6, while M. phaseolina transformed compound 1 into polar metabolites 7-11. These metabolites were identified as 6β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (2), 15α,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (3), 11α,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (4), 6β,12β,17β-trihydroxy-17α-methylandrost-1,4-dien-3-one (5), 6β,15α,17β-trihydroxy-17α-methylandrost-1,4-dien-3-one (6), 17β-hydroxy-17α-methylandrost-1,4-dien-3,6-dione (7), 7β,17β,-dihydroxy-17α-methylandrost-1,4-dien-3-one (8), 15β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (9), 17β-hydroxy-17α-methylandrost-1,4-dien-3,11-dione (10), and 11β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (11). Metabolite 3 was also transformed chemically into diketone 12 and oximes 13, and 14. Compounds 6 and 12-14 were identified as new derivatives of dianabol (1). The structures of all transformed products were deduced on the basis of spectral analyses. Compounds 1-14 were evaluated for β-glucuronidase enzyme inhibitory activity. Compounds 7, 13, and 14 showed a strong inhibition of β-glucuronidase enzyme, with IC50 values between 49.0 and 84.9 μM. Copyright © 2014 Elsevier Inc. All rights reserved.

Tandem mass spectrometry approach for the investigation of the steroidal metabolism: structure-fragmentation relationship (SFR) in anabolic steroids and their metabolites by ESI-MS/MS analysis.

PubMed

Musharraf, Syed Ghulam; Ali, Arslan; Khan, Naik Tameem; Yousuf, Maria; Choudhary, Muhammad Iqbal; Atta-ur-Rahman

2013-02-01

Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to investigate the effect of different substitutions introduced during metabolism on fragmentation patterns of four anabolic steroids including methyltestosterone, methandrostenolone, cis-androsterone and adrenosterone, along with their metabolites. Collision-induced dissociation (CID) analysis was performed to correlate the major product ions of 19 steroids with structural features. The analysis is done to portray metabolic alteration, such as incorporation or reduction of double bonds, hydroxylations, and/or oxidation of hydroxyl moieties to keto functional group on steroidal skeleton which leads to drastically changed product ion spectra from the respective classes of steroids, therefore, making them difficult to identify. The comparative ESI-MS/MS study also revealed some characteristic peaks to differentiate different steroidal metabolites and can be useful for the unambiguous identification of anabolic steroids in biological fluid. Moreover, LC-ESI-MS/MS analysis of fermented extract of methyltestosterone, obtained by Macrophomina phaseolina was also investigated. Copyright © 2012 Elsevier Inc. All rights reserved.

Integrated approach for disease management and growth enhancement of Sesamum indicum L. utilizing Azotobacter chroococcum TRA2 and chemical fertilizer.

PubMed

Maheshwari, D K; Dubey, R C; Aeron, Abhinav; Kumar, Bhavesh; Kumar, Sandeep; Tewari, Sakshi; Arora, Naveen Kumar

2012-10-01

Azotobacter chroococcum TRA2, an isolate of wheat rhizosphere displayed plant growth promoting attributes including indole acetic acid, HCN, siderophore production, solubilization of inorganic phosphate and fixation of atmospheric nitrogen. In addition, it showed strong antagonistic effect against Macrophomina phaseolina and Fusarium oxysporum. It also caused degradation and digestion of cell wall components, resulting in hyphal perforations, empty cell (halo) formation, shrinking and lysis of fungal mycelia along with significant degeneration of conidia. Fertilizer adaptive variant strain of A. chroococcum TRA2 was studied with Tn5 induced streptomycin resistant transconjugants of wild type tetracycline-resistant TRA2 (designated TRA2(tetra+strep+)) after different durations. The strain was significantly competent in rhizosphere, as its population increased by 15.29 % in rhizosphere of Sesamum indicum. Seed bacterization with the strain TRA2 resulted in significant increase in vegetative growth parameters and yield of sesame over the non-bacterized seeds. However, application of TRA2 with half dose of fertilizers showed sesame yield almost similar to that obtained by full dose treatment. Moreover, the oil yield increased by 24.20 %, while protein yield increased by 35.92 % in treatment receiving half dose of fertilizer along with TRA2 bacterized seeds, as compared to untreated control.

Effects of nematicides on cotton root mycobiota.

PubMed

Baird, R E; Carling, D E; Watson, C E; Scruggs, M L; Hightower, P

2004-02-01

Baseline information on the diversity and population densities of fungi collected from soil debris and cotton (Gossypium hirsutum L.) roots was determined. Samples were collected from Tifton, GA, and Starkville, MS containing cotton field soil treated with the nematicides 1,3-dichloroproprene (fumigant) and aldicarb (granules). A total of 10,550 and 13,450 fungal isolates were collected from these two study sites, respectively. Of this total, 34 genera of plant pathogenic or saprophytic species were identified. Pathogenic root fungi included Fusarium spp. (40% of all isolations), Macrophomina, Pythium, Rhizoctonia, and Sclerotium. Fusarium and Rhizoctonia were the most common fungal species identified and included F. oxysporum, F. verticillioides and F. solani, the three Fusarium species pathogenic on cotton plants. Population densities of Fusarium were not significantly different among locations or tissue types sampled. Macrophomina was isolated at greater numbers near the end of the growing seasons. Anastomosis groups of R. solani isolated from roots and soil debris included AG-3, -4, -7, 2-2, and -13 and anastomosis groups of binucleate Rhizoctonia included CAG-2, -3, and -5. Occurrences and frequency of isolations among sampling dates were not consistent. Fluctuations in the frequency of isolation of Rhizoctonia did not correspond with changes in frequency of isolation of the biological control fungus, Trichoderma. When individual or pooled frequencies of the mycobiota were compared to nematicide treatments, no specific trends occurred between treatments, application methods or rates. Results from this study show that use of 1,3-D and aldicarb in cotton fields does not significantly impact plant pathogenic fungi or saprophytic fungal populations. Thus cotton producers need not adjust seedling disease control measures when these two nematicides are used.

Incidence of diverse dsRNA mycoviruses in Trichoderma spp. causing green mold disease of shiitake Lentinula edodes.

PubMed

Yun, Suk-Hyun; Lee, Song Hee; So, Kum-Kang; Kim, Jung-Mi; Kim, Dae-Hyuk

2016-09-22

A total of 315 fungal isolates causing green mold disease were collected from contaminated artificial logs and sawdust bags used for cultivating shiitake Lentinula edodes in Korea and were analyzed for the presence of double-stranded RNA (dsRNA). dsRNA, which was purified using dsRNA-specific chromatography and verified by dsRNA-specific RNaseIII digestion, was detected in 32 isolates. The molecular taxonomy of dsRNA-infected isolates indicated that all isolates belonged to the Trichoderma spp.. The number and size of dsRNAs varied among isolates and the band patterns could be categorized into 15 groups. Although there were seven dsRNA groups observed in multiple isolates, eight groups were found to occur in single isolates. The most common dsRNA group, group VI, which contained a band of 10 kb, occurred in 10 isolates encompassing three species of Trichoderma Partial sequence analysis of two selected dsRNA groups revealed a high degree of similarity to sequences of a RNA-dependent RNA polymerase, hypothetical protein, and polyprotein genes of other hypoviruses such as Macrophomina phaseolina hypovirus 1, Trichoderma hypovirus, and Fusarium graminearum hypovirus 2, respectively, indicating the occurrence of mycoviruses in Trichoderma spp.. Northern blot analysis suggested that many different mycoviruses, which have not been identified yet, exist in Trichoderma. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Influence of simulated acidic rain on root-infecting fungi

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

Shafer, S.R.

1983-01-01

Influences of the acidity of simulated rain on root-infecting fungi were investigated. Effects of rain acidity on Phytophthora cinnamomi were studied. Propagule densities in soil depended upon the acidity (pH 5.6, 4.0, 3.2, or 2.4) of simulated rain and soil depth (1, 2, 4, or 8 cm). Lowest densities occurred in 1 to 2 cm soil layers exposed to rains at pH 3.2 or 2.4. Sporangium production on radicles of Lupinus angustifolius in Lakeland sand moistened with rain solution at pH 2.4 was 47% less than production with solution at pH 5.6. A linear response to solution acidity was exhibited.more » Infection of L. angustifolius roots by zoospores demonstrated a linear response to acidity of rain. Approximately 44% fewer lesions occurred on roots of seedlings exposed to rain at pH 2.4 than on roots of seedlings exposed to rain at pH 5.6. The acidity (pH 5.6, 4.0, 3.2, or 2.4) of repeated rains had no consistent effect on disease progress among L. augustifolius seedlings planted in infested soil. The formation of ectomycorrhizae on Pinus taeda seedlings exhibited a quadratic response to acidity of repeated rains. The percentage of short roots that were ectomycorrhizal was greatest among seedlings exposed to rains at pH 2.4 and least among seedlings exposed to rains at pH 4.0. The density of Macrophomina phaseolina propagules in Lakeland sand exposed to repeated rains at pH 2.4 was an average of 20% less than densities associated with rains at pH 5.6, 4.0, or 3.2.« less

In vitro comparative analysis of monocrotophos degrading potential of Aspergillus flavus, Fusarium pallidoroseum and Macrophomina sp.

PubMed

Jain, Rachna; Garg, Veena; Yadav, Deepak

2014-06-01

Fungal degradation is emerging as a new powerful tool for the removal of potent neurotoxin pesticide, monocrotophos. Therefore, the present study is aimed at comparative characterization of monocrotophos degrading ability of three different fungal strains. Fungal strains were isolated from local agricultural soil by enrichment culture method, screened by gradient culture and identified as Aspergillus flavus, Fusarium pallidoroseum and Macrophomina sp. Growth kinetics revealed a direct positive influence of monocrotophos on the viability of fungal isolates. Fungal degradation was studied in phosphorus free liquid culture medium supplemented with 150 mg L(-1) concentration of monocrotophos for a period of 15 days under optimized culture conditions. Degradation of MCP followed first order kinetics with kdeg of 0.007, 0.002 and 0.005 day(-1) and half life (t1/2) of 4.21, 12.64 and 6.32 days for A. flavus, F. pallidoroseum and Macrophomina sp. respectively. To the best of our knowledge, it is the first report signifying the potential of monocrotophos degradation by Fusarium and Macrophomina sp. The results were further confirmed by HPTLC and FTIR which indicates disappearance of monocrotophos by hydrolytic cleavage of vinyl phosphate bond. Degradation of monocrotophos by fungal isolates was accompanied by the release of extracellular alkaline phosphatases, inorganic phosphates and ammonia. The overall comparative analysis followed the order of A. flavus > Macrophomina sp. > F. pallidoroseum. Therefore, it could be concluded from the study that these three different fungal strains could be effectively used as a potential candidate for the removal of monocrotophos from contaminated sites.

Fungal Endophyte Diversity and Bioactivity in the Indian Medicinal Plant Ocimum sanctum Linn

PubMed Central

Chowdhary, Kanika; Kaushik, Nutan

2015-01-01

Endophytic mycopopulation isolated from India’s Queen of herbs Tulsi (Ocimum sanctum) were explored and investigated for their diversity and antiphytopathogenic activity against widespread plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani and Fusarium oxysporum. 90 fungal isolates, representing 17 genera were recovered from 313 disease-free and surface sterilised plant segments (leaf and stem tissues) from three different geographic locations (Delhi, Hyderabad and Mukteshwar) during distinct sampling times in consequent years 2010 and 2011 in India. Fungal endophytes were subjected to molecular identification based on rDNA ITS sequence analysis. Plant pathogens such as F. verticillioides, B. maydis, C. coarctatum, R. bataticola, Hypoxylon sp., Diaporthe phaseolorum, Alternaria tenuissima and A. alternata have occurred as endophyte only during second sampling (second sampling in 2011) in the present study. Bi-plot generated by principal component analysis suggested tissue specificity of certain fungal endophytes. Dendrogram revealed species abundance as a function of mean temperature of the location at the time of sampling. Shannon diversity in the first collection is highest in Hyderabad leaf tissues (H' = 1.907) whereas in second collection it was highest from leaf tissues of Delhi (H' = 1.846). Mukteshwar (altitude: 7500 feet) reported least isolation rate in second collection. Nearly 23% of the total fungal isolates were considered as potent biocontrol agent. Hexane extract of M. phaseolina recovered from Hyderabad in first collection demonstrated highest activity against S. sclerotiorum with IC50 value of 0.38 mg/ml. Additionally, its components 2H-pyran-2-one, 5,6-dihydro-6-pentyl and palmitic acid, methyl ester as reported by GC-MS Chromatogram upon evaluation for their antiphytopathogenic activity exhibited IC50 value of 1.002 and 0.662 against respectively S. sclerotiorum indicating their significant role in antiphytopathogenic activity of hexane extract. The production of 2H-pyran-2-one, 5,6-dihydro-6-pentyl from M. phaseolina, an endophytic fungus is being reported for the first time. PMID:26529087

Evolutionary diversification of the bean beetle genus Callosobruchus (Coleoptera: Bruchidae): traits associated with stored-product pest status.

PubMed

Tuda, M; Rönn, J; Buranapanichpan, S; Wasano, N; Arnqvist, G

2006-10-01

Despite the fact that many plant-feeding insects are pests, little effort has been made to identify key evolutionary trait transitions that allow taxa to acquire or lose pest status. A large proportion of species in the genus Callosobruchus are economically important pests of stored, dry postharvest beans of the tribe Phaseoleae. However, the evolution of this feeding habit is poorly understood. Here, we present a reconstruction of the phylogeny of the Asian and African Callosobruchus based on three mitochondrial genes, and assess which traits have been associated with the evolutionary origin or loss of ability to reproduce on dry beans. Our phylogenetic analysis showed that species group into the chinensis and the maculatus clades, which are also supported by genital morphology, and an additional paraphyletic group. Ancestral ability to use dry beans has been lost in the chinensis clade but acquired again in C. chinensis. Dry-bean use and host-plant use were both phylogenetically constrained and transitions in the two were significantly correlated. Host shifts from the subtribe Phaseolinae to Cajaninae were more common than the reverse and were more likely in species using young beans. The ability to use dry beans was more likely gained when using Phaseolinae hosts and promoted habitat shifts from tropical to temperate regions. Adaptation to arid climate was also associated with the ability to reproduce on dry beans and on Phaseolinae. Thus, our analysis suggests that physiological adaptations to an arid climate and to Phaseolinae hosts both render beetles predisposed to become pests of cultivated beans.

Synthesis of some potent immunomodulatory and anti-inflammatory metabolites by fungal transformation of anabolic steroid oxymetholone

PubMed Central

2012-01-01

Background Biotransformation of organic compounds by using microbial whole cells provides an efficient approach to obtain novel analogues which are often difficult to synthesize chemically. In this manuscript, we report for the first time the microbial transformation of a synthetic anabolic steroidal drug, oxymetholone, by fungal cell cultures. Results Incubation of oxymetholone (1) with Macrophomina phaseolina, Aspergillus niger, Rhizopus stolonifer, and Fusarium lini produced 17β-hydroxy-2-(hydroxy-methyl)-17α-methyl-5α-androstan-1-en-3-one (2), 2α,17α-di(hydroxyl-methyl)-5α-androstan-3β,17β-diol (3), 17α-methyl-5α-androstan-2α,3β,17β-triol (4), 17β-hydroxy-2-(hydroxymethyl)-17α-methyl-androst-1,4-dien-3-one (5), 17β-hydroxy-2α-(hydroxy-methyl)-17α-methyl-5α-androstan-3-one (6), and 2α-(hydroxymethyl)-17α-methyl-5α-androstan-3β-17β-diol (7). Their structures were deduced by spectral analyses, as well as single-crystal X-ray diffraction studies. Compounds 2–5 were identified as the new metabolites of 1. The immunomodulatory, and anti-inflammatory activities and cytotoxicity of compounds 1–7 were evaluated by observing their effects on T-cell proliferation, reactive oxygen species (ROS) production, and normal cell growth in MTT assays, respectively. These compounds showed immunosuppressant effect in the T-cell proliferation assay with IC50 values between 31.2 to 2.7 μg/mL, while the IC50 values for ROS inhibition, representing anti-inflammatory effect, were in the range of 25.6 to 2.0 μg/mL. All the compounds were found to be non-toxic in a cell-based cytotoxicity assay. Conclusion Microbial transformation of oxymetholone (1) provides an efficient method for structural transformation of 1. The transformed products were obtained as a result of de novo stereoselective reduction of the enone system, isomerization of double bond, insertion of double bond and hydroxylation. The transformed products, which showed significant immunosuppressant and anti-inflammatory activities, can be further studied for their potential as novel drugs. PMID:23237028

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes.

PubMed

Solans, Mariana; Scervino, Jose Martin; Messuti, María Inés; Vobis, Gernot; Wall, Luis Gabriel

2016-11-01

Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of protoplast fusion between two Trichoderma spp. on extracellular enzymes production and antagonistic activity.

PubMed

Hassan, Mohamed M

2014-11-02

Biological control plays a crucial role in grapevine pathogens disease management. The cell-wall degrading enzymes chitinase, cellulase and β-glucanase have been suggested to be essential for the mycoparasitism activity of Trichoderma species against grapevine fungal pathogens. In order to develop a useful strain as a single source of these vital enzymes, it was intended to incorporate the characteristics of two parental fungicides tolerant mutants of Trichoderma belonging to the high chitinase producing species T. harzianum and the high cellulase producing species T. viride , by fusing their protoplasts. The phylogeny of the parental strains was carried out using a sequence of the 5.8S-ITS region. The BLAST of the obtained sequence identified these isolates as T. harzianum and T. viride . Protoplasts were isolated using lysing enzymes and were fused using polyethylene glycol. The fused protoplasts have been regenerated on protoplast regeneration minimal medium supplemented with two selective fungicides. Among the 40 fast growing fusants, 17 fusants were selected based on their enhanced growth on selective media for further studies. The fusant strains were growing 60%-70% faster than the parents up to third generation. All the 17 selected fusants exhibited morphological variations. Some fusant strains displayed threefold increased chitinase enzyme activity and twofold increase in β-glucanase enzyme activity compared to the parent strains. Most fusants showed powerful antagonistic activity against Macrophomin aphaseolina , Pythium ultimum and Sclerotium rolfsii pathogens. Fusant number 15 showed the highest inhibition percentage (92.8%) against M. phaseolina and P. ultimum, while fusant number 9 showed the highest inhibition percentage (98.2%) against the growth of S. rolfsii. A hyphal intertwining and degradation phenomenon was observed by scanning electron microscope. The Trichoderma antagonistic effect against pathogenic fungal mycelia was due to the mycoparasitism effect of the extracellular enzymes.

Evaluation of soybean genotypes for resistance to three seed borne diseases

USDA-ARS?s Scientific Manuscript database

Seed-borne diseases of soybeans caused by Phomopsis longicolla (Phomopsis seed decay), Cercospora kukuchii (purple seed stain), and M. phaseolina (charcoal rot) are economically important seed-borne diseases that affect seed quality. Commercial cultivars marketed as resistant to all the three disea...

Influence of protoplast fusion between two Trichoderma spp. on extracellular enzymes production and antagonistic activity

PubMed Central

Hassan, Mohamed M.

2014-01-01

Biological control plays a crucial role in grapevine pathogens disease management. The cell-wall degrading enzymes chitinase, cellulase and β-glucanase have been suggested to be essential for the mycoparasitism activity of Trichoderma species against grapevine fungal pathogens. In order to develop a useful strain as a single source of these vital enzymes, it was intended to incorporate the characteristics of two parental fungicides tolerant mutants of Trichoderma belonging to the high chitinase producing species T. harzianum and the high cellulase producing species T. viride, by fusing their protoplasts. The phylogeny of the parental strains was carried out using a sequence of the 5.8S-ITS region. The BLAST of the obtained sequence identified these isolates as T. harzianum and T. viride. Protoplasts were isolated using lysing enzymes and were fused using polyethylene glycol. The fused protoplasts have been regenerated on protoplast regeneration minimal medium supplemented with two selective fungicides. Among the 40 fast growing fusants, 17 fusants were selected based on their enhanced growth on selective media for further studies. The fusant strains were growing 60%–70% faster than the parents up to third generation. All the 17 selected fusants exhibited morphological variations. Some fusant strains displayed threefold increased chitinase enzyme activity and twofold increase in β-glucanase enzyme activity compared to the parent strains. Most fusants showed powerful antagonistic activity against Macrophomin aphaseolina, Pythium ultimum and Sclerotium rolfsii pathogens. Fusant number 15 showed the highest inhibition percentage (92.8%) against M. phaseolina and P. ultimum, while fusant number 9 showed the highest inhibition percentage (98.2%) against the growth of S. rolfsii. A hyphal intertwining and degradation phenomenon was observed by scanning electron microscope. The Trichoderma antagonistic effect against pathogenic fungal mycelia was due to the mycoparasitism effect of the extracellular enzymes. PMID:26019588

Population diversity of bacterial endophytes from jute (Corchorus olitorius) and evaluation of their potential role as bioinoculants.

PubMed

Haidar, Badrul; Ferdous, Mahbuba; Fatema, Babry; Ferdous, Ahlan Sabah; Islam, Mohammad Riazul; Khan, Haseena

2018-03-01

Endophytes are bacterial or fungal organisms associated with plants in an obligate or facultative manner. In order to maintain a stable symbiosis, many of the endophytes produce compounds that promote plant growth and help them adapt better to the environment. This study was conducted to explore the potential of jute bacterial endophytes for their growth promotion ability in direct and indirect ways. A total of 27 different bacterial species were identified from different varieties of a jute plant (Corchorus olitorius) and different parts of the plant (leaf, root, seed, and seedling) based on 16S rRNA gene sequence. Two of the isolates showed ACC deaminase activity with Staphylococcus pasteuri strain MBL_B3 and Ralstonia solanacearum strain MBL_B6 producing 18.1 and 8.08 μM mg -1  h -1 α-ketobutyrate respectively while eighteen had the ACC deaminase gene (acdS). Fourteen were positive for siderophore activity while Kocuria sp. strain MBL_B19 (133.36 μg/ml) and Bacillus sp. strain MBL_B17 (124.72 μg/ml) showed high IAA production ability. Seven bacterial strains were able to fix nitrogen with only one testing positive for nifH gene. Five isolates exhibited phosphorus utilization ability with Bacillus sp. strain MBL_B17 producing 218.47 μg P/ml. Three bacteria were able to inhibit the growth of a phytopathogen, Macrophomina phaseolina and among them Bacillus subtilis strain MBL_B4 was found to be the most effective, having 82% and 53% of relative inhibition ratio (RIR) and percent growth inhibition (PGI) values respectively. Nine bacteria were tested for their in vivo growth promotion ability and most of these isolates increased seed germination potential and vigour index significantly. Bacillus subtilis strain MBL_B13 showed 26.8% more vigour index than the control in which no bacterial inoculum was used. All inoculants were found to increase the dry weight of jute seedlings in comparison to the control plants and the most increase in fresh weight was found for Staphylococcus saprophyticus strain MBL_B9. Staphylococcus pasteuri strain MBL_B3 exhibited diverse in vitro growth promotion activity and significant growth promoting effect in in vivo pot experiments. These bacterial strains with plant growth enhancing abilities have the potential to be used as bioinoculants. Copyright © 2018 Elsevier GmbH. All rights reserved.

Enzymatic degradation of monocrotophos by extracellular fungal OP hydrolases.

PubMed

Jain, Rachna; Garg, Veena

2013-11-01

The present study explores the potential of extracellular fungal organophosphate (OP) hydrolase for the degradation of monocrotophos. Extracellular OP hydrolases were isolated and purified from five different fungal isolates viz. Aspergillus niger (M1), Aspergillus flavus (M2), Penicillium aculeatum (M3), Fusarium pallidoroseum (M4), and Macrophomina sp. (M5) by AmSO4 precipitation, dialysis, and G-100 chromatography. M3 showed highest percentage yield of 68.81 followed by 55.41 % for M1. Each of the purified enzyme fraction constituted of two different subunits of 33- and 67-kDa molecular weight. Optimum enzyme fraction (150 μg ml(-1)) rapidly degraded monocrotophos within 120 h in phosphorus-free liquid culture medium (CZM) with K deg of 0.0368, 0.0138, 0.048, 0.016, 0.0138, and 0.048 day(-1) and half-life of 0.79, 2.11, 0.6, 1.8, and 2.11 days for M1, M2, M3, M4, and M5, respectively. The results were further confirmed by high performance thin layer chromatography and Fourier transform infrared which indicate the disappearance of monocrotophos by hydrolytic cleavage of vinyl phosphate bond. The overall order of enzymatic degradation was found to be P. aculeatum > A. niger > F. pallidoroseum > A. flavus = Macrophomina sp. Hence, the study concludes that extracellular OP hydrolases efficiently degraded monocrotophos and could be used as a potential candidate for the detoxification of this neurotoxin pesticide.

Improved Shoot Regeneration, Salinity Tolerance and Reduced Fungal Susceptibility in Transgenic Tobacco Constitutively Expressing PR-10a Gene.

PubMed

Agarwal, Parinita; Dabi, Mitali; More, Prashant; Patel, Khantika; Jana, Kalyanashis; Agarwal, Pradeep K

2016-01-01

Plants in ecosystems are simultaneously exposed to abiotic and biotic stresses, which restrict plant growth and development. The complex responses to these stresses are largely regulated by plant hormones, which in turn, orchestrate the different biochemical and molecular pathways to maneuver stress tolerance. The PR-10 protein family is reported to be involved in defense regulation, stress response and plant growth and development. The JcPR-10a overexpression resulted in increased number of shoot buds in tobacco (Nicotiana tabacum), which could be due to high cytokinin to auxin ratio in the transgenics. The docking analysis shows the binding of three BAP molecules at the active sites of JcPR-10a protein. JcPR-10a transgenics showed enhanced salt tolerance, as was evident by increased germination rate, shoot and root length, relative water content, proline, soluble sugar and amino acid content under salinity. Interestingly, the transgenics also showed enhanced endogenous cytokinin level as compared to WT, which, further increased with salinity. Exposure of gradual salinity resulted in increased stomatal conductance, water use efficiency, photosynthesis rate and reduced transpiration rate. Furthermore, the transgenics also showed enhanced resistance against Macrophomina fungus. Thus, JcPR-10a might be working in co-ordination with cytokinin signaling in mitigating the stress induced damage by regulating different stress signaling pathways, leading to enhanced stress tolerance.

Physiological aspects of fungi isolated from root nodules of faba bean (Vicia faba L.).

PubMed

Omar, S A; Abd-Alla, M H

2000-03-01

The present study was made to isolate and assess some physiological characteristics of root nodule-colonizing fungi. During this study, 17 fungal species were isolated from root nodule samples taken from faba bean plants (Vicia faba L.) collected from different sites at Assiut area (Egypt). The growth of faba bean plants in pots was significantly promoted by soil inoculation with most fungi. Growth was checked in pots with inocula of Cladosporium cladosporioides, Fusarium moniliforme, F: oxysporium, F solani, Macrophominia phaseolina and Rhizoctonia solani which were added separately. All growth-promoting fungi were capable of producing cellulase, pectin lyase, polygalacturonase, protease, urease, amidase, acid phosphatase, alkaline phosphatase and arylsulfatase in growth medium supplemented with the corresponding substrates. Four fungal species, Aspergillus awamori, A. flavus, Penicillium chrysogenum and Trichoderma koningii showed the highest rates of enzyme formation. The effect of the addition of six trace elements to the growth media at 30 micromol/ml on enzyme production revealed some dependency on species, enzyme and metal ion. Cd2+, Hg2+ and Zn2+ generally inhibited enzyme activity. Cu(1+), Fe3+ and Al3+ showed a stimulatory effect. Fungicides (afugan and tilt) and herbicides (brominal and fusilade) at 50 ppm generally promoted enzyme activity, but insecticides (kelthane and fenvalerate) caused some inhibition to enzyme activities. Salinization of the growth media with NaCl strongly inhibited the enzymatic activity of all fungi at concentrations between 0.5 and 1.5%.

The normal mycoflora of commodities from Thailand. 1. Nuts and oilseeds.

PubMed

Pitt, J I; Hocking, A D; Bhudhasamai, K; Miscamble, B F; Wheeler, K A; Tanboon-Ek, P

1993-12-01

A comprehensive study was carried out of the fungi occurring in commodities normally traded in Thailand. Samples of major commodities were obtained from farmers' stocks and middlemen in major producing areas throughout the country. Retail samples were obtained from outlets in and around Bankok. Samples were divided into two portions, one being examined in Bangkok, and the second in Sydney. After surface disinfection, fungi were enumerated by direct plating on dichloran rose bengal chloramphenicol agar, dichloran 18% glycerol agar, Aspergillus flavus and parasiticus agar and dichloran chloramphenicol peptone agar. Figures for percentage infection were calculated, and fungi were isolated and identified to species level. In all 602 samples were examined, and at North Ryde about 18,000 fungal isolates identified. Data obtained from 329 samples are reported here, comprising maize (154), peanuts (109), cashews (45) and copra (21). Major fungi in maize included Fusarium moniliforme (present in 97% of samples), Aspergillus flavus (85%), Penicillium citrinum (67%), Aspergillus niger (64%), Lasiodiplodia theobromae (58%) and Fusarium semitectum (45%). In peanuts, the major fungi were Aspergillus flavus (95% of samples), Aspergillus niger (86%), Rhizopus oryzae (60%), Eurotium rubrum (51%), Macromina phaseolina (49%), Penicillium citrinum (46%) and Eurotium chevalieri (46%). Invasion in cashews was lower, major fungi being Aspergillus flavus (60%), Nigrospora oryzae (58%), Aspergillus niger (53%), Chaetomium globosum (47%) and Eurotium chevalieri (40%). Aspergillus flavus (86% of samples) was again dominant in copra, with Rhizopus oryzae (52%), Aspergillus niger (43%), Eurotium chevalieri (43%) the only other species exceeding 40% infection. Aspergillus parasiticus was rarely seen, and Aspergillus nomius was reported from foods for the first time.

Phylogenetic lineages in the Botryosphaeriaceae

PubMed Central

Crous, Pedro W.; Slippers, Bernard; Wingfield, Michael J.; Rheeder, John; Marasas, Walter F.O.; Philips, Alan J.L.; Alves, Artur; Burgess, Treena; Barber, Paul; Groenewald, Johannes Z.

2006-01-01

Botryosphaeria is a species-rich genus with a cosmopolitan distribution, commonly associated with dieback and cankers of woody plants. As many as 18 anamorph genera have been associated with Botryosphaeria, most of which have been reduced to synonymy under Diplodia (conidia mostly ovoid, pigmented, thick-walled), or Fusicoccum (conidia mostly fusoid, hyaline, thin-walled). However, there are numerous conidial anamorphs having morphological characteristics intermediate between Diplodia and Fusicoccum, and there are several records of species outside the Botryosphaeriaceae that have anamorphs apparently typical of Botryosphaeria s.str. Recent studies have also linked Botryosphaeria to species with pigmented, septate ascospores, and Dothiorella anamorphs, or Fusicoccum anamorphs with Dichomera synanamorphs. The aim of this study was to employ DNA sequence data of the 28S rDNA to resolve apparent lineages within the Botryosphaeriaceae. From these data, 12 clades are recognised. Two of these lineages clustered outside the Botryosphaeriaceae, namely Diplodia-like anamorphs occurring on maize, which are best accommodated in Stenocarpella (Diaporthales), as well as an unresolved clade including species of Camarosporium/Microdiplodia. We recognise 10 lineages within the Botryosphaeriaceae, including an unresolved clade (Diplodia/Lasiodiplodia/Tiarosporella), Botryosphaeria s.str. (Fusicoccum anamorphs), Macrophomina, Neoscytalidium gen. nov., Dothidotthia (Dothiorella anamorphs), Neofusicoccum gen. nov. (Botryosphaeria-like teleomorphs, Dichomera-like synanamorphs), Pseudofusicoccum gen. nov., Saccharata (Fusicoccum- and Diplodia-like synanamorphs), “Botryosphaeria” quercuum (Diplodia-like anamorph), and Guignardia (Phyllosticta anamorphs). Separate teleomorph and anamorph names are not provided for newly introduced genera, even where both morphs are known. The taxonomy of some clades and isolates (e.g. B. mamane) remains unresolved due to the absence of ex-type cultures. PMID:18490983

Molecular cloning and characterization of a group II WRKY transcription factor from Jatropha curcas, an important biofuel crop.

PubMed

Agarwal, Parinita; Dabi, Mitali; Agarwal, Pradeep K

2014-08-01

The WRKY family of transcription factors (TFs) play an intricate role in regulating the stress signaling pathways by autoregulation or may be by cross regulation through interaction with other proteins. Although WRKY TFs are considered to be plant specific, however, their presence has been reported from unicellular algae, slime mould, and gymnosperms. We have isolated the JcWRKY cDNA from an important biofuel crop Jatropha curcas growing in the wastelands of India. The JcWRKY gene has an ORF of 693 bp and encodes a 230 amino acids protein with estimated molecular mass of 25.25 kDa. JcWRKY shows close homology to FaWRKY1 and St-WRKY1. The JcWRKY contains seven potential phosphorylation sites, which might be involved in regulating its function. The transcript analysis revealed that the JcWRKY transcript gets upregulated in response to salinity, dehydration, salicylic acid (SA), methyl jasmonate (MeJa), and collar rot fungus Macrophomina. However, maximum expression is observed under SA, highlighting its role in enhancing systemic acquired resistance for disease tolerance. The JcWRKY recombinant protein showed binding to W-box of pathogenesis related-1 (PR-1) and iso1 (encoding isoamylase1) promoters. Overexpression of JcWRKY in Escherichia coli enhanced the growth of cells in NaCl, KCl, mannitol, sorbitol, SA, and MeJa treatments, indicating that it protects and promotes growth under ionic, osmotic, and chemical stresses. The enhancement in growth can be due to the regulation of stress responsive genes. Therefore, it can be used as an important gene for enhancing abiotic and biotic resistance in plants and to facilitate faster growth of E. coli cells under stress conditions for efficient expression.

Genomic Tools in Cowpea Breeding Programs: Status and Perspectives

PubMed Central

Boukar, Ousmane; Fatokun, Christian A.; Huynh, Bao-Lam; Roberts, Philip A.; Close, Timothy J.

2016-01-01

Cowpea is one of the most important grain legumes in sub-Saharan Africa (SSA). It provides strong support to the livelihood of small-scale farmers through its contributions to their nutritional security, income generation and soil fertility enhancement. Worldwide about 6.5 million metric tons of cowpea are produced annually on about 14.5 million hectares. The low productivity of cowpea is attributable to numerous abiotic and biotic constraints. The abiotic stress factors comprise drought, low soil fertility, and heat while biotic constraints include insects, diseases, parasitic weeds, and nematodes. Cowpea farmers also have limited access to quality seeds of improved varieties for planting. Some progress has been made through conventional breeding at international and national research institutions in the last three decades. Cowpea improvement could also benefit from modern breeding methods based on molecular genetic tools. A number of advances in cowpea genetic linkage maps, and quantitative trait loci associated with some desirable traits such as resistance to Striga, Macrophomina, Fusarium wilt, bacterial blight, root-knot nematodes, aphids, and foliar thrips have been reported. An improved consensus genetic linkage map has been developed and used to identify QTLs of additional traits. In order to take advantage of these developments single nucleotide polymorphism (SNP) genotyping is being streamlined to establish an efficient workflow supported by genotyping support service (GSS)-client interactions. About 1100 SNPs mapped on the cowpea genome were converted by LGC Genomics to KASP assays. Several cowpea breeding programs have been exploiting these resources to implement molecular breeding, especially for MARS and MABC, to accelerate cowpea variety improvement. The combination of conventional breeding and molecular breeding strategies, with workflow managed through the CGIAR breeding management system (BMS), promises an increase in the number of improved varieties available to farmers, thereby boosting cowpea production and productivity in SSA. PMID:27375632

Comparison of the h-Index Scores Among Pathogens Identified as Emerging Hazards in North America.

PubMed

Cox, R; McIntyre, K M; Sanchez, J; Setzkorn, C; Baylis, M; Revie, C W

2016-02-01

Disease surveillance must assess the relative importance of pathogen hazards. Here, we use the Hirsch index (h-index) as a novel method to identify and rank infectious pathogens that are likely to be a hazard to human health in the North American region. This bibliometric index was developed to quantify an individual's scientific research output and was recently used as a proxy measure for pathogen impact. Analysis of more than 3000 infectious organisms indicated that 651 were human pathogen species that had been recorded in the North American region. The h-index of these pathogens ranged from 0 to 584. The h-index of emerging pathogens was greater than non-emerging pathogens as was the h-index of frequently pathogenic pathogens when compared to non-pathogenic pathogens. As expected, the h-index of pathogens varied over time between 1960 and 2011. We discuss how the h-index can contribute to pathogen prioritization and as an indicator of pathogen emergence. © 2014 Blackwell Verlag GmbH.

Pathogen and host genotype differently affect pathogen fitness through their effects on different life-history stages.

PubMed

Bruns, Emily; Carson, Martin; May, Georgiana

2012-08-02

Adaptation of pathogens to their hosts depends critically on factors affecting pathogen reproductive rate. While pathogen reproduction is the end result of an intricate interaction between host and pathogen, the relative contributions of host and pathogen genotype to variation in pathogen life history within the host are not well understood. Untangling these contributions allows us to identify traits with sufficient genetic variation for selection to act and to identify mechanisms of coevolution between pathogens and their hosts. We investigated the effects of pathogen and host genotype on three life-history components of pathogen fitness; infection efficiency, latent period, and sporulation capacity, in the oat crown rust fungus, Puccinia coronata f.sp. avenae, as it infects oats (Avena sativa). We show that both pathogen and host genotype significantly affect total spore production but do so through their effects on different life-history stages. Pathogen genotype has the strongest effect on the early stage of infection efficiency, while host genotype most strongly affects the later life-history stages of latent period and sporulation capacity. In addition, host genotype affected the relationship between pathogen density and the later life-history traits of latent period and sporulation capacity. We did not find evidence of pathogen-by-host genotypic (GxG) interactions. Our results illustrate mechanisms by which variation in host populations will affect the evolution of pathogen life history. Results show that different pathogen life-history stages have the potential to respond differently to selection by host or pathogen genotype and suggest mechanisms of antagonistic coevolution. Pathogen populations may adapt to host genotypes through increased infection efficiency while their plant hosts may adapt by limiting the later stages of pathogen growth and spore production within the host.

Higher plant diversity promotes higher diversity of fungal pathogens, while it decreases pathogen infection per plant.

PubMed

Rottstock, Tanja; Joshi, Jasmin; Kummer, Volker; Fischer, Markus

2014-07-01

Fungal plant pathogens are common in natural communities where they affect plant physiology, plant survival, and biomass production. Conversely, pathogen transmission and infection may be regulated by plant community characteristics such as plant species diversity and functional composition that favor pathogen diversity through increases in host diversity while simultaneously reducing pathogen infection via increased variability in host density and spatial heterogeneity. Therefore, a comprehensive understanding of multi-host multi-pathogen interactions is of high significance in the context of biodiversity-ecosystem functioning. We investigated the relationship between plant diversity and aboveground obligate parasitic fungal pathogen ("pathogens" hereafter) diversity and infection in grasslands of a long-term, large-scale, biodiversity experiment with varying plant species (1-60 species) and plant functional group diversity (1-4 groups). To estimate pathogen infection of the plant communities, we visually assessed pathogen-group presence (i.e., rusts, powdery mildews, downy mildews, smuts, and leaf-spot diseases) and overall infection levels (combining incidence and severity of each pathogen group) in 82 experimental plots on all aboveground organs of all plant species per plot during four surveys in 2006. Pathogen diversity, assessed as the cumulative number of pathogen groups on all plant species per plot, increased log-linearly with plant species diversity. However, pathogen incidence and severity, and hence overall infection, decreased with increasing plant species diversity. In addition, co-infection of plant individuals by two or more pathogen groups was less likely with increasing plant community diversity. We conclude that plant community diversity promotes pathogen-community diversity while at the same time reducing pathogen infection levels of plant individuals.

In Silico identification of pathogenic strains of Cronobacter from Biochemical data reveals association of inositol fermentation with pathogenicity.

PubMed

Hamby, Stephen E; Joseph, Susan; Forsythe, Stephen J; Chuzhanova, Nadia

2011-09-20

Cronobacter, formerly known as Enterobacter sakazakii, is a food-borne pathogen known to cause neonatal meningitis, septicaemia and death. Current diagnostic tests for identification of Cronobacter do not differentiate between species, necessitating time consuming 16S rDNA gene sequencing or multilocus sequence typing (MLST). The organism is ubiquitous, being found in the environment and in a wide range of foods, although there is variation in pathogenicity between Cronobacter isolates and between species. Therefore to be able to differentiate between the pathogenic and non-pathogenic strains is of interest to the food industry and regulators. Here we report the use of Expectation Maximization clustering to categorise 98 strains of Cronobacter as pathogenic or non-pathogenic based on biochemical test results from standard diagnostic test kits. Pathogenicity of a strain was postulated on the basis of either pathogenic symptoms associated with strain source or corresponding MLST sequence types, allowing the clusters to be labelled as containing either pathogenic or non-pathogenic strains. The resulting clusters gave good differentiation of strains into pathogenic and non-pathogenic groups, corresponding well to isolate source and MLST sequence type. The results also revealed a potential association between pathogenicity and inositol fermentation. An investigation of the genomes of Cronobacter sakazakii and C. turicensis revealed the gene for inositol monophosphatase is associated with putative virulence factors in pathogenic strains of Cronobacter. We demonstrated a computational approach allowing existing diagnostic kits to be used to identify pathogenic strains of Cronobacter. The resulting clusters correlated well with MLST sequence types and revealed new information about the pathogenicity of Cronobacter species.

Pathogen evolution and the immunological niche

PubMed Central

Cobey, Sarah

2014-01-01

Host immunity is a major driver of pathogen evolution and thus a major determinant of pathogen diversity. Explanations for pathogen diversity traditionally assume simple interactions between pathogens and the immune system, a view encapsulated by the susceptible–infected–recovered (SIR) model. However, there is growing evidence that the complexity of many host–pathogen interactions is dynamically important. This revised perspective requires broadening the definition of a pathogen's immunological phenotype, or what can be thought of as its immunological niche. After reviewing evidence that interactions between pathogens and host immunity drive much of pathogen evolution, I introduce the concept of a pathogen's immunological phenotype. Models that depart from the SIR paradigm demonstrate the utility of this perspective and show that it is particularly useful in understanding vaccine-induced evolution. This paper highlights questions in immunology, evolution, and ecology that must be answered to advance theories of pathogen diversity. PMID:25040161

Effect of pathogen concentrations on removal of Cryptosporidium and Giardia by conventional drinking water treatment.

PubMed

Assavasilavasukul, Prapakorn; Lau, Boris L T; Harrington, Gregory W; Hoffman, Rebecca M; Borchardt, Mark A

2008-05-01

The presence of waterborne enteric pathogens in municipal water supplies contributes risk to public health. To evaluate the removal of these pathogens in drinking water treatment processes, previous researchers have spiked raw waters with up to 10(6) pathogens/L in order to reliably detect the pathogens in treated water. These spike doses are 6-8 orders of magnitude higher than pathogen concentrations routinely observed in practice. In the present study, experiments were conducted with different sampling methods (i.e., grab versus continuous sampling) and initial pathogen concentrations ranging from 10(1) to 10(6) pathogens/L. Results showed that Cryptosporidium oocyst and Giardia cyst removal across conventional treatment were dependent on initial pathogen concentrations, with lower pathogen removals observed when lower initial pathogen spike doses were used. In addition, higher raw water turbidity appeared to result in higher log removal for both Cryptosporidium oocysts and Giardia cysts.

Compositions and methods for pathogen transport

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

El-Etr, Sahar; Farquar, George R.

This disclosure provides a method for transporting a pathogen under ambient conditions, by culturing the pathogen with an amoeba under conditions that favor the incorporation of the pathogen into a trophozoite, starving the amoeba until it encysts, then culturing under conditions that favor conversion of the amoeba back to a trophozoite. In one aspect, the conditions that favor incorporation of the pathogen into the cyst of the amoeba comprises contacting the pathogen with the amoeba in an iron rich environment. Virus and/or bacteria are pathogens that can be transported by the disclosed method. Amoeba that are useful in the disclosedmore » methods include, without limitation Acanthamoeba castellanii, Hartmannella vermiformis and Naegleria gruberi. The disclosed methods have utility in: transporting pathogens from military field hospitals and clinics to the laboratory; transporting pathogens from global satellite laboratories to clinical laboratories; long term storage of pathogens; enriching contaminated patient samples for pathogens of interest; biosurveillance and detection efforts.« less

Host–Multi-Pathogen Warfare: Pathogen Interactions in Co-infected Plants

PubMed Central

Abdullah, Araz S.; Moffat, Caroline S.; Lopez-Ruiz, Francisco J.; Gibberd, Mark R.; Hamblin, John; Zerihun, Ayalsew

2017-01-01

Studies of plant–pathogen interactions have historically focused on simple models of infection involving single host-single disease systems. However, plant infections often involve multiple species and/or genotypes and exhibit complexities not captured in single host-single disease systems. Here, we review recent insights into co-infection systems focusing on the dynamics of host-multi-pathogen interactions and the implications for host susceptibility/resistance. In co-infection systems, pathogen interactions include: (i) Competition, in which competing pathogens develop physical barriers or utilize toxins to exclude competitors from resource-dense niches; (ii) Cooperation, whereby pathogens beneficially interact, by providing mutual biochemical signals essential for pathogenesis, or through functional complementation via the exchange of resources necessary for survival; (iii) Coexistence, whereby pathogens can stably coexist through niche specialization. Furthermore, hosts are also able to, actively or passively, modulate niche competition through defense responses that target at least one pathogen. Typically, however, virulent pathogens subvert host defenses to facilitate infection, and responses elicited by one pathogen may be modified in the presence of another pathogen. Evidence also exists, albeit rare, of pathogens incorporating foreign genes that broaden niche adaptation and improve virulence. Throughout this review, we draw upon examples of co-infection systems from a range of pathogen types and identify outstanding questions for future innovation in disease control strategies. PMID:29118773

Assessment of pathogen levels in stream water column and bed sediment of Merced River Watershed in California

NASA Astrophysics Data System (ADS)

Vaddella, V. K.; Pandey, P.; Biswas, S.; Lewis, D. J.

2014-12-01

Mitigating pathogen levels in surface water is crucial for protecting public health. According to the U.S. Environmental Protection Agency (US EPA), approximately 480,000 km of rivers/streams are contaminated in the U.S., and a major cause of contamination is elevated levels of pathogen/pathogen indicator. Many of past studies showed considerably higher pathogen levels in sediment bed than that of the stream water column in rivers. In order to improve the understanding of pathogen levels in rivers in California, we carried out an extensive pathogen monitoring study in four different watersheds (Bear Creek, Ingalsbe, Maxwell, and Yosemite watersheds) of Merced River. Stream water and streambed sediment samples were collected from 17 locations. Pathogen levels (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) were enumerated in streambed sediment and water column. In addition, the impacts of heat stress on pathogen survival were assessed by inoculating pathogens into the water and sediment samples for understanding the pathogen survival in stream water column and streambed sediment. The pathogen enumeration (in water column and sediment bed) results indicated that the E. coli O157:H7, Salmonella spp. and Listeria monocytogenes levels were non-detectable in the water column and streambed sediment. The results of heat stress (50◦ C for 180 minutes) test indicated a pathogen decay at one order of magnitude (108 cfu/ml to 107 cfu/ml). Nonetheless, higher pathogen levels (1.13 × 107 cfu/ml) after the heat stress study showed potential pathogen survival at higher temperature. Preliminary results of this study would help in understanding the impacts of elevated temperature on pathogen in stream environment. Further studies are required to test the long-term heat-stress impacts on pathogen survival.

Daphnia magna shows reduced infection upon secondary exposure to a pathogen

PubMed Central

McTaggart, Seanna J.; Wilson, Philip J.; Little, Tom J.

2012-01-01

Previous pathogen exposure is an important predictor of the probability of becoming infected. This is deeply understood for vertebrate hosts, and increasingly so for invertebrate hosts. Here, we test if an initial pathogen exposure changes the infection outcome to a secondary pathogen exposure in the natural host–pathogen system Daphnia magna and Pasteuria ramosa. Hosts were initially exposed to an infective pathogen strain, a non-infective pathogen strain or a control. The same hosts underwent a second exposure, this time to an infective pathogen strain, either immediately after the initial encounter or 48 h later. We observed that an initial encounter with a pathogen always conferred protection against infection compared with controls. PMID:22875818

Daphnia magna shows reduced infection upon secondary exposure to a pathogen.

PubMed

McTaggart, Seanna J; Wilson, Philip J; Little, Tom J

2012-12-23

Previous pathogen exposure is an important predictor of the probability of becoming infected. This is deeply understood for vertebrate hosts, and increasingly so for invertebrate hosts. Here, we test if an initial pathogen exposure changes the infection outcome to a secondary pathogen exposure in the natural host-pathogen system Daphnia magna and Pasteuria ramosa. Hosts were initially exposed to an infective pathogen strain, a non-infective pathogen strain or a control. The same hosts underwent a second exposure, this time to an infective pathogen strain, either immediately after the initial encounter or 48 h later. We observed that an initial encounter with a pathogen always conferred protection against infection compared with controls.

Pathogen evolution under host avoidance plasticity.

PubMed

McLeod, David V; Day, Troy

2015-09-07

Host resistance consists of defences that limit pathogen burden, and can be classified as either adaptations targeting recovery from infection or those focused upon infection avoidance. Conventional theory treats avoidance as a fixed strategy which does not vary from one interaction to the next. However, there is increasing empirical evidence that many avoidance strategies are triggered by external stimuli, and thus should be treated as phenotypically plastic responses. Here, we consider the implications of avoidance plasticity for host-pathogen coevolution. We uncover a number of predictions challenging current theory. First, in the absence of pathogen trade-offs, plasticity can restrain pathogen evolution; moreover, the pathogen exploits conditions in which the host would otherwise invest less in resistance, causing resistance escalation. Second, when transmission trades off with pathogen-induced mortality, plasticity encourages avirulence, resulting in a superior fitness outcome for both host and pathogen. Third, plasticity ensures the sterilizing effect of pathogens has consequences for pathogen evolution. When pathogens castrate hosts, selection forces them to minimize mortality virulence; moreover, when transmission trades off with sterility alone, resistance plasticity is sufficient to prevent pathogens from evolving to fully castrate. © 2015 The Author(s).

Future research needs involving pathogens in groundwater

NASA Astrophysics Data System (ADS)

Bradford, Scott A.; Harvey, Ronald W.

2017-06-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Future research needs involving pathogens in groundwater

USGS Publications Warehouse

Bradford, Scott A.; Harvey, Ronald W.

2017-01-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Centrality in the host-pathogen interactome is associated with pathogen fitness during infection.

PubMed

Crua Asensio, Núria; Muñoz Giner, Elisabet; de Groot, Natalia Sánchez; Torrent Burgas, Marc

2017-01-16

To perform their functions proteins must interact with each other, but how these interactions influence bacterial infection remains elusive. Here we demonstrate that connectivity in the host-pathogen interactome is directly related to pathogen fitness during infection. Using Y. pestis as a model organism, we show that the centrality-lethality rule holds for pathogen fitness during infection but only when the host-pathogen interactome is considered. Our results suggest that the importance of pathogen proteins during infection is directly related to their number of interactions with the host. We also show that pathogen proteins causing an extensive rewiring of the host interactome have a higher impact in pathogen fitness during infection. Hence, we conclude that hubs in the host-pathogen interactome should be explored as promising targets for antimicrobial drug design.

Centrality in the host-pathogen interactome is associated with pathogen fitness during infection

NASA Astrophysics Data System (ADS)

Crua Asensio, Núria; Muñoz Giner, Elisabet; de Groot, Natalia Sánchez; Torrent Burgas, Marc

2017-01-01

To perform their functions proteins must interact with each other, but how these interactions influence bacterial infection remains elusive. Here we demonstrate that connectivity in the host-pathogen interactome is directly related to pathogen fitness during infection. Using Y. pestis as a model organism, we show that the centrality-lethality rule holds for pathogen fitness during infection but only when the host-pathogen interactome is considered. Our results suggest that the importance of pathogen proteins during infection is directly related to their number of interactions with the host. We also show that pathogen proteins causing an extensive rewiring of the host interactome have a higher impact in pathogen fitness during infection. Hence, we conclude that hubs in the host-pathogen interactome should be explored as promising targets for antimicrobial drug design.

Weeds, as ancillary hosts, pose disproportionate risk for virulent pathogen transfer to crops.

PubMed

Linde, Celeste C; Smith, Leon M; Peakall, Rod

2016-05-12

The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typically have lower genetic diversity and thus small effective population sizes, but can potentially harbour large pathogen population sizes. On the other hand, hosts, such as weeds, which are genetically more diverse and thus have larger effective population sizes, usually harbour smaller pathogen population sizes. Large pathogen population sizes may lead to more opportunities for mutation and hence more diverse pathogens. Here we test the predictions that pathogen neutral genetic diversity will increase with large pathogen population sizes and host diversity, whereas diversity under selection will increase with host diversity. We assessed and compared the diversity of a fungal pathogen, Rhynchosporium commune, on weedy barley grass (which have a large effective population size) and cultivated barley (low genetic diversity) using microsatellites, effector locus nip1 diversity and pathogen aggressiveness in order to assess the importance of weeds in the evolution of the neutral and selected diversity of pathogens. The findings indicated that the large barley acreage and low host diversity maintains higher pathogen neutral genetic diversity and lower linkage disequilibrium, while the weed maintains more pathotypes and higher virulence diversity at nip1. Strong evidence for more pathogen migration from barley grass to barley suggests transmission of virulence from barley grass to barley is common. Pathogen census population size is a better predictor for neutral genetic diversity than host diversity. Despite maintaining a smaller pathogen census population size, barley grass acts as an important ancillary host to R. commune, harbouring highly virulent pathogen types capable of transmission to barley. Management of disease on crops must therefore include management of weedy ancillary hosts, which may harbour disproportionate supplies of virulent pathogen strains.

Pathogen evolution and the immunological niche.

PubMed

Cobey, Sarah

2014-07-01

Host immunity is a major driver of pathogen evolution and thus a major determinant of pathogen diversity. Explanations for pathogen diversity traditionally assume simple interactions between pathogens and the immune system, a view encapsulated by the susceptible-infected-recovered (SIR) model. However, there is growing evidence that the complexity of many host-pathogen interactions is dynamically important. This revised perspective requires broadening the definition of a pathogen's immunological phenotype, or what can be thought of as its immunological niche. After reviewing evidence that interactions between pathogens and host immunity drive much of pathogen evolution, I introduce the concept of a pathogen's immunological phenotype. Models that depart from the SIR paradigm demonstrate the utility of this perspective and show that it is particularly useful in understanding vaccine-induced evolution. This paper highlights questions in immunology, evolution, and ecology that must be answered to advance theories of pathogen diversity. © 2014 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals Inc. on behalf of The New York Academy of Sciences.

The race between infection and immunity - how do pathogens set the pace?

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

Ribiero, Ruy M

2009-01-01

Infection is often referred to as a race between pathogen and immune response. This metaphor suggests that slower growing pathogens should be more easily controlled. However, a growing body ofevidence shows that many chronic infections are caused by failure to control slow growing pathogens. The slow growth of pathogens appears to directly affect the kinetics of the immune response. Compared with the response to fast growing pathogens, the T cell response to slow pathogens is delayed in its initiation, lymphocyte expansion is slow and the response often fails to clear the pathogen, leading to chronic infection. Understanding the 'rules ofthemore » race' for slow growing pathogens has important implications for vaccine design and immune control of many chronic infections.« less

A Quantitative Prioritisation of Human and Domestic Animal Pathogens in Europe

PubMed Central

McIntyre, K. Marie; Setzkorn, Christian; Hepworth, Philip J.; Morand, Serge; Morse, Andrew P.; Baylis, Matthew

2014-01-01

Disease or pathogen risk prioritisations aid understanding of infectious agent impact within surveillance or mitigation and biosecurity work, but take significant development. Previous work has shown the H-(Hirsch-)index as an alternative proxy. We present a weighted risk analysis describing infectious pathogen impact for human health (human pathogens) and well-being (domestic animal pathogens) using an objective, evidence-based, repeatable approach; the H-index. This study established the highest H-index European pathogens. Commonalities amongst pathogens not included in previous surveillance or risk analyses were examined. Differences between host types (humans/animals/zoonotic) in pathogen H-indices were explored as a One Health impact indicator. Finally, the acceptability of the H-index proxy for animal pathogen impact was examined by comparison with other measures. 57 pathogens appeared solely in the top 100 highest H-indices (1) human or (2) animal pathogens list, and 43 occurred in both. Of human pathogens, 66 were zoonotic and 67 were emerging, compared to 67 and 57 for animals. There were statistically significant differences between H-indices for host types (humans, animal, zoonotic), and there was limited evidence that H-indices are a reasonable proxy for animal pathogen impact. This work addresses measures outlined by the European Commission to strengthen climate change resilience and biosecurity for infectious diseases. The results include a quantitative evaluation of infectious pathogen impact, and suggest greater impacts of human-only compared to zoonotic pathogens or scientific under-representation of zoonoses. The outputs separate high and low impact pathogens, and should be combined with other risk assessment methods relying on expert opinion or qualitative data for priority setting, or could be used to prioritise diseases for which formal risk assessments are not possible because of data gaps. PMID:25136810

AMP-activated Protein Kinase As a Target For Pathogens: Friends Or Foes?

PubMed

Moreira, Diana; Silvestre, Ricardo; Cordeiro-da-Silva, Anabela; Estaquier, Jérôme; Foretz, Marc; Viollet, Benoit

2016-01-01

Intracellular pathogens are known to manipulate host cell regulatory pathways to establish an optimal environment for their growth and survival. Pathogens employ active mechanisms to hijack host cell metabolism and acquire existing nutrient and energy store. The role of the cellular energy sensor AMP-activated protein kinase (AMPK) in the regulation of cellular energy homeostasis is well documented. Here, we highlight recent advances showing the importance of AMPK signaling in pathogen-host interactions. Pathogens interact with AMPK by a variety of mechanisms aimed at reprogramming host cell metabolism to their own benefit. Stimulation of AMPK activity provides an efficient process to rapidly adapt pathogen metabolism to the major nutritional changes often encountered during the different phases of infection. However, inhibition of AMPK is also used by pathogens to manipulate innate host response, indicating that AMPK appears relevant to restriction of pathogen infection. We also document the effects of pharmacological AMPK modulators on pathogen proliferation and survival. This review illustrates intricate pathogen-AMPK interactions that may be exploited to the development of novel anti-pathogen therapies.

AMP-activated protein kinase as a target for pathogens: friends or foes?

PubMed Central

Moreira, Diana; Silvestre, Ricardo; Cordeiro-Da-Silva, Anabela; Estaquier, Jérôme; Foretz, Marc; Viollet, Benoit

2016-01-01

Intracellular pathogens are known to manipulate host cell regulatory pathways to establish an optimal environment for their growth and survival. Pathogens employ active mechanisms to hijack host cell metabolism and acquire existing nutrient and energy store. The role of the cellular energy sensor AMP-activated protein kinase (AMPK) in the regulation of cellular energy homeostasis is well documented. Here, we highlight recent advances showing the importance of AMPK signaling in pathogen-host interactions. Pathogens interact with AMPK by a variety of mechanisms aimed at reprogramming host cell metabolism to their own benefit. Stimulation of AMPK activity provides an efficient process to rapidly adapt pathogen metabolism to the major nutritional changes often encountered during the different phases of infection. However, inhibition of AMPK is also used by pathogens to manipulate innate host response, indicating that AMPK appears relevant to restriction of pathogen infection. We also document the effects of pharmacological AMPK modulators on pathogen proliferation and survival. This review illustrates intricate pathogen-AMPK interactions that maybe exploited to the development of novel anti-pathogen therapies. PMID:25882224

[A pathogenesis study of tic disorder in children based on pathogen incubation theory].

PubMed

Zhou, Ya-bing; Wu, Min

2007-11-01

Pathogen incubation theory includes "no manifestation after infection" and "manifestation after incubation". Clinical data showed that the incidence and recurrence of tic disorders in children had a strong relevance to six exogenous factors. The pathogenesis is similar to the pathogenic mechanism based on incubation of pathogen theory, so we proposed a theory of "tic disorder induced by incubation of pathogen". Pathogenic wind can be classified into exterior wind and endogenous wind. Pathogenic wind is more apt to move, rise and migrate. The characteristics of pathogenic wind, especially easy mobility, determine the symptoms and signs of tic disorder, for pathogenic wind can be characterized by vibration and involuntary movement such as convulsion and tremor. If exogenous pathogenic wind moves into half-exterior and half-interior phase from the exterior, both the exterior and interior syndromes should be treated at the same time. We should regulate the function of the liver and the lung, expel pathogenic wind by dispersing the lung, and calm endogenous wind by removing obstruction in the collaterals and soothing the liver.

Plant growth-promoting potential of bacteria isolated from active volcano sites of Barren Island, India.

PubMed

Amaresan, N; Kumar, K; Sureshbabu, K; Madhuri, K

2014-02-01

To elucidate the biodiversity of plant growth-promoting (PGP) bacteria in active volcano sites of Barren Island, India, a total of 102 bacteria were isolated and screened for their multifunctional PGP properties. The results revealed that 21 isolates (20.6%) survived heat shock at 72°C and 11 (10.8%) isolates were able to grow exposed to 25% NaCl (w/v). In assaying for PGP properties, 59 (57.8%) isolates shown indole acetic acid (IAA) like substances production, 57 isolates (55.9%) produced siderophore and 34 (33.3%) solubilized inorganic phosphate qualitatively. Whereas in the production of extracellular enzymes, 42 isolates (41.2%) produced protease and amylase, 26 (25.5%) isolates produced lipase and 24 (23.5%) isolates produced cellulase. In antagonistic activity, 30 isolates (29.4%) were found antagonistic against Macrophomina sp., 20 isolates (19.6%) against Rhizoctonia solani and 15 isolates (14.7%) against Sclerotium rolfsii. The results based on 16 rRNA gene sequencing revealed that the PGP bacteria belonged to 22 different species comprising 13 genera. Based on multifunctional properties, nine isolates were further selected to determine the PGP in brinjal and chilli seeds. Of the bacteria tested, the isolate BAN87 showed increased root and shoot length of both the crops followed in plant growth promotion by BAN86 and BAN43. The outcome of this research proves plausible practical applicability of these PGPB for crop production in soils of saline and arid environments. The present research shows diverse plant growth-promoting (PGP) bacteria could be isolated from the active volcano site and suggests that volcano sites represent an ecological niche, which harbours a diverse and hitherto largely uncharacterized microbial population with yet unknown and untapped potential biotechnological applications, for example, plant growth promoters, as evidenced from this study. The outcome of this research may have a practical effect on crop production methodologies in saline and arid environment soils. © 2013 The Society for Applied Microbiology.

Conservation of Erwinia amylovora pathogenicity-relevant genes among Erwinia genomes.

PubMed

Borruso, Luigimaria; Salomone-Stagni, Marco; Polsinelli, Ivan; Schmitt, Armin Otto; Benini, Stefano

2017-12-01

The Erwinia genus comprises species that are plant pathogens, non-pathogen, epiphytes, and opportunistic human pathogens. Within the genus, Erwinia amylovora ranks among the top 10 plant pathogenic bacteria. It causes the fire blight disease and is a global threat to commercial apple and pear production. We analyzed the presence/absence of the E. amylovora genes reported to be important for pathogenicity towards Rosaceae within various Erwinia strains genomes. This simple bottom-up approach, allowed us to correlate the analyzed genes to pathogenicity, host specificity, and make useful considerations to drive targeted studies.

Pathogen recognition in the innate immune response.

PubMed

Kumar, Himanshu; Kawai, Taro; Akira, Shizuo

2009-04-28

Immunity against microbial pathogens primarily depends on the recognition of pathogen components by innate receptors expressed on immune and non-immune cells. Innate receptors are evolutionarily conserved germ-line-encoded proteins and include TLRs (Toll-like receptors), RLRs [RIG-I (retinoic acid-inducible gene-I)-like receptors] and NLRs (Nod-like receptors). These receptors recognize pathogens or pathogen-derived products in different cellular compartments, such as the plasma membrane, the endosomes or the cytoplasm, and induce the expression of cytokines, chemokines and co-stimulatory molecules to eliminate pathogens and instruct pathogen-specific adaptive immune responses. In the present review, we will discuss the recent progress in the study of pathogen recognition by TLRs, RLRs and NLRs and their signalling pathways.

Development of saliva-based exposure assays for detecting exposure to waterborne pathogens

EPA Pesticide Factsheets

Identifying which pathogens we are exposed to can be challenging because many types of pathogens can be found in water and many pathogens have similar symptoms. EPA scientists have developed a simple way to measure human exposure to waterborne pathogens.

Shared influence of pathogen and host genetics on a trade-off between latent period and spore production capacity in the wheat pathogen, Puccinia triticina.

PubMed

Pariaud, Bénédicte; Berg, Femke; Bosch, Frank; Powers, Stephen J; Kaltz, Oliver; Lannou, Christian

2013-02-01

Crop pathogens are notorious for their rapid adaptation to their host. We still know little about the evolution of their life cycles and whether there might be trade-offs between fitness components, limiting the evolutionary potential of these pathogens. In this study, we explored a trade-off between spore production capacity and latent period in Puccinia triticina, a fungal pathogen causing leaf rust on wheat. Using a simple multivariate (manova) technique, we showed that the covariance between the two traits is under shared control of host and pathogen, with contributions from host genotype (57%), pathogen genotype (18.4%) and genotype × genotype interactions (12.5%). We also found variation in sign and strength of genetic correlations for the pathogen, when measured on different host varieties. Our results suggest that these important pathogen life-history traits do not freely respond to directional selection and that precise evolutionary trajectories are contingent on the genetic identity of the interacting host and pathogen.

Sensitizing pathogens to antibiotics using the CRISPR-Cas system.

PubMed

Goren, Moran; Yosef, Ido; Qimron, Udi

2017-01-01

The extensive use of antibiotics over the last century has resulted in a significant artificial selection pressure for antibiotic-resistant pathogens to evolve. Various strategies to fight these pathogens have been introduced including new antibiotics, naturally-derived enzymes/peptides that specifically target pathogens and bacteriophages that lyse these pathogens. A new tool has recently been introduced in the fight against drug-resistant pathogens-the prokaryotic defense mechanism-clustered regularly interspaced short palindromic repeats-CRISPR associated (CRISPR-Cas) system. The CRISPR-Cas system acts as a nuclease that can be guided to cleave any target DNA, allowing sophisticated, yet feasible, manipulations of pathogens. Here, we review pioneering studies that use the CRISPR-Cas system to specifically edit bacterial populations, eliminate their resistance genes and combine these two strategies in order to produce an artificial selection pressure for antibiotic-sensitive pathogens. We suggest that intelligent design of this system, along with efficient delivery tools into pathogens, may significantly reduce the threat of antibiotic-resistant pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

Profile and Fate of Bacterial Pathogens in Sewage Treatment Plants Revealed by High-Throughput Metagenomic Approach.

PubMed

Li, Bing; Ju, Feng; Cai, Lin; Zhang, Tong

2015-09-01

The broad-spectrum profile of bacterial pathogens and their fate in sewage treatment plants (STPs) were investigated using high-throughput sequencing based metagenomic approach. This novel approach could provide a united platform to standardize bacterial pathogen detection and realize direct comparison among different samples. Totally, 113 bacterial pathogen species were detected in eight samples including influent, effluent, activated sludge (AS), biofilm, and anaerobic digestion sludge with the abundances ranging from 0.000095% to 4.89%. Among these 113 bacterial pathogens, 79 species were reported in STPs for the first time. Specially, compared to AS in bulk mixed liquor, more pathogen species and higher total abundance were detected in upper foaming layer of AS. This suggests that the foaming layer of AS might impose more threat to onsite workers and citizens in the surrounding areas of STPs because pathogens in foaming layer are easily transferred into air and cause possible infections. The high removal efficiency (98.0%) of total bacterial pathogens suggests that AS treatment process is effective to remove most bacterial pathogens. Remarkable similarities of bacterial pathogen compositions between influent and human gut indicated that bacterial pathogen profiles in influents could well reflect the average bacterial pathogen communities of urban resident guts within the STP catchment area.

Association and Host Selectivity in Multi-Host Pathogens

PubMed Central

Malpica, José M.; Sacristán, Soledad; Fraile, Aurora; García-Arenal, Fernando

2006-01-01

The distribution of multi-host pathogens over their host range conditions their population dynamics and structure. Also, host co-infection by different pathogens may have important consequences for the evolution of hosts and pathogens, and host-pathogen co-evolution. Hence it is of interest to know if the distribution of pathogens over their host range is random, or if there are associations between hosts and pathogens, or between pathogens sharing a host. To analyse these issues we propose indices for the observed patterns of host infection by pathogens, and for the observed patterns of co-infection, and tests to analyse if these patterns conform to randomness or reflect associations. Applying these tests to the prevalence of five plant viruses on 21 wild plant species evidenced host-virus associations: most hosts and viruses were selective for viruses and hosts, respectively. Interestingly, the more host-selective viruses were the more prevalent ones, suggesting that host specialisation is a successful strategy for multi-host pathogens. Analyses also showed that viruses tended to associate positively in co-infected hosts. The developed indices and tests provide the tools to analyse how strong and common are these associations among different groups of pathogens, which will help to understand and model the population biology of multi-host pathogens. PMID:17183670

Prediction of molecular mimicry candidates in human pathogenic bacteria.

PubMed

Doxey, Andrew C; McConkey, Brendan J

2013-08-15

Molecular mimicry of host proteins is a common strategy adopted by bacterial pathogens to interfere with and exploit host processes. Despite the availability of pathogen genomes, few studies have attempted to predict virulence-associated mimicry relationships directly from genomic sequences. Here, we analyzed the proteomes of 62 pathogenic and 66 non-pathogenic bacterial species, and screened for the top pathogen-specific or pathogen-enriched sequence similarities to human proteins. The screen identified approximately 100 potential mimicry relationships including well-characterized examples among the top-scoring hits (e.g., RalF, internalin, yopH, and others), with about 1/3 of predicted relationships supported by existing literature. Examination of homology to virulence factors, statistically enriched functions, and comparison with literature indicated that the detected mimics target key host structures (e.g., extracellular matrix, ECM) and pathways (e.g., cell adhesion, lipid metabolism, and immune signaling). The top-scoring and most widespread mimicry pattern detected among pathogens consisted of elevated sequence similarities to ECM proteins including collagens and leucine-rich repeat proteins. Unexpectedly, analysis of the pathogen counterparts of these proteins revealed that they have evolved independently in different species of bacterial pathogens from separate repeat amplifications. Thus, our analysis provides evidence for two classes of mimics: complex proteins such as enzymes that have been acquired by eukaryote-to-pathogen horizontal transfer, and simpler repeat proteins that have independently evolved to mimic the host ECM. Ultimately, computational detection of pathogen-specific and pathogen-enriched similarities to host proteins provides insights into potentially novel mimicry-mediated virulence mechanisms of pathogenic bacteria.

Prediction of molecular mimicry candidates in human pathogenic bacteria

PubMed Central

Doxey, Andrew C; McConkey, Brendan J

2013-01-01

Molecular mimicry of host proteins is a common strategy adopted by bacterial pathogens to interfere with and exploit host processes. Despite the availability of pathogen genomes, few studies have attempted to predict virulence-associated mimicry relationships directly from genomic sequences. Here, we analyzed the proteomes of 62 pathogenic and 66 non-pathogenic bacterial species, and screened for the top pathogen-specific or pathogen-enriched sequence similarities to human proteins. The screen identified approximately 100 potential mimicry relationships including well-characterized examples among the top-scoring hits (e.g., RalF, internalin, yopH, and others), with about 1/3 of predicted relationships supported by existing literature. Examination of homology to virulence factors, statistically enriched functions, and comparison with literature indicated that the detected mimics target key host structures (e.g., extracellular matrix, ECM) and pathways (e.g., cell adhesion, lipid metabolism, and immune signaling). The top-scoring and most widespread mimicry pattern detected among pathogens consisted of elevated sequence similarities to ECM proteins including collagens and leucine-rich repeat proteins. Unexpectedly, analysis of the pathogen counterparts of these proteins revealed that they have evolved independently in different species of bacterial pathogens from separate repeat amplifications. Thus, our analysis provides evidence for two classes of mimics: complex proteins such as enzymes that have been acquired by eukaryote-to-pathogen horizontal transfer, and simpler repeat proteins that have independently evolved to mimic the host ECM. Ultimately, computational detection of pathogen-specific and pathogen-enriched similarities to host proteins provides insights into potentially novel mimicry-mediated virulence mechanisms of pathogenic bacteria. PMID:23715053

Contamination of produce with human pathogens: sources and solutions

USDA-ARS?s Scientific Manuscript database

Outbreaks of foodborne illnesses associated with the presence of human pathogens have led to increased concern about the prevalence of pathogens in the environment and the vulnerability of fresh produce to contamination by these pathogens. As the FDA strives to mandate treatments to reduce pathogen...

Xylella genomics and bacterial pathogenicity to plants.

PubMed

Dow, J M; Daniels, M J

2000-12-01

Xylella fastidiosa, a pathogen of citrus, is the first plant pathogenic bacterium for which the complete genome sequence has been published. Inspection of the sequence reveals high relatedness to many genes of other pathogens, notably Xanthomonas campestris. Based on this, we suggest that Xylella possesses certain easily testable properties that contribute to pathogenicity. We also present some general considerations for deriving information on pathogenicity from bacterial genomics. Copyright 2000 John Wiley & Sons, Ltd.

Interaction of pathogens with host cholesterol metabolism.

PubMed

Sviridov, Dmitri; Bukrinsky, Michael

2014-10-01

Pathogens of different taxa, from prions to protozoa, target cellular cholesterol metabolism to advance their own development and to impair host immune responses, but also causing metabolic complications, for example, atherosclerosis. This review describes recent findings of how pathogens do it. A common theme in interaction between pathogens and host cholesterol metabolism is pathogens targeting lipid rafts of the host plasma membrane. Many intracellular pathogens use rafts as an entry gate, taking advantage of the endocytic machinery and high abundance of outward-looking molecules that can be used as receptors. At the same time, disruption of the rafts' functional capacity, achieved by the pathogens through a number of various means, impairs the ability of the host to generate immune response, thus helping pathogen to thrive. Pathogens cannot synthesize cholesterol, and salvaging host cholesterol helps pathogens build advanced cholesterol-containing membranes and assembly platforms. Impact on cholesterol metabolism is not limited to the infected cells; proteins and microRNAs secreted by infected cells affect lipid metabolism systemically. Given an essential role that host cholesterol metabolism plays in pathogen development, targeting this interaction may be a viable strategy to fight infections, as well as metabolic complications of the infections.

Risk factors for drug-resistant pathogens in immunocompetent patients with pneumonia: Evaluation of PES pathogens.

PubMed

Ishida, Tadashi; Ito, Akihiro; Washio, Yasuyoshi; Yamazaki, Akio; Noyama, Maki; Tokioka, Fumiaki; Arita, Machiko

2017-01-01

The new acronym, PES pathogens (Pseudomonas aeruginosa, Enterobacteriaceae extended-spectrum beta-lactamase-positive, and methicillin-resistant Staphylococcus aureus), was recently proposed to identify drug-resistant pathogens associated with community-acquired pneumonia. To evaluate the risk factors for antimicrobial-resistant pathogens in immunocompetent patients with pneumonia and to validate the role of PES pathogens. A retrospective analysis of a prospective observational study of immunocompetent patients with pneumonia between March 2009 and June 2015 was conducted. We clarified the risk factors for PES pathogens. Of the total 1559 patients, an etiological diagnosis was made in 705 (45.2%) patients. PES pathogens were identified in 51 (7.2%) patients, with 53 PES pathogens (P. aeruginosa, 34; ESBL-positive Enterobacteriaceae, 6; and MRSA, 13). Patients with PES pathogens had tendencies toward initial treatment failure, readmission within 30 days, and a prolonged hospital stay. Using multivariate analysis, female sex (adjusted odds ratio [AOR] 1.998, 95% confidence interval [CI] 1.047-3.810), admission within 90 days (AOR 2.827, 95% CI 1.250-6.397), poor performance status (AOR 2.380, 95% CI 1.047-5.413), and enteral feeding (AOR 5.808, 95% CI 1.813-18.613) were independent risk factors for infection with PES pathogens. The area under the receiver operating characteristics curve for the risk factors was 0.66 (95% CI 0.577-0.744). We believe the definition of PES pathogens is an appropriate description of drug-resistant pathogens associated with pneumonia in immunocompetent patients. The frequency of PES pathogens is quite low. However, recognition is critical because they can cause refractory pneumonia and different antimicrobial treatment is required. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Transport and fate of microbial pathogens in agricultural settings

USGS Publications Warehouse

Bradford, Scott A.; Morales, Veronica L.; Zhang, Wei; Harvey, Ronald W.; Packman, Aaron I.; Mohanram, Arvind; Welty, Claire

2013-01-01

An understanding of the transport and survival of microbial pathogens (pathogens hereafter) in agricultural settings is needed to assess the risk of pathogen contamination to water and food resources, and to develop control strategies and treatment options. However, many knowledge gaps still remain in predicting the fate and transport of pathogens in runoff water, and then through the shallow vadose zone and groundwater. A number of transport pathways, processes, factors, and mathematical models often are needed to describe pathogen fate in agricultural settings. The level of complexity is dramatically enhanced by soil heterogeneity, as well as by temporal variability in temperature, water inputs, and pathogen sources. There is substantial variability in pathogen migration pathways, leading to changes in the dominant processes that control pathogen transport over different spatial and temporal scales. For example, intense rainfall events can generate runoff and preferential flow that can rapidly transport pathogens. Pathogens that survive for extended periods of time have a greatly enhanced probability of remaining viable when subjected to such rapid-transport events. Conversely, in dry seasons, pathogen transport depends more strongly on retention at diverse environmental surfaces controlled by a multitude of coupled physical, chemical, and microbiological factors. These interactions are incompletely characterized, leading to a lack of consensus on the proper mathematical framework to model pathogen transport even at the column scale. In addition, little is known about how to quantify transport and survival parameters at the scale of agricultural fields or watersheds. This review summarizes current conceptual and quantitative models for pathogen transport and fate in agricultural settings over a wide range of spatial and temporal scales. The authors also discuss the benefits that can be realized by improved modeling, and potential treatments to mitigate the risk of waterborne disease transmission.

PathogenFinder--distinguishing friend from foe using bacterial whole genome sequence data.

PubMed

Cosentino, Salvatore; Voldby Larsen, Mette; Møller Aarestrup, Frank; Lund, Ole

2013-01-01

Although the majority of bacteria are harmless or even beneficial to their host, others are highly virulent and can cause serious diseases, and even death. Due to the constantly decreasing cost of high-throughput sequencing there are now many completely sequenced genomes available from both human pathogenic and innocuous strains. The data can be used to identify gene families that correlate with pathogenicity and to develop tools to predict the pathogenicity of newly sequenced strains, investigations that previously were mainly done by means of more expensive and time consuming experimental approaches. We describe PathogenFinder (http://cge.cbs.dtu.dk/services/PathogenFinder/), a web-server for the prediction of bacterial pathogenicity by analysing the input proteome, genome, or raw reads provided by the user. The method relies on groups of proteins, created without regard to their annotated function or known involvement in pathogenicity. The method has been built to work with all taxonomic groups of bacteria and using the entire training-set, achieved an accuracy of 88.6% on an independent test-set, by correctly classifying 398 out of 449 completely sequenced bacteria. The approach here proposed is not biased on sets of genes known to be associated with pathogenicity, thus the approach could aid the discovery of novel pathogenicity factors. Furthermore the pathogenicity prediction web-server could be used to isolate the potential pathogenic features of both known and unknown strains.

Predators indirectly control vector-borne disease: linking predator-prey and host-pathogen models.

PubMed

Moore, Sean M; Borer, Elizabeth T; Hosseini, Parviez R

2010-01-06

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of predators on vectored-pathogen dynamics, we developed a theoretical model that integrates predator-prey and host-pathogen theory. We used this model to determine whether predation can prevent pathogen persistence or alter the stability of host-pathogen dynamics. We found that, in the absence of predation, pathogen prevalence in the host increases with vector fecundity, whereas predation on the vector causes pathogen prevalence to decline, or even become extinct, with increasing vector fecundity. We also found that predation on a vector may drastically slow the initial spread of a pathogen. The predator can increase host abundance indirectly by reducing or eliminating infection in the host population. These results highlight the importance of studying interactions that, within the greater community, may alter our predictions when studying disease dynamics. From an applied perspective, these results also suggest situations where an introduced predator or the natural enemies of a vector may slow the rate of spread of an emerging vector-borne pathogen.

Genomic Evidence for the Evolution of Streptococcus equi: Host Restriction, Increased Virulence, and Genetic Exchange with Human Pathogens

PubMed Central

Paillot, Romain; Steward, Karen F.; Webb, Katy; Ainslie, Fern; Jourdan, Thibaud; Bason, Nathalie C.; Holroyd, Nancy E.; Mungall, Karen; Quail, Michael A.; Sanders, Mandy; Simmonds, Mark; Willey, David; Brooks, Karen; Aanensen, David M.; Spratt, Brian G.; Jolley, Keith A.; Maiden, Martin C. J.; Kehoe, Michael; Chanter, Neil; Bentley, Stephen D.; Robinson, Carl; Maskell, Duncan J.; Parkhill, Julian; Waller, Andrew S.

2009-01-01

The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A2 toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci. PMID:19325880

33 CFR 150.624 - What are the requirements for protecting personnel from blood-borne pathogens?

Code of Federal Regulations, 2010 CFR

2010-07-01

... protecting personnel from blood-borne pathogens? 150.624 Section 150.624 Navigation and Navigable Waters... Workplace Safety and Health Blood-Borne Pathogens § 150.624 What are the requirements for protecting personnel from blood-borne pathogens? Measures for protection from the dangers of blood-borne pathogens must...

33 CFR 150.624 - What are the requirements for protecting personnel from blood-borne pathogens?

Code of Federal Regulations, 2014 CFR

2014-07-01

... protecting personnel from blood-borne pathogens? 150.624 Section 150.624 Navigation and Navigable Waters... Workplace Safety and Health Blood-Borne Pathogens § 150.624 What are the requirements for protecting personnel from blood-borne pathogens? Measures for protection from the dangers of blood-borne pathogens must...

33 CFR 150.624 - What are the requirements for protecting personnel from blood-borne pathogens?

Code of Federal Regulations, 2012 CFR

2012-07-01

... protecting personnel from blood-borne pathogens? 150.624 Section 150.624 Navigation and Navigable Waters... Workplace Safety and Health Blood-Borne Pathogens § 150.624 What are the requirements for protecting personnel from blood-borne pathogens? Measures for protection from the dangers of blood-borne pathogens must...

33 CFR 150.624 - What are the requirements for protecting personnel from blood-borne pathogens?

Code of Federal Regulations, 2013 CFR

2013-07-01

... protecting personnel from blood-borne pathogens? 150.624 Section 150.624 Navigation and Navigable Waters... Workplace Safety and Health Blood-Borne Pathogens § 150.624 What are the requirements for protecting personnel from blood-borne pathogens? Measures for protection from the dangers of blood-borne pathogens must...

33 CFR 150.624 - What are the requirements for protecting personnel from blood-borne pathogens?

Code of Federal Regulations, 2011 CFR

2011-07-01

... protecting personnel from blood-borne pathogens? 150.624 Section 150.624 Navigation and Navigable Waters... Workplace Safety and Health Blood-Borne Pathogens § 150.624 What are the requirements for protecting personnel from blood-borne pathogens? Measures for protection from the dangers of blood-borne pathogens must...

Growth rate, transmission mode and virulence in human pathogens.

PubMed

Leggett, Helen C; Cornwallis, Charlie K; Buckling, Angus; West, Stuart A

2017-05-05

The harm that pathogens cause to hosts during infection, termed virulence, varies across species from negligible to a high likelihood of rapid death. Classic theory for the evolution of virulence is based on a trade-off between pathogen growth, transmission and host survival, which predicts that higher within-host growth causes increased transmission and higher virulence. However, using data from 61 human pathogens, we found the opposite correlation to the expected positive correlation between pathogen growth rate and virulence. We found that (i) slower growing pathogens are significantly more virulent than faster growing pathogens, (ii) inhaled pathogens and pathogens that infect via skin wounds are significantly more virulent than pathogens that are ingested, but (iii) there is no correlation between symptoms of infection that aid transmission (such as diarrhoea and coughing) and virulence. Overall, our results emphasize how virulence can be influenced by mechanistic life-history details, especially transmission mode, that determine how parasites infect and exploit their hosts.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Authors.

Immunomagnetic isolation of pathogen-containing phagosomes and apoptotic blebs from primary phagocytes.

PubMed

Steinhäuser, Christine; Dallenga, Tobias; Tchikov, Vladimir; Schaible, Ulrich E; Schütze, Stefan; Reiling, Norbert

2014-04-02

Macrophages and polymorphonuclear neutrophils are professional phagocytes essential in the initial host response against intracellular pathogens such as Mycobacterium tuberculosis. Phagocytosis is the first step in phagocyte-pathogen interaction, where the pathogen is engulfed into a membrane-enclosed compartment termed a phagosome. Subsequent effector functions of phagocytes result in killing and degradation of the pathogen by promoting phagosome maturation, and, terminally, phago-lysosome fusion. Intracellular pathogenic microbes use various strategies to avoid detection and elimination by phagocytes, including induction of apoptosis to escape host cells, thereby generating apoptotic blebs as shuttles to other cells for pathogens and antigens thereof. Hence, phagosomes represent compartments where host and pathogen become quite intimate, and apoptotic blebs are carrier bags of the pathogen's legacy. In order to investigate the molecular mechanisms underlying these interactions, both phagosomes and apoptotic blebs are required as purified subcellular fractions for subsequent analysis of their biochemical properties. Here, we describe a lipid-based procedure to magnetically label surfaces of either pathogenic mycobacteria or apoptotic blebs for purification by a strong magnetic field in a novel free-flow system. Copyright © 2014 John Wiley & Sons, Inc.

Occupancy Modeling for Improved Accuracy and Understanding of Pathogen Prevalence and Dynamics

PubMed Central

Colvin, Michael E.; Peterson, James T.; Kent, Michael L.; Schreck, Carl B.

2015-01-01

Most pathogen detection tests are imperfect, with a sensitivity < 100%, thereby resulting in the potential for a false negative, where a pathogen is present but not detected. False negatives in a sample inflate the number of non-detections, negatively biasing estimates of pathogen prevalence. Histological examination of tissues as a diagnostic test can be advantageous as multiple pathogens can be examined and providing important information on associated pathological changes to the host. However, it is usually less sensitive than molecular or microbiological tests for specific pathogens. Our study objectives were to 1) develop a hierarchical occupancy model to examine pathogen prevalence in spring Chinook salmon Oncorhynchus tshawytscha and their distribution among host tissues 2) use the model to estimate pathogen-specific test sensitivities and infection rates, and 3) illustrate the effect of using replicate within host sampling on sample sizes required to detect a pathogen. We examined histological sections of replicate tissue samples from spring Chinook salmon O. tshawytscha collected after spawning for common pathogens seen in this population: Apophallus/echinostome metacercariae, Parvicapsula minibicornis, Nanophyetus salmincola/ metacercariae, and Renibacterium salmoninarum. A hierarchical occupancy model was developed to estimate pathogen and tissue-specific test sensitivities and unbiased estimation of host- and organ-level infection rates. Model estimated sensitivities and host- and organ-level infections rates varied among pathogens and model estimated infection rate was higher than prevalence unadjusted for test sensitivity, confirming that prevalence unadjusted for test sensitivity was negatively biased. The modeling approach provided an analytical approach for using hierarchically structured pathogen detection data from lower sensitivity diagnostic tests, such as histology, to obtain unbiased pathogen prevalence estimates with associated uncertainties. Accounting for test sensitivity using within host replicate samples also required fewer individual fish to be sampled. This approach is useful for evaluating pathogen or microbe community dynamics when test sensitivity is <100%. PMID:25738709

Occupancy modeling for improved accuracy and understanding of pathogen prevalence and dynamics

USGS Publications Warehouse

Colvin, Michael E.; Peterson, James T.; Kent, Michael L.; Schreck, Carl B.

2015-01-01

Most pathogen detection tests are imperfect, with a sensitivity < 100%, thereby resulting in the potential for a false negative, where a pathogen is present but not detected. False negatives in a sample inflate the number of non-detections, negatively biasing estimates of pathogen prevalence. Histological examination of tissues as a diagnostic test can be advantageous as multiple pathogens can be examined and providing important information on associated pathological changes to the host. However, it is usually less sensitive than molecular or microbiological tests for specific pathogens. Our study objectives were to 1) develop a hierarchical occupancy model to examine pathogen prevalence in spring Chinook salmonOncorhynchus tshawytscha and their distribution among host tissues 2) use the model to estimate pathogen-specific test sensitivities and infection rates, and 3) illustrate the effect of using replicate within host sampling on sample sizes required to detect a pathogen. We examined histological sections of replicate tissue samples from spring Chinook salmon O. tshawytscha collected after spawning for common pathogens seen in this population:Apophallus/echinostome metacercariae, Parvicapsula minibicornis, Nanophyetus salmincola/metacercariae, and Renibacterium salmoninarum. A hierarchical occupancy model was developed to estimate pathogen and tissue-specific test sensitivities and unbiased estimation of host- and organ-level infection rates. Model estimated sensitivities and host- and organ-level infections rates varied among pathogens and model estimated infection rate was higher than prevalence unadjusted for test sensitivity, confirming that prevalence unadjusted for test sensitivity was negatively biased. The modeling approach provided an analytical approach for using hierarchically structured pathogen detection data from lower sensitivity diagnostic tests, such as histology, to obtain unbiased pathogen prevalence estimates with associated uncertainties. Accounting for test sensitivity using within host replicate samples also required fewer individual fish to be sampled. This approach is useful for evaluating pathogen or microbe community dynamics when test sensitivity is <100%.

Plant immunity: towards an integrated view of plant-pathogen interactions.

PubMed

Dodds, Peter N; Rathjen, John P

2010-08-01

Plants are engaged in a continuous co-evolutionary struggle for dominance with their pathogens. The outcomes of these interactions are of particular importance to human activities, as they can have dramatic effects on agricultural systems. The recent convergence of molecular studies of plant immunity and pathogen infection strategies is revealing an integrated picture of the plant-pathogen interaction from the perspective of both organisms. Plants have an amazing capacity to recognize pathogens through strategies involving both conserved and variable pathogen elicitors, and pathogens manipulate the defence response through secretion of virulence effector molecules. These insights suggest novel biotechnological approaches to crop protection.

Autophagy in plant pathogenic fungi.

PubMed

Liu, Xiao-Hong; Xu, Fei; Snyder, John Hugh; Shi, Huan-Bin; Lu, Jian-Ping; Lin, Fu-Cheng

2016-09-01

Autophagy is a conserved cellular process that degrades cytoplasmic constituents in vacuoles. Plant pathogenic fungi develop special infection structures and/or secrete a range of enzymes to invade their plant hosts. It has been demonstrated that monitoring autophagy processes can be extremely useful in visualizing the sequence of events leading to pathogenicity of plant pathogenic fungi. In this review, we introduce the molecular mechanisms involved in autophagy. In addition, we explore the relationship between autophagy and pathogenicity in plant pathogenic fungi. Finally, we discuss the various experimental strategies available for use in the study of autophagy in plant pathogenic fungi. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analyzing the Differences and Preferences of Pathogenic and Nonpathogenic Prokaryote Species

NASA Astrophysics Data System (ADS)

Nolen, L.; Duong, K.; Heim, N. A.; Payne, J.

2015-12-01

A limited amount of knowledge exists on the large-scale characteristics and differences of pathogenic species in comparison to all prokaryotes. Pathogenic species, like other prokaryotes, have attributes specific to their environment and lifestyles. However, because they have evolved to coexist inside their hosts, the conditions they occupy may be more limited than those of non-pathogenic species. In this study we investigate the possibility of divergent evolution between pathogenic and non-pathogenic species by examining differences that may have evolved as a result of the need to adapt to their host. For this research we analyzed data collected from over 1900 prokaryotic species and performed t-tests using R to quantify potential differences in preferences. To examine the possible divergences from nonpathogenic bacteria, we focused on three variables: cell biovolume, preferred environmental pH, and preferred environmental temperature. We also looked at differences between pathogenic and nonpathogenic species belonging to the same phylum. Our results suggest a strong divergence in abiotic preferences between the two groups, with pathogens occupying a much smaller range of temperatures and pHs than their non-pathogenic counterparts. However, while the median biovolume is different when comparing pathogens and nonpathogens, we cannot conclude that the mean values are significantly different from each other. In addition, we found evidence of convergent evolution, as the temperature and pH preferences of pathogenic bacteria species from different phlya all approach the same values. Pathogenic species do not, however, all approach the same biovolume values, suggesting that specific pH and temperature preferences are more characteristic of pathogens than certain biovolumes.

Vector-Borne Pathogen and Host Evolution in a Structured Immuno-Epidemiological System.

PubMed

Gulbudak, Hayriye; Cannataro, Vincent L; Tuncer, Necibe; Martcheva, Maia

2017-02-01

Vector-borne disease transmission is a common dissemination mode used by many pathogens to spread in a host population. Similar to directly transmitted diseases, the within-host interaction of a vector-borne pathogen and a host's immune system influences the pathogen's transmission potential between hosts via vectors. Yet there are few theoretical studies on virulence-transmission trade-offs and evolution in vector-borne pathogen-host systems. Here, we consider an immuno-epidemiological model that links the within-host dynamics to between-host circulation of a vector-borne disease. On the immunological scale, the model mimics antibody-pathogen dynamics for arbovirus diseases, such as Rift Valley fever and West Nile virus. The within-host dynamics govern transmission and host mortality and recovery in an age-since-infection structured host-vector-borne pathogen epidemic model. By considering multiple pathogen strains and multiple competing host populations differing in their within-host replication rate and immune response parameters, respectively, we derive evolutionary optimization principles for both pathogen and host. Invasion analysis shows that the [Formula: see text] maximization principle holds for the vector-borne pathogen. For the host, we prove that evolution favors minimizing case fatality ratio (CFR). These results are utilized to compute host and pathogen evolutionary trajectories and to determine how model parameters affect evolution outcomes. We find that increasing the vector inoculum size increases the pathogen [Formula: see text], but can either increase or decrease the pathogen virulence (the host CFR), suggesting that vector inoculum size can contribute to virulence of vector-borne diseases in distinct ways.

Climate change accelerates local disease extinction rates in a long-term wild host-pathogen association.

PubMed

Zhan, Jiasui; Ericson, Lars; Burdon, Jeremy J

2018-02-27

Pathogens are a significant component of all plant communities. In recent years, the potential for existing and emerging pathogens of agricultural crops to cause increased yield losses as a consequence of changing climatic patterns has raised considerable concern. In contrast, the response of naturally occurring, endemic pathogens to a warming climate has received little attention. Here, we report on the impact of a signature variable of global climate change - increasing temperature - on the long-term epidemiology of a natural host-pathogen association involving the rust pathogen Triphragmium ulmariae and its host plant Filipendula ulmaria. In a host-pathogen metapopulation involving approximately 230 host populations growing on an archipelago of islands in the Gulf of Bothnia we assessed changes in host population size and pathogen epidemiological measures over a 25-year period. We show how the incidence of disease and its severity declines over that period and most importantly demonstrate a positive association between a long-term trend of increasing extinction rates in individual pathogen populations of the metapopulation and increasing temperature. Our results are highly suggestive that changing climatic patterns, particularly mean monthly growing season (April-November) temperature, are markedly influencing the epidemiology of plant disease in this host-pathogen association. Given the important role plant pathogens have in shaping the structure of communities, changes in the epidemiology of pathogens have potentially far-reaching impacts on ecological and evolutionary processes. For these reasons, it is essential to increase understanding of pathogen epidemiology, its response to warming, and to invoke these responses in forecasts for the future. © 2018 John Wiley & Sons Ltd.

Tick-Pathogen Interactions and Vector Competence: Identification of Molecular Drivers for Tick-Borne Diseases

PubMed Central

de la Fuente, José; Antunes, Sandra; Bonnet, Sarah; Cabezas-Cruz, Alejandro; Domingos, Ana G.; Estrada-Peña, Agustín; Johnson, Nicholas; Kocan, Katherine M.; Mansfield, Karen L.; Nijhof, Ard M.; Papa, Anna; Rudenko, Nataliia; Villar, Margarita; Alberdi, Pilar; Torina, Alessandra; Ayllón, Nieves; Vancova, Marie; Golovchenko, Maryna; Grubhoffer, Libor; Caracappa, Santo; Fooks, Anthony R.; Gortazar, Christian; Rego, Ryan O. M.

2017-01-01

Ticks and the pathogens they transmit constitute a growing burden for human and animal health worldwide. Vector competence is a component of vectorial capacity and depends on genetic determinants affecting the ability of a vector to transmit a pathogen. These determinants affect traits such as tick-host-pathogen and susceptibility to pathogen infection. Therefore, the elucidation of the mechanisms involved in tick-pathogen interactions that affect vector competence is essential for the identification of molecular drivers for tick-borne diseases. In this review, we provide a comprehensive overview of tick-pathogen molecular interactions for bacteria, viruses, and protozoa affecting human and animal health. Additionally, the impact of tick microbiome on these interactions was considered. Results show that different pathogens evolved similar strategies such as manipulation of the immune response to infect vectors and facilitate multiplication and transmission. Furthermore, some of these strategies may be used by pathogens to infect both tick and mammalian hosts. Identification of interactions that promote tick survival, spread, and pathogen transmission provides the opportunity to disrupt these interactions and lead to a reduction in tick burden and the prevalence of tick-borne diseases. Targeting some of the similar mechanisms used by the pathogens for infection and transmission by ticks may assist in development of preventative strategies against multiple tick-borne diseases. PMID:28439499

Vacated niches, competitive release and the community ecology of pathogen eradication

PubMed Central

Lloyd-Smith, James O.

2013-01-01

A recurring theme in the epidemiological literature on disease eradication is that each pathogen occupies an ecological niche, and eradication of one pathogen leaves a vacant niche that favours the emergence of new pathogens to replace it. However, eminent figures have rejected this view unequivocally, stating that there is no basis to fear pathogen replacement and even that pathogen niches do not exist. After exploring the roots of this controversy, I propose resolutions to disputed issues by drawing on broader ecological theory, and advance a new consensus based on robust mechanistic principles. I argue that pathogen eradication (and cessation of vaccination) leads to a ‘vacated niche’, which could be re-invaded by the original pathogen if introduced. Consequences for other pathogens will vary, with the crucial mechanisms being competitive release, whereby the decline of one species allows its competitors to perform better, and evolutionary adaptation. Hence, eradication can cause a quantitative rise in the incidence of another infection, but whether this leads to emergence as an endemic pathogen depends on additional factors. I focus on the case study of human monkeypox and its rise following smallpox eradication, but also survey how these ideas apply to other pathogens and discuss implications for eradication policy. PMID:23798698

Using sediment budgets to investigate the pathogen flux through catchments.

PubMed

Whiteway, Tanya G; Laffan, Shawn W; Wasson, Robert J

2004-10-01

We demonstrate a materials budget approach to identify the main source areas and fluxes of pathogens through a landscape by using the flux of fine sediments as a proxyfor pathogens. Sediment budgets were created for three subcatchment tributaries of the Googong Reservoir in south-eastern New South Wales, Australia. Major inputs, sources, stores, and transport zones were estimated using sediment sampling, dam trap efficiency measures, and radionuclide tracing. Particle size analyses were used to quantify the fine-sediment component of the total sediment flux, from which the pathogen flux was inferred by considering the differences between the mobility and transportation of fine sediments and pathogens. Gullies were identified as important sources of fine sediment, and therefore of pathogens, with the pathogen risk compounded when cattle shelter in them during wet periods. The results also indicate that the degree of landscape modification influences both sediment and pathogen mobilization. Farm dams, swampy meadows and glades along drainage paths lower the flux of fine sediment, and therefore pathogens, in this landscape during low-flow periods. However, high-rainfall and high-flow events are likely to transport most of the fine sediment, and therefore pathogen, flux from the Googong landscape to the reservoir. Materials budgets are a repeatable and comparatively low-cost method for investigating the pathogen flux through a landscape.

Epigenetic regulation of development and pathogenesis in fungal plant pathogens.

PubMed

Dubey, Akanksha; Jeon, Junhyun

2017-08-01

Evidently, epigenetics is at forefront in explaining the mechanisms underlying the success of human pathogens and in the identification of pathogen-induced modifications within host plants. However, there is a lack of studies highlighting the role of epigenetics in the modulation of the growth and pathogenicity of fungal plant pathogens. In this review, we attempt to highlight and discuss the role of epigenetics in the regulation of the growth and pathogenicity of fungal phytopathogens using Magnaporthe oryzae, a devastating fungal plant pathogen, as a model system. With the perspective of wide application in the understanding of the development, pathogenesis and control of other fungal pathogens, we attempt to provide a synthesized view of the epigenetic studies conducted on M. oryzae to date. First, we discuss the mechanisms of epigenetic modifications in M. oryzae and their impact on fungal development and pathogenicity. Second, we highlight the unexplored epigenetic mechanisms and areas of research that should be considered in the near future to construct a holistic view of epigenetic functioning in M. oryzae and other fungal plant pathogens. Importantly, the development of a complete understanding of the modulation of epigenetic regulation in fungal pathogens can help in the identification of target points to combat fungal pathogenesis. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Potential effects of mixed infections in ticks on transmission dynamics of pathogens: comparative analysis of published records

USGS Publications Warehouse

Ginsberg, Howard S.

2008-01-01

Ticks are often infected with more than one pathogen, and several field surveys have documented nonrandom levels of coinfection. Levels of coinfection by pathogens in four tick species were analyzed using published infection data. Coinfection patterns of pathogens in field-collected ticks include numerous cases of higher or lower levels of coinfection than would be expected due to chance alone, but the vast majority of these cases can be explained on the basis of vertebrate host associations of the pathogens, without invoking interactions between pathogens within ticks. Nevertheless, some studies have demonstrated antagonistic interactions, and some have suggested potential mutualisms, between pathogens in ticks. Negative or positive interactions between pathogens within ticks can affect pathogen prevalence, and thus transmission patterns. Probabilistic projections suggest that the effect on transmission depends on initial conditions. When the number of tick bites is relatively low (e.g., for ticks biting humans) changes in prevalence in ticks are predicted to have a commensurate effects on pathogen transmission. In contrast, when the number of tick bites is high (e.g., for wild animal hosts) changes in pathogen prevalence in ticks have relatively little effect on levels of transmission to reservoir hosts, and thus on natural transmission cycles.

Phytohormone mediation of interactions between herbivores and plant pathogens.

PubMed

Lazebnik, Jenny; Frago, Enric; Dicke, Marcel; van Loon, Joop J A

2014-07-01

Induced plant defenses against either pathogens or herbivore attackers are regulated by phytohormones. These phytohormones are increasingly recognized as important mediators of interactions between organisms associated with plants. In this review, we discuss the role of plant defense hormones in sequential tri-partite interactions among plants, pathogenic microbes, and herbivorous insects, based on the most recent literature. We discuss the importance of pathogen trophic strategy in the interaction with herbivores that exhibit different feeding modes. Plant resistance mechanisms also affect plant quality in future interactions with attackers. We discuss exemplary evidence for the hypotheses that (i) biotrophic pathogens can facilitate chewing herbivores, unless plants exhibit effector-triggered immunity, but (ii) facilitate or inhibit phloem feeders. (iii) Necrotrophic pathogens, on the other hand, can inhibit both phloem feeders and chewers. We also propose herbivore feeding mode as predictor of effects on pathogens of different trophic strategies, providing evidence for the hypotheses that (iv) phloem feeders inhibit pathogen attack by increasing SA induction, whereas (v) chewing herbivores tend not to affect necrotrophic pathogens, while they may either inhibit or facilitate biotrophic pathogens. Putting these hypotheses to the test will increase our understanding of phytohormonal regulation of plant defense to sequential attack by plant pathogens and insect herbivores. This will provide valuable insight into plant-mediated ecological interactions among members of the plant-associated community.

Inhibition of gold nanoparticles (AuNPs) on pathogenic biofilm formation and invasion to host cells.

PubMed

Yu, Qilin; Li, Jianrong; Zhang, Yueqi; Wang, Yufan; Liu, Lu; Li, Mingchun

2016-05-25

Owing to the growing infectious diseases caused by eukaryotic and prokaryotic pathogens, it is urgent to develop novel antimicrobial agents against clinical pathogenic infections. Biofilm formation and invasion into the host cells are vital processes during pathogenic colonization and infection. In this study, we tested the inhibitory effect of Au nanoparticles (AuNPs) on pathogenic growth, biofilm formation and invasion. Interestingly, although the synthesized AuNPs had no significant toxicity to the tested pathogens, Candida albicans and Pseudomonas aeruginosa, the nanoparticles strongly inhibited pathogenic biofilm formation and invasion to dental pulp stem cells (DPSCs). Further investigations revealed that AuNPs abundantly bound to the pathogen cells, which likely contributed to their inhibitory effect on biofilm formation and invasion. Moreover, treatment of AuNPs led to activation of immune response-related genes in DPSCs, which may enhance the activity of host immune system against the pathogens. Zeta potential analysis and polyethylene glycol (PEG)/polyethyleneimine (PEI) coating tests further showed that the interaction between pathogen cells and AuNPs is associated with electrostatic attractions. Our findings shed novel light on the application of nanomaterials in fighting against clinical pathogens, and imply that the traditional growth inhibition test is not the only way to evaluate the drug effect during the screening of antimicrobial agents.

Development of a qualitative pathogen risk-assessment methodology for municipal-sludge landfilling

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

Not Available

1988-04-01

This report addresses potential risks from microbiological pathogens present in municipal sludge disposal in landfills. Municipal sludges contain a wide variety of bacteria, viruses, protozoa, helminths, and fungi. Survival characteristics of pathogens are critical factors in assessing the risks associated with potential transport of microorganisms from the sludge-soil matrix to the ground-water environment of landfills. Various models are discussed for predicting microbial die-off. The order of persistence in the environment from longest to shortest survival time appears to be helminth eggs > viruses > bacteria > protozoan cysts. Whether or not a pathogen reaches ground-water and is transported to drinking-watermore » wells depends on a number of factors, including initial concentration of the pathogen, survival of the pathogen, number of pathogens that reach the sludge-soil interface, degree of removal through the unsaturated and saturated-soil zones, and the hydraulic gradient. The degree to which each of these factors will influence the probability of pathogens entering ground-water cannot be determined precisely. Information on the fate of pathogens at existing landfills is sorely lacking. Additional laboratory and field studies are needed to determine the degree of pathogen leaching, survival and transport in ground-water in order to estimate potential risks from pathogens at sludge landfills with reasonable validity.« less

Enzyme-driven metabolomic screening: a proof-of-principle method for discovery of plant defence compounds targeted by pathogens.

PubMed

Carere, Jason; Colgrave, Michelle L; Stiller, Jiri; Liu, Chunji; Manners, John M; Kazan, Kemal; Gardiner, Donald M

2016-11-01

Plants produce a variety of secondary metabolites to defend themselves from pathogen attack, while pathogens have evolved to overcome plant defences by producing enzymes that degrade or modify these defence compounds. However, many compounds targeted by pathogen enzymes currently remain enigmatic. Identifying host compounds targeted by pathogen enzymes would enable us to understand the potential importance of such compounds in plant defence and modify them to make them insensitive to pathogen enzymes. Here, a proof of concept metabolomics-based method was developed to discover plant defence compounds modified by pathogens using two pathogen enzymes with known targets in wheat and tomato. Plant extracts treated with purified pathogen enzymes were subjected to LC-MS, and the relative abundance of metabolites before and after treatment were comparatively analysed. Using two enzymes from different pathogens the in planta targets could be found by combining relatively simple enzymology with the power of untargeted metabolomics. Key to the method is dataset simplification based on natural isotope occurrence and statistical filtering, which can be scripted. The method presented here will aid in our understanding of plant-pathogen interactions and may lead to the development of new plant protection strategies. © 2016 CSIRO. New Phytologist © 2016 New Phytologist Trust.

AMPK in Pathogens.

PubMed

Mesquita, Inês; Moreira, Diana; Sampaio-Marques, Belém; Laforge, Mireille; Cordeiro-da-Silva, Anabela; Ludovico, Paula; Estaquier, Jérôme; Silvestre, Ricardo

2016-01-01

During host-pathogen interactions, a complex web of events is crucial for the outcome of infection. Pathogen recognition triggers powerful cellular signaling events that is translated into the induction and maintenance of innate and adaptive host immunity against infection. In opposition, pathogens employ active mechanisms to manipulate host cell regulatory pathways toward their proliferation and survival. Among these, subversion of host cell energy metabolism by pathogens is currently recognized to play an important role in microbial growth and persistence. Extensive studies have documented the role of AMP-activated protein kinase (AMPK) signaling, a central cellular hub involved in the regulation of energy homeostasis, in host-pathogen interactions. Here, we highlight the most recent advances detailing how pathogens hijack cellular metabolism by suppressing or increasing the activity of the host energy sensor AMPK. We also address the role of lower eukaryote AMPK orthologues in the adaptive process to the host microenvironment and their contribution for pathogen survival, differentiation, and growth. Finally, we review the effects of pharmacological or genetic AMPK modulation on pathogen growth and persistence.

The trans-kingdom identification of negative regulators of pathogen hypervirulence.

PubMed

Brown, Neil A; Urban, Martin; Hammond-Kosack, Kim E

2016-01-01

Modern society and global ecosystems are increasingly under threat from pathogens, which cause a plethora of human, animal, invertebrate and plant diseases. Of increasing concern is the trans-kingdom tendency for increased pathogen virulence that is beginning to emerge in natural, clinical and agricultural settings. The study of pathogenicity has revealed multiple examples of convergently evolved virulence mechanisms. Originally described as rare, but increasingly common, are interactions where a single gene deletion in a pathogenic species causes hypervirulence. This review utilised the pathogen-host interaction database (www.PHI-base.org) to identify 112 hypervirulent mutations from 37 pathogen species, and subsequently interrogates the trans-kingdom, conserved, molecular, biochemical and cellular themes that cause hypervirulence. This study investigates 22 animal and 15 plant pathogens including 17 bacterial and 17 fungal species. Finally, the evolutionary significance and trans-kingdom requirement for negative regulators of hypervirulence and the implication of pathogen hypervirulence and emerging infectious diseases on society are discussed. © FEMS 2015.

Enteric Pathogens Associated with Childhood Diarrhea in Tripoli-Libya

PubMed Central

Rahouma, Amal; Klena, John D.; Krema, Zaineb; Abobker, Abdalwahed A.; Treesh, Khalid; Franka, Ezzedin; Abusnena, Omar; Shaheen, Hind I.; El Mohammady, Hanan; Abudher, Abdulhafid; Ghenghesh, Khalifa Sifaw

2011-01-01

Stool samples from children < 5 years of age with diarrhea (N = 239) were examined for enteric pathogens using a combination of culture, enzyme-immunoassay, and polymerase chain reaction methods. Pathogens were detected in 122 (51%) stool samples; single pathogens were detected in 37.2% and co-pathogens in 13.8% of samples. Norovirus, rotavirus, and diarrheagenic Escherichia coli (DEC) were the most frequently detected pathogens (15.5%, 13.4%, and 11.2%, respectively); Salmonella, adenovirus, and Aeromonas were detected less frequently (7.9%, 7.1%, and 4.2%). The most commonly detected DEC was enteroaggregative E. coli (5.4%). Resistance to ≥ 3 antimicrobials was observed in 60% (18/30) of the bacterial pathogens. Salmonella resistance to ciprofloxacin (63.1%) has become a concern. Enteric viral pathogens were the most significant causative agents of childhood diarrhea in Tripoli. Bacterial pathogens were also important contributors to pediatric diarrhea. The emergence of ciprofloxacin-resistant Salmonella represents a serious health problem that must be addressed by Libyan health authorities PMID:21633024

Evolution and genome architecture in fungal plant pathogens.

PubMed

Möller, Mareike; Stukenbrock, Eva H

2017-12-01

The fungal kingdom comprises some of the most devastating plant pathogens. Sequencing the genomes of fungal pathogens has shown a remarkable variability in genome size and architecture. Population genomic data enable us to understand the mechanisms and the history of changes in genome size and adaptive evolution in plant pathogens. Although transposable elements predominantly have negative effects on their host, fungal pathogens provide prominent examples of advantageous associations between rapidly evolving transposable elements and virulence genes that cause variation in virulence phenotypes. By providing homogeneous environments at large regional scales, managed ecosystems, such as modern agriculture, can be conducive for the rapid evolution and dispersal of pathogens. In this Review, we summarize key examples from fungal plant pathogen genomics and discuss evolutionary processes in pathogenic fungi in the context of molecular evolution, population genomics and agriculture.

Uncovering plant-pathogen crosstalk through apoplastic proteomic studies.

PubMed

Delaunois, Bertrand; Jeandet, Philippe; Clément, Christophe; Baillieul, Fabienne; Dorey, Stéphan; Cordelier, Sylvain

2014-01-01

Plant pathogens have evolved by developing different strategies to infect their host, which in turn have elaborated immune responses to counter the pathogen invasion. The apoplast, including the cell wall and extracellular space outside the plasma membrane, is one of the first compartments where pathogen-host interaction occurs. The plant cell wall is composed of a complex network of polysaccharides polymers and glycoproteins and serves as a natural physical barrier against pathogen invasion. The apoplastic fluid, circulating through the cell wall and intercellular spaces, provides a means for delivering molecules and facilitating intercellular communications. Some plant-pathogen interactions lead to plant cell wall degradation allowing pathogens to penetrate into the cells. In turn, the plant immune system recognizes microbial- or damage-associated molecular patterns (MAMPs or DAMPs) and initiates a set of basal immune responses, including the strengthening of the plant cell wall. The establishment of defense requires the regulation of a wide variety of proteins that are involved at different levels, from receptor perception of the pathogen via signaling mechanisms to the strengthening of the cell wall or degradation of the pathogen itself. A fine regulation of apoplastic proteins is therefore essential for rapid and effective pathogen perception and for maintaining cell wall integrity. This review aims to provide insight into analyses using proteomic approaches of the apoplast to highlight the modulation of the apoplastic protein patterns during pathogen infection and to unravel the key players involved in plant-pathogen interaction.

The Janus face of reactive oxygen species in resistance and susceptibility of plants to necrotrophic and biotrophic pathogens.

PubMed

Barna, B; Fodor, J; Harrach, B D; Pogány, M; Király, Z

2012-10-01

Plant pathogens can be divided into biotrophs and necrotrophs according to their different life styles; biotrophs prefer living, while necrotrophs prefer dead cells for nutritional purposes. Therefore tissue necrosis caused by reactive oxygen species (ROS) during pathogen infection increases host susceptibility to necrotrophic, but resistance to biotrophic pathogen. Consequently, elevation of antioxidant capacity of plants enhances their tolerance to development of necroses caused by necrotrophic pathogens. Plant hormones can strongly influence induction of ROS and antioxidants, thereby influencing susceptibility or resistance of plants to pathogens. Pathogen-induced ROS themselves are considered as signaling molecules. Generally, salicylic acid (SA) signaling induces defense against biotrophic pathogens, whereas jasmonic acid (JA) against necrotrophic pathogens. Furthermore pathogens can modify plant's defense signaling network for their own benefit by changing phytohormone homeostasis. On the other hand, ROS are harmful also to the pathogens, consequently they try to defend themselves by elevating antioxidant activity and secreting ROS scavengers in the infected tissue. The Janus face nature of ROS and plant cell death on biotrophic and on necrotrophic pathogens is also supported by the experiments with BAX inhibitor-1 and the mlo mutation of Mlo gene in barley. It was found that ROS and elevated plant antioxidant activity play an important role in systemic acquired resistance (SAR) and induced systemic resistance (ISR), as well as in mycorrhiza induced abiotic and biotic stress tolerance of plants. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Convergent Evolution of Pathogen Effectors toward Reactive Oxygen Species Signaling Networks in Plants.

PubMed

Jwa, Nam-Soo; Hwang, Byung Kook

2017-01-01

Microbial pathogens have evolved protein effectors to promote virulence and cause disease in host plants. Pathogen effectors delivered into plant cells suppress plant immune responses and modulate host metabolism to support the infection processes of pathogens. Reactive oxygen species (ROS) act as cellular signaling molecules to trigger plant immune responses, such as pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity. In this review, we discuss recent insights into the molecular functions of pathogen effectors that target multiple steps in the ROS signaling pathway in plants. The perception of PAMPs by pattern recognition receptors leads to the rapid and strong production of ROS through activation of NADPH oxidase Respiratory Burst Oxidase Homologs (RBOHs) as well as peroxidases. Specific pathogen effectors directly or indirectly interact with plant nucleotide-binding leucine-rich repeat receptors to induce ROS production and the hypersensitive response in plant cells. By contrast, virulent pathogens possess effectors capable of suppressing plant ROS bursts in different ways during infection. PAMP-triggered ROS bursts are suppressed by pathogen effectors that target mitogen-activated protein kinase cascades. Moreover, pathogen effectors target vesicle trafficking or metabolic priming, leading to the suppression of ROS production. Secreted pathogen effectors block the metabolic coenzyme NADP-malic enzyme, inhibiting the transfer of electrons to the NADPH oxidases (RBOHs) responsible for ROS generation. Collectively, pathogen effectors may have evolved to converge on a common host protein network to suppress the common plant immune system, including the ROS burst and cell death response in plants.

Reduced Set of Virulence Genes Allows High Accuracy Prediction of Bacterial Pathogenicity in Humans

PubMed Central

Iraola, Gregorio; Vazquez, Gustavo; Spangenberg, Lucía; Naya, Hugo

2012-01-01

Although there have been great advances in understanding bacterial pathogenesis, there is still a lack of integrative information about what makes a bacterium a human pathogen. The advent of high-throughput sequencing technologies has dramatically increased the amount of completed bacterial genomes, for both known human pathogenic and non-pathogenic strains; this information is now available to investigate genetic features that determine pathogenic phenotypes in bacteria. In this work we determined presence/absence patterns of different virulence-related genes among more than finished bacterial genomes from both human pathogenic and non-pathogenic strains, belonging to different taxonomic groups (i.e: Actinobacteria, Gammaproteobacteria, Firmicutes, etc.). An accuracy of 95% using a cross-fold validation scheme with in-fold feature selection is obtained when classifying human pathogens and non-pathogens. A reduced subset of highly informative genes () is presented and applied to an external validation set. The statistical model was implemented in the BacFier v1.0 software (freely available at ), that displays not only the prediction (pathogen/non-pathogen) and an associated probability for pathogenicity, but also the presence/absence vector for the analyzed genes, so it is possible to decipher the subset of virulence genes responsible for the classification on the analyzed genome. Furthermore, we discuss the biological relevance for bacterial pathogenesis of the core set of genes, corresponding to eight functional categories, all with evident and documented association with the phenotypes of interest. Also, we analyze which functional categories of virulence genes were more distinctive for pathogenicity in each taxonomic group, which seems to be a completely new kind of information and could lead to important evolutionary conclusions. PMID:22916122

Overcoming antibiotic resistance: Is siderophore Trojan horse conjugation an answer to evolving resistance in microbial pathogens?

PubMed

Dhusia, Kalyani; Bajpai, Archana; Ramteke, P W

2018-01-10

Comparative study of siderophore biosynthesis pathway in pathogens provides potential targets for antibiotics and host drug delivery as a part of computationally feasible microbial therapy. Iron acquisition using siderophore models is an essential and well established model in all microorganisms and microbial infections a known to cause great havoc to both plant and animal. Rapid development of antibiotic resistance in bacterial as well as fungal pathogens has drawn us at a verge where one has to get rid of the traditional way of obstructing pathogen using single or multiple antibiotic/chemical inhibitors or drugs. 'Trojan horse' strategy is an answer to this imperative call where antibiotic are by far sneaked into the pathogenic cell via the siderophore receptors at cell and outer membrane. This antibiotic once gets inside, generates a 'black hole' scenario within the opportunistic pathogens via iron scarcity. For pathogens whose siderophore are not compatible to smuggle drug due to their complex conformation and stiff valence bonds, there is another approach. By means of the siderophore biosynthesis pathways, potential targets for inhibition of these siderophores in pathogenic bacteria could be achieved and thus control pathogenic virulence. Method to design artificial exogenous siderophores for pathogens that would compete and succeed the battle of intake is also covered with this review. These manipulated siderophore would enter pathogenic cell like any other siderophore but will not disperse iron due to which iron inadequacy and hence pathogens control be accomplished. The aim of this review is to offer strategies to overcome the microbial infections/pathogens using siderophore. Copyright © 2017 Elsevier B.V. All rights reserved.

Biogeography of Human Infectious Diseases: A Global Historical Analysis

PubMed Central

Cashdan, Elizabeth

2014-01-01

Objectives Human pathogen richness and prevalence vary widely across the globe, yet we know little about whether global patterns found in other taxa also predict diversity in this important group of organisms. This study (a) assesses the relative importance of temperature, precipitation, habitat diversity, and population density on the global distributions of human pathogens and (b) evaluates the species-area predictions of island biogeography for human pathogen distributions on oceanic islands. Methods Historical data were used in order to minimize the influence of differential access to modern health care on pathogen prevalence. The database includes coded data (pathogen, environmental and cultural) for a worldwide sample of 186 non-industrial cultures, including 37 on islands. Prevalence levels for 10 pathogens were combined into a pathogen prevalence index, and OLS regression was used to model the environmental determinants of the prevalence index and number of pathogens. Results Pathogens (number and prevalence index) showed the expected latitudinal gradient, but predictors varied by latitude. Pathogens increased with temperature in high-latitude zones, while mean annual precipitation was a more important predictor in low-latitude zones. Other environmental factors associated with more pathogens included seasonal dry extremes, frost-free climates, and human population density outside the tropics. Islands showed the expected species-area relationship for all but the smallest islands, and the relationship was not mediated by habitat diversity. Although geographic distributions of free-living and parasitic taxa typically have different determinants, these data show that variables that influence the distribution of free-living organisms also shape the global distribution of human pathogens. Understanding the cause of these distributions is potentially important, since geographical variation in human pathogens has an important influence on global disparities in human welfare. PMID:25271730

Biogeography of human infectious diseases: a global historical analysis.

PubMed

Cashdan, Elizabeth

2014-01-01

Human pathogen richness and prevalence vary widely across the globe, yet we know little about whether global patterns found in other taxa also predict diversity in this important group of organisms. This study (a) assesses the relative importance of temperature, precipitation, habitat diversity, and population density on the global distributions of human pathogens and (b) evaluates the species-area predictions of island biogeography for human pathogen distributions on oceanic islands. Historical data were used in order to minimize the influence of differential access to modern health care on pathogen prevalence. The database includes coded data (pathogen, environmental and cultural) for a worldwide sample of 186 non-industrial cultures, including 37 on islands. Prevalence levels for 10 pathogens were combined into a pathogen prevalence index, and OLS regression was used to model the environmental determinants of the prevalence index and number of pathogens. Pathogens (number and prevalence index) showed the expected latitudinal gradient, but predictors varied by latitude. Pathogens increased with temperature in high-latitude zones, while mean annual precipitation was a more important predictor in low-latitude zones. Other environmental factors associated with more pathogens included seasonal dry extremes, frost-free climates, and human population density outside the tropics. Islands showed the expected species-area relationship for all but the smallest islands, and the relationship was not mediated by habitat diversity. Although geographic distributions of free-living and parasitic taxa typically have different determinants, these data show that variables that influence the distribution of free-living organisms also shape the global distribution of human pathogens. Understanding the cause of these distributions is potentially important, since geographical variation in human pathogens has an important influence on global disparities in human welfare.

Evaluation of minor pathogen intramammary infection, susceptibility parameters, and somatic cell counts on the development of new intramammary infections with major mastitis pathogens.

PubMed

Reyher, K K; Dohoo, I R; Scholl, D T; Keefe, G P

2012-07-01

Major mastitis pathogens such as Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium spp. and coagulase-negative staphylococci (CNS). The current literature comprises several studies (n=38) detailing analyses with conflicting results as to whether intramammary infections (IMI) with the minor pathogens decrease, increase, or have no effect on the risk of a quarter acquiring a new IMI (NIMI) with a major pathogen. The Canadian Bovine Mastitis Research Network has a large mastitis database derived from a 2-yr data collection on a national cohort of dairy farms, and data from this initiative were used to further investigate the effect of IMI with minor pathogens on the acquisition of new major pathogen infections (defined as a culture-positive quarter sample in a quarter that had been free of that major pathogen in previous samples in the sampling period). Longitudinal milk samplings of clinically normal udders taken over several 6-wk periods as well as samples from cows pre-dry-off and postcalving were used to this end (n=80,397 quarter milk samples). The effects of CNS and Corynebacterium spp. on the major mastitis pathogens Staph. aureus, Strep. uberis, Strep. dysgalactiae, and coliform bacteria (Escherichia coli and Klebsiella spp.) were investigated using risk ratio analyses and multilevel logistic regression models. Quarter-, cow- and herd-level susceptibility parameters were also evaluated and were able to account for the increased susceptibility that exists within herds, cows and quarters, removing it from estimates for the effects of the minor pathogens. Increased quarter-level susceptibility was associated with increased risk of major pathogen NIMI for all pathogens except the coliforms. Increased somatic cell count was consistently associated with elevated risk of new major pathogen infections, but this was assumed to be a result of low sensitivity of bacteriology to diagnose major pathogen NIMI expediently and accurately. The presence of CNS in the sample 2 samplings before the occurrence of a NIMI increased the odds of experiencing a Staph. aureus NIMI 2.0 times, making the presence of CNS a risk factor for acquiring a Staph. aureus NIMI. Even with this extensive data set, power was insufficient to make a definitive statement about the effect of minor pathogen IMI on the acquisition of major pathogen NIMI. Definitively answering questions of this nature are likely to require an extremely large data set dedicated particularly to minor pathogen presence and NIMI with major pathogens. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira

PubMed Central

Fouts, Derrick E.; Matthias, Michael A.; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E.; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L.; Haake, David A.; Haft, Daniel H.; Hartskeerl, Rudy; Ko, Albert I.; Levett, Paul N.; Matsunaga, James; Mechaly, Ariel E.; Monk, Jonathan M.; Nascimento, Ana L. T.; Nelson, Karen E.; Palsson, Bernhard; Peacock, Sharon J.; Picardeau, Mathieu; Ricaldi, Jessica N.; Thaipandungpanit, Janjira; Wunder, Elsio A.; Yang, X. Frank; Zhang, Jun-Jie; Vinetz, Joseph M.

2016-01-01

Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade’s refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic) vs. non-infectious Leptospira, this work provides new insights into the evolution of a genus of bacterial pathogens. This work will be a comprehensive roadmap for understanding leptospirosis pathogenesis. More generally, it provides new insights into mechanisms by which bacterial pathogens adapt to mammalian hosts. PMID:26890609

What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira.

PubMed

Fouts, Derrick E; Matthias, Michael A; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L; Haake, David A; Haft, Daniel H; Hartskeerl, Rudy; Ko, Albert I; Levett, Paul N; Matsunaga, James; Mechaly, Ariel E; Monk, Jonathan M; Nascimento, Ana L T; Nelson, Karen E; Palsson, Bernhard; Peacock, Sharon J; Picardeau, Mathieu; Ricaldi, Jessica N; Thaipandungpanit, Janjira; Wunder, Elsio A; Yang, X Frank; Zhang, Jun-Jie; Vinetz, Joseph M

2016-02-01

Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade's refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic) vs. non-infectious Leptospira, this work provides new insights into the evolution of a genus of bacterial pathogens. This work will be a comprehensive roadmap for understanding leptospirosis pathogenesis. More generally, it provides new insights into mechanisms by which bacterial pathogens adapt to mammalian hosts.

Examining the effect of intramammary infections with minor mastitis pathogens on the acquisition of new intramammary infections with major mastitis pathogens--a systematic review and meta-analysis.

PubMed

Reyher, K K; Haine, D; Dohoo, I R; Revie, C W

2012-11-01

Major mastitis pathogens such as Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Streptococcus dysgalactiae, and the coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium bovis and coagulase-negative staphylococci (CNS). The current literature contains several studies detailing analyses with conflicting results as to whether intramammary infection (IMI) with the minor pathogens decreases, increases, or has no effect on the risk of a quarter acquiring a new intramammary infection (NIMI) with a major pathogen. To investigate the available scientific evidence regarding the effect of IMI with minor pathogens on the acquisition of NIMI with major pathogens, a systematic review and meta-analysis were conducted. The total extant English- and French-language literature in electronic databases was searched and all publications cited by relevant papers were investigated. Results from 68 studies were extracted from 38 relevant papers. Random-effects models were used to investigate the effects of CNS and C. bovis on acquisition of new IMI with any of the major pathogens, as well as individually for the minor pathogens and Staph. aureus. Significant heterogeneity among studies exists, some of which could be accounted for by using meta-regression. Overall, observational studies showed no effect, whereas challenge studies showed strong and significant protective effects, specifically when major pathogens were introduced into the mammary gland via methods bypassing the teat end. Underlying risk can account for several unmeasured factors, and studies with higher underlying risk found more protective effects of minor pathogens. Larger doses of challenge organisms reduced the protective effect of minor pathogens, and studies with more stringent diagnostic criteria for pathogen IMI identified less protection. Smaller studies (those utilizing fewer than 40 cows) also showed a greater protective effect than larger studies. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A network approach to predict pathogenic genes for Fusarium graminearum.

PubMed

Liu, Xiaoping; Tang, Wei-Hua; Zhao, Xing-Ming; Chen, Luonan

2010-10-04

Fusarium graminearum is the pathogenic agent of Fusarium head blight (FHB), which is a destructive disease on wheat and barley, thereby causing huge economic loss and health problems to human by contaminating foods. Identifying pathogenic genes can shed light on pathogenesis underlying the interaction between F. graminearum and its plant host. However, it is difficult to detect pathogenic genes for this destructive pathogen by time-consuming and expensive molecular biological experiments in lab. On the other hand, computational methods provide an alternative way to solve this problem. Since pathogenesis is a complicated procedure that involves complex regulations and interactions, the molecular interaction network of F. graminearum can give clues to potential pathogenic genes. Furthermore, the gene expression data of F. graminearum before and after its invasion into plant host can also provide useful information. In this paper, a novel systems biology approach is presented to predict pathogenic genes of F. graminearum based on molecular interaction network and gene expression data. With a small number of known pathogenic genes as seed genes, a subnetwork that consists of potential pathogenic genes is identified from the protein-protein interaction network (PPIN) of F. graminearum, where the genes in the subnetwork are further required to be differentially expressed before and after the invasion of the pathogenic fungus. Therefore, the candidate genes in the subnetwork are expected to be involved in the same biological processes as seed genes, which imply that they are potential pathogenic genes. The prediction results show that most of the pathogenic genes of F. graminearum are enriched in two important signal transduction pathways, including G protein coupled receptor pathway and MAPK signaling pathway, which are known related to pathogenesis in other fungi. In addition, several pathogenic genes predicted by our method are verified in other pathogenic fungi, which demonstrate the effectiveness of the proposed method. The results presented in this paper not only can provide guidelines for future experimental verification, but also shed light on the pathogenesis of the destructive fungus F. graminearum.

Amino Acid Substitutions in PB1 of Avian Influenza Viruses Influence Pathogenicity and Transmissibility in Chickens

PubMed Central

Suzuki, Yasushi; Uchida, Yuko; Tanikawa, Taichiro; Maeda, Naohiro; Takemae, Nobuhiro

2014-01-01

ABSTRACT Amino acid substitutions were introduced into avian influenza virus PB1 in order to characterize the interaction between polymerase activity and pathogenicity. Previously, we used recombinant viruses containing the hemagglutinin (HA) and neuraminidase (NA) genes from the highly pathogenic avian influenza virus (HPAIV) H5N1 strain and other internal genes from two low-pathogenicity avian influenza viruses isolated from chicken and wild-bird hosts (LP and WB, respectively) to demonstrate that the pathogenicity of highly pathogenic avian influenza viruses (HPAIVs) of subtype H5N1 in chickens is regulated by the PB1 gene (Y. Uchida et al., J. Virol. 86:2686–2695, 2012, doi:http://dx.doi.org/10.1128/JVI.06374-11). In the present study, we introduced a C38Y substitution into WB PB1 and demonstrated that this substitution increased both polymerase activity in DF-1 cells in vitro and the pathogenicity of the recombinant viruses in chickens. The V14A substitution in LP PB1 reduced polymerase activity but did not affect pathogenicity in chickens. Interestingly, the V14A substitution reduced viral shedding and transmissibility. These studies demonstrate that increased polymerase activity correlates directly with enhanced pathogenicity, while decreased polymerase activity does not always correlate with pathogenicity and requires further analysis. IMPORTANCE We identified 2 novel amino acid substitutions in the avian influenza virus PB1 gene that affect the characteristics of highly pathogenic avian influenza viruses (HPAIVs) of the H5N1 subtype, such as viral replication and polymerase activity in vitro and pathogenicity and transmissibly in chickens. An amino acid substitution at residue 38 in PB1 directly affected pathogenicity in chickens and was associated with changes in polymerase activity in vitro. A substitution at residue 14 reduced polymerase activity in vitro, while its effects on pathogenicity and transmissibility depended on the constellation of internal genes. PMID:25031333

Ecosystem screening approach for pathogen-associated microorganisms affecting host disease.

PubMed

Galiana, Eric; Marais, Antoine; Mura, Catherine; Industri, Benoît; Arbiol, Gilles; Ponchet, Michel

2011-09-01

The microbial community in which a pathogen evolves is fundamental to disease outcome. Species interacting with a pathogen on the host surface shape the distribution, density, and genetic diversity of the inoculum, but the role of these species is rarely determined. The screening method developed here can be used to characterize pathogen-associated species affecting disease. This strategy involves three steps: (i) constitution of the microbial community, using the pathogen as a trap; (ii) community selection, using extracts from the pathogen as the sole nutrient source; and (iii) molecular identification and the screening of isolates focusing on their effects on the growth of the pathogen in vitro and host disease. This approach was applied to a soilborne plant pathogen, Phytophthora parasitica, structured in a biofilm, for screening the microbial community from the rhizosphere of Nicotiana tabacum (the host). Two of the characterized eukaryotes interfered with the oomycete cycle and may affect the host disease. A Vorticella species acted through a mutualistic interaction with P. parasitica, disseminating pathogenic material by leaving the biofilm. A Phoma species established an amensal interaction with P. parasitica, strongly suppressing disease by inhibiting P. parasitica germination. This screening method is appropriate for all nonobligate pathogens. It allows the definition of microbial species as promoters or suppressors of a disease for a given biotope. It should also help to identify important microbial relationships for ecology and evolution of pathogens.

Plant-Pathogen Effectors: Cellular Probes Interfering with Plant Defenses in Spatial and Temporal Manners

PubMed Central

Toruño, Tania Y.; Stergiopoulos, Ioannis; Coaker, Gitta

2017-01-01

Plants possess large arsenals of immune receptors capable of recognizing all pathogen classes. To cause disease, pathogenic organisms must be able to overcome physical barriers, suppress or evade immune perception, and derive nutrients from host tissues. Consequently, to facilitate some of these processes, pathogens secrete effector proteins that promote colonization. This review covers recent advances in the field of effector biology, focusing on conserved cellular processes targeted by effectors from diverse pathogens. The ability of effectors to facilitate pathogen entry into the host interior, suppress plant immune perception, and alter host physiology for pathogen benefit is discussed. Pathogens also deploy effectors in a spatial and temporal manner, depending on infection stage. Recent advances have also enhanced our understanding of effectors acting in specific plant organs and tissues. Effectors are excellent cellular probes that facilitate insight into biological processes as well as key points of vulnerability in plant immune signaling networks. PMID:27359369

Internalization of fresh produce by foodborne pathogens.

PubMed

Erickson, Marilyn C

2012-01-01

Recent studies addressing the internalization of fresh produce by foodborne pathogens arose in response to the growing number of recent and high profile outbreaks involving fresh produce. Because chemical sanitizing agents used during harvest and minimal processing are unlikely to reach enteric pathogens residing within plant tissue, it is imperative that paths for pathogen entry be recognized and minimized. Using both microscopy and microbial enumeration tools, enteric pathogens have been shown to enter plant tissues through both natural apertures (stomata, lateral junctions of roots, flowers) and damaged (wounds, cut surfaces) tissue. In studies revealing preharvest internalization via plant roots or leaf stomata, experimental conditions have primarily involved exposure of plants to high pathogen concentrations (≥ 6 log g⁻¹ soil or 6 log ml⁻¹ water), but those pathogens internalized appear to have short-term persistence. Postharvest internalization of pathogens via cut surfaces may be minimized by maintaining effective levels of sanitizing agents in waters during harvesting and minimal processing.

Assessment of bacterial pathogens in fresh rainwater and airborne particulate matter using Real-Time PCR

NASA Astrophysics Data System (ADS)

Kaushik, Rajni; Balasubramanian, Rajasekhar

2012-01-01

Bacterial pathogens in airborne particulate matter (PM) and in rainwater (RW) were detected using a robust and sensitive Real-Time PCR method. Both RW and PM were collected simultaneously in the tropical atmosphere of Singapore, which were then subjected to analysis for the presence of selected bacterial pathogens and potential pathogen of health concern ( Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Aeromonas hydrophila). These pathogens were found to be prevalent in both PM and RW samples with E. coli being the most prevalent potential pathogen in both types of samples. The temporal distribution of these pathogens in PM and RW was found to be similar to each other. Using the proposed microbiological technique, the atmospheric deposition (dry and wet deposition) of bacterial pathogens to lakes and reservoirs can be studied in view of growing concerns about the outbreak of waterborne diseases.

Intervention of Phytohormone Pathways by Pathogen Effectors[OPEN

PubMed Central

Kazan, Kemal; Lyons, Rebecca

2014-01-01

The constant struggle between plants and microbes has driven the evolution of multiple defense strategies in the host as well as offense strategies in the pathogen. To defend themselves from pathogen attack, plants often rely on elaborate signaling networks regulated by phytohormones. In turn, pathogens have adopted innovative strategies to manipulate phytohormone-regulated defenses. Tactics frequently employed by plant pathogens involve hijacking, evading, or disrupting hormone signaling pathways and/or crosstalk. As reviewed here, this is achieved mechanistically via pathogen-derived molecules known as effectors, which target phytohormone receptors, transcriptional activators and repressors, and other components of phytohormone signaling in the host plant. Herbivores and sap-sucking insects employ obligate pathogens such as viruses, phytoplasma, or symbiotic bacteria to intervene with phytohormone-regulated defenses. Overall, an improved understanding of phytohormone intervention strategies employed by pests and pathogens during their interactions with plants will ultimately lead to the development of new crop protection strategies. PMID:24920334

Interrelationships of food safety and plant pathology: the life cycle of human pathogens on plants.

PubMed

Barak, Jeri D; Schroeder, Brenda K

2012-01-01

Bacterial food-borne pathogens use plants as vectors between animal hosts, all the while following the life cycle script of plant-associated bacteria. Similar to phytobacteria, Salmonella, pathogenic Escherichia coli, and cross-domain pathogens have a foothold in agricultural production areas. The commonality of environmental contamination translates to contact with plants. Because of the chronic absence of kill steps against human pathogens for fresh produce, arrival on plants leads to persistence and the risk of human illness. Significant research progress is revealing mechanisms used by human pathogens to colonize plants and important biological interactions between and among bacteria in planta. These findings articulate the difficulty of eliminating or reducing the pathogen from plants. The plant itself may be an untapped key to clean produce. This review highlights the life of human pathogens outside an animal host, focusing on the role of plants, and illustrates areas that are ripe for future investigation.

Contamination of water resources by pathogenic bacteria

PubMed Central

2014-01-01

Water-borne pathogen contamination in water resources and related diseases are a major water quality concern throughout the world. Increasing interest in controlling water-borne pathogens in water resources evidenced by a large number of recent publications clearly attests to the need for studies that synthesize knowledge from multiple fields covering comparative aspects of pathogen contamination, and unify them in a single place in order to present and address the problem as a whole. Providing a broader perceptive of pathogen contamination in freshwater (rivers, lakes, reservoirs, groundwater) and saline water (estuaries and coastal waters) resources, this review paper attempts to develop the first comprehensive single source of existing information on pathogen contamination in multiple types of water resources. In addition, a comprehensive discussion describes the challenges associated with using indicator organisms. Potential impacts of water resources development on pathogen contamination as well as challenges that lie ahead for addressing pathogen contamination are also discussed. PMID:25006540

Insights From Natural Host-Parasite Interactions: The Drosophila Model

PubMed Central

Keebaugh, Erin S.; Schlenke, Todd A.

2013-01-01

Immune responses against opportunistic pathogens have been extensively studied in Drosophila, leading to a detailed map of the genetics behind innate immunity networks including the Toll, Imd, Jak-Stat, and JNK pathways. However, immune mechanisms of other organisms, particularly plants, have primarily been investigated using natural pathogens. It was the use of natural pathogens in plant research that revealed the plant R/Avr system, a specialized immune response derived from antagonistic coevolution between plant immune proteins and their natural pathogens’ virulence proteins. Thus, we recommend that researchers begin to use natural Drosophila pathogens to identify novel immune mechanisms that may have arisen through antagonistic coevolution with common natural pathogens. In this review, we address the benefits of using natural pathogens in research, describe the known natural pathogens of Drosophila, and discuss exciting prospects for future research on select natural pathogens of Drosophila. PMID:23764256

Transcriptome of an Armillaria root disease pathogen reveals candidate genes involved in host substrate utilization at the host­-pathogen interface

Treesearch

A. L. Ross-Davis; J. E. Stewart; J. W. Hanna; M.-S. Kim; B. J. Knaus; R. Cronn; H. Rai; B. A. Richardson; G. I. McDonald; N. B. Klopfenstein

2013-01-01

Armillaria species display diverse ecological roles ranging from beneficial saprobe to virulent pathogen. Armillaria solidipes (formerly A. ostoyae), a causal agent of Armillaria root disease, is a virulent primary pathogen with a broad host range of woody plants across the Northern Hemisphere. This white-rot pathogen grows between trees as rhizomorphs and attacks...

Promiscuous Pathogenicity Islands and Phylogeny of Pathogenic Streptomyces spp.

PubMed

Zhang, Yucheng; Bignell, Dawn R D; Zuo, Ran; Fan, Qiurong; Huguet-Tapia, Jose C; Ding, Yousong; Loria, Rosemary

2016-08-01

Approximately 10 Streptomyces species cause disease on underground plant structures. The most economically important of these is potato scab, and the most studied of these pathogens is Streptomyces scabiei (syn. S. scabies). The main pathogenicity determinant of scab-causing Streptomyces species is a nitrated diketopiperazine, known as thaxtomin A (ThxA). In the pathogenic species Streptomyces turgidiscabies, ThxA biosynthetic genes reside on a mobile pathogenicity island (PAI). However, the mobilization of PAIs in other Streptomyces species remains uncharacterized. Here, we investigated the mobilization of the PAI of S. scabiei 87-22. Based on whole genome sequences, we inferred the evolutionary relationships of pathogenic Streptomyces species and discovered that Streptomyces sp. strain 96-12, a novel pathogenic species isolated from potatoes in Egypt, was phylogenetically grouped with nonpathogenic species rather than with known pathogenic species. We also found that Streptomyces sp. strain 96-12 contains a PAI that is almost identical to the PAI in S. scabiei 87-22, despite significant differences in their genome sequences. This suggested direct or indirect in vivo mobilization of the PAI between S. scabiei and nonpathogenic Streptomyces species. To test whether the S. scabiei 87-22 PAI could, indeed, be mobilized, S. scabiei 87-22 deletion mutants containing antibiotic resistance markers in the PAI were mated with Streptomyces diastatochromogenes, a nonpathogenic species. The PAI of S. scabiei was site-specifically inserted into the aviX1 gene of S. diastatochromogenes and conferred pathogenicity in radish seedling assays. Our results demonstrated that S. scabiei, the earliest described Streptomyces pathogen, could be the source of a PAI responsible for the emergence of novel pathogenic species.

Pathogenic amoebae in power-plant cooling lakes. Final report

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

Tyndall, R.L.; Willaert, E.; Stevens, A.R.

1981-06-01

Cooling waters and associated algae and sediments from four northern and four southern/western electric power plants were tested for the presence of pathogenic amoebae. Unheated control waters and algae/sediments from four northern and five southern/western sites were also tested. When comparing results from the test versus control sites, a significantly higher proportion (P less than or equal to 0.05) of the samples from the test sites were positive for thermophilic amoeba, thermophilic Naegleria and pathogenic Naegleria. The difference in number of samples positive for thermophilic Naegleria between heated and unheated waters, however, was attributable predominantly to the northern waters andmore » algae/sediments. While two of four northern test sites yielded pathogenic Naegleria, seven of the eight isolates were obtained from one site. Seasonality effects relative to the isolation of the pathogen were also noted at this site. One pathogen was isolated from a southwestern test site. Pathogens were not isolated from any control sites. Some of the pathogenic isolates were analyzed serologically and classified as pathogenic Naegleria fowleri. Salinity, pH, conductivity, and bacteriological profiles did not obviously correlate with the presence or absence of pathogenic Naegleria. While thermal addition was significantly associated with the presence of thermophilic Naegleria (P less than or equal to 0.05), the data implicate other as yet undefined parameters associated with the presence of the pathogenic thermophile. Until further delineation of these parameters is effected, generalizations cannot be made concerning the effect of thermal impact on the growth of pathogenic amoeba in a particular cooling system.« less

Prevalences of pathogenic and non-pathogenic Vibrio parahaemolyticus in mollusks from the Spanish Mediterranean Coast

PubMed Central

Lopez-Joven, Carmen; de Blas, Ignacio; Furones, M. Dolores; Roque, Ana

2015-01-01

Vibrio parahaemolyticus is a well-recognized pathogen of humans. To better understand the ecology of the human-pathogenic variants of this bacterium in the environment, a study on the prevalence in bivalves of pathogenic variants (tlh+ and tdh+ and/or trh+) versus a non-pathogenic one (only tlh+ as species marker for V. parahaemolyticus), was performed in two bays in Catalonia, Spain. Environmental factors that might affect dynamics of both variants of V. parahaemolyticus were taken into account. The results showed that the global prevalence of total V. parahaemolyticus found in both bays was 14.2% (207/1459). It was, however, significantly dependent on sampling point, campaign (year) and bivalve species. Pathogenic variants of V. parahaemolyticus (tdh+ and/or trh+) were detected in 3.8% of the samples (56/1459), meaning that the proportion of bivalves who contained tlh gene were contaminated by pathogenic V. parahaemolyticus strains is 27.1% (56/207). Moreover, the presence of pathogenic V. parahaemolyticus (trh+) was significantly correlated with water salinity, thus the probability of finding pathogenic V. parahaemolyticus decreased 1.45 times with every salinity unit (ppt) increased. Additionally, data showed that V. parahaemolyticus could establish close associations with Ruditapes spp. (P-value < 0.001), which could enhance the transmission of illness to human by pathogenic variants, when clams were eaten raw or slightly cooked. This study provides information on the abundance, ecology and characteristics of total and human-pathogenic V. parahaemolyticus variants associated with bivalves cultured in the Spanish Mediterranean Coast. PMID:26284033

Convergent Evolution of Pathogen Effectors toward Reactive Oxygen Species Signaling Networks in Plants

PubMed Central

Jwa, Nam-Soo; Hwang, Byung Kook

2017-01-01

Microbial pathogens have evolved protein effectors to promote virulence and cause disease in host plants. Pathogen effectors delivered into plant cells suppress plant immune responses and modulate host metabolism to support the infection processes of pathogens. Reactive oxygen species (ROS) act as cellular signaling molecules to trigger plant immune responses, such as pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity. In this review, we discuss recent insights into the molecular functions of pathogen effectors that target multiple steps in the ROS signaling pathway in plants. The perception of PAMPs by pattern recognition receptors leads to the rapid and strong production of ROS through activation of NADPH oxidase Respiratory Burst Oxidase Homologs (RBOHs) as well as peroxidases. Specific pathogen effectors directly or indirectly interact with plant nucleotide-binding leucine-rich repeat receptors to induce ROS production and the hypersensitive response in plant cells. By contrast, virulent pathogens possess effectors capable of suppressing plant ROS bursts in different ways during infection. PAMP-triggered ROS bursts are suppressed by pathogen effectors that target mitogen-activated protein kinase cascades. Moreover, pathogen effectors target vesicle trafficking or metabolic priming, leading to the suppression of ROS production. Secreted pathogen effectors block the metabolic coenzyme NADP-malic enzyme, inhibiting the transfer of electrons to the NADPH oxidases (RBOHs) responsible for ROS generation. Collectively, pathogen effectors may have evolved to converge on a common host protein network to suppress the common plant immune system, including the ROS burst and cell death response in plants. PMID:29033963

A comparative hidden Markov model analysis pipeline identifies proteins characteristic of cereal-infecting fungi

PubMed Central

2013-01-01

Background Fungal pathogens cause devastating losses in economically important cereal crops by utilising pathogen proteins to infect host plants. Secreted pathogen proteins are referred to as effectors and have thus far been identified by selecting small, cysteine-rich peptides from the secretome despite increasing evidence that not all effectors share these attributes. Results We take advantage of the availability of sequenced fungal genomes and present an unbiased method for finding putative pathogen proteins and secreted effectors in a query genome via comparative hidden Markov model analyses followed by unsupervised protein clustering. Our method returns experimentally validated fungal effectors in Stagonospora nodorum and Fusarium oxysporum as well as the N-terminal Y/F/WxC-motif from the barley powdery mildew pathogen. Application to the cereal pathogen Fusarium graminearum reveals a secreted phosphorylcholine phosphatase that is characteristic of hemibiotrophic and necrotrophic cereal pathogens and shares an ancient selection process with bacterial plant pathogens. Three F. graminearum protein clusters are found with an enriched secretion signal. One of these putative effector clusters contains proteins that share a [SG]-P-C-[KR]-P sequence motif in the N-terminal and show features not commonly associated with fungal effectors. This motif is conserved in secreted pathogenic Fusarium proteins and a prime candidate for functional testing. Conclusions Our pipeline has successfully uncovered conservation patterns, putative effectors and motifs of fungal pathogens that would have been overlooked by existing approaches that identify effectors as small, secreted, cysteine-rich peptides. It can be applied to any pathogenic proteome data, such as microbial pathogen data of plants and other organisms. PMID:24252298

Social barriers to pathogen transmission in wild animal populations

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

Loehle, C.

Diseases and pathogens are receiving increasing recognition as sources of mortality in animal populations. Immune system strength is clearly important in fending off pathogen attack. Physical barriers to pathogen entry are also important. Various individual behaviors are efficacious in reducing contact with diseases and pests. This paper focuses on a fourth mode of defense: social barriers to transmission. Various social behaviors have pathogen transmission consequences. Selective pressures on these social behaviors may therefore exist. Effects on pathogen transmission of mating strategies, social avoidance, group size, group isolation, and other behaviors are explored. It is concluded that many of these behaviorsmore » may have been affected by selection pressures to reduce transmission of pathogens. 84 refs., 1 tab.« less

Foodborne pathogen detection using hyperspectral imaging

USDA-ARS?s Scientific Manuscript database

Foodborne pathogens can cause various diseases and even death when humans consume foods contaminated with microbial pathogens. Traditional culture-based direct plating methods are still the “gold standard” for presumptive-positive pathogen screening. Although considerable research has been devoted t...

Proposal of Xanthomonas translucens pv. pistaciae pv. nov., pathogenic to pistachio (Pistacia vera).

PubMed

Giblot-Ducray, Danièle; Marefat, Alireza; Gillings, Michael R; Parkinson, Neil M; Bowman, John P; Ophel-Keller, Kathy; Taylor, Cathy; Facelli, Evelina; Scott, Eileen S

2009-12-01

Strains of Xanthomonas translucens have caused dieback in the Australian pistachio industry for the last 15 years. Such pathogenicity to a dicotyledonous woody host contrasts with that of other pathovars of X. translucens, which are characterized by their pathogenicity to monocotyledonous plant families. Further investigations, using DNA-DNA hybridization, gyrB gene sequencing and integron screening, were conducted to confirm the taxonomic status of the X. translucens pathogenic to pistachio. DNA-DNA hybridization provided a clear classification, at the species level, of the pistachio pathogen as a X. translucens. In the gyrB-based phylogeny, strains of the pistachio pathogen clustered among the X. translucens pathovars as two distinct lineages. Integron screening revealed that the cassette arrays of strains of the pistachio pathogen were different from those of other Xanthomonas species, and again distinguished two groups. Together with previously reported pathogenicity data, these results confirm that the pistachio pathogen is a new pathovar of X. translucens and allow hypotheses about its origin. The proposed name is Xanthomonas translucens pv. pistaciae pv. nov.

Comparative Pathogenomics Reveals Horizontally Acquired Novel Virulence Genes in Fungi Infecting Cereal Hosts

PubMed Central

Gardiner, Donald M.; McDonald, Megan C.; Covarelli, Lorenzo; Solomon, Peter S.; Rusu, Anca G.; Marshall, Mhairi; Kazan, Kemal; Chakraborty, Sukumar; McDonald, Bruce A.; Manners, John M.

2012-01-01

Comparative analyses of pathogen genomes provide new insights into how pathogens have evolved common and divergent virulence strategies to invade related plant species. Fusarium crown and root rots are important diseases of wheat and barley world-wide. In Australia, these diseases are primarily caused by the fungal pathogen Fusarium pseudograminearum. Comparative genomic analyses showed that the F. pseudograminearum genome encodes proteins that are present in other fungal pathogens of cereals but absent in non-cereal pathogens. In some cases, these cereal pathogen specific genes were also found in bacteria associated with plants. Phylogenetic analysis of selected F. pseudograminearum genes supported the hypothesis of horizontal gene transfer into diverse cereal pathogens. Two horizontally acquired genes with no previously known role in fungal pathogenesis were studied functionally via gene knockout methods and shown to significantly affect virulence of F. pseudograminearum on the cereal hosts wheat and barley. Our results indicate using comparative genomics to identify genes specific to pathogens of related hosts reveals novel virulence genes and illustrates the importance of horizontal gene transfer in the evolution of plant infecting fungal pathogens. PMID:23028337

Machine learning for the meta-analyses of microbial pathogens' volatile signatures.

PubMed

Palma, Susana I C J; Traguedo, Ana P; Porteira, Ana R; Frias, Maria J; Gamboa, Hugo; Roque, Ana C A

2018-02-20

Non-invasive and fast diagnostic tools based on volatolomics hold great promise in the control of infectious diseases. However, the tools to identify microbial volatile organic compounds (VOCs) discriminating between human pathogens are still missing. Artificial intelligence is increasingly recognised as an essential tool in health sciences. Machine learning algorithms based in support vector machines and features selection tools were here applied to find sets of microbial VOCs with pathogen-discrimination power. Studies reporting VOCs emitted by human microbial pathogens published between 1977 and 2016 were used as source data. A set of 18 VOCs is sufficient to predict the identity of 11 microbial pathogens with high accuracy (77%), and precision (62-100%). There is one set of VOCs associated with each of the 11 pathogens which can predict the presence of that pathogen in a sample with high accuracy and precision (86-90%). The implemented pathogen classification methodology supports future database updates to include new pathogen-VOC data, which will enrich the classifiers. The sets of VOCs identified potentiate the improvement of the selectivity of non-invasive infection diagnostics using artificial olfaction devices.

Tandem mass spectrometry for the detection of plant pathogenic fungi and the effects of database composition on protein inferences.

PubMed

Padliya, Neerav D; Garrett, Wesley M; Campbell, Kimberly B; Tabb, David L; Cooper, Bret

2007-11-01

LC-MS/MS has demonstrated potential for detecting plant pathogens. Unlike PCR or ELISA, LC-MS/MS does not require pathogen-specific reagents for the detection of pathogen-specific proteins and peptides. However, the MS/MS approach we and others have explored does require a protein sequence reference database and database-search software to interpret tandem mass spectra. To evaluate the limitations of database composition on pathogen identification, we analyzed proteins from cultured Ustilago maydis, Phytophthora sojae, Fusarium graminearum, and Rhizoctonia solani by LC-MS/MS. When the search database did not contain sequences for a target pathogen, or contained sequences to related pathogens, target pathogen spectra were reliably matched to protein sequences from nontarget organisms, giving an illusion that proteins from nontarget organisms were identified. Our analysis demonstrates that when database-search software is used as part of the identification process, a paradox exists whereby additional sequences needed to detect a wide variety of possible organisms may lead to more cross-species protein matches and misidentification of pathogens.

PATHOGENS: VIEWS OF EPA'S PATHOGEN EQUIVALENCY COMMITTEE

EPA Science Inventory

This presentation reviews the pathogenic microorganisms that may be found in municipal sewage sludge and the commonly employed Class A and B processes for controlling pathogens. It notes how extensively they are used and discusses issues and concerns with their application. Pre...

Free-living pathogens: life-history constraints and strain competition.

PubMed

Caraco, Thomas; Wang, Ing-Nang

2008-02-07

Many pathogen life histories include a free-living stage, often with anatomical and physiological adaptations promoting persistence outside of host tissues. More durable particles presumably require that the pathogen metabolize more resources per particle. Therefore, we hypothesize functional dependencies, pleiotropic constraints, between the rate at which free-living particles decay outside of host tissues and other pathogen traits, including virulence, the probability of infecting a host upon contact, and pathogen reproduction within host tissues. Assuming that pathogen strains compete for hosts preemptively, we find patterns in trait dependencies predicting whether or not strain competition favors a highly persistent free-living stage.

Molecular assays reveal the presence and diversity of genes encoding pea footrot pathogenicity determinants in Nectria haematococca and in agricultural soils.

PubMed

Etebu, E; Osborn, A M

2009-05-01

The aim of this study was to develop molecular assays for investigating the presence and diversity of pathogenicity genes from the pea footrot pathogen Nectria haematococca (anamorph Fusarium solani f.sp. pisi) in soils. Polymerase chain reaction (PCR) assays were developed to amplify four N. haematococca pathogenicity genes (PDA, PEP1, PEP3 and PEP5) from isolates and soil-DNA from five agricultural fields with a prior footrot history. A collection of 15 fungi isolated on medium selective for Fusarium spp. exhibited variation in their virulence to peas as assessed via a disease index (DI: 0-5; no virulence to the highest virulence). PCR analyses showed that three isolates in which all four pathogenicity genes were detected resulted in the highest DI (>3.88). All four pathogenicity genes were detected in soil-DNA obtained from all five fields with a footrot disease history, but were not amplified from soils, which had no footrot history. Denaturing gradient gel electrophoresis and/or sequence analysis revealed diversity amongst the pathogenicity genes. The PCR assays developed herein enable the specific detection of pathogenic N. haematococca in soils without recourse to culture. Molecular assays that specifically target pathogenicity genes have the capacity to assess the presence of the footrot-causing pathogen in agricultural soils.

Immune Evasion Strategies of Pathogens in Macrophages: the Potential for Limiting Pathogen Transmission.

PubMed

Ren, Yuwei; Khan, Faheem Ahmed; Pandupuspitasari, Nuruliarizki Shinta; Zhang, Shujun

2017-01-01

Preventing pathogen transmission to a new host is of major interest to the immunologist and could benefit from a detailed investigation of pathogen immune evasion strategies. The first line of defense against pathogen invasion is provided by macrophages. When they sense pathogens, macrophages initiate signals to inflammatory and pro-inflammatory cytokines through pattern recognition receptors (PRRs) subsequently mediating phagocytosis and inflammation. The macrophage immune machinery classically includes two subsets: the activated M1 and the activated M2 that respond accordingly in diverse immune challenges. The lipid and glycogen metabolic pathways work together with the lysosome to help the mature phagosome to degrade and eliminate intracellular pathogens in macrophages. The viral evasion strategies are even more complex due to the interplay between autophagy and apoptosis. However, pathogens evolve several strategies to camouflage themselves against immune responses in order to ensure their survival, replication and transmission. These strategies include the muting of PRRs initiated inflammatory responses, attenuation of M1 and/or induction of M2 macrophages, suppression of autophago-lysosomal formation, interference with lipid and glycogen metabolism, and viral mediation of autophagy and apoptosis cross-talk to enhance viral replication. This review focuses on pathogen immune evasion methods and on the strategies used by the host against camouflaged pathogens.

Development of an aquatic pathogen database (AquaPathogen X) and its utilization in tracking emerging fish virus pathogens in North America

USGS Publications Warehouse

Emmenegger, E.J.; Kentop, E.; Thompson, T.M.; Pittam, S.; Ryan, A.; Keon, D.; Carlino, J.A.; Ranson, J.; Life, R.B.; Troyer, R.M.; Garver, K.A.; Kurath, G.

2011-01-01

The AquaPathogen X database is a template for recording information on individual isolates of aquatic pathogens and is freely available for download (http://wfrc.usgs.gov). This database can accommodate the nucleotide sequence data generated in molecular epidemiological studies along with the myriad of abiotic and biotic traits associated with isolates of various pathogens (e.g. viruses, parasites and bacteria) from multiple aquatic animal host species (e.g. fish, shellfish and shrimp). The cataloguing of isolates from different aquatic pathogens simultaneously is a unique feature to the AquaPathogen X database, which can be used in surveillance of emerging aquatic animal diseases and elucidation of key risk factors associated with pathogen incursions into new water systems. An application of the template database that stores the epidemiological profiles of fish virus isolates, called Fish ViroTrak, was also developed. Exported records for two aquatic rhabdovirus species emerging in North America were used in the implementation of two separate web-accessible databases: the Molecular Epidemiology of Aquatic Pathogens infectious haematopoietic necrosis virus (MEAP-IHNV) database (http://gis.nacse.org/ihnv/) released in 2006 and the MEAP- viral haemorrhagic septicaemia virus (http://gis.nacse.org/vhsv/) database released in 2010.

Systematic detection of positive selection in the human-pathogen interactome and lasting effects on infectious disease susceptibility.

PubMed

Corona, Erik; Wang, Liuyang; Ko, Dennis; Patel, Chirag J

2018-01-01

Infectious disease has shaped the natural genetic diversity of humans throughout the world. A new approach to capture positive selection driven by pathogens would provide information regarding pathogen exposure in distinct human populations and the constantly evolving arms race between host and disease-causing agents. We created a human pathogen interaction database and used the integrated haplotype score (iHS) to detect recent positive selection in genes that interact with proteins from 26 different pathogens. We used the Human Genome Diversity Panel to identify specific populations harboring pathogen-interacting genes that have undergone positive selection. We found that human genes that interact with 9 pathogen species show evidence of recent positive selection. These pathogens are Yersenia pestis, human immunodeficiency virus (HIV) 1, Zaire ebolavirus, Francisella tularensis, dengue virus, human respiratory syncytial virus, measles virus, Rubella virus, and Bacillus anthracis. For HIV-1, GWAS demonstrate that some naturally selected variants in the host-pathogen protein interaction networks continue to have functional consequences for susceptibility to these pathogens. We show that selected human genes were enriched for HIV susceptibility variants (identified through GWAS), providing further support for the hypothesis that ancient humans were exposed to lentivirus pandemics. Human genes in the Italian, Miao, and Biaka Pygmy populations that interact with Y. pestis show significant signs of selection. These results reveal some of the genetic footprints created by pathogens in the human genome that may have left lasting marks on susceptibility to infectious disease.

Transcriptome profiling of soybean (Glycine max) roots challenged with pathogenic and non-pathogenic isolates of Fusarium oxysporum.

PubMed

Lanubile, Alessandra; Muppirala, Usha K; Severin, Andrew J; Marocco, Adriano; Munkvold, Gary P

2015-12-21

Fusarium oxysporum is one of the most common fungal pathogens causing soybean root rot and seedling blight in U.S.A. In a recent study, significant variation in aggressiveness was observed among isolates of F. oxysporum collected from roots in Iowa, ranging from highly pathogenic to weakly or non-pathogenic isolates. We used RNA-seq analysis to investigate the molecular aspects of the interactions of a partially resistant soybean genotype with non-pathogenic/pathogenic isolates of F. oxysporum at 72 and 96 h post inoculation (hpi). Markedly different gene expression profiles were observed in response to the two isolates. A peak of highly differentially expressed genes (HDEGs) was triggered at 72 hpi in soybean roots and the number of HDEGs was about eight times higher in response to the pathogenic isolate compared to the non-pathogenic one (1,659 vs. 203 HDEGs, respectively). Furthermore, the magnitude of induction was much greater in response to the pathogenic isolate. This response included a stronger activation of defense-related genes, transcription factors, and genes involved in ethylene biosynthesis, secondary and sugar metabolism. The obtained data provide an important insight into the transcriptional responses of soybean-F. oxysporum interactions and illustrate the more drastic changes in the host transcriptome in response to the pathogenic isolate. These results may be useful in the developing new methods of broadening resistance of soybean to F. oxysporum, including the over-expression of key soybean genes.

Host-pathogen dynamics under sterilizing pathogens and fecundity-longevity trade-off in hosts.

PubMed

Janoušková, Eva; Berec, Luděk

2018-08-07

Infectious diseases are known to regulate population dynamics, an observation that underlies the use of pathogens as control agents of unwanted populations. Sterilizing rather than lethal pathogens are often suggested so as to avoid unnecessary suffering of the infected hosts. Until recently, models used to assess plausibility of pathogens as potential pest control agents have not included a possibility that reduced fecundity of the infected individuals may save their energy expenditure on reproduction and thus increase their longevity relative to the susceptible ones. Here, we develop a model of host-pathogen interaction that builds on this idea. We analyze the model for a variety of infection transmission functions, revealing that the indirect effect of sterilizing pathogens on mortality of the infected hosts, mediated by a fecundity-longevity trade-off, may cause hosts at endemic equilibria to attain densities higher than when there is no effect of pathogens on host mortality. On the other hand, an opposite outcome occurs when the fecundity-longevity trade-off is concave or when the degree of fecundity reduction by the pathogen is high enough. This points to a possibility that using sterilizing pathogens as agents of pest control may actually be less effective than previously thought, the more so since we also suggest that if sexual selection acts on the host species then the presence of sterilizing pathogens may even enhance host densities above the levels achieved without infection. Copyright © 2018 Elsevier Ltd. All rights reserved.

Molecular approaches for biosurveillance of the cucurbit downy mildew pathogen, Pseudoperonospora cubensis

USDA-ARS?s Scientific Manuscript database

Globalization has allowed for rapid movement of plant pathogens that threaten food security. Successful disease management largely depends in timely and accurate detection of plant pathogens causing epidemics. Thus, biosurveillance of epidemic plant pathogens such as Pseudoperonospora cubensis, the ...

Mucosal immunity to pathogenic intestinal bacteria.

PubMed

Perez-Lopez, Araceli; Behnsen, Judith; Nuccio, Sean-Paul; Raffatellu, Manuela

2016-03-01

The intestinal mucosa is a particularly dynamic environment in which the host constantly interacts with trillions of commensal microorganisms, known as the microbiota, and periodically interacts with pathogens of diverse nature. In this Review, we discuss how mucosal immunity is controlled in response to enteric bacterial pathogens, with a focus on the species that cause morbidity and mortality in humans. We explain how the microbiota can shape the immune response to pathogenic bacteria, and we detail innate and adaptive immune mechanisms that drive protective immunity against these pathogens. The vast diversity of the microbiota, pathogens and immune responses encountered in the intestines precludes discussion of all of the relevant players in this Review. Instead, we aim to provide a representative overview of how the intestinal immune system responds to pathogenic bacteria.

Impact of Vector Dispersal and Host-Plant Fidelity on the Dissemination of an Emerging Plant Pathogen

PubMed Central

Johannesen, Jes; Foissac, Xavier; Kehrli, Patrik; Maixner, Michael

2012-01-01

Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a) and its vector (Hyalesthes obsoletus: Cixiidae) affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector. PMID:23284774

Comparative genomics of transport proteins in probiotic and pathogenic Escherichia coli and Salmonella enterica strains.

PubMed

Do, Jimmy; Zafar, Hassan; Saier, Milton H

2017-06-01

Escherichia coli is a genetically diverse species that can be pathogenic, probiotic, commensal, or a harmless laboratory strain. Pathogenic strains of E. coli cause urinary tract infections, diarrhea, hemorrhagic colitis, and pyelonephritis, while the two known probiotic E. coli strains combat inflammatory bowel disease and play a role in immunomodulation. Salmonella enterica, a close relative of E. coli, includes two important pathogenic serovars, Typhi and Typhimurium, causing typhoid fever and enterocolitis in humans, respectively, with the latter strain also causing a lethal typhoid fever-like disease in mice. In this study, we identify the transport systems and their substrates within seven E. coli strains: two probiotic strains, two extracellular pathogens, two intracellular pathogens, and K-12, as well as the two intracellular pathogenic S. enterica strains noted above. Transport systems characteristic of each probiotic or pathogenic species were thus identified, and the tabulated results obtained with all of these strains were compared. We found that the probiotic and pathogenic strains generally contain more iron-siderophore and sugar transporters than E. coli K-12. Pathogens have increased numbers of pore-forming toxins, protein secretion systems, decarboxylation-driven Na + exporters, electron flow-driven monovalent cation exporters, and putative transporters of unknown function compared to the probiotic strains. Both pathogens and probiotic strains encode metabolite transporters that reflect their intracellular versus extracellular environments. The results indicate that the probiotic strains live extracellularly. It seems that relatively few virulence factors can convert a beneficial or commensal microorganism into a pathogen. Taken together, the results reveal the distinguishing features of these strains and provide a starting point for future engineering of beneficial enteric bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tick salivary compounds: their role in modulation of host defences and pathogen transmission

PubMed Central

Kazimírová, Mária; Štibrániová, Iveta

2013-01-01

Ticks require blood meal to complete development and reproduction. Multifunctional tick salivary glands play a pivotal role in tick feeding and transmission of pathogens. Tick salivary molecules injected into the host modulate host defence responses to the benefit of the feeding ticks. To colonize tick organs, tick-borne microorganisms must overcome several barriers, i.e., tick gut membrane, tick immunity, and moulting. Tick-borne pathogens co-evolved with their vectors and hosts and developed molecular adaptations to avoid adverse effects of tick and host defences. Large gaps exist in the knowledge of survival strategies of tick-borne microorganisms and on the molecular mechanisms of tick-host-pathogen interactions. Prior to transmission to a host, the microorganisms penetrate and multiply in tick salivary glands. As soon as the tick is attached to a host, gene expression and production of salivary molecules is upregulated, primarily to facilitate feeding and avoid tick rejection by the host. Pathogens exploit tick salivary molecules for their survival and multiplication in the vector and transmission to and establishment in the hosts. Promotion of pathogen transmission by bioactive molecules in tick saliva was described as saliva-assisted transmission (SAT). SAT candidates comprise compounds with anti-haemostatic, anti-inflammatory and immunomodulatory functions, but the molecular mechanisms by which they mediate pathogen transmission are largely unknown. To date only a few tick salivary molecules associated with specific pathogen transmission have been identified and their functions partially elucidated. Advanced molecular techniques are applied in studying tick-host-pathogen interactions and provide information on expression of vector and pathogen genes during pathogen acquisition, establishment and transmission. Understanding the molecular events on the tick-host-pathogen interface may lead to development of new strategies to control tick-borne diseases. PMID:23971008

The ability of algal organic matter and surface runoff to promote the abundance of pathogenic and non-pathogenic strains of Vibrio parahaemolyticus in Long Island Sound, USA

PubMed Central

Thickman, Jake D.

2017-01-01

Food safety is a major concern in the shellfish industry, as severe illness can result from consuming shellfish that have accumulated waterborne pathogens. Shellfish harvesting areas are typically monitored for indicator bacteria such as fecal coliforms that serve as proxies for enteric pathogens although these indicators have shown little relation to some naturally occurring pathogenic bacteria such as Vibrio parahaemolyticus. To examine the dynamics and ecology of pathogenic and non-pathogenic strains of V. parahaemolyticus and address the relevance of indicator bacteria in predicting V. parahaemolyticus concentrations, field surveys and experiments were carried out in western Long Island Sound, NY, USA, a region that has experienced recent outbreaks of shellfish contaminated with V. parahaemolyticus. Pathogenic and non-pathogenic strains were quantified via PCR detection of marker genes and most probable number techniques. Field survey data showed little correspondence between fecal coliforms and V. parahaemolyticus, but significant correlations between V. parahaemolyticus and an alternative indicator, enterococci, and between V. parahaemolyticus and short-term (48 h) rainfall were observed. Experiments demonstrated that enrichment of seawater with phytoplankton-derived dissolved organic matter significantly increased the concentration of total V. parahaemolyticus and the presence pathogenic V. parahaemolyticus, but higher temperatures did not. Collectively, these study results suggest that fecal coliforms may fail to account for the full suite of important shellfish pathogens but that enterococci could provide a potential alternative or supplement to shellfish sanitation monitoring. Given the ability of algal-derived dissolved organic matter to promote the growth of pathogenic V. parahaemolyticus, restricting nutrient inputs into coastal water bodies that promote algal blooms may indirectly decrease the proliferation of V. parahaemolyticus and protect public health. PMID:29020074

Impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.

PubMed

Johannesen, Jes; Foissac, Xavier; Kehrli, Patrik; Maixner, Michael

2012-01-01

Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a) and its vector (Hyalesthes obsoletus: Cixiidae) affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector.

The ability of algal organic matter and surface runoff to promote the abundance of pathogenic and non-pathogenic strains of Vibrio parahaemolyticus in Long Island Sound, USA.

PubMed

Thickman, Jake D; Gobler, Christopher J

2017-01-01

Food safety is a major concern in the shellfish industry, as severe illness can result from consuming shellfish that have accumulated waterborne pathogens. Shellfish harvesting areas are typically monitored for indicator bacteria such as fecal coliforms that serve as proxies for enteric pathogens although these indicators have shown little relation to some naturally occurring pathogenic bacteria such as Vibrio parahaemolyticus. To examine the dynamics and ecology of pathogenic and non-pathogenic strains of V. parahaemolyticus and address the relevance of indicator bacteria in predicting V. parahaemolyticus concentrations, field surveys and experiments were carried out in western Long Island Sound, NY, USA, a region that has experienced recent outbreaks of shellfish contaminated with V. parahaemolyticus. Pathogenic and non-pathogenic strains were quantified via PCR detection of marker genes and most probable number techniques. Field survey data showed little correspondence between fecal coliforms and V. parahaemolyticus, but significant correlations between V. parahaemolyticus and an alternative indicator, enterococci, and between V. parahaemolyticus and short-term (48 h) rainfall were observed. Experiments demonstrated that enrichment of seawater with phytoplankton-derived dissolved organic matter significantly increased the concentration of total V. parahaemolyticus and the presence pathogenic V. parahaemolyticus, but higher temperatures did not. Collectively, these study results suggest that fecal coliforms may fail to account for the full suite of important shellfish pathogens but that enterococci could provide a potential alternative or supplement to shellfish sanitation monitoring. Given the ability of algal-derived dissolved organic matter to promote the growth of pathogenic V. parahaemolyticus, restricting nutrient inputs into coastal water bodies that promote algal blooms may indirectly decrease the proliferation of V. parahaemolyticus and protect public health.

Pathogenic agents in freshwater resources

NASA Astrophysics Data System (ADS)

Geldreich, Edwin E.

1996-02-01

Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen.As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology.Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

Multiplex detection of agricultural pathogens

DOEpatents

Siezak, Thomas R.; Gardner, Shea; Torres, Clinton; Vitalis, Elizabeth; Lenhoff, Raymond J.

2013-01-15

Described are kits and methods useful for detection of agricultural pathogens in a sample. Genomic sequence information from agricultural pathogens was analyzed to identify signature sequences, e.g., polynucleotide sequences useful for confirming the presence or absence of a pathogen in a sample. Primer and probe sets were designed and optimized for use in a PCR based, multiplexed Luminex assay and/or an array assay to successfully identify the presence or absence of pathogens in a sample.

Distribution of triclosan-resistant genes in major pathogenic microorganisms revealed by metagenome and genome-wide analysis

PubMed Central

Khan, Raees; Roy, Nazish; Choi, Kihyuck

2018-01-01

The substantial use of triclosan (TCS) has been aimed to kill pathogenic bacteria, but TCS resistance seems to be prevalent in microbial species and limited knowledge exists about TCS resistance determinants in a majority of pathogenic bacteria. We aimed to evaluate the distribution of TCS resistance determinants in major pathogenic bacteria (N = 231) and to assess the enrichment of potentially pathogenic genera in TCS contaminated environments. A TCS-resistant gene (TRG) database was constructed and experimentally validated to predict TCS resistance in major pathogenic bacteria. Genome-wide in silico analysis was performed to define the distribution of TCS-resistant determinants in major pathogens. Microbiome analysis of TCS contaminated soil samples was also performed to investigate the abundance of TCS-resistant pathogens. We experimentally confirmed that TCS resistance could be accurately predicted using genome-wide in silico analysis against TRG database. Predicted TCS resistant phenotypes were observed in all of the tested bacterial strains (N = 17), and heterologous expression of selected TCS resistant genes from those strains conferred expected levels of TCS resistance in an alternative host Escherichia coli. Moreover, genome-wide analysis revealed that potential TCS resistance determinants were abundant among the majority of human-associated pathogens (79%) and soil-borne plant pathogenic bacteria (98%). These included a variety of enoyl-acyl carrier protein reductase (ENRs) homologues, AcrB efflux pumps, and ENR substitutions. FabI ENR, which is the only known effective target for TCS, was either co-localized with other TCS resistance determinants or had TCS resistance-associated substitutions. Furthermore, microbiome analysis revealed that pathogenic genera with intrinsic TCS-resistant determinants exist in TCS contaminated environments. We conclude that TCS may not be as effective against the majority of bacterial pathogens as previously presumed. Further, the excessive use of this biocide in natural environments may selectively enrich for not only TCS-resistant bacterial pathogens, but possibly for additional resistance to multiple antibiotics. PMID:29420585

Spatial variation in disease resistance: from molecules to metapopulations

PubMed Central

Laine, Anna-Liisa; Burdon, Jeremy J.; Dodds, Peter N.; Thrall, Peter H.

2010-01-01

Summary Variation in disease resistance is a widespread phenomenon in wild plant-pathogen associations. Here, we review current literature on natural plant-pathogen associations to determine how diversity in disease resistance is distributed at different hierarchical levels – within host individuals, within host populations, among host populations at the metapopulation scale and at larger regional scales. We find diversity in resistance across all spatial scales examined. Furthermore, variability seems to be the best counter-defence of plants against their rapidly evolving pathogens. We find that higher diversity of resistance phenotypes also results in higher levels of resistance at the population level. Overall, we find that wild plant populations are more likely to be susceptible than resistant to their pathogens. However, the degree of resistance differs strikingly depending on the origin of the pathogen strains used in experimental inoculation studies. Plant populations are on average 16% more resistant to allopatric pathogen strains than they are to strains that occur within the same population (48 % vs. 32 % respectively). Pathogen dispersal mode affects levels of resistance in natural plant populations with lowest levels detected for hosts of airborne pathogens and highest for waterborne pathogens. Detailed analysis of two model systems, Linum marginale infected by Melampsora lini, and Plantago lanceolata infected by Podosphaera plantaginis, show that the amount of variation in disease resistance declines towards higher spatial scales as we move from individual hosts to metapopulations, but evaluation of multiple spatial scales is needed to fully capture the structure of disease resistance. Synthesis: Variation in disease resistance is ubiquitous in wild plant-pathogen associations. While the debate over whether the resistance structure of plant populations is determined by pathogen-imposed selection versus non-adaptive processes remains unresolved, we do report examples of pathogen-imposed selection on host resistance. Here we highlight the importance of measuring resistance across multiple spatial scales, and of using sympatric strains when looking for signs of coevolution in wild plant-pathogen interactions. PMID:21243068

Communicable Diseases Prioritized According to Their Public Health Relevance, Sweden, 2013

PubMed Central

Dahl, Viktor; Tegnell, Anders; Wallensten, Anders

2015-01-01

To establish strategic priorities for the Public Health Agency of Sweden we prioritized pathogens according to their public health relevance in Sweden in order to guide resource allocation. We then compared the outcome to ongoing surveillance. We used a modified prioritization method developed at the Robert Koch Institute in Germany. In a Delphi process experts scored pathogens according to ten variables. We ranked the pathogens according to the total score and divided them into four priority groups. We then compared the priority groups to self-reported time spent on surveillance by epidemiologists and ongoing programmes for surveillance through mandatory and/or voluntary notifications and for surveillance of typing results. 106 pathogens were scored. The result of the prioritization process was similar to the outcome of the prioritization in Germany. Common pathogens such as calicivirus and Influenza virus as well as blood-borne pathogens such as human immunodeficiency virus, hepatitis B and C virus, gastro-intestinal infections such as Campylobacter and Salmonella and vector-borne pathogens such as Borrelia were all in the highest priority group. 63% of time spent by epidemiologists on surveillance was spent on pathogens in the highest priority group and all pathogens in the highest priority group, except for Borrelia and varicella-zoster virus, were under surveillance through notifications. Ten pathogens in the highest priority group (Borrelia, calicivirus, Campylobacter, Echinococcus multilocularis, hepatitis C virus, HIV, respiratory syncytial virus, SARS- and MERS coronavirus, tick-borne encephalitis virus and varicella-zoster virus) did not have any surveillance of typing results. We will evaluate the possibilities of surveillance for the pathogens in the highest priority group where we currently do not have any ongoing surveillance and evaluate the need of surveillance for the pathogens from the low priority group where there is ongoing surveillance in order to focus our work on the pathogens with the highest relevance. PMID:26397699

Transport and fate of microbial pathogens in agricultural settings

USDA-ARS?s Scientific Manuscript database

An understanding of the transport and survival of microbial pathogens (pathogens hereafter) in agricultural settings is needed to assess the risk of pathogen contamination to water and food resources, and to develop control strategies and treatment options. However, many knowledge gaps still remain ...

Novel methods for pathogen control in livestock preharvest: An update

USDA-ARS?s Scientific Manuscript database

Pathogenic bacteria are found asymptomatically within and on food animals, which often results in pathogen entry into the food chain, causing human illnesses. Slaughter and processing plants do an outstanding job in reducing pathogen contamination through the use of intervention strategies after sl...

Microbiology: Detection of Bacterial Pathogens and Their Occurrence.

ERIC Educational Resources Information Center

Reasoner, Donald J.

1978-01-01

Presents a literature review of bacterial pathogens that are related to water pollution, covering publications from 1976-77. This review includes: (1) bacterial pathogens in animals; and (2) detection and identification of waterborne bacterial pathogens. A list of 129 references is also presented. (HM)

The enemy within: phloem-limited pathogens

USDA-ARS?s Scientific Manuscript database

The growing impact of phloem-limited pathogens on high-value crops has led to a renewed interest in understanding how they cause disease. Although these pathogens cause substantial crop losses, many are poorly characterized. In this review, we present examples of phloem-limited pathogens that includ...

Pathogen reduction in human plasma using an ultrashort pulsed laser

USDA-ARS?s Scientific Manuscript database

Pathogen reduction is an ideal approach to ensure the continued safety of the blood supply against emerging pathogens. However, the currently licensed pathogen reduction techniques are ineffective against non-enveloped viruses, and they introduce chemicals with concerns of side effects which prevent...

Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting.

PubMed

Zilbermintz, Leeor; Leonardi, William; Jeong, Sun-Young; Sjodt, Megan; McComb, Ryan; Ho, Chi-Lee C; Retterer, Cary; Gharaibeh, Dima; Zamani, Rouzbeh; Soloveva, Veronica; Bavari, Sina; Levitin, Anastasia; West, Joel; Bradley, Kenneth A; Clubb, Robert T; Cohen, Stanley N; Gupta, Vivek; Martchenko, Mikhail

2015-08-27

A longstanding and still-increasing threat to the effective treatment of infectious diseases is resistance to antimicrobial countermeasures. Potentially, the targeting of host proteins and pathways essential for the detrimental effects of pathogens offers an approach that may discover broad-spectrum anti-pathogen countermeasures and circumvent the effects of pathogen mutations leading to resistance. Here we report implementation of a strategy for discovering broad-spectrum host-oriented therapies against multiple pathogenic agents by multiplex screening of drugs for protection against the detrimental effects of multiple pathogens, identification of host cell pathways inhibited by the drug, and screening for effects of the agent on other pathogens exploiting the same pathway. We show that a clinically used antimalarial drug, Amodiaquine, discovered by this strategy, protects host cells against infection by multiple toxins and viruses by inhibiting host cathepsin B. Our results reveal the practicality of discovering broadly acting anti-pathogen countermeasures that target host proteins exploited by pathogens.

Loss of competition in the outside host environment generates outbreaks of environmental opportunist pathogens.

PubMed

Anttila, Jani; Ruokolainen, Lasse; Kaitala, Veijo; Laakso, Jouni

2013-01-01

Environmentally transmitted pathogens face ecological interactions (e.g., competition, predation, parasitism) in the outside-host environment and host immune system during infection. Despite the ubiquitousness of environmental opportunist pathogens, traditional epidemiology focuses on obligatory pathogens incapable of environmental growth. Here we ask how competitive interactions in the outside-host environment affect the dynamics of an opportunist pathogen. We present a model coupling the classical SI and Lotka-Volterra competition models. In this model we compare a linear infectivity response and a sigmoidal infectivity response. An important assumption is that pathogen virulence is traded off with competitive ability in the environment. Removing this trade-off easily results in host extinction. The sigmoidal response is associated with catastrophic appearances of disease outbreaks when outside-host species richness, or overall competition pressure, decreases. This indicates that alleviating outside-host competition with antibacterial substances that also target the competitors can have unexpected outcomes by providing benefits for opportunist pathogens. These findings may help in developing alternative ways of controlling environmental opportunist pathogens.

Water relations in the interaction of foliar bacterial pathogens with plants.

PubMed

Beattie, Gwyn A

2011-01-01

This review examines the many ways in which water influences the relations between foliar bacterial pathogens and plants. As a limited resource in aerial plant tissues, water is subject to manipulation by both plants and pathogens. A model is emerging that suggests that plants actively promote localized desiccation at the infection site and thus restrict pathogen growth as one component of defense. Similarly, many foliar pathogens manipulate water relations as one component of pathogenesis. Nonvascular pathogens do this using effectors and other molecules to alter hormonal responses and enhance intercellular watersoaking, whereas vascular pathogens use many mechanisms to cause wilt. Because of water limitations on phyllosphere surfaces, bacterial colonists, including pathogens, benefit from the protective effects of cellular aggregation, synthesis of hygroscopic polymers, and uptake and production of osmoprotective compounds. Moreover, these bacteria employ tactics for scavenging and distributing water to overcome water-driven barriers to nutrient acquisition, movement, and signal exchange on plant surfaces. Copyright © 2011 by Annual Reviews. All rights reserved.

Host plant-dependent phenotypic reversion of Ralstonia solanacearum from non-pathogenic to pathogenic forms via alterations in the phcA gene.

PubMed

Poussier, Stéphane; Thoquet, Philippe; Trigalet-Demery, Danièle; Barthet, Séverine; Meyer, Damien; Arlat, Matthieu; Trigalet, André

2003-08-01

Ralstonia solanacearum is a plant pathogenic bacterium that undergoes a spontaneous phenotypic conversion (PC) from a wild-type pathogenic to a non-pathogenic form. PC is often associated with mutations in phcA, which is a key virulence regulatory gene. Until now, reversion to the wild-type pathogenic form has not been observed for PC variants and the biological significance of PC has been questioned. In this study, we characterized various alterations in phcA (eight IS element insertions, three tandem duplications, seven deletions and a base substitution) in 19 PC mutants from the model strain GMI1000. In five of these variants, reversion to the pathogenic form was observed in planta, while no reversion was ever noticed in vitro whatever culture media used. However, reversion was observed for a 64 bp tandem duplication in vitro in the presence of tomato root exudate. This is the first report showing a complete cycle of phenotypic conversion/reversion in a plant pathogenic bacterium.

Statistical Physics of T-Cell Development and Pathogen Specificity

NASA Astrophysics Data System (ADS)

Košmrlj, Andrej; Kardar, Mehran; Chakraborty, Arup K.

2013-04-01

In addition to an innate immune system that battles pathogens in a nonspecific fashion, higher organisms, such as humans, possess an adaptive immune system to combat diverse (and evolving) microbial pathogens. Remarkably, the adaptive immune system mounts pathogen-specific responses, which can be recalled upon reinfection with the same pathogen. It is difficult to see how the adaptive immune system can be preprogrammed to respond specifically to a vast and unknown set of pathogens. Although major advances have been made in understanding pertinent molecular and cellular phenomena, the precise principles that govern many aspects of an immune response are largely unknown. We discuss complementary approaches from statistical mechanics and cell biology that can shed light on how key components of the adaptive immune system, T cells, develop to enable pathogen-specific responses against many diverse pathogens. The mechanistic understanding that emerges has implications for how host genetics may influence the development of T cells with differing responses to the human immunodeficiency virus (HIV) infection.

The trans-kingdom identification of negative regulators of pathogen hypervirulence

PubMed Central

Brown, Neil A.; Urban, Martin; Hammond-Kosack, Kim E.

2015-01-01

Modern society and global ecosystems are increasingly under threat from pathogens, which cause a plethora of human, animal, invertebrate and plant diseases. Of increasing concern is the trans-kingdom tendency for increased pathogen virulence that is beginning to emerge in natural, clinical and agricultural settings. The study of pathogenicity has revealed multiple examples of convergently evolved virulence mechanisms. Originally described as rare, but increasingly common, are interactions where a single gene deletion in a pathogenic species causes hypervirulence. This review utilised the pathogen–host interaction database (www.PHI-base.org) to identify 112 hypervirulent mutations from 37 pathogen species, and subsequently interrogates the trans-kingdom, conserved, molecular, biochemical and cellular themes that cause hypervirulence. This study investigates 22 animal and 15 plant pathogens including 17 bacterial and 17 fungal species. Finally, the evolutionary significance and trans-kingdom requirement for negative regulators of hypervirulence and the implication of pathogen hypervirulence and emerging infectious diseases on society are discussed. PMID:26468211

Arginase activity in pathogenic and non-pathogenic species of Leishmania parasites.

PubMed

Badirzadeh, Alireza; Taheri, Tahereh; Taslimi, Yasaman; Abdossamadi, Zahra; Heidari-Kharaji, Maryam; Gholami, Elham; Sedaghat, Baharehsadat; Niyyati, Maryam; Rafati, Sima

2017-07-01

Proliferation of Leishmania (L.) parasites depends on polyamine availability, which can be generated by the L-arginine catabolism and the enzymatic activity of arginase (ARG) of the parasites and of the mammalian hosts. In the present study, we characterized and compared the arginase (arg) genes from pathogenic L. major and L. tropica and from non-pathogenic L. tarentolae. We quantified the level of the ARG activity in promastigotes and macrophages infected with pathogenic L. major and L. tropica and non-pathogenic L. tarentolae amastigotes. The ARG's amino acid sequences of the pathogenic and non-pathogenic Leishmania demonstrated virtually 98.6% and 88% identities with the reference L. major Friedlin ARG. Higher ARG activity was observed in all pathogenic promastigotes as compared to non-pathogenic L. tarentolae. In vitro infection of human macrophage cell line (THP1) with pathogenic and non-pathogenic Leishmania spp. resulted in increased ARG activities in the infected macrophages. The ARG activities present in vivo were assessed in susceptible BALB/c and resistant C57BL/6 mice infected with L. major, L. tropica and L. tarentolae. We demonstrated that during the development of the infection, ARG is induced in both strains of mice infected with pathogenic Leishmania. However, in L. major infected BALB/c mice, the induction of ARG and parasite load increased simultaneously according to the time course of infection, whereas in C57BL/6 mice, the enzyme is upregulated solely during the period of footpad swelling. In L. tropica infected mice, the footpads' swellings were slow to develop and demonstrated minimal cutaneous pathology and ARG activity. In contrast, ARG activity was undetectable in mice inoculated with the non-pathogenic L. tarentolae. Our data suggest that infection by Leishmania parasites can increase ARG activity of the host and provides essential polyamines for parasite salvage and its replication. Moreover, the ARG of Leishmania is vital for parasite proliferation and required for infection in mice. ARG activity can be used as one of the main marker of the disease severity.

Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels.

PubMed

Pieretti, Isabelle; Royer, Monique; Barbe, Valérie; Carrere, Sébastien; Koebnik, Ralf; Couloux, Arnaud; Darrasse, Armelle; Gouzy, Jérôme; Jacques, Marie-Agnès; Lauber, Emmanuelle; Manceau, Charles; Mangenot, Sophie; Poussier, Stéphane; Segurens, Béatrice; Szurek, Boris; Verdier, Valérie; Arlat, Matthieu; Gabriel, Dean W; Rott, Philippe; Cociancich, Stéphane

2012-11-21

Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa-another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity. Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the "artillery" of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity). Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism specific to X. albilineans were identified, supposing that X. albilineans has a reduced artillery compared to other pathogenic Xanthomonas species. Particular attention has therefore been given to genomic features specific to X. albilineans making it more capable of evading sugarcane surveillance systems or resisting sugarcane defense systems. This study confirms that X. albilineans is a highly distinctive species within the genus Xanthomonas, and opens new perpectives towards a greater understanding of the pathogenicity of this destructive sugarcane pathogen.

Arginase activity in pathogenic and non-pathogenic species of Leishmania parasites

PubMed Central

Badirzadeh, Alireza; Taheri, Tahereh; Taslimi, Yasaman; Abdossamadi, Zahra; Heidari-Kharaji, Maryam; Gholami, Elham; Sedaghat, Baharehsadat; Niyyati, Maryam

2017-01-01

Proliferation of Leishmania (L.) parasites depends on polyamine availability, which can be generated by the L-arginine catabolism and the enzymatic activity of arginase (ARG) of the parasites and of the mammalian hosts. In the present study, we characterized and compared the arginase (arg) genes from pathogenic L. major and L. tropica and from non-pathogenic L. tarentolae. We quantified the level of the ARG activity in promastigotes and macrophages infected with pathogenic L. major and L. tropica and non-pathogenic L. tarentolae amastigotes. The ARG's amino acid sequences of the pathogenic and non-pathogenic Leishmania demonstrated virtually 98.6% and 88% identities with the reference L. major Friedlin ARG. Higher ARG activity was observed in all pathogenic promastigotes as compared to non-pathogenic L. tarentolae. In vitro infection of human macrophage cell line (THP1) with pathogenic and non-pathogenic Leishmania spp. resulted in increased ARG activities in the infected macrophages. The ARG activities present in vivo were assessed in susceptible BALB/c and resistant C57BL/6 mice infected with L. major, L. tropica and L. tarentolae. We demonstrated that during the development of the infection, ARG is induced in both strains of mice infected with pathogenic Leishmania. However, in L. major infected BALB/c mice, the induction of ARG and parasite load increased simultaneously according to the time course of infection, whereas in C57BL/6 mice, the enzyme is upregulated solely during the period of footpad swelling. In L. tropica infected mice, the footpads' swellings were slow to develop and demonstrated minimal cutaneous pathology and ARG activity. In contrast, ARG activity was undetectable in mice inoculated with the non-pathogenic L. tarentolae. Our data suggest that infection by Leishmania parasites can increase ARG activity of the host and provides essential polyamines for parasite salvage and its replication. Moreover, the ARG of Leishmania is vital for parasite proliferation and required for infection in mice. ARG activity can be used as one of the main marker of the disease severity. PMID:28708893

Free-living pathogens: life-history constraints and strain competition

PubMed Central

Caraco, Thomas; Wang, Ing-Nang

2008-01-01

Many pathogen life histories include a free-living stage, often with anatomical and physiological adaptations promoting persistence outside of host tissues. More durable particles presumably require that the pathogen metabolize more resources per particle. Therefore, we hypothesize functional dependencies, pleiotropic constraints, between the rate at which free-living particles decay outside of host tissues and other pathogen traits, including virulence, the probability of infecting a host upon contact, and pathogen reproduction within host tissues. Assuming that pathogen strains compete for hosts preemptively, we find patterns in trait dependencies predicting whether or not strain competition favors a highly persistent free-living stage. PMID:18062992

Pathogen Transmission from Humans to Great Apes is a Growing Threat to Primate Conservation.

PubMed

Dunay, Emily; Apakupakul, Kathleen; Leard, Stephen; Palmer, Jamie L; Deem, Sharon L

2018-01-23

All six great ape species are listed as endangered or critically endangered by the IUCN and experiencing decreasing population trends. One of the threats to these non-human primates is the transmission of pathogens from humans. We conducted a literature review on occurrences of pathogen transmission from humans to great apes to highlight this often underappreciated issue. In total, we found 33 individual occurrences of probable or confirmed pathogen transmission from humans to great apes: 23 involved both pathogen and disease transmission, 7 pathogen transmission only, 2 positive antibody titers to zoonotic pathogens, and 1 pathogen transmission with probable disease. Great ape populations were categorized into captive, semi-free-living, and free-living conditions. The majority of occurrences involved chimpanzees (Pan troglodytes) (n = 23) or mountain gorillas (Gorilla beringei beringei) (n = 8). These findings have implications for conservation efforts and management of endangered great ape populations. Future efforts should focus on monitoring and addressing zoonotic pathogen and disease transmission between humans, great ape species, and other taxa to ensure the health of humans, wild and domestic animals, and the ecosystems we share.

Pathogen variation and urea influence selection and success of Streptomyces mixtures in biological control.

PubMed

Otto-Hanson, L K; Grabau, Z; Rosen, C; Salomon, C E; Kinkel, L L

2013-01-01

Success in biological control of plant diseases remains inconsistent in the field. A collection of well-characterized Streptomyces antagonists (n = 19 isolates) was tested for their capacities to inhibit pathogenic Streptomyces scabies (n = 15 isolates). There was significant variation among antagonists in ability to inhibit pathogen isolates and among pathogens in their susceptibility to inhibition. Only one antagonist could inhibit all pathogens, and antagonist-pathogen interactions were highly specific, highlighting the limitations of single-strain inoculum in biological control. However, the collection of pathogens could be inhibited by several combinations of antagonists, suggesting the potential for successful antagonist mixtures. Urea generally increased effectiveness of antagonists at inhibiting pathogens in vitro (increased mean inhibition zones) but its specific effects varied among antagonist-pathogen combinations. In greenhouse trials, urea enhanced the effectiveness of antagonist mixtures relative to individual antagonists in controlling potato scab. Although antagonist mixtures were frequently antagonistic in the absence of urea, all n= 2 and n = 3 antagonist-isolate combinations were synergistic in the presence of urea. This work provides insights into the efficacy of single- versus multiple-strain inocula in biological control and on the potential for nutrients to influence mixture success.

Survival of the Fittest: How Bacterial Pathogens Utilize Bile To Enhance Infection

PubMed Central

Sistrunk, Jeticia R.; Nickerson, Kourtney P.; Chanin, Rachael B.; Rasko, David A.

2016-01-01

SUMMARY Bacterial pathogens have coevolved with humans in order to efficiently infect, replicate within, and be transmitted to new hosts to ensure survival and a continual infection cycle. For enteric pathogens, the ability to adapt to numerous host factors under the harsh conditions of the gastrointestinal tract is critical for establishing infection. One such host factor readily encountered by enteric bacteria is bile, an innately antimicrobial detergent-like compound essential for digestion and nutrient absorption. Not only have enteric pathogens evolved to resist the bactericidal conditions of bile, but these bacteria also utilize bile as a signal to enhance virulence regulation for efficient infection. This review provides a comprehensive and up-to-date analysis of bile-related research with enteric pathogens. From common responses to the unique expression of specific virulence factors, each pathogen has overcome significant challenges to establish infection in the gastrointestinal tract. Utilization of bile as a signal to modulate virulence factor expression has led to important insights for our understanding of virulence mechanisms for many pathogens. Further research on enteric pathogens exposed to this in vivo signal will benefit therapeutic and vaccine development and ultimately enhance our success at combating such elite pathogens. PMID:27464994

Evolution of Compatibility Range in the Rice-Magnaporthe oryzae System: An Uneven Distribution of R Genes Between Rice Subspecies.

PubMed

Gallet, Romain; Fontaine, Colin; Bonnot, François; Milazzo, Joëlle; Tertois, Christophe; Adreit, Henri; Ravigné, Virginie; Fournier, Elisabeth; Tharreau, Didier

2016-04-01

Efficient strategies for limiting the impact of pathogens on crops require a good understanding of the factors underlying the evolution of compatibility range for the pathogens and host plants, i.e., the set of host genotypes that a particular pathogen genotype can infect and the set of pathogen genotypes that can infect a particular host genotype. Until now, little is known about the evolutionary and ecological factors driving compatibility ranges in systems implicating crop plants. We studied the evolution of host and pathogen compatibility ranges for rice blast disease, which is caused by the ascomycete Magnaporthe oryzae. We challenged 61 rice varieties from three rice subspecies with 31 strains of M. oryzae collected worldwide from all major known genetic groups. We determined the compatibility range of each plant variety and pathogen genotype and the severity of each plant-pathogen interaction. Compatibility ranges differed between rice subspecies, with the most resistant subspecies selecting for pathogens with broader compatibility ranges and the least resistant subspecies selecting for pathogens with narrower compatibility ranges. These results are consistent with a nested distribution of R genes between rice subspecies.

The effect of tar spot pathogen on host plant carbon balance and its possible consequences on a tundra ecosystem.

PubMed

Masumoto, Shota; Uchida, Masaki; Tojo, Motoaki; Herrero, Maria Luz; Mori, Akira S; Imura, Satoshi

2018-03-01

In Arctic tundra, plant pathogens have substantial effects on the growth and survival of hosts, and impacts on the carbon balance at the scale of ecological systems. To understand these effects on carbon dynamics across different scales including plant organ, individual, population and ecosystem, we focused on two primary factors: host productivity reduction and carbon consumption by the pathogen. We measured the effect of the pathogen on photosynthetic and respiratory activity in the host. We also measured respiration and the amount of carbon in the pathogen. We constructed a model based on these two factors, and calculated pathogenic effects on the carbon balance at different organismal and ecological scales. We found that carbon was reduced in infected leaves by 118% compared with healthy leaves; the major factor causing this loss was pathogenic carbon consumption. The carbon balance at the population and ecosystem levels decreased by 35% and 20%, respectively, at an infection rate of 30%. This case study provides the first evidence that a host plant can lose more carbon through pathogenic carbon consumption than through a reduction in productivity. Such a pathogenic effect could greatly change ecosystem carbon cycling without decreasing annual productivity.

The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens.

PubMed

Sánchez-Vallet, Andrea; Fouché, Simone; Fudal, Isabelle; Hartmann, Fanny E; Soyer, Jessica L; Tellier, Aurélien; Croll, Daniel

2018-05-16

Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation. Expected final online publication date for the Annual Review of Phytopathology Volume 56 is August 25, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Infection processes of xylem-colonizing pathogenic bacteria: possible explanations for the scarcity of qualitative disease resistance genes against them in crops.

PubMed

Bae, Chungyun; Han, Sang Wook; Song, Yu-Rim; Kim, Bo-Young; Lee, Hyung-Jin; Lee, Je-Min; Yeam, Inhwa; Heu, Sunggi; Oh, Chang-Sik

2015-07-01

Disease resistance against xylem-colonizing pathogenic bacteria in crops. Plant pathogenic bacteria cause destructive diseases in many commercially important crops. Among these bacteria, eight pathogens, Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, Erwinia amylovora, Pantoea stewartii subsp. stewartii, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. actinidiae, and Xylella fastidiosa, infect their host plants through different infection sites and paths and eventually colonize the xylem tissues of their host plants, resulting in wilting symptoms by blocking water flow or necrosis of xylem tissues. Noticeably, only a relatively small number of resistant cultivars in major crops against these vascular bacterial pathogens except X. oryzae pv. oryzae have been found or generated so far, although these pathogens threaten productivity of major crops. In this review, we summarize the lifestyles of major xylem-colonizing bacterial pathogens and then discuss the progress of current research on disease resistance controlled by qualitative disease resistance genes or quantitative trait loci against them. Finally, we propose infection processes of xylem-colonizing bacterial pathogens as one of possible reasons for why so few qualitative disease resistance genes against these pathogens have been developed or identified so far in crops.

Pathogen inactivation techniques.

PubMed

Pelletier, J P R; Transue, S; Snyder, E L

2006-01-01

The desire to rid the blood supply of pathogens of all types has led to the development of many technologies aimed at the same goal--eradication of the pathogen(s) without harming the blood cells or generating toxic chemical agents. This is a very ambitious goal, and one that has yet to be achieved. One approach is to shun the 'one size fits all' concept and to target pathogen-reduction agents at the Individual component types. This permits the development of technologies that might be compatible with, for example, plasma products but that would be cytocidal and thus incompatible with platelet concentrates or red blood cell units. The technologies to be discussed include solvent detergent and methylene blue treatments--designed to inactivate plasma components and derivatives; psoralens (S-59--amotosalen) designed to pathogen-reduce units of platelets; and two products aimed at red blood cells, S-303 (a Frale--frangible anchor-linker effector compound) and Inactine (a binary ethyleneimine). A final pathogen-reduction material that might actually allow one material to inactivate all three blood components--riboflavin (vitamin B2)--is also under development. The sites of action of the amotosalen (S-59), the S-303 Frale, Inactine, and riboflavin are all localized in the nucleic acid part of the pathogen. Solvent detergent materials act by dissolving the plasma envelope, thus compromising the integrity of the pathogen membrane and rendering it non-infectious. By disrupting the pathogen's ability to replicate or survive, its infectivity is removed. The degree to which bacteria and viruses are affected by a particular pathogen-reducing technology relates to its Gram-positive or Gram-negative status, to the sporulation characteristics for bacteria, and the presence of lipid or protein envelopes for viruses. Concerns related to photoproducts and other breakdown products of these technologies remain, and the toxicology of pathogen-reduction treatments is a major ongoing area of investigation. Clearly, regulatory agencies have a major role to play in the evaluation of these new technologies. This chapter will cover the several types of pathogen-reduction systems, mechanisms of action, the inactivation efficacy for specific types of pathogens, toxicology of the various systems and the published research and clinical trial data supporting their potential usefulness. Due to the nature of the field, pathogen reduction is a work in progress and this review should be considered as a snapshot in time rather than a clear picture of what the future will bring.

Foodborne pathogens in milk and the dairy farm environment: food safety and public health implications.

PubMed

Oliver, S P; Jayarao, B M; Almeida, R A

2005-01-01

Milk and products derived from milk of dairy cows can harbor a variety of microorganisms and can be important sources of foodborne pathogens. The presence of foodborne pathogens in milk is due to direct contact with contaminated sources in the dairy farm environment and to excretion from the udder of an infected animal. Most milk is pasteurized, so why should the dairy industry be concerned about the microbial quality of bulk tank milk? There are several valid reasons, including (1) outbreaks of disease in humans have been traced to the consumption of unpasteurized milk and have also been traced back to pasteurized milk, (2) unpasteurized milk is consumed directly by dairy producers, farm employees, and their families, neighbors, and raw milk advocates, (3) unpasteurized milk is consumed directly by a large segment of the population via consumption of several types of cheeses manufactured from unpasteurized milk, (4) entry of foodborne pathogens via contaminated raw milk into dairy food processing plants can lead to persistence of these pathogens in biofilms, and subsequent contamination of processed milk products and exposure of consumers to pathogenic bacteria, (5) pasteurization may not destroy all foodborne pathogens in milk, and (6) inadequate or faulty pasteurization will not destroy all foodborne pathogens. Furthermore, pathogens such as Listeria monocytogenes can survive and thrive in post-pasteurization processing environments, thus leading to recontamination of dairy products. These pathways pose a risk to the consumer from direct exposure to foodborne pathogens present in unpasteurized dairy products as well as dairy products that become re-contaminated after pasteurization. The purpose of this communication is to review literature published on the prevalence of bacterial foodborne pathogens in milk and in the dairy environment, and to discuss public health and food safety issues associated with foodborne pathogens found in the dairy environment. Information presented supports the model in which the presence of pathogens depends on ingestion of contaminated feed followed by amplification in bovine hosts and fecal dissemination in the farm environment. The final outcome of this cycle is a constantly maintained reservoir of foodborne pathogens that can reach humans by direct contact, ingestion of raw contaminated milk or cheese, or contamination during the processing of milk products. Isolation of bacterial pathogens with similar biotypes from dairy farms and from outbreaks of human disease substantiates this hypothesis.

Methods for detecting pathogens in the beef food chain: detecting particular pathogens

USDA-ARS?s Scientific Manuscript database

The main food-borne pathogens of concern in the beef food chain are Shiga toxin-producing Escherichia coli (STEC) and Salmonella spp.; however, the presence of other pathogens, including Listeria monocytogenes, Campylobacter spp., Clostridium spp., Bacillus cereus, and Mycobacterium avium subsp. par...

76 FR 24793 - Highly Pathogenic Avian Influenza

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-03

.... APHIS-2006-0074] RIN 0579-AC36 Highly Pathogenic Avian Influenza AGENCY: Animal and Plant Health... any subtype of highly pathogenic avian influenza is considered to exist. The interim rule also imposed... avian influenza, or that have moved through regions where any subtype of highly pathogenic avian...

Pathogen profiling for disease management and surveillance.

PubMed

Sintchenko, Vitali; Iredell, Jonathan R; Gilbert, Gwendolyn L

2007-06-01

The usefulness of rapid pathogen genotyping is widely recognized, but its effective interpretation and application requires integration into clinical and public health decision-making. How can pathogen genotyping data best be translated to inform disease management and surveillance? Pathogen profiling integrates microbial genomics data into communicable disease control by consolidating phenotypic identity-based methods with DNA microarrays, proteomics, metabolomics and sequence-based typing. Sharing data on pathogen profiles should facilitate our understanding of transmission patterns and the dynamics of epidemics.

Multiplex detection of agricultural pathogens

DOEpatents

McBride, Mary Teresa; Slezak, Thomas Richard; Messenger, Sharon Lee

2010-09-14

Described are kits and methods useful for detection of seven agricultural pathogens (BPSV; BHV; BVD; FMDV; BTV; SVD; and VESV) in a sample. Genomic sequence information from 7 agricultural pathogens was analyzed to identify signature sequences, e.g., polynucleotide sequences useful for confirming the presence or absence of a pathogen in a sample. Primer and probe sets were designed and optimized for use in a PCR based, multiplexed Luminex assay to successfully identify the presence or absence of pathogens in a sample.

Human and bovine viruses and bacteria at three Great Lakes beaches: Environmental variable associations and health risk

USGS Publications Warehouse

Corsi, Steven R.; Borchardt, Mark A.; Carvin, Rebecca B.; Burch, Tucker R; Spencer, Susan K.; Lutz, Michelle A.; McDermott, Colleen M.; Busse, Kimberly M.; Kleinheinz, Gregory; Feng, Xiaoping; Zhu, Jun

2016-01-01

Waterborne pathogens were measured at three beaches in Lake Michigan, environmental factors for predicting pathogen concentrations were identified, and the risk of swimmer infection and illness was estimated. Waterborne pathogens were detected in 96% of samples collected at three Lake Michigan beaches in summer, 2010. Samples were quantified for 22 pathogens in four microbial categories (human viruses, bovine viruses, protozoa, and pathogenic bacteria). All beaches had detections of human and bovine viruses and pathogenic bacteria indicating influence of multiple contamination sources at these beaches. Occurrence ranged from 40 to 87% for human viruses, 65–87% for pathogenic bacteria, and 13–35% for bovine viruses. Enterovirus, adenovirus A, Salmonella spp., Campylobacter jejuni, bovine polyomavirus, and bovine rotavirus A were present most frequently. Variables selected in multiple regression models used to explore environmental factors that influence pathogens included wave direction, cloud cover, currents, and water temperature. Quantitative Microbial Risk Assessment was done for C. jejuni, Salmonella spp., and enteroviruses to estimate risk of infection and illness. Median infection risks for one-time swimming events were approximately 3 × 10–5, 7 × 10–9, and 3 × 10–7 for C. jejuni, Salmonella spp., and enteroviruses, respectively. Results highlight the importance of investigating multiple pathogens within multiple categories to avoid underestimating the prevalence and risk of waterborne pathogens.

An INCA model for pathogens in rivers and catchments: Model structure, sensitivity analysis and application to the River Thames catchment, UK.

PubMed

Whitehead, P G; Leckie, H; Rankinen, K; Butterfield, D; Futter, M N; Bussi, G

2016-12-01

Pathogens are an ongoing issue for catchment water management and quantifying their transport, loss and potential impacts at key locations, such as water abstractions for public supply and bathing sites, is an important aspect of catchment and coastal management. The Integrated Catchment Model (INCA) has been adapted to model the sources and sinks of pathogens and to capture the dominant dynamics and processes controlling pathogens in catchments. The model simulates the stores of pathogens in soils, sediments, rivers and groundwaters and can account for diffuse inputs of pathogens from agriculture, urban areas or atmospheric deposition. The model also allows for point source discharges from intensive livestock units or from sewage treatment works or any industrial input to river systems. Model equations are presented and the new pathogens model has been applied to the River Thames in order to assess total coliform (TC) responses under current and projected future land use. A Monte Carlo sensitivity analysis indicates that the input coliform estimates from agricultural sources and decay rates are the crucial parameters controlling pathogen behaviour. Whilst there are a number of uncertainties associated with the model that should be accounted for, INCA-Pathogens potentially provides a useful tool to inform policy decisions and manage pathogen loading in river systems. Copyright © 2016. Published by Elsevier B.V.

Rapid emergence of pathogens in agro-ecosystems: global threats to agricultural sustainability and food security.

PubMed

McDonald, Bruce A; Stukenbrock, Eva H

2016-12-05

Agricultural ecosystems are composed of genetically depauperate populations of crop plants grown at a high density and over large spatial scales, with the regional composition of crop species changing little from year to year. These environments are highly conducive for the emergence and dissemination of pathogens. The uniform host populations facilitate the specialization of pathogens to particular crop cultivars and allow the build-up of large population sizes. Population genetic and genomic studies have shed light on the evolutionary mechanisms underlying speciation processes, adaptive evolution and long-distance dispersal of highly damaging pathogens in agro-ecosystems. These studies document the speed with which pathogens evolve to overcome crop resistance genes and pesticides. They also show that crop pathogens can be disseminated very quickly across and among continents through human activities. In this review, we discuss how the peculiar architecture of agro-ecosystems facilitates pathogen emergence, evolution and dispersal. We present four example pathosystems that illustrate both pathogen specialization and pathogen speciation, including different time frames for emergence and different mechanisms underlying the emergence process. Lastly, we argue for a re-design of agro-ecosystems that embraces the concept of dynamic diversity to improve their resilience to pathogens. This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Author(s).

Understanding Virulence in the Brucellae and Francisellae: Towards Efficacious Treatments for Two Potential Biothreat Agents

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

Rasley, A; Parsons, D A; El-Etr, S

2009-12-30

Francisella tularensis, Yersinia pestis and Brucellae species are highly infectious pathogens classified as select agents by the Centers for Disease Control and Prevention (CDC) with the potential for use in bioterrorism attacks. These organisms are known to be facultative intracellular pathogens that preferentially infect human monocytes. As such, understanding how the host responds to infection with these organisms is paramount in detecting and combating human disease. We have compared the ability of fully virulent strains of each pathogen and their non-pathogenic near neighbors to enter and survive inside the human monocytic cell line THP-1 and have quantified the cellular responsemore » to infection with the goal of identifying both unique and common host response patterns. We expanded the scope of these studies to include experiments with pathogenic and non-pathogenic strains of Y. pestis, the causative agent of plague. Nonpathogenic strains of each organism were impaired in their ability to survive intracellularly compared with their pathogenic counterparts. Furthermore, infection of THP-1 cells with pathogenic strains of Y. pestis and F. tularensis resulted in marked increases in the secretion of the inflammatory chemokines IL-8, RANTES, and MIP-1{beta}. In contrast, B. melitensis infection failed to elicit any significant increases in a panel of cytokines tested. These differences may underscore distinct strategies in pathogenic mechanisms employed by these pathogens.« less

Competition for attachment of aquaculture candidate probiotic and pathogenic bacteria on fish intestinal mucus.

PubMed

Vine, N G; Leukes, W D; Kaiser, H; Daya, S; Baxter, J; Hecht, T

2004-06-01

Probiotics for aquaculture are generally only selected by their ability to produce antimicrobial metabolites; however, attachment to intestinal mucus is important in order to remain within the gut of its host. Five candidate probiotics (AP1-AP5), isolated from the clownfish, Amphiprion percula (Lacepéde), were examined for their ability to attach to fish intestinal mucus and compete with two pathogens, Aeromonas hydrophila and Vibrio alginolyticus. Two different radioactive isotopes were used to quantify competition between pathogens and probionts. Attachment of the pathogens was enhanced by the presence of the candidate probiotics. However, the addition of the candidate probiotics after the pathogens resulted in reduced pathogen attachment. Only AP5 caused lower attachment success of V. alginolyticus when added before the pathogen. When AP5 was added first, the average attachment change was 41% compared with 72% when added after V. alginolyticus, suggesting that the probiotic is displaced but that enhanced attachment of the pathogen does not occur. Conversely, when V. alginolyticus was added first, followed by AP5, attachment change was 37% while AP5 had 92% attachment change when added second. This implies that the pathogen was displaced by the candidate probiotic and therefore it appeared that, based on the ability of probiont AP5 to attach to mucus, the growth of the pathogen in the digestive tract might be suppressed by the candidate probiont's presence.

The role of social cognition in parasite and pathogen avoidance.

PubMed

Kavaliers, Martin; Choleris, Elena

2018-07-19

The acquisition and use of social information are integral to social behaviour and parasite/pathogen avoidance. This involves social cognition which encompasses mechanisms for acquiring, processing, retaining and acting on social information. Social cognition entails the acquisition of social information about others (i.e. social recognition) and from others (i.e. social learning). Social cognition involves assessing other individuals and their infection status and the pathogen and parasite threat they pose and deciding about when and how to interact with them. Social cognition provides a framework for examining pathogen and parasite avoidance behaviours and their associated neurobiological mechanisms. Here, we briefly consider the relationships between social cognition and olfactory-mediated pathogen and parasite avoidance behaviours. We briefly discuss aspects of (i) social recognition of actual and potentially infected individuals and the impact of parasite/pathogen threat on mate and social partner choice; (ii) the roles of 'out-groups' (strangers, unfamiliar individuals) and 'in-groups' (familiar individuals) in the expression of parasite/pathogen avoidance behaviours; (iii) individual and social learning, i.e. the utilization of the pathogen recognition and avoidance responses of others; and (iv) the neurobiological mechanisms, in particular the roles of the nonapeptide, oxytocin and steroid hormones (oestrogens) associated with social cognition and parasite/pathogen avoidance.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'. © 2018 The Author(s).

Helminths as vectors of pathogens in vertebrate hosts: a theoretical approach.

PubMed

Perkins, Sarah E; Fenton, Andy

2006-07-01

Pathogens frequently use vectors to facilitate transmission between hosts and, for vertebrate hosts, the vectors are typically ectoparasitic arthropods. However, other parasites that are intimately associated with their hosts may also be ideal candidate vectors; namely the parasitic helminths. Here, we present empirical evidence that helminth vectoring of pathogens occurs in a range of vertebrate systems by a variety of helminth taxa. Using a novel theoretical framework we explore the dynamics of helminth vectoring and determine which host-helminth-pathogen characteristics may favour the evolution of helminth vectoring. We use two theoretical models: the first is a population dynamic model amalgamated from standard macro- and microparasite models, which serves as a framework for investigation of within-host interactions between co-infecting pathogens and helminths. The second is an evolutionary model, which we use to predict the ecological conditions under which we would expect helminth vectoring to evolve. We show that, like arthropod vectors, helminth vectors increase pathogen fitness. However, unlike arthropod vectors, helminth vectoring increases the pathogenic impact on the host and may allow the evolution of high pathogen virulence. We show that concomitant infection of a host with a helminth and pathogen are not necessarily independent of one another, due to helminth vectoring of microparasites, with profound consequences for pathogen persistence and the impact of disease on the host population.

Impacts of climate change on indirect human exposure to pathogens and chemicals from agriculture.

PubMed

Boxall, Alistair B A; Hardy, Anthony; Beulke, Sabine; Boucard, Tatiana; Burgin, Laura; Falloon, Peter D; Haygarth, Philip M; Hutchinson, Thomas; Kovats, R Sari; Leonardi, Giovanni; Levy, Leonard S; Nichols, Gordon; Parsons, Simon A; Potts, Laura; Stone, David; Topp, Edward; Turley, David B; Walsh, Kerry; Wellington, Elizabeth M H; Williams, Richard J

2009-04-01

Climate change is likely to affect the nature of pathogens and chemicals in the environment and their fate and transport. Future risks of pathogens and chemicals could therefore be very different from those of today. In this review, we assess the implications of climate change for changes in human exposures to pathogens and chemicals in agricultural systems in the United Kingdom and discuss the subsequent effects on health impacts. In this review, we used expert input and considered literature on climate change; health effects resulting from exposure to pathogens and chemicals arising from agriculture; inputs of chemicals and pathogens to agricultural systems; and human exposure pathways for pathogens and chemicals in agricultural systems. We established the current evidence base for health effects of chemicals and pathogens in the agricultural environment; determined the potential implications of climate change on chemical and pathogen inputs in agricultural systems; and explored the effects of climate change on environmental transport and fate of different contaminant types. We combined these data to assess the implications of climate change in terms of indirect human exposure to pathogens and chemicals in agricultural systems. We then developed recommendations on future research and policy changes to manage any adverse increases in risks. Overall, climate change is likely to increase human exposures to agricultural contaminants. The magnitude of the increases will be highly dependent on the contaminant type. Risks from many pathogens and particulate and particle-associated contaminants could increase significantly. These increases in exposure can, however, be managed for the most part through targeted research and policy changes.

Pathogen Decontamination of Food Crop Soil: A Review.

PubMed

Gurtler, Joshua B

2017-09-01

The purpose of this review is to delineate means of decontaminating soil. This information might be used to mitigate soil-associated risks of foodborne pathogens. The majority of the research in the published literature involves inactivation of plant pathogens in soil, i.e., those pathogens harmful to fruit and vegetable production and ornamental plants. Very little has been published regarding the inactivation of foodborne human pathogens in crop soil. Nevertheless, because decontamination techniques for plant pathogens might also be useful methods for eliminating foodborne pathogens, this review also includes inactivation of plant pathogens, with appropriate discussion and comparisons, in the hopes that these methods may one day be validated against foodborne pathogens. Some of the major soil decontamination methods that have been investigated and are covered include chemical decontamination (chemigation), solarization, steaming, biofumigation, bacterial competitive exclusion, torch flaming, microwave treatment, and amendment with biochar. Other innovative means of inactivating foodborne pathogens in soils may be discovered and explored in the future, provided that these techniques are economically feasible in terms of chemicals, equipment, and labor. Food microbiology and food safety researchers should reach out to soil scientists and plant pathologists to create links where they do not currently exist and strengthen relationships where they do exist to take advantage of multidisciplinary skills. In time, agricultural output and the demand for fresh produce will increase. With advances in the sensitivity of pathogen testing and epidemiological tracebacks, the need to mitigate preharvest bacterial contamination of fresh produce will become paramount. Hence, soil decontamination technologies may become more economically feasible and practical in light of increasing the microbial safety of fresh produce.

The Tick Microbiome: Why Non-pathogenic Microorganisms Matter in Tick Biology and Pathogen Transmission

PubMed Central

Bonnet, Sarah I.; Binetruy, Florian; Hernández-Jarguín, Angelica M.; Duron, Olivier

2017-01-01

Ticks are among the most important vectors of pathogens affecting humans and other animals worldwide. They do not only carry pathogens however, as a diverse group of commensal and symbiotic microorganisms are also present in ticks. Unlike pathogens, their biology and their effect on ticks remain largely unexplored, and are in fact often neglected. Nonetheless, they can confer multiple detrimental, neutral, or beneficial effects to their tick hosts, and can play various roles in fitness, nutritional adaptation, development, reproduction, defense against environmental stress, and immunity. Non-pathogenic microorganisms may also play a role in driving transmission of tick-borne pathogens (TBP), with many potential implications for both human and animal health. In addition, the genetic proximity of some pathogens to mutualistic symbionts hosted by ticks is evident when studying phylogenies of several bacterial genera. The best examples are found within members of the Rickettsia, Francisella, and Coxiella genera: while in medical and veterinary research these bacteria are traditionally recognized as highly virulent vertebrate pathogens, it is now clear to evolutionary ecologists that many (if not most) Coxiella, Francisella, and Rickettsia bacteria are actually non-pathogenic microorganisms exhibiting alternative lifestyles as mutualistic ticks symbionts. Consequently, ticks represent a compelling yet challenging system in which to study microbiomes and microbial interactions, and to investigate the composition, functional, and ecological implications of bacterial communities. Ultimately, deciphering the relationships between tick microorganisms as well as tick symbiont interactions will garner invaluable information, which may aid in the future development of arthropod pest and vector-borne pathogen transmission control strategies. PMID:28642842

The Tick Microbiome: Why Non-pathogenic Microorganisms Matter in Tick Biology and Pathogen Transmission.

PubMed

Bonnet, Sarah I; Binetruy, Florian; Hernández-Jarguín, Angelica M; Duron, Olivier

2017-01-01

Ticks are among the most important vectors of pathogens affecting humans and other animals worldwide. They do not only carry pathogens however, as a diverse group of commensal and symbiotic microorganisms are also present in ticks. Unlike pathogens, their biology and their effect on ticks remain largely unexplored, and are in fact often neglected. Nonetheless, they can confer multiple detrimental, neutral, or beneficial effects to their tick hosts, and can play various roles in fitness, nutritional adaptation, development, reproduction, defense against environmental stress, and immunity. Non-pathogenic microorganisms may also play a role in driving transmission of tick-borne pathogens (TBP), with many potential implications for both human and animal health. In addition, the genetic proximity of some pathogens to mutualistic symbionts hosted by ticks is evident when studying phylogenies of several bacterial genera. The best examples are found within members of the Rickettsia, Francisella , and Coxiella genera: while in medical and veterinary research these bacteria are traditionally recognized as highly virulent vertebrate pathogens, it is now clear to evolutionary ecologists that many (if not most) Coxiella, Francisella , and Rickettsia bacteria are actually non-pathogenic microorganisms exhibiting alternative lifestyles as mutualistic ticks symbionts. Consequently, ticks represent a compelling yet challenging system in which to study microbiomes and microbial interactions, and to investigate the composition, functional, and ecological implications of bacterial communities. Ultimately, deciphering the relationships between tick microorganisms as well as tick symbiont interactions will garner invaluable information, which may aid in the future development of arthropod pest and vector-borne pathogen transmission control strategies.

Inactivation of bacterial pathogenic load in compost against vermicompost of organic solid waste aiming to achieve sanitation goals: A review.

PubMed

Soobhany, Nuhaa; Mohee, Romeela; Garg, Vinod Kumar

2017-06-01

Waste management strategies for organic residues, such as composting and vermicomposting, have been implemented in some developed and developing countries to solve the problem of organic solid waste (OSW). Yet, these biological treatment technologies do not always result in good quality compost or vermicompost with regards to sanitation capacity owing to the presence of bacterial pathogenic substances in objectionable concentrations. The presence of pathogens in soil conditioners poses a potential health hazard and their occurrence is of particular significance in composts and/or vermicomposts produced from organic materials. Past and present researches demonstrated a high-degree of agreement that various pathogens survive after the composting of certain OSW but whether similar changes in bacterial pathogenic loads arise during vermitechnology has not been thoroughly elucidated. This review garners information regarding the status of various pathogenic bacteria which survived or diffused after the composting process compared to the status of these pathogens after the vermicomposting of OSW with the aim of achieving sanitation goals. This work is also indispensable for the specification of compost quality guidelines concerning pathogen loads which would be specific to treatment technology. It was hypothesized that vermicomposting process for OSW can be efficacious in sustaining the existence of pathogenic organisms most specifically; human pathogens under safety levels. In summary, earthworms can be regarded as a way of obliterating pathogenic bacteria from OSW in a manner equivalent to earthworm gut transit mechanism which classifies vermicomposting as a promising sanitation technique in comparison to composting processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative genomics of pathogenic lineages of Vibrio nigripulchritudo identifies virulence-associated traits

PubMed Central

Goudenège, David; Labreuche, Yannick; Krin, Evelyne; Ansquer, Dominique; Mangenot, Sophie; Calteau, Alexandra; Médigue, Claudine; Mazel, Didier; Polz, Martin F; Le Roux, Frédérique

2013-01-01

Vibrio nigripulchritudo is an emerging pathogen of farmed shrimp in New Caledonia and other regions in the Indo-Pacific. The molecular determinants of V. nigripulchritudo pathogenicity are unknown; however, molecular epidemiological studies have suggested that pathogenicity is linked to particular lineages. Here, we performed high-throughput sequencing-based comparative genome analysis of 16 V. nigripulchritudo strains to explore the genomic diversity and evolutionary history of pathogen-containing lineages and to identify pathogen-specific genetic elements. Our phylogenetic analysis revealed three pathogen-containing V. nigripulchritudo clades, including two clades previously identified from New Caledonia and one novel clade comprising putatively pathogenic isolates from septicemic shrimp in Madagascar. The similar genetic distance between the three clades indicates that they have diverged from an ancestral population roughly at the same time and recombination analysis indicates that these genomes have, in the past, shared a common gene pool and exchanged genes. As each contemporary lineage is comprised of nearly identical strains, comparative genomics allowed differentiation of genetic elements specific to shrimp pathogenesis of varying severity. Notably, only a large plasmid present in all highly pathogenic (HP) strains encodes a toxin. Although less/non-pathogenic strains contain related plasmids, these are differentiated by a putative toxin locus. Expression of this gene by a non-pathogenic V. nigripulchritudo strain resulted in production of toxic culture supernatant, normally an exclusive feature of HP strains. Thus, this protein, here termed ‘nigritoxin', is implicated to an extent that remains to be precisely determined in the toxicity of V. nigripulchritudo. PMID:23739050

Smoking and periodontal disease: discrimination of antibody responses to pathogenic and commensal oral bacteria.

PubMed

Hayman, L; Steffen, M J; Stevens, J; Badger, E; Tempro, P; Fuller, B; McGuire, A; Al-Sabbagh, Mohanad; Thomas, M V; Ebersole, J L

2011-04-01

Smoking is an independent risk factor for the initiation, extent and severity of periodontal disease. This study examined the ability of the host immune system to discriminate commensal oral bacteria from pathogens at mucosal surfaces, i.e. oral cavity. Serum immunoglobulin (Ig)G antibody reactive with three pathogenic and five commensal oral bacteria in 301 current smokers (age range 21-66 years) were examined by enzyme-linked immunosorbent assay. Clinical features of periodontal health were used as measures of periodontitis. Antibody to the pathogens and salivary cotinine levels were related positively to disease severity; however, the antibody levels were best described by the clinical disease unrelated to the amount of smoking. The data showed a greater immune response to pathogens than commensals that was related specifically to disease extent, and most noted in black males. Significant correlations in individual patient responses to the pathogens and commensals were lost with an increasing extent of periodontitis and serum antibody to the pathogens. Antibody to Porphyromonas gingivalis was particularly distinct with respect to the discriminatory nature of the immune responses in recognizing the pathogens. Antibody responses to selected pathogenic and commensal oral microorganisms differed among racial groups and genders. The antibody response to the pathogens was related to disease severity. The level of antibody to the pathogens, and in particular P. gingivalis, was correlated with disease severity in black and male subsets of patients. The amount of smoking did not appear to impact directly serum antibody levels to these oral bacteria. © 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.

Yeast pro- and paraprobiotics have the capability to bind pathogenic bacteria associated with animal disease

USDA-ARS?s Scientific Manuscript database

Live yeast probiotics and yeast cell wall components (paraprobiotics) may serve as an alternative to the use of antibiotics in prevention and treatment of infections caused by pathogenic bacteria. Probiotics and paraprobiotics can bind directly to pathogens, which limits binding of the pathogens to ...

A Novel Receptor-Like Kinase Involved in Fungal Pathogen Defense in Arabidopsis thaliana

USDA-ARS?s Scientific Manuscript database

Plants are under constant attack from a variety of disease causing organisms. Lacking an adaptive immune system, plants repel pathogen attack via an array of pathogen recognition machinery. Receptor-like kinases (RLKs) are involved in the recognition of pathogen-associated molecular patterns (PAMPs)...

A virulent babesia bovis strain failed to infect white-tailed deer (Odocoileus virginianus)

USDA-ARS?s Scientific Manuscript database

Wildlife are an important component in the vector-host-pathogen triangle of livestock diseases, as they maintain biological vectors that transmit pathogens and can serve as reservoirs for such infectious pathogens. Babesia bovis is a tick-borne pathogen, vectored by cattle fever ticks, Rhipicephalus...

Hydrologic, land cover and seasonal patterns of waterborne pathogens in great lakes tributaries

USDA-ARS?s Scientific Manuscript database

Great Lakes tributaries deliver waterborne pathogens from a host of sources. To examine the hydrologic, land cover, and seasonal variability of waterborne pathogens, protozoa (2), pathogenic bacteria (4) and human (8) and bovine (8) viruses from eight rivers were monitored in the Great Lakes watersh...

Highly pathogenic avian influenza A(H7N9) virus, Tennessee, USA, March 2017

USDA-ARS?s Scientific Manuscript database

In March 2017, highly pathogenic avian influenza A(H7N9) was detected at 2 poultry farms in Tennessee, USA. Surveillance data and genetic analyses indicated multiple introductions of low pathogenicity avian influenza virus before mutation to high pathogenicity and interfarm transmission. Poultry sur...

Visualizing pathogen internalization pathways in fresh tomatoes using MicroCT and confocal laser scanning microscopy

USDA-ARS?s Scientific Manuscript database

Pathogen contamination of fresh produce significantly impacts public health and the produce industry's economic well-being. In tomato fruits, studies have shown that the stem-scar plays an important role in pathogen infiltration. However, the exact mechanisms and pathways for pathogen movement insi...

List of New Names of Plant Pathogenic Bacteria (2008-2010)

USDA-ARS?s Scientific Manuscript database

In 2010 the International Society of Plant Pathology Committee on the Taxonomy of Plant Pathogenic Bacteria published the Comprehensive List of Names of Plant Pathogenic Bacteria, 1980-2007 to provide an authoritative register of names of plant pathogens. In this manuscript we up-date the list of na...

Anaplasma marginale superinfection attributable to pathogen strains with distinct genomic backgrounds.

USDA-ARS?s Scientific Manuscript database

Microbial strain structure is dynamic over space and time; shifts in pathogen strain structure result in changing patterns of disease. The scale of change in space and time differs markedly among pathogens depending on multiple factors including pathogen-specific mechanisms of genetic change and the...

Host-pathogen interactions: A cholera surveillance system

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

Wright, Aaron T.

2016-02-22

Bacterial pathogen-secreted proteases may play a key role in inhibiting a potentially widespread host-pathogen interaction. Activity-based protein profiling enabled the identification of a major Vibrio cholerae serine protease that limits the ability of a host-derived intestinal lectin to bind to the bacterial pathogen in vivo.

Correlation between Tick Density and Pathogen Endemicity, New Hampshire

PubMed Central

Walk, Seth T.; Xu, Guang; Stull, Jason W.

2009-01-01

To assess the endemicity of tick-borne pathogens in New Hampshire, we surveyed adult tick vectors. Pathogens were more prevalent in areas of high tick density, suggesting a correlation between tick establishment and pathogen endemicity. Infection rates in ticks correlated with disease frequency in humans. PMID:19331738

75 FR 76492 - Bloodborne Pathogens Standard; Extension of the Office of Management and Budget's (OMB) Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-08

...] Bloodborne Pathogens Standard; Extension of the Office of Management and Budget's (OMB) Approval of... Pathogens Standard (29 CFR 1910.1030). The information collection requirements specified in the Bloodborne Pathogens Standard provides employers and workers with means to provide protection from adverse health...

Host-pathogen interactions and genome evolution in two generalist and specialist microsporidian pathogens of mosquitoes

USDA-ARS?s Scientific Manuscript database

The adaptation of two distantly related microsporidia to their mosquito hosts was investigated. Edhazardia aedis is a specialist pathogen that infects Aedes aegypti, the main vector of dengue and yellow fever arboviruses. Vavraia culicis is a generalist pathogen of several insects including Anophele...

The bacterial microbiome of dermacentor andersoni ticks influences pathogen susceptibility

USDA-ARS?s Scientific Manuscript database

Ticks are of medical and veterinary importance due to their ability to transmit pathogens to humans and animals. The Rocky Mountain wood tick, Dermacentor andersoni, is a vector of a number of pathogens, including Anaplasma marginale, which is the most widespread tick-borne pathogen of livestock. Al...

Pathogen propagation in cultured three-dimensional tissue mass

NASA Technical Reports Server (NTRS)

Wolf, David A. (Inventor); Spaulding, Glenn F. (Inventor); Goodwin, Thomas J. (Inventor)

2000-01-01

A process for propagating a pathogen in a three-dimensional tissue mass cultured at microgravity conditions in a culture vessel containing culture media and a culture matrix is provided. The three-dimensional tissue mass is inoculated with a pathogen and pathogen replication in the cells of the tissue mass achieved.

Detection of hepatitis E virus and other livestock-related pathogens in Iowa streams

USDA-ARS?s Scientific Manuscript database

Manure application is a major source of pathogens to the environment. Through overland runoff and tile drainage, these pathogens contaminate surface water and stream bed sediment. Some of these pathogens are zoonotic that can potentially affect both animal and human health. This study examined the p...

[Principles of management in biological infections].

PubMed

Płusa, Tadeusz

2012-11-01

The effectiveness of the management in respiratory infection is depending on the nature of the biological pathogen and the immune status of the patient. For this reason, providing assistance to victims the organ function support, similarly as defining the pathogen and targeted antibiotic therapy should be applied. Available diagnostic tests provide rapid ability to identify the pathogen and antibiotics are able to control infection. Lack of efficacy of treatment may indicate the diversity of the pathogen than previously known and raises suspicion of biological warfare pathogen.

Antibody-based vaccine strategies against intracellular pathogens.

PubMed

Casadevall, Arturo

2018-04-25

Historically, antibody-mediated immunity was considered effective against toxins, extracellular pathogens and viruses, while control of intracellular pathogens was the domain of cellular immunity. However, numerous observations in recent decades have conclusively shown that antibody can protect against intracellular pathogens. This paradigmatic shift has tremendous implications for immunology and vaccine design. For immunology the observation that antibody can protect against intracellular pathogens has led to the discovery of new mechanisms of antibody action. For vaccine design the knowledge that humoral immunity can be effective in protection means that the knowledge acquired in more than a century of antibody studies can be applied to make new vaccines against this class of pathogens. Copyright © 2018 Elsevier Ltd. All rights reserved.

Insight of Genus Corynebacterium: Ascertaining the Role of Pathogenic and Non-pathogenic Species

PubMed Central

Oliveira, Alberto; Oliveira, Leticia C.; Aburjaile, Flavia; Benevides, Leandro; Tiwari, Sandeep; Jamal, Syed B.; Silva, Arthur; Figueiredo, Henrique C. P.; Ghosh, Preetam; Portela, Ricardo W.; De Carvalho Azevedo, Vasco A.; Wattam, Alice R.

2017-01-01

This review gathers recent information about genomic and transcriptomic studies in the Corynebacterium genus, exploring, for example, prediction of pathogenicity islands and stress response in different pathogenic and non-pathogenic species. In addition, is described several phylogeny studies to Corynebacterium, exploring since the identification of species until biological speciation in one species belonging to the genus Corynebacterium. Important concepts associated with virulence highlighting the role of Pld protein and Tox gene. The adhesion, characteristic of virulence factor, was described using the sortase mechanism that is associated to anchorage to the cell wall. In addition, survival inside the host cell and some diseases, were too addressed for pathogenic corynebacteria, while important biochemical pathways and biotechnological applications retain the focus of this review for non-pathogenic corynebacteria. Concluding, this review broadly explores characteristics in genus Corynebacterium showing to have strong relevance inside the medical, veterinary, and biotechnology field. PMID:29075239

Epigenetic Mechanisms: An Emerging Player in Plant-Microbe Interactions.

PubMed

Zhu, Qian-Hao; Shan, Wei-Xing; Ayliffe, Michael A; Wang, Ming-Bo

2016-03-01

Plants have developed diverse molecular and cellular mechanisms to cope with a lifetime of exposure to a variety of pathogens. Host transcriptional reprogramming is a central part of plant defense upon pathogen recognition. Recent studies link DNA methylation and demethylation as well as chromatin remodeling by posttranslational histone modifications, including acetylation, methylation, and ubiquitination, to changes in the expression levels of defense genes upon pathogen challenge. Remarkably these inducible defense mechanisms can be primed prior to pathogen attack by epigenetic modifications and this heightened resistance state can be transmitted to subsequent generations by inheritance of these modification patterns. Beside the plant host, epigenetic mechanisms have also been implicated in virulence development of pathogens. This review highlights recent findings and insights into epigenetic mechanisms associated with interactions between plants and pathogens, in particular bacterial and fungal pathogens, and demonstrates the positive role they can have in promoting plant defense.

History of Mosquitoborne Diseases in the United States and Implications for New Pathogens.

PubMed

Moreno-Madriñán, Max J; Turell, Michael

2018-05-01

The introduction and spread of West Nile virus and the recent introduction of chikungunya and Zika viruses into the Americas have raised concern about the potential for various tropical pathogens to become established in North America. A historical analysis of yellow fever and malaria incidences in the United States suggests that it is not merely a temperate climate that keeps these pathogens from becoming established. Instead, socioeconomic changes are the most likely explanation for why these pathogens essentially disappeared from the United States yet remain a problem in tropical areas. In contrast to these anthroponotic pathogens that require humans in their transmission cycle, zoonotic pathogens are only slightly affected by socioeconomic factors, which is why West Nile virus became established in North America. In light of increasing globalization, we need to be concerned about the introduction of pathogens such as Rift Valley fever, Japanese encephalitis, and Venezuelan equine encephalitis viruses.

Pathogenic Gene Screening of Mycobacterium tuberculosis by Literature Data Mining and Information Pathway Enrichment Analysis.

PubMed

Xu, Guangyu; Wen, Simin; Pan, Yuchen; Zhang, Nan; Wang, Yuanyi

2018-05-01

Recent studies have unraveled mutations which have led to changes in the original conformation of functional proteins targeted by frontline drugs against Mycobacterium tuberculosis. These mutations are likely responsible for the emergence of drug-resistant strains of M. tuberculosis. Identification of new therapeutic targets is fundamental to the development of novel anti-TB drugs. Boost evolution analysis of interactome data with use of high-throughput biological experimental technologies provides opportunities for identification of pathogenic genes and for screening out novel therapeutic targets. In this study, we identified 584 proven pathogenic genes of M. tuberculosis and new pathogenic genes via bibliometrics and relevant websites such as PubMed, KEGG, and DOOR websites. We identified 13 new genes that are most likely to be pathogenic. This study may contribute to the discovery of new pathogenic genes and help unravel new functions of known pathogenic genes of M. tuberculosis.

Parallel independent evolution of pathogenicity within the genus Yersinia

PubMed Central

Reuter, Sandra; Connor, Thomas R.; Barquist, Lars; Walker, Danielle; Feltwell, Theresa; Harris, Simon R.; Fookes, Maria; Hall, Miquette E.; Petty, Nicola K.; Fuchs, Thilo M.; Corander, Jukka; Dufour, Muriel; Ringwood, Tamara; Savin, Cyril; Bouchier, Christiane; Martin, Liliane; Miettinen, Minna; Shubin, Mikhail; Riehm, Julia M.; Laukkanen-Ninios, Riikka; Sihvonen, Leila M.; Siitonen, Anja; Skurnik, Mikael; Falcão, Juliana Pfrimer; Fukushima, Hiroshi; Scholz, Holger C.; Prentice, Michael B.; Wren, Brendan W.; Parkhill, Julian; Carniel, Elisabeth; Achtman, Mark; McNally, Alan; Thomson, Nicholas R.

2014-01-01

The genus Yersinia has been used as a model system to study pathogen evolution. Using whole-genome sequencing of all Yersinia species, we delineate the gene complement of the whole genus and define patterns of virulence evolution. Multiple distinct ecological specializations appear to have split pathogenic strains from environmental, nonpathogenic lineages. This split demonstrates that contrary to hypotheses that all pathogenic Yersinia species share a recent common pathogenic ancestor, they have evolved independently but followed parallel evolutionary paths in acquiring the same virulence determinants as well as becoming progressively more limited metabolically. Shared virulence determinants are limited to the virulence plasmid pYV and the attachment invasion locus ail. These acquisitions, together with genomic variations in metabolic pathways, have resulted in the parallel emergence of related pathogens displaying an increasingly specialized lifestyle with a spectrum of virulence potential, an emerging theme in the evolution of other important human pathogens. PMID:24753568

Adult trees cause density-dependent mortality in conspecific seedlings by regulating the frequency of pathogenic soil fungi.

PubMed

Liang, Minxia; Liu, Xubing; Gilbert, Gregory S; Zheng, Yi; Luo, Shan; Huang, Fengmin; Yu, Shixiao

2016-12-01

Negative density-dependent seedling mortality has been widely detected in tropical, subtropical and temperate forests, with soil pathogens as a major driver. Here we investigated how host density affects the composition of soil pathogen communities and consequently influences the strength of plant-soil feedbacks. In field censuses of six 1-ha permanent plots, we found that survival was much lower for newly germinated seedlings that were surrounded by more conspecific adults. The relative abundance of pathogenic fungi in soil increased with increasing conspecific tree density for five of nine tree species; more soil pathogens accumulated around roots where adult tree density was higher, and this greater pathogen frequency was associated with lower seedling survival. Our findings show how tree density influences populations of soil pathogens, which creates plant-soil feedbacks that contribute to community-level and population-level compensatory trends in seedling survival. © 2016 John Wiley & Sons Ltd/CNRS.

Insight of Genus Corynebacterium: Ascertaining the Role of Pathogenic and Non-pathogenic Species.

PubMed

Oliveira, Alberto; Oliveira, Leticia C; Aburjaile, Flavia; Benevides, Leandro; Tiwari, Sandeep; Jamal, Syed B; Silva, Arthur; Figueiredo, Henrique C P; Ghosh, Preetam; Portela, Ricardo W; De Carvalho Azevedo, Vasco A; Wattam, Alice R

2017-01-01

This review gathers recent information about genomic and transcriptomic studies in the Corynebacterium genus, exploring, for example, prediction of pathogenicity islands and stress response in different pathogenic and non-pathogenic species. In addition, is described several phylogeny studies to Corynebacterium , exploring since the identification of species until biological speciation in one species belonging to the genus Corynebacterium . Important concepts associated with virulence highlighting the role of Pld protein and Tox gene. The adhesion, characteristic of virulence factor, was described using the sortase mechanism that is associated to anchorage to the cell wall. In addition, survival inside the host cell and some diseases, were too addressed for pathogenic corynebacteria, while important biochemical pathways and biotechnological applications retain the focus of this review for non-pathogenic corynebacteria. Concluding, this review broadly explores characteristics in genus Corynebacterium showing to have strong relevance inside the medical, veterinary, and biotechnology field.

Pathogen prevalence, group bias, and collectivism in the standard cross-cultural sample.

PubMed

Cashdan, Elizabeth; Steele, Matthew

2013-03-01

It has been argued that people in areas with high pathogen loads will be more likely to avoid outsiders, to be biased in favor of in-groups, and to hold collectivist and conformist values. Cross-national studies have supported these predictions. In this paper we provide new pathogen codes for the 186 cultures of the Standard Cross-Cultural Sample and use them, together with existing pathogen and ethnographic data, to try to replicate these cross-national findings. In support of the theory, we found that cultures in high pathogen areas were more likely to socialize children toward collectivist values (obedience rather than self-reliance). There was some evidence that pathogens were associated with reduced adult dispersal. However, we found no evidence of an association between pathogens and our measures of group bias (in-group loyalty and xenophobia) or intergroup contact.

Pathogen prevalence and abundance in honey bee colonies involved in almond pollination.

PubMed

Cavigli, Ian; Daughenbaugh, Katie F; Martin, Madison; Lerch, Michael; Banner, Katie; Garcia, Emma; Brutscher, Laura M; Flenniken, Michelle L

Honey bees are important pollinators of agricultural crops. Since 2006, US beekeepers have experienced high annual honey bee colony losses, which may be attributed to multiple abiotic and biotic factors, including pathogens. However, the relative importance of these factors has not been fully elucidated. To identify the most prevalent pathogens and investigate the relationship between colony strength and health, we assessed pathogen occurrence, prevalence, and abundance in Western US honey bee colonies involved in almond pollination. The most prevalent pathogens were Black queen cell virus (BQCV), Lake Sinai virus 2 (LSV2), Sacbrood virus (SBV), Nosema ceranae , and trypanosomatids. Our results indicated that pathogen prevalence and abundance were associated with both sampling date and beekeeping operation, that prevalence was highest in honey bee samples obtained immediately after almond pollination, and that weak colonies had a greater mean pathogen prevalence than strong colonies.

Nitric Oxide in the Offensive Strategy of Fungal and Oomycete Plant Pathogens

PubMed Central

Arasimowicz-Jelonek, Magdalena; Floryszak-Wieczorek, Jolanta

2016-01-01

In the course of evolutionary changes pathogens have developed many invasion strategies, to which the host organisms responded with a broad range of defense reactions involving endogenous signaling molecules, such as nitric oxide (NO). There is evidence that pathogenic microorganisms, including two most important groups of eukaryotic plant pathogens, also acquired the ability to synthesize NO via non-unequivocally defined oxidative and/or reductive routes. Although the both kingdoms Chromista and Fungi are remarkably diverse, the experimental data clearly indicate that pathogen-derived NO is an important regulatory molecule controlling not only developmental processes, but also pathogen virulence and its survival in the host. An active control of mitigation or aggravation of nitrosative stress within host cells seems to be a key determinant for the successful invasion of plant pathogens representing different lifestyles and an effective mode of dispersion in various environmental niches. PMID:26973690

Differential immune response of mallard duck peripheral blood mononuclear cells to two highly pathogenic avian influenza H5N1 viruses with distinct pathogenicity in mallard ducks.

PubMed

Cui, Zhu; Hu, Jiao; He, Liang; Li, Qunhui; Gu, Min; Wang, Xiaoquan; Hu, Shunlin; Liu, Huimou; Liu, Wenbo; Liu, Xiaowen; Liu, Xiufan

2014-02-01

CK10 and GS10 are two H5N1 highly pathogenic influenza viruses of similar genetic background but differ in their pathogenicity in mallard ducks. CK10 is highly pathogenic whereas GS10 is low pathogenic. In this study, strong inflammatory response in terms of the expression level of several cytokines was observed in mallard duck peripheral blood mononuclear cells (PBMC) infected with CK10 while mild response was triggered in those by GS10 infection. Two remarkable and intense peaks of immune response were induced by CK10 infection within 24 hours (at 8 and 24 hours post infection, respectively) without reducing the virus replication. Our observations indicated that sustained and intense innate immune responses may be central to the high pathogenicity caused by CK10 in ducks.

Maize-Pathogen Interactions: An Ongoing Combat from a Proteomics Perspective.

PubMed

Pechanova, Olga; Pechan, Tibor

2015-11-30

Maize (Zea mays L.) is a host to numerous pathogenic species that impose serious diseases to its ear and foliage, negatively affecting the yield and the quality of the maize crop. A considerable amount of research has been carried out to elucidate mechanisms of maize-pathogen interactions with a major goal to identify defense-associated proteins. In this review, we summarize interactions of maize with its agriculturally important pathogens that were assessed at the proteome level. Employing differential analyses, such as the comparison of pathogen-resistant and susceptible maize varieties, as well as changes in maize proteomes after pathogen challenge, numerous proteins were identified as possible candidates in maize resistance. We describe findings of various research groups that used mainly mass spectrometry-based, high through-put proteomic tools to investigate maize interactions with fungal pathogens Aspergillus flavus, Fusarium spp., and Curvularia lunata, and viral agents Rice Black-streaked Dwarf Virus and Sugarcane Mosaic Virus.

Maize-Pathogen Interactions: An Ongoing Combat from a Proteomics Perspective

PubMed Central

Pechanova, Olga; Pechan, Tibor

2015-01-01

Maize (Zea mays L.) is a host to numerous pathogenic species that impose serious diseases to its ear and foliage, negatively affecting the yield and the quality of the maize crop. A considerable amount of research has been carried out to elucidate mechanisms of maize-pathogen interactions with a major goal to identify defense-associated proteins. In this review, we summarize interactions of maize with its agriculturally important pathogens that were assessed at the proteome level. Employing differential analyses, such as the comparison of pathogen-resistant and susceptible maize varieties, as well as changes in maize proteomes after pathogen challenge, numerous proteins were identified as possible candidates in maize resistance. We describe findings of various research groups that used mainly mass spectrometry-based, high through-put proteomic tools to investigate maize interactions with fungal pathogens Aspergillus flavus, Fusarium spp., and Curvularia lunata, and viral agents Rice Black-streaked Dwarf Virus and Sugarcane Mosaic Virus. PMID:26633370

Electron beam inactivation of selected microbial pathogens and indicator organisms in aerobically and anaerobically digested sewage sludge.

PubMed

Praveen, Chandni; Jesudhasan, Palmy R; Reimers, Robert S; Pillai, Suresh D

2013-09-01

Microbial pathogens in municipal sewage sludges need to be inactivated prior to environmental disposal. The efficacy of high energy (10 MeV) e-beam irradiation to inactivate a variety of selected microbial pathogens and indicator organisms in aerobically and anaerobically digested sewage sludge was evaluated. Both bacterial and viral pathogens and indicator organisms are susceptible to e-beam irradiation. However, as expected there was a significant difference in their respective e-beam irradiation sensitivity. Somatic coliphages, bacterial endospores and enteric viruses were more resistant compared to bacterial pathogens. The current US EPA mandated 10 kGy minimum dose was capable of achieving significant reduction of both bacterial and viral pathogens. Somatic coliphages can be used as a microbial indicator for monitoring e-beam processes in terms of pathogen inactivation in sewage sludges. Copyright © 2013 Elsevier Ltd. All rights reserved.

Detection of Microbial Water Quality Indicators and Fecal Waterborne Pathogens in Environmental Waters: A Review of Methods, Applications, and Limitations

EPA Science Inventory

Environmental waters are important reservoirs of pathogenic microorganisms, many of which are of fecal origin. In most cases, the presence of pathogens is determined using surrogate bacterial indicators. In other cases, direct detection of the pathogen in question is required. M...

Quantitative Differences in Salivary Pathogen Load during Tick Transmission Underlie Strain-Specific Variation in Transmission Efficiency of Anaplasma marginale

USDA-ARS?s Scientific Manuscript database

The relative fitness of arthropod-borne pathogens within the vector can be a major determinant of pathogen prevalence within the mammalian host population. Strains of the tick-borne rickettsia Anaplasma marginale differ markedly in transmission efficiency with consequent impact on pathogen strain st...

Enteric pathogens and gut function: role of cytokines and STATs

USDA-ARS?s Scientific Manuscript database

The gut harbors the largest immune system in the body. The mucosa is considered to be the initial site of interaction with commensal and pathogenic organisms; therefore, it is the first line of defense against pathogens. In response to the invasion of various pathogens, naïve CD4+ cells differenti...

Method for genetic identification of unknown organisms

DOEpatents

Colston, Jr., Billy W.; Fitch, Joseph P.; Hindson, Benjamin J.; Carter, Chance J.; Beer, Neil Reginald

2016-08-23

A method of rapid, genome and proteome based identification of unknown pathogenic or non-pathogenic organisms in a complex sample. The entire sample is analyzed by creating millions of emulsion encapsulated microdroplets, each containing a single pathogenic or non-pathogenic organism sized particle and appropriate reagents for amplification. Following amplification, the amplified product is analyzed.

Soil moisture mediated interaction between Polygonatum biflorum and leaf spot disease

Treesearch

Robert J. II Warren; Erin Mordecai

2010-01-01

Fungal pathogens can regulate the abundance and distribution of natural plant populations by inhibiting the growth, survival, and reproduction of their hosts. The abiotic environment is a crucial component in host–pathogen interactions in natural plant populations as favorable conditions drive pathogen development, reproduction, and persistence. Foliar plant pathogens...

Fire effects on the cheatgrass seed bank pathogen Pyrenophora semeniperda

Treesearch

Julie Beckstead; Laura E. Street; Susan E. Meyer; Phil S. Allen

2011-01-01

The generalist fungal pathogen Pyrenophora semeniperda occurs primarily in cheatgrass (Bromus tectorum) seed banks, where it causes high mortality. We investigated the relationship between this pathogen and its cheatgrass host in the context of fire, asking whether burning would facilitate host escape from the pathogen or increase host vulnerability. We used a series...

Medical Surveillance Monthly Report (MSMR). Volume 4, Number 6, September 1998

DTIC Science & Technology

1998-09-01

bacterial pathogens (from both cases and noncases) were Salmonella enteritidis , entero-adherent E. coli (EAEC), entero- toxigenic E. coli (ETEC), and...Isolation rate (% of cultures + for pathogen) No. of cultures + for pathogen Isolation rate (% of cultures + for pathogen) Salmonella enteritidis 32...infections ............. 8 ARD surveillance update .................................................. 13 Foodborne outbreak, Salmonella

Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity

PubMed Central

Ogden, Nick H.; Mechai, Samir; Margos, Gabriele

2013-01-01

The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity. PMID:24010124

Amoeba provide insight into the origin of virulence in pathogenic fungi.

PubMed

Casadevall, Arturo

2012-01-01

Why are some fungi pathogenic while the majority poses no threat to humans or other hosts? Of the more than 1.5 million fungal species only about 150-300 are pathogenic for humans, and of these, only 10-15 are relatively common pathogens. In contrast, fungi are major pathogens for plants and insects. These facts pose several fundamental questions including the mechanisms responsible for the origin of virulence among the few pathogenic species and the high resistance of mammals to fungal diseases. This essay explores the origin of virulences among environmental fungi with no obvious requirement for animal association and proposes that selection pressures by amoeboid predators led to the emergence of traits that can also promote survival in mammalian hosts. In this regard, analysis of the interactions between the human pathogenic funges Cryptococcus neoformans and amoeba have shown a remarkable similarity with the interaction of this fungus with macrophages. Hence the virulence of environmental pathogenic fungi is proposed to originate from a combination of selection by amoeboid predators and perhaps other soil organism with thermal tolerance sufficient to allow survival in mammalian hosts.

Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity.

PubMed

Ogden, Nick H; Mechai, Samir; Margos, Gabriele

2013-01-01

The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R 0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity.

The function of small RNAs in plant biotic stress response.

PubMed

Huang, Juan; Yang, Meiling; Zhang, Xiaoming

2016-04-01

Small RNAs (sRNAs) play essential roles in plants upon biotic stress. Plants utilize RNA silencing machinery to facilitate pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to defend against pathogen attack or to facilitate defense against insect herbivores. Pathogens, on the other hand, are also able to generate effectors and sRNAs to counter the host immune response. The arms race between plants and pathogens/insect herbivores has triggered the evolution of sRNAs, RNA silencing machinery and pathogen effectors. A great number of studies have been performed to investigate the roles of sRNAs in plant defense, bringing in the opportunity to utilize sRNAs in plant protection. Transgenic plants with pathogen-derived resistance ability or transgenerational defense have been generated, which show promising potential as solutions for pathogen/insect herbivore problems in the field. Here we summarize the recent progress on the function of sRNAs in response to biotic stress, mainly in plant-pathogen/insect herbivore interaction, and the application of sRNAs in disease and insect herbivore control. © 2016 Institute of Botany, Chinese Academy of Sciences.

Engineered nanoconstructs for the multiplexed and sensitive detection of high-risk pathogens

NASA Astrophysics Data System (ADS)

Seo, Youngmin; Kim, Ji-Eun; Jeong, Yoon; Lee, Kwan Hong; Hwang, Jangsun; Hong, Jongwook; Park, Hansoo; Choi, Jonghoon

2016-01-01

Many countries categorize the causative agents of severe infectious diseases as high-risk pathogens. Given their extreme infectivity and potential to be used as biological weapons, a rapid and sensitive method for detection of high-risk pathogens (e.g., Bacillus anthracis, Francisella tularensis, Yersinia pestis, and Vaccinia virus) is highly desirable. Here, we report the construction of a novel detection platform comprising two units: (1) magnetic beads separately conjugated with multiple capturing antibodies against four different high-risk pathogens for simple and rapid isolation, and (2) genetically engineered apoferritin nanoparticles conjugated with multiple quantum dots and detection antibodies against four different high-risk pathogens for signal amplification. For each high-risk pathogen, we demonstrated at least 10-fold increase in sensitivity compared to traditional lateral flow devices that utilize enzyme-based detection methods. Multiplexed detection of high-risk pathogens in a sample was also successful by using the nanoconstructs harboring the dye molecules with fluorescence at different wavelengths. We ultimately envision the use of this novel nanoprobe detection platform in future applications that require highly sensitive on-site detection of high-risk pathogens.

AquaPathogen X--A template database for tracking field isolates of aquatic pathogens

USGS Publications Warehouse

Emmenegger, Evi; Kurath, Gael

2012-01-01

AquaPathogen X is a template database for recording information on individual isolates of aquatic pathogens and is available for download from the U.S. Geological Survey (USGS) Western Fisheries Research Center (WFRC) website (http://wfrc.usgs.gov). This template database can accommodate the nucleotide sequence data generated in molecular epidemiological studies along with the myriad of abiotic and biotic traits associated with isolates of various pathogens (for example, viruses, parasites, or bacteria) from multiple aquatic animal host species (for example, fish, shellfish, or shrimp). The simultaneous cataloging of isolates from different aquatic pathogens is a unique feature to the AquaPathogen X database, which can be used in surveillance of emerging aquatic animal diseases and clarification of main risk factors associated with pathogen incursions into new water systems. As a template database, the data fields are empty upon download and can be modified to user specifications. For example, an application of the template database that stores the epidemiological profiles of fish virus isolates, called Fish ViroTrak (fig. 1), was also developed (Emmenegger and others, 2011).

Global analysis of gene expression reveals mRNA superinduction is required for the inducible immune response to a bacterial pathogen

PubMed Central

Barry, Kevin C; Ingolia, Nicholas T; Vance, Russell E

2017-01-01

The inducible innate immune response to infection requires a concerted process of gene expression that is regulated at multiple levels. Most global analyses of the innate immune response have focused on transcription induced by defined immunostimulatory ligands, such as lipopolysaccharide. However, the response to pathogens involves additional complexity, as pathogens interfere with virtually every step of gene expression. How cells respond to pathogen-mediated disruption of gene expression to nevertheless initiate protective responses remains unclear. We previously discovered that a pathogen-mediated blockade of host protein synthesis provokes the production of specific pro-inflammatory cytokines. It remains unclear how these cytokines are produced despite the global pathogen-induced block of translation. We addressed this question by using parallel RNAseq and ribosome profiling to characterize the response of macrophages to infection with the intracellular bacterial pathogen Legionella pneumophila. Our results reveal that mRNA superinduction is required for the inducible immune response to a bacterial pathogen. DOI: http://dx.doi.org/10.7554/eLife.22707.001 PMID:28383283

Effect of United States buckwheat honey on antibiotic-resistant hospital acquired pathogens

PubMed Central

Hammond, Eric Nee-Armah; Duster, Megan; Musuuza, Jackson Ssentalo; Safdar, Nasia

2016-01-01

Introduction Due to an upsurge in antibiotic-resistant infections and lack of therapeutic options, new approaches are needed for treatment. Honey may be one such potential therapeutic option. We investigated the susceptibility of hospital acquired pathogens to four honeys from Wisconsin, United States, and then determined if the antibacterial effect of each honey against these pathogens is primarily due to the high sugar content. Methods Thirteen pathogens including: four Clostridium difficile, two Methicillin-resistant Staphylococcus aureus, two Pseudomonas aeruginosa, one Methicillin-Susceptible Staphylococcus aureus, two Vancomycin-resistance Enterococcus, one Enterococcus faecalis and one Klebsiella pneumoniae were exposed to 1-50% (w/v) four Wisconsin honeys and Artificial honey to determine their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the broth dilution method. Results Buckwheat honey predominantly exhibited a bactericidal mode of action against the tested pathogens, and this varied with each pathogen. C. difficile isolates were more sensitive to the Wisconsin buckwheat honey as compared to the other pathogens. Artificial honey at 50% (w/v) failed to kill any of the pathogens. The high sugar content of Wisconsin buckwheat honey is not the only factor responsible for its bactericidal activity. Conclusion Wisconsin buckwheat honey has the potential to be an important addition to therapeutic armamentarium against resistant pathogens and should be investigated further. PMID:28292167

The membrane as the gatekeeper of infection: Cholesterol in host-pathogen interaction.

PubMed

Kumar, G Aditya; Jafurulla, Md; Chattopadhyay, Amitabha

2016-09-01

The cellular plasma membrane serves as a portal for the entry of intracellular pathogens. An essential step for an intracellular pathogen to gain entry into a host cell therefore is to be able to cross the cell membrane. In this review, we highlight the role of host membrane cholesterol in regulating the entry of intracellular pathogens using insights obtained from work on the interaction of Leishmania and Mycobacterium with host cells. The entry of these pathogens is known to be dependent on host membrane cholesterol. Importantly, pathogen entry is inhibited either upon depletion (or complexation), or enrichment of membrane cholesterol. In other words, an optimum level of host membrane cholesterol is necessary for efficient infection by pathogens. In this overall context, we propose a general mechanism, based on cholesterol-induced conformational changes, involving cholesterol binding sites in host cell surface receptors that are implicated in this process. A therapeutic strategy targeting modulation of membrane cholesterol would have the advantage of avoiding the commonly encountered problem of drug resistance in tackling infection by intracellular pathogens. Insights into the role of host membrane cholesterol in pathogen entry would be instrumental in the development of novel therapeutic strategies to effectively tackle intracellular pathogenesis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

MODELING HOST-PATHOGEN INTERACTIONS: COMPUTATIONAL BIOLOGY AND BIOINFORMATICS FOR INFECTIOUS DISEASE RESEARCH (Session introduction)

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

McDermott, Jason E.; Braun, Pascal; Bonneau, Richard A.

Pathogenic infections are a major cause of both human disease and loss of crop yields and animal stocks and thus cause immense damage to the worldwide economy. The significance of infectious diseases is expected to increase in an ever more connected warming world, in which new viral, bacterial and fungal pathogens can find novel hosts and ecologic niches. At the same time, the complex and sophisticated mechanisms by which diverse pathogenic agents evade defense mechanisms and subvert their hosts networks to suit their lifestyle needs is still very incompletely understood especially from a systems perspective [1]. Thus, understanding host-pathogen interactionsmore » is both an important and a scientifically fascinating topic. Recently, technology has offered the opportunity to investigate host-pathogen interactions on a level of detail and scope that offers immense computational and analytical possibilities. Genome sequencing was pioneered on some of these pathogens, and the number of strains and variants of pathogens sequenced to date vastly outnumbers the number of host genomes available. At the same time, for both plant and human hosts more and more data on population level genomic variation becomes available and offers a rich field for analysis into the genetic interactions between host and pathogen.« less

Evidence for maintenance of sex by pathogens in plants.

PubMed

Busch, Jeremiah W; Neiman, Maurine; Koslow, Jennifer M

2004-11-01

The predominance of outcrossing despite the substantial transmission advantage of self-fertilization remains a paradox. Theory suggests that selection can favor outcrossing if it enables the production of offspring that are less susceptible to pathogen attack than offspring produced via self-fertilization. Thus, if pathogen pressure is contributing to the maintenance of outcrossing in plants, there may be a positive correlation between the number of pathogen species attacking plant species and the outcrossing rate of the plant species. We tested this hypothesis by examining the association between outcrossing rate and the number of fungal pathogen species that attack a large, taxonomically diverse set of seed plants. We show that plant species attacked by more fungal pathogen species have higher outcrossing rates than plants with fewer enemies. This relationship persists after correcting for study bias among natural and agricultural species of plants. We also accounted for the nested hierarchy of relationships among plant lineages by conducting phylogenetically independent contrasts (PICs) within genera and families that were adequately represented in our dataset. A meta-analysis of the correlation between pathogen and outcrossing PICs shows that there is a positive correlation between pathogen species number and outcrossing rates. This pattern is consistent with the hypothesis that pathogen-mediated selection may contribute to the maintenance of outcrossing in species of seed plants.

Evolution of pathogenicity traits in the apple scab fungal pathogen in response to the domestication of its host

PubMed Central

Lê Van, Amandine; Gladieux, Pierre; Lemaire, Christophe; Cornille, Amandine; Giraud, Tatiana; Durel, Charles-Eric; Caffier, Valérie; Le Cam, Bruno

2012-01-01

Understanding how pathogens emerge is essential to bring disease-causing agents under durable human control. Here, we used cross-pathogenicity tests to investigate the changes in life-history traits of the fungal pathogen Venturia inaequalis associated with host-tracking during the domestication of apple and subsequent host-range expansion on the wild European crabapple (Malus sylvestris). Pathogenicity of 40 isolates collected in wild and domesticated ecosystems was assessed on the domesticated apple, its Central Asian main progenitor (M. sieversii) and M. sylvestris. Isolates from wild habitats in the centre of origin of the crop were not pathogenic on the domesticated apple and less aggressive than other isolates on their host of origin. Isolates from the agro-ecosystem in Central Asia infected a higher proportion of plants with higher aggressiveness, on both the domesticated host and its progenitor. Isolates from the European crabapple were still able to cause disease on other species but were less aggressive and less frequently virulent on these hosts than their endemic populations. Our results suggest that the domestication of apple was associated with the acquisition of virulence in the pathogen following host-tracking. The spread of the disease in the agro-ecosystem would also have been accompanied by an increase in overall pathogenicity. PMID:23144656

A theoretical framework for biological control of soil-borne plant pathogens: Identifying effective strategies.

PubMed

Cunniffe, Nik J; Gilligan, Christopher A

2011-06-07

We develop and analyse a flexible compartmental model of the interaction between a plant host, a soil-borne pathogen and a microbial antagonist, for use in optimising biological control. By extracting invasion and persistence thresholds of host, pathogen and biological control agent, performing an equilibrium analysis, and numerical investigation of sensitivity to parameters and initial conditions, we determine criteria for successful biological control. We identify conditions for biological control (i) to prevent a pathogen entering a system, (ii) to eradicate a pathogen that is already present and, if that is not possible, (iii) to reduce the density of the pathogen. Control depends upon the epidemiology of the pathogen and how efficiently the antagonist can colonise particular habitats (i.e. healthy tissue, infected tissue and/or soil-borne inoculum). A sharp transition between totally effective control (i.e. eradication of the pathogen) and totally ineffective control can follow slight changes in biologically interpretable parameters or to the initial amounts of pathogen and biological control agent present. Effective biological control requires careful matching of antagonists to pathosystems. For preventative/eradicative control, antagonists must colonise susceptible hosts. However, for reduction in disease prevalence, the range of habitat is less important than the antagonist's bulking-up efficiency. Copyright © 2011 Elsevier Ltd. All rights reserved.

Arthropods vector grapevine trunk disease pathogens.

PubMed

Moyo, P; Allsopp, E; Roets, F; Mostert, L; Halleen, F

2014-10-01

Arthropod-mediated dispersal of pathogens is known in many cropping systems but has never been demonstrated for grapevine trunk disease pathogens. Arthropods from vineyards were screened for the presence of pathogens associated with Petri disease and esca using cultural and molecular techniques. The ability of the most abundant pathogen-carrying species to inoculate healthy grapevine vascular tissues was also determined. Millipedes and ants were allowed to associate with a DsRed- Express-transformed Phaeomoniella chlamydospora, after which they were exposed to freshly pruned healthy grapevines under controlled conditions and wounds were monitored for subsequent infection. In addition, the possibility of millipede excreta, commonly found on pruning wounds in the field, to act as inoculum source was determined. A diverse arthropod fauna was associated with declining grapevines and many of these carried trunk disease pathogens. However, spiders, the ant Crematogaster peringueyi, and the millipede Ommattoiulus moreleti were the most abundant pathogen carriers. The ant and millipede species fed on pruning wound sap and effectively transmitted trunk disease pathogens. Millipede excreta contained viable spores of Phaeomoniella chlamydospora and may serve as an inoculum source. Numerous arthropods, including beneficial predators, are potential vectors of grapevine trunk disease pathogens. Our results highlight the need for an integrated approach, including targeted management of ants and millipedes at the time of pruning, to limit the spread of grapevine trunk diseases.

The Arabidopsis miR396 mediates pathogen-associated molecular pattern-triggered immune responses against fungal pathogens

PubMed Central

Soto-Suárez, Mauricio; Baldrich, Patricia; Weigel, Detlef; Rubio-Somoza, Ignacio; San Segundo, Blanca

2017-01-01

MicroRNAs (miRNAs) play a pivotal role in regulating gene expression during plant development. Although a substantial fraction of plant miRNAs has proven responsive to pathogen infection, their role in disease resistance remains largely unknown, especially during fungal infections. In this study, we screened Arabidopsis thaliana lines in which miRNA activity has been reduced using artificial miRNA target mimics (MIM lines) for their response to fungal pathogens. Reduced activity of miR396 (MIM396 plants) was found to confer broad resistance to necrotrophic and hemibiotrophic fungal pathogens. MiR396 levels gradually decreased during fungal infection, thus, enabling its GRF (GROWTH-REGULATING FACTOR) transcription factor target genes to trigger host reprogramming. Pathogen resistance in MIM396 plants is based on a superactivation of defense responses consistent with a priming event during pathogen infection. Notably, low levels of miR396 are not translated in developmental defects in absence of pathogen challenge. Our findings support a role of miR396 in regulating plant immunity, and broaden our knowledge about the molecular players and processes that sustain defense priming. That miR396 modulates innate immunity without growth costs also suggests fine-tuning of miR396 levels as an effective biotechnological means for protection against pathogen infection. PMID:28332603

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano

PubMed Central

Banskar, Sunil; Bhute, Shrikant S.; Suryavanshi, Mangesh V.; Punekar, Sachin; Shouche, Yogesh S.

2016-01-01

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals. PMID:27845426

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano.

PubMed

Banskar, Sunil; Bhute, Shrikant S; Suryavanshi, Mangesh V; Punekar, Sachin; Shouche, Yogesh S

2016-11-15

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals.

Mixed infections reveal virulence differences between host-specific bee pathogens.

PubMed

Klinger, Ellen G; Vojvodic, Svjetlana; DeGrandi-Hoffman, Gloria; Welker, Dennis L; James, Rosalind R

2015-07-01

Dynamics of host-pathogen interactions are complex, often influencing the ecology, evolution and behavior of both the host and pathogen. In the natural world, infections with multiple pathogens are common, yet due to their complexity, interactions can be difficult to predict and study. Mathematical models help facilitate our understanding of these evolutionary processes, but empirical data are needed to test model assumptions and predictions. We used two common theoretical models regarding mixed infections (superinfection and co-infection) to determine which model assumptions best described a group of fungal pathogens closely associated with bees. We tested three fungal species, Ascosphaera apis, Ascosphaera aggregata and Ascosphaera larvis, in two bee hosts (Apis mellifera and Megachile rotundata). Bee survival was not significantly different in mixed infections vs. solo infections with the most virulent pathogen for either host, but fungal growth within the host was significantly altered by mixed infections. In the host A. mellifera, only the most virulent pathogen was present in the host post-infection (indicating superinfective properties). In M. rotundata, the most virulent pathogen co-existed with the lesser-virulent one (indicating co-infective properties). We demonstrated that the competitive outcomes of mixed infections were host-specific, indicating strong host specificity among these fungal bee pathogens. Published by Elsevier Inc.

Evolution of pathogen virulence across space during an epidemic

USGS Publications Warehouse

Osnas, Erik; Hurtado, Paul J.; Dobson, Andrew P.

2015-01-01

We explore pathogen virulence evolution during the spatial expansion of an infectious disease epidemic in the presence of a novel host movement trade-off, using a simple, spatially explicit mathematical model. This work is motivated by empirical observations of the Mycoplasma gallisepticum invasion into North American house finch (Haemorhous mexicanus) populations; however, our results likely have important applications to other emerging infectious diseases in mobile hosts. We assume that infection reduces host movement and survival and that across pathogen strains the severity of these reductions increases with pathogen infectiousness. Assuming these trade-offs between pathogen virulence (host mortality), pathogen transmission, and host movement, we find that pathogen virulence levels near the epidemic front (that maximize wave speed) are lower than those that have a short-term growth rate advantage or that ultimately prevail (i.e., are evolutionarily stable) near the epicenter and where infection becomes endemic (i.e., that maximize the pathogen basic reproductive ratio). We predict that, under these trade-offs, less virulent pathogen strains will dominate the periphery of an epidemic and that more virulent strains will increase in frequency after invasion where disease is endemic. These results have important implications for observing and interpreting spatiotemporal epidemic data and may help explain transient virulence dynamics of emerging infectious diseases.

Potential in vitro antimicrobial efficacy of Holigarna arnottiana (Hook F).

PubMed

Manilal, Aseer; Idhayadhulla, Akbar

2014-01-01

To explore the in vitro antimicrobial potential of Holigarna arnottiana (H. arnottiana) against human and shrimp pathogenic bacteria and use GC-MS analysis to elucidate its antimicrobial principles. In the present study, organic extract of H. arnottiana was examined for in vitro antimicrobial potency against five clinical human pathogens, seven species of human type culture pathogens, six pathogenic Vibrio strains isolated from moribund tiger shrimp (Penaeus monodon) and seven type cultures (Microbial Type Culture Collection, MTCC) of prominent shrimp pathogens. The extraction of H. arnottiana with ethyl acetate yielded bioactive crude extract that efficiently repressed the growth of all tested pathogens. Among the pathogens tested, shrimp pathogens were the most susceptible organisms while clinical pathogens were found to be a little resistant. The chemical constituents of the H. arnottiana were analysed by GC-MS which revealed the presence of major compounds such as 3,7,11,15-tetramethyl-2-hexadecen-1-o1 (42.1%), 1-lodo-2-methylundecane (34.5%) and squalene (11.1%) which might have a functional role in the chemical defence against microbial invasion. Based on the finding it could be inferred that H. arnottiana would be a reliable source for developing shrimp and human bio-therapeutics in future. Copyright © 2014 Asian Pacific Tropical Biomedical Magazine. Published by Elsevier B.V. All rights reserved.

Potential in vitro antimicrobial efficacy of Holigarna arnottiana (Hook F)

PubMed Central

Manilal, Aseer; Idhayadhulla, Akbar

2014-01-01

Objective To explore the in vitro antimicrobial potential of Holigarna arnottiana (H. arnottiana) against human and shrimp pathogenic bacteria and use GC-MS analysis to elucidate its antimicrobial principles. Methods In the present study, organic extract of H. arnottiana was examined for in vitro antimicrobial potency against five clinical human pathogens, seven species of human type culture pathogens, six pathogenic Vibrio strains isolated from moribund tiger shrimp (Penaeus monodon) and seven type cultures (Microbial Type Culture Collection, MTCC) of prominent shrimp pathogens. Results The extraction of H. arnottiana with ethyl acetate yielded bioactive crude extract that efficiently repressed the growth of all tested pathogens. Among the pathogens tested, shrimp pathogens were the most susceptible organisms while clinical pathogens were found to be a little resistant. The chemical constituents of the H. arnottiana were analysed by GC-MS which revealed the presence of major compounds such as 3,7,11,15-tetramethyl-2-hexadecen-1-o1 (42.1%), 1-lodo-2-methylundecane (34.5%) and squalene (11.1%) which might have a functional role in the chemical defence against microbial invasion. Conclusions Based on the finding it could be inferred that H. arnottiana would be a reliable source for developing shrimp and human bio-therapeutics in future. PMID:24144126

Review of pathogen treatment reductions for onsite non ...

EPA Pesticide Factsheets

Communities face a challenge when implementing onsite reuse of collected waters for non-potable purposes given the lack of national microbial standards. Quantitative Microbial Risk Assessment (QMRA) can be used to predict the pathogen risks associated with the non-potable reuse of onsite-collected waters; the present work reviewed the relevant QMRA literature to prioritize knowledge gaps and identify health-protective pathogen treatment reduction targets. The review indicated that ingestion of untreated, onsite-collected graywater, rainwater, seepage water and stormwater from a variety of exposure routes resulted in gastrointestinal infection risks greater than the traditional acceptable level of risk. We found no QMRAs that estimated the pathogen risks associated with onsite, non-potable reuse of blackwater. Pathogen treatment reduction targets for non-potable, onsite reuse that included a suite of reference pathogens (i.e., including relevant bacterial, protozoan, and viral hazards) were limited to graywater (for a limited set of domestic uses) and stormwater (for domestic and municipal uses). These treatment reductions corresponded with the health benchmark of a probability of infection or illness of 10−3 per person per year or less. The pathogen treatment reduction targets varied depending on the target health benchmark, reference pathogen, source water, and water reuse application. Overall, there remains a need for pathogen reduction targets that are heal

Role of the horizontal gene exchange in evolution of pathogenic Mycobacteria.

PubMed

Reva, Oleg; Korotetskiy, Ilya; Ilin, Aleksandr

2015-01-01

Mycobacterium tuberculosis is one of the most dangerous human pathogens, the causative agent of tuberculosis. While this pathogen is considered as extremely clonal and resistant to horizontal gene exchange, there are many facts supporting the hypothesis that on the early stages of evolution the development of pathogenicity of ancestral Mtb has started with a horizontal acquisition of virulence factors. Episodes of infections caused by non-tuberculosis Mycobacteria reported worldwide may suggest a potential for new pathogens to appear. If so, what is the role of horizontal gene transfer in this process? Availing of accessibility of complete genomes sequences of multiple pathogenic, conditionally pathogenic and saprophytic Mycobacteria, a genome comparative study was performed to investigate the distribution of genomic islands among bacteria and identify ontological links between these mobile elements. It was shown that the ancient genomic islands from M. tuberculosis still may be rooted to the pool of mobile genetic vectors distributed among Mycobacteria. A frequent exchange of genes was observed between M. marinum and several saprophytic and conditionally pathogenic species. Among them M. avium was the most promiscuous species acquiring genetic materials from diverse origins. Recent activation of genetic vectors circulating among Mycobacteria potentially may lead to emergence of new pathogens from environmental and conditionally pathogenic Mycobacteria. The species which require monitoring are M. marinum and M. avium as they eagerly acquire genes from different sources and may become donors of virulence gene cassettes to other micro-organisms.

Morphological characteristics and pathogenicity of fungi associated with Roselle (Hibiscus Sabdariffa) diseases in Penang, Malaysia.

PubMed

Eslaminejad, Touba; Zakaria, Maziah

2011-11-01

Roselle, or Jamaica sorrel (Hibiscus sabdariffa) is a popular vegetable in many tropical regions, cultivated for its leaves, seeds, stems and calyces which, the dried calyces are used to prepare tea, syrup, jams and jellies and as beverages. The main objectives of this study were to identify and characterise fungal pathogens associated with Roselle diseases based on their morphological and cultural characteristics and to determine the pathogenicity of four fungi infecting Roselle seedlings, namely Phoma exigua, Fusarium nygamai, Fusarium tgcq and Rhizoctonia solani in Penang. A total of 200 fungal isolates were obtained from 90 samples of symptomatic Roselle tissues. The isolates were identified based on cultural and morphological characteristics, as well as their pathogenicity. The fungal pathogen most frequently isolated was P. exigua (present in 45% of the samples), followed by F. nygamai (25%), Rhizoctonia solani (19%) and F. camptoceras (11%). Pathogenicity tests showed that P. exigua, F. nygamai, F. camptoceras and R. solani were able to infect both wounded and unwounded seedlings with different degrees of severity as indicated by the Disease severity (DS). R. solani was the most pathogenic fungus affecting both wounded and unwounded Roselle seedlings, followed by P. exigua that was highly pathogenic on wounded seedlings. F. nygamai was less pathogenic while the least pathogenic fungus was F. camptoceras, infecting only the unwounded seedlings but, surprisingly, not the wounded plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pathogen webs in collapsing honey bee colonies.

PubMed

Cornman, R Scott; Tarpy, David R; Chen, Yanping; Jeffreys, Lacey; Lopez, Dawn; Pettis, Jeffery S; vanEngelsdorp, Dennis; Evans, Jay D

2012-01-01

Recent losses in honey bee colonies are unusual in their severity, geographical distribution, and, in some cases, failure to present recognized characteristics of known disease. Domesticated honey bees face numerous pests and pathogens, tempting hypotheses that colony collapses arise from exposure to new or resurgent pathogens. Here we explore the incidence and abundance of currently known honey bee pathogens in colonies suffering from Colony Collapse Disorder (CCD), otherwise weak colonies, and strong colonies from across the United States. Although pathogen identities differed between the eastern and western United States, there was a greater incidence and abundance of pathogens in CCD colonies. Pathogen loads were highly covariant in CCD but not control hives, suggesting that CCD colonies rapidly become susceptible to a diverse set of pathogens, or that co-infections can act synergistically to produce the rapid depletion of workers that characterizes the disorder. We also tested workers from a CCD-free apiary to confirm that significant positive correlations among pathogen loads can develop at the level of individual bees and not merely as a secondary effect of CCD. This observation and other recent data highlight pathogen interactions as important components of bee disease. Finally, we used deep RNA sequencing to further characterize microbial diversity in CCD and non-CCD hives. We identified novel strains of the recently described Lake Sinai viruses (LSV) and found evidence of a shift in gut bacterial composition that may be a biomarker of CCD. The results are discussed with respect to host-parasite interactions and other environmental stressors of honey bees.

Rainfall and temperatures changes have confounding impacts on Phytophthora cinnamomi occurrence risk in the southwestern USA under climate change scenarios.

PubMed

Thompson, Sally E; Levin, Simon; Rodriguez-Iturbe, Ignacio

2014-04-01

Global change will simultaneously impact many aspects of climate, with the potential to exacerbate the risks posed by plant pathogens to agriculture and the natural environment; yet, most studies that explore climate impacts on plant pathogen ranges consider individual climatic factors separately. In this study, we adopt a stochastic modeling approach to address multiple pathways by which climate can constrain the range of the generalist plant pathogen Phytophthora cinnamomi (Pc): through changing winter soil temperatures affecting pathogen survival; spring soil temperatures and thus pathogen metabolic rates; and changing spring soil moisture conditions and thus pathogen growth rates through host root systems. We apply this model to the southwestern USA for contemporary and plausible future climate scenarios and evaluate the changes in the potential range of Pc. The results indicate that the plausible range of this pathogen in the southwestern USA extends over approximately 200,000 km(2) under contemporary conditions. While warming temperatures as projected by the IPCC A2 and B1 emissions scenarios greatly expand the range over which the pathogen can survive winter, projected reductions in spring rainfall reduce its feasible habitat, leading to spatially complex patterns of changing risk. The study demonstrates that temperature and rainfall changes associated with possible climate futures in the southwestern USA have confounding impacts on the range of Pc, suggesting that projections of future pathogen dynamics and ranges should account for multiple pathways of climate-pathogen interaction. © 2014 John Wiley & Sons Ltd.

A Standardized DNA Variant Scoring System for Pathogenicity Assessments in Mendelian Disorders

PubMed Central

Karbassi, Izabela; Maston, Glenn A.; Love, Angela; DiVincenzo, Christina; Braastad, Corey D.; Elzinga, Christopher D.; Bright, Alison R.; Previte, Domenic; Zhang, Ke; Rowland, Charles M.; McCarthy, Michele; Lapierre, Jennifer L.; Dubois, Felicita; Medeiros, Katelyn A.; Batish, Sat Dev; Jones, Jeffrey; Liaquat, Khalida; Hoffman, Carol A.; Jaremko, Malgorzata; Wang, Zhenyuan; Sun, Weimin; Buller‐Burckle, Arlene; Strom, Charles M.; Keiles, Steven B.

2015-01-01

ABSTRACT We developed a rules‐based scoring system to classify DNA variants into five categories including pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign. Over 16,500 pathogenicity assessments on 11,894 variants from 338 genes were analyzed for pathogenicity based on prediction tools, population frequency, co‐occurrence, segregation, and functional studies collected from internal and external sources. Scores were calculated by trained scientists using a quantitative framework that assigned differential weighting to these five types of data. We performed descriptive and comparative statistics on the dataset and tested interobserver concordance among the trained scientists. Private variants defined as variants found within single families (n = 5,182), were either VUS (80.5%; n = 4,169) or likely pathogenic (19.5%; n = 1,013). The remaining variants (n = 6,712) were VUS (38.4%; n = 2,577) or likely benign/benign (34.7%; n = 2,327) or likely pathogenic/pathogenic (26.9%, n = 1,808). Exact agreement between the trained scientists on the final variant score was 98.5% [95% confidence interval (CI) (98.0, 98.9)] with an interobserver consistency of 97% [95% CI (91.5, 99.4)]. Variant scores were stable and showed increasing odds of being in agreement with new data when re‐evaluated periodically. This carefully curated, standardized variant pathogenicity scoring system provides reliable pathogenicity scores for DNA variants encountered in a clinical laboratory setting. PMID:26467025

A Standardized DNA Variant Scoring System for Pathogenicity Assessments in Mendelian Disorders.

PubMed

Karbassi, Izabela; Maston, Glenn A; Love, Angela; DiVincenzo, Christina; Braastad, Corey D; Elzinga, Christopher D; Bright, Alison R; Previte, Domenic; Zhang, Ke; Rowland, Charles M; McCarthy, Michele; Lapierre, Jennifer L; Dubois, Felicita; Medeiros, Katelyn A; Batish, Sat Dev; Jones, Jeffrey; Liaquat, Khalida; Hoffman, Carol A; Jaremko, Malgorzata; Wang, Zhenyuan; Sun, Weimin; Buller-Burckle, Arlene; Strom, Charles M; Keiles, Steven B; Higgins, Joseph J

2016-01-01

We developed a rules-based scoring system to classify DNA variants into five categories including pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign. Over 16,500 pathogenicity assessments on 11,894 variants from 338 genes were analyzed for pathogenicity based on prediction tools, population frequency, co-occurrence, segregation, and functional studies collected from internal and external sources. Scores were calculated by trained scientists using a quantitative framework that assigned differential weighting to these five types of data. We performed descriptive and comparative statistics on the dataset and tested interobserver concordance among the trained scientists. Private variants defined as variants found within single families (n = 5,182), were either VUS (80.5%; n = 4,169) or likely pathogenic (19.5%; n = 1,013). The remaining variants (n = 6,712) were VUS (38.4%; n = 2,577) or likely benign/benign (34.7%; n = 2,327) or likely pathogenic/pathogenic (26.9%, n = 1,808). Exact agreement between the trained scientists on the final variant score was 98.5% [95% confidence interval (CI) (98.0, 98.9)] with an interobserver consistency of 97% [95% CI (91.5, 99.4)]. Variant scores were stable and showed increasing odds of being in agreement with new data when re-evaluated periodically. This carefully curated, standardized variant pathogenicity scoring system provides reliable pathogenicity scores for DNA variants encountered in a clinical laboratory setting. © 2015 The Authors. **Human Mutation published by Wiley Periodicals, Inc.

Transport of ixodid ticks and tick-borne pathogens by migratory birds.

PubMed

Hasle, Gunnar

2013-01-01

Birds, particularly passerines, can be parasitized by Ixodid ticks, which may be infected with tick-borne pathogens, like Borrelia spp., Babesia spp., Anaplasma, Rickettsia/Coxiella, and tick-borne encephalitis virus. The prevalence of ticks on birds varies over years, season, locality and different bird species. The prevalence of ticks on different species depends mainly on the degree of feeding on the ground. In Europe, the Turdus spp., especially the blackbird, Turdus merula, appears to be most important for harboring ticks. Birds can easily cross barriers, like fences, mountains, glaciers, desserts and oceans, which would stop mammals, and they can move much faster than the wingless hosts. Birds can potentially transport tick-borne pathogens by transporting infected ticks, by being infected with tick-borne pathogens and transmit the pathogens to the ticks, and possibly act as hosts for transfer of pathogens between ticks through co-feeding. Knowledge of the bird migration routes and of the spatial distribution of tick species and tick-borne pathogens is crucial for understanding the possible impact of birds as spreaders of ticks and tick-borne pathogens. Successful colonization of new tick species or introduction of new tick-borne pathogens will depend on suitable climate, vegetation and hosts. Although it has never been demonstrated that a new tick species, or a new tick pathogen, actually has been established in a new locality after being seeded there by birds, evidence strongly suggests that this could occur.

Transport of ixodid ticks and tick-borne pathogens by migratory birds

PubMed Central

Hasle, Gunnar

2013-01-01

Birds, particularly passerines, can be parasitized by Ixodid ticks, which may be infected with tick-borne pathogens, like Borrelia spp., Babesia spp., Anaplasma, Rickettsia/Coxiella, and tick-borne encephalitis virus. The prevalence of ticks on birds varies over years, season, locality and different bird species. The prevalence of ticks on different species depends mainly on the degree of feeding on the ground. In Europe, the Turdus spp., especially the blackbird, Turdus merula, appears to be most important for harboring ticks. Birds can easily cross barriers, like fences, mountains, glaciers, desserts and oceans, which would stop mammals, and they can move much faster than the wingless hosts. Birds can potentially transport tick-borne pathogens by transporting infected ticks, by being infected with tick-borne pathogens and transmit the pathogens to the ticks, and possibly act as hosts for transfer of pathogens between ticks through co-feeding. Knowledge of the bird migration routes and of the spatial distribution of tick species and tick-borne pathogens is crucial for understanding the possible impact of birds as spreaders of ticks and tick-borne pathogens. Successful colonization of new tick species or introduction of new tick-borne pathogens will depend on suitable climate, vegetation and hosts. Although it has never been demonstrated that a new tick species, or a new tick pathogen, actually has been established in a new locality after being seeded there by birds, evidence strongly suggests that this could occur. PMID:24058903

Cell-cell recognition of host surfaces by pathogens. The adsorption of maize (Zea mays) root mucilage by surfaces of pathogenic fungi.

PubMed Central

Gould, J; Northcote, D H

1986-01-01

The adsorption of radioactive mucilage by pathogenic fungi was shown to be dependent upon time, the composition of mucilage, the type of fungal surface (conidia, hyphae, hyphal apices), fungal species, pH and bivalent cations. All fungal adhesins were inactivated by either proteinase or polysaccharase treatments. Adsorption was not inhibited by the numberous mono-, di- and oligo-saccharides that were tested individually, but it was inhibited absolutely by several polysaccharides. This suggested that adsorption of mucilage by pathogens involved conformational and ionic interactions between plant and fungal polymers but not fungal lectins bound to sugar residues of mucilage. Several fractionation schemes showed that pathogens bound only the most acidic of the variety of polymers that comprise mucilage. There was not any absolute distinction between ability to bind radioactive mucilage and type of pathogen or non-pathogen. However, there were notable differences in characteristics of adsorption between two types of pathogen. Differences were revealed by comparison of the adsorption capacities of conidia and germinant conidia and chromatography of radioactive mucilage on germinant conidia. An ectotrophic root-infecting fungus (a highly specialized pathogen) bound a greater proportion of mucilage than did a vascular-wilt fungus (of catholic host and tissue range) with more than one class of site for adsorption. In contrast with the vascular-wilt fungus, sites for adsorption on the specialized pathogen were present solely on surfaces formed by germination. PMID:3954742

Alzheimer's Disease: APP, Gamma Secretase, APOE, CLU, CR1, PICALM, ABCA7, BIN1, CD2AP, CD33, EPHA1, and MS4A2, and Their Relationships with Herpes Simplex, C. Pneumoniae, Other Suspect Pathogens, and the Immune System

PubMed Central

Carter, Chris

2011-01-01

Alzheimer's disease susceptibility genes, APP and gamma-secretase, are involved in the herpes simplex life cycle, and that of other suspect pathogens (C. pneumoniae, H. pylori, C. neoformans, B. burgdorferri, P. gingivalis) or immune defence. Such pathogens promote beta-amyloid deposition and tau phosphorylation and may thus be causative agents, whose effects are conditioned by genes. The antimicrobial effects of beta-amyloid, the localisation of APP/gamma-secretase in immunocompetent dendritic cells, and gamma secretase cleavage of numerous pathogen receptors suggest that this network is concerned with pathogen disposal, effects which may be abrogated by the presence of beta-amyloid autoantibodies in the elderly. These autoantibodies, as well as those to nerve growth factor and tau, also observed in Alzheimer's disease, may well be antibodies to pathogens, due to homology between human autoantigens and pathogen proteins. NGF or tau antibodies promote beta-amyloid deposition, neurofibrillary tangles, or cholinergic neuronal loss, and, with other autoantibodies, such as anti-ATPase, are potential agents of destruction, whose formation is dictated by sequence homology between pathogen and human proteins, and thus by pathogen strain and human genes. Pathogen elimination in the ageing population and removal of culpable autoantibodies might reduce the incidence and offer hope for a cure in this affliction. PMID:22254144

Risks Posed by Reston, the Forgotten Ebolavirus

PubMed Central

Cantoni, Diego; Hamlet, Arran; Michaelis, Martin; Wass, Mark N.

2016-01-01

ABSTRACT Out of the five members of the Ebolavirus family, four cause life-threatening disease, whereas the fifth, Reston virus (RESTV), is nonpathogenic in humans. The reasons for this discrepancy remain unclear. In this review, we analyze the currently available information to provide a state-of-the-art summary of the factors that determine the human pathogenicity of Ebolaviruses. RESTV causes sporadic infections in cynomolgus monkeys and is found in domestic pigs throughout the Philippines and China. Phylogenetic analyses revealed that RESTV is most closely related to the Sudan virus, which causes a high mortality rate in humans. Amino acid sequence differences between RESTV and the other Ebolaviruses are found in all nine Ebolavirus proteins, though no one residue appears sufficient to confer pathogenicity. Changes in the glycoprotein contribute to differences in Ebolavirus pathogenicity but are not sufficient to confer pathogenicity on their own. Similarly, differences in VP24 and VP35 affect viral immune evasion and are associated with changes in human pathogenicity. A recent in silico analysis systematically determined the functional consequences of sequence variations between RESTV and human-pathogenic Ebolaviruses. Multiple positions in VP24 were differently conserved between RESTV and the other Ebolaviruses and may alter human pathogenicity. In conclusion, the factors that determine the pathogenicity of Ebolaviruses in humans remain insufficiently understood. An improved understanding of these pathogenicity-determining factors is of crucial importance for disease prevention and for the early detection of emergent and potentially human-pathogenic RESTVs. PMID:28066813

Impacts of Climate Change on Indirect Human Exposure to Pathogens and Chemicals from Agriculture

PubMed Central

Boxall, Alistair B.A.; Hardy, Anthony; Beulke, Sabine; Boucard, Tatiana; Burgin, Laura; Falloon, Peter D.; Haygarth, Philip M.; Hutchinson, Thomas; Kovats, R. Sari; Leonardi, Giovanni; Levy, Leonard S.; Nichols, Gordon; Parsons, Simon A.; Potts, Laura; Stone, David; Topp, Edward; Turley, David B.; Walsh, Kerry; Wellington, Elizabeth M.H.; Williams, Richard J.

2009-01-01

Objective Climate change is likely to affect the nature of pathogens and chemicals in the environment and their fate and transport. Future risks of pathogens and chemicals could therefore be very different from those of today. In this review, we assess the implications of climate change for changes in human exposures to pathogens and chemicals in agricultural systems in the United Kingdom and discuss the subsequent effects on health impacts. Data sources In this review, we used expert input and considered literature on climate change; health effects resulting from exposure to pathogens and chemicals arising from agriculture; inputs of chemicals and pathogens to agricultural systems; and human exposure pathways for pathogens and chemicals in agricultural systems. Data synthesis We established the current evidence base for health effects of chemicals and pathogens in the agricultural environment; determined the potential implications of climate change on chemical and pathogen inputs in agricultural systems; and explored the effects of climate change on environmental transport and fate of different contaminant types. We combined these data to assess the implications of climate change in terms of indirect human exposure to pathogens and chemicals in agricultural systems. We then developed recommendations on future research and policy changes to manage any adverse increases in risks. Conclusions Overall, climate change is likely to increase human exposures to agricultural contaminants. The magnitude of the increases will be highly dependent on the contaminant type. Risks from many pathogens and particulate and particle-associated contaminants could increase significantly. These increases in exposure can, however, be managed for the most part through targeted research and policy changes. PMID:19440487

Inducible defense against pathogens and parasites: optimal choice among multiple options.

PubMed

Shudo, E; Iwasa, Y

2001-03-21

Defense against pathogen, parasites and herbivores is often enhanced after their invasion into the host's body. Sometimes different options are adopted depending on the identity and the quantity of the pathogen, exemplified by the switch between Th1 and Th2 systems in mammalian immunity. In this paper, we study the optimal defense of the host when two alternative responses are available, which differ in the effectiveness of suppressing the growth of pathogen (parasite, or herbivore), the damage to the host caused by the defense response, and the magnitude of time delay before the defense response becomes fully effective. The optimal defense is the one that minimizes the sum of the damages caused by the pathogen and the cost due to defense activities. The damage by pathogens increases in proportion to the time integral of the pathogen abundance, and the cost is proportional to the defense activity. We can prove that a single globally optimal combination of defense options always exists and there is no other local optimum. Depending on the parameters, the optimal is to adopt only the early response, only the late response, or both responses. The defense response with a shorter time delay is more heavily used when the pathogen grows fast, the initial pathogen abundance is large, and the difference in time delay is long. We also study the host's optimal choice between constitutive and inducible defenses. In the constitutive defense, the response to pathogen attack works without delay, but it causes the cost even when the pathogen attack does not occur. We discuss mammalian immunity and the plant chemical defense from the model's viewpoint. Copyright 2001 Academic Press.

A Rapid Spin Column-Based Method to Enrich Pathogen Transcripts from Eukaryotic Host Cells Prior to Sequencing

DOE PAGES

Bent, Zachary W.; Poorey, Kunal; LaBauve, Annette E.; ...

2016-12-21

When analyzing pathogen transcriptomes during the infection of host cells, the signal-to-background (pathogen-to-host) ratio of nucleic acids (NA) in infected samples is very small. Despite the advancements in next-generation sequencing, the minute amount of pathogen NA makes standard RNA-seq library preps inadequate for effective gene-level analysis of the pathogen in cases with low bacterial loads. In order to provide a more complete picture of the pathogen transcriptome during an infection, we developed a novel pathogen enrichment technique, which can enrich for transcripts from any cultivable bacteria or virus, using common, readily available laboratory equipment and reagents. To evenly enrich formore » pathogen transcripts, we generate biotinylated pathogen-targeted capture probes in an enzymatic process using the entire genome of the pathogen as a template. The capture probes are hybridized to a strand-specific cDNA library generated from an RNA sample. The biotinylated probes are captured on a monomeric avidin resin in a miniature spin column, and enriched pathogen-specific cDNA is eluted following a series of washes. To test this method, we performed an in vitro time-course infection using Klebsiella pneumoniae to infect murine macrophage cells. K. pneumoniae transcript enrichment efficiency was evaluated using RNA-seq. Bacterial transcripts were enriched up to ~400-fold, and allowed the recovery of transcripts from ~2000–3600 genes not observed in untreated control samples. These additional transcripts revealed interesting aspects of K. pneumoniae biology including the expression of putative virulence factors and the expression of several genes responsible for antibiotic resistance even in the absence of drugs.« less

Pathogenic flora composition and overview of the trends used for bacterial pathogenicity identifications.

PubMed

Orji, Frank Anayo; Ugbogu, Ositadinma Chinyere; Ugbogu, Eziuche Amadike; Barbabosa-Pliego, Alberto; Monroy, Jose Cedillo; Elghandour, Mona M M Y; Salem, Abdelfattah Z M

2018-05-05

Over 250 species of resident flora in the class of bacteria are known to be associated with humans. These conventional flora compositions is often determined by factors which may not be limited to genetics, age, sex, stress and nutrition of humans. Man is constantly in contact with bacteria through media such as air, water, soil and food. This paper reviews the concept of bacterial pathogenesis from the sequential point of colonization to tissue injury. The paper in addition to examination of the factors which enhance virulence in bacterial pathogens also x-rayed the concept of pathogenicity islands and the next generation approaches or rather current trends/methods used in the bacterial pathogenicity investigations. In terms of pathogenicity which of course is the capacity to cause disease in animals, requires that the attacking bacterial strain is virulent, and has ability to bypass the host immune defensive mechanisms. In order to achieve or exhibit pathogenicity, the virulence factors required by microorganisms include capsule, pigments, enzymes, iron acquisition through siderophores. Bacterial Pathogenicity Islands as a distinct concept in bacterial pathogenesis are just loci on the chromosome or extra chromosomal units which are acquired by horizontal gene transfer within pathogens in a microbial community or biofilm. In the area of laboratory investigations, bacterial pathogenesis was initially carried out using culture dependent approaches, which can only detect about 1% of human and veterinary-important pathogens. However, in the recent paradigms shift, the use of proteomics, metagenomics, phylogenetic tree analyses, spooligotyping, and finger printing etc. have made it possible that 100% of the bacterial pathogens in nature can be extensively studied. Copyright © 2018 Elsevier Ltd. All rights reserved.

Within-host competitive exclusion among species of the anther smut pathogen

PubMed Central

Gold, Alexander; Giraud, Tatiana; Hood, Michael E

2009-01-01

Background Host individuals represent an arena in which pathogens compete for resources and transmission opportunities, with major implications for the evolution of virulence and the structure of populations. Studies to date have focused on competitive interactions within pathogen species, and the level of antagonism tends to increase with the genetic distance between competitors. Anther-smut fungi, in the genus Microbotryum, have emerged as a tractable model for within-host competition. Here, using two pathogen species that are frequently found in sympatry, we investigated whether the antagonism seen among genotypes of the same species cascades up to influence competition among pathogen species. Results Sequential inoculation of hosts showed that a resident infection most often excludes a challenging pathogen genotype, which is consistent with prior studies. However, the challenging pathogen was significantly more likely to invade the already-infected host if the resident infection was a conspecific genotype compared to challenges involving a closely related species. Moreover, when inter-specific co-infection occurred, the pathogens were highly segregated within the host, in contrast to intra-specific co-infection. Conclusion We show evidence that competitive exclusion during infection can be greater among closely related pathogen species than among genotypes within species. This pattern follows from prior studies demonstrating that genetic distance and antagonistic interactions are positively correlated in Microbotryum. Fungal vegetative incompatibility is a likely mechanism of direct competitive interference, and has been shown in some fungi to be effective both within and across species boundaries. For systems where related pathogen species frequently co-occur in the same host populations, these competitive dynamics may substantially impact the spatial segregation of pathogen species. PMID:19422703

National Institute of Allergy and Infectious Disease (NIAID) Funding for Studies of Hospital-Associated Bacterial Pathogens: Are Funds Proportionate to Burden of Disease?

PubMed

Kwon, Seunghyug; Schweizer, Marin L; Perencevich, Eli N

2012-01-26

Hospital-associated infections (HAIs) are associated with a considerable burden of disease and direct costs greater than $17 billion. The pathogens that cause the majority of serious HAIs are Enterococcus faecium, Staphylococcus aureus, Clostridium difficile, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species, referred as ESCKAPE. We aimed to determine the amount of funding the National Institute of Health (NIH) National Institute of Allergy and Infectious Diseases (NIAID) allocates to research on antimicrobial resistant pathogens, particularly ESCKAPE pathogens. The NIH Research Portfolio Online Reporting Tools (RePORT) database was used to identify NIAID antimicrobial resistance research grants funded in 2007-2009 using the terms "antibiotic resistance," "antimicrobial resistance," and "hospital-associated infection." Funding for antimicrobial resistance grants has increased from 2007-2009. Antimicrobial resistance funding for bacterial pathogens has seen a smaller increase than non-bacterial pathogens. The total funding for all ESKCAPE pathogens was $ 22,005,943 in 2007, $ 30,810,153 in 2008 and $ 49,801,227 in 2009. S. aureus grants received $ 29,193,264 in FY2009, the highest funding amount of all the ESCKAPE pathogens. Based on 2009 funding data, approximately $1,565 of research money was spent per S. aureus related death and $750 of was spent per C. difficile related death. Although the funding for ESCKAPE pathogens has increased from 2007 to 2009, funding levels for antimicrobial resistant bacteria-related grants is still lower than funding for antimicrobial resistant non-bacterial pathogens. Efforts may be needed to improve research funding for resistant-bacterial pathogens, particularly as their clinical burden increases.

Receiver-operating characteristic curves for somatic cell scores and California mastitis test in Valle del Belice dairy sheep.

PubMed

Riggio, Valentina; Pesce, Lorenzo L; Morreale, Salvatore; Portolano, Baldassare

2013-06-01

Using receiver-operating characteristic (ROC) curve methodology this study was designed to assess the diagnostic effectiveness of somatic cell count (SCC) and the California mastitis test (CMT) in Valle del Belice sheep, and to propose and evaluate threshold values for those tests that would optimally discriminate between healthy and infected udders. Milk samples (n=1357) were collected from 684 sheep in four flocks. The prevalence of infection, as determined by positive bacterial culture was 0.36, 87.7% of which were minor and 12.3% major pathogens. Of the culture negative samples, 83.7% had an SCC<500,000/mL and 97.4% had <1,000,000cells/mL. When the associations between SC score (SCS) and whole sample status (culture negative vs. infected), minor pathogen status (culture negative vs. infected with minor pathogens), major pathogen status (culture negative vs. infected with major pathogens), and CMT results were evaluated, the estimated area under the ROC curve was greater for glands infected with major compared to minor pathogens (0.88 vs. 0.73), whereas the area under the curve considering all pathogens was similar to the one for minor pathogens (0.75). The estimated optimal thresholds were 3.00 (CMT), 2.81 (SCS for the whole sample), 2.81 (SCS for minor pathogens), and 3.33 (SCS for major pathogens). These correctly classified, respectively, 69.0%, 73.5%, 72.6% and 91.0% of infected udders in the samples. The CMT appeared only to discriminate udders infected with major pathogens. In this population, SCS appeared to be the best indirect test of the bacteriological status of the udder. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Rapid Spin Column-Based Method to Enrich Pathogen Transcripts from Eukaryotic Host Cells Prior to Sequencing

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

Bent, Zachary W.; Poorey, Kunal; LaBauve, Annette E.

When analyzing pathogen transcriptomes during the infection of host cells, the signal-to-background (pathogen-to-host) ratio of nucleic acids (NA) in infected samples is very small. Despite the advancements in next-generation sequencing, the minute amount of pathogen NA makes standard RNA-seq library preps inadequate for effective gene-level analysis of the pathogen in cases with low bacterial loads. In order to provide a more complete picture of the pathogen transcriptome during an infection, we developed a novel pathogen enrichment technique, which can enrich for transcripts from any cultivable bacteria or virus, using common, readily available laboratory equipment and reagents. To evenly enrich formore » pathogen transcripts, we generate biotinylated pathogen-targeted capture probes in an enzymatic process using the entire genome of the pathogen as a template. The capture probes are hybridized to a strand-specific cDNA library generated from an RNA sample. The biotinylated probes are captured on a monomeric avidin resin in a miniature spin column, and enriched pathogen-specific cDNA is eluted following a series of washes. To test this method, we performed an in vitro time-course infection using Klebsiella pneumoniae to infect murine macrophage cells. K. pneumoniae transcript enrichment efficiency was evaluated using RNA-seq. Bacterial transcripts were enriched up to ~400-fold, and allowed the recovery of transcripts from ~2000–3600 genes not observed in untreated control samples. These additional transcripts revealed interesting aspects of K. pneumoniae biology including the expression of putative virulence factors and the expression of several genes responsible for antibiotic resistance even in the absence of drugs.« less

Communicable Diseases Prioritized for Surveillance and Epidemiological Research: Results of a Standardized Prioritization Procedure in Germany, 2011

PubMed Central

Balabanova, Yanina; Gilsdorf, Andreas; Buda, Silke; Burger, Reinhard; Eckmanns, Tim; Gärtner, Barbara; Groß, Uwe; Haas, Walter; Hamouda, Osamah; Hübner, Johannes; Jänisch, Thomas; Kist, Manfred; Kramer, Michael H.; Ledig, Thomas; Mielke, Martin; Pulz, Matthias; Stark, Klaus; Suttorp, Norbert; Ulbrich, Uta; Wichmann, Ole; Krause, Gérard

2011-01-01

Introduction To establish strategic priorities for the German national public health institute (RKI) and guide the institute's mid-term strategic decisions, we prioritized infectious pathogens in accordance with their importance for national surveillance and epidemiological research. Methods We used the Delphi process with internal (RKI) and external experts and a metric-consensus approach to score pathogens according to ten three-tiered criteria. Additional experts were invited to weight each criterion, leading to the calculation of a median weight by which each score was multiplied. We ranked the pathogens according to the total weighted score and divided them into four priority groups. Results 127 pathogens were scored. Eighty-six experts participated in the weighting; “Case fatality rate” was rated as the most important criterion. Twenty-six pathogens were ranked in the highest priority group; among those were pathogens with internationally recognised importance (e.g., Human Immunodeficiency Virus, Mycobacterium tuberculosis, Influenza virus, Hepatitis C virus, Neisseria meningitides), pathogens frequently causing large outbreaks (e.g., Campylobacter spp.), and nosocomial pathogens associated with antimicrobial resistance. Other pathogens in the highest priority group included Helicobacter pylori, Respiratory Syncytial Virus, Varicella zoster virus and Hantavirus. Discussion While several pathogens from the highest priority group already have a high profile in national and international health policy documents, high scores for other pathogens (e.g., Helicobacter pylori, Respiratory syncytial virus or Hantavirus) indicate a possible under-recognised importance within the current German public health framework. A process to strengthen respective surveillance systems and research has been started. The prioritization methodology has worked well; its modular structure makes it potentially useful for other settings. PMID:21991334

Bioinformatics comparisons of RNA-binding proteins of pathogenic and non-pathogenic Escherichia coli strains reveal novel virulence factors.

PubMed

Ghosh, Pritha; Sowdhamini, Ramanathan

2017-08-24

Pathogenic bacteria have evolved various strategies to counteract host defences. They are also exposed to environments that are undergoing constant changes. Hence, in order to survive, bacteria must adapt themselves to the changing environmental conditions by performing regulations at the transcriptional and/or post-transcriptional levels. Roles of RNA-binding proteins (RBPs) as virulence factors have been very well studied. Here, we have used a sequence search-based method to compare and contrast the proteomes of 16 pathogenic and three non-pathogenic E. coli strains as well as to obtain a global picture of the RBP landscape (RBPome) in E. coli. Our results show that there are no significant differences in the percentage of RBPs encoded by the pathogenic and the non-pathogenic E. coli strains. The differences in the types of Pfam domains as well as Pfam RNA-binding domains, encoded by these two classes of E. coli strains, are also insignificant. The complete and distinct RBPome of E. coli has been established by studying all known E. coli strains till date. We have also identified RBPs that are exclusive to pathogenic strains, and most of them can be exploited as drug targets since they appear to be non-homologous to their human host proteins. Many of these pathogen-specific proteins were uncharacterised and their identities could be resolved on the basis of sequence homology searches with known proteins. Detailed structural modelling, molecular dynamics simulations and sequence comparisons have been pursued for selected examples to understand differences in stability and RNA-binding. The approach used in this paper to cross-compare proteomes of pathogenic and non-pathogenic strains may also be extended to other bacterial or even eukaryotic proteomes to understand interesting differences in their RBPomes. The pathogen-specific RBPs reported in this study, may also be taken up further for clinical trials and/or experimental validations.

Modeling the intracellular pathogen-immune interaction with cure rate

NASA Astrophysics Data System (ADS)

Dubey, Balram; Dubey, Preeti; Dubey, Uma S.

2016-09-01

Many common and emergent infectious diseases like Influenza, SARS, Hepatitis, Ebola etc. are caused by viral pathogens. These infections can be controlled or prevented by understanding the dynamics of pathogen-immune interaction in vivo. In this paper, interaction of pathogens with uninfected and infected cells in presence or absence of immune response are considered in four different cases. In the first case, the model considers the saturated nonlinear infection rate and linear cure rate without absorption of pathogens into uninfected cells and without immune response. The next model considers the effect of absorption of pathogens into uninfected cells while all other terms are same as in the first case. The third model incorporates innate immune response, humoral immune response and Cytotoxic T lymphocytes (CTL) mediated immune response with cure rate and without absorption of pathogens into uninfected cells. The last model is an extension of the third model in which the effect of absorption of pathogens into uninfected cells has been considered. Positivity and boundedness of solutions are established to ensure the well-posedness of the problem. It has been found that all the four models have two equilibria, namely, pathogen-free equilibrium point and pathogen-present equilibrium point. In each case, stability analysis of each equilibrium point is investigated. Pathogen-free equilibrium is globally asymptotically stable when basic reproduction number is less or equal to unity. This implies that control or prevention of infection is independent of initial concentration of uninfected cells, infected cells, pathogens and immune responses in the body. The proposed models show that introduction of immune response and cure rate strongly affects the stability behavior of the system. Further, on computing basic reproduction number, it has been found to be minimum for the fourth model vis-a-vis other models. The analytical findings of each model have been exemplified by numerical simulations.

Processes affecting the transport of Cryptosporidium parvum and other persistent pathogens in surface- and ground-waters

NASA Astrophysics Data System (ADS)

Packman, A. I.; Lau, B. L.; Harter, T.; Atwill, E. R.

2007-12-01

Waterborne diseases are transmitted through numerous environmental pathways, and their migration is strongly mediated by interaction with a wide variety of sediments and other natural materials during transport. Here we provide an overview of factors that affect the fate of persistent water-borne pathogens, focusing particularly on the zoonotic pathogen Cryptosporidium parvum as an example. While individual microbial cells are both small and have low specific gravity, suggesting that they should be highly mobile and remain suspended for long periods of time, attachment to a variety of background materials can substantially reduce pathogen mobility. Cryptosporidium oocysts readily associate with both inorganic and organic particles, resulting in the formation of aggregates. This process tends to increase the effective settling velocity of C. parvum in surface waters. Similarly, pathogens readily become associated with the solid matrix during transport in groundwater, resulting in removal by filtration. However, this process is reversible with C. parvum, resulting in a slow long-term release following the initial deposition. Pathogens also become associated with biofilms, which are surface-attached communities of microorganisms in a gelatinous matrix. The presence of biofilms increases the immobilization and retention of Cryptosporidium on solid surfaces. All of these processes influence pathogen transmission in surface waters such as rivers and water-supply canals. In these environments, pathogens can be immobilized by deposition into stable sediment beds by a combination of gravitational sedimentation and advection into pore waters followed by subsurface filtration. Association with background suspended matter tends to increase pathogen deposition by sedimentation, and the presence of benthic (sedimentary) biofilms also tends to increase pathogen retention. For pathogens that remain viable for long periods of time in natural aquatic systems, as is the case with Cryptosporidium and other cyst-and spore-forming organisms, then the sediments and sedimentary biofilms become an environmental reservoir of pathogens. Cysts retained in biofilms appear to be relatively difficult to resuspend, but slow, long-term biological release and high-flow events that mobilize streambed sediments both deliver pathogens into transport.

Microbes and masculinity: Does exposure to pathogenic cues alter women's preferences for male facial masculinity and beardedness?

PubMed

McIntosh, Toneya L; Lee, Anthony J; Sidari, Morgan J; Stower, Rebecca E; Sherlock, James M; Dixson, Barnaby J W

2017-01-01

Women's preferences for men's androgen dependent secondary sexual traits are proposed to be phenotypically plastic in response to exposure to pathogens and pathogen disgust. While previous studies report that masculinity in facial shape is more attractive to women who have recently been exposed to pathogenic cues and who are high in self-reported pathogen disgust, facial hair may reduce male attractiveness under conditions of high pathogens as beards are a possible breeding ground for disease carrying ectoparasites. In the present study, we test whether women's preferences for beardedness and facial masculinity vary due to exposure to different pathogenic cues. Participants (N = 688, mean age + 1SD = 31.94 years, SD = 6.69, range = 18-67) rated the attractiveness of facial composite stimuli of men when they were clean-shaven or fully bearded. These stimuli were also manipulated in order to vary sexual dimorphism by ±50%. Ratings were conducted before and after exposure to one of four experimental treatments in which participants were primed to either high pathogens (e.g. infected cuts), ectoparasites (e.g. body lice), a mixture of pathogens and ectoparasites, or a control condition (e.g. innocuous liquids). Participants then completed the three-domain disgust scale measuring attitudes to moral, sexual and pathogen disgust. We predicted that women would prefer facial masculinity following exposure to pathogenic cues, but would show reduced preferences for facial hair following exposure to ectoparasites. Women preferred full beards over clean-shaven faces and masculinised over feminised faces. However, none of the experimental treatments influenced the direction of preferences for facial masculinity or beardedness. We also found no association between women's self-reported pathogen disgust and their preferences for facial masculinity. However, there was a weak positive association between moral disgust scores and preferences for facial masculinity, which might reflect conservatism and preferences for gender typicality in faces. Women's preferences for beards were positively associated with their pathogen disgust, which runs contrary to our predictions and may reflect preferences for high quality individuals who can withstand any costs of beardedness, although further replications are necessary before firm conclusions can be made. We conclude that there is little support for pathogenic exposure being a mechanism that underpins women's directional preferences for masculine traits.

Microbes and masculinity: Does exposure to pathogenic cues alter women’s preferences for male facial masculinity and beardedness?

PubMed Central

McIntosh, Toneya L.; Lee, Anthony J.; Sidari, Morgan J.; Stower, Rebecca E.; Sherlock, James M.

2017-01-01

Women’s preferences for men’s androgen dependent secondary sexual traits are proposed to be phenotypically plastic in response to exposure to pathogens and pathogen disgust. While previous studies report that masculinity in facial shape is more attractive to women who have recently been exposed to pathogenic cues and who are high in self-reported pathogen disgust, facial hair may reduce male attractiveness under conditions of high pathogens as beards are a possible breeding ground for disease carrying ectoparasites. In the present study, we test whether women’s preferences for beardedness and facial masculinity vary due to exposure to different pathogenic cues. Participants (N = 688, mean age + 1SD = 31.94 years, SD = 6.69, range = 18–67) rated the attractiveness of facial composite stimuli of men when they were clean-shaven or fully bearded. These stimuli were also manipulated in order to vary sexual dimorphism by ±50%. Ratings were conducted before and after exposure to one of four experimental treatments in which participants were primed to either high pathogens (e.g. infected cuts), ectoparasites (e.g. body lice), a mixture of pathogens and ectoparasites, or a control condition (e.g. innocuous liquids). Participants then completed the three-domain disgust scale measuring attitudes to moral, sexual and pathogen disgust. We predicted that women would prefer facial masculinity following exposure to pathogenic cues, but would show reduced preferences for facial hair following exposure to ectoparasites. Women preferred full beards over clean-shaven faces and masculinised over feminised faces. However, none of the experimental treatments influenced the direction of preferences for facial masculinity or beardedness. We also found no association between women’s self-reported pathogen disgust and their preferences for facial masculinity. However, there was a weak positive association between moral disgust scores and preferences for facial masculinity, which might reflect conservatism and preferences for gender typicality in faces. Women’s preferences for beards were positively associated with their pathogen disgust, which runs contrary to our predictions and may reflect preferences for high quality individuals who can withstand any costs of beardedness, although further replications are necessary before firm conclusions can be made. We conclude that there is little support for pathogenic exposure being a mechanism that underpins women’s directional preferences for masculine traits. PMID:28594843

Environmental Transport of Emerging Human-Pathogenic Cryptosporidium Species and Subtypes through Combined Sewer Overflow and Wastewater

PubMed Central

Huang, Chengchen; Hu, Yue; Wang, Lin; Wang, Yuanfei; Li, Na; Guo, Yaqiong; Xiao, Lihua

2017-01-01

ABSTRACT The environmental transport of Cryptosporidium spp. through combined sewer overflow (CSO) and the occurrence of several emerging human-pathogenic Cryptosporidium species in developing countries remain unclear. In this study, we collected 40 CSO samples and 40 raw wastewater samples from Shanghai, China, and examined them by PCR and DNA sequencing for Cryptosporidium species (targeting the small subunit rRNA gene) and Giardia duodenalis (targeting the triosephosphate isomerase, β-giardin, and glutamate dehydrogenase genes) and Enterocytozoon bieneusi (targeting the ribosomal internal transcribed spacer) genotypes. Human-pathogenic Cryptosporidium species were further subtyped by sequence analysis of the 60-kDa glycoprotein gene, with additional multilocus sequence typing on the emerging zoonotic pathogen Cryptosporidium ubiquitum. Cryptosporidium spp., G. duodenalis, and E. bieneusi were detected in 12 and 15, 33 and 32, and 37 and 40 CSO and wastewater samples, respectively, including 10 Cryptosporidium species, 3 G. duodenalis assemblages, and 8 E. bieneusi genotypes. In addition to Cryptosporidium hominis and Cryptosporidium parvum, two new pathogens identified in industrialized nations, C. ubiquitum and Cryptosporidium viatorum, were frequently detected. The two novel C. ubiquitum subtype families identified appeared to be genetic recombinants of known subtype families. Similarly, the dominant group 1 E. bieneusi genotypes and G. duodenalis subassemblage AII are known human pathogens. The similar distribution of human-pathogenic Cryptosporidium species and E. bieneusi and G. duodenalis genotypes between wastewater and CSO samples reaffirms that storm overflow is potentially a significant contamination source of pathogens in surface water. The frequent identification of C. ubiquitum and C. viatorum in urban wastewater suggests that these newly identified human pathogens may be endemic in China. IMPORTANCE Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi are major waterborne pathogens. Their transport into surface water through combined sewer overflow, which remains largely untreated in developing countries, has not been examined. In addition, the identification of these pathogens to genotypes and subtypes in urban storm overflow and wastewater is necessary for rapid and accurate assessment of pathogen transmission in humans and transport in the environment. Data from this study suggest that, like untreated urban wastewater, combined sewer overflow is commonly contaminated with human-pathogenic Cryptosporidium, G. duodenalis, and E. bieneusi genotypes and subtypes, and urban storm overflow potentially plays a significant role in the contamination of drinking source water and recreational water with human pathogens. They also indicate that Cryptosporidium ubiquitum and Cryptosporidium viatorum, two newly identified human pathogens, may be common in China, and genetic recombination can lead to the emergence of novel C. ubiquitum subtype families. PMID:28600310

Drought Impact on the Soilborne Fungal Pathogen of Tomato: Fusarium Oxysporum f. sp. Lycopersici Race 3

NASA Astrophysics Data System (ADS)

Raju, T.

2016-12-01

This paper reviews the drought impact on fungal pathogen of tomato. It presents the 11 Main Procedures used to conduct the experiments and discusses materials used. The 11 procedures are: Gather All the Soils, Sterilize the Soils Using Auto-Clave, Water Retention Test Using Auto-Clave, Cultivate Pathogen, Grow Tomato Plant, Count Pathogenic Cells, Inoculate the Pathogen, Conduct Root Dip, Grow Positive and Negative Samples, Test for Fusarium, and the Soil Separation Experiment with Pathogenic Soil. Experiments conducted on 6 Main Soils used in farming throughout California. The Yolo Series, Whiterock Series, Euic Soil, Potting Soil, Blacklock Series, and Henneke Series. The 6 Soils include amounts of clay, silt, sand, loam, and humus. It was crucial that these soils include these properties because deriving from last year's research I found that these particles in the soil has a role in the growth of the plant. Next, I tested the dry/wet weight of the soils, as this gave me a good estimate of how much water the soils can retain. This is very important because I found a direct correlation between the soil that retained the most amount of water and the soil that had the least harms done. Next, the other labs were completed to cultivate, inoculate, and test the pathogens in the soil, now these steps must be carried out with accuracy and precision because pathogens are a biological agent that causes disease or illness to its host, and if even 0.100 mL is changed in the pathogenic level it can make a large difference. Later, after I finished conducting the root dip, and raising the tomato plants. I counted the Fusarium count in the soil and plated the samples, where I was able to find the results on how much harm the pathogen had on the plant. In each of the 90 reps. the Fusarium (soilborne pathogen) decreased a little, which factors in the transfer from Potato Dextrose Agar Petri Dish to the Soils. After, this transfer the pathogen decreased and never increased, but from my Pathogen Severity Experiment, the harms done to the Early Pak 7 Tomato Plants were much greater, in soils with lower amounts of pathogen. This is because the pathogen was dying in soils with low water content, and dry material. Since, the soil was poor the plant's vascular system was weak, thus it was easier for a small Colony Forming Unit to weaken the plant and eventually kill it.

Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis at calving in dairy herds with suboptimal udder health.

PubMed

Lundberg, Å; Nyman, A-K; Aspán, A; Börjesson, S; Unnerstad, H Ericsson; Waller, K Persson

2016-03-01

Udder infections with Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis are common causes of bovine mastitis. To study these pathogens in early lactation, a 12-mo longitudinal, observational study was carried out in 13 herds with suboptimal udder health. The aims of the study were to investigate the occurrence of these pathogens and to identify if presence of the 3 pathogens, and of genotypes within the pathogens, differed with respect to herd, season, and parity. Quarter milk samples, collected at calving and 4 d in milk (DIM), were cultured for the 3 pathogens. Genotyping of staphylococcal and streptococcal isolates was performed using spa typing and pulsed-field gel electrophoresis, respectively. For each of the 3 pathogens, cows with an udder infection at calving or 4 DIM were allocated to 1 of 4 infection types: cleared (pathogen present only at calving), persistent (pathogen present in the same quarter at calving and 4 DIM), new (pathogen present only at 4 DIM), or cleared/new (pathogen present in 1 quarter at calving and in another quarter at 4 DIM). Associations between season or parity and overall occurrence of pathogens or infection types were determined using univariable mixed-effect logistic-regression models and the Fisher's exact test, respectively. The most commonly occurring pathogen was Staph. aureus, followed by Strep. dysgalactiae and Strep. uberis. Persistent infections were the most common infection type among Staph. aureus-infected cows, whereas cleared infections were the most common among Strep. dysgalactiae- and Strep. uberis-positive cows. The proportion of cows with persistent Staph. aureus infections and the proportion of cows having a Strep. uberis infection at calving or 4 DIM were higher in the multiparous cows than in primiparous cows. Infections with Strep. dysgalactiae were less common during the early housing season than during the late housing or pasture seasons, whereas persistent Strep. uberis infections were less common during the pasture season than during the late housing season. The relative occurrence of the 3 pathogens, infection types of each pathogen, and genotype diversity of each pathogen throughout the year or in different seasons and parities varied among the herds, indicating that underlying factors predisposing for udder infections at calving differ between herds. Genotyping of bacterial isolates gave important insight into how such infection patterns differed within and between herds. These findings emphasize the need to choose preventive strategies for each individual herd. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Using open-access taxonomic and spatial information to create a comprehensive database for the study of mammalian and avian livestock and pet infections.

PubMed

McIntyre, K M; Setzkorn, C; Wardeh, M; Hepworth, P J; Radford, A D; Baylis, M

2014-10-01

What are all the species of pathogen that affect our livestock? As 6 out of every 10 human pathogens came from animals, with a good number from livestock and pets, it seems likely that the majority that emerge in the future, and which could threaten or devastate human health, will come from animals. Only 10 years ago, the first comprehensive pathogen list was compiled for humans; we still have no equivalent for animals. Here we describe the creation of a novel pathogen database, and present outputs from the database that demonstrate its value. The ENHanCEd Infectious Diseases database (EID2) is open-access and evidence-based, and it describes the pathogens of humans and animals, their host and vector species, and also their global occurrence. The EID2 systematically collates information on pathogens into a single resource using evidence from the NCBI Taxonomy database, the NCBI Nucleotide database, the NCBI MeSH (Medical Subject Headings) library and PubMed. Information about pathogens is assigned using data-mining of meta-data and semi-automated literature searches. Here we focus on 47 mammalian and avian hosts, including humans and animals commonly used in Europe as food or kept as pets. Currently, the EID2 evidence suggests that: • Within these host species, 793 (30.5%) pathogens were bacteria species, 395 (15.2%) fungi, 705 (27.1%) helminths, 372 (14.3%) protozoa and 332 (12.8%) viruses. • The odds of pathogens being emerging compared to not emerging differed by taxonomic division, and increased when pathogens had greater numbers of host species associated with them, and were zoonotic rather than non-zoonotic. • The odds of pathogens being zoonotic compared to non-zoonotic differed by taxonomic division and also increased when associated with greater host numbers. • The pathogens affecting the greatest number of hosts included: Escherichia coli, Giardia intestinalis, Toxoplasma gondii, Anaplasma phagocytophilum, Cryptosporidium parvum, Rabies virus, Staphylococcus aureus, Neospora caninum and Echinococcus granulosus. • The pathogens of humans and domestic animal hosts are characterised by 4223 interactions between pathogen and host species, with the greatest number found in: humans, sheep/goats, cattle, small mammals, pigs, dogs and equids. • The number of pathogen species varied by European country. The odds of a pathogen being found in Europe compared to the rest of the world differed by taxonomic division, and increased if they were emerging compared to not emerging, or had a larger number of host species associated with them. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Resistance to multiple soil-borne pathogens of the Pacific Northwest is co-located in a wheat recombinant inbred line population

USDA-ARS?s Scientific Manuscript database

Soil-borne pathogens of the Pacific Northwest decrease yields in both spring and winter wheat. Pathogens of economic importance include Fusarium culmorum, Pratylenchus neglectus, P. thornei, and Rhizoctonia solani AG8. Few options are available to growers to manage these pathogens and reduce yield l...

pH Dependency of sclerotial development and pathogenicity revealed by using genetically defined oxalate-minus mutants of Sclerotinia sclerotiorum

USDA-ARS?s Scientific Manuscript database

The devastating plant pathogen Sclerotinia sclerotiorum produces copious (up to 50mM) amounts of oxalic acid, which, for over a quarter century, has been claimed as the pathogenicity determinant based on UV-induced mutants that concomitantly lost oxalate production and pathogenicity. Such a claim wa...

78 FR 76628 - Draft Risk Profile on Pathogens and Filth in Spices: Availability; Extension of Comment Period

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-18

...] Draft Risk Profile on Pathogens and Filth in Spices: Availability; Extension of Comment Period AGENCY... Profile on Pathogens and Filth in Spices: Availability'' that appeared in the Federal Register of November... Risk Profile on Pathogens and Filth in Spices: Availability.'' The notice provided a 60-day comment...

The Wor1-like protein Fgp1 regulates pathogenicity, toxin synthesis and reproduction in the phytopathogenic fungus Fusarium graminearum

USDA-ARS?s Scientific Manuscript database

WOR1 is a gene for a conserved fungal regulatory protein controlling the dimorphic switch and pathogenicity in Candida albicans and its ortholog in the plant pathogen Fusarium oxysporum, called SGE1, is also required for pathogenicity and expression of plant effector proteins. F. graminearum, an imp...

Influence of oak woodland composition and structure on infection by Phytophthora ramorum

Treesearch

Nathan Rank; Hall Cushman; Brian Anacker; David Rizzo; Ross Meentemeyer

2008-01-01

Introduced plant pathogens have major ecological impacts in many parts of the world. While the spread of pathogens can be strongly mediated by the composition and structure of local host plant communities, little is known about effects of plant community structure on invasion dynamics of introduced pathogens. The progress of infection by the invasive pathogen ...

Optimized co-extraction and quantification of DNA from enteric pathogens in surface water samples near produce fields in California

USDA-ARS?s Scientific Manuscript database

Pathogen contamination of surface water is a health hazard in agricultural environments primarily due to the potential for contamination of crops. Furthermore, pathogen levels in surface water are often unreported or under reported due to difficulty with culture of the bacteria. The pathogens are of...

Assessing pathogen and insect succession functions in forest ecosystems

Treesearch

Susan K. Hagle; Sandra J. Kegley; Stephen B. Williams

1995-01-01

The pilot test of a method to assess the ecological function of pathogens and insects in forests is reported. The analysis is a practical application of current ecosystem management theory.The influences of pathogens and insects on forest succession are measured by relating successional transition rates and types to conditions for pathogen and insect activities which...

Tracing the role of human civilization in the globalization of plant pathogens

Treesearch

Alberto Santini; Andrew Liebhold; Duccio Migliorini; Steve Woodward

2018-01-01

Co-evolution between plants and parasites, including herbivores and pathogens, has arguably generated much of Earth’s biological diversity. Within an ecosystem, coevolution of plants and pathogens is a stepwise reciprocal evolutionary interaction: epidemics result in intense selection pressures on both host and pathogen populations, ultimately allowing long-term...

Chapter A7. Section 7.3. Protozoan Pathogens

USGS Publications Warehouse

Bushon, Rebecca N.; Francy, Donna S.

2003-01-01

Protozoan pathogens are widely distributed in the aquatic environment. Cryptosporidium and Giardia are the principal protozoan pathogens that are known to affect the acceptability of water supplies for public use within the United States. A sampling program for protozoan pathogens should be conducted over an extended period of time because of cyclical and seasonal variations in their concentrations in the environment. This report provides information on the equipment, sampling protocols, and laboratory method that are in standard use by U.S. Geological Survey (USGS) personnel for the collection of data on protozoan pathogens.

Effector-triggered defence against apoplastic fungal pathogens

PubMed Central

Stotz, Henrik U.; Mitrousia, Georgia K.; de Wit, Pierre J.G.M.; Fitt, Bruce D.L.

2014-01-01

R gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed ‘effector-triggered defence’ (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of crops. PMID:24856287

Development of a Multiplex PCR Method to Detect Fungal Pathogens for Quarantine on Exported Cacti

PubMed Central

Cho, Hyun ji; Hong, Seong Won; Kim, Hyun-ju; Kwak, Youn-Sig

2016-01-01

Major diseases in grafted cacti have been reported and Fusarium oxysporum, Bipolaris cactivora, Phytophthora spp. and Collectotrichum spp. are known as causal pathogens. These pathogens can lead to plant death after infection. Therefore, some European countries have quarantined imported cacti that are infected with specific fungal pathogens. Consequently, we developed PCR detection methods to identify four quarantined fungal pathogens and reduce export rejection rates of Korean grafted cacti. The pathogen specific primer sets F.oF-F.oR, B.CF-B.CR, P.nF-P.nR, and P.cF-P.CR were tested for F. oxysporum, B. cactivora, P. nicotinae, and P. cactorum, respectively. The F.oF-F.oR primer set was designed from the Fusarium ITS region; the B.CF-B.CR and P.nF-P.nR primers respectively from Bipolaris and Phytophthora ITS1; and the P.cF-P.CR primer set from the Ypt1protein gene region. The quarantine fungal pathogen primer pairs were amplified to the specific number of base pairs in each of the following fungal pathogens: 210-bp (F. oxysporum), 510-bp (B. cactivora), 313-bp (P. nicotinae), and 447-bp (P. cactorum). The detection limit for the mono- and multiplex PCR primer sets was 0.1 ng of template DNA under in vitro conditions. Therefore, each primer set successfully diagnosed contamination of quarantine pathogens in export grafted cacti. Consequently, our methodology is a viable tool to screen contamination of the fungal pathogen in exported grafted cacti. PMID:26889115

Plasmodesmal regulation during plant-pathogen interactions.

PubMed

Cheval, Cecilia; Faulkner, Christine

2018-01-01

Contents Summary 62 I. Introduction 62 II. Plasmodesmal regulation is an innate defence response 63 III. Reactive oxygen species regulate plasmodesmal function 63 IV. Plasmodesmal regulation by and of defence-associated small molecules 64 V. Plasmodesmata facilitate systemic defence signalling 64 VI. Virulent pathogens exploit plasmodesmata 66 VII. Outlook 66 Acknowledgements 66 References 66 SUMMARY: Plasmodesmata (PD) are plasma membrane-lined pores that connect neighbouring plant cells, bridging the cell wall and establishing cytoplasmic and membrane continuity between cells. PD are dynamic structures regulated by callose deposition in a variety of stress and developmental contexts. This process crudely controls the aperture of the pore and thus the flux of molecules between cells. During pathogen infection, plant cells initiate a range of immune responses and it was recently identified that, following perception of fungal and bacterial pathogens, plant cells initially close their PD. Systemic defence responses depend on the spread of signals between cells, raising questions about whether PD are in different functional states during different immune responses. It is well established that viral pathogens exploit PD to spread between cells, but it has more recently been identified that protein effectors secreted by fungal pathogens can spread between host cells via PD. It is possible that many classes of pathogens specifically target PD to aid infection, which would infer antagonistic regulation of PD by host and pathogen. How PD regulation benefits both host immune responses and pathogen infection is an important question and demands that we examine the multicellular nature of plant-pathogen interactions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Comparative Genomics of a Plant-Pathogenic Fungus, Pyrenophora tritici-repentis, Reveals Transduplication and the Impact of Repeat Elements on Pathogenicity and Population Divergence

PubMed Central

Manning, Viola A.; Pandelova, Iovanna; Dhillon, Braham; Wilhelm, Larry J.; Goodwin, Stephen B.; Berlin, Aaron M.; Figueroa, Melania; Freitag, Michael; Hane, James K.; Henrissat, Bernard; Holman, Wade H.; Kodira, Chinnappa D.; Martin, Joel; Oliver, Richard P.; Robbertse, Barbara; Schackwitz, Wendy; Schwartz, David C.; Spatafora, Joseph W.; Turgeon, B. Gillian; Yandava, Chandri; Young, Sarah; Zhou, Shiguo; Zeng, Qiandong; Grigoriev, Igor V.; Ma, Li-Jun; Ciuffetti, Lynda M.

2013-01-01

Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes. PMID:23316438

Redefining disease emergence to improve prioritization and macro-ecological analyses.

PubMed

Rosenthal, Samantha R; Ostfeld, Richard S; McGarvey, Stephen T; Lurie, Mark N; Smith, Katherine F

2015-12-01

Microbial infections are as old as the hosts they sicken, but interest in the emergence of pathogens and the diseases they cause has been accelerating rapidly. The term 'emerging infectious disease' was coined in the mid-1900s to describe changes in disease dynamics in the modern era. Both the term and the phenomena it is meant to characterize have evolved and diversified over time, leading to inconsistencies and confusion. Here, we review the evolution of the term 'emerging infectious disease' (EID) in the literature as applied to human hosts. We examine the pathways (e.g., speciation or strain differentiation in the causative agent vs. rapid geographic expansion of an existing pathogen) by which diseases emerge. We propose a new framework for disease and pathogen emergence to improve prioritization. And we illustrate how the operational definition of an EID affects conclusions concerning the pathways by which diseases emerge and the ecological and socioeconomic drivers that elicit emergence. As EIDs appear to be increasing globally, and resources for science level off or decline, the research community is pushed to prioritize its focus on the most threatening diseases, riskiest potential pathogens, and the places they occur. The working definition of emerging infectious diseases and pathogens plays a crucial role in prioritization, but we argue that the current definitions may be impeding these efforts. We propose a new framework for classifying pathogens and diseases as "emerging" that distinguishes EIDs from emerging pathogens and novel potential pathogens. We suggest prioritization of: 1) EIDs for adaptation and mitigation, 2) emerging pathogens for preventive measures, and 3) novel potential pathogens for intensive surveillance.

Pathogen Webs in Collapsing Honey Bee Colonies

PubMed Central

Cornman, R. Scott; Tarpy, David R.; Chen, Yanping; Jeffreys, Lacey; Lopez, Dawn; Pettis, Jeffery S.; vanEngelsdorp, Dennis; Evans, Jay D.

2012-01-01

Recent losses in honey bee colonies are unusual in their severity, geographical distribution, and, in some cases, failure to present recognized characteristics of known disease. Domesticated honey bees face numerous pests and pathogens, tempting hypotheses that colony collapses arise from exposure to new or resurgent pathogens. Here we explore the incidence and abundance of currently known honey bee pathogens in colonies suffering from Colony Collapse Disorder (CCD), otherwise weak colonies, and strong colonies from across the United States. Although pathogen identities differed between the eastern and western United States, there was a greater incidence and abundance of pathogens in CCD colonies. Pathogen loads were highly covariant in CCD but not control hives, suggesting that CCD colonies rapidly become susceptible to a diverse set of pathogens, or that co-infections can act synergistically to produce the rapid depletion of workers that characterizes the disorder. We also tested workers from a CCD-free apiary to confirm that significant positive correlations among pathogen loads can develop at the level of individual bees and not merely as a secondary effect of CCD. This observation and other recent data highlight pathogen interactions as important components of bee disease. Finally, we used deep RNA sequencing to further characterize microbial diversity in CCD and non-CCD hives. We identified novel strains of the recently described Lake Sinai viruses (LSV) and found evidence of a shift in gut bacterial composition that may be a biomarker of CCD. The results are discussed with respect to host-parasite interactions and other environmental stressors of honey bees. PMID:22927991

Extensive Metabolic Remodeling Differentiates Non-pathogenic and Pathogenic Growth Forms of the Dimorphic Pathogen Talaromyces marneffei

PubMed Central

Pasricha, Shivani; MacRae, James I.; Chua, Hwa H.; Chambers, Jenny; Boyce, Kylie J.; McConville, Malcolm J.; Andrianopoulos, Alex

2017-01-01

Fungal infections are an increasing public health problem, particularly in immunocompromised individuals. While these pathogenic fungi show polyphyletic origins with closely related non-pathogenic species, many undergo morphological transitions to produce pathogenic cell types that are associated with increased virulence. However, the characteristics of these pathogenic cells that contribute to virulence are poorly defined. Talaromyces marneffei grows as a non-pathogenic hyphal form at 25°C but undergoes a dimorphic transition to a pathogenic yeast form at 37°C in vitro and following inhalation of asexual conidia by a host. Here we show that this transition is associated with major changes in central carbon metabolism, and that these changes are correlated with increased virulence of the yeast form. Comprehensive metabolite profiling and 13C-labeling studies showed that hyphal cells exhibited very active glycolytic metabolism and contain low levels of internal carbohydrate reserves. In contrast, yeast cells fully catabolized glucose in the mitochondrial TCA cycle, and store excess glucose in large intracellular pools of trehalose and mannitol. Inhibition of the yeast TCA cycle inhibited replication in culture and in host cells. Yeast, but not hyphae, were also able to use myo-inositol and amino acids as secondary carbon sources, which may support their survival in host macrophages. These analyses suggest that T. marneffei yeast cells exhibit a more efficient oxidative metabolism and are capable of utilizing a diverse range of carbon sources, which contributes to their virulence in animal tissues, highlighting the importance of dimorphic switching in pathogenic yeast. PMID:28861398

Extensive Metabolic Remodeling Differentiates Non-pathogenic and Pathogenic Growth Forms of the Dimorphic Pathogen Talaromyces marneffei.

PubMed

Pasricha, Shivani; MacRae, James I; Chua, Hwa H; Chambers, Jenny; Boyce, Kylie J; McConville, Malcolm J; Andrianopoulos, Alex

2017-01-01

Fungal infections are an increasing public health problem, particularly in immunocompromised individuals. While these pathogenic fungi show polyphyletic origins with closely related non-pathogenic species, many undergo morphological transitions to produce pathogenic cell types that are associated with increased virulence. However, the characteristics of these pathogenic cells that contribute to virulence are poorly defined. Talaromyces marneffei grows as a non-pathogenic hyphal form at 25°C but undergoes a dimorphic transition to a pathogenic yeast form at 37°C in vitro and following inhalation of asexual conidia by a host. Here we show that this transition is associated with major changes in central carbon metabolism, and that these changes are correlated with increased virulence of the yeast form. Comprehensive metabolite profiling and 13 C-labeling studies showed that hyphal cells exhibited very active glycolytic metabolism and contain low levels of internal carbohydrate reserves. In contrast, yeast cells fully catabolized glucose in the mitochondrial TCA cycle, and store excess glucose in large intracellular pools of trehalose and mannitol. Inhibition of the yeast TCA cycle inhibited replication in culture and in host cells. Yeast, but not hyphae, were also able to use myo -inositol and amino acids as secondary carbon sources, which may support their survival in host macrophages. These analyses suggest that T. marneffei yeast cells exhibit a more efficient oxidative metabolism and are capable of utilizing a diverse range of carbon sources, which contributes to their virulence in animal tissues, highlighting the importance of dimorphic switching in pathogenic yeast.

A plant EPF-type zinc-finger protein, CaPIF1, involved in defence against pathogens.

PubMed

Oh, Sang-Keun; Park, Jeong Mee; Joung, Young Hee; Lee, Sanghyeob; Chung, Eunsook; Kim, Soo-Yong; Yu, Seung Hun; Choi, Doil

2005-05-01

SUMMARY To understand better the defence responses of plants to pathogen attack, we challenged hot pepper plants with bacterial pathogens and identified transcription factor-encoding genes whose expression patterns were altered during the subsequent hypersensitive response. One of these genes, CaPIF1 (Capsicum annuum Pathogen-Induced Factor 1), was characterized further. This gene encodes a plant-specific EPF-type protein that contains two Cys(2)/His(2) zinc fingers. CaPIF1 expression was rapidly and specifically induced when pepper plants were challenged with bacterial pathogens to which they are resistant. In contrast, challenge with a pathogen to which the plants are susceptible only generated weak CaPIF1 expression. CaPIF1 expression was also strongly induced in pepper leaves by the exogenous application of ethephon, an ethylene-releasing compound, and salicylic acid, whereas methyl jasmonate had only moderate effects. CaPIF1 localized to the nuclei of onion epidermis when expressed as a CaPIF1-smGFP fusion protein. Transgenic tobacco plants over-expressing CaPIF1 driven by the CaMV 35S promoter showed increased resistance to challenge with a tobacco-specific pathogen or non-host bacterial pathogens. These plants also showed constitutive up-regulation of multiple defence-related genes. Moreover, virus-induced silencing of the CaPIF1 orthologue in Nicotiana benthamiana enhanced susceptibility to the same host or non-host bacterial pathogens. These observations provide evidence that an EPF-type Cys(2)/His(2) zinc-finger protein plays a crucial role in the activation of the pathogen defence response in plants.

Comparative Genomics of a Plant-Pathogenic Fungus, Pyrenophora tritici-repentis, Reveals Transduplication and the Impact of Repeat Elements on Pathogenicity and Population Divergence

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

Manning, Viola A.; Pandelova, Iovanna; Dhillon, Braham

2012-08-16

Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11more » chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes.« less

Actionable exomic incidental findings in 6503 participants: challenges of variant classification

PubMed Central

Amendola, Laura M.; Dorschner, Michael O.; Robertson, Peggy D.; Salama, Joseph S.; Hart, Ragan; Shirts, Brian H.; Murray, Mitzi L.; Tokita, Mari J.; Gallego, Carlos J.; Kim, Daniel Seung; Bennett, James T.; Crosslin, David R.; Ranchalis, Jane; Jones, Kelly L.; Rosenthal, Elisabeth A.; Jarvik, Ella R.; Itsara, Andy; Turner, Emily H.; Herman, Daniel S.; Schleit, Jennifer; Burt, Amber; Jamal, Seema M.; Abrudan, Jenica L.; Johnson, Andrew D.; Conlin, Laura K.; Dulik, Matthew C.; Santani, Avni; Metterville, Danielle R.; Kelly, Melissa; Foreman, Ann Katherine M.; Lee, Kristy; Taylor, Kent D.; Guo, Xiuqing; Crooks, Kristy; Kiedrowski, Lesli A.; Raffel, Leslie J.; Gordon, Ora; Machini, Kalotina; Desnick, Robert J.; Biesecker, Leslie G.; Lubitz, Steven A.; Mulchandani, Surabhi; Cooper, Greg M.; Joffe, Steven; Richards, C. Sue; Yang, Yaoping; Rotter, Jerome I.; Rich, Stephen S.; O’Donnell, Christopher J.; Berg, Jonathan S.; Spinner, Nancy B.; Evans, James P.; Fullerton, Stephanie M.; Leppig, Kathleen A.; Bennett, Robin L.; Bird, Thomas; Sybert, Virginia P.; Grady, William M.; Tabor, Holly K.; Kim, Jerry H.; Bamshad, Michael J.; Wilfond, Benjamin; Motulsky, Arno G.; Scott, C. Ronald; Pritchard, Colin C.; Walsh, Tom D.; Burke, Wylie; Raskind, Wendy H.; Byers, Peter; Hisama, Fuki M.; Rehm, Heidi; Nickerson, Debbie A.; Jarvik, Gail P.

2015-01-01

Recommendations for laboratories to report incidental findings from genomic tests have stimulated interest in such results. In order to investigate the criteria and processes for assigning the pathogenicity of specific variants and to estimate the frequency of such incidental findings in patients of European and African ancestry, we classified potentially actionable pathogenic single-nucleotide variants (SNVs) in all 4300 European- and 2203 African-ancestry participants sequenced by the NHLBI Exome Sequencing Project (ESP). We considered 112 gene-disease pairs selected by an expert panel as associated with medically actionable genetic disorders that may be undiagnosed in adults. The resulting classifications were compared to classifications from other clinical and research genetic testing laboratories, as well as with in silico pathogenicity scores. Among European-ancestry participants, 30 of 4300 (0.7%) had a pathogenic SNV and six (0.1%) had a disruptive variant that was expected to be pathogenic, whereas 52 (1.2%) had likely pathogenic SNVs. For African-ancestry participants, six of 2203 (0.3%) had a pathogenic SNV and six (0.3%) had an expected pathogenic disruptive variant, whereas 13 (0.6%) had likely pathogenic SNVs. Genomic Evolutionary Rate Profiling mammalian conservation score and the Combined Annotation Dependent Depletion summary score of conservation, substitution, regulation, and other evidence were compared across pathogenicity assignments and appear to have utility in variant classification. This work provides a refined estimate of the burden of adult onset, medically actionable incidental findings expected from exome sequencing, highlights challenges in variant classification, and demonstrates the need for a better curated variant interpretation knowledge base. PMID:25637381

What is the risk for exposure to vector-borne pathogens in United States national parks?

PubMed

Eisen, Lars; Wong, David; Shelus, Victoria; Eisen, Rebecca J

2013-03-01

United States national parks attract > 275 million visitors annually and collectively present risk of exposure for staff and visitors to a wide range of arthropod vector species (most notably fleas, mosquitoes, and ticks) and their associated bacterial, protozoan, or viral pathogens. We assessed the current state of knowledge for risk of exposure to vector-borne pathogens in national parks through a review of relevant literature, including internal National Park Service documents and organismal databases. We conclude that, because of lack of systematic surveillance for vector-borne pathogens in national parks, the risk of pathogen exposure for staff and visitors is unclear. Existing data for vectors within national parks were not based on systematic collections and rarely include evaluation for pathogen infection. Extrapolation of human-based surveillance data from neighboring communities likely provides inaccurate estimates for national parks because landscape differences impact transmission of vector-borne pathogens and human-vector contact rates likely differ inside versus outside the parks because of differences in activities or behaviors. Vector-based pathogen surveillance holds promise to define when and where within national parks the risk of exposure to infected vectors is elevated. A pilot effort, including 5-10 strategic national parks, would greatly improve our understanding of the scope and magnitude of vector-borne pathogen transmission in these high-use public settings. Such efforts also will support messaging to promote personal protection measures and inform park visitors and staff of their responsibility for personal protection, which the National Park Service preservation mission dictates as the core strategy to reduce exposure to vector-borne pathogens in national parks.

Microbial antagonism as a potential solution for controlling selected root pathogens of crops

NASA Astrophysics Data System (ADS)

Cooper, Sarah; Agnew, Linda; Pereg, Lily

2016-04-01

Root pathogens of crops can cause large reduction in yield, however, there is a limited range of effective methods to control such pathogens. Soilborne pathogens that infect roots often need to survive in the rhizosphere, where there is high competition from other organisms. In such hot spots of microbial activity and growth, supported by root exudates, microbes have evolved antagonistic mechanisms that give them competitive advantages in winning the limited resources. Among these mechanisms is antibiosis, with production of some significant antifungal compounds including, antibiotics, volatile organic compounds, hydrogen cyanide and lytic enzymes. Some of these mechanisms may suppress disease through controlling the growth of root pathogens. In this project we isolated various fungi and bacteria that suppress the growth of cotton pathogens in vitro. The pathogen-suppressive microbes were isolated from cotton production soils that are under different management strategies, with and without the use of organic amendments. The potential of pathogen-suppressing microbes for controlling the black root rot disease, caused by the soilborne pathogen Thielaviopsis basicola, was confirmed using soil assays. We identified isolates with potential use as inoculant for cotton production in Australia. Having isolated a diverse group of antagonistic microbes enhances the probability that some would survive well in the soil and provide an alternative approach to address the problem of root disease affecting agricultural crops.

Individual and combined effects of multiple pathogens on Pacific treefrogs.

PubMed

Romansic, John M; Johnson, Pieter T J; Searle, Catherine L; Johnson, James E; Tunstall, Tate S; Han, Barbara A; Rohr, Jason R; Blaustein, Andrew R

2011-08-01

In nature, individual hosts often encounter multiple pathogens simultaneously, which can lead to additive, antagonistic, or synergistic effects on hosts. Synergistic effects on infection prevalence or severity could greatly affect host populations. However, ecologists and managers often overlook the influence of pathogen combinations on hosts. This is especially true in amphibian conservation, even though multiple pathogens coexist within amphibian populations, and several pathogens have been implicated in amphibian population declines and extinctions. Using an amphibian host, Pseudacris regilla (Pacific treefrog), we experimentally investigated interactive effects among three pathogens: the trematode Ribeiroia sp. (hereafter, Ribeiroia), the fungus Batrachochytrium dendrobatidis (hereafter, BD), and the water mold Achlya flagellata. We detected no effects of A. flagellata, but did find effects of Ribeiroia and BD that varied depending on context. Low doses of Ribeiroia caused relatively few malformations, while higher Ribeiroia doses caused numerous deformities dominated by missing and reduced limbs and limb elements. Exposure to low doses of BD accelerated larval host development, despite there being no detectable BD infections, while exposure to higher BD doses caused infection but did not alter developmental rate. Hosts exposed to both Ribeiroia and BD exhibited the highest mortality, although overall evidence of interactive effects of multiple pathogens was limited. We suggest further research on the influence of multi-pathogen assemblages on amphibians, particularly under a variety of ecological conditions and with a wider diversity of hosts and pathogens.

Pathogenicity and infection strategies of the fire blight pathogen Erwinia amylovora in Rosaceae: state of the art.

PubMed

Vrancken, K; Holtappels, M; Schoofs, H; Deckers, T; Valcke, R

2013-05-01

Plants are host to a large amount of pathogenic bacteria. Fire blight, caused by the bacterium Erwinia amylovora, is an important disease in Rosaceae. Pathogenicity of E. amylovora is greatly influenced by the production of exopolysaccharides, such as amylovoran, and the use of the type III secretion system, which enables bacteria to penetrate host tissue and cause disease. When infection takes place, plants have to rely on the ability of each cell to recognize the pathogen and the signals emanating from the infection site in order to generate several defence mechanisms. These mechanisms consist of physical barriers and the production of antimicrobial components, both in a preformed and an inducible manner. Inducible defence responses are activated upon the recognition of elicitor molecules by plant cell receptors, either derived from invading micro-organisms or from pathogen-induced degradation of plant tissue. This recognition event triggers a signal transduction cascade, leading to a range of defence responses [reactive oxygen species (ROS), plant hormones, secondary metabolites, …] and redeployment of cellular energy in a fast, efficient and multiresponsive manner, which prevents further pathogen ingress. This review highlights the research that has been performed during recent years regarding this specific plant-pathogen interaction between Erwinia amylovora and Rosaceae, with a special emphasis on the pathogenicity and the infection strategy of E. amylovora and the possible defence mechanisms of the plant against this disease.

Arthropods and associated arthropod-borne diseases transmitted by migrating birds. The case of ticks and tick-borne pathogens.

PubMed

Sparagano, Olivier; George, David; Giangaspero, Annunziata; Špitalská, Eva

2015-09-30

Geographic spread of parasites and pathogens poses a constant risk to animal health and welfare, particularly given that climate change is expected to potentially expand appropriate ranges for many key species. The spread of deleterious organisms via trade routes and human travelling is relatively closely controlled, though represents only one possible means of parasite/pathogen distribution. The transmission via natural parasite/pathogen movement between geographic locales, is far harder to manage. Though the extent of such movement may be limited by the relative inability of many parasites and pathogens to actively migrate, passive movement over long distances may still occur via migratory hosts. This paper reviews the potential role of migrating birds in the transfer of ectoparasites and pathogens between geographic locales, focusing primarily on ticks. Bird-tick-pathogen relationships are considered, and evidence provided of long-range parasite/pathogen transfer from one location to another during bird migration events. As shown in this paper not only many different arthropod species are carried by migrating birds but consequently these pests carry many different pathogens species which can be transmitted to the migrating birds or to other animal species when those arthropods are dropping during these migrations. Data available from the literature are provided highlighting the need to understand better dissemination paths and disease epidemiology. Copyright © 2015 Elsevier B.V. All rights reserved.

Targeting of the hydrophobic metabolome by pathogens.

PubMed

Helms, J Bernd; Kaloyanova, Dora V; Strating, Jeroen R P; van Hellemond, Jaap J; van der Schaar, Hilde M; Tielens, Aloysius G M; van Kuppeveld, Frank J M; Brouwers, Jos F

2015-05-01

The hydrophobic molecules of the metabolome - also named the lipidome - constitute a major part of the entire metabolome. Novel technologies show the existence of a staggering number of individual lipid species, the biological functions of which are, with the exception of only a few lipid species, unknown. Much can be learned from pathogens that have evolved to take advantage of the complexity of the lipidome to escape the immune system of the host organism and to allow their survival and replication. Different types of pathogens target different lipids as shown in interaction maps, allowing visualization of differences between different types of pathogens. Bacterial and viral pathogens target predominantly structural and signaling lipids to alter the cellular phenotype of the host cell. Fungal and parasitic pathogens have complex lipidomes themselves and target predominantly the release of polyunsaturated fatty acids from the host cell lipidome, resulting in the generation of eicosanoids by either the host cell or the pathogen. Thus, whereas viruses and bacteria induce predominantly alterations in lipid metabolites at the host cell level, eukaryotic pathogens focus on interference with lipid metabolites affecting systemic inflammatory reactions that are part of the immune system. A better understanding of the interplay between host-pathogen interactions will not only help elucidate the fundamental role of lipid species in cellular physiology, but will also aid in the generation of novel therapeutic drugs. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Immune evasion by pathogens of bovine respiratory disease complex.

PubMed

Srikumaran, Subramaniam; Kelling, Clayton L; Ambagala, Aruna

2007-12-01

Bovine respiratory tract disease is a multi-factorial disease complex involving several viruses and bacteria. Viruses that play prominent roles in causing the bovine respiratory disease complex include bovine herpesvirus-1, bovine respiratory syncytial virus, bovine viral diarrhea virus and parinfluenza-3 virus. Bacteria that play prominent roles in this disease complex are Mannheimia haemolytica and Mycoplasma bovis. Other bacteria that infect the bovine respiratory tract of cattle are Histophilus (Haemophilus) somni and Pasteurella multocida. Frequently, severe respiratory tract disease in cattle is associated with concurrent infections of these pathogens. Like other pathogens, the viral and bacterial pathogens of this disease complex have co-evolved with their hosts over millions of years. As much as the hosts have diversified and fine-tuned the components of their immune system, the pathogens have also evolved diverse and sophisticated strategies to evade the host immune responses. These pathogens have developed intricate mechanisms to thwart both the innate and adaptive arms of the immune responses of their hosts. This review presents an overview of the strategies by which the pathogens suppress host immune responses, as well as the strategies by which the pathogens modify themselves or their locations in the host to evade host immune responses. These immune evasion strategies likely contribute to the failure of currently-available vaccines to provide complete protection to cattle against these pathogens.

Role of commercial probiotic strains against human pathogen adhesion to intestinal mucus.

PubMed

Collado, M C; Meriluoto, J; Salminen, S

2007-10-01

The aims of this study present were to assess and to evaluate in vitro the abilities of commercial probiotic strains derived from fermented milk products and related sources currently marketed in European countries, to inhibit, compete and displace the adhesion of selected potential pathogens to immobilized human mucus. The adhesion was assessed by measuring the radioactivity of bacteria adhered to the human mucus. We tested 12 probiotic strains against eight selected pathogens. All strains tested were able to adhere to mucus. All probiotic strains tested were able to inhibit and displace (P<0.05) the adhesion of Bacteroides, Clostridium, Staphylococcus and Enterobacter. In addition, the abilities to inhibit and to displace adhered pathogens depended on both the probiotic and the pathogen strains tested suggesting that several complementary mechanisms are implied in the processes. Our results indicate the need for a case-by-case assessment in order to select strains with the ability to inhibit or displace a specific pathogen. Probiotics could be useful to correct deviations observed in intestinal microbiota associated with specific diseases and also, to prevent pathogen infections. The competitive exclusion properties of probiotics as well as their ability to displace and inhibit pathogens are the most importance for therapeutic manipulation of the enteric microbiota. The application of such strategies could contribute to expand the beneficial properties on human health against pathogen infection.

Comparative analysis of phylogenetic relationships, morphologies, and pathogenicities among Curvularia lunata isolates from maize in China.

PubMed

Liu, T; Zhao, F Z; Wang, Y Y; Hou, J M; Liu, L Z; Shen, Y Q; Liu, Z; Zhang, H T; Zuo, Y H

2015-10-16

To understand the effects of disease-resistant maize varieties and new cropping systems on the population of Curvularia lunata, 52 isolates of C. lunata were collected in China from 2011 to 2013. The isolates were analyzed in terms of phylogenetic relationships, morphology, and pathogenicity. Phylogenetic analysis showed that the 52 isolates clustered into 2 distinct clusters with further subdivisions, suggesting the emergence of new genetic divergence within C. lunata. Results of morphology and pathogenicity analyses demonstrated that there were significant differences among these isolates: 27 isolates were classified as fast growing, 5 as slow growing, and 20 as moderate growing. Three isolates had white-colored colonies, 13 had yellowish green-colored colonies, and the remaining isolates had dark green-colored colonies. Furthermore, conidiation rates were assessed: 30 isolates were characterized as having low conidiation rates, 15 as having medium conidiation rates, and the remaining 7 isolates as having high conidiation rates. Eleven of the isolates appeared to be strongly pathogenic against maize, 15 isolates proved to be weakly pathogenic against maize, and the remaining isolates were regarded to be moderately pathogenic. Interestingly, correlation analysis demonstrated a negative correlation between the growth rate and the pathogenicity of the isolates, while a positive correlation was observed between the conidiation rate and the pathogenicity. No correlation was observed between the colony color and the pathogenicity of the isolates.

High Variation in Pathogenicity of Genetically Closely Related Strains of Xanthomonas albilineans, the Sugarcane Leaf Scald Pathogen, in Guadeloupe.

PubMed

Champoiseau, P; Daugrois, J-H; Pieretti, I; Cociancich, S; Royer, M; Rott, P

2006-10-01

ABSTRACT Pathogenicity of 75 strains of Xanthomonas albilineans from Guadeloupe was assessed by inoculation of sugarcane cv. B69566, which is susceptible to leaf scald, and 19 of the strains were selected as representative of the variation in pathogenicity observed based on stalk colonization. In vitro production of albicidin varied among these 19 strains, but the restriction fragment length polymorphism pattern of their albicidin biosynthesis genes was identical. Similarly, no genomic variation was found among strains by pulsed-field gel electrophoresis. Some variation among strains was found by amplified fragment length polymorphism, but no relationship between this genetic variation and variation in pathogenicity was found. Only 3 (pilB, rpfA, and xpsE) of 40 genes involved in pathogenicity of bacterial species closely related to X. albilineans could be amplified by polymerase chain reaction from total genomic DNA of all nine strains tested of X. albilineans differing in pathogenicity in Guadeloupe. Nucleotide sequences of these genes were 100% identical among strains, and a phylogenetic study with these genes and housekeeping genes efp and ihfA suggested that X. albilineans is on an evolutionary road between the X. campestris group and Xylella fastidiosa, another vascular plant pathogen. Sequencing of the complete genome of Xanthomonas albilineans could be the next step in deciphering molecular mechanisms involved in pathogenicity of X. albilineans.

Development of a mathematical model for mechanical transmission of trypanosomes and other pathogens of cattle transmitted by tabanids.

PubMed

Desquesnes, Marc; Biteau-Coroller, Fabienne; Bouyer, Jérémy; Dia, Mamadou Lamine; Foil, Lane

2009-02-01

Mechanical transmission of pathogens by biting insects is a non-specific phenomenon in which pathogens are transmitted from the blood of an infected host to another host during interrupted feeding of the insects. A large range of pathogens can be mechanically transmitted, e.g. hemoparasites, bacteria and viruses. Some pathogens are almost exclusively mechanically transmitted, while others are also cyclically transmitted. For agents transmitted both cyclically and mechanically (mixed transmission), such as certain African pathogenic trypanosomes, the relative impact of mechanical versus cyclical transmission is essentially unknown. We have developed a mathematical model of pathogen transmission by a defined insect population to evaluate the importance of mechanical transmission. Based on a series of experiments aimed at demonstrating mechanical transmission of African trypanosomes by tabanids, the main parameters of the model were either quantified (host parasitaemia, mean individual insect burden, initial prevalence of infection) or estimated (unknown parameters). This model allows us to simulate the evolution of pathogen prevalence under various predictive circumstances, including control measures and could be used to assess the risk of mechanical transmission under field conditions. If adjustments of parameters are provided, this model could be generalized to other pathogenic agents present in the blood of their hosts (Bovine Leukemia virus, Anaplasma, etc.) or other biting insects such as biting muscids (stomoxyines) and hippoboscids.

The Effect of Ongoing Exposure Dynamics in Dose Response Relationships

PubMed Central

Pujol, Josep M.; Eisenberg, Joseph E.; Haas, Charles N.; Koopman, James S.

2009-01-01

Characterizing infectivity as a function of pathogen dose is integral to microbial risk assessment. Dose-response experiments usually administer doses to subjects at one time. Phenomenological models of the resulting data, such as the exponential and the Beta-Poisson models, ignore dose timing and assume independent risks from each pathogen. Real world exposure to pathogens, however, is a sequence of discrete events where concurrent or prior pathogen arrival affects the capacity of immune effectors to engage and kill newly arriving pathogens. We model immune effector and pathogen interactions during the period before infection becomes established in order to capture the dynamics generating dose timing effects. Model analysis reveals an inverse relationship between the time over which exposures accumulate and the risk of infection. Data from one time dose experiments will thus overestimate per pathogen infection risks of real world exposures. For instance, fitting our model to one time dosing data reveals a risk of 0.66 from 313 Cryptosporidium parvum pathogens. When the temporal exposure window is increased 100-fold using the same parameters fitted by our model to the one time dose data, the risk of infection is reduced to 0.09. Confirmation of this risk prediction requires data from experiments administering doses with different timings. Our model demonstrates that dose timing could markedly alter the risks generated by airborne versus fomite transmitted pathogens. PMID:19503605

Evolution of acuteness in pathogen metapopulations: conflicts between “classical” and invasion-persistence trade-offs

PubMed Central

Shrestha, Sourya; Bjørnstad, Ottar N.; King, Aaron A.

2014-01-01

Classical life-history theory predicts that acute, immunizing pathogens should maximize between-host transmission. When such pathogens induce violent epidemic outbreaks, however, a pathogen’s short-term advantage at invasion may come at the expense of its ability to persist in the population over the long term. Here, we seek to understand how the classical and invasion-persistence trade-offs interact to shape pathogen life-history evolution as a function of the size and structure of the host population. We develop an individual-based infection model at three distinct levels of organization: within an individual host, among hosts within a local population, and among local populations within a metapopulation. We find a continuum of evolutionarily stable pathogen strategies. At one end of the spectrum—in large well-mixed populations—pathogens evolve to greater acuteness to maximize between-host transmission: the classical trade-off theory applies in this regime. At the other end of the spectrum—when the host population is broken into many small patches—selection favors less acute pathogens, which persist longer within a patch and thereby achieve enhanced between-patch transmission: the invasion-persistence tradeoff dominates in this regime. Between these extremes, we explore the effects of the size and structure of the host population in determining pathogen strategy. In general, pathogen strategies respond to evolutionary pressures arising at both scales. PMID:25214895

SAM Pathogen Methods Query

EPA Pesticide Factsheets

Laboratories measuring target pathogen analytes in environmental samples can use this online query tool to identify analytical methods in EPA's Selected Analytical Methods for Environmental Remediation and Recovery for select pathogens.

Lack of host specialization on winter annual grasses in the fungal seed bank pathogen Pyrenophora semeniperda

Treesearch

Julie Beckstead; Susan E. Meyer; Toby S. Ishizuka; Kelsey M. McEvoy; Craig E. Coleman

2016-01-01

Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora...

Metagenomes of Microbial Communities in Arsenic- and Pathogen-Contaminated Well and Surface Water from Bangladesh

PubMed Central

Layton, Alice C.; Chauhan, Archana; Williams, Daniel E.; Mailloux, Brian; Knappett, Peter S. K.; Ferguson, Andrew S.; McKay, Larry D.; Alam, M. Jahangir; Matin Ahmed, Kazi; van Geen, Alexander

2014-01-01

The contamination of drinking water from both arsenic and microbial pathogens occurs in Bangladesh. A general metagenomic survey of well water and surface water provided information on the types of pathogens present and may help elucidate arsenic metabolic pathways and potential assay targets for monitoring surface-to-ground water pathogen transport. PMID:25414497

Fusarium algeriense sp. nov., a novel toxigenic crown rot pathogen of durum wheat from Algeria is nested within the Fusarium burgessii species complex

USDA-ARS?s Scientific Manuscript database

A novel crown rot pathogen of wheat discovered during pathogen surveys of Algeria in 2014 and 2015 is formally described here as Fusarium algeriense. Multilocus molecular phylogenetic data resolved the eight isolates of this pathogen as a genealogically exclusive species lineage within the F. burges...

Correlation of isolability of the oak wilt pathogen with leaf wilt and vascular water flow resistance

Treesearch

Garold F. Gregory

1971-01-01

Isolations and water flow-rate measurements made on short stem sections of young red oak seedlings inoculated with the oak wilt pathogen, Ceratocystis fagacearum, about 1 to 2 inches above the soil line, revealed that the oak wilt pathogen was isolable first near the inoculation site. As time after inoculation increased, the pathogen was isolated...

The multigenic nature of the differences in pathogenicity of H5N1 highly pathogenic avian influenza viruses in domestic ducks

USDA-ARS?s Scientific Manuscript database

The Eurasian H5N1 highly pathogenic avian influenza (HPAI) viruses have evolved into many genetic lineages. The divergent strains that have arisen express distinct pathobiological features and increased virulence for many bird species including domestic waterfowl. The pathogenicity of H5N1 HPAI vi...

[Analysis of Pathogenic Bacteria in Reclaimed Water and Impact of UV Disinfection on the Removal of Pathogenic Bacteria].

PubMed

Jing, Ming; Wang, Lei

2016-02-15

In the study, 454-pyrosequencing technology was employed to investigate the species of pathogenic bacteria and the proportion of each pathogen in secondary effluent. Culture-based, qPCR and Q-RT-PCR methods were employed to analyze the removal of indicator (E. coli) and pathogen (Salmonella and Mycobacterium) by ultraviolet (UV) disinfection at a dose of 60 mJ x Cm(-2). The results showed that 11 kinds of pathogenic bacteria were found and the most abundant potentially pathogenic bacteria in the secondary effluent were affiliated with the genera of Clostridium (2.96%), Arcobacter (0.82%) and Mycobacterium (0.36%). 99.9% of culturable E. coli and Salmonella were removed by UV disinfection (60 mJ x cm(-2), however, less than 90% of culturable Mycobacterium were removed. The removal efficiencies of viable E. coli, Salmonella and Mycobacterium were low. Q-RT-PCR seemed to be a promising method for evaluating viable microorganisms in samples. Besides, pathogenic bacteria entered into VBNC state at a UV dose of 60 mJ x cm(-2). Other advanced treatment processes were needed to ensure safe utilization of reclaimed water.

Limiting damage during infection: lessons from infection tolerance for novel therapeutics.

PubMed

Vale, Pedro F; Fenton, Andy; Brown, Sam P

2014-01-01

The distinction between pathogen elimination and damage limitation during infection is beginning to change perspectives on infectious disease control, and has recently led to the development of novel therapies that focus on reducing the illness caused by pathogens (‘‘damage limitation’’)rather than reducing pathogen burdens directly (‘‘pathogen elimination’’). While beneficial at the individual host level, the population consequences of these interventions remain unclear. To address this issue,we present a simple conceptual framework for damage limitation during infection that distinguishes between therapies that are either host-centric (pro-tolerance) or pathogen-centric (anti-virulence). We then draw on recent developments from the evolutionary ecology of disease tolerance to highlight some potential epidemiological and evolutionary responses of pathogens to medical interventions that target the symptoms of infection. Just as pathogens are known to evolve in response to antimicrobial and vaccination therapies, we caution that claims of ‘‘evolution-proof’’ anti-virulence interventions may be premature, and further, that in infections where virulence and transmission are linked, reducing illness without reducing pathogen burden could have non-trivial epidemiological and evolutionary consequences that require careful examination.

Waterborne Pathogens: Detection Methods and Challenges

PubMed Central

Ramírez-Castillo, Flor Yazmín; Loera-Muro, Abraham; Jacques, Mario; Garneau, Philippe; Avelar-González, Francisco Javier; Harel, Josée; Guerrero-Barrera, Alma Lilián

2015-01-01

Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems’ infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health. PMID:26011827

Lipids in host-pathogen interactions: pathogens exploit the complexity of the host cell lipidome.

PubMed

van der Meer-Janssen, Ynske P M; van Galen, Josse; Batenburg, Joseph J; Helms, J Bernd

2010-01-01

Lipids were long believed to have a structural role in biomembranes and a role in energy storage utilizing cellular lipid droplets and plasma lipoproteins. Research over the last decades has identified an additional role of lipids in cellular signaling, membrane microdomain organization and dynamics, and membrane trafficking. These properties make lipids an attractive target for pathogens to modulate host cell processes in order to allow their survival and replication. In this review we will summarize the often ingenious strategies of pathogens to modify the lipid homeostasis of host cells, allowing them to divert cellular processes. To this end pathogens take full advantage of the complexity of the lipidome. The examples are categorized in generalized and emerging principles describing the involvement of lipids in host-pathogen interactions. Several pathogens are described that simultaneously induce multiple changes in the host cell signaling and trafficking mechanisms. Elucidation of these pathogen-induced changes may have important implications for drug development. The emergence of high-throughput lipidomic techniques will allow the description of changes of the host cell lipidome at the level of individual molecular lipid species and the identification of lipid biomarkers.

Airborne pathogens from dairy manure aerial irrigation and the human health risk

USGS Publications Warehouse

Borchardt, Mark A.; Burch, Tucker R

2016-01-01

Dairy manure, like the fecal excrement from any domesticated or wild animal, can contain pathogens capable of infecting humans and causing illness or even death. Pathogens in dairy manure can be broadly divided into categories of taxonomy or infectiousness. Dividing by taxonomy there are three pathogen groups in dairy manure: viruses (e.g., bovine rotavirus), bacteria (e.g., Salmonella species), and protozoa (e.g., Cryptosporidium parvum). There are two categories of infectiousness for pathogens found in animals: those that are zoonotic and those that are not. A zoonotic pathogen is one that can infect both human and animal hosts. Some zoonotic pathogens found in dairy manure cause illness in both hosts (e.g., Salmonella) while other zoonotic pathogens, like Escherichia coli O157:H7, (enterohemorrhagic E. coli (EHEC)) cause illness only in humans. As a general rule, the gastrointestinal viruses found in dairy manure are not zoonotic. While there are exceptions (e.g., rare reports of bovine rotavirus infecting children), for the most part the viruses in dairy manure are not a human health concern. The primary concerns are the zoonotic bacteria and protozoa in dairy manure.

Keeping Control: The Role of Senescence and Development in Plant Pathogenesis and Defense

PubMed Central

Häffner, Eva; Konietzki, Sandra; Diederichsen, Elke

2015-01-01

Many plant pathogens show interactions with host development. Pathogens may modify plant development according to their nutritional demands. Conversely, plant development influences pathogen growth. Biotrophic pathogens often delay senescence to keep host cells alive, and resistance is achieved by senescence-like processes in the host. Necrotrophic pathogens promote senescence in the host, and preventing early senescence is a resistance strategy of plants. For hemibiotrophic pathogens both patterns may apply. Most signaling pathways are involved in both developmental and defense reactions. Increasing knowledge about the molecular components allows to distinguish signaling branches, cross-talk and regulatory nodes that may influence the outcome of an infection. In this review, recent reports on major molecular players and their role in senescence and in pathogen response are reviewed. Examples of pathosystems with strong developmental implications illustrate the molecular basis of selected control strategies. A study of gene expression in the interaction between the hemibiotrophic vascular pathogen Verticillium longisporum and its cruciferous hosts shows processes that are fine-tuned to counteract early senescence and to achieve resistance. The complexity of the processes involved reflects the complex genetic control of quantitative disease resistance, and understanding the relationship between disease, development and resistance will support resistance breeding. PMID:27135337

Trans-Kingdom RNA Silencing in Plant-Fungal Pathogen Interactions.

PubMed

Hua, Chenlei; Zhao, Jian-Hua; Guo, Hui-Shan

2018-02-05

Fungal pathogens represent a major group of plant invaders that are the causative agents of many notorious plant diseases. Large quantities of RNAs, especially small RNAs involved in gene silencing, have been found to transmit bidirectionally between fungal pathogens and their hosts. Although host-induced gene silencing (HIGS) technology has been developed and applied to protect crops from fungal infections, the mechanisms of RNA transmission, especially small RNAs regulating trans-kingdom RNA silencing in plant immunity, are largely unknown. In this review, we summarize and discuss recent important findings regarding trans-kingdom sRNAs and RNA silencing in plant-fungal pathogen interactions compared with the well-known RNAi mechanisms in plants and fungi. We focus on the interactions between plant and fungal pathogens with broad hosts, represented by the vascular pathogen Verticillium dahliae and non-vascular pathogen Botrytis cinerea, and discuss the known instances of natural RNAi transmission between fungal pathogens and host plants. Given that HIGS has been developed and recently applied in controlling Verticillium wilt diseases, we propose an ideal research system exploiting plant vasculature-Verticillium interaction to further study trans-kingdom RNA silencing. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

The Comprehensive Phytopathogen Genomics Resource: a web-based resource for data-mining plant pathogen genomes.

PubMed

Hamilton, John P; Neeno-Eckwall, Eric C; Adhikari, Bishwo N; Perna, Nicole T; Tisserat, Ned; Leach, Jan E; Lévesque, C André; Buell, C Robin

2011-01-01

The Comprehensive Phytopathogen Genomics Resource (CPGR) provides a web-based portal for plant pathologists and diagnosticians to view the genome and trancriptome sequence status of 806 bacterial, fungal, oomycete, nematode, viral and viroid plant pathogens. Tools are available to search and analyze annotated genome sequences of 74 bacterial, fungal and oomycete pathogens. Oomycete and fungal genomes are obtained directly from GenBank, whereas bacterial genome sequences are downloaded from the A Systematic Annotation Package (ASAP) database that provides curation of genomes using comparative approaches. Curated lists of bacterial genes relevant to pathogenicity and avirulence are also provided. The Plant Pathogen Transcript Assemblies Database provides annotated assemblies of the transcribed regions of 82 eukaryotic genomes from publicly available single pass Expressed Sequence Tags. Data-mining tools are provided along with tools to create candidate diagnostic markers, an emerging use for genomic sequence data in plant pathology. The Plant Pathogen Ribosomal DNA (rDNA) database is a resource for pathogens that lack genome or transcriptome data sets and contains 131 755 rDNA sequences from GenBank for 17 613 species identified as plant pathogens and related genera. Database URL: http://cpgr.plantbiology.msu.edu.

Transient virulence of emerging pathogens.

PubMed

Bolker, Benjamin M; Nanda, Arjun; Shah, Dharmini

2010-05-06

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

Transient virulence of emerging pathogens

PubMed Central

Bolker, Benjamin M.; Nanda, Arjun; Shah, Dharmini

2010-01-01

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution. PMID:19864267

Experimental evidence of a pathogen invasion threshold

PubMed Central

Krkošek, Martin

2018-01-01

Host density thresholds to pathogen invasion separate regions of parameter space corresponding to endemic and disease-free states. The host density threshold is a central concept in theoretical epidemiology and a common target of human and wildlife disease control programmes, but there is mixed evidence supporting the existence of thresholds, especially in wildlife populations or for pathogens with complex transmission modes (e.g. environmental transmission). Here, we demonstrate the existence of a host density threshold for an environmentally transmitted pathogen by combining an epidemiological model with a microcosm experiment. Experimental epidemics consisted of replicate populations of naive crustacean zooplankton (Daphnia dentifera) hosts across a range of host densities (20–640 hosts l−1) that were exposed to an environmentally transmitted fungal pathogen (Metschnikowia bicuspidata). Epidemiological model simulations, parametrized independently of the experiment, qualitatively predicted experimental pathogen invasion thresholds. Variability in parameter estimates did not strongly influence outcomes, though systematic changes to key parameters have the potential to shift pathogen invasion thresholds. In summary, we provide one of the first clear experimental demonstrations of pathogen invasion thresholds in a replicated experimental system, and provide evidence that such thresholds may be predictable using independently constructed epidemiological models. PMID:29410876

Dancing with the Stars: How Choreographed Bacterial Interactions Dictate Nososymbiocity and Give Rise to Keystone Pathogens, Accessory Pathogens, and Pathobionts.

PubMed

Hajishengallis, George; Lamont, Richard J

2016-06-01

Many diseases that originate on mucosal membranes ensue from the action of polymicrobial communities of indigenous organisms working in concert to disrupt homeostatic mechanisms. Multilevel physical and chemical communication systems among constituent organisms underlie polymicrobial synergy and dictate the community's pathogenic potential or nososymbiocity, that is, disease arising from living together with a susceptible host. Functional specialization of community participants, often originating from metabolic codependence, has given rise to several newly appreciated designations within the commensal-to-pathogen spectrum. Accessory pathogens, while inherently commensal in a particular microenvironment, nonetheless enhance the colonization or metabolic activity of pathogens. Keystone pathogens (bacterial drivers or alpha-bugs) exert their influence at low abundance by modulating both the composition and levels of community participants and by manipulating host responses. Pathobionts (or bacterial passengers) exploit disrupted host homeostasis to flourish and promote inflammatory disease. In this review we discuss how commensal or pathogenic properties of organisms are not intrinsic features, and have to be considered within the context of both the microbial community in which they reside and the host immune status. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification and characterization of novel natural pathogen of Drosophila melanogaster isolated from wild captured Drosophila spp.

PubMed

Singh, Karan; Zulkifli, Mohammad; Prasad, N G

2016-12-01

Drosophila melanogaster is an emerging model system for the study of evolutionary ecology of immunity. However, a large number of studies have used non natural pathogens as very few natural pathogens have been isolated and identified. Our aim was to isolate and characterize natural pathogen/s of D. melanogaster. A bacterial pathogen was isolated from wild caught Drosophila spp., identified as a new strain of Staphylococcus succinus subsp. succinus and named PK-1. This strain induced substantial mortality (36-62%) in adults of several laboratory populations of D. melanogaster. PK-1 grew rapidly within the body of the flies post infection and both males and females had roughly same number of colony forming units. Mortality was affected by mode of infection and dosage of the pathogen. However mating status of the host had no effect on mortality post infection. Given that there are very few known natural bacterial pathogens of D. melanogaster and that PK-1 can establish a sustained infection across various outbred and inbred populations of D. melanogaster this new isolate is a potential resource for future studies on immunity. Copyright © 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Application of low frequency pulsed ohmic heating for inactivation of foodborne pathogens and MS-2 phage in buffered peptone water and tomato juice.

PubMed

Kim, Sang-Soon; Choi, Won; Kang, Dong-Hyun

2017-05-01

The purpose of this study was to inactivate foodborne pathogens effectively by ohmic heating in buffered peptone water and tomato juice without causing electrode corrosion and quality degradation. Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes were used as representative foodborne pathogens and MS-2 phage was used as a norovirus surrogate. Buffered peptone water and tomato juice inoculated with pathogens were treated with pulsed ohmic heating at different frequencies (0.06-1 kHz). Propidium iodide uptake values of bacterial pathogens were significantly (p < 0.05) larger at 0.06-0.5 kHz than at 1 kHz, and sub-lethal injury of pathogenic bacteria was reduced by decreasing frequency. MS-2 phage was inactivated more effectively at low frequency, and was more sensitive to acidic conditions than pathogenic bacteria. Electrode corrosion and quality degradation of tomato juice were not observed regardless of frequency. This study suggests that low frequency pulsed ohmic heating is applicable to inactivate foodborne pathogens effectively without causing electrode corrosion and quality degradation in tomato juice. Copyright © 2016. Published by Elsevier Ltd.

A potentially fatal mix of herpes in zoos.

PubMed

Greenwood, Alex D; Tsangaras, Kyriakos; Ho, Simon Y W; Szentiks, Claudia A; Nikolin, Veljko M; Ma, Guanggang; Damiani, Armando; East, Marion L; Lawrenz, Arne; Hofer, Heribert; Osterrieder, Nikolaus

2012-09-25

Pathogens often have a limited host range, but some can opportunistically jump to new species. Anthropogenic activities that mix reservoir species with novel, hence susceptible, species can provide opportunities for pathogens to spread beyond their normal host range. Furthermore, rapid evolution can produce new pathogens by mechanisms such as genetic recombination. Zoos unintentionally provide pathogens with a high diversity of species from different continents and habitats assembled within a confined space. Institutions alert to the problem of pathogen spread to unexpected hosts can monitor the emergence of pathogens and take preventative measures. However, asymptomatic infections can result in the causative pathogens remaining undetected in their reservoir host. Furthermore, pathogen spread to unexpected hosts may remain undiagnosed if the outcome of infection is limited, as in the case of compromised fertility, or if more severe outcomes are restricted to less charismatic species that prompt only limited investigation. We illustrate this problem here with a recombinant zebra herpesvirus infecting charismatic species including zoo polar bears over at least four years. The virus may cause fatal encephalitis and infects at least five mammalian orders, apparently without requiring direct contact with infected animals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Molecular phylogeny, pathogenicity and toxigenicity of Fusarium oxysporum f. sp. lycopersici

PubMed Central

Nirmaladevi, D.; Venkataramana, M.; Srivastava, Rakesh K.; Uppalapati, S. R.; Gupta, Vijai Kumar; Yli-Mattila, T.; Clement Tsui, K. M.; Srinivas, C.; Niranjana, S. R.; Chandra, Nayaka S.

2016-01-01

The present study aimed at the molecular characterization of pathogenic and non pathogenic F. oxysporum f. sp. lycopersici strains isolated from tomato. The causal agent isolated from symptomatic plants and soil samples was identified based on morphological and molecular analyses. Pathogenicity testing of 69 strains on five susceptible tomato varieties showed 45% of the strains were highly virulent and 30% were moderately virulent. Molecular analysis based on the fingerprints obtained through ISSR indicated the presence of wide genetic diversity among the strains. Phylogenetic analysis based on ITS sequences showed the presence of at least four evolutionary lineages of the pathogen. The clustering of F. oxysporum with non pathogenic isolates and with the members of other formae speciales indicated polyphyletic origin of F. oxysporum f. sp. lycopersici. Further analysis revealed intraspecies variability and nucleotide insertions or deletions in the ITS region among the strains in the study and the observed variations were found to be clade specific. The high genetic diversity in the pathogen population demands for development of effective resistance breeding programs in tomato. Among the pathogenic strains tested, toxigenic strains harbored the Fum1 gene clearly indicating that the strains infecting tomato crops have the potential to produce Fumonisin. PMID:26883288

Genome-Wide Analysis in Three Fusarium Pathogens Identifies Rapidly Evolving Chromosomes and Genes Associated with Pathogenicity

PubMed Central

Sperschneider, Jana; Gardiner, Donald M.; Thatcher, Louise F.; Lyons, Rebecca; Singh, Karam B.; Manners, John M.; Taylor, Jennifer M.

2015-01-01

Pathogens and hosts are in an ongoing arms race and genes involved in host–pathogen interactions are likely to undergo diversifying selection. Fusarium plant pathogens have evolved diverse infection strategies, but how they interact with their hosts in the biotrophic infection stage remains puzzling. To address this, we analyzed the genomes of three Fusarium plant pathogens for genes that are under diversifying selection. We found a two-speed genome structure both on the chromosome and gene group level. Diversifying selection acts strongly on the dispensable chromosomes in Fusarium oxysporum f. sp. lycopersici and on distinct core chromosome regions in Fusarium graminearum, all of which have associations with virulence. Members of two gene groups evolve rapidly, namely those that encode proteins with an N-terminal [SG]-P-C-[KR]-P sequence motif and proteins that are conserved predominantly in pathogens. Specifically, 29 F. graminearum genes are rapidly evolving, in planta induced and encode secreted proteins, strongly pointing toward effector function. In summary, diversifying selection in Fusarium is strongly reflected as genomic footprints and can be used to predict a small gene set likely to be involved in host–pathogen interactions for experimental verification. PMID:25994930

Study of Staphylococcus aureus N315 Pathogenic Genes by Text Mining and Enrichment Analysis of Pathways and Operons.

PubMed

Yang, Chun-Feng; Gou, Wei-Hui; Dai, Xin-Lun; Li, Yu-Mei

2018-06-01

Staphylococcus aureus (S. aureus) is a versatile pathogen found in many environments and can cause nosocomial infections in the community and hospitals. S. aureus infection is an increasingly serious threat to global public health that requires action across many government bodies, medical and health sectors, and scientific research institutions. In the present study, S. aureus N315 genes that have been shown in the literature to be pathogenic were extracted using a bibliometric method for functional enrichment analysis of pathways and operons to statistically discover novel pathogenic genes associated with S. aureus N315. A total of 383 pathogenic genes were mined from the literature using bibliometrics, and subsequently a few new pathogenic genes of S. aureus N315 were identified by functional enrichment analysis of pathways and operons. The discovery of these novel S. aureus N315 pathogenic genes is of great significance to treat S. aureus induced diseases and identify potential diagnostic markers, thus providing theoretical fundamentals for epidemiological prevention.

Label and label-free based surface-enhanced Raman scattering for pathogen bacteria detection: A review.

PubMed

Liu, Yu; Zhou, Haibo; Hu, Ziwei; Yu, Guangxia; Yang, Danting; Zhao, Jinshun

2017-08-15

Rapid, accurate detection of pathogen bacteria is a highly topical research area for the sake of food safety and public health. Surface-enhanced Raman scattering (SERS) is being considered as a powerful and attractive technique for pathogen bacteria detection, due to its sensitivity, high speed, comparatively low cost, multiplexing ability and portability. This contribution aims to give a comprehensive overview of SERS as a technique for rapid detection of pathogen bacteria based on label and label-free strategies. A brief tutorial on SERS is given first of all. Then we summarize the recent trends and developments of label and label-free based SERS applied to detection of pathogen bacteria, including the relatively complete interpretation of SERS spectra. In addition, multifunctional SERS platforms for pathogen bacteria in matrix are discussed as well. Furthermore, an outlook of the work done and a perspective on the future directions of SERS as a reliable tool for real-time pathogen bacteria detection are given. Copyright © 2017 Elsevier B.V. All rights reserved.

A method to quantify infectious airborne pathogens at concentrations below the threshold of quantification by culture

PubMed Central

Cutler, Timothy D.; Wang, Chong; Hoff, Steven J.; Zimmerman, Jeffrey J.

2013-01-01

In aerobiology, dose-response studies are used to estimate the risk of infection to a susceptible host presented by exposure to a specific dose of an airborne pathogen. In the research setting, host- and pathogen-specific factors that affect the dose-response continuum can be accounted for by experimental design, but the requirement to precisely determine the dose of infectious pathogen to which the host was exposed is often challenging. By definition, quantification of viable airborne pathogens is based on the culture of micro-organisms, but some airborne pathogens are transmissible at concentrations below the threshold of quantification by culture. In this paper we present an approach to the calculation of exposure dose at microbiologically unquantifiable levels using an application of the “continuous-stirred tank reactor (CSTR) model” and the validation of this approach using rhodamine B dye as a surrogate for aerosolized microbial pathogens in a dynamic aerosol toroid (DAT). PMID:24082399

Diversity and role of cave-dwelling hematophagous insects in pathogen transmission in the Afrotropical region.

PubMed

Obame-Nkoghe, Judicaël; Leroy, Eric-Maurice; Paupy, Christophe

2017-04-12

The progressive anthropization of caves for food resources or economic purposes increases human exposure to pathogens that naturally infect cave-dwelling animals. The presence of wild or domestic animals in the immediate surroundings of caves also may contribute to increasing the risk of emergence of such pathogens. Some zoonotic pathogens are transmitted through direct contact, but many others require arthropod vectors, such as blood-feeding insects. In Africa, hematophagous insects often play a key role in the epidemiology of many pathogens; however, their ecology in cave habitats remains poorly known. During the last decades, several investigations carried out in Afrotropical caves suggested the medical and veterinary importance particularly of insect taxa of the Diptera order. Therefore, the role of some of these insects as vectors of pathogens that infect cave-dwelling vertebrates has been studied. The present review summarizes these findings, brings insights into the diversity of cave-dwelling hematophagous Diptera and their involvement in pathogen transmission, and finally discusses new challenges and future research directions.

Pathogenic simian immunodeficiency virus infection is associated with expansion of the enteric virome

PubMed Central

Handley, Scott; Thackray, Larissa B.; Zhao, Guoyan; Presti, Rachel; Miller, Andrew; Droit, Lindsay; Abbink, Peter; Maxfield, Lori F.; Kambal, Amal; Duan, Erning; Stanley, Kelly; Kramer, Joshua; Macri, Sheila C.; Permar, Sallie R.; Schmitz, Joern E.; Mansfield, Keith; Brenchley, Jason M.; Veazey, Ronald S.; Stappenbeck, Thaddeus S.; Wang, David; Barouch, Dan H.; Virgin, Herbert W.

2012-01-01

SUMMARY Pathogenic simian immunodeficiency virus (SIV) infection is associated with enteropathy which likely contributes to AIDS progression. To identify candidate etiologies for AIDS enteropathy, we used next generation sequencing to define the enteric virome during SIV infection in nonhuman primates. Pathogenic, but not non-pathogenic, SIV infection was associated with significant expansion of the enteric virome. We identified at least 32 previously undescribed enteric viruses during pathogenic SIV infection and confirmed their presence using viral culture and PCR testing. We detected unsuspected mucosal adenovirus infection associated with enteritis as well as parvovirus viremia in animals with advanced AIDS, indicating the pathogenic potential of SIV-associated expansion of the enteric virome. No association between pathogenic SIV infection and the family-level taxonomy of enteric bacteria was detected. Thus, enteric viral infections may contribute to AIDS enteropathy and disease progression. These findings underline the importance of metagenomic analysis of the virome for understanding AIDS pathogenesis. PMID:23063120

Effectiveness of traveller screening for emerging pathogens is shaped by epidemiology and natural history of infection

PubMed Central

Gostic, Katelyn M; Kucharski, Adam J; Lloyd-Smith, James O

2015-01-01

During outbreaks of high-consequence pathogens, airport screening programs have been deployed to curtail geographic spread of infection. The effectiveness of screening depends on several factors, including pathogen natural history and epidemiology, human behavior, and characteristics of the source epidemic. We developed a mathematical model to understand how these factors combine to influence screening outcomes. We analyzed screening programs for six emerging pathogens in the early and late stages of an epidemic. We show that the effectiveness of different screening tools depends strongly on pathogen natural history and epidemiological features, as well as human factors in implementation and compliance. For pathogens with longer incubation periods, exposure risk detection dominates in growing epidemics, while fever becomes a better target in stable or declining epidemics. For pathogens with short incubation, fever screening drives detection in any epidemic stage. However, even in the most optimistic scenario arrival screening will miss the majority of cases. DOI: http://dx.doi.org/10.7554/eLife.05564.001 PMID:25695520

Toward a better guard of coastal water safety-Microbial distribution in coastal water and their facile detection.

PubMed

Xie, Yunxuan; Qiu, Ning; Wang, Guangyi

2017-05-15

Prosperous development in marine-based tourism has raised increasing concerns over the sanitary quality of coastal waters with potential microbial contamination. The World Health Organization has set stringent standards over a list of pathogenic microorganisms posing potential threats to people with frequent coastal water exposure and has asked for efficient detection procedures for pathogen facile identification. Inspection of survey events regarding the occurrence of marine pathogens in recreational beaches in recent years has reinforced the need for the development of a rapid identification procedure. In this review, we examine the possibility of recruiting uniform molecular assays to identify different marine pathogens and the feasibility of appropriate biomarkers, including enterochelin biosynthetic genes, for general toxicity assays. The focus is not only on bacterial pathogens but also on other groups of infectious pathogens. The ultimate goal is the development of a handy method to more efficiently and rapidly detect marine pathogens. Copyright © 2017 Elsevier Ltd. All rights reserved.

Convergent targeting of a common host protein-network by pathogen effectors from three kingdoms of life

PubMed Central

Weßling, Ralf; Epple, Petra; Altmann, Stefan; He, Yijian; Yang, Li; Henz, Stefan R.; McDonald, Nathan; Wiley, Kristin; Bader, Kai Christian; Gläßer, Christine; Mukhtar, M. Shahid; Haigis, Sabine; Ghamsari, Lila; Stephens, Amber E.; Ecker, Joseph R.; Vidal, Marc; Jones, Jonathan D. G.; Mayer, Klaus F. X.; van Themaat, Emiel Ver Loren; Weigel, Detlef; Schulze-Lefert, Paul; Dangl, Jeffery L.; Panstruga, Ralph; Braun, Pascal

2014-01-01

SUMMARY While conceptual principles governing plant immunity are becoming clear, its systems-level organization and the evolutionary dynamic of the host-pathogen interface are still obscure. We generated a systematic protein-protein interaction network of virulence effectors from the ascomycete pathogen Golovinomyces orontii and Arabidopsis thaliana host proteins. We combined this dataset with corresponding data for the eubacterial pathogen Pseudomonas syringae and the oomycete pathogen Hyaloperonospora arabidopsidis. The resulting network identifies host proteins onto which intraspecies and interspecies pathogen effectors converge. Phenotyping of 124 Arabidopsis effector-interactor mutants revealed a correlation between intra- and interspecies convergence and several altered immune response phenotypes. The effectors and most heavily targeted host protein co-localized in sub-nuclear foci. Products of adaptively selected Arabidopsis genes are enriched for interactions with effector targets. Our data suggest the existence of a molecular host-pathogen interface that is conserved across Arabidopsis accessions, while evolutionary adaptation occurs in the immediate network neighborhood of effector targets. PMID:25211078

Host-pathogen interaction in Fusarium oxysporum infections: where do we stand?

PubMed

Husaini, Amjad M; Sakina, Aafreen; Cambay, Souliha R

2018-03-16

Fusarium oxysporum, a ubiquitous soil-borne pathogen causes devastating vascular wilt in more than 100 plant species and ranks fifth among top ten fungal plant pathogens. It has emerged as a human pathogen too, causing infections in immune-compromised patients. It is, therefore, important to gain insight into the molecular processes involved in the pathogenesis of this trans-kingdom pathogen. A complex network comprising of interconnected and over lapping signal pathways; mitogen-activated protein kinase (MAPK) signaling pathways, Ras proteins, G-protein signaling components and their downstream pathways, components of the velvet (LaeA/VeA/VelB) complex and cAMP pathways, is involved in perceiving the host. This network regulates the expression of various pathogenicity genes. Plants have however evolved an elaborate protection system to combat this attack. They too possess intricate mechanisms at molecular level, which once triggered by pathogen attack transduce signals to activate defense response. This review focuses on understanding and presenting a wholistic picture of the molecular mechanisms of F. oxysporum-host interactions in plant immunity.

Opportunistic respiratory pathogens in the oral cavity of the elderly.

PubMed

Tada, Akio; Hanada, Nobuhiro

2010-10-01

The oral cavity of the hospitalized or bedridden elderly is often a reservoir for opportunistic pathogens associated with respiratory diseases. Commensal flora and the host interact in a balanced fashion and oral infections are considered to appear following an imbalance in the oral resident microbiota, leading to the emergence of potentially pathogenic bacteria. The definition of the process involved in colonization by opportunistic respiratory pathogens needs to elucidate the factors responsible for the transition of the microbiota from commensal to pathogenic flora. The regulatory factors influencing the oral ecosystem can be divided into three major categories: the host defense system, commensal bacteria, and external pathogens. In this article, we review the profile of these categories including the intricate cellular interaction between immune factors and commensal bacteria and the disturbance in homeostasis in the oral cavity of hospitalized or bedridden elderly, which facilitates oral colonization by opportunistic respiratory pathogens. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Presence of pathogenic amoebae in power plant cooling waters. Final report, October 15, 1977-September 30, 1979. [Naegleria fowleri

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

Tyndall, R.L.; Willaert, E.; Stevens, A.R.

1981-03-01

Cooling-water-associated algae and sediments from five northern and five southern or western electric power plants were tested for the presence of pathogenic amoebae. In addition, water algae and sediments from five northern and five southern/western sites not associated with power plants were tested. There was a significant correlation at northern power plants between the presence of thermophilic, pathogenic amoebae in cooling waters and thermal additions. Presence of the pathogenic did not correlate with salinity, pH, conductivity, or a variety of various chemical components of the cooling waters. Selected pathogenic isolates were tested serologically and were classified as Naegleria fowleri. Althoughmore » thermal additions were shown to be contributing factor in predisposing cooling waters to the growth of pathogenic amoebae, the data suggest the involvement of other currently undefined parameters associated with the presence of the pathogenic amoebae. 35 refs., 21 tabs.« less

Detecting Staphylococcus aureus in milk from dairy cows using sniffer dogs.

PubMed

Fischer-Tenhagen, C; Theby, V; Krömker, V; Heuwieser, W

2018-05-01

Fast and accurate identification of disease-causing pathogens is essential for specific antimicrobial therapy in human and veterinary medicine. In these experiments, dogs were trained to identify Staphylococcus aureus and differentiate it from other common mastitis-causing pathogens by smell. Headspaces from agar plates, inoculated raw milk samples, or field samples collected from cows with Staphylococcus aureus and other mastitis-causing pathogens were used for training and testing. The ability to learn the specific odor of Staphylococcus aureus in milk depended on the concentration of the pathogens in the training samples. Sensitivity and specificity for identifying Staphylococcus aureus were 91.3 and 97.9%, respectively, for pathogens grown on agar plates; 83.8 and 98.0% for pathogens inoculated in raw milk; and 59.0 and 93.2% for milk samples from mastitic cows. The results of these experiments underline the potential of odor detection as a diagnostic tool for pathogen diagnosis. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Growth and survival of foodborne pathogens in beer.

PubMed

Menz, Garry; Aldred, Peter; Vriesekoop, Frank

2011-10-01

This work aimed to assess the growth and survival of four foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus) in beer. The effects of ethanol, pH, and storage temperature were investigated for the gram-negative pathogens (E. coli O157:H7 and Salmonella Typhimurium), whereas the presence of hops ensured that the gram-positive pathogens (L. monocytogenes and S. aureus) were rapidly inactivated in alcohol-free beer. The pathogens E. coli O157:H7 and Salmonella Typhimurium could not grow in the mid-strength or full-strength beers, although they could survive for more than 30 days in the mid-strength beer when held at 4°C. These pathogens grew rapidly in the alcohol-free beer; however, growth was prevented when the pH of the alcohol-free beer was lowered from the "as received" value of 4.3 to 4.0. Pathogen survival in all beers was prolonged at lowered storage temperatures.

Controlling hormone signaling is a plant and pathogen challenge for growth and survival.

PubMed

López, Miguel Angel; Bannenberg, Gerard; Castresana, Carmen

2008-08-01

Plants and pathogens have continuously confronted each other during evolution in a battle for growth and survival. New advances in the field have provided fascinating insights into the mechanisms that have co-evolved to gain a competitive advantage in this battle. When plants encounter an invading pathogen, not only responses signaled by defense hormones are activated to restrict pathogen invasion, but also the modulation of additional hormone pathways is required to serve other purposes, which are equally important for plant survival, such as re-allocation of resources, control of cell death, regulation of water stress, and modification of plant architecture. Notably, pathogens can counteract both types of responses as a strategy to enhance virulence. Pathogens regulate production and signaling responses of plant hormones during infection, and also produce phytohormones themselves to modulate plant responses. These results indicate that hormone signaling is a relevant component in plant-pathogen interactions, and that the ability to dictate hormonal directionality is critical to the outcome of an interaction.

Convergent evolution and mimicry of protein linear motifs in host-pathogen interactions.

PubMed

Chemes, Lucía Beatriz; de Prat-Gay, Gonzalo; Sánchez, Ignacio Enrique

2015-06-01

Pathogen linear motif mimics are highly evolvable elements that facilitate rewiring of host protein interaction networks. Host linear motifs and pathogen mimics differ in sequence, leading to thermodynamic and structural differences in the resulting protein-protein interactions. Moreover, the functional output of a mimic depends on the motif and domain repertoire of the pathogen protein. Regulatory evolution mediated by linear motifs can be understood by measuring evolutionary rates, quantifying positive and negative selection and performing phylogenetic reconstructions of linear motif natural history. Convergent evolution of linear motif mimics is widespread among unrelated proteins from viral, prokaryotic and eukaryotic pathogens and can also take place within individual protein phylogenies. Statistics, biochemistry and laboratory models of infection link pathogen linear motifs to phenotypic traits such as tropism, virulence and oncogenicity. In vitro evolution experiments and analysis of natural sequences suggest that changes in linear motif composition underlie pathogen adaptation to a changing environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Homology analysis and cross-immunogenicity of OmpA from pathogenic Yersinia enterocolitica, Yersinia pseudotuberculosis and Yersinia pestis.

PubMed

Chen, Yuhuang; Duan, Ran; Li, Xu; Li, Kewei; Liang, Junrong; Liu, Chang; Qiu, Haiyan; Xiao, Yuchun; Jing, Huaiqi; Wang, Xin

2015-12-01

The outer membrane protein A (OmpA) is one of the intra-species conserved proteins with immunogenicity widely found in the family of Enterobacteriaceae. Here we first confirmed OmpA is conserved in the three pathogenic Yersinia: Yersinia pestis, Yersinia pseudotuberculosis and pathogenic Yersinia enterocolitica, with high homology at the nucleotide level and at the amino acid sequence level. The identity of ompA sequences for 262 Y. pestis strains, 134 Y. pseudotuberculosis strains and 219 pathogenic Y. enterocolitica strains are 100%, 98.8% and 97.7% similar. The main pattern of OmpA of pathogenic Yersinia are 86.2% and 88.8% identical at the nucleotide and amino acid sequence levels, respectively. Immunological analysis showed the immunogenicity of each OmpA and cross-immunogenicity of OmpA for pathogenic Yersinia where OmpA may be a vaccine candidate for Y. pestis and other pathogenic Yersinia. Copyright © 2015 Elsevier Ltd. All rights reserved.

Emerging pathogens in the fish farming industry and sequencing-based pathogen discovery.

PubMed

Tengs, Torstein; Rimstad, Espen

2017-10-01

The use of large scale DNA/RNA sequencing has become an integral part of biomedical research. Reduced sequencing costs and the availability of efficient computational resources has led to a revolution in how problems concerning genomics and transcriptomics are addressed. Sequencing-based pathogen discovery represents one example of how genetic data can now be used in ways that were previously considered infeasible. Emerging pathogens affect both human and animal health due to a multitude of factors, including globalization, a shifting environment and an increasing human population. Fish farming represents a relevant, interesting and challenging system to study emerging pathogens. This review summarizes recent progress in pathogen discovery using sequence data, with particular emphasis on viruses in Atlantic salmon (Salmo salar). Copyright © 2017 Elsevier Ltd. All rights reserved.

Interaction effects of different drivers of wild bee decline and their influence on host-pathogen dynamics.

PubMed

Meeus, Ivan; Pisman, Matti; Smagghe, Guy; Piot, Niels

2018-04-01

Wild bee decline is a multi-factorial problem, yet it is crucial to understand the impact of a single driver. Hereto the interaction effects of wild bee decline with multiple natural and anthropogenic stressors need to be clear. This is also true for the driver 'pathogens', as stressor induced disturbances of natural host-pathogen dynamics can unbalance settled virulence equilibria. Invasive species, bee domestication, habitat loss, climate changes and insecticides are recognized drivers of wild bee decline, but all influence host-pathogen dynamics as well. Many wild bee pathogens have multiple hosts, which relaxes the host-density limitation of virulence evolution. In conclusion, disturbances of bee-pathogen dynamics can be compared to a game of Russian roulette. Copyright © 2018. Published by Elsevier Inc.

Protective Microbiota: From Localized to Long-Reaching Co-Immunity

PubMed Central

Chiu, Lynn; Bazin, Thomas; Truchetet, Marie-Elise; Schaeverbeke, Thierry; Delhaes, Laurence; Pradeu, Thomas

2017-01-01

Resident microbiota do not just shape host immunity, they can also contribute to host protection against pathogens and infectious diseases. Previous reviews of the protective roles of the microbiota have focused exclusively on colonization resistance localized within a microenvironment. This review shows that the protection against pathogens also involves the mitigation of pathogenic impact without eliminating the pathogens (i.e., “disease tolerance”) and the containment of microorganisms to prevent pathogenic spread. Protective microorganisms can have an impact beyond their niche, interfering with the entry, establishment, growth, and spread of pathogenic microorganisms. More fundamentally, we propose a series of conceptual clarifications in support of the idea of a “co-immunity,” where an organism is protected by both its own immune system and components of its microbiota. PMID:29270167

[Rapid identification of meningitis due to bacterial pathogens].

PubMed

Ubukata, Kimiko

2013-01-01

We constructed a new real-time PCR method to detect causative pathogens in cerebrospinal fluid (CSF) from patient due to bacterial meningitis. The eight pathogens targeted in the PCR are Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus agalactiae, Staphylococcus aurues, Neisseria meningitides, Listeria monocytogenes, Esherichia coli, and Mycoplasma pneumoniae. The total time from DNA extraction from CSF to PCR analysis was 1.5 hour. The pathogens were detected in 72% of the CSF samples (n=115) by real-time PCR, but in only 48% by culture, although the microorganisms were completely concordant. The detection rate of pathogens with PCR was significantly better than that with cultures in patients with antibiotic administration.In conclusion, detection with real-time PCR is useful for rapidly identifying the causative pathogens of meningitis and for examining the clinical course of chemotherapy.

Human soil-borne pathogens and risks associated with land use change

NASA Astrophysics Data System (ADS)

Pereg, Lily

2017-04-01

Soil is a source of pathogenic, neutral and beneficial microorganisms. Natural events and anthropogenic activity can affect soil biodiversity and influence the balance and distribution of soil-borne human pathogens. Important bacterial and fungal pathogens, such as Bacillus anthracis, Coxiella bernetii, Clostridium tetani, Escherichia coli 0157:H7, Listeria monocytogenes, Aspergillus fumigatus and Sporothrix schenckii will be discussed. This presentation will concentrate on soil pathogenic microorganisms and the effects of land use change on their prevalence and distribution. In particular, the potential of agricultural soil cultivation to enhance pathogen transmission to human through the release of soil microbes into the air attached to dust particles, contamination of waterways and infection of food plants and animal. Emerging solutions, such as biocontrol and probiotics, will be discussed.

Viral meningitis.

PubMed

Chadwick, David R

2005-01-01

Viruses probably account for most cases of acute meningitis. Viral meningitis is often assumed to be a largely benign disease. For the commonest pathogens causing meningitis, enteroviruses, this is usually the case; however, for many of the other pathogens causing viral meningitis, and for common pathogens in the immunocompromised or infants, viral meningitis is frequently associated with substantial neurological complications and a significant mortality. Diagnostic methods for rapid and accurate identification of pathogens have improved over recent years, permitting more precise and earlier diagnoses. There have been fewer developments in therapies for viral meningitis, and there remain no effective therapies for most pathogens, emphasising the importance of prevention and early diagnosis. This review focuses on the presentation, diagnosis and management of viral meningitis and also covers the prevention of meningitis for pathogens where effective vaccines are available.

Method for detecting pathogens attached to specific antibodies

DOEpatents

Miles, Robin R.; Venkateswaran, Kodumudi S.; Fuller, Christopher K.

2005-01-25

The use of impedance measurements to detect the presence of pathogens attached to antibody-coated beads. In a fluidic device antibodies are immobilized on a surface of a patterned interdigitated electrode. Pathogens in a sample fluid streaming past the electrode attach to the immobilized antibodies, which produces a change in impedance between two adjacent electrodes, which impedance change is measured and used to detect the presence of a pathogen. To amplify the signal, beads coated with antibodies are introduced and the beads would stick to the pathogen causing a greater change in impedance between the two adjacent electrodes.

Impedance measurements for detecting pathogens attached to antibodies

DOEpatents

Miles, Robin R.; Venkateswaran, Kodumudi S.; Fuller, Christopher K.

2004-12-28

The use of impedance measurements to detect the presence of pathogens attached to antibody-coated beads. In a fluidic device antibodies are immobilized on a surface of a patterned interdigitated electrode. Pathogens in a sample fluid streaming past the electrode attach to the immobilized antibodies, which produces a change in impedance between two adjacent electrodes, which impedance change is measured and used to detect the presence of a pathogen. To amplify the signal, beads coated with antibodies are introduced and the beads would stick to the pathogen causing a greater change in impedance between the two adjacent electrodes.

Antimicrobial and anti-inflammatory activity of switchgrass-derived extractives

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

Labbe, Nicole; Ownley, Bonnie H.; Gwinn, Kimberly D.

Switchgrass is an increasingly important biofuel crop, but knowledge of switchgrass fungal pathogens is not extensive. The purpose of this research was to identify the fungal pathogens that decrease crop yield of switchgrass grown in Tennessee and to investigate a potential sustainable disease management strategy from a value-added by-product of the switchgrass biofuel conversion process. The specific objectives were 1) to identify and characterize prevalent fungal pathogens of switchgrass in Tennessee, 2) assess switchgrass seed produced in the United States for seedborne fungal pathogens, and 3) evaluate switchgrass extractives for antimicrobial activity against plant pathogens.

The non-canonical roles of clathrin and actin in pathogen internalization, egress and spread.

PubMed

Humphries, Ashley C; Way, Michael

2013-08-01

The role of clathrin in pathogen entry has received much attention and has highlighted the adaptability of clathrin during internalization. Recent studies have now uncovered additional roles for clathrin and have put the spotlight on its role in pathogen spread. Here, we discuss the manipulation of clathrin by pathogens, with specific attention to the processes that occur at the plasma membrane. In the majority of cases, both clathrin and the actin cytoskeleton are hijacked, so we also examine the interplay between these two systems and their role during pathogen internalization, egress and spread.

Multiplexed lateral flow microarray assay for detection of citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis pv citri

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

Cary,; Bruce, R; Stubben, Christopher J

The invention provides highly sensitive and specific assays for the major citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis, including a field deployable multiplexed assay capable of rapidly assaying for both pathogens simultaneously. The assays are directed at particular gene targets derived from pathogenic strains that specifically cause the major citrus diseases of citrus variegated chlorosis (Xylella fastidiosa 9a5c) and citrus canker (Xanthomonas axonopodis pv citri). The citrus pathogen assays of the invention offer femtomole sensitivity, excellent linear dynamic range, and rapid and specific detection.

Multiplex detection of respiratory pathogens

DOEpatents

McBride, Mary [Brentwood, CA; Slezak, Thomas [Livermore, CA; Birch, James M [Albany, CA

2012-07-31

Described are kits and methods useful for detection of respiratory pathogens (influenza A (including subtyping capability for H1, H3, H5 and H7 subtypes) influenza B, parainfluenza (type 2), respiratory syncytial virus, and adenovirus) in a sample. Genomic sequence information from the respiratory pathogens was analyzed to identify signature sequences, e.g., polynucleotide sequences useful for confirming the presence or absence of a pathogen in a sample. Primer and probe sets were designed and optimized for use in a PCR based, multiplexed Luminex assay to successfully identify the presence or absence of pathogens in a sample.

Adaptive evolution has targeted the C-terminal domain of the RXLR effectors of plant pathogenic oomycetes.

PubMed

Win, Joe; Kamoun, Sophien

2008-04-01

Plant pathogenic microbes deliver effector proteins inside host cells to modulate plant defense circuitry and enable parasitic colonization. As genome sequences from plant pathogens become available, genome-wide evolutionary analyses will shed light on how pathogen effector genes evolved and adapted to the cellular environment of their host plants. In the August 2007 issue of Plant Cell, we described adaptive evolution (positive selection) in the cytoplasmic RXLR effectors of three recently sequenced oomycete plant pathogens. Here, we summarize our findings and describe additional data that further validate our approach.

[Plasticity of bacterial genomes: pathogenicity islands and the locus of enterocyte effacement (LEE)].

PubMed

Kirsch, Petra; Jores, Jörg; Wieler, Lothar H

2004-01-01

Many bacterial virulence attributes, like toxins, adhesins, invasins, iron uptake systems, are encoded within specific regions of the bacterial genome. These in size varying regions are termed pathogenicity islands (PAIs) since they confer pathogenic properties to the respective micro-organism. Per definition PAIs are exclusively found in pathogenic strains and are often inserted near transfer-RNA genes. Nevertheless, non-pathogenic bacteria also possess foreign DNA elements that confer advantageous features, leading to improved fitness. These additional DNA elements as well as PAIs are termed genomic islands and were acquired during bacterial evolution. Significant G+C content deviation in pathogenicity islands with respect to the rest of the genome, the presence of direct repeat sequences at the flanking regions, the presence of integrase gene determinants as other mobility features,the particular insertion site (tRNA gene) as well as the observed genetic instability suggests that pathogenicity islands were acquired by horizontal gene transfer. PAIs are the fascinating proof of the plasticity of bacterial genomes. PAIs were originally described in human pathogenic Escherichia (E.) coli strains. In the meantime PAIs have been found in various pathogenic bacteria of humans, animals and even plants. The Locus of Enterocyte Effacement (LEE) is one particular widely distributed PAI of E coli. In addition, it also confers pathogenicity to the related species Citrobacter (C.) rodentium and Escherichia (E.) alvei. The LEE is an important virulence feature of several animal pathogens. It is an obligate PAI of all animal and human enteropathogenic E. coli (EPEC), and most enterohaemorrhegic E. coli (EHEC) also harbor the LEE. The LEE encodes a type III secretion system, an adhesion (intimin) that mediates the intimate contact between the bacterium and the epithelial cell, as well as various proteins which are secreted via the type III secretion system. The LEE encoded virulence features are responsible for the formation of so called attaching and effacing (AE) lesions in the intestinal epithelium. Due to its wide distribution in animal pathogens, LEE encoded antigens are suitable vaccine antigens. Acquisition and structure of the LEE pathogenicity island is the crucial point of numerous investigations. However, the evolution of the LEE, its origin and further spread in E. coli, are far from being resolved.

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia.

PubMed

Ewig, S; Torres, A; El-Ebiary, M; Fábregas, N; Hernández, C; González, J; Nicolás, J M; Soto, L

1999-01-01

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

Biofilms in Water, Its role and impact in human disease transmission

DTIC Science & Technology

2008-01-01

increasing realization of the importance of the world’s oceans as a source of potentially pathogenic microorganisms. Human bacterial pathogens...colorimetric microtitre model for the detection of Staphylococcus aureus biofilms. Lett Appl Microbiol 2008, 46:249-254. A new microplate model for...Polz M: Diversity, sources, and detection of human bacterial pathogens in the marine environment. In Oceans and Health: Pathogens in the Marine

Foliar pathogen and insect herbivore effects on two landslide tree species in Puerto Rico

Treesearch

Randall W. Myster

2002-01-01

To better understand pathogen/herbivore interactions and landslide regeneration, percent leaf area lost to disease and herbivory on two Puerto Rican trees over a 1-year period was sampled. Cecropia schreberiana saplings lost from 1 to 3% leaf area to pathogens and from 1 to 7% to herbivores. For Inga vera, both sapling and seedling losses to pathogens were minimal, but...

Transcriptomic analysis reveals the potential of highly pathogenic PRRS virus to modulate immune system activation related to host-pathogen and damage associated signaling in infected porcine monocytes

USDA-ARS?s Scientific Manuscript database

One of the largest risks to the continued stability of the swine industry is by pathogens like porcine reproductive and respiratory syndrome virus (PRRSV) that can decimate production as it spreads among individuals. These infections can be low or highly pathogenic, and because it infects monocytic ...

Biological Control of Aquatic Plants with Pathogenic Fungi

DTIC Science & Technology

1981-01-01

reverse side II necoosary and Ident•l•y by block number) Aquatic plant control Fungi Aquatic plants Pathogenic fungi Biological control Waterhyacinths...BACTERIA ............. ................. D1 2 1 BIOTIGICAL CONTROL OF AQUATIC PLANTS WITH PATHOGENIC FUNGI PART I: INTRODUCTION 1. Plant pathogens have...first noted in Florida. 13. In December of 1973, Dr. K. E. Ctnway isolated a Cercospora species, along with many other fungi , from declining

Species-specific chitin-binding module 18 expansion in the amphibian pathogen Batrachochytrium dendrobatidis.

PubMed

Abramyan, John; Stajich, Jason E

2012-01-01

Batrachochytrium dendrobatidis is the causative agent of chytridiomycosis, which is considered one of the driving forces behind the worldwide decline in populations of amphibians. As a member of the phylum Chytridiomycota, B. dendrobatidis has diverged significantly to emerge as the only pathogen of adult vertebrates. Such shifts in lifestyle are generally accompanied by various degrees of genomic modifications, yet neither its mode of pathogenicity nor any factors associated with it have ever been identified. Presented here is the identification and characterization of a unique expansion of the carbohydrate-binding module family 18 (CBM18), specific to B. dendrobatidis. CBM (chitin-binding module) expansions have been likened to the evolution of pathogenicity in a variety of fungus species, making this expanded group a prime candidate for the identification of potential pathogenicity factors. Furthermore, the CBM18 expansions are confined to three categories of genes, each having been previously implicated in host-pathogen interactions. These correlations highlight this specific domain expansion as a potential key player in the mode of pathogenicity in this unique fungus. The expansion of CBM18 in B. dendrobatidis is exceptional in its size and diversity compared to other pathogenic species of fungi, making this genomic feature unique in an evolutionary context as well as in pathogenicity. Amphibian populations are declining worldwide at an unprecedented rate. Although various factors are thought to contribute to this phenomenon, chytridiomycosis has been identified as one of the leading causes. This deadly fungal disease is cause by Batrachochytrium dendrobatidis, a chytrid fungus species unique in its pathogenicity and, furthermore, its specificity to amphibians. Despite more than two decades of research, the biology of this fungus species and its deadly interaction with amphibians had been notoriously difficult to unravel. Due to the alarming rate of worldwide spread and associated decline in amphibian populations, it is imperative to incorporate novel genomic and genetic techniques into the study of this species. In this study, we present the first reported potential pathogenicity factors in B. dendrobatidis. In silico studies such as this allow us to identify putative targets for more specific molecular analyses, furthering our hope for the control of this pathogen.

Viral etiology, seasonality and severity of hospitalized patients with severe acute respiratory infections in the Eastern Mediterranean Region, 2007-2014.

PubMed

Horton, Katherine C; Dueger, Erica L; Kandeel, Amr; Abdallat, Mohamed; El-Kholy, Amani; Al-Awaidy, Salah; Kohlani, Abdul Hakim; Amer, Hanaa; El-Khal, Abel Latif; Said, Mayar; House, Brent; Pimentel, Guillermo; Talaat, Maha

2017-01-01

Little is known about the role of viral respiratory pathogens in the etiology, seasonality or severity of severe acute respiratory infections (SARI) in the Eastern Mediterranean Region. Sentinel surveillance for SARI was conducted from December 2007 through February 2014 at 20 hospitals in Egypt, Jordan, Oman, Qatar and Yemen. Nasopharyngeal and oropharyngeal swabs were collected from hospitalized patients meeting SARI case definitions and were analyzed for infection with influenza, respiratory syncytial virus (RSV), adenovirus (AdV), human metapneumovirus (hMPV) and human parainfluenza virus types 1-3 (hPIV1-3). We analyzed surveillance data to calculate positivity rates for viral respiratory pathogens, describe the seasonality of those pathogens and determine which pathogens were responsible for more severe outcomes requiring ventilation and/or intensive care and/or resulting in death. At least one viral respiratory pathogen was detected in 8,753/28,508 (30.7%) samples tested for at least one pathogen and 3,497/9,315 (37.5%) of samples tested for all pathogens-influenza in 3,345/28,438 (11.8%), RSV in 3,942/24,503 (16.1%), AdV in 923/9,402 (9.8%), hMPV in 617/9,384 (6.6%), hPIV1 in 159/9,402 (1.7%), hPIV2 in 85/9,402 (0.9%) and hPIV3 in 365/9,402 (3.9%). Multiple pathogens were identified in 501/9,316 (5.4%) participants tested for all pathogens. Monthly variation, indicating seasonal differences in levels of infection, was observed for all pathogens. Participants with hMPV infections and participants less than five years of age were significantly less likely than participants not infected with hMPV and those older than five years of age, respectively, to experience a severe outcome, while participants with a pre-existing chronic disease were at increased risk of a severe outcome, compared to those with no reported pre-existing chronic disease. Viral respiratory pathogens are common among SARI patients in the Eastern Mediterranean Region. Ongoing surveillance is important to monitor changes in the etiology, seasonality and severity of pathogens of interest.

Comparison and optimization of in silico algorithms for predicting the pathogenicity of sodium channel variants in epilepsy.

PubMed

Holland, Katherine D; Bouley, Thomas M; Horn, Paul S

2017-07-01

Variants in neuronal voltage-gated sodium channel α-subunits genes SCN1A, SCN2A, and SCN8A are common in early onset epileptic encephalopathies and other autosomal dominant childhood epilepsy syndromes. However, in clinical practice, missense variants are often classified as variants of uncertain significance when missense variants are identified but heritability cannot be determined. Genetic testing reports often include results of computational tests to estimate pathogenicity and the frequency of that variant in population-based databases. The objective of this work was to enhance clinicians' understanding of results by (1) determining how effectively computational algorithms predict epileptogenicity of sodium channel (SCN) missense variants; (2) optimizing their predictive capabilities; and (3) determining if epilepsy-associated SCN variants are present in population-based databases. This will help clinicians better understand the results of indeterminate SCN test results in people with epilepsy. Pathogenic, likely pathogenic, and benign variants in SCNs were identified using databases of sodium channel variants. Benign variants were also identified from population-based databases. Eight algorithms commonly used to predict pathogenicity were compared. In addition, logistic regression was used to determine if a combination of algorithms could better predict pathogenicity. Based on American College of Medical Genetic Criteria, 440 variants were classified as pathogenic or likely pathogenic and 84 were classified as benign or likely benign. Twenty-eight variants previously associated with epilepsy were present in population-based gene databases. The output provided by most computational algorithms had a high sensitivity but low specificity with an accuracy of 0.52-0.77. Accuracy could be improved by adjusting the threshold for pathogenicity. Using this adjustment, the Mendelian Clinically Applicable Pathogenicity (M-CAP) algorithm had an accuracy of 0.90 and a combination of algorithms increased the accuracy to 0.92. Potentially pathogenic variants are present in population-based sources. Most computational algorithms overestimate pathogenicity; however, a weighted combination of several algorithms increased classification accuracy to >0.90. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Unity in defence: honeybee workers exhibit conserved molecular responses to diverse pathogens.

PubMed

Doublet, Vincent; Poeschl, Yvonne; Gogol-Döring, Andreas; Alaux, Cédric; Annoscia, Desiderato; Aurori, Christian; Barribeau, Seth M; Bedoya-Reina, Oscar C; Brown, Mark J F; Bull, James C; Flenniken, Michelle L; Galbraith, David A; Genersch, Elke; Gisder, Sebastian; Grosse, Ivo; Holt, Holly L; Hultmark, Dan; Lattorff, H Michael G; Le Conte, Yves; Manfredini, Fabio; McMahon, Dino P; Moritz, Robin F A; Nazzi, Francesco; Niño, Elina L; Nowick, Katja; van Rij, Ronald P; Paxton, Robert J; Grozinger, Christina M

2017-03-02

Organisms typically face infection by diverse pathogens, and hosts are thought to have developed specific responses to each type of pathogen they encounter. The advent of transcriptomics now makes it possible to test this hypothesis and compare host gene expression responses to multiple pathogens at a genome-wide scale. Here, we performed a meta-analysis of multiple published and new transcriptomes using a newly developed bioinformatics approach that filters genes based on their expression profile across datasets. Thereby, we identified common and unique molecular responses of a model host species, the honey bee (Apis mellifera), to its major pathogens and parasites: the Microsporidia Nosema apis and Nosema ceranae, RNA viruses, and the ectoparasitic mite Varroa destructor, which transmits viruses. We identified a common suite of genes and conserved molecular pathways that respond to all investigated pathogens, a result that suggests a commonality in response mechanisms to diverse pathogens. We found that genes differentially expressed after infection exhibit a higher evolutionary rate than non-differentially expressed genes. Using our new bioinformatics approach, we unveiled additional pathogen-specific responses of honey bees; we found that apoptosis appeared to be an important response following microsporidian infection, while genes from the immune signalling pathways, Toll and Imd, were differentially expressed after Varroa/virus infection. Finally, we applied our bioinformatics approach and generated a gene co-expression network to identify highly connected (hub) genes that may represent important mediators and regulators of anti-pathogen responses. Our meta-analysis generated a comprehensive overview of the host metabolic and other biological processes that mediate interactions between insects and their pathogens. We identified key host genes and pathways that respond to phylogenetically diverse pathogens, representing an important source for future functional studies as well as offering new routes to identify or generate pathogen resilient honey bee stocks. The statistical and bioinformatics approaches that were developed for this study are broadly applicable to synthesize information across transcriptomic datasets. These approaches will likely have utility in addressing a variety of biological questions.

Bacterial and viral pathogen spectra of acute respiratory infections in under-5 children in hospital settings in Dhaka city

PubMed Central

Bhuyan, Golam Sarower; Hossain, Mohammad Amir; Sarker, Suprovath Kumar; Rahat, Asifuzzaman; Islam, Md Tarikul; Haque, Tanjina Noor; Begum, Noorjahan; Qadri, Syeda Kashfi; Muraduzzaman, A. K. M.; Islam, Nafisa Nawal; Islam, Mohammad Sazzadul; Sultana, Nusrat; Jony, Manjur Hossain Khan; Khanam, Farhana; Mowla, Golam; Matin, Abdul; Begum, Firoza; Shirin, Tahmina; Ahmed, Dilruba; Saha, Narayan; Qadri, Firdausi

2017-01-01

The study aimed to examine for the first time the spectra of viral and bacterial pathogens along with the antibiotic susceptibility of the isolated bacteria in under-5 children with acute respiratory infections (ARIs) in hospital settings of Dhaka, Bangladesh. Nasal swabs were collected from 200 under-five children hospitalized with clinical signs of ARIs. Nasal swabs from 30 asymptomatic children were also collected. Screening of viral pathogens targeted ten respiratory viruses using RT-qPCR. Bacterial pathogens were identified by bacteriological culture methods and antimicrobial susceptibility of the isolates was determined following CLSI guidelines. About 82.5% (n = 165) of specimens were positive for pathogens. Of 165 infected cases, 3% (n = 6) had only single bacterial pathogens, whereas 43.5% (n = 87) cases had only single viral pathogens. The remaining 36% (n = 72) cases had coinfections. In symptomatic cases, human rhinovirus was detected as the predominant virus (31.5%), followed by RSV (31%), HMPV (13%), HBoV (11%), HPIV-3 (10.5%), and adenovirus (7%). Streptococcus pneumoniae was the most frequently isolated bacterial pathogen (9%), whereas Klebsiella pneumaniae, Streptococcus spp., Enterobacter agglomerans, and Haemophilus influenzae were 5.5%, 5%, 2%, and 1.5%, respectively. Of 15 multidrug-resistant bacteria, a Klebsiella pneumoniae isolate and an Enterobacter agglomerans isolate exhibited resistance against more than 10 different antibiotics. Both ARI incidence and predominant pathogen detection rates were higher during post-monsoon and winter, peaking in September. Pathogen detection rates and coinfection incidence in less than 1-year group were significantly higher (P = 0.0034 and 0.049, respectively) than in 1–5 years age group. Pathogen detection rate (43%) in asymptomatic cases was significantly lower compared to symptomatic group (P<0.0001). Human rhinovirus, HPIV-3, adenovirus, Streptococcus pneumonia, and Klebsiella pneumaniae had significant involvement in coinfections with P values of 0.0001, 0.009 and 0.0001, 0.0001 and 0.001 respectively. Further investigations are required to better understand the clinical roles of the isolated pathogens and their seasonality. PMID:28346512

The Z Proteins of Pathogenic but Not Nonpathogenic Arenaviruses Inhibit RIG-i-Like Receptor-Dependent Interferon Production

PubMed Central

Xing, Junji; Ly, Hinh

2014-01-01

ABSTRACT Arenavirus pathogens cause a wide spectrum of diseases in humans ranging from central nervous system disease to lethal hemorrhagic fevers with few treatment options. The reason why some arenaviruses can cause severe human diseases while others cannot is unknown. We find that the Z proteins of all known pathogenic arenaviruses, lymphocytic choriomeningitis virus (LCMV) and Lassa, Junin, Machupo, Sabia, Guanarito, Chapare, Dandenong, and Lujo viruses, can inhibit retinoic acid-inducible gene 1 (RIG-i) and Melanoma Differentiation-Associated protein 5 (MDA5), in sharp contrast to those of 14 other nonpathogenic arenaviruses. Inhibition of the RIG-i-like receptors (RLRs) by pathogenic Z proteins is mediated by the protein-protein interactions of Z and RLRs, which lead to the disruption of the interactions between RLRs and mitochondrial antiviral signaling (MAVS). The Z-RLR interactive interfaces are located within the N-terminal domain (NTD) of the Z protein and the N-terminal CARD domains of RLRs. Swapping of the LCMV Z NTD into the nonpathogenic Pichinde virus (PICV) genome does not affect virus growth in Vero cells but significantly inhibits the type I interferon (IFN) responses and increases viral replication in human primary macrophages. In summary, our results show for the first time an innate immune-system-suppressive mechanism shared by the diverse pathogenic arenaviruses and thus shed important light on the pathogenic mechanism of human arenavirus pathogens. IMPORTANCE We show that all known human-pathogenic arenaviruses share an innate immune suppression mechanism that is based on viral Z protein-mediated RLR inhibition. Our report offers important insights into the potential mechanism of arenavirus pathogenesis, provides a convenient way to evaluate the pathogenic potential of known and/or emerging arenaviruses, and reveals a novel target for the development of broad-spectrum therapies to treat this group of diverse pathogens. More broadly, our report provides a better understanding of the mechanisms of viral immune suppression and host-pathogen interactions. PMID:25552708

A Review of the Interactions between Wheat and Wheat Pathogens: Zymoseptoria tritici, Fusarium spp. and Parastagonospora nodorum

PubMed Central

Duba, Adrian; Goriewa-Duba, Klaudia; Wachowska, Urszula

2018-01-01

Zymoseptoria tritici is a hemibiotrophic pathogen which causes Septoria leaf blotch in wheat. The pathogenesis of the disease consists of a biotrophic phase and a necrotrophic phase. The pathogen infects the host plant by suppressing its immune response in the first stage of infection. Hemibiotrophic pathogens of the genus Fusarium cause Fusarium head blight, and the necrotrophic Parastagonospora nodorum is responsible for Septoria nodorum blotch in wheat. Cell wall-degrading enzymes in plants promote infections by necrotrophic and hemibiotrophic pathogens, and trichothecenes, secondary fungal metabolites, facilitate infections caused by fungi of the genus Fusarium. There are no sources of complete resistance to the above pathogens in wheat. Defense mechanisms in wheat are controlled by many genes encoding resistance traits. In the wheat genome, the characteristic features of loci responsible for resistance to pathogenic infections indicate that at least several dozen genes encode resistance to pathogens. The molecular interactions between wheat and Z. tritici, P. nodorum and Fusarium spp. pathogens have been insufficiently investigated. Most studies focus on the mechanisms by which the hemibiotrophic Z. tritici suppresses immune responses in plants and the role of mycotoxins and effector proteins in infections caused by P. nodorum and Fusarium spp. fungi. Trichothecene glycosylation and effector proteins, which are involved in defense responses in wheat, have been described at the molecular level. Recent advances in molecular biology have produced interesting findings which should be further elucidated in studies of molecular interactions between wheat and fungal pathogens. The Clustered Regularly-Interspaced Short Palindromic Repeats/ CRISPR associated (CRISPR/Cas) system can be used to introduce targeted mutations into the wheat genome and confer resistance to selected fungal diseases. Host-induced gene silencing and spray-induced gene silencing are also useful tools for analyzing wheat–pathogens interactions which can be used to develop new strategies for controlling fungal diseases. PMID:29642627

Coating of silicone with mannoside-PAMAM dendrimers to enhance formation of non-pathogenic Escherichia coli biofilms against colonization of uropathogens.

PubMed

Zhu, Zhiling; Yu, Fei; Chen, Haoqing; Wang, Jun; Lopez, Analette I; Chen, Quan; Li, Siheng; Long, Yuyu; Darouiche, Rabih O; Hull, Richard A; Zhang, Lijuan; Cai, Chengzhi

2017-12-01

Bacterial interference using non-pathogenic Escherichia coli 83972 is a novel strategy for preventing catheter-associated urinary tract infection (CAUTI). Crucial to the success of this strategy is to establish a high coverage and stable biofilm of the non-pathogenic bacteria on the catheter surface. However, this non-pathogenic strain is sluggish to form biofilms on silicone as the most widely used material for urinary catheters. We have addressed this issue by modifying the silicone catheter surfaces with mannosides that promote the biofilm formation, but the stability of the non-pathogenic biofilms challenged by uropathogens over long-term remains a concern. Herein, we report our study on the stability of the non-pathogenic biofilms grown on propynylphenyl mannoside-modified silicone. The result shows that 94% non-pathogenic bacteria were retained on the modified silicone under >0.5 Pa shear stress. After being challenged by three multidrug-resistant uropathogenic isolates in artificial urine for 11 days, large amounts (>4 × 10 6  CFU cm -2 ) of the non-pathogenic bacteria remained on the surfaces. These non-pathogenic biofilms reduced the colonization of the uropathogens by >3.2-log. In bacterial interference, the non-pathogenic Escherichia coli strains are sluggish to form biofilms on the catheter surfaces, due to rapid removal by urine flow. We have demonstrated a solution to this bottleneck by pre-functionalization of mannosides on the silicone surfaces to promote E. coli biofilm formation. A pre-conjugated high affinity propynylphenyl mannoside ligand tethered to the nanometric amino-terminated poly(amido amine) (PAMAM) dendrimer is used for binding to a major E. coli adhesin FimH. It greatly improves the efficiency for the catheter modification, the non-pathogenic biofilm coverage, as well as the (long-term) stability for prevention of uropathogen infections. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A New Classification System for IgG4 Autoantibodies

PubMed Central

Koneczny, Inga

2018-01-01

IgG4 autoimmune diseases are characterized by the presence of antigen-specific autoantibodies of the IgG4 subclass and contain well-characterized diseases such as muscle-specific kinase myasthenia gravis, pemphigus, and thrombotic thrombocytopenic purpura. In recent years, several new diseases were identified, and by now 14 antigens targeted by IgG4 autoantibodies have been described. The IgG4 subclass is considered immunologically inert and functionally monovalent due to structural differences compared to other IgG subclasses. IgG4 usually arises after chronic exposure to antigen and competes with other antibody species, thus “blocking” their pathogenic effector mechanisms. Accordingly, in the context of IgG4 autoimmunity, the pathogenicity of IgG4 is associated with blocking of enzymatic activity or protein–protein interactions of the target antigen. Pathogenicity of IgG4 autoantibodies has not yet been systematically analyzed in IgG4 autoimmune diseases. Here, we establish a modified classification system based on Witebsky’s postulates to determine IgG4 pathogenicity in IgG4 autoimmune diseases, review characteristics and pathogenic mechanisms of IgG4 in these disorders, and also investigate the contribution of other antibody entities to pathophysiology by additional mechanisms. As a result, three classes of IgG4 autoimmune diseases emerge: class I where IgG4 pathogenicity is validated by the use of subclass-specific autoantibodies in animal models and/or in vitro models of pathogenicity; class II where IgG4 pathogenicity is highly suspected but lack validation by the use of subclass specific antibodies in in vitro models of pathogenicity or animal models; and class III with insufficient data or a pathogenic mechanism associated with multivalent antigen binding. Five out of the 14 IgG4 antigens were validated as class I, five as class II, and four as class III. Antibodies of other IgG subclasses or immunoglobulin classes were present in several diseases and could contribute additional pathogenic mechanisms. PMID:29483905

A Model of an Integrated Immune System Pathway in Homo sapiens and Its Interaction with Superantigen Producing Expression Regulatory Pathway in Staphylococcus aureus: Comparing Behavior of Pathogen Perturbed and Unperturbed Pathway

PubMed Central

Tomar, Namrata; De, Rajat K.

2013-01-01

Response of an immune system to a pathogen attack depends on the balance between the host immune defense and the virulence of the pathogen. Investigation of molecular interactions between the proteins of a host and a pathogen helps in identifying the pathogenic proteins. It is necessary to understand the dynamics of a normally behaved host system to evaluate the capacity of its immune system upon pathogen attack. In this study, we have compared the behavior of an unperturbed and pathogen perturbed host system. Moreover, we have developed a formalism under Flux Balance Analysis (FBA) for the optimization of conflicting objective functions. We have constructed an integrated pathway system, which includes Staphylococcal Superantigen (SAg) expression regulatory pathway and TCR signaling pathway of Homo sapiens. We have implemented the method on this pathway system and observed the behavior of host signaling molecules upon pathogen attack. The entire study has been divided into six different cases, based on the perturbed/unperturbed conditions. In other words, we have investigated unperturbed and pathogen perturbed human TCR signaling pathway, with different combinations of optimization of concentrations of regulatory and signaling molecules. One of these cases has aimed at finding out whether minimization of the toxin production in a pathogen leads to the change in the concentration levels of the proteins coded by TCR signaling pathway genes in the infected host. Based on the computed results, we have hypothesized that the balance between TCR signaling inhibitory and stimulatory molecules can keep TCR signaling system into resting/stimulating state, depending upon the perturbation. The proposed integrated host-pathogen interaction pathway model has accurately reflected the experimental evidences, which we have used for validation purpose. The significance of this kind of investigation lies in revealing the susceptible interaction points that can take back the Staphylococcal Enterotoxin (SE)-challenged system within the range of normal behavior. PMID:24324645

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper.

PubMed

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-07-01

Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper

PubMed Central

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-01-01

Background and Aims Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Methods Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Key Results Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. Conclusions The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks. PMID:22437662

Pathogen Phytosensing: Plants to Report Plant Pathogens.

PubMed

Mazarei, Mitra; Teplova, Irina; Hajimorad, M Reza; Stewart, C Neal

2008-04-14

Real-time systems that provide evidence of pathogen contamination in crops can be an important new line of early defense in agricultural centers. Plants possess defense mechanisms to protect against pathogen attack. Inducible plant defense is controlled by signal transduction pathways, inducible promoters and cis-regulatory elements corresponding to key genes involved in defense, and pathogen-specific responses. Identified inducible promoters and cis-acting elements could be utilized in plant sentinels, or 'phytosensors', by fusing these to reporter genes to produce plants with altered phenotypes in response to the presence of pathogens. Here, we have employed cis-acting elements from promoter regions of pathogen inducible genes as well as those responsive to the plant defense signal molecules salicylic acid, jasmonic acid, and ethylene. Synthetic promoters were constructed by combining various regulatory elements supplemented with the enhancer elements from the Cauliflower mosaic virus (CaMV) 35S promoter to increase basal level of the GUS expression. The inducibility of each synthetic promoter was first assessed in transient expression assays using Arabidopsis thaliana protoplasts and then examined for efficacy in stably transgenic Arabidopsis and tobacco plants. Histochemical and fluorometric GUS expression analyses showed that both transgenic Arabidopsis and tobacco plants responded to elicitor and phytohormone treatments with increased GUS expression when compared to untreated plants. Pathogen-inducible phytosensor studies were initiated by analyzing the sensitivity of the synthetic promoters against virus infection. Transgenic tobacco plants infected with Alfalfa mosaic virus showed an increase in GUS expression when compared to mock-inoculated control plants, whereas Tobacco mosaic virus infection caused no changes in GUS expression. Further research, using these transgenic plants against a range of different pathogens with the regulation of detectable reporter gene could provide biological evidence to define the functional differences between pathogens, and provide new technology and applications for transgenic plants as phytosensors.

Importance of Soil Amendments: Survival of Bacterial Pathogens in Manure and Compost Used as Organic Fertilizers.

PubMed

Sharma, Manan; Reynnells, Russell

2016-08-01

Biological soil amendments (BSAs) such as manure and compost are frequently used as organic fertilizers to improve the physical and chemical properties of soils. However, BSAs have been known to be a reservoir for enteric bacterial pathogens such as enterohemorrhagic Escherichia coli (EHEC), Salmonella spp., and Listeria spp. There are numerous mechanisms by which manure may transfer pathogens to growing fruits and vegetables, and several outbreaks of infections have been linked to manure-related contamination of leafy greens. In the United States several commodity-specific guidelines and current and proposed federal rules exist to provide guidance on the application of BSAs as fertilizers to soils, some of which require an interval between the application of manure to soils and the harvest of fruits and vegetables. This review examines the survival, persistence, and regrowth/resuscitation of bacterial pathogens in manure, biosolids, and composts. Moisture, along with climate and the physicochemical properties of soil, manure, or compost, plays a significant role in the ability of pathogens to persist and resuscitate in amended soils. Adaptation of enteric bacterial pathogens to the nonhost environment of soils may also extend their persistence in manure- or compost-amended soils. The presence of antibiotic-resistance genes in soils may also be increased by manure application. Overall, BSAs applied as fertilizers to soils can support the survival and regrowth of pathogens. BSAs should be handled and applied in a manner that reduces the prevalence of pathogens in soils and the likelihood of transfer of food-borne pathogens to fruits and vegetables. This review will focus on two BSAs-raw manure and composted manure (and other feedstocks)-and predominantly on the survival of enteric bacterial pathogens in BSAs as applied to soils as organic fertilizers.

Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 4. Infective doses and pathogen carriage.

PubMed

Todd, Ewen C D; Greig, Judy D; Bartleson, Charles A; Michaels, Barry S

2008-11-01

In this article, the fourth in a series reviewing the role of food workers in foodborne outbreaks, background information on the presence of enteric pathogens in the community, the numbers of organisms required to initiate an infection, and the length of carriage are presented. Although workers have been implicated in outbreaks, they were not always aware of their infections, either because they were in the prodromic phase before symptoms began or because they were asymptomatic carriers. Pathogens of fecal, nose or throat, and skin origin are most likely to be transmitted by the hands, highlighting the need for effective hand hygiene and other barriers to pathogen contamination, such as no bare hand contact with ready-to-eat food. The pathogens most likely to be transmitted by food workers are norovirus, hepatitis A virus, Salmonella, Shigella, and Staphylococcus aureus. However, other pathogens have been implicated in worker-associated outbreaks or have the potential to be implicated. In this study, the likelihood of pathogen involvement in foodborne outbreaks where infected workers have been implicated was examined, based on infectious dose, carriage rate in the community, duration of illness, and length of pathogen excretion. Infectious dose estimates are based on volunteer studies (mostly early experiments) or data from outbreaks. Although there is considerable uncertainty associated with these data, some pathogens appear to be able to infect at doses as low as 1 to 100 units, including viruses, parasites, and some bacteria. Lengthy postsymptomatic shedding periods and excretion by asymptomatic individuals of many enteric pathogens is an important issue for the hygienic management of food workers.

Herpes Simplex Virus Type 1 and Other Pathogens are Key Causative Factors in Sporadic Alzheimer’s Disease

PubMed Central

Harris, Steven A.; Harris, Elizabeth A.

2015-01-01

Abstract This review focuses on research in epidemiology, neuropathology, molecular biology, and genetics regarding the hypothesis that pathogens interact with susceptibility genes and are causative in sporadic Alzheimer’s disease (AD). Sporadic AD is a complex multifactorial neurodegenerative disease with evidence indicating coexisting multi-pathogen and inflammatory etiologies. There are significant associations between AD and various pathogens, including Herpes simplex virus type 1 (HSV-1), Cytomegalovirus, and other Herpesviridae, Chlamydophila pneumoniae, spirochetes, Helicobacter pylori, and various periodontal pathogens. These pathogens are able to evade destruction by the host immune system, leading to persistent infection. Bacterial and viral DNA and RNA and bacterial ligands increase the expression of pro-inflammatory molecules and activate the innate and adaptive immune systems. Evidence demonstrates that pathogens directly and indirectly induce AD pathology, including amyloid-β (Aβ) accumulation, phosphorylation of tau protein, neuronal injury, and apoptosis. Chronic brain infection with HSV-1, Chlamydophila pneumoniae, and spirochetes results in complex processes that interact to cause a vicious cycle of uncontrolled neuroinflammation and neurodegeneration. Infections such as Cytomegalovirus, Helicobacter pylori, and periodontal pathogens induce production of systemic pro-inflammatory cytokines that may cross the blood-brain barrier to promote neurodegeneration. Pathogen-induced inflammation and central nervous system accumulation of Aβ damages the blood-brain barrier, which contributes to the pathophysiology of AD. Apolipoprotein E4 (ApoE4) enhances brain infiltration by pathogens including HSV-1 and Chlamydophila pneumoniae. ApoE4 is also associated with an increased pro-inflammatory response by the immune system. Potential antimicrobial treatments for AD are discussed, including the rationale for antiviral and antibiotic clinical trials. PMID:26401998

Pathogen Loading From Canada Geese Faeces in Freshwater: Potential Risks to Human Health Through Recreational Water Exposure.

PubMed

Gorham, T J; Lee, J

2016-05-01

Canada geese (Branta canadensis) faeces have been shown to contain pathogenic protozoa and bacteria in numerous studies over the past 15 years. Further, increases in both the Canada geese populations and their ideal habitat requirements in the United States (US) translate to a greater presence of these human pathogens in public areas, such as recreational freshwater beaches. Combining these factors, the potential health risk posed by Canada geese faeces at freshwater beaches presents an emerging public health issue that warrants further study. Here, literature concerning human pathogens in Canada geese faeces is reviewed and the potential impacts these pathogens may have on human health are discussed. Pathogens of potential concern include Campylobacter jejuni, Salmonella Typhimurium, Listeria monocytogenes, Helicobacter canadensis, Arcobacter spp., Enterohemorragic Escherichia coli pathogenic strains, Chlamydia psitacci, Cryptosporidium parvum and Giardia lamblia. Scenarios presenting potential exposure to pathogens eluted from faeces include bathers swimming in lakes, children playing with wet and dry sand impacted by geese droppings and other common recreational activities associated with public beaches. Recent recreational water-associated disease outbreaks in the US support the plausibility for some of these pathogens, including Cryptosporidium spp. and C. jejuni, to cause human illness in this setting. In view of these findings and the uncertainties associated with the real health risk posed by Canada geese faecal pathogens to users of freshwater lakes, it is recommended that beach managers use microbial source tracking and conduct a quantitative microbial risk assessment to analyse the local impact of Canada geese on microbial water quality during their decision-making process in beach and watershed management. © 2015 Blackwell Verlag GmbH.

A quantitative synthesis of the role of birds in carrying ticks and tick-borne pathogens in North America.

PubMed

Loss, Scott R; Noden, Bruce H; Hamer, Gabriel L; Hamer, Sarah A

2016-12-01

Birds play a central role in the ecology of tick-borne pathogens. They expand tick populations and pathogens across vast distances and serve as reservoirs that maintain and amplify transmission locally. Research into the role of birds for supporting ticks and tick-borne pathogens has largely been descriptive and focused in small areas. To expand inference beyond these studies, we conducted a quantitative review at the scale of North America to identify avian life history correlates of tick infestation and pathogen prevalence, calculate species-level indices of importance for carrying ticks, and identify research gaps limiting understanding of tick-borne pathogen transmission. Across studies, 78 of 162 bird species harbored ticks, yielding an infestation prevalence of 1981 of 38,929 birds (5.1 %). Avian foraging and migratory strategies interacted to influence infestation. Ground-foraging species, especially non-migratory ground foragers, were disproportionately likely to have high prevalence and intensity of tick infestation. Studies largely focused on Borrelia burgdorferi, the agent of Lyme disease, and non-migratory ground foragers were especially likely to carry B. burgdorferi-infected ticks, a finding that highlights the potential importance of resident birds in local pathogen transmission. Based on infestation indices, all "super-carrier" bird species were passerines. Vast interior areas of North America, many bird and tick species, and most tick-borne pathogens, remain understudied, and research is needed to address these gaps. More studies are needed that quantify tick host preferences, host competence, and spatiotemporal variation in pathogen prevalence and vector and host abundance. This information is crucial for predicting pathogen transmission dynamics under future global change.

A fungal pathogen of amphibians, Batrachochytrium dendrobatidis, attenuates in pathogenicity with in vitro passages.

PubMed

Langhammer, Penny F; Lips, Karen R; Burrowes, Patricia A; Tunstall, Tate; Palmer, Crystal M; Collins, James P

2013-01-01

Laboratory investigations into the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), have accelerated recently, given the pathogen's role in causing the global decline and extinction of amphibians. Studies in which host animals were exposed to Bd have largely assumed that lab-maintained pathogen cultures retained the infective and pathogenic properties of wild isolates. Attenuated pathogenicity is common in artificially maintained cultures of other pathogenic fungi, but to date, it is unknown whether, and to what degree, Bd might change in culture. We compared zoospore production over time in two samples of a single Bd isolate having different passage histories: one maintained in artificial media for more than six years (JEL427-P39), and one recently thawed from cryopreserved stock (JEL427-P9). In a common garden experiment, we then exposed two different amphibian species, Eleutherodactylus coqui and Atelopus zeteki, to both cultures to test whether Bd attenuates in pathogenicity with in vitro passages. The culture with the shorter passage history, JEL427-P9, had significantly greater zoospore densities over time compared to JEL427-P39. This difference in zoospore production was associated with a difference in pathogenicity for a susceptible amphibian species, indicating that fecundity may be an important virulence factor for Bd. In the 130-day experiment, Atelopus zeteki frogs exposed to the JEL427-P9 culture experienced higher average infection intensity and 100% mortality, compared with 60% mortality for frogs exposed to JEL427-P39. This effect was not observed with Eleutherodactylus coqui, which was able to clear infection. We hypothesize that the differences in phenotypic performance observed with Atelopus zeteki are rooted in changes of the Bd genome. Future investigations enabled by this study will focus on the underlying mechanisms of Bd pathogenicity.

Periodontal Pathogens and Risk of Incident Cancer in Postmenopausal Females: The Buffalo OsteoPerio Study

PubMed Central

Mai, Xiaodan; Genco, Robert J.; LaMonte, Michael J.; Hovey, Kathleen M.; Freudenheim, Jo L.; Andrews, Christopher A.; Wactawski-Wende, Jean

2016-01-01

Background Extraoral translocation of oral bacteria may contribute to associations between periodontal disease and cancer. The associations among the presence of three orange-complex periodontal pathogens (Fusobacterium nucleatum, Prevotella intermedia, and Campylobacter rectus), two red-complex periodontal pathogens (Porphyromonas gingivalis and Tannerella forsythia), and cancer risk were investigated. Methods A total of 1,252 postmenopausal females enrolled in the Buffalo Osteoporosis and Periodontal Disease Study were followed prospectively. Baseline subgingival plaque samples were assessed for the presence of periodontal pathogens using indirect immunofluorescence. Incident cancer cases were adjudicated by staff physicians via review of medical records. Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of periodontal pathogens with total cancer and site-specific cancer risk in unadjusted and multivariable-adjusted models. Results Neither the presence of individual pathogens nor the presence of any red-complex pathogens was associated with total cancer or site-specific cancers. Borderline associations were seen among the presence of any orange-complex pathogens (F. nucleatum, P. intermedia, and C. rectus), total cancer risk (HR = 1.35, 95% CI = 1.00 to 1.84), and lung cancer risk (HR = 3.02, 95% CI = 0.98 to 9.29). Conclusions No associations were found between the presence of individual subgingival pathogens and cancer risk. However, there were suggestions of borderline positive associations of the presence of any orange-complex pathogens with total cancer and lung cancer risk. The study is limited by the small number of cancer cases and the assessment of only five oral bacteria. Additional research is needed to understand the possi ble role of periodontal disease in carcinogenesis. PMID:26513268

Microfluidic devices for sample preparation and rapid detection of foodborne pathogens.

PubMed

Kant, Krishna; Shahbazi, Mohammad-Ali; Dave, Vivek Priy; Ngo, Tien Anh; Chidambara, Vinayaka Aaydha; Than, Linh Quyen; Bang, Dang Duong; Wolff, Anders

2018-03-10

Rapid detection of foodborne pathogens at an early stage is imperative for preventing the outbreak of foodborne diseases, known as serious threats to human health. Conventional bacterial culturing methods for foodborne pathogen detection are time consuming, laborious, and with poor pathogen diagnosis competences. This has prompted researchers to call the current status of detection approaches into question and leverage new technologies for superior pathogen sensing outcomes. Novel strategies mainly rely on incorporating all the steps from sample preparation to detection in miniaturized devices for online monitoring of pathogens with high accuracy and sensitivity in a time-saving and cost effective manner. Lab on chip is a blooming area in diagnosis, which exploits different mechanical and biological techniques to detect very low concentrations of pathogens in food samples. This is achieved through streamlining the sample handling and concentrating procedures, which will subsequently reduce human errors and enhance the accuracy of the sensing methods. Integration of sample preparation techniques into these devices can effectively minimize the impact of complex food matrix on pathogen diagnosis and improve the limit of detections. Integration of pathogen capturing bio-receptors on microfluidic devices is a crucial step, which can facilitate recognition abilities in harsh chemical and physical conditions, offering a great commercial benefit to the food-manufacturing sector. This article reviews recent advances in current state-of-the-art of sample preparation and concentration from food matrices with focus on bacterial capturing methods and sensing technologies, along with their advantages and limitations when integrated into microfluidic devices for online rapid detection of pathogens in foods and food production line. Copyright © 2018. Published by Elsevier Inc.

Common themes in microbial pathogenicity revisited.

PubMed Central

Finlay, B B; Falkow, S

1997-01-01

Bacterial pathogens employ a number of genetic strategies to cause infection and, occasionally, disease in their hosts. Many of these virulence factors and their regulatory elements can be divided into a smaller number of groups based on the conservation of similar mechanisms. These common themes are found throughout bacterial virulence factors. For example, there are only a few general types of toxins, despite a large number of host targets. Similarly, there are only a few conserved ways to build the bacterial pilus and nonpilus adhesins used by pathogens to adhere to host substrates. Bacterial entry into host cells (invasion) is a complex mechanism. However, several common invasion themes exist in diverse microorganisms. Similarly, once inside a host cell, pathogens have a limited number of ways to ensure their survival, whether remaining within a host vacuole or by escaping into the cytoplasm. Avoidance of the host immune defenses is key to the success of a pathogen. Several common themes again are employed, including antigenic variation, camouflage by binding host molecules, and enzymatic degradation of host immune components. Most virulence factors are found on the bacterial surface or secreted into their immediate environment, yet virulence factors operate through a relatively small number of microbial secretion systems. The expression of bacterial pathogenicity is dependent upon complex regulatory circuits. However, pathogens use only a small number of biochemical families to express distinct functional factors at the appropriate time that causes infection. Finally, virulence factors maintained on mobile genetic elements and pathogenicity islands ensure that new strains of pathogens evolve constantly. Comprehension of these common themes in microbial pathogenicity is critical to the understanding and study of bacterial virulence mechanisms and to the development of new "anti-virulence" agents, which are so desperately needed to replace antibiotics. PMID:9184008

A hydrodynamics-based approach to evaluating the risk of waterborne pathogens entering drinking water intakes in a large, stratified lake.

PubMed

Hoyer, Andrea B; Schladow, S Geoffrey; Rueda, Francisco J

2015-10-15

Pathogen contamination of drinking water lakes and reservoirs is a severe threat to human health worldwide. A major source of pathogens in surface sources of drinking waters is from body-contact recreation in the water body. However, dispersion pathways of human waterborne pathogens from recreational beaches, where body-contact recreation is known to occur to drinking water intakes, and the associated risk of pathogens entering the drinking water supply remain largely undocumented. A high spatial resolution, three-dimensional hydrodynamic and particle tracking modeling approach has been developed to analyze the risk and mechanisms presented by pathogen dispersion. The pathogen model represents the processes of particle release, transport and survival. Here survival is a function of both water temperature and cumulative exposure to ultraviolet (UV) radiation. Pathogen transport is simulated using a novel and computationally efficient technique of tracking particle trajectories backwards, from a drinking water intake toward their source areas. The model has been applied to a large, alpine lake - Lake Tahoe, CA-NV (USA). The dispersion model results reveal that for this particular lake (1) the risk of human waterborne pathogens to enter drinking water intakes is low, but significant; (2) this risk is strongly related to the depth of the thermocline in relation to the depth of the intake; (3) the risk increases with the seasonal deepening of the surface mixed layer; and (4) the risk increases at night when the surface mixed layer deepens through convective mixing and inactivation by UV radiation is eliminated. While these risk factors will quantitatively vary in different lakes, these same mechanisms will govern the process of transport of pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detailed analysis of metagenome datasets obtained from biogas-producing microbial communities residing in biogas reactors does not indicate the presence of putative pathogenic microorganisms

PubMed Central

2013-01-01

Background In recent years biogas plants in Germany have been supposed to be involved in amplification and dissemination of pathogenic bacteria causing severe infections in humans and animals. In particular, biogas plants are discussed to contribute to the spreading of Escherichia coli infections in humans or chronic botulism in cattle caused by Clostridium botulinum. Metagenome datasets of microbial communities from an agricultural biogas plant as well as from anaerobic lab-scale digesters operating at different temperatures and conditions were analyzed for the presence of putative pathogenic bacteria and virulence determinants by various bioinformatic approaches. Results All datasets featured a low abundance of reads that were taxonomically assigned to the genus Escherichia or further selected genera comprising pathogenic species. Higher numbers of reads were taxonomically assigned to the genus Clostridium. However, only very few sequences were predicted to originate from pathogenic clostridial species. Moreover, mapping of metagenome reads to complete genome sequences of selected pathogenic bacteria revealed that not the pathogenic species itself, but only species that are more or less related to pathogenic ones are present in the fermentation samples analyzed. Likewise, known virulence determinants could hardly be detected. Only a marginal number of reads showed similarity to sequences described in the Microbial Virulence Database MvirDB such as those encoding protein toxins, virulence proteins or antibiotic resistance determinants. Conclusions Findings of this first study of metagenomic sequence reads of biogas producing microbial communities suggest that the risk of dissemination of pathogenic bacteria by application of digestates from biogas fermentations as fertilizers is low, because obtained results do not indicate the presence of putative pathogenic microorganisms in the samples analyzed. PMID:23557021

Actionable exomic incidental findings in 6503 participants: challenges of variant classification.

PubMed

Amendola, Laura M; Dorschner, Michael O; Robertson, Peggy D; Salama, Joseph S; Hart, Ragan; Shirts, Brian H; Murray, Mitzi L; Tokita, Mari J; Gallego, Carlos J; Kim, Daniel Seung; Bennett, James T; Crosslin, David R; Ranchalis, Jane; Jones, Kelly L; Rosenthal, Elisabeth A; Jarvik, Ella R; Itsara, Andy; Turner, Emily H; Herman, Daniel S; Schleit, Jennifer; Burt, Amber; Jamal, Seema M; Abrudan, Jenica L; Johnson, Andrew D; Conlin, Laura K; Dulik, Matthew C; Santani, Avni; Metterville, Danielle R; Kelly, Melissa; Foreman, Ann Katherine M; Lee, Kristy; Taylor, Kent D; Guo, Xiuqing; Crooks, Kristy; Kiedrowski, Lesli A; Raffel, Leslie J; Gordon, Ora; Machini, Kalotina; Desnick, Robert J; Biesecker, Leslie G; Lubitz, Steven A; Mulchandani, Surabhi; Cooper, Greg M; Joffe, Steven; Richards, C Sue; Yang, Yaoping; Rotter, Jerome I; Rich, Stephen S; O'Donnell, Christopher J; Berg, Jonathan S; Spinner, Nancy B; Evans, James P; Fullerton, Stephanie M; Leppig, Kathleen A; Bennett, Robin L; Bird, Thomas; Sybert, Virginia P; Grady, William M; Tabor, Holly K; Kim, Jerry H; Bamshad, Michael J; Wilfond, Benjamin; Motulsky, Arno G; Scott, C Ronald; Pritchard, Colin C; Walsh, Tom D; Burke, Wylie; Raskind, Wendy H; Byers, Peter; Hisama, Fuki M; Rehm, Heidi; Nickerson, Debbie A; Jarvik, Gail P

2015-03-01

Recommendations for laboratories to report incidental findings from genomic tests have stimulated interest in such results. In order to investigate the criteria and processes for assigning the pathogenicity of specific variants and to estimate the frequency of such incidental findings in patients of European and African ancestry, we classified potentially actionable pathogenic single-nucleotide variants (SNVs) in all 4300 European- and 2203 African-ancestry participants sequenced by the NHLBI Exome Sequencing Project (ESP). We considered 112 gene-disease pairs selected by an expert panel as associated with medically actionable genetic disorders that may be undiagnosed in adults. The resulting classifications were compared to classifications from other clinical and research genetic testing laboratories, as well as with in silico pathogenicity scores. Among European-ancestry participants, 30 of 4300 (0.7%) had a pathogenic SNV and six (0.1%) had a disruptive variant that was expected to be pathogenic, whereas 52 (1.2%) had likely pathogenic SNVs. For African-ancestry participants, six of 2203 (0.3%) had a pathogenic SNV and six (0.3%) had an expected pathogenic disruptive variant, whereas 13 (0.6%) had likely pathogenic SNVs. Genomic Evolutionary Rate Profiling mammalian conservation score and the Combined Annotation Dependent Depletion summary score of conservation, substitution, regulation, and other evidence were compared across pathogenicity assignments and appear to have utility in variant classification. This work provides a refined estimate of the burden of adult onset, medically actionable incidental findings expected from exome sequencing, highlights challenges in variant classification, and demonstrates the need for a better curated variant interpretation knowledge base. © 2015 Amendola et al.; Published by Cold Spring Harbor Laboratory Press.

Survival and growth of foodborne pathogens in minimally processed vegetables at 4 and 15 °C.

PubMed

Tian, Jun-Qi; Bae, Young-Min; Choi, Na-Young; Kang, Dong-Hyun; Heu, Sunggi; Lee, Sun-Young

2012-01-01

We conducted this study to investigate the survival and growth of pathogens on fresh vegetables stored at 4 and 15 °C. Vegetables (romaine lettuce, iceberg lettuce, perilla leaves, and sprouts) were inoculated with 4 pathogens (Salmonella enterica serovar Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157:H7) and stored at 2 different temperatures for different periods of time (3, 6, 9, 12, and 15 d at 4 °C and 1, 2, 3, 5, and 7 d at 15 °C). Populations of the 4 pathogens tended to increase on all vegetables stored at 15 °C for 7 d. Populations of E. coli O157:H7 and S. Typhimurium increased significantly, by approximately 2 log₁₀ CFU/g, on loose and head lettuce stored at 15 °C for 1 d. No significant differences were observed in the growth of different pathogens on vegetables stored at 4 °C for 15 d. E. coli O157:H7 did not survive on sprouts stored at 15 or 4 °C. The survival and growth of food pathogens on fresh vegetables were very different depending on the pathogen type and storage temperature. Survivals and growth of pathogens on various vegetables at 4 and 15 °C were observed in this study. Survivals and growth of pathogens on vegetables were different depending on the pathogen type and storage temperature. Therefore, vegetables should be stored under refrigerated conditions (below 4 °C) prior to consumption. This recommendation may vary depending on the type of vegetable. © 2011 Institute of Food Technologists®

Soil pathogen-aphid interactions under differences in soil organic matter and mineral fertilizer.

PubMed

van Gils, Stijn; Tamburini, Giovanni; Marini, Lorenzo; Biere, Arjen; van Agtmaal, Maaike; Tyc, Olaf; Kos, Martine; Kleijn, David; van der Putten, Wim H

2017-01-01

There is increasing evidence showing that microbes can influence plant-insect interactions. In addition, various studies have shown that aboveground pathogens can alter the interactions between plants and insects. However, little is known about the role of soil-borne pathogens in plant-insect interactions. It is also not known how environmental conditions, that steer the performance of soil-borne pathogens, might influence these microbe-plant-insect interactions. Here, we studied effects of the soil-borne pathogen Rhizoctonia solani on aphids (Sitobion avenae) using wheat (Triticum aestivum) as a host. In a greenhouse experiment, we tested how different levels of soil organic matter (SOM) and fertilizer addition influence the interactions between plants and aphids. To examine the influence of the existing soil microbiome on the pathogen effects, we used both unsterilized field soil and sterilized field soil. In unsterilized soil with low SOM content, R. solani addition had a negative effect on aphid biomass, whereas it enhanced aphid biomass in soil with high SOM content. In sterilized soil, however, aphid biomass was enhanced by R. solani addition and by high SOM content. Plant biomass was enhanced by fertilizer addition, but only when SOM content was low, or in the absence of R. solani. We conclude that belowground pathogens influence aphid performance and that the effect of soil pathogens on aphids can be more positive in the absence of a soil microbiome. This implies that experiments studying the effect of pathogens under sterile conditions might not represent realistic interactions. Moreover, pathogen-plant-aphid interactions can be more positive for aphids under high SOM conditions. We recommend that soil conditions should be taken into account in the study of microbe-plant-insect interactions.

High Incidence of Pathogenic Streptococcus agalactiae ST485 Strain in Pregnant/Puerperal Women and Isolation of Hyper-Virulent Human CC67 Strain

PubMed Central

Li, Liping; Wang, Rui; Huang, Yan; Huang, Ting; Luo, Fuguang; Huang, Weiyi; Yang, Xiuying; Lei, Aiying; Chen, Ming; Gan, Xi

2018-01-01

Group B streptococcus (GBS) is the major pathogen causing diseases in neonates, pregnant/puerperal women, cows and fish. Recent studies have shown that GBS may be infectious across hosts and some fish GBS strain might originate from human. The purpose of this study is to investigate the genetic relationship of CC103 strains that recently emerged in cows and humans, and explore the pathogenicity of clinical GBS isolates from human to tilapia. Ninety-two pathogenic GBS isolates were identified from 19 patients with different diseases and their evolution and pathogenicity to tilapia were analyzed. The multilocus sequence typing revealed that clonal complex (CC) 103 strain was isolated from 21.74% (20/92) of patients and ST485 strain was from 14.13% (13/92) patients with multiple diseases including neonates. Genomic evolution analysis showed that both bovine and human CC103 strains alternately form independent evolutionary branches. Three CC67 isolates carried gbs2018-C gene and formed one evolutionary branch with ST61 and ST67 strains that specifically infect dairy cows. Studies of interspecies transmission to tilapia found that 21/92 (22.83%) isolates including all ST23 isolates were highly pathogenic to tilapia and demonstrated that streptococci could break through the blood-brain barrier into brain tissue. In conclusions, CC103 strains are highly prevalent among pathogenic GBS from humans and have evolved into the highly pathogenic ST485 strains specifically infecting humans. The CC67 strains isolated from cows are able to infect humans through evolutionary events of acquiring CC17-specific type C gbs2018 gene and others. Human-derived ST23 pathogenic GBS strains are highly pathogenic to tilapia. PMID:29467722

What is the Risk for Exposure to Vector-Borne Pathogens in United States National Parks?

PubMed Central

EISEN, LARS; WONG, DAVID; SHELUS, VICTORIA; EISEN, REBECCA J.

2015-01-01

United States national parks attract >275 million visitors annually and collectively present risk of exposure for staff and visitors to a wide range of arthropod vector species (most notably fleas, mosquitoes, and ticks) and their associated bacterial, protozoan, or viral pathogens. We assessed the current state of knowledge for risk of exposure to vector-borne pathogens in national parks through a review of relevant literature, including internal National Park Service documents and organismal databases. We conclude that, because of lack of systematic surveillance for vector-borne pathogens in national parks, the risk of pathogen exposure for staff and visitors is unclear. Existing data for vectors within national parks were not based on systematic collections and rarely include evaluation for pathogen infection. Extrapolation of human-based surveillance data from neighboring communities likely provides inaccurate estimates for national parks because landscape differences impact transmission of vector-borne pathogens and human-vector contact rates likely differ inside versus outside the parks because of differences in activities or behaviors. Vector-based pathogen surveillance holds promise to define when and where within national parks the risk of exposure to infected vectors is elevated. A pilot effort, including 5–10 strategic national parks, would greatly improve our understanding of the scope and magnitude of vector-borne pathogen transmission in these high-use public settings. Such efforts also will support messaging to promote personal protection measures and inform park visitors and staff of their responsibility for personal protection, which the National Park Service preservation mission dictates as the core strategy to reduce exposure to vector-borne pathogens in national parks. PMID:23540107

The Use of Filter-feeders to Manage Disease in a Changing World.

PubMed

Burge, Colleen A; Closek, Collin J; Friedman, Carolyn S; Groner, Maya L; Jenkins, Cody M; Shore-Maggio, Amanda; Welsh, Jennifer E

2016-10-01

Rapid environmental change is linked to increases in aquatic disease heightening the need to develop strategies to manage disease. Filter-feeding species are effective biofilters and can naturally mitigate disease risk to humans and wildlife. We review the role of filter-feeders, with an emphasis on bivalves, in altering disease outcomes via augmentation and reduction. Filtration can reduce transmission by removing pathogens from the water column via degradation and release of pathogens in pseudofeces. In other cases, filtration can increase pathogen transmission and disease risk. The effect of filtration on pathogen transmission depends on the selectivity of the filter-feeder, the degree of infectivity by the pathogen, the mechanism(s) of pathogen transmission and the ability of the pathogen to resist degradation. For example, some bacteria and viruses can resist degradation and accumulate within a filter-feeder leading to disease transmission to humans and other wildlife upon ingestion. Since bivalves can concentrate microorganisms, they are also useful as sentinels for the presence of pathogenic microorganisms. While somewhat less studied, other invertebrates, including ascidians and sponges may also provide ecosystem services by altering pathogen transmission. In all scenarios, climate change may affect the potential for filter-feeders to mitigate disease risk. We conclude that an assessment including empirical data and modeling of system-wide impacts should be conducted before selection of filter-feeders to mitigate disease. Such studies should consider physiology of the host and microbe and risk factors for negative impacts including augmentation of other pathogens. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Horse species symposium: a novel approach to monitoring pathogen progression during uterine and placental infection in the mare using bioluminescence imaging technology and lux-modified bacteria.

PubMed

Ryan, P L; Christiansen, D L; Hopper, R M; Walters, F K; Moulton, K; Curbelo, J; Greene, J M; Willard, S T

2011-05-01

Uterine and placental infections are the leading cause of abortion, stillbirth, and preterm delivery in the mare. Whereas uterine and placental infections in women have been studied extensively, a comprehensive examination of the pathogenic processes leading to this unsatisfactory pregnancy outcome in the mare has yet to be completed. Most information in the literature relating to late-term pregnancy loss in mares is based on retrospective studies of clinical cases submitted for necropsy. Here we report the development and application of a novel approach, whereby transgenically modified bacteria transformed with lux genes of Xenorhabdus luminescens or Photorhabdus luminescens origin and biophotonic imaging are utilized to better understand pathogen-induced preterm birth in late-term pregnant mares. This technology uses highly sensitive bioluminescence imaging camera systems to localize and monitor pathogen progression during tissue invasion by measuring the bioluminescent signatures emitted by the lux-modified pathogens. This method has an important advantage in that it allows for the potential tracking of pathogens in vivo in real time and over time, which was hitherto impossible. Although the application of this technology in domestic animals is in its infancy, investigators were successful in identifying the fetal lungs, sinuses, nares, urinary, and gastrointestinal systems as primary tissues for pathogen invasion after experimental infection of pregnant mares with lux-modified Escherichia coli. It is important that pathogens were not detected in other vital organs, such as the liver, brain, and cardiac system. Such precision in localizing sites of pathogen invasion provides potential application for this novel approach in the development of more targeted therapeutic interventions for pathogen-related diseases in the equine and other domestic species.

Mechanisms of action of Coxiella burnetii effectors inferred from host-pathogen protein interactions.

PubMed

Wallqvist, Anders; Wang, Hao; Zavaljevski, Nela; Memišević, Vesna; Kwon, Keehwan; Pieper, Rembert; Rajagopala, Seesandra V; Reifman, Jaques

2017-01-01

Coxiella burnetii is an obligate Gram-negative intracellular pathogen and the etiological agent of Q fever. Successful infection requires a functional Type IV secretion system, which translocates more than 100 effector proteins into the host cytosol to establish the infection, restructure the intracellular host environment, and create a parasitophorous vacuole where the replicating bacteria reside. We used yeast two-hybrid (Y2H) screening of 33 selected C. burnetii effectors against whole genome human and murine proteome libraries to generate a map of potential host-pathogen protein-protein interactions (PPIs). We detected 273 unique interactions between 20 pathogen and 247 human proteins, and 157 between 17 pathogen and 137 murine proteins. We used orthology to combine the data and create a single host-pathogen interaction network containing 415 unique interactions between 25 C. burnetii and 363 human proteins. We further performed complementary pairwise Y2H testing of 43 out of 91 C. burnetii-human interactions involving five pathogen proteins. We used the combined data to 1) perform enrichment analyses of target host cellular processes and pathways, 2) examine effectors with known infection phenotypes, and 3) infer potential mechanisms of action for four effectors with uncharacterized functions. The host-pathogen interaction profiles supported known Coxiella phenotypes, such as adapting cell morphology through cytoskeletal re-arrangements, protein processing and trafficking, organelle generation, cholesterol processing, innate immune modulation, and interactions with the ubiquitin and proteasome pathways. The generated dataset of PPIs-the largest collection of unbiased Coxiella host-pathogen interactions to date-represents a rich source of information with respect to secreted pathogen effector proteins and their interactions with human host proteins.

Use of Metagenomic Shotgun Sequencing Technology To Detect Foodborne Pathogens within the Microbiome of the Beef Production Chain.

PubMed

Yang, Xiang; Noyes, Noelle R; Doster, Enrique; Martin, Jennifer N; Linke, Lyndsey M; Magnuson, Roberta J; Yang, Hua; Geornaras, Ifigenia; Woerner, Dale R; Jones, Kenneth L; Ruiz, Jaime; Boucher, Christina; Morley, Paul S; Belk, Keith E

2016-04-01

Foodborne illnesses associated with pathogenic bacteria are a global public health and economic challenge. The diversity of microorganisms (pathogenic and nonpathogenic) that exists within the food and meat industries complicates efforts to understand pathogen ecology. Further, little is known about the interaction of pathogens within the microbiome throughout the meat production chain. Here, a metagenomic approach and shotgun sequencing technology were used as tools to detect pathogenic bacteria in environmental samples collected from the same groups of cattle at different longitudinal processing steps of the beef production chain: cattle entry to feedlot, exit from feedlot, cattle transport trucks, abattoir holding pens, and the end of the fabrication system. The log read counts classified as pathogens per million reads for Salmonella enterica,Listeria monocytogenes,Escherichia coli,Staphylococcus aureus, Clostridium spp. (C. botulinum and C. perfringens), and Campylobacter spp. (C. jejuni,C. coli, and C. fetus) decreased over subsequential processing steps. Furthermore, the normalized read counts for S. enterica,E. coli, and C. botulinumwere greater in the final product than at the feedlots, indicating that the proportion of these bacteria increased (the effect on absolute numbers was unknown) within the remaining microbiome. From an ecological perspective, data indicated that shotgun metagenomics can be used to evaluate not only the microbiome but also shifts in pathogen populations during beef production. Nonetheless, there were several challenges in this analysis approach, one of the main ones being the identification of the specific pathogen from which the sequence reads originated, which makes this approach impractical for use in pathogen identification for regulatory and confirmation purposes. Copyright © 2016 Yang et al.

Rapid Waterborne Pathogen Detection with Mobile Electronics.

PubMed

Wu, Tsung-Feng; Chen, Yu-Chen; Wang, Wei-Chung; Kucknoor, Ashwini S; Lin, Che-Jen; Lo, Yu-Hwa; Yao, Chun-Wei; Lian, Ian

2017-06-09

Pathogen detection in water samples, without complex and time consuming procedures such as fluorescent-labeling or culture-based incubation, is essential to public safety. We propose an immunoagglutination-based protocol together with the microfluidic device to quantify pathogen levels directly from water samples. Utilizing ubiquitous complementary metal-oxide-semiconductor (CMOS) imagers from mobile electronics, a low-cost and one-step reaction detection protocol is developed to enable field detection for waterborne pathogens. 10 mL of pathogen-containing water samples was processed using the developed protocol including filtration enrichment, immune-reaction detection and imaging processing. The limit of detection of 10 E. coli O157:H7 cells/10 mL has been demonstrated within 10 min of turnaround time. The protocol can readily be integrated into a mobile electronics such as smartphones for rapid and reproducible field detection of waterborne pathogens.

Genes, communities & invasive species: understanding the ecological and evolutionary dynamics of host-pathogen interactions.

PubMed

Burdon, J J; Thrall, P H; Ericson, L

2013-08-01

Reciprocal interactions between hosts and pathogens drive ecological, epidemiological and co-evolutionary trajectories, resulting in complex patterns of diversity at population, species and community levels. Recent results confirm the importance of negative frequency-dependent rather than 'arms-race' processes in the evolution of individual host-pathogen associations. At the community level, complex relationships between species abundance and diversity dampen or alter pathogen impacts. Invasive pathogens challenge these controls reflecting the earliest stages of evolutionary associations (akin to arms-race) where disease effects may be so great that they overwhelm the host's and community's ability to respond. Viewing these different stabilization/destabilization phases as a continuum provides a valuable perspective to assessment of the role of genetics and ecology in the dynamics of both natural and invasive host-pathogen associations. Copyright © 2013 Elsevier Ltd. All rights reserved.

Independently evolved virulence effectors converge onto hubs in a plant immune system network.

PubMed

Mukhtar, M Shahid; Carvunis, Anne-Ruxandra; Dreze, Matija; Epple, Petra; Steinbrenner, Jens; Moore, Jonathan; Tasan, Murat; Galli, Mary; Hao, Tong; Nishimura, Marc T; Pevzner, Samuel J; Donovan, Susan E; Ghamsari, Lila; Santhanam, Balaji; Romero, Viviana; Poulin, Matthew M; Gebreab, Fana; Gutierrez, Bryan J; Tam, Stanley; Monachello, Dario; Boxem, Mike; Harbort, Christopher J; McDonald, Nathan; Gai, Lantian; Chen, Huaming; He, Yijian; Vandenhaute, Jean; Roth, Frederick P; Hill, David E; Ecker, Joseph R; Vidal, Marc; Beynon, Jim; Braun, Pascal; Dangl, Jeffery L

2011-07-29

Plants generate effective responses to infection by recognizing both conserved and variable pathogen-encoded molecules. Pathogens deploy virulence effector proteins into host cells, where they interact physically with host proteins to modulate defense. We generated an interaction network of plant-pathogen effectors from two pathogens spanning the eukaryote-eubacteria divergence, three classes of Arabidopsis immune system proteins, and ~8000 other Arabidopsis proteins. We noted convergence of effectors onto highly interconnected host proteins and indirect, rather than direct, connections between effectors and plant immune receptors. We demonstrated plant immune system functions for 15 of 17 tested host proteins that interact with effectors from both pathogens. Thus, pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life-cycle strategies.

Pharmacological Targeting of the Host-Pathogen Interaction: Alternatives to Classical Antibiotics to Combat Drug-Resistant Superbugs

PubMed Central

Munguia, Jason; Nizet, Victor

2017-01-01

The rise of multidrug-resistant pathogens and the dearth of new antibiotic development place an existential strain on successful infectious disease therapy. Breakthrough strategies that go beyond classical antibiotic mechanisms are needed to combat this looming public health catastrophe. Reconceptualizing antibiotic therapy in the richer context of the host-pathogen interaction is required for innovative solutions. By defining specific virulence factors, the essence of a pathogen, and pharmacologically neutralizing their activities, one can block disease progression and sensitize microbes to immune clearance. Likewise, host-directed strategies to boost phagocyte bactericidal activity, enhance leukocyte recruitment, or reverse pathogen-induced immunosuppression seek to replicate the success of cancer immunotherapy in the field of infectious diseases. The answer to the threat of multidrug-resistant pathogens lies “outside-the-box” of current antibiotic paradigms. PMID:28283200

Intersections between immune responses and morphological regulation in plants.

PubMed

Uchida, Naoyuki; Tasaka, Masao

2010-06-01

Successful plant pathogens have developed strategies to interfere with the defence mechanisms of their host plants through evolution. Conversely, host plants have evolved systems to counteract pathogen attack. Some pathogens induce pathogenic symptoms on plants that include morphological changes in addition to interference with plant growth. Recent studies, based on molecular biology and genetics using Arabidopsis thaliana, have revealed that factors derived from pathogens can modulate host systems and/or host factors that play important roles in the morphological regulation of host plants. Other reports, meanwhile, have shown that factors known to have roles in plant morphology also function in plant immune responses. Evolutionary conservation of these factors and systems implies that host-pathogen interactions and the evolution they drive have yielded tight links between morphological processes and immune responses. In this review, recent findings about these topics are introduced and discussed.

Novel utilization of the outer membrane proteins for the identification and differentiation of pathogenic versus nonpathogenic microbial strains using mass spectrometry-based proteomics approach

NASA Astrophysics Data System (ADS)

Jabbour, Rabih E.; Wade, Mary; Deshpande, Samir V.; McCubbin, Patrick; Snyder, A. Peter; Bevilacqua, Vicky

2012-06-01

Mass spectrometry based proteomic approaches are showing promising capabilities in addressing various biological and biochemical issues. Outer membrane proteins (OMPs) are often associated with virulence in gram-negative pathogens and could prove to be excellent model biomarkers for strain level differentiation among bacteria. Whole cells and OMP extracts were isolated from pathogenic and non-pathogenic strains of Francisella tularensis, Burkholderia thailandensis, and Burkholderia mallei. OMP extracts were compared for their ability to differentiate and delineate the correct database organism to an experimental sample and for the degree of dissimilarity to the nearest-neighbor database strains. This study addresses the comparative experimental proteome analyses of OMPs vs. whole cell lysates on the strain-level discrimination among gram negative pathogenic and non-pathogenic strains.

Commensal or pathogen – a challenge to fulfil Koch’s Postulates

PubMed Central

Hess, M.

2017-01-01

ABSTRACT 1. Infectious diseases have a large impact on poultry health and economics. Elucidating the pathogenesis of a certain disease is crucial to implement control strategies. 2. Multiplication of a pathogen and its characterisation in vitro are basic requirements to perform experimental studies. However, passaging of the pathogen in vitro can influence the pathogenicity, a process targeted for live vaccine development, but limits the reproduction of clinical signs. 3. Numerous factors can influence the outcome of experimental infections with some importance on the pathogen, application route and host as exemplarily outlined for Histomonas meleagridis, Gallibacterium anatis and fowl aviadenoviruses (FAdVs). 4. In future, more comprehensive and detailed settings are needed to obtain as much information as possible from animal experiments. Processing of samples with modern diagnostic tools provides the option to closely monitor the host–pathogen interaction. PMID:27724044

Climate warming and disease risks for terrestrial and marine biota

USGS Publications Warehouse

Harvell, C.D.; Mitchell, C.E.; Ward, J.R.; Altizer, S.; Dobson, A.P.; Ostfeld, R.S.; Samuel, M.D.

2002-01-01

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño–Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.

Climate Warming and Disease Risks for Terrestrial and Marine Biota

NASA Astrophysics Data System (ADS)

Harvell, C. Drew; Mitchell, Charles E.; Ward, Jessica R.; Altizer, Sonia; Dobson, Andrew P.; Ostfeld, Richard S.; Samuel, Michael D.

2002-06-01

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño-Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.

Benefits of Genomic Insights and CRISPR-Cas Signatures to Monitor Potential Pathogens across Drinking Water Production and Distribution Systems

PubMed Central

Zhang, Ya; Kitajima, Masaaki; Whittle, Andrew J.; Liu, Wen-Tso

2017-01-01

The occurrence of pathogenic bacteria in drinking water distribution systems (DWDSs) is a major health concern, and our current understanding is mostly related to pathogenic species such as Legionella pneumophila and Mycobacterium avium but not to bacterial species closely related to them. In this study, genomic-based approaches were used to characterize pathogen-related species in relation to their abundance, diversity, potential pathogenicity, genetic exchange, and distribution across an urban drinking water system. Nine draft genomes recovered from 10 metagenomes were identified as Legionella (4 draft genomes), Mycobacterium (3 draft genomes), Parachlamydia (1 draft genome), and Leptospira (1 draft genome). The pathogenicity potential of these genomes was examined by the presence/absence of virulence machinery, including genes belonging to Type III, IV, and VII secretion systems and their effectors. Several virulence factors known to pathogenic species were detected with these retrieved draft genomes except the Leptospira-related genome. Identical clustered regularly interspaced short palindromic repeats-CRISPR-associated proteins (CRISPR-Cas) genetic signatures were observed in two draft genomes recovered at different stages of the studied system, suggesting that the spacers in CRISPR-Cas could potentially be used as a biomarker in the monitoring of Legionella related strains at an evolutionary scale of several years across different drinking water production and distribution systems. Overall, metagenomics approach was an effective and complementary tool of culturing techniques to gain insights into the pathogenic characteristics and the CRISPR-Cas signatures of pathogen-related species in DWDSs. PMID:29097994

Predators indirectly reduce the prevalence of an insect-vectored plant pathogen independent of predator diversity.

PubMed

Long, Elizabeth Y; Finke, Deborah L

2015-04-01

A widely cited benefit of predator diversity is greater suppression of insect herbivores, with corresponding increases in plant biomass. In the context of a vector-borne pathogen system, predator species richness may also influence plant disease risk via the direct effects of predators on the abundance and behavior of herbivores that also act as pathogen vectors. Using an assemblage of generalist insect predators, we examined the relationship between predator species richness and the prevalence of the aphid-vectored cereal yellow dwarf virus in wheat. We found that increasing predator richness enhanced suppression of the vector population and that pathogen prevalence was reduced when predators were present, but the reduction in prevalence was independent of predator species richness. To determine the mechanism(s) by which predator species richness contributes to vector suppression, but not pathogen prevalence, we evaluated vector movement and host plant occupancy in response to predator treatments. We found that pathogen prevalence was unrelated to vector suppression because host plant occupancy by vectors did not vary as a function of vector abundance. However, the presence of predators reduced pathogen prevalence because predators stimulated greater plant-to-plant movement by vectors, which likely diminished vector feeding time and reduced the transmission efficiency of this persistent pathogen. We conclude that community structure (i.e., the presence of predators), but not predator diversity, is a potential factor influencing local plant infection by this insect-vectored pathogen.

Honey bee (Apis mellifera) colony health and pathogen composition in migratory beekeeping operations involved in California almond pollination

PubMed Central

Daughenbaugh, Katie F.; Radford, Rosemarie; Kegley, Susan E.

2017-01-01

Honey bees are important pollinators of agricultural crops. Pathogens and other factors have been implicated in high annual losses of honey bee colonies in North America and some European countries. To further investigate the relationship between multiple factors, including pathogen prevalence and abundance and colony health, we monitored commercially managed migratory honey bee colonies involved in California almond pollination in 2014. At each sampling event, honey bee colony health was assessed, using colony population size as a proxy for health, and the prevalence and abundance of seven honey bee pathogens was evaluated using PCR and quantitative PCR, respectively. In this sample cohort, pathogen prevalence and abundance did not correlate with colony health, but did correlate with the date of sampling. In general, pathogen prevalence (i.e., the number of specific pathogens harbored within a colony) was lower early in the year (January—March) and was greater in the summer, with peak prevalence occurring in June. Pathogen abundance in individual honey bee colonies varied throughout the year and was strongly associated with the sampling date, and was influenced by beekeeping operation, colony health, and mite infestation level. Together, data from this and other observational cohort studies that monitor individual honey bee colonies and precisely account for sampling date (i.e., day of year) will lead to a better understanding of the influence of pathogens on colony mortality and the effects of other factors on these associations. PMID:28817641

Worldwide distribution and diversity of seabird ticks: implications for the ecology and epidemiology of tick-borne pathogens.

PubMed

Dietrich, Muriel; Gómez-Díaz, Elena; McCoy, Karen D

2011-05-01

The ubiquity of ticks and their importance in the transmission of pathogens involved in human and livestock diseases are reflected by the growing number of studies focusing on tick ecology and the epidemiology of tick-borne pathogens. Likewise, the involvement of wild birds in dispersing pathogens and their role as reservoir hosts are now well established. However, studies on tick-bird systems have mainly focused on land birds, and the role of seabirds in the ecology and epidemiology of tick-borne pathogens is rarely considered. Seabirds typically have large population sizes, wide geographic distributions, and high mobility, which make them significant potential players in the maintenance and dispersal of disease agents at large spatial scales. They are parasitized by at least 29 tick species found across all biogeographical regions of the world. We know that these seabird-tick systems can harbor a large diversity of pathogens, although detailed studies of this diversity remain scarce. In this article, we review current knowledge on the diversity and global distribution of ticks and tick-borne pathogens associated with seabirds. We discuss the relationship between seabirds, ticks, and their pathogens and examine the interesting characteristics of these relationships from ecological and epidemiological points of view. We also highlight some future research directions required to better understand the evolution of these systems and to assess the potential role of seabirds in the epidemiology of tick-borne pathogens.

Phytosterols Play a Key Role in Plant Innate Immunity against Bacterial Pathogens by Regulating Nutrient Efflux into the Apoplast1[C][W][OA

PubMed Central

Wang, Keri; Senthil-Kumar, Muthappa; Ryu, Choong-Min; Kang, Li; Mysore, Kirankumar S.

2012-01-01

Bacterial pathogens colonize a host plant by growing between the cells by utilizing the nutrients present in apoplastic space. While successful pathogens manipulate the plant cell membrane to retrieve more nutrients from the cell, the counteracting plant defense mechanism against nonhost pathogens to restrict the nutrient efflux into the apoplast is not clear. To identify the genes involved in nonhost resistance against bacterial pathogens, we developed a virus-induced gene-silencing-based fast-forward genetics screen in Nicotiana benthamiana. Silencing of N. benthamiana SQUALENE SYNTHASE, a key gene in phytosterol biosynthesis, not only compromised nonhost resistance to few pathovars of Pseudomonas syringae and Xanthomonas campestris, but also enhanced the growth of the host pathogen P. syringae pv tabaci by increasing nutrient efflux into the apoplast. An Arabidopsis (Arabidopsis thaliana) sterol methyltransferase mutant (sterol methyltransferase2) involved in sterol biosynthesis also compromised plant innate immunity against bacterial pathogens. The Arabidopsis cytochrome P450 CYP710A1, which encodes C22-sterol desaturase that converts β-sitosterol to stigmasterol, was dramatically induced upon inoculation with nonhost pathogens. An Arabidopsis Atcyp710A1 null mutant compromised both nonhost and basal resistance while overexpressors of AtCYP710A1 enhanced resistance to host pathogens. Our data implicate the involvement of sterols in plant innate immunity against bacterial infections by regulating nutrient efflux into the apoplast. PMID:22298683

Competition between yogurt probiotics and periodontal pathogens in vitro.

PubMed

Zhu, Yunwo; Xiao, Liying; Shen, Da; Hao, Yuqing

2010-09-01

To investigate the competition between probiotics in bio-yogurt and periodontal pathogens in vitro. The antimicrobial activity of bio-yogurt was studied by agar diffusion assays, using eight species of putative periodontal pathogens and a 'protective bacteria' as indicator strains. Four probiotic bacterial species (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, and Bifidobacterium) were isolated from yogurt and used to rate the competitive exclusion between probiotics and periodontal pathogens. Fresh yogurt inhibited all the periodontal pathogens included in this work, showing inhibition zones ranging from 9.3 (standard deviation 0.6) mm to 17.3 (standard deviation 1.7) mm, whereas heat-treated yogurt showed lower antimicrobial activity. In addition, neither fresh yogurt nor heat-treated yogurt inhibited the 'protective bacteria', Streptococcus sanguinis. The competition between yogurt probiotics and periodontal pathogens depended on the sequence of inoculation. When probiotics were inoculated first, Bifidobacterium inhibited Porphyromonas gingivalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas circumdentaria, and Prevotella nigrescens; L. acidophilus inhibited P. gingivalis, A. actinomycetemcomitans, P. circumdentaria, P. nigrescens, and Peptostreptococcus anaerobius; L. bulgaricus inhibited P. gingivalis, A. actinomycetemcomitans, and P. nigrescens; and S. thermophilus inhibited P. gingivalis, F. nucleatum, and P. nigrescens. However, their antimicrobial properties were reduced when both species (probiotics and periodontal pathogens) were inoculated simultaneously. When periodontal pathogens were inoculated first, Prevotella intermedia inhibited Bifidobacterium and S. thermophilus. The results demonstrated that bio-yogurt and the probiotics that it contains are capable of inhibiting specific periodontal pathogens but have no effect on the periodontal protective bacteria.

Pathogen survival trajectories: an eco-environmental approach to the modeling of human campylobacteriosis ecology.

PubMed Central

Skelly, Chris; Weinstein, Phil

2003-01-01

Campylobacteriosis, like many human diseases, has its own ecology in which the propagation of human infection and disease depends on pathogen survival and finding new hosts in order to replicate and sustain the pathogen population. The complexity of this process, a process common to other enteric pathogens, has hampered control efforts. Many unknowns remain, resulting in a poorly understood disease ecology. To provide structure to these unknowns and help direct further research and intervention, we propose an eco-environmental modeling approach for campylobacteriosis. This modeling approach follows the pathogen population as it moves through the environments that define the physical structure of its ecology. In this paper, we term the ecologic processes and environments through which these populations move "pathogen survival trajectories." Although such a modeling approach could have veterinary applications, our emphasis is on human campylobacteriosis and focuses on human exposures to Campylobacter through feces, food, and aquatic environments. The pathogen survival trajectories that lead to human exposure include ecologic filters that limit population size, e.g., cooking food to kill Campylobacter. Environmental factors that influence the size of the pathogen reservoirs include temperature, nutrient availability, and moisture availability during the period of time the pathogen population is moving through the environment between infected and susceptible hosts. We anticipate that the modeling approach proposed here will work symbiotically with traditional epidemiologic and microbiologic research to help guide and evaluate the acquisition of new knowledge about the ecology, eventual intervention, and control of campylobacteriosis. PMID:12515674

Comparison of fecal indicators with pathogenic bacteria and rotavirus in groundwater.

PubMed

Ferguson, Andrew S; Layton, Alice C; Mailloux, Brian J; Culligan, Patricia J; Williams, Daniel E; Smartt, Abby E; Sayler, Gary S; Feighery, John; McKay, Larry D; Knappett, Peter S K; Alexandrova, Ekaterina; Arbit, Talia; Emch, Michael; Escamilla, Veronica; Ahmed, Kazi Matin; Alam, Md Jahangir; Streatfield, P Kim; Yunus, Mohammad; van Geen, Alexander

2012-08-01

Groundwater is routinely analyzed for fecal indicators but direct comparisons of fecal indicators to the presence of bacterial and viral pathogens are rare. This study was conducted in rural Bangladesh where the human population density is high, sanitation is poor, and groundwater pumped from shallow tubewells is often contaminated with fecal bacteria. Five indicator microorganisms (E. coli, total coliform, F+RNA coliphage, Bacteroides and human-associated Bacteroides) and various environmental parameters were compared to the direct detection of waterborne pathogens by quantitative PCR in groundwater pumped from 50 tubewells. Rotavirus was detected in groundwater filtrate from the largest proportion of tubewells (40%), followed by Shigella (10%), Vibrio (10%), and pathogenic E. coli (8%). Spearman rank correlations and sensitivity-specificity calculations indicate that some, but not all, combinations of indicators and environmental parameters can predict the presence of pathogens. Culture-dependent fecal indicator bacteria measured on a single date did not predict total bacterial pathogens, but annually averaged monthly measurements of culturable E. coli did improve prediction for total bacterial pathogens. A qPCR-based E. coli assay was the best indicator for the bacterial pathogens. F+RNA coliphage were neither correlated nor sufficiently sensitive towards rotavirus, but were predictive of bacterial pathogens. Since groundwater cannot be excluded as a significant source of diarrheal disease in Bangladesh and neighboring countries with similar characteristics, the need to develop more effective methods for screening tubewells with respect to microbial contamination is necessary. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of fecal indicators with pathogenic bacteria and rotavirus in groundwater

PubMed Central

Ferguson, Andrew S.; Layton, Alice C.; Mailloux, Brian J; Culligan, Patricia J.; Williams, Daniel E.; Smartt, Abby E.; Sayler, Gary S.; Feighery, John; McKay, Larry; Knappett, Peter S.K.; Alexandrova, Ekaterina; Arbit, Talia; Emch, Michael; Escamilla, Veronica; Ahmed, Kazi Matin; Alam, Md. Jahangir; Streatfield, P. Kim; Yunus, Mohammad; van Geen, Alexander

2012-01-01

Groundwater is routinely analyzed for fecal indicators but direct comparisons of fecal indicators to the presence of bacterial and viral pathogens are rare. This study was conducted in rural Bangladesh where the human population density is high, sanitation is poor, and groundwater pumped from shallow tubewells is often contaminated with fecal bacteria. Five indicator microorganisms (E. coli, total coliform, F+RNA coliphage, Bacteroides and human-associated Bacteroides) and various environmental parameters were compared to the direct detection of waterborne pathogens by quantitative PCR in groundwater pumped from 50 tubewells. Rotavirus was detected in groundwater filtrate from the largest proportion of tubewells (40%), followed by Shigella (10%), Vibrio (10%), and pathogenic E. coli (8%). Spearman rank correlations and sensitivity-specificity calculations indicate that some, but not all, combinations of indicators and environmental parameters can predict the presence of pathogens. Culture-dependent fecal indicator bacteria measured on a single date did not predict total bacterial pathogens, but annually averaged monthly measurements of culturable E. coli did improve prediction for total bacterial pathogens. A qPCR-based E. coli assay was the best indicator for the bacterial pathogens. F+RNA coliphage were neither correlated nor sufficiently sensitive towards rotavirus, but were predictive of bacterial pathogens. Since groundwater cannot be excluded as a significant source of diarrheal disease in Bangladesh and neighboring countries with similar characteristics, the need to develop more effective methods for screening tubewells with respect to microbial contamination is necessary. PMID:22705866

Honey bee (Apis mellifera) colony health and pathogen composition in migratory beekeeping operations involved in California almond pollination.

PubMed

Glenny, William; Cavigli, Ian; Daughenbaugh, Katie F; Radford, Rosemarie; Kegley, Susan E; Flenniken, Michelle L

2017-01-01

Honey bees are important pollinators of agricultural crops. Pathogens and other factors have been implicated in high annual losses of honey bee colonies in North America and some European countries. To further investigate the relationship between multiple factors, including pathogen prevalence and abundance and colony health, we monitored commercially managed migratory honey bee colonies involved in California almond pollination in 2014. At each sampling event, honey bee colony health was assessed, using colony population size as a proxy for health, and the prevalence and abundance of seven honey bee pathogens was evaluated using PCR and quantitative PCR, respectively. In this sample cohort, pathogen prevalence and abundance did not correlate with colony health, but did correlate with the date of sampling. In general, pathogen prevalence (i.e., the number of specific pathogens harbored within a colony) was lower early in the year (January-March) and was greater in the summer, with peak prevalence occurring in June. Pathogen abundance in individual honey bee colonies varied throughout the year and was strongly associated with the sampling date, and was influenced by beekeeping operation, colony health, and mite infestation level. Together, data from this and other observational cohort studies that monitor individual honey bee colonies and precisely account for sampling date (i.e., day of year) will lead to a better understanding of the influence of pathogens on colony mortality and the effects of other factors on these associations.

Prevalence of Bovine Viral Diarrhoea Virus (BVDV), Bovine Herpes Virus 1 (BHV 1), Leptospirosis and Neosporosis, and associated risk factors in 161 Irish beef herds.

PubMed

Barrett, Damien; Parr, Mervyn; Fagan, John; Johnson, Alan; Tratalos, Jamie; Lively, Francis; Diskin, Michael; Kenny, David

2018-01-06

There are limited data available, in Ireland or elsewhere, to determine the extent of exposure to various endemic diseases among beef cows and factors associated with exposure to causative pathogens. The objectives of this study were to determine the herd and within herd prevalence of Bovine Viral Diarrhoea Virus (BVDV), Bovine Herpes Virus 1 (BHV-1), Leptospirosis and Neosporosis in a large scale study of commercial beef herds on the island of Ireland, and to examine herd level factors associated with exposure to these pathogens in these herds. The average number of cows tested per herd was 35.5 (median 30). Herd level seroprevalence to Bovine Herpesvirus-1(BHV-1), Bovine Viral-Diarrhoea Virus (BVDV), Leptospirosis and Neosporosis was 90%, 100%, 91% and 67%, respectively, while the mean within herd prevalence for the these pathogens was 40%, 77.7%, 65.7% and 5.7%, respectively. The study confirms that the level of seroconversion for the four pathogens of interest increases with herd size. There was also evidence that exposure to one pathogen may increase the risk of exposure to another pathogen. Herd level seroprevalences were in excess of 90% for BVDV, BHV-1 and Leptosporosis. Larger herds were subject to increased exposure to disease pathogens. This study suggests that exposure to several pathogens may be associated with the further exposure to other pathogens.

Effects of phenotypic plasticity on pathogen transmission in the field in a Lepidoptera-NPV system.

PubMed

Reeson, A F; Wilson, K; Cory, J S; Hankard, P; Weeks, J M; Goulson, D; Hails, R S

2000-08-01

In models of insect-pathogen interactions, the transmission parameter (ν) is the term that describes the efficiency with which pathogens are transmitted between hosts. There are two components to the transmission parameter, namely the rate at which the host encounters pathogens (contact rate) and the rate at which contact between host and pathogen results in infection (host susceptibility). Here it is shown that in larvae of Spodoptera exempta (Lepidoptera: Noctuidae), in which rearing density triggers the expression of one of two alternative phenotypes, the high-density morph is associated with an increase in larval activity. This response is likely to result in an increase in the contact rate between hosts and pathogens. Rearing density is also known to affect susceptibility of S. exempta to pathogens, with the high-density morph showing increased resistance to a baculovirus. In order to determine whether density-dependent differences observed in the laboratory might affect transmission in the wild, a field trial was carried out to estimate the transmission parameter for S. exempta and its nuclear polyhedrosis virus (NPV). The transmission parameter was found to be significantly higher among larvae reared in isolation than among those reared in crowds. Models of insect-pathogen interactions, in which the transmission parameter is assumed to be constant, will therefore not fully describe the S. exempta-NPV system. The finding that crowding can influence transmission in this way has major implications for both the long-term population dynamics and the invasion dynamics of insect-pathogen systems.

Metabolic host responses to infection by intracellular bacterial pathogens

PubMed Central

Eisenreich, Wolfgang; Heesemann, Jürgen; Rudel, Thomas; Goebel, Werner

2013-01-01

The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies. PMID:23847769

Detection of hepatitis E virus and other livestock-related pathogens in Iowa streams

USGS Publications Warehouse

Givens, Carrie E.; Kolpin, Dana W.; Borchardt, Mark A.; Duris, Joseph W.; Moorman, Thomas B.; Spencer, Susan K.

2016-01-01

Manure application is a source of pathogens to the environment. Through overland runoff and tile drainage, zoonotic pathogens can contaminate surface water and streambed sediment and could affect both wildlife and human health. This study examined the environmental occurrence of gene markers for livestock-related bacterial, protozoan, and viral pathogens and antibiotic resistance in surface waters within the South Fork Iowa River basin before and after periods of swine manure application on agricultural land. Increased concentrations of indicator bacteria after manure application exceeding Iowa's state bacteria water quality standards suggest that swine manure contributes to diminished water quality and may pose a risk to human health. Additionally, the occurrence of HEV and numerous bacterial pathogen genes for Escherichia coli, Enterococcus spp., Salmonella sp., and Staphylococcus aureus in both manure samples and in corresponding surface water following periods of manure application suggests a potential role for swine in the spreading of zoonotic pathogens to the surrounding environment. During this study, several zoonotic pathogens were detected including Shiga-toxin producing E. coli, Campylobacter jejuni, pathogenic enterococci, and S. aureus; all of which can pose mild to serious health risks to swine, humans, and other wildlife. This research provides the foundational understanding required for future assessment of the risk to environmental health from livestock-related zoonotic pathogen exposures in this region. This information could also be important for maintaining swine herd biosecurity and protecting the health of wildlife near swine facilities.

Comparative genomics of a plant-pathogenic fungus, Pyrenophora tritici-repentis, reveals transduplication and the impact of repeat elements on pathogenicity and population divergence. G3-Genes, Genomes, Genetics.

USDA-ARS?s Scientific Manuscript database

Pyrenophora tritici-repentis is a necrotrophic fungal pathogen and causal agent of tan spot disease of wheat, which has increased significantly over the last few decades. Pathogenicity by this fungus is due to host-selective toxins. These toxins are recognized by their host plant in a genotype-speci...

Insect E-probe Diagnostic Nucleic acid Analysis (EDNA): the application of a novel bioinformatic tool to detection of vectors and pathogens in individual insect and simulated insect trap metagenomes

USDA-ARS?s Scientific Manuscript database

Plant pathogen detection takes many forms. In simple cases, researchers are attempting to detect a known pathogen from a known host utilizing targeted nucleic acid or antigenic assays. However, in more complex scenarios researchers may not know the identity of a pathogen, or they may need to screen ...

Conservation and restoration of forest trees impacted by non-native pathogens: the role of genetics and tree improvement

Treesearch

R.A. Sniezko; L.A. Winn

2017-01-01

North American native tree species in forest ecosystems, as well as managed forests and urban plantings, are being severely impacted by pathogens and insects. The impacts of these pathogens and insects often increase over time, and they are particularly acute for those species affected by non-native pathogens and insects. For restoration of affected tree species or for...

Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks

DTIC Science & Technology

2012-09-21

Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks Paulo Shakarian1*, J. Kenneth Wickiser2 1 Paulo Shakarian...significantly attacked. Citation: Shakarian P, Wickiser JK (2012) Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks...to 00-00-2012 4. TITLE AND SUBTITLE Similar Pathogen Targets in Arabidopsis thaliana and Homo sapiens Protein Networks 5a. CONTRACT NUMBER 5b

Estimating the microbiological risks associated with inland flood events: Bridging theory and models of pathogen transport

PubMed Central

Collender, Philip A.; Cooke, Olivia C.; Bryant, Lee D.; Kjeldsen, Thomas R.; Remais, Justin V.

2017-01-01

Flooding is known to facilitate infectious disease transmission, yet quantitative research on microbiological risks associated with floods has been limited. Pathogen fate and transport models provide a framework to examine interactions between landscape characteristics, hydrology, and waterborne disease risks, but have not been widely developed for flood conditions. We critically examine capabilities of current hydrological models to represent unusual flow paths, non-uniform flow depths, and unsteady flow velocities that accompany flooding. We investigate the theoretical linkages between hydrodynamic processes and spatio-temporally variable suspension and deposition of pathogens from soils and sediments; pathogen dispersion in flow; and concentrations of constituents influencing pathogen transport and persistence. Identifying gaps in knowledge and modeling practice, we propose a research agenda to strengthen microbial fate and transport modeling applied to inland floods: 1) development of models incorporating pathogen discharges from flooded sources (e.g., latrines), effects of transported constituents on pathogen persistence, and supply-limited pathogen transport; 2) studies assessing parameter identifiability and comparing model performance under varying degrees of process representation, in a range of settings; 3) development of remotely sensed datasets to support modeling of vulnerable, data-poor regions; and 4) collaboration between modelers and field-based researchers to expand the collection of useful data in situ. PMID:28757789

Risk-based enteric pathogen reduction targets for non-potable ...

EPA Pesticide Factsheets

This paper presents risk-based enteric pathogen log reduction targets for non-potable and potable uses of a variety of alternative source waters (i.e., locally-collected greywater, roof runoff, and stormwater). A probabilistic Quantitative Microbial Risk Assessment (QMRA) was used to derive the pathogen log10 reduction targets (LRTs) that corresponded with an infection risk of either 10−4 per person per year (ppy) or 10−2 ppy. The QMRA accounted for variation in pathogen concentration and sporadic pathogen occurrence (when data were available) in source waters for reference pathogens in the genera Rotavirus, Mastadenovirus (human adenoviruses), Norovirus, Campylobacter, Salmonella, Giardia and Cryptosporidium. Non-potable uses included indoor use (for toilet flushing and clothes washing) with occasional accidental ingestion of treated non-potable water (or cross-connection with potable water), and unrestricted irrigation for outdoor use. Various exposure scenarios captured the uncertainty from key inputs, i.e., the pathogen concentration in source water; the volume of water ingested; and for the indoor use, the frequency of and the fraction of the population exposed to accidental ingestion. Both potable and non-potable uses required pathogen treatment for the selected waters and the LRT was generally greater for potable use than non-potable indoor use and unrestricted irrigation. The difference in treatment requirements among source waters was driven by the

The Pathogen-Host Interactions database (PHI-base): additions and future developments

PubMed Central

Urban, Martin; Pant, Rashmi; Raghunath, Arathi; Irvine, Alistair G.; Pedro, Helder; Hammond-Kosack, Kim E.

2015-01-01

Rapidly evolving pathogens cause a diverse array of diseases and epidemics that threaten crop yield, food security as well as human, animal and ecosystem health. To combat infection greater comparative knowledge is required on the pathogenic process in multiple species. The Pathogen-Host Interactions database (PHI-base) catalogues experimentally verified pathogenicity, virulence and effector genes from bacterial, fungal and protist pathogens. Mutant phenotypes are associated with gene information. The included pathogens infect a wide range of hosts including humans, animals, plants, insects, fish and other fungi. The current version, PHI-base 3.6, available at http://www.phi-base.org, stores information on 2875 genes, 4102 interactions, 110 host species, 160 pathogenic species (103 plant, 3 fungal and 54 animal infecting species) and 181 diseases drawn from 1243 references. Phenotypic and gene function information has been obtained by manual curation of the peer-reviewed literature. A controlled vocabulary consisting of nine high-level phenotype terms permits comparisons and data analysis across the taxonomic space. PHI-base phenotypes were mapped via their associated gene information to reference genomes available in Ensembl Genomes. Virulence genes and hotspots can be visualized directly in genome browsers. Future plans for PHI-base include development of tools facilitating community-led curation and inclusion of the corresponding host target(s). PMID:25414340

Arabidopsis Heterotrimeric G-Proteins Play a Critical Role in Host and Nonhost Resistance against Pseudomonas syringae Pathogens

PubMed Central

Lee, Seonghee; Rojas, Clemencia M.; Ishiga, Yasuhiro; Pandey, Sona; Mysore, Kirankumar S.

2013-01-01

Heterotrimeric G-proteins have been proposed to be involved in many aspects of plant disease resistance but their precise role in mediating nonhost disease resistance is not well understood. We evaluated the roles of specific subunits of heterotrimeric G-proteins using knock-out mutants of Arabidopsis Gα, Gβ and Gγ subunits in response to host and nonhost Pseudomonas pathogens. Plants lacking functional Gα, Gβ and Gγ1Gγ2 proteins displayed enhanced bacterial growth and disease susceptibility in response to host and nonhost pathogens. Mutations of single Gγ subunits Gγ1, Gγ2 and Gγ3 did not alter bacterial disease resistance. Some specificity of subunit usage was observed when comparing host pathogen versus nonhost pathogen. Overexpression of both Gα and Gβ led to reduced bacterial multiplication of nonhost pathogen P. syringae pv. tabaci whereas overexpression of Gβ, but not of Gα, resulted in reduced bacterial growth of host pathogen P. syringae pv. maculicola, compared to wild-type Col-0. Moreover, the regulation of stomatal aperture by bacterial pathogens was altered in Gα and Gβ mutants but not in any of the single or double Gγ mutants. Taken together, these data substantiate the critical role of heterotrimeric G-proteins in plant innate immunity and stomatal modulation in response to P. syringae. PMID:24349286

Bacterial Pathogens and Community Composition in Advanced Sewage Treatment Systems Revealed by Metagenomics Analysis Based on High-Throughput Sequencing

PubMed Central

Lu, Xin; Zhang, Xu-Xiang; Wang, Zhu; Huang, Kailong; Wang, Yuan; Liang, Weigang; Tan, Yunfei; Liu, Bo; Tang, Junying

2015-01-01

This study used 454 pyrosequencing, Illumina high-throughput sequencing and metagenomic analysis to investigate bacterial pathogens and their potential virulence in a sewage treatment plant (STP) applying both conventional and advanced treatment processes. Pyrosequencing and Illumina sequencing consistently demonstrated that Arcobacter genus occupied over 43.42% of total abundance of potential pathogens in the STP. At species level, potential pathogens Arcobacter butzleri, Aeromonas hydrophila and Klebsiella pneumonia dominated in raw sewage, which was also confirmed by quantitative real time PCR. Illumina sequencing also revealed prevalence of various types of pathogenicity islands and virulence proteins in the STP. Most of the potential pathogens and virulence factors were eliminated in the STP, and the removal efficiency mainly depended on oxidation ditch. Compared with sand filtration, magnetic resin seemed to have higher removals in most of the potential pathogens and virulence factors. However, presence of the residual A. butzleri in the final effluent still deserves more concerns. The findings indicate that sewage acts as an important source of environmental pathogens, but STPs can effectively control their spread in the environment. Joint use of the high-throughput sequencing technologies is considered a reliable method for deep and comprehensive overview of environmental bacterial virulence. PMID:25938416

A Systems Biology Approach to the Coordination of Defensive and Offensive Molecular Mechanisms in the Innate and Adaptive Host–Pathogen Interaction Networks

PubMed Central

Wu, Chia-Chou; Chen, Bor-Sen

2016-01-01

Infected zebrafish coordinates defensive and offensive molecular mechanisms in response to Candida albicans infections, and invasive C. albicans coordinates corresponding molecular mechanisms to interact with the host. However, knowledge of the ensuing infection-activated signaling networks in both host and pathogen and their interspecific crosstalk during the innate and adaptive phases of the infection processes remains incomplete. In the present study, dynamic network modeling, protein interaction databases, and dual transcriptome data from zebrafish and C. albicans during infection were used to infer infection-activated host–pathogen dynamic interaction networks. The consideration of host–pathogen dynamic interaction systems as innate and adaptive loops and subsequent comparisons of inferred innate and adaptive networks indicated previously unrecognized crosstalk between known pathways and suggested roles of immunological memory in the coordination of host defensive and offensive molecular mechanisms to achieve specific and powerful defense against pathogens. Moreover, pathogens enhance intraspecific crosstalk and abrogate host apoptosis to accommodate enhanced host defense mechanisms during the adaptive phase. Accordingly, links between physiological phenomena and changes in the coordination of defensive and offensive molecular mechanisms highlight the importance of host–pathogen molecular interaction networks, and consequent inferences of the host–pathogen relationship could be translated into biomedical applications. PMID:26881892