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Sample records for host cell infection

  1. Dendritic cells in cytomegalovirus infection: viral evasion and host countermeasures.

    PubMed

    Rölle, Alexander; Olweus, Johanna

    2009-05-01

    Human cytomegalovirus (HCMV) is a beta-herpesvirus that infects the majority of the population during early childhood and thereafter establishes life-long latency. Primary infection as well as spontaneous reactivation usually remains asymptomatic in healthy hosts but can, in the context of systemic immunosuppression, result in substantial morbidity and mortality. HCMV counteracts the host immune response by interfering with the recognition of infected cells. A growing body of literature has also suggested that the virus evades the immune system by paralyzing the initiators of antiviral immune responses--the dendritic cells (DCs). In the current review, we discuss the effects of CMV (HCMV and murine CMV) on various DC subsets and the ensuing innate and adaptive immune responses. The impact of HCMV on DCs has mainly been investigated using monocyte-derived DCs, which are rendered functionally impaired by infection. In mouse models, DCs are targets of viral evasion as well, but the complex cross-talk between DCs and natural killer cells has, however, demonstrated an instrumental role for DCs in the control and clearance of viral infection. Fewer studies address the role of peripheral blood DC subsets, plasmacytoid DCs and CD11c+ myeloid DCs in the response against HCMV. These DCs, rather than being paralyzed by HCMV, are largely resistant to infection, mount a vigorous first-line defense and induce T-cell responses to the virus. This possibly provides a partial explanation for an intriguing conundrum: the highly efficient control of viral infection and reactivation in immunocompetent hosts in spite of multi-layered viral evasion mechanisms.

  2. Th9 Cells Drive Host Immunity against Gastrointestinal Worm Infection.

    PubMed

    Licona-Limón, Paula; Henao-Mejia, Jorge; Temann, Angela U; Gagliani, Nicola; Licona-Limón, Ileana; Ishigame, Harumichi; Hao, Liming; Herbert, De'broski R; Flavell, Richard A

    2013-10-17

    Type 2 inflammatory cytokines, including interleukin-4 (IL-4), IL-5, IL-9, and IL-13, drive the characteristic features of immunity against parasitic worms and allergens. Whether IL-9 serves an essential role in the initiation of host-protective responses is controversial, and the importance of IL-9- versus IL-4-producing CD4⁺ effector T cells in type 2 immunity is incompletely defined. Herein, we generated IL-9-deficient and IL-9-fluorescent reporter mice that demonstrated an essential role for this cytokine in the early type 2 immunity against Nippostrongylus brasiliensis. Whereas T helper 9 (Th9) cells and type 2 innate lymphoid cells (ILC2s) were major sources of infection-induced IL-9 production, the adoptive transfer of Th9 cells, but not Th2 cells, caused rapid worm expulsion, marked basophilia, and increased mast cell numbers in Rag2-deficient hosts. Taken together, our data show a critical and nonredundant role for Th9 cells and IL-9 in host-protective type 2 immunity against parasitic worm infection.

  3. Infection Strategies of Intestinal Parasite Pathogens and Host Cell Responses.

    PubMed

    Di Genova, Bruno M; Tonelli, Renata R

    2016-01-01

    Giardia lamblia, Cryptosporidium sp., and Entamoeba histolytica are important pathogenic intestinal parasites and are amongst the leading causes worldwide of diarrheal illness in humans. Diseases caused by these organisms, giardiasis, cryptosporidiosis, and amoebiasis, respectively, are characterized by self-limited diarrhea but can evolve to long-term complications. The cellular and molecular mechanisms underlying the pathogenesis of diarrhea associated with these three pathogens are being unraveled, with knowledge of both the strategies explored by the parasites to establish infection and the methods evolved by hosts to avoid it. Special attention is being given to molecules participating in parasite-host interaction and in the mechanisms implicated in the diseases' pathophysiologic processes. This review focuses on cell mechanisms that are modulated during infection, including gene transcription, cytoskeleton rearrangements, signal transduction pathways, and cell death. PMID:26973630

  4. Infection Strategies of Intestinal Parasite Pathogens and Host Cell Responses

    PubMed Central

    Di Genova, Bruno M.; Tonelli, Renata R.

    2016-01-01

    Giardia lamblia, Cryptosporidium sp., and Entamoeba histolytica are important pathogenic intestinal parasites and are amongst the leading causes worldwide of diarrheal illness in humans. Diseases caused by these organisms, giardiasis, cryptosporidiosis, and amoebiasis, respectively, are characterized by self-limited diarrhea but can evolve to long-term complications. The cellular and molecular mechanisms underlying the pathogenesis of diarrhea associated with these three pathogens are being unraveled, with knowledge of both the strategies explored by the parasites to establish infection and the methods evolved by hosts to avoid it. Special attention is being given to molecules participating in parasite–host interaction and in the mechanisms implicated in the diseases’ pathophysiologic processes. This review focuses on cell mechanisms that are modulated during infection, including gene transcription, cytoskeleton rearrangements, signal transduction pathways, and cell death. PMID:26973630

  5. Infection Strategies of Intestinal Parasite Pathogens and Host Cell Responses.

    PubMed

    Di Genova, Bruno M; Tonelli, Renata R

    2016-01-01

    Giardia lamblia, Cryptosporidium sp., and Entamoeba histolytica are important pathogenic intestinal parasites and are amongst the leading causes worldwide of diarrheal illness in humans. Diseases caused by these organisms, giardiasis, cryptosporidiosis, and amoebiasis, respectively, are characterized by self-limited diarrhea but can evolve to long-term complications. The cellular and molecular mechanisms underlying the pathogenesis of diarrhea associated with these three pathogens are being unraveled, with knowledge of both the strategies explored by the parasites to establish infection and the methods evolved by hosts to avoid it. Special attention is being given to molecules participating in parasite-host interaction and in the mechanisms implicated in the diseases' pathophysiologic processes. This review focuses on cell mechanisms that are modulated during infection, including gene transcription, cytoskeleton rearrangements, signal transduction pathways, and cell death.

  6. Listeria monocytogenes induces host DNA damage and delays the host cell cycle to promote infection

    PubMed Central

    Leitão, Elsa; Costa, Ana Catarina; Brito, Cláudia; Costa, Lionel; Pombinho, Rita; Cabanes, Didier; Sousa, Sandra

    2014-01-01

    Listeria monocytogenes (Lm) is a human intracellular pathogen widely used to uncover the mechanisms evolved by pathogens to establish infection. However, its capacity to perturb the host cell cycle was never reported. We show that Lm infection affects the host cell cycle progression, increasing its overall duration but allowing consecutive rounds of division. A complete Lm infectious cycle induces a S-phase delay accompanied by a slower rate of DNA synthesis and increased levels of host DNA strand breaks. Additionally, DNA damage/replication checkpoint responses are triggered in an Lm dose-dependent manner through the phosphorylation of DNA-PK, H2A.X, and CDC25A and independently from ATM/ATR. While host DNA damage induced exogenously favors Lm dissemination, the override of checkpoint pathways limits infection. We propose that host DNA replication disturbed by Lm infection culminates in DNA strand breaks, triggering DNA damage/replication responses, and ensuring a cell cycle delay that favors Lm propagation. PMID:24552813

  7. Host Cell Factors as Antiviral Targets in Arenavirus Infection

    PubMed Central

    Linero, Florencia N.; Sepúlveda, Claudia S.; Giovannoni, Federico; Castilla, Viviana; García, Cybele C.; Scolaro, Luis A.; Damonte, Elsa B.

    2012-01-01

    Among the members of the Arenaviridae family, Lassa virus and Junin virus generate periodic annual outbreaks of severe human hemorrhagic fever (HF) in endemic areas of West Africa and Argentina, respectively. Given the human health threat that arenaviruses represent and the lack of a specific and safe chemotherapy, the search for effective antiviral compounds is a continuous demanding effort. Since diverse host cell pathways and enzymes are used by RNA viruses to fulfill their replicative cycle, the targeting of a host process has turned an attractive antiviral approach in the last years for many unrelated virus types. This strategy has the additional benefit to reduce the serious challenge for therapy of RNA viruses to escape from drug effects through selection of resistant variants triggered by their high mutation rate. This article focuses on novel strategies to identify inhibitors for arenavirus therapy, analyzing the potential for antiviral developments of diverse host factors essential for virus infection. PMID:23170173

  8. Analysis of Host Gene Expression Profile in HIV-1 and HIV-2 Infected T-Cells.

    PubMed

    Devadas, Krishnakumar; Biswas, Santanu; Haleyurgirisetty, Mohan; Wood, Owen; Ragupathy, Viswanath; Lee, Sherwin; Hewlett, Indira

    2016-01-01

    HIV replication is closely regulated by a complex pathway of host factors, many of them being determinants of cell tropism and host susceptibility to HIV infection. These host factors are known to exert a positive or negative influence on the replication of the two major types of HIV, HIV-1 and HIV-2, thereby modulating virus infectivity, host response to infection and ultimately disease progression profiles characteristic of these two types. Understanding the differential regulation of host cellular factors in response to HIV-1 and HIV-2 infections will help us to understand the apparent differences in rates of disease progression and pathogenesis. This knowledge would aid in the discovery of new biomarkers that may serve as novel targets for therapy and diagnosis. The objective of this study was to determine the differential expression of host genes in response to HIV-1/HIV-2 infection. To achieve this, we analyzed the effects of HIV-1 (MN) and HIV-2 (ROD) infection on the expression of host factors in PBMC at the RNA level using the Agilent Whole Human Genome Oligo Microarray. Differentially expressed genes were identified and their biological functions determined. Host gene expression profiles were significantly changed. Gene expression profiling analysis identified a subset of differentially expressed genes in HIV-1 and HIV-2 infected cells. Genes involved in cellular metabolism, apoptosis, immune cell proliferation and activation, cytokines, chemokines, and transcription factors were differentially expressed in HIV-1 infected cells. Relatively few genes were differentially expressed in cells infected with HIV-2.

  9. Analysis of Host Gene Expression Profile in HIV-1 and HIV-2 Infected T-Cells

    PubMed Central

    Devadas, Krishnakumar; Biswas, Santanu; Haleyurgirisetty, Mohan; Wood, Owen; Ragupathy, Viswanath; Lee, Sherwin; Hewlett, Indira

    2016-01-01

    HIV replication is closely regulated by a complex pathway of host factors, many of them being determinants of cell tropism and host susceptibility to HIV infection. These host factors are known to exert a positive or negative influence on the replication of the two major types of HIV, HIV-1 and HIV-2, thereby modulating virus infectivity, host response to infection and ultimately disease progression profiles characteristic of these two types. Understanding the differential regulation of host cellular factors in response to HIV-1 and HIV-2 infections will help us to understand the apparent differences in rates of disease progression and pathogenesis. This knowledge would aid in the discovery of new biomarkers that may serve as novel targets for therapy and diagnosis. The objective of this study was to determine the differential expression of host genes in response to HIV-1/HIV-2 infection. To achieve this, we analyzed the effects of HIV-1 (MN) and HIV-2 (ROD) infection on the expression of host factors in PBMC at the RNA level using the Agilent Whole Human Genome Oligo Microarray. Differentially expressed genes were identified and their biological functions determined. Host gene expression profiles were significantly changed. Gene expression profiling analysis identified a subset of differentially expressed genes in HIV-1 and HIV-2 infected cells. Genes involved in cellular metabolism, apoptosis, immune cell proliferation and activation, cytokines, chemokines, and transcription factors were differentially expressed in HIV-1 infected cells. Relatively few genes were differentially expressed in cells infected with HIV-2. PMID:26821323

  10. Exosomes Secreted by Toxoplasma gondii-Infected L6 Cells: Their Effects on Host Cell Proliferation and Cell Cycle Changes

    PubMed Central

    Kim, Min Jae; Jung, Bong-Kwang; Cho, Jaeeun; Song, Hyemi; Pyo, Kyung-Ho; Lee, Ji Min; Kim, Min-Kyung; Chai, Jong-Yil

    2016-01-01

    Toxoplasma gondii infection induces alteration of the host cell cycle and cell proliferation. These changes are not only seen in directly invaded host cells but also in neighboring cells. We tried to identify whether this alteration can be mediated by exosomes secreted by T. gondii-infected host cells. L6 cells, a rat myoblast cell line, and RH strain of T. gondii were selected for this study. L6 cells were infected with or without T. gondii to isolate exosomes. The cellular growth patterns were identified by cell counting with trypan blue under confocal microscopy, and cell cycle changes were investigated by flow cytometry. L6 cells infected with T. gondii showed decreased proliferation compared to uninfected L6 cells and revealed a tendency to stay at S or G2/M cell phase. The treatment of exosomes isolated from T. gondii-infected cells showed attenuation of cell proliferation and slight enhancement of S phase in L6 cells. The cell cycle alteration was not as obvious as reduction of the cell proliferation by the exosome treatment. These changes were transient and disappeared at 48 hr after the exosome treatment. Microarray analysis and web-based tools indicated that various exosomal miRNAs were crucial for the regulation of target genes related to cell proliferation. Collectively, our study demonstrated that the exosomes originating from T. gondii could change the host cell proliferation and alter the host cell cycle. PMID:27180572

  11. The Effect of Enterohemorrhagic E. coli Infection on the Cell Mechanics of Host Cells

    PubMed Central

    Chen, Yin-Quan; Su, Pin-Tzu; Chen, Yu-Hsuan; Wei, Ming-Tzo; Huang, Chien-Hsiu; Osterday, Kathryn; del Álamo, Juan C.; Syu, Wan-Jr; Chiou, Arthur

    2014-01-01

    Enterohaemorrhagic E. coli (EHEC) is a type of human pathogenic bacteria. The main virulence characteristics of EHEC include the formation of attaching and effacing lesions (A/E lesions) and the production of one or more Shiga-like toxins, which may induce human uremic complications. When EHEC infects host cells, it releases translocated intimin receptor (Tir) and effector proteins inside the host cells, inducing the rearrangement and accumulation of the F-actin cytoskeleton, a phenotype leading to the formation of pedestals in the apical cell surface, and the growth of stress fibers at the base of the cells. To examine the effect of EHEC infection on cell mechanics, we carried out a series of experiments to examine HeLa cells with and without EHEC infection to quantify the changes in (1) focal adhesion area, visualized by anti-vinculin staining; (2) the distribution and orientation of stress fibers; and (3) the intracellular viscoelasticity, via directional video particle tracking microrheology. Our results indicated that in EHEC-infected HeLa cells, the focal adhesion area increased and the actin stress fibers became thicker and more aligned. The cytoskeletal reorganization induced by EHEC infection mediated a dramatic increase in the cytoplasmic elastic shear modulus of the infected cells, and a transition in the viscoelastic behavior of the cells from viscous-like to elastic-like. These changes in mechanobiological characteristics might modulate the attachments between EHEC and the host cell to withstand exfoliation, and between the host cell and the extracellular matrix, and might also alter epithelial integrity. PMID:25369259

  12. A Systems Survey of Progressive Host-Cell Reorganization during Rotavirus Infection.

    PubMed

    Green, Victoria A; Pelkmans, Lucas

    2016-07-13

    Pathogen invasion is often accompanied by widespread alterations in cellular physiology, which reflects the hijacking of host factors and processes for pathogen entry and replication. Although genetic perturbation screens have revealed the complexity of host factors involved for numerous pathogens, it has remained challenging to temporally define the progression of events in host cell reorganization during infection. We combine high-confidence genome-scale RNAi screening of host factors required for rotavirus infection in human intestinal cells with an innovative approach to infer the trajectory of virus infection from fixed cell populations. This approach reveals a comprehensive network of host cellular processes involved in rotavirus infection and implicates AMPK in initiating the development of a rotavirus-permissive environment. Our work provides a powerful approach that can be generalized to order complex host cellular requirements along a trajectory of cellular reorganization during pathogen invasion.

  13. A Systems Survey of Progressive Host-Cell Reorganization during Rotavirus Infection.

    PubMed

    Green, Victoria A; Pelkmans, Lucas

    2016-07-13

    Pathogen invasion is often accompanied by widespread alterations in cellular physiology, which reflects the hijacking of host factors and processes for pathogen entry and replication. Although genetic perturbation screens have revealed the complexity of host factors involved for numerous pathogens, it has remained challenging to temporally define the progression of events in host cell reorganization during infection. We combine high-confidence genome-scale RNAi screening of host factors required for rotavirus infection in human intestinal cells with an innovative approach to infer the trajectory of virus infection from fixed cell populations. This approach reveals a comprehensive network of host cellular processes involved in rotavirus infection and implicates AMPK in initiating the development of a rotavirus-permissive environment. Our work provides a powerful approach that can be generalized to order complex host cellular requirements along a trajectory of cellular reorganization during pathogen invasion. PMID:27414499

  14. HIV-host interactome revealed directly from infected cells.

    PubMed

    Luo, Yang; Jacobs, Erica Y; Greco, Todd M; Mohammed, Kevin D; Tong, Tommy; Keegan, Sarah; Binley, James M; Cristea, Ileana M; Fenyö, David; Rout, Michael P; Chait, Brian T; Muesing, Mark A

    2016-01-01

    Although genetically compact, HIV-1 commandeers vast arrays of cellular machinery to sustain and protect it during cycles of viral outgrowth. Transposon-mediated saturation linker scanning mutagenesis was used to isolate fully replication-competent viruses harbouring a potent foreign epitope tag. Using these viral isolates, we performed differential isotopic labelling and affinity-capture mass spectrometric analyses on samples obtained from cultures of human lymphocytes to classify the vicinal interactomes of the viral Env and Vif proteins as they occur during natural infection. Importantly, interacting proteins were recovered without bias, regardless of their potential for positive, negative or neutral impact on viral replication. We identified specific host associations made with trimerized Env during its biosynthesis, at virological synapses, with innate immune effectors (such as HLA-E) and with certain cellular signalling pathways (for example, Notch1). We also defined Vif associations with host proteins involved in the control of nuclear transcription and nucleoside biosynthesis as well as those interacting stably or transiently with the cytoplasmic protein degradation apparatus. Our approach is broadly applicable to elucidating pathogen-host interactomes, providing high-certainty identification of interactors by their direct access during cycling infection. Understanding the pathophysiological consequences of these associations is likely to provide strategic targets for antiviral intervention. PMID:27572969

  15. HIV–host interactome revealed directly from infected cells

    PubMed Central

    Luo, Yang; Jacobs, Erica Y.; Greco, Todd M.; Mohammed, Kevin D.; Tong, Tommy; Keegan, Sarah; Binley, James M.; Cristea, Ileana M.; Fenyö, David; Rout, Michael P.; Chait, Brian T.; Muesing, Mark A.

    2016-01-01

    Although genetically compact, HIV-1 commandeers vast arrays of cellular machinery to sustain and protect it during cycles of viral outgrowth. Transposon-mediated saturation linker scanning mutagenesis was used to isolate fully replication-competent viruses harbouring a potent foreign epitope tag. Using these viral isolates, we performed differential isotopic labelling and affinity-capture mass spectrometric analyses on samples obtained from cultures of human lymphocytes to classify the vicinal interactomes of the viral Env and Vif proteins as they occur during natural infection. Importantly, interacting proteins were recovered without bias, regardless of their potential for positive, negative or neutral impact on viral replication. We identified specific host associations made with trimerized Env during its biosynthesis, at virological synapses, with innate immune effectors (such as HLA-E) and with certain cellular signalling pathways (for example, Notch1). We also defined Vif associations with host proteins involved in the control of nuclear transcription and nucleoside biosynthesis as well as those interacting stably or transiently with the cytoplasmic protein degradation apparatus. Our approach is broadly applicable to elucidating pathogen–host interactomes, providing high-certainty identification of interactors by their direct access during cycling infection. Understanding the pathophysiological consequences of these associations is likely to provide strategic targets for antiviral intervention. PMID:27375898

  16. Immune regulation and evasion of Mammalian host cell immunity during viral infection.

    PubMed

    Pratheek, B M; Saha, Soham; Maiti, Prasanta K; Chattopadhyay, Soma; Chattopadhyay, Subhasis

    2013-06-01

    The mammalian host immune system has wide array of defence mechanisms against viral infections. Depending on host immunity and the extent of viral persistence, either the host immune cells might clear/restrict the viral load and disease progression or the virus might evade host immunity by down regulating host immune effector response(s). Viral antigen processing and presentation in the host cells through major histocompatibility complex (MHC) elicit subsequent anti-viral effector T cell response(s). However, modulation of such response(s) might generate one of the important viral immune evasion strategies. Viral peptides are mostly generated by proteolytic cleavage in the cytosol of the infected host cells. CD8(+) T lymphocytes play critical role in the detection of viral infection by recognizing these peptides displayed at the plasma membrane by MHC-I molecules. The present review summarises the current knowledge on the regulation of mammalian host innate and adaptive immune components, which are operative in defence mechanisms against viral infections and the variety of strategies that viruses have evolved to escape host cell immunity. The understanding of viral immune evasion strategies is important for designing anti-viral immunotherapies.

  17. Evidence that the epidermal growth factor receptor on host cells confers reovirus infection efficiency.

    PubMed

    Strong, J E; Tang, D; Lee, P W

    1993-11-01

    Reovirus binds to multiple sialoglycoproteins on the host cell surface. In an attempt to probe additional specific determinants that dictate host cell susceptibility to reovirus infection, we found that two mouse cell lines (NR6 and B82) previously shown to express no endogenous epidermal growth factor (EGF) receptors were relatively resistant to reovirus infection, whereas the same cell lines transfected with the gene encoding the EGF receptor manifested significantly higher susceptibility as determined by induction of cytopathic effects, viral protein synthesis, and plaque titration. This enhancement of infection efficiency requires a functional EGF receptor since it was not observed in cells expressing a mutated (kinase-inactive) EGF receptor. The observed difference in infection efficiency is not due to differences in virus binding or internalization. These studies suggest that the reovirus infection process is closely coupled to the EGF receptor-mediated cell signal transduction pathway.

  18. Fierce Competition between Toxoplasma and Chlamydia for Host Cell Structures in Dually Infected Cells

    PubMed Central

    Romano, Julia D.; de Beaumont, Catherine; Carrasco, Jose A.; Ehrenman, Karen; Bavoil, Patrik M.

    2013-01-01

    The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients. PMID:23243063

  19. Fierce competition between Toxoplasma and Chlamydia for host cell structures in dually infected cells.

    PubMed

    Romano, Julia D; de Beaumont, Catherine; Carrasco, Jose A; Ehrenman, Karen; Bavoil, Patrik M; Coppens, Isabelle

    2013-02-01

    The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients.

  20. Proteomic analysis of host responses in HepG2 cells during dengue virus infection.

    PubMed

    Pattanakitsakul, Sa-Nga; Rungrojcharoenkit, Kamonthip; Kanlaya, Rattiyaporn; Sinchaikul, Supachok; Noisakran, Sansanee; Chen, Shui-Tein; Malasit, Prida; Thongboonkerd, Visith

    2007-12-01

    Dengue virus infection remains a public health problem worldwide. However, its pathogenic mechanisms and pathophysiology are still poorly understood. We performed proteomic analysis to evaluate early host responses (as indicated by altered proteins) in human target cells during dengue virus infection. HepG2 cells were infected with dengue virus serotype 2 (DEN-2) at multiplicity of infection (MOI) of 0.1, 0.5, and 1.0. Quantitative analyses of DEN-2 infection and cell death at 12, 24, and 48 h postinfection showed that the MOI of 1.0 with 24 h postinfection duration was the optimal condition to evaluate early host responses, as this condition provided the high %Infection ( approximately 80%), while %Cell death ( approximately 20%) was comparable to that of the mock-control cells. Proteins derived from the mock-control and DEN-2-infected cells were resolved by 2-D PAGE ( n = 5 gels for each group) and visualized by SYPRO Ruby stain. Quantitative intensity analysis revealed 17 differentially expressed proteins, which were successfully identified by peptide mass fingerprinting. Most of these altered proteins were the key factors involved in transcription and translation processes. Further functional study on these altered proteins may lead to better understanding of the pathogenic mechanisms and host responses to dengue virus infection, and also to the identification of new therapeutic targets for dengue virus infection.

  1. Influenza A Virus Dysregulates Host Histone Deacetylase 1 That Inhibits Viral Infection in Lung Epithelial Cells

    PubMed Central

    Nagesh, Prashanth Thevkar

    2016-01-01

    ABSTRACT Viruses dysregulate the host factors that inhibit virus infection. Here, we demonstrate that human enzyme, histone deacetylase 1 (HDAC1) is a new class of host factor that inhibits influenza A virus (IAV) infection, and IAV dysregulates HDAC1 to efficiently replicate in epithelial cells. A time-dependent decrease in HDAC1 polypeptide level was observed in IAV-infected cells, reducing to <50% by 24 h of infection. A further depletion (97%) of HDAC1 expression by RNA interference increased the IAV growth kinetics, increasing it by >3-fold by 24 h and by >6-fold by 48 h of infection. Conversely, overexpression of HDAC1 decreased the IAV infection by >2-fold. Likewise, a time-dependent decrease in HDAC1 activity, albeit with slightly different kinetics to HDAC1 polypeptide reduction, was observed in infected cells. Nevertheless, a further inhibition of deacetylase activity increased IAV infection in a dose-dependent manner. HDAC1 is an important host deacetylase and, in addition to its role as a transcription repressor, HDAC1 has been lately described as a coactivator of type I interferon response. Consistent with this property, we found that inhibition of deacetylase activity either decreased or abolished the phosphorylation of signal transducer and activator of transcription I (STAT1) and expression of interferon-stimulated genes, IFITM3, ISG15, and viperin in IAV-infected cells. Furthermore, the knockdown of HDAC1 expression in infected cells decreased viperin expression by 58% and, conversely, the overexpression of HDAC1 increased it by 55%, indicating that HDAC1 is a component of IAV-induced host type I interferon antiviral response. IMPORTANCE Influenza A virus (IAV) continues to significantly impact global public health by causing regular seasonal epidemics, occasional pandemics, and zoonotic outbreaks. IAV is among the successful human viral pathogens that has evolved various strategies to evade host defenses, prevent the development of a universal

  2. Perturbation of Host Cell Cytoskeleton by Cranberry Proanthocyanidins and Their Effect on Enteric Infections

    PubMed Central

    Harmidy, Kevin; Tufenkji, Nathalie; Gruenheid, Samantha

    2011-01-01

    Cranberry-derived compounds, including a fraction known as proanthocyanidins (PACs) exhibit anti-microbial, anti-infective, and anti-adhesive properties against a number of disease-causing organisms. In this study, the effect of cranberry proanthocyanidins (CPACs) on the infection of epithelial cells by two enteric bacterial pathogens, enteropathogenic Escherichia coli (EPEC) and Salmonella Typhimurium was investigated. Immunofluorescence data showed that actin pedestal formation, required for infection by enteropathogenic Escherichia coli (EPEC), was disrupted in the presence of CPACs. In addition, invasion of HeLa cells by Salmonella Typhimurium was significantly reduced, as verified by gentamicin protection assay and immunofluorescence. CPACs had no effect on bacterial growth, nor any detectable effect on the production of bacterial effector proteins of the type III secretion system. Furthermore, CPACs did not affect the viability of host cells. Interestingly, we found that CPACs had a potent and dose-dependent effect on the host cell cytoskeleton that was evident even in uninfected cells. CPACs inhibited the phagocytosis of inert particles by a macrophage cell line, providing further evidence that actin-mediated host cell functions are disrupted in the presence of cranberry CPACs. Thus, although CPAC treatment inhibited Salmonella invasion and EPEC pedestal formation, our results suggest that this is likely primarily because of the perturbation of the host cell cytoskeleton by CPACs rather than an effect on bacterial virulence itself. These findings have significant implications for the interpretation of experiments on the effects of CPACs on bacteria-host cell interactions. PMID:22076143

  3. Foxp3+ regulatory T cells, immune stimulation and host defence against infection

    PubMed Central

    Rowe, Jared H; Ertelt, James M; Way, Sing Sing

    2012-01-01

    The immune system is intricately regulated allowing potent effectors to expand and become rapidly mobilized after infection, while simultaneously silencing potentially detrimental responses that averts immune-mediated damage to host tissues. This relies in large part on the delicate interplay between immune suppressive regulatory CD4+ T (Treg) cells and immune effectors that without active suppression by Treg cells cause systemic and organ-specific autoimmunity. Although these beneficial roles have been classically described as counterbalanced by impaired host defence against infection, newfound protective roles for Treg cells against specific viral pathogens (e.g. herpes simplex virus 2, lymphocytic choriomeningitis virus, West Nile virus) have been uncovered using transgenic mice that allow in vivo Treg-cell ablation based on Foxp3 expression. In turn, Foxp3+ Treg cells also provide protection against some parasitic (Plasmodium sp., Toxoplasma gondii) and fungal (Candida albicans) pathogens. By contrast, for bacterial and mycobacterial infections (e.g. Listeria monocytogenes, Salmonella enterica, Mycobacterium tuberculosis), experimental manipulation of Foxp3+ cells continues to indicate detrimental roles for Treg cells in host defence. This variance is probably related to functional plasticity in Treg cell suppression that shifts discordantly following infection with different types of pathogens. Furthermore, the efficiency whereby Treg cells silence immune activation coupled with the plasticity in Foxp3+ cell activity suggest that overriding Treg-mediated suppression represents a prerequisite ‘signal zero’ that together with other stimulation signals [T-cell receptor (signal 1), co-stimulation (signal 2), inflammatory cytokines (signal 3)] are essential for T-cell activation in vivo. Herein, the importance of Foxp3+ Treg cells in host defence against infection, and the significance of infection-induced shifts in Treg-cell suppression are summarized. PMID

  4. Coxiella burnetii Nine Mile II proteins modulate gene expression of monocytic host cells during infection

    PubMed Central

    2010-01-01

    Background Coxiella burnetii is an intracellular bacterial pathogen that causes acute and chronic disease in humans. Bacterial replication occurs within enlarged parasitophorous vacuoles (PV) of eukaryotic cells, the biogenesis and maintenance of which is dependent on C. burnetii protein synthesis. These observations suggest that C. burnetii actively subverts host cell processes, however little is known about the cellular biology mechanisms manipulated by the pathogen during infection. Here, we examined host cell gene expression changes specifically induced by C. burnetii proteins during infection. Results We have identified 36 host cell genes that are specifically regulated when de novo C. burnetii protein synthesis occurs during infection using comparative microarray analysis. Two parallel sets of infected and uninfected THP-1 cells were grown for 48 h followed by the addition of chloramphenicol (CAM) to 10 μg/ml in one set. Total RNA was harvested at 72 hpi from all conditions, and microarrays performed using Phalanx Human OneArray™ slides. A total of 784 (mock treated) and 901 (CAM treated) THP-1 genes were up or down regulated ≥2 fold in the C. burnetii infected vs. uninfected cell sets, respectively. Comparisons between the complementary data sets (using >0 fold), eliminated the common gene expression changes. A stringent comparison (≥2 fold) between the separate microarrays revealed 36 host cell genes modulated by C. burnetii protein synthesis. Ontological analysis of these genes identified the innate immune response, cell death and proliferation, vesicle trafficking and development, lipid homeostasis, and cytoskeletal organization as predominant cellular functions modulated by C. burnetii protein synthesis. Conclusions Collectively, these data indicate that C. burnetii proteins actively regulate the expression of specific host cell genes and pathways. This is in addition to host cell genes that respond to the presence of the pathogen whether or not

  5. Human borna disease virus infection impacts host proteome and histone lysine acetylation in human oligodendroglia cells

    SciTech Connect

    Liu, Xia; Zhao, Libo; Yang, Yongtao; Bode, Liv; Huang, Hua; Liu, Chengyu; Huang, Rongzhong; Zhang, Liang; and others

    2014-09-15

    Background: Borna disease virus (BDV) replicates in the nucleus and establishes persistent infections in mammalian hosts. A human BDV strain was used to address the first time, how BDV infection impacts the proteome and histone lysine acetylation (Kac) of human oligodendroglial (OL) cells, thus allowing a better understanding of infection-driven pathophysiology in vitro. Methods: Proteome and histone lysine acetylation were profiled through stable isotope labeling for cell culture (SILAC)-based quantitative proteomics. The quantifiable proteome was annotated using bioinformatics. Histone acetylation changes were validated by biochemistry assays. Results: Post BDV infection, 4383 quantifiable differential proteins were identified and functionally annotated to metabolism pathways, immune response, DNA replication, DNA repair, and transcriptional regulation. Sixteen of the thirty identified Kac sites in core histones presented altered acetylation levels post infection. Conclusions: BDV infection using a human strain impacted the whole proteome and histone lysine acetylation in OL cells. - Highlights: • A human strain of BDV (BDV Hu-H1) was used to infect human oligodendroglial cells (OL cells). • This study is the first to reveal the host proteomic and histone Kac profiles in BDV-infected OL cells. • BDV infection affected the expression of many transcription factors and several HATs and HDACs.

  6. Profiling of Host Cell Response to Successive Canine Parvovirus Infection Based on Kinetic Proteomic Change Identification.

    PubMed

    Zhao, Hang; Cheng, Yuening; Wang, Jianke; Lin, Peng; Yi, Li; Sun, Yaru; Ren, Jingqiang; Tong, Mingwei; Cao, Zhigang; Li, Jiawei; Deng, Jinliang; Cheng, Shipeng

    2016-01-01

    Canine parvovirus (CPV) reproduces by co-opting the resources of host cells, inevitably causing cytotoxic effects to the host cells. Feline kidney F81 cells are sensitive to CPV infection and show disparate growing statuses at different time points post-infection. This study analysed the response of F81 cells to CPV infection at successive infection time points by iTRAQ-based quantitative proteomics. Differentially expressed proteins (DEPs) during 60 h of infection and at selected time points post-infection were identified by an analysis of variance test and a two-tailed unpaired t test, respectively. DEPs with similar quantitative changes were clustered by hierarchical clustering and analysed by gene ontology enrichment, revealing that 12 h and 60 h post-infection were the optimal times to analyse the autonomous parvovirus replication and apoptosis processes, respectively. Using the Metacore(TM) database, 29 DEPs were enriched in a network involved in p53 regulation. Besides, a significantly enriched pathway suggests that the CPV-induced cytopathic effect was probably due to the deficiency of functional CFTR caused by CPV infection. This study uncovered the systemic changes in key cellular factors involved in CPV infection and help to understand the molecular mechanisms of the anti-cancer activity of CPV and the cytopathic effects induced by CPV infection. PMID:27406444

  7. Profiling of Host Cell Response to Successive Canine Parvovirus Infection Based on Kinetic Proteomic Change Identification

    PubMed Central

    Zhao, Hang; Cheng, Yuening; Wang, Jianke; Lin, Peng; Yi, Li; Sun, Yaru; Ren, Jingqiang; Tong, Mingwei; Cao, Zhigang; Li, Jiawei; Deng, Jinliang; Cheng, Shipeng

    2016-01-01

    Canine parvovirus (CPV) reproduces by co-opting the resources of host cells, inevitably causing cytotoxic effects to the host cells. Feline kidney F81 cells are sensitive to CPV infection and show disparate growing statuses at different time points post-infection. This study analysed the response of F81 cells to CPV infection at successive infection time points by iTRAQ-based quantitative proteomics. Differentially expressed proteins (DEPs) during 60 h of infection and at selected time points post-infection were identified by an analysis of variance test and a two-tailed unpaired t test, respectively. DEPs with similar quantitative changes were clustered by hierarchical clustering and analysed by gene ontology enrichment, revealing that 12 h and 60 h post-infection were the optimal times to analyse the autonomous parvovirus replication and apoptosis processes, respectively. Using the MetacoreTM database, 29 DEPs were enriched in a network involved in p53 regulation. Besides, a significantly enriched pathway suggests that the CPV-induced cytopathic effect was probably due to the deficiency of functional CFTR caused by CPV infection. This study uncovered the systemic changes in key cellular factors involved in CPV infection and help to understand the molecular mechanisms of the anti-cancer activity of CPV and the cytopathic effects induced by CPV infection. PMID:27406444

  8. Profiling of Host Cell Response to Successive Canine Parvovirus Infection Based on Kinetic Proteomic Change Identification.

    PubMed

    Zhao, Hang; Cheng, Yuening; Wang, Jianke; Lin, Peng; Yi, Li; Sun, Yaru; Ren, Jingqiang; Tong, Mingwei; Cao, Zhigang; Li, Jiawei; Deng, Jinliang; Cheng, Shipeng

    2016-01-01

    Canine parvovirus (CPV) reproduces by co-opting the resources of host cells, inevitably causing cytotoxic effects to the host cells. Feline kidney F81 cells are sensitive to CPV infection and show disparate growing statuses at different time points post-infection. This study analysed the response of F81 cells to CPV infection at successive infection time points by iTRAQ-based quantitative proteomics. Differentially expressed proteins (DEPs) during 60 h of infection and at selected time points post-infection were identified by an analysis of variance test and a two-tailed unpaired t test, respectively. DEPs with similar quantitative changes were clustered by hierarchical clustering and analysed by gene ontology enrichment, revealing that 12 h and 60 h post-infection were the optimal times to analyse the autonomous parvovirus replication and apoptosis processes, respectively. Using the Metacore(TM) database, 29 DEPs were enriched in a network involved in p53 regulation. Besides, a significantly enriched pathway suggests that the CPV-induced cytopathic effect was probably due to the deficiency of functional CFTR caused by CPV infection. This study uncovered the systemic changes in key cellular factors involved in CPV infection and help to understand the molecular mechanisms of the anti-cancer activity of CPV and the cytopathic effects induced by CPV infection.

  9. Virus-host coevolution in a persistently coxsackievirus B3-infected cardiomyocyte cell line.

    PubMed

    Pinkert, Sandra; Klingel, Karin; Lindig, Vanessa; Dörner, Andrea; Zeichhardt, Heinz; Spiller, O Brad; Fechner, Henry

    2011-12-01

    Coevolution of virus and host is a process that emerges in persistent virus infections. Here we studied the coevolutionary development of coxsackievirus B3 (CVB3) and cardiac myocytes representing the major target cells of CVB3 in the heart in a newly established persistently CVB3-infected murine cardiac myocyte cell line, HL-1(CVB3). CVB3 persistence in HL-1(CVB3) cells represented a typical carrier-state infection with high levels (10(6) to 10(8) PFU/ml) of infectious virus produced from only a small proportion (approximately 10%) of infected cells. CVB3 persistence was characterized by the evolution of a CVB3 variant (CVB3-HL1) that displayed strongly increased cytotoxicity in the naive HL-1 cell line and showed increased replication rates in cultured primary cardiac myocytes of mouse, rat, and naive HL-1 cells in vitro, whereas it was unable to establish murine cardiac infection in vivo. Resistance of HL-1(CVB3) cells to CVB3-HL1 was associated with reduction of coxsackievirus and adenovirus receptor (CAR) expression. Decreasing host cell CAR expression was partially overcome by the CVB3-HL1 variant through CAR-independent entry into resistant cells. Moreover, CVB3-HL1 conserved the ability to infect cells via CAR. The employment of a soluble CAR variant resulted in the complete cure of HL-1(CVB3) cells with respect to the adapted virus. In conclusion, this is the first report of a CVB3 carrier-state infection in a cardiomyocyte cell line, revealing natural coevolution of CAR downregulation with CAR-independent viral entry in resistant host cells as an important mechanism of induction of CVB3 persistence.

  10. Virus-Host Coevolution in a Persistently Coxsackievirus B3-Infected Cardiomyocyte Cell Line ▿

    PubMed Central

    Pinkert, Sandra; Klingel, Karin; Lindig, Vanessa; Dörner, Andrea; Zeichhardt, Heinz; Spiller, O. Brad; Fechner, Henry

    2011-01-01

    Coevolution of virus and host is a process that emerges in persistent virus infections. Here we studied the coevolutionary development of coxsackievirus B3 (CVB3) and cardiac myocytes representing the major target cells of CVB3 in the heart in a newly established persistently CVB3-infected murine cardiac myocyte cell line, HL-1CVB3. CVB3 persistence in HL-1CVB3 cells represented a typical carrier-state infection with high levels (106 to 108 PFU/ml) of infectious virus produced from only a small proportion (approximately 10%) of infected cells. CVB3 persistence was characterized by the evolution of a CVB3 variant (CVB3-HL1) that displayed strongly increased cytotoxicity in the naive HL-1 cell line and showed increased replication rates in cultured primary cardiac myocytes of mouse, rat, and naive HL-1 cells in vitro, whereas it was unable to establish murine cardiac infection in vivo. Resistance of HL-1CVB3 cells to CVB3-HL1 was associated with reduction of coxsackievirus and adenovirus receptor (CAR) expression. Decreasing host cell CAR expression was partially overcome by the CVB3-HL1 variant through CAR-independent entry into resistant cells. Moreover, CVB3-HL1 conserved the ability to infect cells via CAR. The employment of a soluble CAR variant resulted in the complete cure of HL-1CVB3 cells with respect to the adapted virus. In conclusion, this is the first report of a CVB3 carrier-state infection in a cardiomyocyte cell line, revealing natural coevolution of CAR downregulation with CAR-independent viral entry in resistant host cells as an important mechanism of induction of CVB3 persistence. PMID:21976640

  11. Virus-host coevolution in a persistently coxsackievirus B3-infected cardiomyocyte cell line.

    PubMed

    Pinkert, Sandra; Klingel, Karin; Lindig, Vanessa; Dörner, Andrea; Zeichhardt, Heinz; Spiller, O Brad; Fechner, Henry

    2011-12-01

    Coevolution of virus and host is a process that emerges in persistent virus infections. Here we studied the coevolutionary development of coxsackievirus B3 (CVB3) and cardiac myocytes representing the major target cells of CVB3 in the heart in a newly established persistently CVB3-infected murine cardiac myocyte cell line, HL-1(CVB3). CVB3 persistence in HL-1(CVB3) cells represented a typical carrier-state infection with high levels (10(6) to 10(8) PFU/ml) of infectious virus produced from only a small proportion (approximately 10%) of infected cells. CVB3 persistence was characterized by the evolution of a CVB3 variant (CVB3-HL1) that displayed strongly increased cytotoxicity in the naive HL-1 cell line and showed increased replication rates in cultured primary cardiac myocytes of mouse, rat, and naive HL-1 cells in vitro, whereas it was unable to establish murine cardiac infection in vivo. Resistance of HL-1(CVB3) cells to CVB3-HL1 was associated with reduction of coxsackievirus and adenovirus receptor (CAR) expression. Decreasing host cell CAR expression was partially overcome by the CVB3-HL1 variant through CAR-independent entry into resistant cells. Moreover, CVB3-HL1 conserved the ability to infect cells via CAR. The employment of a soluble CAR variant resulted in the complete cure of HL-1(CVB3) cells with respect to the adapted virus. In conclusion, this is the first report of a CVB3 carrier-state infection in a cardiomyocyte cell line, revealing natural coevolution of CAR downregulation with CAR-independent viral entry in resistant host cells as an important mechanism of induction of CVB3 persistence. PMID:21976640

  12. Virus-host interactions in persistently FMDV-infected cells derived from bovine pharynx.

    PubMed

    O'Donnell, V; Pacheco, J M; Larocco, Michael; Gladue, D P; Pauszek, S J; Smoliga, G; Krug, P W; Baxt, B; Borca, M V; Rodriguez, L

    2014-11-01

    Foot-and-mouth disease virus (FMDV) produces a disease in cattle characterized by vesicular lesions and a persistent infection with asymptomatic low-level production of virus in pharyngeal tissues. Here we describe the establishment of a persistently infected primary cell culture derived from bovine pharynx tissue (PBPT) infected with FMDV serotype O1 Manisa, where surviving cells were serially passed until a persistently infected culture was generated. Characterization of the persistent virus demonstrated changes in its plaque size, ability to grow in different cell lines, and change in the use of integrins as receptors, when compared with the parental virus. These results demonstrate the establishment of persistently infected PBPT cell cultures where co-adaptation has taken place between the virus and host cells. This in vitro model for FMDV persistence may help further understanding of the molecular mechanisms of the cattle carrier state.

  13. Propofol Increases Host Susceptibility to Microbial Infection by Reducing Subpopulations of Mature Immune Effector Cells at Sites of Infection

    PubMed Central

    Visvabharathy, Lavanya; Xayarath, Bobbi; Weinberg, Guy; Shilling, Rebecca A.; Freitag, Nancy E.

    2015-01-01

    Anesthetics are known to modulate host immune responses, but separating the variables of surgery from anesthesia when analyzing hospital acquired infections is often difficult. Here, the bacterial pathogen Listeria monocytogenes (Lm) was used to assess the impact of the common anesthetic propofol on host susceptibility to infection. Brief sedation of mice with physiologically relevant concentrations of propofol increased bacterial burdens in target organs by more than 10,000-fold relative to infected control animals. The adverse effects of propofol sedation on immune clearance of Lm persisted after recovery from sedation, as animals given the drug remained susceptible to infection for days following anesthesia. In contrast to propofol, sedation with alternative anesthetics such as ketamine/xylazine or pentobarbital did not increase susceptibility to systemic Lm infection. Propofol altered systemic cytokine and chemokine expression during infection, and prevented effective bacterial clearance by inhibiting the recruitment and/or activity of immune effector cells at sites of infection. Propofol exposure induced a marked reduction in marginal zone macrophages in the spleens of Lm infected mice, resulting in bacterial dissemination into deep tissue. Propofol also significantly increased mouse kidney abscess formation following infection with the common nosocomial pathogen Staphylococcus aureus. Taken together, these data indicate that even brief exposure to propofol severely compromises host resistance to microbial infection for days after recovery from sedation. PMID:26381144

  14. Infection with Toxoplasma gondii results in dysregulation of the host cell cycle

    PubMed Central

    Molestina, Robert E.; El-Guendy, Nadia; Sinai, Anthony P.

    2009-01-01

    SUMMARY Mammalian cells infected with Toxoplasma gondii are characterized by a profound reprogramming of gene expression. We examined whether such transcriptional responses were linked to changes in the cell cycle of the host. Human foreskin fibroblasts (HFF) in the G0/G1 phase of the cell cycle were infected with T. gondii and FACS analysis of DNA content was performed. Cell cycle profiles revealed a promotion into the S phase followed by an arrest towards the G2/M boundary with infection. This response was markedly different from that of growth factor stimulation which caused cell cycle entry and completion. Transcriptional profiles of T. gondii-infected HFF showed sustained increases in transcripts associated with a G1/S transition and DNA synthesis coupled to an abrogation of cell cycle regulators critical in G2/M transition relative to growth factor stimulation. These divergent responses correlated with a distinct temporal modulation of the critical cell cycle regulator kinase ERK by infection. While the kinetics of ERK phosphorylation by EGF showed rapid and sustained activation, infected cells displayed an oscillatory pattern of activation. Our results suggest that T. gondii infection induces and maintains a “proliferation response” in the infected cell which may fulfill critical growth requirements of the parasite during intracellular residence. PMID:18182087

  15. Neisseria gonorrhoeae infection protects human endocervical epithelial cells from apoptosis via expression of host antiapoptotic proteins.

    PubMed

    Follows, S A; Murlidharan, J; Massari, P; Wetzler, L M; Genco, C A

    2009-09-01

    Several microbial pathogens can modulate the host apoptotic response to infection, which may contribute to immune evasion. Various studies have reported that infection with the sexually transmitted disease pathogen Neisseria gonorrhoeae can either inhibit or induce apoptosis. N. gonorrhoeae infection initiates at the mucosal epithelium, and in women, cells from the ectocervix and endocervix are among the first host cells encountered by this pathogen. In this study, we defined the antiapoptotic effect of N. gonorrhoeae infection in human endocervical epithelial cells (End/E6E7 cells). We first established that N. gonorrhoeae strain FA1090B failed to induce cell death in End/E6E7 cells. Subsequently, we demonstrated that stimulation with N. gonorrhoeae protected these cells from staurosporine (STS)-induced apoptosis. Importantly, only End/E6E7 cells incubated with live bacteria and in direct association with N. gonorrhoeae were protected from STS-induced apoptosis, while heat-killed and antibiotic-killed bacteria failed to induce protection. Stimulation of End/E6E7 cells with live N. gonorrhoeae induced NF-kappaB activation and resulted in increased gene expression of the NF-kappaB-regulated antiapoptotic genes bfl-1, cIAP-2, and c-FLIP. Furthermore, cIAP-2 protein levels also increased in End/E6E7 cells incubated with gonococci. Collectively, our results indicate that the antiapoptotic effect of N. gonorrhoeae in human endocervical epithelial cells results from live infection via expression of host antiapoptotic proteins. Securing an intracellular niche through the inhibition of apoptosis may be an important mechanism utilized by N. gonorrhoeae for microbial survival and immune evasion in cervical epithelial cells. PMID:19546192

  16. Host cell pigmentation in Scenedesmus dimorphus as a beacon for nascent parasite infection.

    PubMed

    Collins, Aaron M; Jones, Howland D T; McBride, Robert C; Behnke, Craig; Timlin, Jerilyn A

    2014-09-01

    Biofuels derived from the mass cultivation of algae represent an emerging industry that aims to partially displace petroleum based fuels. Outdoor, open-pond, and raceway production facilities are attractive options for the mass culture of algae however, this mode of cultivation leaves the algae susceptible to epidemics from a variety of environmental challenges. Infestations can result in complete collapse of the algal populations and destruction of their valuable products making it paramount to understand the host-pathogen relationships of known algal pests in order to develop mitigation strategies. In the present work, we characterize the spatial-temporal response of photosynthetic pigments in Scenedesmus dimorphus to infection from Amoeboaphelidium protococcarum, a destructive endoparasite, with the goal of understanding the potential for early detection of infection via host pigment changes. We employed a hyperspectral confocal fluorescence microscope to quantify these changes in pigmentation with high spatial and spectral resolution during early parasite infection. Carotenoid abundance and autofluorescence increased within the first 24 h of infection while chlorophyll emission remained constant. Changes in host cell photosynthesis and bulk chlorophyll content were found to lag behind parasite replication. The results herein raise the possibility of using host-cell pigment changes as indicators of nascent parasite infection. PMID:24931928

  17. Host cell pigmentation in Scenedesmus dimorphus as a beacon for nascent parasite infection.

    PubMed

    Collins, Aaron M; Jones, Howland D T; McBride, Robert C; Behnke, Craig; Timlin, Jerilyn A

    2014-09-01

    Biofuels derived from the mass cultivation of algae represent an emerging industry that aims to partially displace petroleum based fuels. Outdoor, open-pond, and raceway production facilities are attractive options for the mass culture of algae however, this mode of cultivation leaves the algae susceptible to epidemics from a variety of environmental challenges. Infestations can result in complete collapse of the algal populations and destruction of their valuable products making it paramount to understand the host-pathogen relationships of known algal pests in order to develop mitigation strategies. In the present work, we characterize the spatial-temporal response of photosynthetic pigments in Scenedesmus dimorphus to infection from Amoeboaphelidium protococcarum, a destructive endoparasite, with the goal of understanding the potential for early detection of infection via host pigment changes. We employed a hyperspectral confocal fluorescence microscope to quantify these changes in pigmentation with high spatial and spectral resolution during early parasite infection. Carotenoid abundance and autofluorescence increased within the first 24 h of infection while chlorophyll emission remained constant. Changes in host cell photosynthesis and bulk chlorophyll content were found to lag behind parasite replication. The results herein raise the possibility of using host-cell pigment changes as indicators of nascent parasite infection.

  18. Mycobacterium-Host Cell Relationships in Granulomatous Lesions in a Mouse Model of Latent Tuberculous Infection.

    PubMed

    Ufimtseva, Elena

    2015-01-01

    Tuberculosis (TB) is a dangerous infectious disease characterized by a tight interplay between mycobacteria and host cells in granulomatous lesions (granulomas) during the latent, asymptomatic stage of infection. Mycobacterium-host cell relationships were analyzed in granulomas obtained from various organs of BALB/c mice with chronic TB infection caused by in vivo exposure to the Bacillus Calmette-Guérin (BCG) vaccine. Acid-fast BCG-mycobacteria were found to be morphologically and functionally heterogeneous (in size, shape, and replication rates in colonies) in granuloma macrophages, dendritic cells, and multinucleate Langhans giant cells. Cord formation by BCG-mycobacteria in granuloma cells has been observed. Granuloma macrophages retained their ability to ingest damaged lymphocytes and thrombocytes in the phagosomes; however, their ability to destroy BCG-mycobacteria contained in these cells was compromised. No colocalization of BCG-mycobacteria and the LysoTracker dye was observed in the mouse cells. Various relationships between granuloma cells and BCG-mycobacteria were observed in different mice belonging to the same line. Several mice totally eliminated mycobacterial infection. Granulomas in the other mice had mycobacteria actively replicating in cells of different types and forming cords, which is an indicator of mycobacterial virulence and, probably, a marker of the activation of tuberculous infection in animals.

  19. Mycobacterium-Host Cell Relationships in Granulomatous Lesions in a Mouse Model of Latent Tuberculous Infection.

    PubMed

    Ufimtseva, Elena

    2015-01-01

    Tuberculosis (TB) is a dangerous infectious disease characterized by a tight interplay between mycobacteria and host cells in granulomatous lesions (granulomas) during the latent, asymptomatic stage of infection. Mycobacterium-host cell relationships were analyzed in granulomas obtained from various organs of BALB/c mice with chronic TB infection caused by in vivo exposure to the Bacillus Calmette-Guérin (BCG) vaccine. Acid-fast BCG-mycobacteria were found to be morphologically and functionally heterogeneous (in size, shape, and replication rates in colonies) in granuloma macrophages, dendritic cells, and multinucleate Langhans giant cells. Cord formation by BCG-mycobacteria in granuloma cells has been observed. Granuloma macrophages retained their ability to ingest damaged lymphocytes and thrombocytes in the phagosomes; however, their ability to destroy BCG-mycobacteria contained in these cells was compromised. No colocalization of BCG-mycobacteria and the LysoTracker dye was observed in the mouse cells. Various relationships between granuloma cells and BCG-mycobacteria were observed in different mice belonging to the same line. Several mice totally eliminated mycobacterial infection. Granulomas in the other mice had mycobacteria actively replicating in cells of different types and forming cords, which is an indicator of mycobacterial virulence and, probably, a marker of the activation of tuberculous infection in animals. PMID:26064970

  20. Mycobacterium-Host Cell Relationships in Granulomatous Lesions in a Mouse Model of Latent Tuberculous Infection

    PubMed Central

    2015-01-01

    Tuberculosis (TB) is a dangerous infectious disease characterized by a tight interplay between mycobacteria and host cells in granulomatous lesions (granulomas) during the latent, asymptomatic stage of infection. Mycobacterium-host cell relationships were analyzed in granulomas obtained from various organs of BALB/c mice with chronic TB infection caused by in vivo exposure to the Bacillus Calmette-Guérin (BCG) vaccine. Acid-fast BCG-mycobacteria were found to be morphologically and functionally heterogeneous (in size, shape, and replication rates in colonies) in granuloma macrophages, dendritic cells, and multinucleate Langhans giant cells. Cord formation by BCG-mycobacteria in granuloma cells has been observed. Granuloma macrophages retained their ability to ingest damaged lymphocytes and thrombocytes in the phagosomes; however, their ability to destroy BCG-mycobacteria contained in these cells was compromised. No colocalization of BCG-mycobacteria and the LysoTracker dye was observed in the mouse cells. Various relationships between granuloma cells and BCG-mycobacteria were observed in different mice belonging to the same line. Several mice totally eliminated mycobacterial infection. Granulomas in the other mice had mycobacteria actively replicating in cells of different types and forming cords, which is an indicator of mycobacterial virulence and, probably, a marker of the activation of tuberculous infection in animals. PMID:26064970

  1. Targeting host syntaxin-5 preferentially blocks Leishmania parasitophorous vacuole development in infected cells and limits experimental Leishmania infections.

    PubMed

    Canton, Johnathan; Kima, Peter E

    2012-10-01

    Our previous observations established a role for syntaxin-5 in the development of Leishmania parasitophorous vacuoles (LPVs). In this study, we took advantage of the recent identification of Retro-2, a small organic molecule that can cause the redistribution of syntaxin-5; we show herein that Retro-2 blocks LPV development within 2 hours of adding it to cells infected with Leishmania amazonensis. In infected cells incubated for 48 hours with Retro-2, LPV development was significantly limited; furthermore, infected cells harbored four to five times fewer parasites than infected cells incubated in vehicle alone. In vivo studies revealed that Retro-2 curbed experimental L. amazonensis infections in a dose-dependent manner. Retro-2 did not have any appreciable effect on the host cell physiological characteristics; furthermore, it had no apparent toxicity in experimental animals. An unexpected, but welcome, finding was that Retro-2 inhibited the replication of Leishmania parasites in axenic cultures. This study is significant because it identifies an endoplasmic reticulum/Golgi SNARE as a potential target for the control of Leishmania infections; moreover, it suggests that small organic molecules can be identified that can selectively disrupt the vesicle fusion machinery that promotes the development of pathogen-containing compartments without exerting toxic effects on the host.

  2. Rodent Plasmodium-infected red blood cells: imaging their fates and interactions within their hosts.

    PubMed

    Claser, Carla; Malleret, Benoit; Peng, Kaitian; Bakocevic, Nadja; Gun, Sin Yee; Russell, Bruce; Ng, Lai Guan; Rénia, Laurent

    2014-02-01

    Malaria, a disease caused by the Plasmodium parasite, remains one of the most deadly infectious diseases known to mankind. The parasite has a complex life cycle, of which only the erythrocytic stage is responsible for the diverse pathologies induced during infection. To date, the disease mechanisms that underlie these pathologies are still poorly understood. In the case of infections caused by Plasmodium falciparum, the species responsible for most malaria related deaths, pathogenesis is thought to be due to the sequestration of infected red blood cells (IRBCs) in deep tissues. Other human and rodent malaria parasite species are also known to exhibit sequestration. Here, we review the different techniques that allow researchers to study how rodent malaria parasites modify their host cells, the distribution of IRBCs in vivo as well as the interactions between IRBCs and host tissues. PMID:23892178

  3. Selective alterations of the host cell architecture upon infection with parvovirus minute virus of mice

    SciTech Connect

    Nueesch, Juerg P.F. . E-mail: jpf.nuesch@dkfz-heidelberg.de; Lachmann, Sylvie; Rommelaere, Jean

    2005-01-05

    During a productive infection, the prototype strain of parvovirus minute virus of mice (MVMp) induces dramatic morphological alterations to the fibroblast host cell A9, resulting in cell lysis and progeny virus release. In order to understand the mechanisms underlying these changes, we characterized the fate of various cytoskeletal filaments and investigated the nuclear/cytoplasmic compartmentalization of infected cells. While most pronounced effects could be seen on micro- and intermediate filaments, manifest in dramatic rearrangements and degradation of filamentous (F-)actin and vimentin structures, only little impact could be seen on microtubules or the nuclear envelope during the entire monitored time of infection. To further analyze the disruption of the cytoskeletal structures, we investigated the viral impact on selective regulatory pathways. Thereby, we found a correlation between microtubule stability and MVM-induced phosphorylation of {alpha}/{beta} tubulin. In contrast, disassembly of actin filaments late in infection could be traced back to the disregulation of two F-actin associated proteins gelsolin and Wiscott-Aldrich Syndrome Protein (WASP). Thereby, an increase in the amount of gelsolin, an F-actin severing protein was observed during infection, accounting for the disruption of stress fibers upon infection. Concomitantly, the actin polymerization activity also diminished due to a loss of WASP, the activator protein of the actin polymerization machinery the Arp2/3 complex. No effects could be seen in amount and distribution of other F-actin regulatory factors such as cortactin, cofilin, and profilin. In summary, the selective attack of MVM towards distinct host cell cytoskeletal structures argues for a regulatory feature during infection, rather than a collapse of the host cell as a mere side effect of virus production.

  4. Essential Domains of Anaplasma phagocytophilum Invasins Utilized to Infect Mammalian Host Cells

    PubMed Central

    Seidman, David; Hebert, Kathryn S.; Truchan, Hilary K.; Miller, Daniel P.; Tegels, Brittney K.; Marconi, Richard T.; Carlyon, Jason A.

    2015-01-01

    Anaplasma phagocytophilum causes granulocytic anaplasmosis, an emerging disease of humans and domestic animals. The obligate intracellular bacterium uses its invasins OmpA, Asp14, and AipA to infect myeloid and non-phagocytic cells. Identifying the domains of these proteins that mediate binding and entry, and determining the molecular basis of their interactions with host cell receptors would significantly advance understanding of A. phagocytophilum infection. Here, we identified the OmpA binding domain as residues 59 to 74. Polyclonal antibody generated against a peptide spanning OmpA residues 59 to 74 inhibited A. phagocytophilum infection of host cells and binding to its receptor, sialyl Lewis x (sLex-capped P-selectin glycoprotein ligand 1. Molecular docking analyses predicted that OmpA residues G61 and K64 interact with the two sLex sugars that are important for infection, α2,3-sialic acid and α1,3-fucose. Amino acid substitution analyses demonstrated that K64 was necessary, and G61 was contributory, for recombinant OmpA to bind to host cells and competitively inhibit A. phagocytophilum infection. Adherence of OmpA to RF/6A endothelial cells, which express little to no sLex but express the structurally similar glycan, 6-sulfo-sLex, required α2,3-sialic acid and α1,3-fucose and was antagonized by 6-sulfo-sLex antibody. Binding and uptake of OmpA-coated latex beads by myeloid cells was sensitive to sialidase, fucosidase, and sLex antibody. The Asp14 binding domain was also defined, as antibody specific for residues 113 to 124 inhibited infection. Because OmpA, Asp14, and AipA each contribute to the infection process, it was rationalized that the most effective blocking approach would target all three. An antibody cocktail targeting the OmpA, Asp14, and AipA binding domains neutralized A. phagocytophilum binding and infection of host cells. This study dissects OmpA-receptor interactions and demonstrates the effectiveness of binding domain-specific antibodies

  5. Macrophage Activation Redirects Yersinia-Infected Host Cell Death from Apoptosis to Caspase-1-Dependent Pyroptosis

    PubMed Central

    Bergsbaken, Tessa; Cookson, Brad T

    2007-01-01

    Infection of macrophages by Yersinia species results in YopJ-dependent apoptosis, and naïve macrophages are highly susceptible to this form of cell death. Previous studies have demonstrated that macrophages activated with lipopolysaccharide (LPS) prior to infection are resistant to YopJ-dependent cell death; we found this simultaneously renders macrophages susceptible to killing by YopJ− Yersinia pseudotuberculosis (Yptb). YopJ− Yptb-induced macrophage death was dependent on caspase-1 activation, resulting in rapid permeability to small molecules, followed by membrane breakdown and DNA damage, and accompanied by cleavage and release of proinflammatory interleukin-18. Induction of caspase-1-dependent death, or pyroptosis, required the bacterial type III translocon but none of its known translocated proteins. Wild-type Yptb infection also triggered pyroptosis: YopJ-dependent activation of proapoptotic caspase-3 was significantly delayed in activated macrophages and resulted in caspase-1-dependent pyroptosis. The transition to susceptibility was not limited to LPS activation; it was also seen in macrophages activated with other Toll-like receptor (TLR) ligands and intact nonviable bacteria. Yptb infection triggered macrophage activation and activation of caspase-1 in vivo. Y. pestis infection of activated macrophages also stimulated caspase-1 activation. These results indicate that host signaling triggered by TLR and other activating ligands during the course of Yersinia infection redirects both the mechanism of host cell death and the downstream consequences of death by shifting from noninflammatory apoptosis to inflammatory pyroptosis. PMID:17983266

  6. Impact of Adenovirus infection in host cell metabolism evaluated by (1)H-NMR spectroscopy.

    PubMed

    Silva, Ana Carina; P Teixeira, Ana; M Alves, Paula

    2016-08-10

    Adenovirus-based vectors are powerful vehicles for gene transfer applications in vaccination and gene therapy. Although highly exploited in the clinical setting, key aspects of the adenovirus biology are still not well understood, in particular the subversion of host cell metabolism during viral infection and replication. The aim of this work was to gain insights on the metabolism of two human cell lines (HEK293 and an amniocyte-derived cell line, 1G3) after infection with an adenovirus serotype 5 vector (AdV5). In order to profile metabolic alterations, we used (1)H-NMR spectroscopy, which allowed the quantification of 35 metabolites in cell culture supernatants with low sample preparation and in a relatively short time. Significant differences between both cell lines in non-infected cultures were identified, namely in glutamine and acetate metabolism, as well as by-product secretion. The main response to AdV5 infection was an increase in glucose consumption and lactate production rates. Moreover, cultures performed with or without glutamine supplementation confirmed the exhaustion of this amino acid as one of the main causes of lower AdV5 production at high cell densities (10- and 1.5-fold less specific yields in HEK293 and 1G3 cells, respectively), and highlighted different degrees of glutamine dependency of adenovirus replication in each cell line. The observed metabolic alterations associated with AdV5 infection and specificity of the host cell line can be useful for targeted bioprocess optimization. PMID:27215342

  7. Immunosuppressive CD71+ erythroid cells compromise neonatal host defence against infection

    PubMed Central

    Elahi, Shokrollah; Ertelt, James M.; Kinder, Jeremy M.; Jiang, Tony T.; Zhang, Xuzhe; Xin, Lijun; Chaturvedi, Vandana; Strong, Beverly S.; Qualls, Joseph E.; Steinbrecher, Kris A.; Kalfa, Theodosia A.; Shaaban, Aimen F.; Way, Sing Sing

    2014-01-01

    Newborn infants are highly susceptible to infection. This defect in host defence has generally been ascribed to the immaturity of neonatal immune cells; however, the degree of hyporesponsiveness is highly variable and depends on the stimulation conditions1–7. These discordant responses illustrate the need for a more unified explanation for why immunity is compromised in neonates. Here we show that physiologically enriched CD71+ erythroid cells in neonatal mice and human cord blood have distinctive immunosuppressive properties. The production of innate immune protective cytokines by adult cells is diminished after transfer to neonatal mice or after co-culture with neonatal splenocytes. Neonatal CD71+ cells express the enzyme arginase-2, and arginase activity is essential for the immunosuppressive properties of these cells because molecular inhibition of this enzyme or supplementation with l-arginine overrides immunosuppression. In addition, the ablation of CD71+ cells in neonatal mice, or the decline in number of these cells as postnatal development progresses parallels the loss of suppression, and restored resistance to the perinatal pathogens Listeria monocytogenes and Escherichia coli8,9. However, CD71+ cell-mediated susceptibility to infection is counterbalanced by CD71+ cell-mediated protection against aberrant immune cell activation in the intestine, where colonization with commensal microorganisms occurs swiftly after parturition10,11.Conversely, circumventing such colonization by using antimicrobials or gnotobiotic germ-free mice overrides these protective benefits. Thus, CD71+ cells quench the excessive inflammation induced by abrupt colonization with commensal microorganisms after parturition. This finding challenges the idea that the susceptibility of neonates to infection reflects immune-cell-intrinsic defects and instead highlights processes that are developmentally more essential and inadvertently mitigate innate immune protection. We anticipate that

  8. Immunosuppressive CD71+ erythroid cells compromise neonatal host defence against infection

    NASA Astrophysics Data System (ADS)

    Elahi, Shokrollah; Ertelt, James M.; Kinder, Jeremy M.; Jiang, Tony T.; Zhang, Xuzhe; Xin, Lijun; Chaturvedi, Vandana; Strong, Beverly S.; Qualls, Joseph E.; Steinbrecher, Kris A.; Kalfa, Theodosia A.; Shaaban, Aimen F.; Way, Sing Sing

    2013-12-01

    Newborn infants are highly susceptible to infection. This defect in host defence has generally been ascribed to the immaturity of neonatal immune cells; however, the degree of hyporesponsiveness is highly variable and depends on the stimulation conditions. These discordant responses illustrate the need for a more unified explanation for why immunity is compromised in neonates. Here we show that physiologically enriched CD71+ erythroid cells in neonatal mice and human cord blood have distinctive immunosuppressive properties. The production of innate immune protective cytokines by adult cells is diminished after transfer to neonatal mice or after co-culture with neonatal splenocytes. Neonatal CD71+ cells express the enzyme arginase-2, and arginase activity is essential for the immunosuppressive properties of these cells because molecular inhibition of this enzyme or supplementation with L-arginine overrides immunosuppression. In addition, the ablation of CD71+ cells in neonatal mice, or the decline in number of these cells as postnatal development progresses parallels the loss of suppression, and restored resistance to the perinatal pathogens Listeria monocytogenes and Escherichia coli. However, CD71+ cell-mediated susceptibility to infection is counterbalanced by CD71+ cell-mediated protection against aberrant immune cell activation in the intestine, where colonization with commensal microorganisms occurs swiftly after parturition. Conversely, circumventing such colonization by using antimicrobials or gnotobiotic germ-free mice overrides these protective benefits. Thus, CD71+ cells quench the excessive inflammation induced by abrupt colonization with commensal microorganisms after parturition. This finding challenges the idea that the susceptibility of neonates to infection reflects immune-cell-intrinsic defects and instead highlights processes that are developmentally more essential and inadvertently mitigate innate immune protection. We anticipate that these

  9. Cutting edge: IL-17-secreting innate lymphoid cells are essential for host defense against fungal infection.

    PubMed

    Gladiator, André; Wangler, Nicolette; Trautwein-Weidner, Kerstin; LeibundGut-Landmann, Salomé

    2013-01-15

    IL-17-mediated immunity has emerged as a crucial host defense mechanism against fungal infections. Although Th cells are generally thought to act as the major source of IL-17 in response to Candida albicans, we show that fungal control is mediated by IL-17-secreting innate lymphoid cells (ILCs) and not by Th17 cells. By using a mouse model of oropharyngeal candidiasis we found that IL-17A and IL-17F, which are both crucial for pathogen clearance, are produced promptly upon infection in an IL-23-dependent manner, and that ILCs in the oral mucosa are the main source for these cytokines. Ab-mediated depletion of ILCs in RAG1-deficient mice or ILC deficiency in retinoic acid-related orphan receptor c(-/-) mice resulted in a complete failure to control the infection. Taken together, our data uncover the cellular basis for the IL-23/IL-17 axis, which acts right at the onset of infection when it is most needed for fungal control and host protection.

  10. Early shutoff of host protein synthesis in cells infected with herpes simplex viruses.

    PubMed

    Matis, J; Kúdelová, M

    2001-01-01

    Herpes simplex viruses 1 (HSV-1) and 2 (HSV-2) are capable of suppressing the host cell protein synthesis even without viral gene expression. This phenomenon is known as the early shutoff or as the virion-associated host shutoff (vhs) to emphasize that it is mediated by a component of infecting virions which is a product of the UL41 (vhs) gene. The UL41 encoded protein is a functional tegument protein also present in light (L) particles and is not essential for virus replication. The major product of UL41 gene is a 58 K phosphoprotein. At least two forms of UL41 protein differing in the extent of phosphorylation are present in HSV-1-infected cells. HSV-2 compared to HSV-1 strains display a stronger vhs phenotype. However, in superinfection experiments the less strong vhs phenotype is dominant. UL41 protein triggers disruption of polysomes and rapid degradation of all host and viral mRNAs and blocks a reporter gene expression without other HSVs proteins. The available evidence suggests that UL41 protein is either itself a ribonuclease (RNase) or a subunit of RNase that contains also one or more cellular subunits. UL41 protein is capable of interacting with a transactivator of an alpha-gene, the alpha-transinducing factor (alpha-TIF). Interaction of UL41 protein with alpha-TIF down regulates the UL41 (vhs) gene activity during lytic infection. The possible role of other viral proteins in the shutoff is discussed.

  11. Coxiella burnetii Infects Primary Bovine Macrophages and Limits Their Host Cell Response.

    PubMed

    Sobotta, Katharina; Hillarius, Kirstin; Mager, Marvin; Kerner, Katharina; Heydel, Carsten; Menge, Christian

    2016-06-01

    Although domestic ruminants have long been recognized as the main source of human Q fever, little is known about the lifestyle that the obligate intracellular Gram-negative bacterium Coxiella burnetii adopts in its animal host. Because macrophages are considered natural target cells of the pathogen, we established primary bovine monocyte-derived macrophages (MDM) as an in vitro infection model to study reservoir host-pathogen interactions at the cellular level. In addition, bovine alveolar macrophages were included to take cell type peculiarities at a host entry site into account. Cell cultures were inoculated with the virulent strain Nine Mile I (NMI; phase I) or the avirulent strain Nine Mile II (NMII; phase II). Macrophages from both sources internalized NMI and NMII. MDM were particularly permissive for NMI internalization, but NMI and NMII replicated with similar kinetics in these cells. MDM responded to inoculation with a general upregulation of Th1-related cytokines such as interleukin-1β (IL-1β), IL-12, and tumor necrosis factor alpha (TNF-α) early on (3 h postinfection). However, inflammatory responses rapidly declined when C. burnetii replication started. C. burnetii infection inhibited translation and release of IL-1β and vastly failed to stimulate increased expression of activation markers, such as CD40, CD80, CD86, and major histocompatibility complex (MHC) molecules. Such capability of limiting proinflammatory responses may help Coxiella to protect itself from clearance by the host immune system. The findings provide the first detailed insight into C. burnetii-macrophage interactions in ruminants and may serve as a basis for assessing the virulence and the host adaptation of C. burnetii strains. PMID:27021246

  12. Comparative phosphoproteomics reveals components of host cell invasion and post-transcriptional regulation during Francisella infection

    SciTech Connect

    Nakayasu, Ernesto S.; Tempel, Rebecca; Cambronne, Xiaolu A.; Petyuk, Vladislav A.; Jones, Marcus B.; Gritsenko, Marina A.; Monroe, Matthew E.; Yang, Feng; Smith, Richard D.; Adkins, Joshua N.; Heffron, Fred

    2013-09-22

    Francisella tularensis is a facultative intracellular bacterium that causes the deadly disease tularemia. Most evidence suggests that Francisella is not well recognized by the innate immune system that normally leads to cytokine expression and cell death. In previous work, we identified new bacterial factors that were hyper-cytotoxic to macrophages. Four of the identified hyper-cytotoxic strains (lpcC, manB, manC and kdtA) had an impaired lipopolysaccharide (LPS) synthesis and produced an exposed lipid A lacking the O-antigen. These mutants were not only hyper-cytotoxic but also were phagocytosed at much higher rates compared to the wild type parent strain. To elucidate the cellular signaling underlying this enhanced phagocytosis and cell death, we performed a large-scale comparative phosphoproteomic analysis of cells infected with wild-type and delta-lpcC F. novicida. Our data suggest that not only actin but also intermediate filaments and microtubules are important for F. novicida entry into the host cells. In addition, we observed differential phosphorylation of tristetraprolin (TTP), a key component of the mRNA-degrading machinery that controls the expression of a variety of genes including many cytokines. Infection with the delta-lpcC mutant induced the hyper-phosphorylation and inhibition of TTP, leading to the production of cytokines such as IL-1beta and TNF-alpha which may kill the host cells by triggering apoptosis. Together, our data provide new insights for Francisella invasion and a post-transcriptional mechanism that prevents the expression of host immune response factors that controls infection by this pathogen.

  13. Deep Sequencing of HIV-Infected Cells: Insights into Nascent Transcription and Host-Directed Therapy

    PubMed Central

    Peng, Xinxia; Sova, Pavel; Green, Richard R.; Thomas, Matthew J.; Korth, Marcus J.; Proll, Sean; Xu, Jiabao; Cheng, Yanbing; Yi, Kang; Chen, Li; Peng, Zhiyu; Wang, Jun; Palermo, Robert E.

    2014-01-01

    ABSTRACT Polyadenylated mature mRNAs are the focus of standard transcriptome analyses. However, the profiling of nascent transcripts, which often include nonpolyadenylated RNAs, can unveil novel insights into transcriptional regulation. Here, we separately sequenced total RNAs (Total RNAseq) and mRNAs (mRNAseq) from the same HIV-1-infected human CD4+ T cells. We found that many nonpolyadenylated RNAs were differentially expressed upon HIV-1 infection, and we identified 8 times more differentially expressed genes at 12 h postinfection by Total RNAseq than by mRNAseq. These expression changes were also evident by concurrent changes in introns and were recapitulated by later mRNA changes, revealing an unexpectedly significant delay between transcriptional initiation and mature mRNA production early after HIV-1 infection. We computationally derived and validated the underlying regulatory programs, and we predicted drugs capable of reversing these HIV-1-induced expression changes followed by experimental confirmation. Our results show that combined total and mRNA transcriptome analysis is essential for fully capturing the early host response to virus infection and provide a framework for identifying candidate drugs for host-directed therapy against HIV/AIDS. IMPORTANCE In this study, we used mass sequencing to identify genes differentially expressed in CD4+ T cells during HIV-1 infection. To our surprise, we found many differentially expressed genes early after infection by analyzing both newly transcribed unprocessed pre-mRNAs and fully processed mRNAs, but not by analyzing mRNAs alone, indicating a significant delay between transcription initiation and mRNA production early after HIV-1 infection. These results also show that important findings could be missed by the standard practice of analyzing mRNAs alone. We then derived the regulatory mechanisms driving the observed expression changes using integrative computational analyses. Further, we predicted drugs that

  14. HIV Integration at Certain Sites in Host DNA Is Linked to the Expansion and Persistence of Infected Cells | Poster

    Cancer.gov

    Editor’s note: This article was originally published on the Center for Cancer Research website. When the Human Immunodeficiency Virus (HIV) infects a cell, the virus inserts a copy of its genetic material into the host cell’s DNA. The inserted genetic material, which is also called a provirus, is used to produce new viruses. Because the viral DNA can be inserted at many sites in the host cell DNA, the site of integration marks each infected cell. Patients infected with HIV are currently treated with combined antiretroviral therapy (cART), which prevents viral replication in the majority of treated patients. When cART is initiated, most HIV-infected cells die in one or two days, and more of the infected cells die over a period of weeks to months. However there are some long-lived infected cells that do not die, which prevents patients from being cured.

  15. The amastigote forms of Leishmania are experts at exploiting host cell processes to establish infection and persist.

    PubMed

    Kima, Peter E

    2007-08-01

    Leishmania are dimorphic protozoan parasites that live as flagellated forms in the gut of their sandfly vector and as aflagellated forms in their mammalian hosts. Although both parasite forms can infect macrophages and dendritic cells, they elicit distinct responses from mammalian cells. Amastigotes are the parasites forms that persist in the infected host; they infect cells recruited to lesions and disseminate the infection to secondary sites. In this review I discuss studies that have investigated the mechanisms that Leishmania amastigotes employ to harness the host cell's response to infection. It should be acknowledged that our understanding of the mechanisms deployed by Leishmania amastigotes to modulate the host cell's response to infection is still rudimentary. Nonetheless, the results show that amastigote interactions with mammalian cells promote the production of anti-inflammatory cytokines such as IL-10 and TGF-beta while suppressing the production of IL-12, superoxide and nitric oxide. An underlying issue that is considered is how these parasites that reside in sequestered vacuolar compartments target host cell processes in the cytosol or the nucleus; does this occur through the release of parasite molecules from parasitophorous vacuoles or by engaging and sustaining signalling pathways throughout the course of infection?

  16. NF-κB-dependent inhibition of apoptosis is essential for host cell survival during Rickettsia rickettsii infection

    PubMed Central

    Clifton, Dawn R.; Goss, Rachel A.; Sahni, Sanjeev K.; van Antwerp, Daniel; Baggs, Raymond B.; Marder, Victor J.; Silverman, David J.; Sporn, Lee Ann

    1998-01-01

    The possibility that bacteria may have evolved strategies to overcome host cell apoptosis was explored by using Rickettsia rickettsii, an obligate intracellular Gram-negative bacteria that is the etiologic agent of Rocky Mountain spotted fever. The vascular endothelial cell, the primary target cell during in vivo infection, exhibits no evidence of apoptosis during natural infection and is maintained for a sufficient time to allow replication and cell-to-cell spread prior to eventual death due to necrotic damage. Prior work in our laboratory demonstrated that R. rickettsii infection activates the transcription factor NF-κB and alters expression of several genes under its control. However, when R. rickettsii-induced activation of NF-κB was inhibited, apoptosis of infected but not uninfected endothelial cells rapidly ensued. In addition, human embryonic fibroblasts stably transfected with a superrepressor mutant inhibitory subunit IκB that rendered NF-κB inactivatable also underwent apoptosis when infected, whereas infected wild-type human embryonic fibroblasts survived. R. rickettsii, therefore, appeared to inhibit host cell apoptosis via a mechanism dependent on NF-κB activation. Apoptotic nuclear changes correlated with presence of intracellular organisms and thus this previously unrecognized proapoptotic signal, masked by concomitant NF-κB activation, likely required intracellular infection. Our studies demonstrate that a bacterial organism can exert an antiapoptotic effect, thus modulating the host cell’s apoptotic response to its own advantage by potentially allowing the host cell to remain as a site of infection. PMID:9539792

  17. Subcellular proteomic analysis of human host cells infected with H3N2 swine influenza virus.

    PubMed

    Wu, Xiaopeng; Wang, Sanying; Yu, Yang; Zhang, Jinyang; Sun, Zeyu; Yan, Yan; Zhou, Jiyong

    2013-11-01

    Cross-species transmissions of swine influenza viruses (SIVs) raise great public health concerns. In this study, subcellular proteomic profiles of human A549 cells inoculated with H3N2 subtype SIV were used to characterize dynamic cellular responses to infection. By 2DE and MS, 27 differentially expressed (13 upregulated, 14 downregulated) cytoplasmic proteins and 20 differentially expressed (13 upregulated, 7 downregulated) nuclear proteins were identified. Gene ontology analysis suggested that these differentially expressed proteins were mainly involved in cell death, stress response, lipid metabolism, cell signaling, and RNA PTMs. Moreover, 25 corresponding genes of the differentially expressed proteins were quantitated by real time RT-PCR to examine the transcriptional profiles between mock- and virus-infected A549 cells. Western blot analysis confirmed that changes in abundance of identified cellular proteins heterogeneous nuclear ribonucleoprotein (hnRNP) U, hnRNP C, ALDH1A1, tryptophanyl-tRNA synthetase, IFI35, and HSPB1 in H3N2 SIV-infected cells were consistent with results of 2DE analysis. By confocal microscopy, nucleus-to-cytoplasm translocation of hnRNP C and colocalization between the viral nonstructural protein 1 and hnRNP C as well as N-myc (and STAT) interactor were observed upon infection. Ingenuity Pathway Analysis revealed that cellular proteins altered during infection were grouped mainly into NFκB and interferon signaling networks. Collectively, these identified subcellular constituents provide an important framework for understanding host/SIV interactions and underlying mechanisms of SIV cross-species infection and pathogenesis.

  18. Host Cell Poly(ADP-Ribose) Glycohydrolase Is Crucial for Trypanosoma cruzi Infection Cycle

    PubMed Central

    Vilchez Larrea, Salomé C.; Schlesinger, Mariana; Kevorkian, María L.; Flawiá, Mirtha M.; Alonso, Guillermo D.; Fernández Villamil, Silvia H.

    2013-01-01

    Trypanosoma cruzi, etiological agent of Chagas’ disease, has a complex life cycle which involves the invasion of mammalian host cells, differentiation and intracellular replication. Here we report the first insights into the biological role of a poly(ADP-ribose) glycohydrolase in a trypanosomatid (TcPARG). In silico analysis of the TcPARG gene pointed out the conservation of key residues involved in the catalytic process and, by Western blot, we demonstrated that it is expressed in a life stage-dependant manner. Indirect immunofluorescence assays and electron microscopy using an anti-TcPARG antibody showed that this enzyme is localized in the nucleus independently of the presence of DNA damage or cell cycle stage. The addition of poly(ADP-ribose) glycohydrolase inhibitors ADP-HPD (adenosine diphosphate (hydroxymethyl) pyrrolidinediol) or DEA (6,9-diamino-2-ethoxyacridine lactate monohydrate) to the culture media, both at a 1 µM concentration, reduced in vitro epimastigote growth by 35% and 37% respectively, when compared to control cultures. We also showed that ADP-HPD 1 µM can lead to an alteration in the progression of the cell cycle in hydroxyurea synchronized cultures of T. cruzi epimastigotes. Outstandingly, here we demonstrate that the lack of poly(ADP-ribose) glycohydrolase activity in Vero and A549 host cells, achieved by chemical inhibition or iRNA, produces the reduction of the percentage of infected cells as well as the number of amastigotes per cell and trypomastigotes released, leading to a nearly complete abrogation of the infection process. We conclude that both, T. cruzi and the host, poly(ADP-ribose) glycohydrolase activities are important players in the life cycle of Trypanosoma cruzi, emerging as a promising therapeutic target for the treatment of Chagas’ disease. PMID:23776710

  19. Host cell poly(ADP-ribose) glycohydrolase is crucial for Trypanosoma cruzi infection cycle.

    PubMed

    Vilchez Larrea, Salomé C; Schlesinger, Mariana; Kevorkian, María L; Flawiá, Mirtha M; Alonso, Guillermo D; Fernández Villamil, Silvia H

    2013-01-01

    Trypanosoma cruzi, etiological agent of Chagas' disease, has a complex life cycle which involves the invasion of mammalian host cells, differentiation and intracellular replication. Here we report the first insights into the biological role of a poly(ADP-ribose) glycohydrolase in a trypanosomatid (TcPARG). In silico analysis of the TcPARG gene pointed out the conservation of key residues involved in the catalytic process and, by Western blot, we demonstrated that it is expressed in a life stage-dependant manner. Indirect immunofluorescence assays and electron microscopy using an anti-TcPARG antibody showed that this enzyme is localized in the nucleus independently of the presence of DNA damage or cell cycle stage. The addition of poly(ADP-ribose) glycohydrolase inhibitors ADP-HPD (adenosine diphosphate (hydroxymethyl) pyrrolidinediol) or DEA (6,9-diamino-2-ethoxyacridine lactate monohydrate) to the culture media, both at a 1 µM concentration, reduced in vitro epimastigote growth by 35% and 37% respectively, when compared to control cultures. We also showed that ADP-HPD 1 µM can lead to an alteration in the progression of the cell cycle in hydroxyurea synchronized cultures of T. cruzi epimastigotes. Outstandingly, here we demonstrate that the lack of poly(ADP-ribose) glycohydrolase activity in Vero and A549 host cells, achieved by chemical inhibition or iRNA, produces the reduction of the percentage of infected cells as well as the number of amastigotes per cell and trypomastigotes released, leading to a nearly complete abrogation of the infection process. We conclude that both, T. cruzi and the host, poly(ADP-ribose) glycohydrolase activities are important players in the life cycle of Trypanosoma cruzi, emerging as a promising therapeutic target for the treatment of Chagas' disease. PMID:23776710

  20. Alphavirus Infection: Host Cell Shut-Off and Inhibition of Antiviral Responses

    PubMed Central

    Fros, Jelke J.; Pijlman, Gorben P.

    2016-01-01

    Alphaviruses cause debilitating disease in humans and animals and are transmitted by blood-feeding arthropods, typically mosquitoes. With a traditional focus on two models, Sindbis virus and Semliki Forest virus, alphavirus research has significantly intensified in the last decade partly due to the re-emergence and dramatic expansion of chikungunya virus in Asia, Europe, and the Americas. As a consequence, alphavirus–host interactions are now understood in much more molecular detail, and important novel mechanisms have been elucidated. It has become clear that alphaviruses not only cause a general host shut-off in infected vertebrate cells, but also specifically suppress different host antiviral pathways using their viral nonstructural proteins, nsP2 and nsP3. Here we review the current state of the art of alphavirus host cell shut-off of viral transcription and translation, and describe recent insights in viral subversion of interferon induction and signaling, the unfolded protein response, and stress granule assembly. PMID:27294951

  1. Interaction with host factors exacerbates Trypanosoma cruzi cell invasion capacity upon oral infection.

    PubMed

    Covarrubias, Charles; Cortez, Mauro; Ferreira, Daniele; Yoshida, Nobuko

    2007-12-01

    Outbreaks of severe acute Chagas' disease acquired by oral infection, leading to death in some cases, have occurred in recent years. Using the mouse model, we investigated the basis of such virulence by analyzing a Trypanosoma cruzi isolate, SC, from a patient with severe acute clinical symptoms, who was infected by oral route. It has previously been shown that, upon oral inoculation into mice, T. cruzi metacyclic trypomastigotes invade the gastric mucosal epithelium by engaging the stage-specific surface glycoprotein gp82, whereas the surface molecule gp90 functions as a down-modulator of cell invasion. We found that, when orally inoculated into mice, metacyclic forms of the SC isolate, which express high levels of gp90, produced high parasitemias and high mortality, in sharp contrast with the reduced infectivity in vitro. Upon recovery from the mouse stomach 1h after oral inoculation, the gp90 molecule of the parasites was completely degraded, and their entry into HeLa cells, as well as into Caco-2 cells, was increased. The gp82 molecule was more resistant to digestive action of the gastric juice. Host cell invasion of SC isolate metacyclic trypomastigotes was augmented in the presence of gastric mucin. No alteration in infectivity was observed in T. cruzi strains CL and G which were used as references and which express gp90 molecules resistant to degradation by gastric juice. Taken together, our findings suggest that the exacerbation of T. cruzi infectivity, such as observed upon interaction of the SC isolate with the mouse stomach components, may be responsible for the severity of acute Chagas' disease that has been reported in outbreaks of oral T. cruzi infection.

  2. Induction of Central Host Signaling Kinases during Pneumococcal Infection of Human THP-1 Cells

    PubMed Central

    Kohler, Thomas P.; Scholz, Annemarie; Kiachludis, Delia; Hammerschmidt, Sven

    2016-01-01

    bacterial uptake. The participation of essential host cell signaling kinases in pneumococcal phagocytosis was deciphered for the kinase Akt, ERK1/2, and p38 and phosphoimmunoblots showed an increased phosphorylation and thus activation upon infection with pneumococci. Taken together, this study deciphers host cell kinases in innate immune cells that are induced upon infection with pneumococci and interfere with bacterial clearance after phagocytosis. PMID:27200303

  3. Genomic Modifiers of Natural Killer Cells, Immune Responsiveness and Lymphoid Tissue Remodeling Together Increase Host Resistance to Viral Infection.

    PubMed

    Gillespie, Alyssa Lundgren; Teoh, Jeffrey; Lee, Heather; Prince, Jessica; Stadnisky, Michael D; Anderson, Monique; Nash, William; Rival, Claudia; Wei, Hairong; Gamache, Awndre; Farber, Charles R; Tung, Kenneth; Brown, Michael G

    2016-02-01

    The MHC class I D(k) molecule supplies vital host resistance during murine cytomegalovirus (MCMV) infection. Natural killer (NK) cells expressing the Ly49G2 inhibitory receptor, which specifically binds D(k), are required to control viral spread. The extent of D(k)-dependent host resistance, however, differs significantly amongst related strains of mice, C57L and MA/My. As a result, we predicted that relatively small-effect modifier genetic loci might together shape immune cell features, NK cell reactivity, and the host immune response to MCMV. A robust D(k)-dependent genetic effect, however, has so far hindered attempts to identify additional host resistance factors. Thus, we applied genomic mapping strategies and multicolor flow cytometric analysis of immune cells in naive and virus-infected hosts to identify genetic modifiers of the host immune response to MCMV. We discovered and validated many quantitative trait loci (QTL); these were mapped to at least 19 positions on 16 chromosomes. Intriguingly, one newly discovered non-MHC locus (Cmv5) controlled splenic NK cell accrual, secondary lymphoid organ structure, and lymphoid follicle development during MCMV infection. We infer that Cmv5 aids host resistance to MCMV infection by expanding NK cells needed to preserve and protect essential tissue structural elements, to enhance lymphoid remodeling and to increase viral clearance in spleen. PMID:26845690

  4. Genomic Modifiers of Natural Killer Cells, Immune Responsiveness and Lymphoid Tissue Remodeling Together Increase Host Resistance to Viral Infection.

    PubMed

    Gillespie, Alyssa Lundgren; Teoh, Jeffrey; Lee, Heather; Prince, Jessica; Stadnisky, Michael D; Anderson, Monique; Nash, William; Rival, Claudia; Wei, Hairong; Gamache, Awndre; Farber, Charles R; Tung, Kenneth; Brown, Michael G

    2016-02-01

    The MHC class I D(k) molecule supplies vital host resistance during murine cytomegalovirus (MCMV) infection. Natural killer (NK) cells expressing the Ly49G2 inhibitory receptor, which specifically binds D(k), are required to control viral spread. The extent of D(k)-dependent host resistance, however, differs significantly amongst related strains of mice, C57L and MA/My. As a result, we predicted that relatively small-effect modifier genetic loci might together shape immune cell features, NK cell reactivity, and the host immune response to MCMV. A robust D(k)-dependent genetic effect, however, has so far hindered attempts to identify additional host resistance factors. Thus, we applied genomic mapping strategies and multicolor flow cytometric analysis of immune cells in naive and virus-infected hosts to identify genetic modifiers of the host immune response to MCMV. We discovered and validated many quantitative trait loci (QTL); these were mapped to at least 19 positions on 16 chromosomes. Intriguingly, one newly discovered non-MHC locus (Cmv5) controlled splenic NK cell accrual, secondary lymphoid organ structure, and lymphoid follicle development during MCMV infection. We infer that Cmv5 aids host resistance to MCMV infection by expanding NK cells needed to preserve and protect essential tissue structural elements, to enhance lymphoid remodeling and to increase viral clearance in spleen.

  5. Rickettsia typhi Possesses Phospholipase A2 Enzymes that Are Involved in Infection of Host Cells

    PubMed Central

    Rahman, M. Sayeedur; Gillespie, Joseph J.; Kaur, Simran Jeet; Sears, Khandra T.; Ceraul, Shane M.; Beier-Sexton, Magda; Azad, Abdu F.

    2013-01-01

    The long-standing proposal that phospholipase A2 (PLA2) enzymes are involved in rickettsial infection of host cells has been given support by the recent characterization of a patatin phospholipase (Pat2) with PLA2 activity from the pathogens Rickettsia prowazekii and R. typhi. However, pat2 is not encoded in all Rickettsia genomes; yet another uncharacterized patatin (Pat1) is indeed ubiquitous. Here, evolutionary analysis of both patatins across 46 Rickettsia genomes revealed 1) pat1 and pat2 loci are syntenic across all genomes, 2) both Pat1 and Pat2 do not contain predicted Sec-dependent signal sequences, 3) pat2 has been pseudogenized multiple times in rickettsial evolution, and 4) ubiquitous pat1 forms two divergent groups (pat1A and pat1B) with strong evidence for recombination between pat1B and plasmid-encoded homologs. In light of these findings, we extended the characterization of R. typhi Pat1 and Pat2 proteins and determined their role in the infection process. As previously demonstrated for Pat2, we determined that 1) Pat1 is expressed and secreted into the host cytoplasm during R. typhi infection, 2) expression of recombinant Pat1 is cytotoxic to yeast cells, 3) recombinant Pat1 possesses PLA2 activity that requires a host cofactor, and 4) both Pat1 cytotoxicity and PLA2 activity were reduced by PLA2 inhibitors and abolished by site-directed mutagenesis of catalytic Ser/Asp residues. To ascertain the role of Pat1 and Pat2 in R. typhi infection, antibodies to both proteins were used to pretreat rickettsiae. Subsequent invasion and plaque assays both indicated a significant decrease in R. typhi infection compared to that by pre-immune IgG. Furthermore, antibody-pretreatment of R. typhi blocked/delayed phagosomal escapes. Together, these data suggest both enzymes are involved early in the infection process. Collectively, our study suggests that R. typhi utilizes two evolutionary divergent patatin phospholipases to support its intracellular life cycle, a

  6. Transcriptional analysis of Rickettsia prowazekii invasion gene homolog (invA) during host cell infection.

    PubMed

    Gaywee, Jariyanart; Radulovic, Suzana; Higgins, James A; Azad, Abdu F

    2002-11-01

    An invasion gene homolog, invA, of Rickettsia prowazekii has recently been identified to encode a member of the Nudix hydrolase subfamily which acts specifically on dinucleoside oligophosphates (Np(n)N; n >/= 5), a group of cellular signaling molecules known as alarmones. InvA is thought to enhance intracellular survival by regulating stress-induced toxic nucleotide levels during rickettsial infection. To further characterize the physiological function of InvA, the gene expression pattern during various stages of rickettsial intracellular growth was investigated. Using semiquantitative reverse transcription-PCR (RT-PCR) and real-time fluorescent probe-based quantitative RT-PCR, a differential expression profile of invA during rickettsial host cell infection was examined. The invA transcript temporarily increased during the early period of infection. Expression of rickettsial groEL, a molecular indicator of cellular stresses, was also shown to be upregulated during the early period of infection. Furthermore, invA was cotranscribed in a polycistronic message with rrp, a gene encoding the response regulator protein homolog, which is a part of a two-component signal transduction system. These results support our earlier findings that under such stress conditions dinucleoside oligophosphate pyrophosphatase may function as a buffer, enhancing rickettsial survival within the cytoplasm of a eukaryotic cell. The expression of rickettsial dinucleoside oligophosphate pyrophosphatase may be regulated by a part of the two-component signal transduction system similar to that described for response regulators in other bacterial systems.

  7. Over-expression and localization of a host protein on the membrane of Cryptosporidium parvum infected epithelial cells.

    PubMed

    Yang, Yi-Lin; Serrano, Myrna G; Sheoran, Abhineet S; Manque, Patricio A; Buck, Gregory A; Widmer, Giovanni

    2009-11-01

    The genus Cryptosporidium includes several species of intestinal protozoan parasites which multiply in intestinal epithelial cells. The impact of this infection on the transcriptome of cultured host cells was investigated using DNA microarray hybridizations. The expression of 14 genes found to be consistently up- or down-regulated in infected cell monolayers was validated with RT PCR. Using immunofluorescence we examined the expression of Protease Activated Receptor-2, which is encoded by one of the up-regulated genes. In infected cells this receptor localized to the host cell membrane which covers the intracellular trophozoites and meronts. This observation indicates that the composition of the host cell membrane is affected by the developing trophozoite, a phenomenon which has not been described previously.

  8. Over-expression and localization of a host protein on the membrane of Cryptosporidium parvum infected epithelial cells

    PubMed Central

    Yang, Yi-Lin; Serrano, Myrna G.; Sheoran, Abhineet S.; Manque, Patricio A.; Buck, Gregory A.; Widmer, Giovanni

    2009-01-01

    The genus Cryptosporidium includes several species of intestinal protozoan parasites which multiply in intestinal epithelial cells. The impact of this infection on the transcriptome of cultured host cells was investigated using DNA microarray hybridizations. The expression of 14 genes found to be consistently up- or down-regulated in infected cell monolayers was validated with RT PCR. Using immunofluorescence we examined the expression of Protease Activated Receptor-2, which is encoded by one of the up-regulated genes. In infected cells this receptor localized to the host cell membrane which covers intracellular trophozoites and meronts. This observation indicates that the composition of the host cell membrane is affected by the developing trophozoite, a phenomenon which has not been described previously. PMID:19631240

  9. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes.

    PubMed

    Sherling, Emma S; van Ooij, Christiaan

    2016-09-01

    Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. PMID:27587718

  10. Host cell remodeling by pathogens: the exomembrane system in Plasmodium-infected erythrocytes

    PubMed Central

    Sherling, Emma S.; van Ooij, Christiaan

    2016-01-01

    Malaria is caused by infection of erythrocytes by parasites of the genus Plasmodium. To survive inside erythrocytes, these parasites induce sweeping changes within the host cell, one of the most dramatic of which is the formation of multiple membranous compartments, collectively referred to as the exomembrane system. As an uninfected mammalian erythrocyte is devoid of internal membranes, the parasite must be the force and the source behind the formation of these compartments. Even though the first evidence of the presence these of internal compartments was obtained over a century ago, their functions remain mostly unclear, and in some cases completely unknown, and the mechanisms underlying their formation are still mysterious. In this review, we provide an overview of the different parts of the exomembrane system, describing the parasitophorous vacuole, the tubovesicular network, Maurer's clefts, the caveola-vesicle complex, J dots and other mobile compartments, and the small vesicles that have been observed in Plasmodium-infected cells. Finally, we combine the data into a simplified view of the exomembrane system and its relation to the alterations of the host erythrocyte. PMID:27587718

  11. A pathogenic long noncoding RNA redesigns the epigenetic landscape of the infected cells by subverting host Histone Deacetylase 6 activity.

    PubMed

    Castellano, Mayte; Pallas, Vicente; Gomez, Gustavo

    2016-09-01

    Viroids - ancient plant-pathogenic long noncoding RNAs - have developed a singular evolutionary strategy based on reprogramming specific phases of host-metabolism to ensure that their infection cycle can be completed in infected cells. However, the molecular aspects governing this transregulatory phenomenon remain elusive. Here, we use immunoprecipitation assays and bisulfite sequencing of rDNA to shown that, in infected cucumber and Nicotiana benthamina plants, Hop stunt viroid (HSVd) recruits and functionally subverts Histone Deacetylase 6 (HDA6) to promote host-epigenetic alterations that trigger the transcriptional alterations observed during viroid pathogenesis. This notion is supported by the demonstration that, during infection, the HSVd-HDA6 complex occurs in vivo and that endogenous HDA6 expression is increased in HSVd-infected cells. Moreover, transient overexpression of recombinant HDA6 reverts the hypomethylation status of rDNA observed in HSVd-infected plants and reduces viroid accumulation. We hypothesize that the host-transcriptional alterations induced as a consequence of viroid-mediated HDA6 recruitment favor spurious recognition of HSVd-RNA as an RNA Pol II template, thereby improving viroid replication. Our results constitute the first description of a physical and functional interaction between a pathogenic RNA and a component of the host RNA silencing mechanism, providing novel evidence of the potential of these pathogenic lncRNAs to physically redesign the host-cell environment and reprogram their regulatory mechanisms. PMID:27174164

  12. Microscopy-based Assays for High-throughput Screening of Host Factors Involved in Brucella Infection of Hela Cells.

    PubMed

    Casanova, Alain; Low, Shyan H; Emmenlauer, Mario; Conde-Alvarez, Raquel; Salcedo, Suzana P; Gorvel, Jean-Pierre; Dehio, Christoph

    2016-01-01

    Brucella species are facultative intracellular pathogens that infect animals as their natural hosts. Transmission to humans is most commonly caused by direct contact with infected animals or by ingestion of contaminated food and can lead to severe chronic infections. Brucella can invade professional and non-professional phagocytic cells and replicates within endoplasmic reticulum (ER)-derived vacuoles. The host factors required for Brucella entry into host cells, avoidance of lysosomal degradation, and replication in the ER-like compartment remain largely unknown. Here we describe two assays to identify host factors involved in Brucella entry and replication in HeLa cells. The protocols describe the use of RNA interference, while alternative screening methods could be applied. The assays are based on the detection of fluorescently labeled bacteria in fluorescently labeled host cells using automated wide-field microscopy. The fluorescent images are analyzed using a standardized image analysis pipeline in CellProfiler which allows single cell-based infection scoring. In the endpoint assay, intracellular replication is measured two days after infection. This allows bacteria to traffic to their replicative niche where proliferation is initiated around 12 hr after bacterial entry. Brucella which have successfully established an intracellular niche will thus have strongly proliferated inside host cells. Since intracellular bacteria will greatly outnumber individual extracellular or intracellular non-replicative bacteria, a strain constitutively expressing GFP can be used. The strong GFP signal is then used to identify infected cells. In contrast, for the entry assay it is essential to differentiate between intracellular and extracellular bacteria. Here, a strain encoding for a tetracycline-inducible GFP is used. Induction of GFP with simultaneous inactivation of extracellular bacteria by gentamicin enables the differentiation between intracellular and extracellular

  13. An in vitro model of granuloma-like cell aggregates substantiates early host immune responses against Mycobacterium massiliense infection

    PubMed Central

    Je, Sungmo; Quan, Hailian; Na, Yirang; Cho, Sang-Nae; Kim, Bum-Joon

    2016-01-01

    ABSTRACT Mycobacterium massiliense (M. mass), belonging to the M. abscessus complex, is a rapidly growing mycobacterium that is known to cause tuberculous-like lesions in humans. To better understand the interaction between host cells and M. mass, we used a recently developed in vitro model of early granuloma-like cell aggregates composed of human peripheral blood mononuclear cells (PBMCs). PBMCs formed granuloma-like, small and rounded cell aggregates when infected by live M. mass. Microscopic examination showed monocytes and macrophages surrounded by lymphocytes, which resembled cell aggregation induced by M. tuberculosis (M. tb). M. mass-infected PBMCs exhibited higher expression levels of HLA-DR, CD86 and CD80 on macrophages, and a significant decrease in the populations of CD4+ and CD8+ T cells. Interestingly, low doses of M. mass were sufficient to infect PBMCs, while active host cell death was gradually induced with highly increased bacterial loads, reflecting host destruction and dissemination of virulent rapid-growing mycobacteria (RGM). Collectively, this in vitro model of M. mass infection improves our understanding of the interplay of host immune cells with mycobacteria, and may be useful for developing therapeutics to control bacterial pathogenesis. PMID:27489303

  14. Proteomics analysis of EV71-infected cells reveals the involvement of host protein NEDD4L in EV71 replication.

    PubMed

    Kuo, Rei-Lin; Lin, Ya-Han; Wang, Robert Yung-Liang; Hsu, Chia-Wei; Chiu, Yi-Ting; Huang, Hsing-I; Kao, Li-Ting; Yu, Jau-Song; Shih, Shin-Ru; Wu, Chih-Ching

    2015-04-01

    Enterovirus 71 (EV71) is a human enterovirus that has seriously affected the Asia-Pacific area for the past two decades. EV71 infection can result in mild hand-foot-and-mouth disease and herpangina and may occasionally lead to severe neurological complications in children. However, the specific biological processes that become altered during EV71 infection remain unclear. To further explore host responses upon EV71 infection, we identified proteins differentially expressed in EV71-infected human glioblastoma SF268 cells using isobaric mass tag (iTRAQ) labeling coupled with multidimensional liquid chromatography-mass spectrometry (LC-MS/MS). Network analysis of proteins altered in cells infected with EV71 revealed that the changed biological processes are related to protein and ion transport, regulation of protein degradation, and homeostatic processes. We confirmed that the levels of NEDD4L and PSMF1 were increased and reduced, respectively, in EV71-infected cells compared to mock-infected control cells. To determine the physiological relevance of our findings, we investigated the consequences of EV71 infection in cells with NEDD4L or PSMF1 depletion. We found that the depletion of NEDD4L significantly reduced the replication of EV71, whereas PSMF1 knockdown enhanced EV71 replication. Collectively, our findings provide the first evidence of proteome-wide dysregulation by EV71 infection and suggest a novel role for the host protein NEDD4L in the replication of this virus.

  15. Modulation of Cell Sialoglycophenotype: A Stylish Mechanism Adopted by Trypanosoma cruzi to Ensure Its Persistence in the Infected Host

    PubMed Central

    Freire-de-Lima, Leonardo; da Fonseca, Leonardo M.; da Silva, Vanessa A.; da Costa, Kelli M.; Morrot, Alexandre; Freire-de-Lima, Célio G.; Previato, Jose O.; Mendonça-Previato, Lucia

    2016-01-01

    Trypanosoma cruzi, the etiological agent of Chagas disease exhibits multiple mechanisms to guarantee its establishment and persistence in the infected host. It has been well demonstrated that T. cruzi is not able to synthesize sialic acids (Sia). To acquire the monosaccharide, the parasite makes use of a multifunctional enzyme called trans-sialidase (Tc-TS). Since this enzyme has no analogous in the vertebrate host, it has been used as a target in drug therapy development. Tc-TS preferentially catalyzes the transfer of Sia from the host glycoconjugates to the terminal β-galactopyranosyl residues of mucin-like molecules present on the parasite’s cell surface. Alternatively, the enzyme can sialylate/re-sialylate glycoconjugates expressed on the surface of host cells. Since its discovery, several studies have shown that T. cruzi employs the Tc-TS activity to modulate the host cell sialoglycophenotype, thus favoring its perpetuation in the infected vertebrate. In this review, we summarize the dynamic of host/parasite sialoglycophenotype modulation, highlighting its role in the subversion of host immune response in order to promote the establishment of persistent chronic infection. PMID:27242722

  16. The Influence of Virus Infection on the Extracellular pH of the Host Cell Detected on Cell Membrane

    PubMed Central

    Liu, Hengjun; Maruyama, Hisataka; Masuda, Taisuke; Honda, Ayae; Arai, Fumihito

    2016-01-01

    Influenza virus infection can result in changes in the cellular ion levels at 2–3 h post-infection. More H+ is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H+ during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H+ from the intracellular compartment. Increased H+ export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (ϕ1 μm) containing Rhodamine B and Fluorescein isothiocyanate (FITC). The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5–0.6 in 4 h after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 protein in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 protein are detected in virus-unbound cells where the extracellular pH remained constant. PMID:27582727

  17. The Influence of Virus Infection on the Extracellular pH of the Host Cell Detected on Cell Membrane.

    PubMed

    Liu, Hengjun; Maruyama, Hisataka; Masuda, Taisuke; Honda, Ayae; Arai, Fumihito

    2016-01-01

    Influenza virus infection can result in changes in the cellular ion levels at 2-3 h post-infection. More H(+) is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H(+) during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H(+) from the intracellular compartment. Increased H(+) export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (ϕ1 μm) containing Rhodamine B and Fluorescein isothiocyanate (FITC). The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5-0.6 in 4 h after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 protein in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 protein are detected in virus-unbound cells where the extracellular pH remained constant. PMID:27582727

  18. Cell adhesion molecules in the pathogenesis of and host defence against microbial infection.

    PubMed Central

    Kerr, J R

    1999-01-01

    Eukaryotic cell adhesion molecules (CAMs) are used by various cells and extracellular molecules in host defence against infection. They are involved in many processes including recognition by circulating phagocytes of a site of inflammation, transmigration through the endothelial barrier, diapedesis through basement membrane and extracellular matrix, and release of effector mechanisms at the infected site. CAMs involved in leucocyte-endothelial cell interaction include the selectins, integrins, and members of the immunoglobulin superfamily. However, CAMs are also used by various microorganisms (protozoa, fungi, bacteria, and viruses) during their pathogenesis. For example, bacteria that utilise CAMs include Mycobacterium tuberculosis, Listeria monocytogenes, Yersinia spp, enteropathogenic Escherichia coli, Shigella spp, Neisseria spp, Bordetella spp, and Borrelia burgdorferi. In addition, CAMs are involved in the pathogenetic effects of the RTX toxins of Pasteurella haemolytica, Actinobacillus actinomycetemcomitans, and the superantigen exotoxins of Staphylococcus aureus and Streptococcus pyogenes. A recurrent and topical theme of potential importance within the bacterial group is the intimate relation between CAMs, bacterial protein receptors, and type III secretion systems. For example, the IpaBCD protein complex is secreted by the type III system of Shigella flexneri and interacts with alpha 5 beta 1 integrin on the eukaryotic cell surface, followed by Rho mediated internalisation; this illustrates the relevance of cellular microbiology. CAMs might prove to be novel therapeutic targets. Comparative genomics has provided the knowledge of shared virulence determinants among diverse bacterial genera, and will continue to deepen our understanding of microbial pathogenesis, particularly in the context of the interaction of prokaryotic and eukaryotic molecules. PMID:10694943

  19. Differences between Mycobacterium-Host Cell Relationships in Latent Tuberculous Infection of Mice Ex Vivo and Mycobacterial Infection of Mouse Cells In Vitro

    PubMed Central

    Ufimtseva, Elena

    2016-01-01

    The search for factors that account for the reproduction and survival of mycobacteria, including vaccine strains, in host cells is the priority for studies on tuberculosis. A comparison of BCG-mycobacterial loads in granuloma cells obtained from bone marrow and spleens of mice with latent tuberculous infection and cells from mouse bone marrow and peritoneal macrophage cultures infected with the BCG vaccine in vitro has demonstrated that granuloma macrophages each normally contained a single BCG-Mycobacterium, while those acutely infected in vitro had increased mycobacterial loads and death rates. Mouse granuloma cells were observed to produce the IFNγ, IL-1α, GM-CSF, CD1d, CD25, CD31, СD35, and S100 proteins. None of these activation markers were found in mouse cell cultures infected in vitro or in intact macrophages. Lack of colocalization of lipoarabinomannan-labeled BCG-mycobacteria with the lysosomotropic LysoTracker dye in activated granuloma macrophages suggests that these macrophages were unable to destroy BCG-mycobacteria. However, activated mouse granuloma macrophages could control mycobacterial reproduction in cells both in vivo and in ex vivo culture. By contrast, a considerable increase in the number of BCG-mycobacteria was observed in mouse bone marrow and peritoneal macrophages after BCG infection in vitro, when no expression of the activation-related molecules was detected in these cells. PMID:27066505

  20. A Tale of Two RNAs during Viral Infection: How Viruses Antagonize mRNAs and Small Non-Coding RNAs in The Host Cell

    PubMed Central

    Herbert, Kristina M.; Nag, Anita

    2016-01-01

    Viral infection initiates an array of changes in host gene expression. Many viruses dampen host protein expression and attempt to evade the host anti-viral defense machinery. Host gene expression is suppressed at several stages of host messenger RNA (mRNA) formation including selective degradation of translationally competent messenger RNAs. Besides mRNAs, host cells also express a variety of noncoding RNAs, including small RNAs, that may also be subject to inhibition upon viral infection. In this review we focused on different ways viruses antagonize coding and noncoding RNAs in the host cell to its advantage. PMID:27271653

  1. Bst1 is required for Candida albicans infecting host via facilitating cell wall anchorage of Glycosylphosphatidyl inositol anchored proteins

    PubMed Central

    Liu, Wei; Zou, Zui; Huang, Xin; Shen, Hui; He, Li Juan; Chen, Si Min; Li, Li Ping; Yan, Lan; Zhang, Shi Qun; Zhang, Jun Dong; Xu, Zheng; Xu, Guo Tong; An, Mao Mao; Jiang, Yuan Ying

    2016-01-01

    Glycosylphosphatidyl inositol anchored proteins (GPI-APs) on fungal cell wall are essential for invasive infections. While the function of inositol deacylation of GPI-APs in mammalian cells has been previously characterized the impact of inositol deacylation in fungi and implications to host infection remains largely unexplored. Herein we describe our identification of BST1, an inositol deacylase of GPI-Aps in Candida albicans, was critical for GPI-APs cell wall attachment and host infection. BST1-deficient C. albicans (bst1Δ/Δ) was associated with severely impaired cell wall anchorage of GPI-APs and subsequen unmasked β-(1,3)-glucan. Consistent with the aberrant cell wall structures, bst1Δ/Δ strain did not display an invasive ability and could be recognized more efficiently by host immune systems. Moreover, BST1 null mutants or those expressing Bst1 variants did not display inositol deacylation activity and exhibited severely attenuated virulence and reduced organic colonization in a murine systemic candidiasis model. Thus, Bst1 can facilitate cell wall anchorage of GPI-APs in C. albicans by inositol deacylation, and is critical for host invasion and immune escape. PMID:27708385

  2. Arginine decarboxylase inhibitors reduce the capacity of Trypanosoma cruzi to infect and multiply in mammalian host cells.

    PubMed Central

    Kierszenbaum, F; Wirth, J J; McCann, P P; Sjoerdsma, A

    1987-01-01

    The capacity of blood (trypomastigote) forms of Trypanosoma cruzi to infect mouse peritoneal macrophages or rat heart myoblasts in vitro was inhibited by treatment of the trypomastigotes with DL-alpha-difluoromethylarginine (F2Me Arg), monofluoromethylagmatine, or (E)-alpha-monofluoromethyl-3-4-dehydroarginine--all irreversible inhibitors of arginine decarboxylase. Similar results were obtained when F2MeArg-treated parasites were incubated with rat heart myoblasts. The inhibitory effects were characterized by marked reductions in both the proportion of infected cells and the number of parasites per 100 host cells. The concentrations of the arginine decarboxylase inhibitors that affected infectivity had no detectable effect on either the concentration or motility of the parasite and, therefore, could not have affected the collision frequency. F2MeArg appeared to inhibit the ability of T. cruzi to penetrate the host cells since the drug had no significant effect on the extent of parasite binding to the surface of the host cells. The inhibitory effect of F2MeArg was markedly reduced or abrogated in the presence of either agmatine or putrescine, as would have been expected if F2MeArg acted by inhibiting arginine decarboxylase. Addition of F2MeArg to macrophage or myoblast cultures immediately after infection or at a time when virtually all of the intracellular parasites had transformed into the multiplicative amastigote form, resulted in a markedly reduced parasite growth rate. This effect was also prevented by exogenous agmatine. These results indicate the importance of polyamines and polyamine biosynthesis in the following two important functions of T. cruzi: invasion of host cells and intracellular multiplication. Furthermore, concentrations of the inhibitors tested that affected the parasite did not alter the viability of the host cells, the cellular density of the cultures, or the ability of uninfected myoblasts to grow. Thus, arginine decarboxylase inhibitors may

  3. Afatinib Reduces STAT6 Signaling of Host ARPE-19 Cells Infected with Toxoplasma gondii

    PubMed Central

    Yang, Zhaoshou; Ahn, Hye-Jin; Park, Young-Hoon; Nam, Ho-Woo

    2016-01-01

    Specific gene expressions of host cells by spontaneous STAT6 phosphorylation are major strategy for the survival of intracellular Toxoplasma gondii against parasiticidal events through STAT1 phosphorylation by infection provoked IFN-γ. We determined the effects of small molecules of tyrosine kinase inhibitors (TKIs) on the growth of T. gondii and on the relationship with STAT1 and STAT6 phosphorylation in ARPE-19 cells. We counted the number of T. gondii RH tachyzoites per parasitophorous vacuolar membrane (PVM) after treatment with TKIs at 12-hr intervals for 72 hr. The change of STAT6 phosphorylation was assessed via western blot and immunofluorescence assay. Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, 5 µM) inhibited 98.0% of the growth of T. gondii, which was comparable to pyrimethamine (5 µM) at 96.9% and followed by Erlotinib (ErbB1/EGFR inhibitor, 20 µM) at 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, 10 µM) at 21.3%. In the early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibited the phosphorylation of STAT6 in western blot and immunofluorescence assay. Both JAK1 and JAK3, the upper hierarchical kinases of cytokine signaling, were strongly phosphorylated at 2 hr and then disappeared entirely after 4 hr. Some TKIs, especially the EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of the direct phosphorylation of STAT6 by T. gondii. PMID:26951976

  4. Staphylococcus aureus-Induced G2/M Phase Transition Delay in Host Epithelial Cells Increases Bacterial Infective Efficiency

    PubMed Central

    Almeida, Sintia; Legembre, Patrick; Edmond, Valérie; Azevedo, Vasco; Miyoshi, Anderson; Even, Sergine; Taieb, Frédéric; Arlot-Bonnemains, Yannick; Le Loir, Yves; Berkova, Nadia

    2013-01-01

    Staphylococcus aureus is a highly versatile, opportunistic pathogen and the etiological agent of a wide range of infections in humans and warm-blooded animals. The epithelial surface is its principal site of colonization and infection. In this work, we investigated the cytopathic effect of S. aureus strains from human and animal origins and their ability to affect the host cell cycle in human HeLa and bovine MAC-T epithelial cell lines. S. aureus invasion slowed down cell proliferation and induced a cytopathic effect, resulting in the enlargement of host cells. A dramatic decrease in the number of mitotic cells was observed in the infected cultures. Flow cytometry analysis revealed an S. aureus-induced delay in the G2/M phase transition in synchronous HeLa cells. This delay required the presence of live S. aureus since the addition of the heat-killed bacteria did not alter the cell cycle. The results of Western blot experiments showed that the G2/M transition delay was associated with the accumulation of inactive cyclin-dependent kinase Cdk1, a key inducer of mitosis entry, and with the accumulation of unphosphorylated histone H3, which was correlated with a reduction of the mitotic cell number. Analysis of S. aureus proliferation in asynchronous, G1- and G2-phase-enriched HeLa cells showed that the G2 phase was preferential for bacterial infective efficiency, suggesting that the G2 phase delay may be used by S. aureus for propagation within the host. Taken together, our results divulge the potential of S. aureus in the subversion of key cellular processes such as cell cycle progression, and shed light on the biological significance of S. aureus-induced host cell cycle alteration. PMID:23717407

  5. Staphylococcus aureus-induced G2/M phase transition delay in host epithelial cells increases bacterial infective efficiency.

    PubMed

    Alekseeva, Ludmila; Rault, Lucie; Almeida, Sintia; Legembre, Patrick; Edmond, Valérie; Azevedo, Vasco; Miyoshi, Anderson; Even, Sergine; Taieb, Frédéric; Arlot-Bonnemains, Yannick; Le Loir, Yves; Berkova, Nadia

    2013-01-01

    Staphylococcus aureus is a highly versatile, opportunistic pathogen and the etiological agent of a wide range of infections in humans and warm-blooded animals. The epithelial surface is its principal site of colonization and infection. In this work, we investigated the cytopathic effect of S. aureus strains from human and animal origins and their ability to affect the host cell cycle in human HeLa and bovine MAC-T epithelial cell lines. S. aureus invasion slowed down cell proliferation and induced a cytopathic effect, resulting in the enlargement of host cells. A dramatic decrease in the number of mitotic cells was observed in the infected cultures. Flow cytometry analysis revealed an S. aureus-induced delay in the G2/M phase transition in synchronous HeLa cells. This delay required the presence of live S. aureus since the addition of the heat-killed bacteria did not alter the cell cycle. The results of Western blot experiments showed that the G2/M transition delay was associated with the accumulation of inactive cyclin-dependent kinase Cdk1, a key inducer of mitosis entry, and with the accumulation of unphosphorylated histone H3, which was correlated with a reduction of the mitotic cell number. Analysis of S. aureus proliferation in asynchronous, G1- and G2-phase-enriched HeLa cells showed that the G2 phase was preferential for bacterial infective efficiency, suggesting that the G2 phase delay may be used by S. aureus for propagation within the host. Taken together, our results divulge the potential of S. aureus in the subversion of key cellular processes such as cell cycle progression, and shed light on the biological significance of S. aureus-induced host cell cycle alteration.

  6. Comparison of host cell gene expression in cowpox, monkeypox or vaccinia virus-infected cells reveals virus-specific regulation of immune response genes

    PubMed Central

    2013-01-01

    Background Animal-borne orthopoxviruses, like monkeypox, vaccinia and the closely related cowpox virus, are all capable of causing zoonotic infections in humans, representing a potential threat to human health. The disease caused by each virus differs in terms of symptoms and severity, but little is yet know about the reasons for these varying phenotypes. They may be explained by the unique repertoire of immune and host cell modulating factors encoded by each virus. In this study, we analysed the specific modulation of the host cell’s gene expression profile by cowpox, monkeypox and vaccinia virus infection. We aimed to identify mechanisms that are either common to orthopoxvirus infection or specific to certain orthopoxvirus species, allowing a more detailed description of differences in virus-host cell interactions between individual orthopoxviruses. To this end, we analysed changes in host cell gene expression of HeLa cells in response to infection with cowpox, monkeypox and vaccinia virus, using whole-genome gene expression microarrays, and compared these to each other and to non-infected cells. Results Despite a dominating non-responsiveness of cellular transcription towards orthopoxvirus infection, we could identify several clusters of infection-modulated genes. These clusters are either commonly regulated by orthopoxvirus infection or are uniquely regulated by infection with a specific orthopoxvirus, with major differences being observed in immune response genes. Most noticeable was an induction of genes involved in leukocyte migration and activation in cowpox and monkeypox virus-infected cells, which was not observed following vaccinia virus infection. Conclusion Despite their close genetic relationship, the expression profiles induced by infection with different orthopoxviruses vary significantly. It may be speculated that these differences at the cellular level contribute to the individual characteristics of cowpox, monkeypox and vaccinia virus

  7. Global transcriptional analysis of model of persistent FMDV infection reveals critical role of host cells in persistence.

    PubMed

    Zhang, Hu; Li, Yong; Huang, Xuan; Zheng, Congyi

    2013-03-23

    With the aid of ammonium chloride, we established a model for persistent foot-and-mouth disease virus (FMDV) infection of BHK-21 cells (Huang et al., 2011). Distinctive to a previously established model, the persistently infected cell line acquired new features including more rounded morphology, resistance to wild type FMDV infection, consistent replication efficiency in late passages, etc. To elucidate the mechanism of establishment of persistence, we performed systematically microarray analysis of gene expression profiles of acute and persistent infections and real-time quantitative PCR validation of key genes. Our results showed 12 common genes were found to be up-regulated in acute infection while down-regulated in persistent infection. Gene expression analysis indicated differences in the KEGG pathway, revealing important roles of host factors in the maintenance of symbiotic environment. The results suggest that, in contrast to previous viral persistence system, the critical element in establishment of the persistence in our lab is the evolution of host cells which regulate genome transcription to defy the lytic effects of FMDV infection. PMID:23022682

  8. Virus-host interactions in persistently FMDV-infected cells derived from bovine pharynx

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foot-and-mouth disease virus (FMDV) produces a disease in cattle characterized by vesicular lesions and a persistent infection with asymptomatic low-level production of virus. Here we describe the establishment of a persistently infected primary cell culture derived from bovine pharynx tissue (PBPT)...

  9. Nuclease Activity of Legionella pneumophila Cas2 Promotes Intracellular Infection of Amoebal Host Cells

    PubMed Central

    Gunderson, Felizza F.; Mallama, Celeste A.; Fairbairn, Stephanie G.

    2014-01-01

    Legionella pneumophila, the primary agent of Legionnaires' disease, flourishes in both natural and man-made environments by growing in a wide variety of aquatic amoebae. Recently, we determined that the Cas2 protein of L. pneumophila promotes intracellular infection of Acanthamoeba castellanii and Hartmannella vermiformis, the two amoebae most commonly linked to cases of disease. The Cas2 family of proteins is best known for its role in the bacterial and archeal clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated protein (Cas) system that constitutes a form of adaptive immunity against phage and plasmid. However, the infection event mediated by L. pneumophila Cas2 appeared to be distinct from this function, because cas2 mutants exhibited infectivity defects in the absence of added phage or plasmid and since mutants lacking the CRISPR array or any one of the other cas genes were not impaired in infection ability. We now report that the Cas2 protein of L. pneumophila has both RNase and DNase activities, with the RNase activity being more pronounced. By characterizing a catalytically deficient version of Cas2, we determined that nuclease activity is critical for promoting infection of amoebae. Also, introduction of Cas2, but not its catalytic mutant form, into a strain of L. pneumophila that naturally lacks a CRISPR-Cas locus caused that strain to be 40- to 80-fold more infective for amoebae, unequivocally demonstrating that Cas2 facilitates the infection process independently of any other component encoded within the CRISPR-Cas locus. Finally, a cas2 mutant was impaired for infection of Willaertia magna but not Naegleria lovaniensis, suggesting that Cas2 promotes infection of most but not all amoebal hosts. PMID:25547789

  10. Identification of RNA Binding Proteins Associated with Dengue Virus RNA in Infected Cells Reveals Temporally Distinct Host Factor Requirements

    PubMed Central

    Viktorovskaya, Olga V.; Greco, Todd M.; Cristea, Ileana M.; Thompson, Sunnie R.

    2016-01-01

    Background There are currently no vaccines or antivirals available for dengue virus infection, which can cause dengue hemorrhagic fever and death. A better understanding of the host pathogen interaction is required to develop effective therapies to treat DENV. In particular, very little is known about how cellular RNA binding proteins interact with viral RNAs. RNAs within cells are not naked; rather they are coated with proteins that affect localization, stability, translation and (for viruses) replication. Methodology/Principal Findings Seventy-nine novel RNA binding proteins for dengue virus (DENV) were identified by cross-linking proteins to dengue viral RNA during a live infection in human cells. These cellular proteins were specific and distinct from those previously identified for poliovirus, suggesting a specialized role for these factors in DENV amplification. Knockdown of these proteins demonstrated their function as viral host factors, with evidence for some factors acting early, while others late in infection. Their requirement by DENV for efficient amplification is likely specific, since protein knockdown did not impair the cell fitness for viral amplification of an unrelated virus. The protein abundances of these host factors were not significantly altered during DENV infection, suggesting their interaction with DENV RNA was due to specific recruitment mechanisms. However, at the global proteome level, DENV altered the abundances of proteins in particular classes, including transporter proteins, which were down regulated, and proteins in the ubiquitin proteasome pathway, which were up regulated. Conclusions/Significance The method for identification of host factors described here is robust and broadly applicable to all RNA viruses, providing an avenue to determine the conserved or distinct mechanisms through which diverse viruses manage the viral RNA within cells. This study significantly increases the number of cellular factors known to interact with

  11. Absolute Quantification of the Host-To-Parasite DNA Ratio in Theileria parva-Infected Lymphocyte Cell Lines.

    PubMed

    Gotia, Hanzel T; Munro, James B; Knowles, Donald P; Daubenberger, Claudia A; Bishop, Richard P; Silva, Joana C

    2016-01-01

    Theileria parva is a tick-transmitted intracellular apicomplexan pathogen of cattle in sub-Saharan Africa that causes East Coast fever (ECF). ECF is an acute fatal disease that kills over one million cattle annually, imposing a tremendous burden on African small-holder cattle farmers. The pathology and level of T. parva infections in its wildlife host, African buffalo (Syncerus caffer), and in cattle are distinct. We have developed an absolute quantification method based on quantitative PCR (qPCR) in which recombinant plasmids containing single copy genes specific to the parasite (apical membrane antigen 1 gene, ama1) or the host (hypoxanthine phosphoribosyltransferase 1, hprt1) are used as the quantification reference standards. Our study shows that T. parva and bovine cells are present in similar numbers in T. parva-infected lymphocyte cell lines and that consequently, due to its much smaller genome size, T. parva DNA comprises between 0.9% and 3% of the total DNA samples extracted from these lines. This absolute quantification assay of parasite and host genome copy number in a sample provides a simple and reliable method of assessing T. parva load in infected bovine lymphocytes, and is accurate over a wide range of host-to-parasite DNA ratios. Knowledge of the proportion of target DNA in a sample, as enabled by this method, is essential for efficient high-throughput genome sequencing applications for a variety of intracellular pathogens. This assay will also be very useful in future studies of interactions of distinct host-T. parva stocks and to fully characterize the dynamics of ECF infection in the field. PMID:26930209

  12. Absolute Quantification of the Host-To-Parasite DNA Ratio in Theileria parva-Infected Lymphocyte Cell Lines

    PubMed Central

    Gotia, Hanzel T.; Munro, James B.; Knowles, Donald P.; Daubenberger, Claudia A.; Bishop, Richard P.; Silva, Joana C.

    2016-01-01

    Theileria parva is a tick-transmitted intracellular apicomplexan pathogen of cattle in sub-Saharan Africa that causes East Coast fever (ECF). ECF is an acute fatal disease that kills over one million cattle annually, imposing a tremendous burden on African small-holder cattle farmers. The pathology and level of T. parva infections in its wildlife host, African buffalo (Syncerus caffer), and in cattle are distinct. We have developed an absolute quantification method based on quantitative PCR (qPCR) in which recombinant plasmids containing single copy genes specific to the parasite (apical membrane antigen 1 gene, ama1) or the host (hypoxanthine phosphoribosyltransferase 1, hprt1) are used as the quantification reference standards. Our study shows that T. parva and bovine cells are present in similar numbers in T. parva-infected lymphocyte cell lines and that consequently, due to its much smaller genome size, T. parva DNA comprises between 0.9% and 3% of the total DNA samples extracted from these lines. This absolute quantification assay of parasite and host genome copy number in a sample provides a simple and reliable method of assessing T. parva load in infected bovine lymphocytes, and is accurate over a wide range of host-to-parasite DNA ratios. Knowledge of the proportion of target DNA in a sample, as enabled by this method, is essential for efficient high-throughput genome sequencing applications for a variety of intracellular pathogens. This assay will also be very useful in future studies of interactions of distinct host-T. parva stocks and to fully characterize the dynamics of ECF infection in the field. PMID:26930209

  13. Predominant role of interferon-γ in the host protective effect of CD8+ T cells against Neospora caninum infection

    PubMed Central

    Correia, Alexandra; Ferreirinha, Pedro; Botelho, Sofia; Belinha, Ana; Leitão, Catarina; Caramalho, Íris; Teixeira, Luzia; González-Fernandéz, África; Appelberg, Rui; Vilanova, Manuel

    2015-01-01

    It is well established that CD8+ T cells play an important role in protective immunity against protozoan infections. However, their role in the course of Neospora caninum infection has not been fully elucidated. Here we report that CD8-deficient mice infected with N. caninum presented higher parasitic loads in the brain and lungs and lower spleen and brain immunity-related GTPases than their wild-type counterparts. Moreover, adoptive transfer of splenic CD8+ T cells sorted from N. caninum-primed immunosufficient C57BL/10 ScSn mice prolonged the survival of infected IL-12-unresponsive C57BL/10 ScCr recipients. In both C57BL/6 and C57BL/10 ScSn mice CD8+ T cells are activated and produce interferon-γ (IFN-γ) upon challenged with N. caninum. The host protective role of IFN-γ produced by CD8+ T cells was confirmed in N. caninum-infected RAG2-deficient mice reconstituted with CD8+ T cells obtained from either IFN-γ-deficient or wild-type donors. Mice receiving IFN-γ-expressing CD8+ T cells presented lower parasitic burdens than counterparts having IFN-γ-deficient CD8+ T cells. Moreover, we observed that N. caninum-infected perforin-deficient mice presented parasitic burdens similar to those of infected wild-type controls. Altogether these results demonstrate that production of IFN-γ is a predominant protective mechanism conferred by CD8+ T cells in the course of neosporosis. PMID:26449650

  14. Predominant role of interferon-γ in the host protective effect of CD8(+) T cells against Neospora caninum infection.

    PubMed

    Correia, Alexandra; Ferreirinha, Pedro; Botelho, Sofia; Belinha, Ana; Leitão, Catarina; Caramalho, Íris; Teixeira, Luzia; González-Fernandéz, África; Appelberg, Rui; Vilanova, Manuel

    2015-10-09

    It is well established that CD8(+) T cells play an important role in protective immunity against protozoan infections. However, their role in the course of Neospora caninum infection has not been fully elucidated. Here we report that CD8-deficient mice infected with N. caninum presented higher parasitic loads in the brain and lungs and lower spleen and brain immunity-related GTPases than their wild-type counterparts. Moreover, adoptive transfer of splenic CD8(+) T cells sorted from N. caninum-primed immunosufficient C57BL/10 ScSn mice prolonged the survival of infected IL-12-unresponsive C57BL/10 ScCr recipients. In both C57BL/6 and C57BL/10 ScSn mice CD8(+) T cells are activated and produce interferon-γ (IFN-γ) upon challenged with N. caninum. The host protective role of IFN-γ produced by CD8(+) T cells was confirmed in N. caninum-infected RAG2-deficient mice reconstituted with CD8(+) T cells obtained from either IFN-γ-deficient or wild-type donors. Mice receiving IFN-γ-expressing CD8(+) T cells presented lower parasitic burdens than counterparts having IFN-γ-deficient CD8(+) T cells. Moreover, we observed that N. caninum-infected perforin-deficient mice presented parasitic burdens similar to those of infected wild-type controls. Altogether these results demonstrate that production of IFN-γ is a predominant protective mechanism conferred by CD8(+) T cells in the course of neosporosis.

  15. Genome-wide transcriptional profiling of Botrytis cinerea genes targeting plant cell walls during infections of different hosts

    PubMed Central

    Blanco-Ulate, Barbara; Morales-Cruz, Abraham; Amrine, Katherine C. H.; Labavitch, John M.; Powell, Ann L. T.; Cantu, Dario

    2014-01-01

    Cell walls are barriers that impair colonization of host tissues, but also are important reservoirs of energy-rich sugars. Growing hyphae of necrotrophic fungal pathogens, such as Botrytis cinerea (Botrytis, henceforth), secrete enzymes that disassemble cell wall polysaccharides. In this work we describe the annotation of 275 putative secreted Carbohydrate-Active enZymes (CAZymes) identified in the Botrytis B05.10 genome. Using RNAseq we determined which Botrytis CAZymes were expressed during infections of lettuce leaves, ripe tomato fruit, and grape berries. On the three hosts, Botrytis expressed a common group of 229 potentially secreted CAZymes, including 28 pectin backbone-modifying enzymes, 21 hemicellulose-modifying proteins, 18 enzymes that might target pectin and hemicellulose side-branches, and 16 enzymes predicted to degrade cellulose. The diversity of the Botrytis CAZymes may be partly responsible for its wide host range. Thirty-six candidate CAZymes with secretion signals were found exclusively when Botrytis interacted with ripe tomato fruit and grape berries. Pectin polysaccharides are notably abundant in grape and tomato cell walls, but lettuce leaf walls have less pectin and are richer in hemicelluloses and cellulose. The results of this study not only suggest that Botrytis targets similar wall polysaccharide networks on fruit and leaves, but also that it may selectively attack host wall polysaccharide substrates depending on the host tissue. PMID:25232357

  16. Host cell polarity proteins participate in innate immunity to Pseudomonas aeruginosa infection

    PubMed Central

    Tran, Cindy S.; Eran, Yoni; Ruch, Travis R.; Bryant, David M.; Datta, Anirban; Brakeman, Paul; Kierbel, Arlinet; Wittmann, Torsten; Metzger, Ross J.; Mostov, Keith E.; Engel, Joanne N.

    2014-01-01

    Summary The mucosal epithelium consists of polarized cells with distinct apical and basolateral membranes that serve as functional and physical barriers to the organisms’ exterior. The apical surface of the epithelium constitutes the first point of contact between mucosal pathogens, such as Pseudomonas aeruginosa, and their host. We observed that binding of P. aeruginosa aggregates to the apical surface of polarized cells leads to the striking formation of an actin-rich membrane protrusion with ‘inverted’ polarity, containing basolateral lipids and membrane components. Such protrusions were associated with a spatially localized host immune response to P. aeruginosa aggregates that required bacterial flagella and a Type III secretion system apparatus. Host protrusions form de novo underneath bacterial aggregates and involve the apical recruitment of a Par3/Par6α/aPKC/Rac1 signaling module for a robust, spatially localized host NFκB response. Our data reveal an unanticipated role for spatio-temporal epithelial polarity changes in the activation of innate immune responses. PMID:24832456

  17. Dendritic cells play a role in host susceptibility to Cryptosporidium parvum infection.

    PubMed

    Bedi, Brahmchetna; McNair, Nina N; Mead, Jan R

    2014-01-01

    Our previous studies have described dendritic cells (DCs) to be important sources of Th1 cytokines such as IL-12 and IL-2 in vitro, following stimulation with Cryptosporidium parvum antigens. We further established the role of DCs during cryptosporidiosis using a diphtheria toxin promoter regulated transgenic CD11c-DTR/EGFP mouse model. In vivo depletion of CD11c(+) cells in CD11c-DTR-Tg mice significantly increased susceptibility to C. parvum infection. Adoptive transfer of unstimulated or antigen stimulated DCs into CD11c(+) depleted CD11c-DTR-Tg mice resulted in an early decrease in parasite load at 4 days post infection. However, this response was transient since parasite load increased in mice engrafted with either unstimulated DCs or DCs stimulated with solubilized antigen by 6 days post infection. In contrast, in mice engrafted with DCs stimulated with live sporozoites, parasite load remained low during the entire period, suggesting the development of a more effective and sustained response. A corresponding increase in IFN-γ expression in T cells from spleen and mesenteric lymph nodes was also noted. Consistent with the in vivo engraftment study, DCs that are pulsed with live sporozoites in vitro and co-cultured with CD4(+) and CD8(+) T cells produced higher IFN-γ levels. Our study establishes the importance of DCs in susceptibility to infection by C. parvum and as important mediators of immune responses.

  18. Host Genetic Background Influences the Response to the Opportunistic Pseudomonas aeruginosa Infection Altering Cell-Mediated Immunity and Bacterial Replication

    PubMed Central

    Lorè, Nicola Ivan; Rossi, Giacomo; Cigana, Cristina; De Fino, Ida; Iraqi, Fuad A.; Bragonzi, Alessandra

    2014-01-01

    Pseudomonas aeruginosa is a common cause of healthcare-associated infections including pneumonia, bloodstream, urinary tract, and surgical site infections. The clinical outcome of P. aeruginosa infections may be extremely variable among individuals at risk and patients affected by cystic fibrosis. However, risk factors for P. aeruginosa infection remain largely unknown. To identify and track the host factors influencing P. aeruginosa lung infections, inbred immunocompetent mouse strains were screened in a pneumonia model system. A/J, BALB/cJ, BALB/cAnNCrl, BALB/cByJ, C3H/HeOuJ, C57BL/6J, C57BL/6NCrl, DBA/2J, and 129S2/SvPasCRL mice were infected with P. aeruginosa clinical strain and monitored for body weight and mortality up to seven days. The most deviant survival phenotypes were observed for A/J, 129S2/SvPasCRL and DBA/2J showing high susceptibility while BALB/cAnNCrl and C3H/HeOuJ showing more resistance to P. aeruginosa infection. Next, one of the most susceptible and resistant mouse strains were characterized for their deviant clinical and immunological phenotype by scoring bacterial count, cell-mediated immunity, cytokines and chemokines profile and lung pathology in an early time course. Susceptible A/J mice showed significantly higher bacterial burden, higher cytokines and chemokines levels but lower leukocyte recruitment, particularly neutrophils, when compared to C3H/HeOuJ resistant mice. Pathologic scores showed lower inflammatory severity, reduced intraluminal and interstitial inflammation extent, bronchial and parenchymal involvement and diminished alveolar damage in the lungs of A/J when compared to C3H/HeOuJ. Our findings indicate that during an early phase of infection a prompt inflammatory response in the airways set the conditions for a non-permissive environment to P. aeruginosa replication and lock the spread to other organs. Host gene(s) may have a role in the reduction of cell-mediated immunity playing a critical role in the control of P

  19. Host genetic background influences the response to the opportunistic Pseudomonas aeruginosa infection altering cell-mediated immunity and bacterial replication.

    PubMed

    De Simone, Maura; Spagnuolo, Lorenza; Lorè, Nicola Ivan; Rossi, Giacomo; Cigana, Cristina; De Fino, Ida; Iraqi, Fuad A; Bragonzi, Alessandra

    2014-01-01

    Pseudomonas aeruginosa is a common cause of healthcare-associated infections including pneumonia, bloodstream, urinary tract, and surgical site infections. The clinical outcome of P. aeruginosa infections may be extremely variable among individuals at risk and patients affected by cystic fibrosis. However, risk factors for P. aeruginosa infection remain largely unknown. To identify and track the host factors influencing P. aeruginosa lung infections, inbred immunocompetent mouse strains were screened in a pneumonia model system. A/J, BALB/cJ, BALB/cAnNCrl, BALB/cByJ, C3H/HeOuJ, C57BL/6J, C57BL/6NCrl, DBA/2J, and 129S2/SvPasCRL mice were infected with P. aeruginosa clinical strain and monitored for body weight and mortality up to seven days. The most deviant survival phenotypes were observed for A/J, 129S2/SvPasCRL and DBA/2J showing high susceptibility while BALB/cAnNCrl and C3H/HeOuJ showing more resistance to P. aeruginosa infection. Next, one of the most susceptible and resistant mouse strains were characterized for their deviant clinical and immunological phenotype by scoring bacterial count, cell-mediated immunity, cytokines and chemokines profile and lung pathology in an early time course. Susceptible A/J mice showed significantly higher bacterial burden, higher cytokines and chemokines levels but lower leukocyte recruitment, particularly neutrophils, when compared to C3H/HeOuJ resistant mice. Pathologic scores showed lower inflammatory severity, reduced intraluminal and interstitial inflammation extent, bronchial and parenchymal involvement and diminished alveolar damage in the lungs of A/J when compared to C3H/HeOuJ. Our findings indicate that during an early phase of infection a prompt inflammatory response in the airways set the conditions for a non-permissive environment to P. aeruginosa replication and lock the spread to other organs. Host gene(s) may have a role in the reduction of cell-mediated immunity playing a critical role in the control of P

  20. Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells.

    PubMed

    Flaherty, Rebecca A; Lee, Shaun W

    2016-08-19

    Many bacterial pathogens secrete potent toxins to aid in the destruction of host tissue, to initiate signaling changes in host cells or to manipulate immune system responses during the course of infection. Though methods have been developed to successfully purify and produce many of these important virulence factors, there are still many bacterial toxins whose unique structure or extensive post-translational modifications make them difficult to purify and study in in vitro systems. Furthermore, even when pure toxin can be obtained, there are many challenges associated with studying the specific effects of a toxin under relevant physiological conditions. Most in vitro cell culture models designed to assess the effects of secreted bacterial toxins on host cells involve incubating host cells with a one-time dose of toxin. Such methods poorly approximate what host cells actually experience during an infection, where toxin is continually produced by bacterial cells and allowed to accumulate gradually during the course of infection. This protocol describes the design of a permeable membrane insert-based bacterial infection system to study the effects of Streptolysin S, a potent toxin produced by Group A Streptococcus, on human epithelial keratinocytes. This system more closely mimics the natural physiological environment during an infection than methods where pure toxin or bacterial supernatants are directly applied to host cells. Importantly, this method also eliminates the bias of host responses that are due to direct contact between the bacteria and host cells. This system has been utilized to effectively assess the effects of Streptolysin S (SLS) on host membrane integrity, cellular viability, and cellular signaling responses. This technique can be readily applied to the study of other secreted virulence factors on a variety of mammalian host cell types to investigate the specific role of a secreted bacterial factor during the course of infection.

  1. Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells.

    PubMed

    Flaherty, Rebecca A; Lee, Shaun W

    2016-01-01

    Many bacterial pathogens secrete potent toxins to aid in the destruction of host tissue, to initiate signaling changes in host cells or to manipulate immune system responses during the course of infection. Though methods have been developed to successfully purify and produce many of these important virulence factors, there are still many bacterial toxins whose unique structure or extensive post-translational modifications make them difficult to purify and study in in vitro systems. Furthermore, even when pure toxin can be obtained, there are many challenges associated with studying the specific effects of a toxin under relevant physiological conditions. Most in vitro cell culture models designed to assess the effects of secreted bacterial toxins on host cells involve incubating host cells with a one-time dose of toxin. Such methods poorly approximate what host cells actually experience during an infection, where toxin is continually produced by bacterial cells and allowed to accumulate gradually during the course of infection. This protocol describes the design of a permeable membrane insert-based bacterial infection system to study the effects of Streptolysin S, a potent toxin produced by Group A Streptococcus, on human epithelial keratinocytes. This system more closely mimics the natural physiological environment during an infection than methods where pure toxin or bacterial supernatants are directly applied to host cells. Importantly, this method also eliminates the bias of host responses that are due to direct contact between the bacteria and host cells. This system has been utilized to effectively assess the effects of Streptolysin S (SLS) on host membrane integrity, cellular viability, and cellular signaling responses. This technique can be readily applied to the study of other secreted virulence factors on a variety of mammalian host cell types to investigate the specific role of a secreted bacterial factor during the course of infection. PMID:27585035

  2. Inhibition of host extracellular signal-regulated kinase (ERK) activation decreases new world alphavirus multiplication in infected cells

    SciTech Connect

    Voss, Kelsey; Amaya, Moushimi; Mueller, Claudius; Roberts, Brian; Kehn-Hall, Kylene; Bailey, Charles; Petricoin, Emanuel; Narayanan, Aarthi

    2014-11-15

    New World alphaviruses belonging to the family Togaviridae are classified as emerging infectious agents and Category B select agents. Our study is focused on the role of the host extracellular signal-regulated kinase (ERK) in the infectious process of New World alphaviruses. Infection of human cells by Venezuelan equine encephalitis virus (VEEV) results in the activation of the ERK-signaling cascade. Inhibition of ERK1/2 by the small molecule inhibitor Ag-126 results in inhibition of viral multiplication. Ag-126-mediated inhibition of VEEV was due to potential effects on early and late stages of the infectious process. While expression of viral proteins was down-regulated in Ag-126 treated cells, we did not observe any influence of Ag-126 on the nuclear distribution of capsid. Finally, Ag-126 exerted a broad-spectrum inhibitory effect on New World alphavirus multiplication, thus indicating that the host kinase, ERK, is a broad-spectrum candidate for development of novel therapeutics against New World alphaviruses. - Highlights: • VEEV infection activated multiple components of the ERK signaling cascade. • Inhibition of ERK activation using Ag-126 inhibited VEEV multiplication. • Activation of ERK by Ceramide C6 increased infectious titers of TC-83. • Ag-126 inhibited virulent strains of all New World alphaviruses. • Ag-126 treatment increased percent survival of infected cells.

  3. Ehrlichia chaffeensis infection in the reservoir host (white-tailed deer) and in an incidental host (dog) is impacted by its prior growth in macrophage and tick cell environments.

    PubMed

    Nair, Arathy D S; Cheng, Chuanmin; Jaworski, Deborah C; Willard, Lloyd H; Sanderson, Michael W; Ganta, Roman R

    2014-01-01

    Ehrlichia chaffeensis, transmitted from Amblyomma americanum ticks, causes human monocytic ehrlichiosis. It also infects white-tailed deer, dogs and several other vertebrates. Deer are its reservoir hosts, while humans and dogs are incidental hosts. E. chaffeensis protein expression is influenced by its growth in macrophages and tick cells. We report here infection progression in deer or dogs infected intravenously with macrophage- or tick cell-grown E. chaffeensis or by tick transmission in deer. Deer and dogs developed mild fever and persistent rickettsemia; the infection was detected more frequently in the blood of infected animals with macrophage inoculum compared to tick cell inoculum or tick transmission. Tick cell inoculum and tick transmission caused a drop in tick infection acquisition rates compared to infection rates in ticks fed on deer receiving macrophage inoculum. Independent of deer or dogs, IgG antibody response was higher in animals receiving macrophage inoculum against macrophage-derived Ehrlichia antigens, while it was significantly lower in the same animals against tick cell-derived Ehrlichia antigens. Deer infected with tick cell inoculum and tick transmission caused a higher antibody response to tick cell cultured bacterial antigens compared to the antibody response for macrophage cultured antigens for the same animals. The data demonstrate that the host cell-specific E. chaffeensis protein expression influences rickettsemia in a host and its acquisition by ticks. The data also reveal that tick cell-derived inoculum is similar to tick transmission with reduced rickettsemia, IgG response and tick acquisition of E. chaffeensis.

  4. Transfer of immunity against lethal murine Francisella infection by specific antibody depends on host gamma interferon and T cells.

    PubMed Central

    Rhinehart-Jones, T R; Fortier, A H; Elkins, K L

    1994-01-01

    Both serum and spleen cells from mice immune to Francisella tularensis transfer protection to naive recipients. Here we characterize the mechanism of protection induced by transfer of immune mouse serum (IMS). IMS obtained 4 weeks after intradermal infection with 10(3) bacteria of the live vaccine strain (LVS) contained high levels of immunoglobulin G2 (IgG2a) and IgM (end point titers, 1:16,600 and 1:7,200, respectively) and little IgG1, IgG2b, or IgG3. LVS-specific antibodies were detected 5 days after intradermal infection, and reached peak levels by 2 weeks postinfection. Only sera obtained 10 days or more after sublethal infection, when IgG titers peaked, transferred protection against a challenge of 100 50% lethal doses (LD50s). Purified high-titer IgG anti-LVS antibody but not IgM anti-LVS antibody was responsible for transfer of protection against an intraperitoneal challenge of up to 3,000 LD50s. IMS had no direct toxic effects on LVS and did not affect uptake or growth of bacteria in association with peritoneal cells. One day after LVS infection, liver, spleen, and lung tissue from mice treated with IMS contained 1 to 2 log units fewer bacteria than did tissue from mice treated with normal mouse serum or phosphate-buffered saline. Between 2 and 4 days after infection, however, bacterial growth rates in tissues were similar in both serum-protected mice and unprotected mice. Bacterial burdens in IMS-treated, LVS-infected mice declined in infected tissues after day 5, whereas control animals died. This lag phase suggested that development of a host response was involved in complete bacterial clearance. In fact, transfer of IMS into normal recipients that were simultaneously treated with anti-gamma interferon and challenged with LVS did not protect mice from death. Further, transfer of IMS into athymic nu/nu mice did not protect against LVS challenge; protection was, however, reconstituted by transfer of normal T cells into nu/nu mice. Thus, "passive

  5. Villosiclava virens infects specifically rice and barley stamen filaments due to the unique host cell walls.

    PubMed

    Yong, Ming-Li; Fan, Lin-Lin; Li, Dan-Yang; Liu, Yi-Jia; Cheng, Fang-Min; Xu, Ying; Wang, Zheng-Yi; Hu, Dong-Wei

    2016-09-01

    Rice false smut, caused by the fungal pathogen Villosiclava virens, is one of the most important rice diseases in the world. Previous studies reported that the pathogen has less number of cell wall-degraded genes and attacks dominantly rice stamen filaments and extends intercellularly. To reveal why the fungus infects plant stamen filaments, inoculation test on barley was carried out with the similar protocol to rice. The experimental results showed that the fungus could penetrate quickly into barley stamen filaments and extends both intracellularly and intercellularly, usually resulting in severe damage of the stamen filament tissues. It also attacked young barley lodicules and grew intercellularly by chance. The light microscopic observations found that the epidermal and cortex cells in barley stamen filaments arranged loosely with very thick cell walls and large cell gaps. Cellulose microfibrils in barley stamen filament cell walls arranged very sparsely so that the cell walls looked like transparent. The cell walls were very soft and flexible, and often folded. However, V. virens extended dominantly in the noncellulose regions and seemed never to degrade microfibrils in barley and rice cell walls. This suggested that the unique structures of rice and barley stamen filaments should be fit for their function of elongation in anthesis, and also endow with the susceptibility to the fungus, V. virens. PMID:27357263

  6. Villosiclava virens infects specifically rice and barley stamen filaments due to the unique host cell walls.

    PubMed

    Yong, Ming-Li; Fan, Lin-Lin; Li, Dan-Yang; Liu, Yi-Jia; Cheng, Fang-Min; Xu, Ying; Wang, Zheng-Yi; Hu, Dong-Wei

    2016-09-01

    Rice false smut, caused by the fungal pathogen Villosiclava virens, is one of the most important rice diseases in the world. Previous studies reported that the pathogen has less number of cell wall-degraded genes and attacks dominantly rice stamen filaments and extends intercellularly. To reveal why the fungus infects plant stamen filaments, inoculation test on barley was carried out with the similar protocol to rice. The experimental results showed that the fungus could penetrate quickly into barley stamen filaments and extends both intracellularly and intercellularly, usually resulting in severe damage of the stamen filament tissues. It also attacked young barley lodicules and grew intercellularly by chance. The light microscopic observations found that the epidermal and cortex cells in barley stamen filaments arranged loosely with very thick cell walls and large cell gaps. Cellulose microfibrils in barley stamen filament cell walls arranged very sparsely so that the cell walls looked like transparent. The cell walls were very soft and flexible, and often folded. However, V. virens extended dominantly in the noncellulose regions and seemed never to degrade microfibrils in barley and rice cell walls. This suggested that the unique structures of rice and barley stamen filaments should be fit for their function of elongation in anthesis, and also endow with the susceptibility to the fungus, V. virens.

  7. NADPH Oxidase 1 Is Associated with Altered Host Survival and T Cell Phenotypes after Influenza A Virus Infection in Mice.

    PubMed

    Hofstetter, Amelia R; De La Cruz, Juan A; Cao, Weiping; Patel, Jenish; Belser, Jessica A; McCoy, James; Liepkalns, Justine S; Amoah, Samuel; Cheng, Guangjie; Ranjan, Priya; Diebold, Becky A; Shieh, Wun-Ju; Zaki, Sherif; Katz, Jacqueline M; Sambhara, Suryaprakash; Lambeth, J David; Gangappa, Shivaprakash

    2016-01-01

    The role of the reactive oxygen species-producing NADPH oxidase family of enzymes in the pathology of influenza A virus infection remains enigmatic. Previous reports implicated NADPH oxidase 2 in influenza A virus-induced inflammation. In contrast, NADPH oxidase 1 (Nox1) was reported to decrease inflammation in mice within 7 days post-influenza A virus infection. However, the effect of NADPH oxidase 1 on lethality and adaptive immunity after influenza A virus challenge has not been explored. Here we report improved survival and decreased morbidity in mice with catalytically inactive NADPH oxidase 1 (Nox1*/Y) compared with controls after challenge with A/PR/8/34 influenza A virus. While changes in lung inflammation were not obvious between Nox1*/Y and control mice, we observed alterations in the T cell response to influenza A virus by day 15 post-infection, including increased interleukin-7 receptor-expressing virus-specific CD8+ T cells in lungs and draining lymph nodes of Nox1*/Y, and increased cytokine-producing T cells in lungs and spleen. Furthermore, a greater percentage of conventional and interstitial dendritic cells from Nox1*/Y draining lymph nodes expressed the co-stimulatory ligand CD40 within 6 days post-infection. Results indicate that NADPH oxidase 1 modulates the innate and adaptive cellular immune response to influenza virus infection, while also playing a role in host survival. Results suggest that NADPH oxidase 1 inhibitors may be beneficial as adjunct therapeutics during acute influenza infection.

  8. NADPH Oxidase 1 Is Associated with Altered Host Survival and T Cell Phenotypes after Influenza A Virus Infection in Mice

    PubMed Central

    Hofstetter, Amelia R.; De La Cruz, Juan A.; Cao, Weiping; Patel, Jenish; Belser, Jessica A.; McCoy, James; Liepkalns, Justine S.; Amoah, Samuel; Cheng, Guangjie; Ranjan, Priya; Diebold, Becky A.; Shieh, Wun-Ju; Zaki, Sherif; Katz, Jacqueline M.; Sambhara, Suryaprakash; Lambeth, J. David; Gangappa, Shivaprakash

    2016-01-01

    The role of the reactive oxygen species-producing NADPH oxidase family of enzymes in the pathology of influenza A virus infection remains enigmatic. Previous reports implicated NADPH oxidase 2 in influenza A virus-induced inflammation. In contrast, NADPH oxidase 1 (Nox1) was reported to decrease inflammation in mice within 7 days post-influenza A virus infection. However, the effect of NADPH oxidase 1 on lethality and adaptive immunity after influenza A virus challenge has not been explored. Here we report improved survival and decreased morbidity in mice with catalytically inactive NADPH oxidase 1 (Nox1*/Y) compared with controls after challenge with A/PR/8/34 influenza A virus. While changes in lung inflammation were not obvious between Nox1*/Y and control mice, we observed alterations in the T cell response to influenza A virus by day 15 post-infection, including increased interleukin-7 receptor-expressing virus-specific CD8+ T cells in lungs and draining lymph nodes of Nox1*/Y, and increased cytokine-producing T cells in lungs and spleen. Furthermore, a greater percentage of conventional and interstitial dendritic cells from Nox1*/Y draining lymph nodes expressed the co-stimulatory ligand CD40 within 6 days post-infection. Results indicate that NADPH oxidase 1 modulates the innate and adaptive cellular immune response to influenza virus infection, while also playing a role in host survival. Results suggest that NADPH oxidase 1 inhibitors may be beneficial as adjunct therapeutics during acute influenza infection. PMID:26910342

  9. The murine coronavirus mouse hepatitis virus strain A59 from persistently infected murine cells exhibits an extended host range.

    PubMed Central

    Schickli, J H; Zelus, B D; Wentworth, D E; Sawicki, S G; Holmes, K V

    1997-01-01

    In murine 17 Cl 1 cells persistently infected with murine coronavirus mouse hepatitis virus strain A59 (MHV-A59), expression of the virus receptor glycoprotein MHVR was markedly reduced (S. G. Sawicki, J. H. Lu, and K. V. Holmes, J. Virol. 69:5535-5543, 1995). Virus isolated from passage 600 of the persistently infected cells made smaller plaques on 17 Cl 1 cells than did MHV-A59. Unlike the parental MHV-A59, this variant virus also infected the BHK-21 (BHK) line of hamster cells. Virus plaque purified on BHK cells (MHV/BHK) grew more slowly in murine cells than did MHV-A59, and the rate of viral RNA synthesis was lower and the development of the viral nucleocapsid (N) protein was slower than those of MHV-A59. MHV/BHK was 100-fold more resistant to neutralization with the purified soluble recombinant MHV receptor glycoprotein (sMHVR) than was MHV-A59. Pretreatment of 17 Cl 1 cells with anti-MHVR monoclonal antibody CC1 protected the cells from infection with MHV-A59 but only partially protected them from infection with MHV/BHK. Thus, although MHV/BHK could still utilize MHVR as a receptor, its interactions with the receptor were significantly different from those of MHV-A59. To determine whether a hemagglutinin esterase (HE) glycoprotein that could bind the virions to 9-O-acetylated neuraminic acid moieties on the cell surface was expressed by MHV/BHK, an in situ esterase assay was used. No expression of HE activity was detected in 17 Cl 1 cells infected with MHV/BHK, suggesting that this virus, like MHV-A59, bound to cell membranes via its S glycoprotein. MHV/BHK was able to infect cell lines from many mammalian species, including murine (17 Cl 1), hamster (BHK), feline (Fcwf), bovine (MDBK), rat (RIE), monkey (Vero), and human (L132 and HeLa) cell lines. MHV/BHK could not infect dog kidney (MDCK I) or swine testis (ST) cell lines. Thus, in persistently infected murine cell lines that express very low levels of virus receptor MHVR and which also have and may

  10. Host-Pathogen Interactions in Campylobacter Infections: the Host Perspective

    PubMed Central

    Janssen, Riny; Krogfelt, Karen A.; Cawthraw, Shaun A.; van Pelt, Wilfrid; Wagenaar, Jaap A.; Owen, Robert J.

    2008-01-01

    Campylobacter is a major cause of acute bacterial diarrhea in humans worldwide. This study was aimed at summarizing the current understanding of host mechanisms involved in the defense against Campylobacter by evaluating data available from three sources: (i) epidemiological observations, (ii) observations of patients, and (iii) experimental observations including observations of animal models and human volunteer studies. Analysis of available data clearly indicates that an effective immune system is crucial for the host defense against Campylobacter infection. Innate, cell-mediated, and humoral immune responses are induced during Campylobacter infection, but the relative importance of these mechanisms in conferring protective immunity against reinfection is unclear. Frequent exposure to Campylobacter does lead to the induction of short-term protection against disease but most probably not against colonization. Recent progress in the development of more suitable animal models for studying Campylobacter infection has opened up possibilities to study the importance of innate and adaptive immunity during infection and in protection against reinfection. In addition, advances in genomics and proteomics technologies will enable more detailed molecular studies. Such studies combined with better integration of host and pathogen research driven by epidemiological findings may truly advance our understanding of Campylobacter infection in humans. PMID:18625685

  11. Stable Phenotypic Changes of the Host T Cells Are Essential to the Long-Term Stability of Latent HIV-1 Infection

    PubMed Central

    Seu, Lillian; Sabbaj, Steffanie; Duverger, Alexandra; Wagner, Frederic; Anderson, Joshua C.; Davies, Elizabeth; Wolschendorf, Frank; Willey, Christopher D.; Saag, Michael S.; Goepfert, Paul

    2015-01-01

    ABSTRACT The extreme stability of the latent HIV-1 reservoir in the CD4+ memory T cell population prevents viral eradication with current antiretroviral therapy. It has been demonstrated that homeostatic T cell proliferation and clonal expansion of latently infected T cells due to viral integration into specific genes contribute to this extraordinary reservoir stability. Nevertheless, given the constant exposure of the memory T cell population to specific antigen or bystander activation, this reservoir stability seems remarkable, unless it is assumed that latent HIV-1 resides exclusively in memory T cells that recognize rare antigens. Another explanation for the stability of the reservoir could be that the latent HIV-1 reservoir is associated with an unresponsive T cell phenotype. We demonstrate here that host cells of latent HIV-1 infection events were functionally altered in ways that are consistent with the idea of an anergic, unresponsive T cell phenotype. Manipulations that induced or mimicked an anergic T cell state promoted latent HIV-1 infection. Kinome analysis data reflected this altered host cell phenotype at a system-wide level and revealed how the stable kinase activity changes networked to stabilize latent HIV-1 infection. Protein-protein interaction networks generated from kinome data could further be used to guide targeted genetic or pharmacological manipulations that alter the stability of latent HIV-1 infection. In summary, our data demonstrate that stable changes to the signal transduction and transcription factor network of latently HIV-1 infected host cells are essential to the ability of HIV-1 to establish and maintain latent HIV-1 infection status. IMPORTANCE The extreme stability of the latent HIV-1 reservoir allows the infection to persist for the lifetime of a patient, despite completely suppressive antiretroviral therapy. This extreme reservoir stability is somewhat surprising, since the latently HIV-1 infected CD4+ memory T cells that

  12. Comparative Proteomics Reveals Important Viral-Host Interactions in HCV-Infected Human Liver Cells.

    PubMed

    Liu, Shufeng; Zhao, Ting; Song, BenBen; Zhou, Jianhua; Wang, Tony T

    2016-01-01

    Hepatitis C virus (HCV) poses a global threat to public health. HCV envelop protein E2 is the major component on the virus envelope, which plays an important role in virus entry and morphogenesis. Here, for the first time, we affinity purified E2 complex formed in HCV-infected human hepatoma cells and conducted comparative mass spectrometric analyses. 85 cellular proteins and three viral proteins were successfully identified in three independent trials, among which alphafetoprotein (AFP), UDP-glucose: glycoprotein glucosyltransferase 1 (UGT1) and HCV NS4B were further validated as novel E2 binding partners. Subsequent functional characterization demonstrated that gene silencing of UGT1 in human hepatoma cell line Huh7.5.1 markedly decreased the production of infectious HCV, indicating a regulatory role of UGT1 in viral lifecycle. Domain mapping experiments showed that HCV E2-NS4B interaction requires the transmembrane domains of the two proteins. Altogether, our proteomics study has uncovered key viral and cellular factors that interact with E2 and provided new insights into our understanding of HCV infection. PMID:26808496

  13. Comparative Proteomics Reveals Important Viral-Host Interactions in HCV-Infected Human Liver Cells

    PubMed Central

    Song, BenBen; Zhou, Jianhua; Wang, Tony T.

    2016-01-01

    Hepatitis C virus (HCV) poses a global threat to public health. HCV envelop protein E2 is the major component on the virus envelope, which plays an important role in virus entry and morphogenesis. Here, for the first time, we affinity purified E2 complex formed in HCV-infected human hepatoma cells and conducted comparative mass spectrometric analyses. 85 cellular proteins and three viral proteins were successfully identified in three independent trials, among which alphafetoprotein (AFP), UDP-glucose: glycoprotein glucosyltransferase 1 (UGT1) and HCV NS4B were further validated as novel E2 binding partners. Subsequent functional characterization demonstrated that gene silencing of UGT1 in human hepatoma cell line Huh7.5.1 markedly decreased the production of infectious HCV, indicating a regulatory role of UGT1 in viral lifecycle. Domain mapping experiments showed that HCV E2-NS4B interaction requires the transmembrane domains of the two proteins. Altogether, our proteomics study has uncovered key viral and cellular factors that interact with E2 and provided new insights into our understanding of HCV infection. PMID:26808496

  14. Transmitted Virus Fitness and Host T Cell Responses Collectively Define Divergent Infection Outcomes in Two HIV-1 Recipients

    PubMed Central

    Yue, Ling; Pfafferott, Katja J.; Baalwa, Joshua; Conrod, Karen; Dong, Catherine C.; Chui, Cecilia; Rong, Rong; Claiborne, Daniel T.; Prince, Jessica L.; Tang, Jianming; Ribeiro, Ruy M.; Cormier, Emmanuel; Hahn, Beatrice H.; Perelson, Alan S.; Shaw, George M.; Karita, Etienne; Gilmour, Jill; Goepfert, Paul; Derdeyn, Cynthia A.; Allen, Susan A.; Borrow, Persephone; Hunter, Eric

    2015-01-01

    Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/founder (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of T cell

  15. Transmitted virus fitness and host T cell responses collectively define divergent infection outcomes in two HIV-1 recipients

    DOE PAGESBeta

    Yue, Ling; Pfafferott, Katja J.; Baalwa, Joshua; Conrod, Karen; Dong, Catherine C.; Chui, Cecilia; Rong, Rong; Claiborne, Daniel T.; Prince, Jessica L.; Tang, Jianming; et al

    2015-01-08

    Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/foundermore » (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of

  16. Transmitted virus fitness and host T cell responses collectively define divergent infection outcomes in two HIV-1 recipients

    SciTech Connect

    Yue, Ling; Pfafferott, Katja J.; Baalwa, Joshua; Conrod, Karen; Dong, Catherine C.; Chui, Cecilia; Rong, Rong; Claiborne, Daniel T.; Prince, Jessica L.; Tang, Jianming; Ribeiro, Ruy M.; Cormier, Emmanuel; Hahn, Beatrice H.; Perelson, Alan S.; Shaw, George M.; Karita, Etienne; Gilmour, Jill; Goepfert, Paul; Derdeyn, Cynthia A.; Allen, Susan A.; Borrow, Persephone; Hunter, Eric; Douek, Daniel C.

    2015-01-08

    Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/founder (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro, while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a

  17. FdhTU-Modulated Formate Dehydrogenase Expression and Electron Donor Availability Enhance Recovery of Campylobacter jejuni following Host Cell Infection

    PubMed Central

    Pryjma, Mark; Apel, Dmitry; Huynh, Steven; Parker, Craig T.

    2012-01-01

    Campylobacter jejuni is a food-borne bacterial pathogen that colonizes the intestinal tract and causes severe gastroenteritis. Interaction with host epithelial cells is thought to enhance severity of disease, and the ability of C. jejuni to modulate its metabolism in different in vivo and environmental niches contributes to its success as a pathogen. A C. jejuni operon comprising two genes that we designated fdhT (CJJ81176_1492) and fdhU (CJJ81176_1493) is conserved in many bacterial species. Deletion of fdhT or fdhU in C. jejuni resulted in apparent defects in adherence and/or invasion of Caco-2 epithelial cells when assessed by CFU enumeration on standard Mueller-Hinton agar. However, fluorescence microscopy indicated that each mutant invaded cells at wild-type levels, instead suggesting roles for FdhTU in either intracellular survival or postinvasion recovery. The loss of fdhU caused reduced mRNA levels of formate dehydrogenase (FDH) genes and a severe defect in FDH activity. Cell infection phenotypes of a mutant deleted for the FdhA subunit of FDH and an ΔfdhU ΔfdhA double mutant were similar to those of a ΔfdhU mutant, which likewise suggested that FdhU and FdhA function in the same pathway. Cell infection assays followed by CFU enumeration on plates supplemented with sodium sulfite abolished the ΔfdhU and ΔfdhA mutant defects and resulted in significantly enhanced recovery of all strains, including wild type, at the invasion and intracellular survival time points. Collectively, our data indicate that FdhTU and FDH are required for optimal recovery following cell infection and suggest that C. jejuni alters its metabolic potential in the intracellular environment. PMID:22636777

  18. Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis.

    PubMed

    Kodama, Y; Fujishima, M

    2015-12-30

    Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria.

  19. Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis.

    PubMed

    Kodama, Y; Fujishima, M

    2015-01-01

    Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria. PMID:26718931

  20. Differences in infectivity between endosymbiotic Chlorella variabilis cultivated outside host Paramecium bursaria for 50 years and those immediately isolated from host cells after one year of reendosymbiosis

    PubMed Central

    Kodama, Y.; Fujishima, M.

    2016-01-01

    ABSTRACT Chlorella variabilis strain NC64A is an intracellular photobiont of the ciliate Paramecium bursaria. NC64A was isolated from P. bursaria nearly 50 years ago and was thereafter cultivated outside the host. This study was undertaken to detect changes in its infectivity to P. bursaria and its auxotrophy for growth outside the host induced during long-term cultivation. NC64A can grow in Modified Bold's Basal Medium but not in C medium, whereas another symbiotic Chlorella variabilis strain, 1N, that was recently isolated from the host grew in C medium but not in Modified Bold's Basal Medium. With regards infectivity, NC64A in the logarithmic phase of growth showed low infectivity to alga-removed P. bursaria cells, whereas those in the early stationary phase showed high infectivity of about 30%. Those in the decay phase of growth showed no infectivity. Results show that NC64A has infectivity, but the infection rate depends on their culture age in the growth curve. Furthermore, NC64A that had been re-infected to P. bursaria for more than one year and isolated from the host showed a nearly 100% infection rate, which indicates that NC64A can recover its infectivity by re-infection to P. bursaria. PMID:26718931

  1. Utilization of human DC-SIGN and L-SIGN for entry and infection of host cells by the New World arenavirus, Junín virus

    PubMed Central

    Belouzard, Sandrine; Cordo, Sandra M.; Candurra, Nélida A.; Whittaker, Gary R.

    2014-01-01

    The target cell tropism of enveloped viruses is regulated by interactions between viral proteins and cellular receptors determining susceptibility at a host cell, tissue or species level. However, a number of additional cell-surface moieties can also bind viral envelope glycoproteins and could act as capture receptors, serving as attachment factors to concentrate virus particles on the cell surface, or to disseminate the virus infection to target organs or susceptible cells within the host. Here, we used Junín virus (JUNV) or JUNV glycoprotein complex (GPC)-pseudotyped particles to study their ability to be internalized by the human C-type lectins hDC- or hL-SIGN. Our results provide evidence that hDC- and hL-SIGN can mediate the entry of Junín virus into cells, and may play an important role in virus infection and dissemination in the host. PMID:24183720

  2. Disseminated Cryptococcal infection in an immunocompetent host mimicking plasma cell disorder: a case report and literature review

    PubMed Central

    Abid, Muhammad Bilal; De Mel, Sanjay; Limei, Michelle Poon

    2015-01-01

    Key Clinical Message Cryptococcosis is a potentially fatal fungal infection caused mainly by Cryptocococcus neoformans (CN) species and it rarely infects immunocompetent hosts. The outcomes are better only if the condition is suspected and diagnosed early and treatment is instituted. PMID:25984313

  3. Ehrlichia chaffeensis infection in the reservoir host (white-tailed deer) and in an incidental host (dog) is impacted by its prior growth in macrophage and tick cell environments.

    PubMed

    Nair, Arathy D S; Cheng, Chuanmin; Jaworski, Deborah C; Willard, Lloyd H; Sanderson, Michael W; Ganta, Roman R

    2014-01-01

    Ehrlichia chaffeensis, transmitted from Amblyomma americanum ticks, causes human monocytic ehrlichiosis. It also infects white-tailed deer, dogs and several other vertebrates. Deer are its reservoir hosts, while humans and dogs are incidental hosts. E. chaffeensis protein expression is influenced by its growth in macrophages and tick cells. We report here infection progression in deer or dogs infected intravenously with macrophage- or tick cell-grown E. chaffeensis or by tick transmission in deer. Deer and dogs developed mild fever and persistent rickettsemia; the infection was detected more frequently in the blood of infected animals with macrophage inoculum compared to tick cell inoculum or tick transmission. Tick cell inoculum and tick transmission caused a drop in tick infection acquisition rates compared to infection rates in ticks fed on deer receiving macrophage inoculum. Independent of deer or dogs, IgG antibody response was higher in animals receiving macrophage inoculum against macrophage-derived Ehrlichia antigens, while it was significantly lower in the same animals against tick cell-derived Ehrlichia antigens. Deer infected with tick cell inoculum and tick transmission caused a higher antibody response to tick cell cultured bacterial antigens compared to the antibody response for macrophage cultured antigens for the same animals. The data demonstrate that the host cell-specific E. chaffeensis protein expression influences rickettsemia in a host and its acquisition by ticks. The data also reveal that tick cell-derived inoculum is similar to tick transmission with reduced rickettsemia, IgG response and tick acquisition of E. chaffeensis. PMID:25303515

  4. Temporal Transcriptional Response during Infection of Type II Alveolar Epithelial Cells with Francisella tularensis Live Vaccine Strain (LVS) Supports a General Host Suppression and Bacterial Uptake by Macropinocytosis*

    PubMed Central

    Bradburne, Christopher E.; Verhoeven, Anne B.; Manyam, Ganiraju C.; Chaudhry, Saira A.; Chang, Eddie L.; Thach, Dzung C.; Bailey, Charles L.; van Hoek, Monique L.

    2013-01-01

    Pneumonic tularemia is caused by inhalation of Francisella tularensis, one of the most infectious microbes known. We wanted to study the kinetics of the initial and early interactions between bacterium and host cells in the lung. To do this, we examined the infection of A549 airway epithelial cells with the live vaccine strain (LVS) of F. tularensis. A549 cells were infected and analyzed for global transcriptional response at multiple time points up to 16 h following infection. At 15 min and 2 h, a strong transcriptional response was observed including cytoskeletal rearrangement, intracellular transport, and interferon signaling. However, at later time points (6 and 16 h), very little differential gene expression was observed, indicating a general suppression of the host response consistent with other reported cell lines and murine tissues. Genes for macropinocytosis and actin/cytoskeleton rearrangement were highly up-regulated and common to the 15 min and 2 h time points, suggesting the use of this method for bacterial entry into cells. We demonstrate macropinocytosis through the uptake of FITC-dextran and amiloride inhibition of Francisella LVS uptake. Our results suggest that macropinocytosis is a potential mechanism of intracellular entry by LVS and that the host cell response is suppressed during the first 2–6 h of infection. These results suggest that the attenuated Francisella LVS induces significant host cell signaling at very early time points after the bacteria's interaction with the cell. PMID:23322778

  5. Infection of human urethral epithelium with Neisseria gonorrhoeae elicits an upregulation of host anti-apoptotic factors and protects cells from staurosporine-induced apoptosis.

    PubMed

    Binnicker, Matthew J; Williams, Richard D; Apicella, Michael A

    2003-08-01

    In order to better understand the host response to an infection with Neisseria gonorrhoeae, microarray technology was used to analyse the gene expression profile between uninfected and infected human urethral epithelium. The anti-apoptotic genes bfl-1, cox-2 and c-IAP-2 were identified to be upregulated approximately eight-, four- or twofold, respectively, following infection. Subsequent assays including RT-PCR, real time RT-PCR and RNase protection confirmed the increased expression of these apoptotic regulators, and identified that a fourth anti-apoptotic factor, mcl-1, is also upregulated. RT-PCR and RNase protection also showed that key pro-apoptotic factors including bax, bad and bak do not change in expression. Furthermore, our studies demonstrated that infection with the gonococcus partially protects urethral epithelium from apoptosis induced by the protein kinase inhibitor, staurosporine (STS). This work shows that following infection with Neisseria gonorrhoeae, several host anti-apoptotic factors are upregulated. In addition, a gonococcal infection protects host cells from subsequent STS-induced death. The regulation of host cell death by the gonococcus may represent a mechanism employed by this pathogen to survive and proliferate in host epithelium. PMID:12864814

  6. Host AMPK Is a Modulator of Plasmodium Liver Infection.

    PubMed

    Ruivo, Margarida T Grilo; Vera, Iset Medina; Sales-Dias, Joana; Meireles, Patrícia; Gural, Nil; Bhatia, Sangeeta N; Mota, Maria M; Mancio-Silva, Liliana

    2016-09-01

    Manipulation of the master regulator of energy homeostasis AMP-activated protein kinase (AMPK) activity is a strategy used by many intracellular pathogens for successful replication. Infection by most pathogens leads to an activation of host AMPK activity due to the energetic demands placed on the infected cell. Here, we demonstrate that the opposite is observed in cells infected with rodent malaria parasites. Indeed, AMPK activity upon the infection of hepatic cells is suppressed and dispensable for successful infection. By contrast, an overactive AMPK is deleterious to intracellular growth and replication of different Plasmodium spp., including the human malaria parasite, P. falciparum. The negative impact of host AMPK activity on infection was further confirmed in mice under conditions that activate its function. Overall, this work establishes the role of host AMPK signaling as a suppressive pathway of Plasmodium hepatic infection and as a potential target for host-based antimalarial interventions. PMID:27568570

  7. Mapping epigenetic changes to the host cell genome induced by Burkholderia pseudomallei reveals pathogen-specific and pathogen-generic signatures of infection

    PubMed Central

    Cizmeci, Deniz; Dempster, Emma L.; Champion, Olivia L.; Wagley, Sariqa; Akman, Ozgur E.; Prior, Joann L.; Soyer, Orkun S.; Mill, Jonathan; Titball, Richard W.

    2016-01-01

    The potential for epigenetic changes in host cells following microbial infection has been widely suggested, but few examples have been reported. We assessed genome-wide patterns of DNA methylation in human macrophage-like U937 cells following infection with Burkholderia pseudomallei, an intracellular bacterial pathogen and the causative agent of human melioidosis. Our analyses revealed significant changes in host cell DNA methylation, at multiple CpG sites in the host cell genome, following infection. Infection induced differentially methylated probes (iDMPs) showing the greatest changes in DNA methylation were found to be in the vicinity of genes involved in inflammatory responses, intracellular signalling, apoptosis and pathogen-induced signalling. A comparison of our data with reported methylome changes in cells infected with M. tuberculosis revealed commonality of differentially methylated genes, including genes involved in T cell responses (BCL11B, FOXO1, KIF13B, PAWR, SOX4, SYK), actin cytoskeleton organisation (ACTR3, CDC42BPA, DTNBP1, FERMT2, PRKCZ, RAC1), and cytokine production (FOXP1, IRF8, MR1). Overall our findings show that pathogenic-specific and pathogen-common changes in the methylome occur following infection. PMID:27484700

  8. The influenza fingerprints: NS1 and M1 proteins contribute to specific host cell ultrastructure signatures upon infection by different influenza A viruses

    SciTech Connect

    Terrier, Olivier; Moules, Vincent; Carron, Coralie; Cartet, Gaeelle; Frobert, Emilie; Yver, Matthieu; Traversier, Aurelien; Wolff, Thorsten; Naffakh, Nadia; and others

    2012-10-10

    Influenza A are nuclear replicating viruses which hijack host machineries in order to achieve optimal infection. Numerous functional virus-host interactions have now been characterized, but little information has been gathered concerning their link to the virally induced remodeling of the host cellular architecture. In this study, we infected cells with several human and avian influenza viruses and we have analyzed their ultrastructural modifications by using electron and confocal microscopy. We discovered that infections lead to a major and systematic disruption of nucleoli and the formation of a large number of diverse viral structures showing specificity that depended on the subtype origin and genomic composition of viruses. We identified NS1 and M1 proteins as the main actors in the remodeling of the host ultra-structure and our results suggest that each influenza A virus strain could be associated with a specific cellular fingerprint, possibly correlated to the functional properties of their viral components.

  9. Secretion of Antonospora (Paranosema) locustae proteins into infected cells suggests an active role of microsporidia in the control of host programs and metabolic processes.

    PubMed

    Senderskiy, Igor V; Timofeev, Sergey A; Seliverstova, Elena V; Pavlova, Olga A; Dolgikh, Viacheslav V

    2014-01-01

    Molecular tools of the intracellular protozoan pathogens Apicomplexa and Kinetoplastida for manipulation of host cell machinery have been the focus of investigation for approximately two decades. Microsporidia, fungi-related microorganisms forming another large group of obligate intracellular parasites, are characterized by development in direct contact with host cytoplasm (the majority of species), strong minimization of cell machinery, and acquisition of unique transporters to exploit host metabolic system. All the aforementioned features are suggestive of the ability of microsporidia to modify host metabolic and regulatory pathways. Seven proteins of the microsporidium Antonospora (Paranosema) locustae with predicted signal peptides but without transmembrane domains were overexpressed in Escherichia coli. Western-blot analysis with antibodies against recombinant products showed secretion of parasite proteins from different functional categories into the infected host cell. Secretion of parasite hexokinase and α/β-hydrolase was confirmed by immunofluorescence microscopy. In addition, this method showed specific accumulation of A. locustae hexokinase in host nuclei. Expression of hexokinase, trehalase, and two leucine-rich repeat proteins without any exogenous signal peptide led to their secretion in the yeast Pichia pastoris. In contrast, α/β-hydrolase was not found in the culture medium, though a significant amount of this enzyme accumulated in the yeast membrane fraction. These results suggest that microsporidia possess a broad set of enzymes and regulatory proteins secreted into infected cells to control host metabolic processes and molecular programs. PMID:24705470

  10. Secretion of Antonospora (Paranosema) locustae Proteins into Infected Cells Suggests an Active Role of Microsporidia in the Control of Host Programs and Metabolic Processes

    PubMed Central

    Senderskiy, Igor V.; Timofeev, Sergey A.; Seliverstova, Elena V.; Pavlova, Olga A.; Dolgikh, Viacheslav V.

    2014-01-01

    Molecular tools of the intracellular protozoan pathogens Apicomplexa and Kinetoplastida for manipulation of host cell machinery have been the focus of investigation for approximately two decades. Microsporidia, fungi-related microorganisms forming another large group of obligate intracellular parasites, are characterized by development in direct contact with host cytoplasm (the majority of species), strong minimization of cell machinery, and acquisition of unique transporters to exploit host metabolic system. All the aforementioned features are suggestive of the ability of microsporidia to modify host metabolic and regulatory pathways. Seven proteins of the microsporidium Antonospora (Paranosema) locustae with predicted signal peptides but without transmembrane domains were overexpressed in Escherichia coli. Western-blot analysis with antibodies against recombinant products showed secretion of parasite proteins from different functional categories into the infected host cell. Secretion of parasite hexokinase and α/β-hydrolase was confirmed by immunofluorescence microscopy. In addition, this method showed specific accumulation of A. locustae hexokinase in host nuclei. Expression of hexokinase, trehalase, and two leucine-rich repeat proteins without any exogenous signal peptide led to their secretion in the yeast Pichia pastoris. In contrast, α/β-hydrolase was not found in the culture medium, though a significant amount of this enzyme accumulated in the yeast membrane fraction. These results suggest that microsporidia possess a broad set of enzymes and regulatory proteins secreted into infected cells to control host metabolic processes and molecular programs. PMID:24705470

  11. Fluorescence Activated Cell Sorting of Rickettsia prowazekii-Infected Host Cells Based on Bacterial Burden and Early Detection of Fluorescent Rickettsial Transformants

    PubMed Central

    Driskell, Lonnie O.; Tucker, Aimee M.; Woodard, Andrew; Wood, Raphael R.; Wood, David O.

    2016-01-01

    Rickettsia prowazekii, the causative agent of epidemic typhus, is an obligate intracellular bacterium that replicates only within the cytosol of a eukaryotic host cell. Despite the barriers to genetic manipulation that such a life style creates, rickettsial mutants have been generated by transposon insertion as well as by homologous recombination mechanisms. However, progress is hampered by the length of time required to identify and isolate R. prowazekii transformants. To reduce the time required and variability associated with propagation and harvesting of rickettsiae for each transformation experiment, characterized frozen stocks were used to generate electrocompetent rickettsiae. Transformation experiments employing these rickettsiae established that fluorescent rickettsial populations could be identified using a fluorescence activated cell sorter within one week following electroporation. Early detection was improved with increasing amounts of transforming DNA. In addition, we demonstrate that heterogeneous populations of rickettsiae-infected cells can be sorted into distinct sub-populations based on the number of rickettsiae per cell. Together our data suggest the combination of fluorescent reporters and cell sorting represent an important technical advance that will facilitate isolation of distinct R. prowazekii mutants and allow for closer examination of the effects of infection on host cells at various infectious burdens. PMID:27010457

  12. Proteomic Analyses of Intracellular Salmonella enterica Serovar Typhimurium Reveal Extensive Bacterial Adaptations to Infected Host Epithelial Cells

    PubMed Central

    Liu, Yanhua; Zhang, Qiufeng; Hu, Mo; Yu, Kaiwen; Fu, Jiaqi; Zhou, Fan

    2015-01-01

    Salmonella species can gain access into nonphagocytic cells, where the bacterium proliferates in a unique membrane-bounded compartment. In order to reveal bacterial adaptations to their intracellular niche, here we conducted the first comprehensive proteomic survey of Salmonella isolated from infected epithelial cells. Among ∼3,300 identified bacterial proteins, we found that about 100 proteins were significantly altered at the onset of Salmonella intracellular replication. In addition to substantially increased iron-uptake capacities, bacterial high-affinity manganese and zinc transporters were also upregulated, suggesting an overall limitation of metal ions in host epithelial cells. We also found that Salmonella induced multiple phosphate utilization pathways. Furthermore, our data suggested upregulation of the two-component PhoPQ system as well as of many downstream virulence factors under its regulation. Our survey also revealed that intracellular Salmonella has increased needs for certain amino acids and biotin. In contrast, Salmonella downregulated glycerol and maltose utilization as well as chemotaxis pathways. PMID:25939512

  13. Manipulated microenvironment in human papilloma virus-infected epithelial cells: is the CD40-CD154 pathway beneficial for host or virus?

    PubMed

    Shimauchi, Takatoshi; Piguet, Vincent

    2014-12-01

    In this issue, Tummers et al. (2014) demonstrate that high-risk human papilloma viruses (hrHPVs) attenuate the magnitude of responses to CD40 ligation and the epithelial cells' (ECs) capacity to attract leukocytes. These results suggest that hrHPVs can escape from host immune surveillance by modulating pro-inflammatory responses in infected ECs, resulting in persistent infections and potential carcinogenesis.

  14. Role of primary human alveolar epithelial cells in host defense against Francisella tularensis infection.

    PubMed

    Gentry, Megan; Taormina, Joanna; Pyles, Richard B; Yeager, Linsey; Kirtley, Michelle; Popov, Vsevolod L; Klimpel, Gary; Eaves-Pyles, Tonyia

    2007-08-01

    Francisella tularensis, an intracellular pathogen, is highly virulent when inhaled. Alveolar epithelial type I (ATI) and type II (ATII) cells line the majority of the alveolar surface and respond to inhaled pathogenic bacteria via cytokine secretion. We hypothesized that these cells contribute to the lung innate immune response to F. tularensis. Results demonstrated that the live vaccine strain (LVS) contacted ATI and ATII cells by 2 h following intranasal inoculation of mice. In culture, primary human ATI or ATII cells, grown on transwell filters, were stimulated on the apical (AP) surface with virulent F. tularensis Schu 4 or LVS. Basolateral (BL) conditioned medium (CM), collected 6 and 24 h later, was added to the BL surfaces of transwell cultures of primary human pulmonary microvasculature endothelial cells (HPMEC) prior to the addition of polymorphonuclear leukocytes (PMNs) or dendritic cells (DCs) to the AP surface. HPMEC responded to S4- or LVS-stimulated ATII, but not ATI, CM as evidenced by PMN and DC migration. Analysis of the AP and BL ATII CM revealed that both F. tularensis strains induced various levels of a variety of cytokines via NF-kappaB activation. ATII cells pretreated with an NF-kappaB inhibitor prior to F. tularensis stimulation substantially decreased interleukin-8 secretion, which did not occur through Toll-like receptor 2, 2/6, 4, or 5 stimulation. These data indicate a crucial role for ATII cells in the innate immune response to F. tularensis. PMID:17502386

  15. Lack of the programmed death-1 receptor renders host susceptible to enteric microbial infection through impairing the production of the mucosal natural killer cell effector molecules.

    PubMed

    Solaymani-Mohammadi, Shahram; Lakhdari, Omar; Minev, Ivelina; Shenouda, Steve; Frey, Blake F; Billeskov, Rolf; Singer, Steven M; Berzofsky, Jay A; Eckmann, Lars; Kagnoff, Martin F

    2016-03-01

    The programmed death-1 receptor is expressed on a wide range of immune effector cells, including T cells, natural killer T cells, dendritic cells, macrophages, and natural killer cells. In malignancies and chronic viral infections, increased expression of programmed death-1 by T cells is generally associated with a poor prognosis. However, its role in early host microbial defense at the intestinal mucosa is not well understood. We report that programmed death-1 expression is increased on conventional natural killer cells but not on CD4(+), CD8(+) or natural killer T cells, or CD11b(+) or CD11c(+) macrophages or dendritic cells after infection with the mouse pathogen Citrobacter rodentium. Mice genetically deficient in programmed death-1 or treated with anti-programmed death-1 antibody were more susceptible to acute enteric and systemic infection with Citrobacter rodentium. Wild-type but not programmed death-1-deficient mice infected with Citrobacter rodentium showed significantly increased expression of the conventional mucosal NK cell effector molecules granzyme B and perforin. In contrast, natural killer cells from programmed death-1-deficient mice had impaired expression of those mediators. Consistent with programmed death-1 being important for intracellular expression of natural killer cell effector molecules, mice depleted of natural killer cells and perforin-deficient mice manifested increased susceptibility to acute enteric infection with Citrobacter rodentium. Our findings suggest that increased programmed death-1 signaling pathway expression by conventional natural killer cells promotes host protection at the intestinal mucosa during acute infection with a bacterial gut pathogen by enhancing the expression and production of important effectors of natural killer cell function.

  16. Host response during Yersinia pestis infection of human bronchial epithelial cells involves negative regulation of autophagy and suggests a modulation of survival-related and cellular growth pathways

    PubMed Central

    Alem, Farhang; Yao, Kuan; Lane, Douglas; Calvert, Valerie; Petricoin, Emanuel F.; Kramer, Liana; Hale, Martha L.; Bavari, Sina; Panchal, Rekha G.; Hakami, Ramin M.

    2015-01-01

    Yersinia pestis (Yp) causes the re-emerging disease plague, and is classified by the CDC and NIAID as a highest priority (Category A) pathogen. Currently, there is no approved human vaccine available and advances in early diagnostics and effective therapeutics are urgently needed. A deep understanding of the mechanisms of host response to Yp infection can significantly advance these three areas. We employed the Reverse Phase Protein Microarray (RPMA) technology to reveal the dynamic states of either protein level changes or phosphorylation changes associated with kinase-driven signaling pathways during host cell response to Yp infection. RPMA allowed quantitative profiling of changes in the intracellular communication network of human lung epithelial cells at different times post infection and in response to different treatment conditions, which included infection with the virulent Yp strain CO92, infection with a derivative avirulent strain CO92 (Pgm-, Pst-), treatment with heat inactivated CO92, and treatment with LPS. Responses to a total of 111 validated antibodies were profiled, leading to discovery of 12 novel protein hits. The RPMA analysis also identified several protein hits previously reported in the context of Yp infection. Furthermore, the results validated several proteins previously reported in the context of infection with other Yersinia species or implicated for potential relevance through recombinant protein and cell transfection studies. The RPMA results point to strong modulation of survival/apoptosis and cell growth pathways during early host response and also suggest a model of negative regulation of the autophagy pathway. We find significant cytoplasmic localization of p53 and reduced LC3-I to LC3-II conversion in response to Yp infection, consistent with negative regulation of autophagy. These studies allow for a deeper understanding of the pathogenesis mechanisms and the discovery of innovative approaches for prevention, early diagnosis, and

  17. Identification and Analysis of Novel Viral and Host Dysregulated MicroRNAs in Variant Pseudorabies Virus-Infected PK15 Cells

    PubMed Central

    Liu, Fei; Zheng, Hao; Tong, Wu; Li, Guo-Xin; Tian, Qing; Liang, Chao; Li, Li-Wei; Zheng, Xu-Chen; Tong, Guang-Zhi

    2016-01-01

    Pseudorabies (PR) is one of the most devastating diseases in the pig industry. To identify changes in microRNA (miRNA) expression and post-transcriptional regulatory responses to PRV infection in porcine kidney epithelial (PK15) cells, we sequenced a small RNA (sRNA) library prepared from infected PK15 cells and compared it to a library prepared from uninfected cells using Illumina deep sequencing. Here we found 25 novel viral miRNAs by high-throughput sequencing and 20 of these miRNAs were confirmed through stem-loop RT-qPCR. Intriguingly, unlike the usual miRNAs encoded by the α-herpesviruses, which are found clustered in the large latency transcript (LLT), these novel viral miRNAs are throughout the PRV genome like β-herpesviruses. Viral miRNAs are predicted to target multiple genes and form a complex regulatory network. GO analysis on host targets of viral miRNAs were involved in complex cellular processes, including the metabolic pathway, biological regulation, stimulus response, signaling process and immune response. Moreover, 13 host miRNAs were expressed with significant difference after infection with PRV: 8 miRNAs were up-regulated and 5 miRNAs were down-regulated, which may affect viral replication in host cell. Our results provided new insight into the characteristic of miRNAs in response to PRV infection, which is significant for further study of these miRNAs function. PMID:26998839

  18. A novel co-infection model with Toxoplasma and Chlamydia trachomatis highlights the importance of host cell manipulation for nutrient scavenging.

    PubMed

    Romano, Julia D; de Beaumont, Catherine; Carrasco, Jose A; Ehrenman, Karen; Bavoil, Patrik M; Coppens, Isabelle

    2013-04-01

    Toxoplasma and Chlamydia trachomatis are obligate intracellular pathogens that have evolved analogous strategies to replicate within mammalian cells. Both pathogens are known to extensively remodel the cytoskeleton, and to recruit endocytic and exocytic organelles to their respective vacuoles. However, how important these activities are for infectivity by either pathogen remains elusive. Here, we have developed a novel co-infection system to gain insights into the developmental cycles of Toxoplasma and C. trachomatis by infecting human cells with both pathogens, and examining their respective ability to replicate and scavenge nutrients. We hypothesize that the common strategies used by Toxoplasma and Chlamydia to achieve development results in direct competition of the two pathogens for the same pool of nutrients. We show that a single human cell can harbour Chlamydia and Toxoplasma. In co-infected cells, Toxoplasma is able to divert the content of host organelles, such as cholesterol. Consequently, the infectious cycle of Toxoplasma progresses unimpeded. In contrast, Chlamydia's ability to scavenge selected nutrients is diminished, and the bacterium shifts to a stress-induced persistent growth. Parasite killing engenders an ordered return to normal chlamydial development. We demonstrate that C. trachomatis enters a stress-induced persistence phenotype as a direct result from being barred from its normal nutrient supplies as addition of excess nutrients, e.g. amino acids, leads to substantial recovery of Chlamydia growth and infectivity. Co-infection of C. trachomatis with slow growing strains of Toxoplasma or a mutant impaired in nutrient acquisition does not restrict chlamydial development. Conversely, Toxoplasma growth is halted in cells infected with the highly virulent Chlamydia psittaci. This study illustrates the key role that cellular remodelling plays in the exploitation of host intracellular resources by Toxoplasma and Chlamydia. It further highlights the

  19. Protective host immune responses to Salmonella infection.

    PubMed

    Pham, Oanh H; McSorley, Stephen J

    2015-01-01

    Salmonella enterica serovars Typhi and Paratyphi are the causative agents of human typhoid fever. Current typhoid vaccines are ineffective and are not widely used in endemic areas. Greater understanding of host-pathogen interactions during Salmonella infection should facilitate the development of improved vaccines to combat typhoid and nontyphoidal Salmonellosis. This review will focus on our current understanding of Salmonella pathogenesis and the major host immune components that participate in immunity to Salmonella infection. In addition, recent findings regarding host immune mechanisms in response to Salmonella infection will be also discussed, providing a new perspective on the utility of improved tools to study the immune response to Salmonella infections.

  20. Review on Trypanosoma cruzi: Host Cell Interaction

    PubMed Central

    de Souza, Wanderley; de Carvalho, Tecia Maria Ulisses; Barrias, Emile Santos

    2010-01-01

    Trypanosoma cruzi, the causative agent of Chagas' disease, which affects a large number of individuals in Central and South America, is transmitted to vertebrate hosts by blood-sucking insects. This protozoan is an obligate intracellular parasite. The infective forms of the parasite are metacyclic and bloodstream trypomastigote and amastigote. Metacyclic trypomastigotes are released with the feces of the insect while amastigotes and bloodstream trypomastigotes are released from the infected host cells of the vertebrate host after a complex intracellular life cycle. The recognition between parasite and mammalian host cell involves numerous molecules present in both cell types. Here, we present a brief review of the interaction between Trypanosoma cruzi and its host cells, mainly emphasizing the mechanisms and molecules that participate in the T. cruzi invasion process of the mammalian cells. PMID:20811486

  1. Parasitic worms stimulate host NADPH oxidases to produce reactive oxygen species that limit plant cell death and promote infection.

    PubMed

    Siddique, Shahid; Matera, Christiane; Radakovic, Zoran S; Hasan, M Shamim; Gutbrod, Philipp; Rozanska, Elzbieta; Sobczak, Miroslaw; Torres, Miguel Angel; Grundler, Florian M W

    2014-04-01

    Plants and animals produce reactive oxygen species (ROS) in response to infection. In plants, ROS not only activate defense responses and promote cell death to limit the spread of pathogens but also restrict the amount of cell death in response to pathogen recognition. Plants also use hormones, such as salicylic acid, to mediate immune responses to infection. However, there are long-lasting biotrophic plant-pathogen interactions, such as the interaction between parasitic nematodes and plant roots during which defense responses are suppressed and root cells are reorganized to specific nurse cell systems. In plants, ROS are primarily generated by plasma membrane-localized NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidases, and loss of NADPH oxidase activity compromises immune responses and cell death. We found that infection of Arabidopsis thaliana by the parasitic nematode Heterodera schachtii activated the NADPH oxidases RbohD and RbohF to produce ROS, which was necessary to restrict infected plant cell death and promote nurse cell formation. RbohD- and RbohF-deficient plants exhibited larger regions of cell death in response to nematode infection, and nurse cell formation was greatly reduced. Genetic disruption of SID2, which is required for salicylic acid accumulation and immune activation in nematode-infected plants, led to the increased size of nematodes in RbohD- and RbohF-deficient plants, but did not decrease plant cell death. Thus, by stimulating NADPH oxidase-generated ROS, parasitic nematodes fine-tune the pattern of plant cell death during the destructive root invasion and may antagonize salicylic acid-induced defense responses during biotrophic life stages.

  2. The impact of α-toxin on host cell plasma membrane permeability and cytokine expression during human blood infection by CA-MRSA USA300

    PubMed Central

    Nygaard, Tyler K.; Pallister, Kyler B.; Zurek, Oliwia W.; Voyich, Jovanka M.

    2013-01-01

    This investigation examines the influence of α-toxin (Hla) expression by CA-MRSA on host immune cell integrity and cytokine expression during infection of human blood. Flow cytometry analysis of human blood infected by Staphylococcus aureus PFGE type USA300 or a USA300Δhla demonstrated that Hla expression significantly increased plasma membrane permeability of human CD14+ monocytes. The increased susceptibility of human CD14+ monocytes to Hla toxicity paralleled the high cell-surface expression on these cell types of ADAM10. USA300 rapidly associated with PMNs and monocytes but not T cells following inoculation of human blood. Transcription analysis indicated a strong up-regulation of proinflammatory cytokine transcription following infection of human blood by USA300 and USA300Δhla. CBAs and ELISAs determined that IL-6, IL-10, TNF-α, IFN-γ, IL-1β, IL-8, and IL-4 are significantly up-regulated during the initial phases of human blood infection by USA300 relative to mock-infected blood but failed to distinguish any significant differences in secreted cytokine protein concentrations during infection by USA300Δhla relative to USA300. Collectively, these findings demonstrate that expression of Hla by USA300 has a significant impact on human CD14+ monocyte plasma membrane integrity but is not exclusively responsible for the proinflammatory cytokine profile induced by USA300 during the initial stages of human blood infection. PMID:24026286

  3. The impact of α-toxin on host cell plasma membrane permeability and cytokine expression during human blood infection by CA-MRSA USA300.

    PubMed

    Nygaard, Tyler K; Pallister, Kyler B; Zurek, Oliwia W; Voyich, Jovanka M

    2013-11-01

    This investigation examines the influence of α-toxin (Hla) expression by CA-MRSA on host immune cell integrity and cytokine expression during infection of human blood. Flow cytometry analysis of human blood infected by Staphylococcus aureus PFGE type USA300 or a USA300Δhla demonstrated that Hla expression significantly increased plasma membrane permeability of human CD14(+) monocytes. The increased susceptibility of human CD14(+) monocytes to Hla toxicity paralleled the high cell-surface expression on these cell types of ADAM10. USA300 rapidly associated with PMNs and monocytes but not T cells following inoculation of human blood. Transcription analysis indicated a strong up-regulation of proinflammatory cytokine transcription following infection of human blood by USA300 and USA300Δhla. CBAs and ELISAs determined that IL-6, IL-10, TNF-α, IFN-γ, IL-1β, IL-8, and IL-4 are significantly up-regulated during the initial phases of human blood infection by USA300 relative to mock-infected blood but failed to distinguish any significant differences in secreted cytokine protein concentrations during infection by USA300Δhla relative to USA300. Collectively, these findings demonstrate that expression of Hla by USA300 has a significant impact on human CD14(+) monocyte plasma membrane integrity but is not exclusively responsible for the proinflammatory cytokine profile induced by USA300 during the initial stages of human blood infection.

  4. Host Responses and Regulation by NFκB Signaling in the Liver and Liver Epithelial Cells Infected with A Novel Tick-borne Bunyavirus

    PubMed Central

    Sun, Qiyu; Jin, Cong; Zhu, Lili; Liang, Mifang; Li, Chuan; Cardona, Carol J.; Li, Dexin; Xing, Zheng

    2015-01-01

    Infection in humans by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus transmitted by ticks, is often associated with pronounced liver damage, especially in fatal cases. Little has been known, however, about how liver cells respond to SFTSV and how the response is regulated. In this study we report that proinflammatory cytokines were induced in liver tissues of C57/BL6 mice infected with SFTSV, which may cause tissue necrosis in mice. Human liver epithelial cells were susceptible to SFTSV and antiviral interferon (IFN) and IFN-inducible proteins were induced upon infection. We observed that infection of liver epithelial cells led to significant increases in proinflammatory cytokines and chemokines, including IL-6, RANTES, IP-10, and MIP-3a, which were regulated by NFκB signaling, and the activation of NFκB signaling during infection promoted viral replication in liver epithelial cells. Viral nonstructural protein NSs was inhibitory to the induction of IFN-β, but interestingly, NFκB activation was enhanced in the presence of NSs. Therefore, NSs plays dual roles in the suppression of antiviral IFN-β induction as well as the promotion of proinflammatory responses. Our findings provide the first evidence for elucidating host responses and regulation in liver epithelial cells infected by an emerging bunyavirus. PMID:26134299

  5. Host Responses and Regulation by NFκB Signaling in the Liver and Liver Epithelial Cells Infected with A Novel Tick-borne Bunyavirus.

    PubMed

    Sun, Qiyu; Jin, Cong; Zhu, Lili; Liang, Mifang; Li, Chuan; Cardona, Carol J; Li, Dexin; Xing, Zheng

    2015-01-01

    Infection in humans by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus transmitted by ticks, is often associated with pronounced liver damage, especially in fatal cases. Little has been known, however, about how liver cells respond to SFTSV and how the response is regulated. In this study we report that proinflammatory cytokines were induced in liver tissues of C57/BL6 mice infected with SFTSV, which may cause tissue necrosis in mice. Human liver epithelial cells were susceptible to SFTSV and antiviral interferon (IFN) and IFN-inducible proteins were induced upon infection. We observed that infection of liver epithelial cells led to significant increases in proinflammatory cytokines and chemokines, including IL-6, RANTES, IP-10, and MIP-3a, which were regulated by NFκB signaling, and the activation of NFκB signaling during infection promoted viral replication in liver epithelial cells. Viral nonstructural protein NSs was inhibitory to the induction of IFN-β, but interestingly, NFκB activation was enhanced in the presence of NSs. Therefore, NSs plays dual roles in the suppression of antiviral IFN-β induction as well as the promotion of proinflammatory responses. Our findings provide the first evidence for elucidating host responses and regulation in liver epithelial cells infected by an emerging bunyavirus.

  6. Host/parasite relationship in the in vitro infection of rat gliocytes by Neospora caninum: evaluation of cell respiration.

    PubMed

    Pinheiro, Alexandre M; Santos, Cláudia Valle; Costa, Maria de Fátima D; Rodrigues, Luiz Erlon A

    2007-08-01

    Neospora caninum is a protozoon that causes abortion in cattle and neuromuscular lesions in dogs, with the formation of cysts mainly in the central nervous system. Since N. caninum is an intracellular parasite with tropism for the cells of nervous system, this study evaluated the respiratory metabolism of glial cells infected by this* parasite. Glial cultures obtained from the cerebral cortex of newborn rats were kept in DMEM enriched with 10% fetal bovine serum, 1 mM pyruvic acid and 2 mM of L-glutamine. They were infected at a ratio of approximately 1:1 (cell/parasite). Oxygen consumption was evaluated by polarography in the non infected and N. caninum infected groups, 24 and 72 h following infection. Glial cell respiration after 24 and 72 h was 307.2 +/- 34.7 and 308.9 +/- 64.1 microL of oxygen per mug of total protein per minute, and 566.2 +/- 54.6 and 579 +/- 117.5 microL O2/microg of total protein/minute in the control and infected groups, respectively. These results show that N. caninum does not interfere with glial respiration in vitro.

  7. Small RNA Profiling in Dengue Virus 2-Infected Aedes Mosquito Cells Reveals Viral piRNAs and Novel Host miRNAs

    PubMed Central

    Miesen, Pascal; Ivens, Alasdair; Buck, Amy H.; van Rij, Ronald P.

    2016-01-01

    In Aedes mosquitoes, infections with arthropod-borne viruses (arboviruses) trigger or modulate the expression of various classes of viral and host-derived small RNAs, including small interfering RNAs (siRNAs), PIWI interacting RNAs (piRNAs), and microRNAs (miRNAs). Viral siRNAs are at the core of the antiviral RNA interference machinery, one of the key pathways that limit virus replication in invertebrates. Besides siRNAs, Aedes mosquitoes and cells derived from these insects produce arbovirus-derived piRNAs, the best studied examples being viruses from the Togaviridae or Bunyaviridae families. Host miRNAs modulate the expression of a large number of genes and their levels may change in response to viral infections. In addition, some viruses, mostly with a DNA genome, express their own miRNAs to regulate host and viral gene expression. Here, we perform a comprehensive analysis of both viral and host-derived small RNAs in Aedes aegypti Aag2 cells infected with dengue virus 2 (DENV), a member of the Flaviviridae family. Aag2 cells are competent in producing all three types of small RNAs and provide a powerful tool to explore the crosstalk between arboviral infection and the distinct RNA silencing pathways. Interestingly, besides the well-characterized DENV-derived siRNAs, a specific population of viral piRNAs was identified in infected Aag2 cells. Knockdown of Piwi5, Ago3 and, to a lesser extent, Piwi6 results in reduction of vpiRNA levels, providing the first genetic evidence that Aedes PIWI proteins produce DENV-derived small RNAs. In contrast, we do not find convincing evidence for the production of virus-derived miRNAs. Neither do we find that host miRNA expression is strongly changed upon DENV2 infection. Finally, our deep-sequencing analyses detect 30 novel Aedes miRNAs, complementing the repertoire of regulatory small RNAs in this important vector species. PMID:26914027

  8. Human α-Defensins Inhibit BK Virus Infection by Aggregating Virions and Blocking Binding to Host Cells*

    PubMed Central

    Dugan, Aisling S.; Maginnis, Melissa S.; Jordan, Joslynn A.; Gasparovic, Megan L.; Manley, Kate; Page, Rebecca; Williams, Geoffrey; Porter, Edith; O'Hara, Bethany A.; Atwood, Walter J.

    2008-01-01

    BK virus (BKV) is a polyomavirus that establishes a lifelong persistence in most humans and is a major impediment to success of kidney grafts. The function of the innate immune system in BKV infection and pathology has not been investigated. Here we examine the role of antimicrobial defensins in BKV infection of Vero cells. Our data show that α-defensin human neutrophil protein 1 (HNP1) and human α-defensin 5 (HD5) inhibit BKV infection by targeting an early event in the viral lifecycle. HD5 treatment of BKV reduced viral attachment to cells, whereas cellular treatment with HD5 did not. Colocalization studies indicated that HD5 interacts directly with BKV. Ultrastructural analysis revealed HD5-induced aggregation of virions. HD5 also inhibited infection of cells by other related polyomaviruses. This is the first study to demonstrate polyomavirus sensitivity to defensins. We also show a novel mechanism whereby HD5 binds to BKV leading to aggregation of virion particles preventing normal virus binding to the cell surface and uptake into cells. PMID:18782756

  9. Penetration of Bdellovibrio bacteriovorus into Host Cells

    PubMed Central

    Abram, Dinah; e Melo, J. Castro; Chou, D.

    1974-01-01

    Electron microscopy reveals that, in Bdellovibrio infection, after the formation of a passage pore in the host cell wall, the differentiated parasite penetration pole is associated with the host protoplast. This firm contact persists throughout the parasite penetration and after this process is completed. In penetrated hosts this contact is also apparent by phase microscopy. The association between the walls of the parasite and the host at the passage pore, on the other hand, is transient. Bdellovibrio do not penetrate hosts whose protoplast and cell walls are separated by plasmolysis, or in which the membrane-wall relationship is affected by low turgor pressure. It is concluded, therefore, that for penetration to occur it is essential that the host protoplast be within reach of the parasite, so that a firm contact can be established between them. A penetration mechanism is proposed that is effected by forces generated by fluxes of water and solutes due to structural changes in the infected host envelope. These forces cause a differential expansion of the host protoplast and cell wall and their separation from each other around the entry site, while the parasite remains firmly anchored to the host protoplast. Consequently, the parasite ends up enclosed in the expanded host periplasm. The actual entry, therefore, is a passive act of the parasite. Images PMID:4208138

  10. RNA interference silences Microplitis demolitor bracovirus genes and implicates glc1.8 in disruption of adhesion in infected host cells.

    PubMed

    Beck, Markus; Strand, Michael R

    2003-09-30

    The family Polydnaviridae consists of ds-DNA viruses that are symbiotically associated with certain parasitoid wasps. PDVs are transmitted vertically but also are injected by wasps into hosts where they cause several physiological alterations including immunosuppression. The PDV genes responsible for mediating immunosuppression and other host alterations remain poorly characterized in large measure because viral mutants cannot be produced to study gene function. Here we report the use of RNA interference (RNAi) to specifically silence the glc1.8 and egf1.0 genes from Microplitis demolitor bracovirus (MdBV) in High Five cells derived from the lepidopteran Trichoplusia ni. Dose-response studies indicated that MdBV infects High Five cells and blocks the ability of these cells to adhere to culture plates. This response was very similar to what occurs in two classes of hemocytes, granular cells, and plasmatocytes, after infection by MdBV. Screening of monoclonal antibody (mAb) markers that distinguish different classes of lepidopteran hemocytes indicated that High Five cells cross-react with three mAbs that recognize granular cells from T. ni. Double-stranded RNA (dsRNA) complementary to glc1.8 specifically silenced glc1.8 expression and rescued the adhesive phenotype of High Five cells. Reciprocally, dsRNA complementary to egf1.0 silenced egf1.0 expression but had no effect on adhesion. The simplicity and potency of RNAi could be extremely useful for analysis of other PDV genes.

  11. High-Throughput Differentiation and Screening of a Library of Mutant Stem Cell Clones Defines New Host-Based Genes Involved in Rabies Virus Infection.

    PubMed

    Wallis, Deeann; Loesch, Kimberly; Galaviz, Stacy; Sun, Qingan; DeJesus, Michael; Ioerger, Thomas; Sacchettini, James C

    2015-08-01

    We used a genomic library of mutant murine embryonic stem cells (ESCs) and report the methodology required to simultaneously culture, differentiate, and screen more than 3,200 heterozygous mutant clones to identify host-based genes involved in both sensitivity and resistance to rabies virus infection. Established neuronal differentiation protocols were miniaturized such that many clones could be handled simultaneously, and molecular markers were used to show that the resultant cultures were pan-neuronal. Next, we used a green fluorescent protein (GFP) labeled rabies virus to develop, validate, and implement one of the first host-based, high-content, high-throughput screens for rabies virus. Undifferentiated cell and neuron cultures were infected with GFP-rabies and live imaging was used to evaluate GFP intensity at time points corresponding to initial infection/uptake and early and late replication. Furthermore, supernatants were used to evaluate viral shedding potential. After repeated testing, 63 genes involved in either sensitivity or resistance to rabies infection were identified. To further explore hits, we used a completely independent system (siRNA) to show that reduction in target gene expression leads to the observed phenotype. We validated the immune modulatory gene Unc13d and the dynein adapter gene Bbs4 by treating wild-type ESCs and primary neurons with siRNA; treated cultures were resistant to rabies infection/replication. Overall, the potential of such in vitro functional genomics screens in stem cells adds additional value to other libraries of stem cells. This technique is applicable to any bacterial or virus interactome and any cell or tissue types that can be differentiated from ESCs.

  12. Poxvirus host cell entry.

    PubMed

    Schmidt, Florian Ingo; Bleck, Christopher Karl Ernst; Mercer, Jason

    2012-02-01

    Poxviruses are characterized by their large size, complex composition, and cytoplasmic life cycle. They produce two types of infectious particles: mature virions (MVs) and extracellular virions (EVs). Both MVs and EVs of vaccinia virus, the model poxvirus, take advantage of host cell endocytosis for internalization: they activate macropinocytosis-the most suitable form of endocytosis for large particles. Although largely dependent on the same cellular machinery, MV and EV entry differs with regard to the mechanisms used to trigger macropinocytosis and to undergo fusion. While EVs have to shed an additional membrane to expose the fusion complex, MV fusion requires the inactivation of fusion inhibitory proteins absent in EVs. This review highlights recent advances in the understanding of poxvirus MV and EV cell entry. PMID:22440962

  13. IL-17A and Th17 Cells in Lung Inflammation: An Update on the Role of Th17 Cell Differentiation and IL-17R Signaling in Host Defense against Infection

    PubMed Central

    Wu, Reen

    2013-01-01

    The significance of Th17 cells and interleukin- (IL-)17A signaling in host defense and disease development has been demonstrated in various infection and autoimmune models. Numerous studies have indicated that Th17 cells and its signature cytokine IL-17A are critical to the airway's immune response against various bacteria and fungal infection. Cytokines such as IL-23, which are involved in Th17 differentiation, play a critical role in controlling Klebsiella pneumonia (K. pneumonia) infection. IL-17A acts on nonimmune cells in infected tissues to strengthen innate immunity by inducing the expression of antimicrobial proteins, cytokines, and chemokines. Mice deficient in IL-17 receptor (IL-17R) expression are susceptible to infection by various pathogens. In this review, we summarize the recent advances in unraveling the mechanism behind Th17 cell differentiation, IL-17A/IL-17R signaling, and also the importance of IL-17A in pulmonary infection. PMID:23956759

  14. Dictyostelium host response to legionella infection: strategies and assays.

    PubMed

    Bozzaro, Salvatore; Peracino, Barbara; Eichinger, Ludwig

    2013-01-01

    The professional phagocyte Dictyostelium discoideum is a simple eukaryotic microorganism, whose natural habitat is deciduous forest soil and decaying leaves, where the amoebae feed on bacteria and grow as separate, independent, single cells. In the last decade, the organism has been successfully used as a host for several human pathogens, including Legionella pneumophila, Mycobacterium avium and Mycobacterium marinum,Pseudomonas aeruginosa, Klebsiella pneumoniae, Cryptococcus neoformans, and Salmonella typhimurium. To dissect the complex cross-talk between host and pathogen Dictyostelium offers easy cultivation, a high quality genome sequence and excellent molecular genetic and biochemical tools. Dictyostelium cells are also extremely suitable for cell biological studies, which in combination with in vivo expression of fluorescence-tagged proteins allow investigating the dynamics of bacterial uptake and infection. Inactivation of genes by homologous recombination as well as gene rescue and overexpression are well established and a large mutant collection is available at the Dictyostelium stock center, favoring identification of host resistance or susceptibility genes. Here, we briefly introduce the organism, address the value of Dictyostelium as model host, describe strategies to identify host cell factors important for infection followed by protocols for cell culture and storage, uptake and infection, and confocal microscopy of infected cells. PMID:23150412

  15. Dictyostelium host response to legionella infection: strategies and assays.

    PubMed

    Bozzaro, Salvatore; Peracino, Barbara; Eichinger, Ludwig

    2013-01-01

    The professional phagocyte Dictyostelium discoideum is a simple eukaryotic microorganism, whose natural habitat is deciduous forest soil and decaying leaves, where the amoebae feed on bacteria and grow as separate, independent, single cells. In the last decade, the organism has been successfully used as a host for several human pathogens, including Legionella pneumophila, Mycobacterium avium and Mycobacterium marinum,Pseudomonas aeruginosa, Klebsiella pneumoniae, Cryptococcus neoformans, and Salmonella typhimurium. To dissect the complex cross-talk between host and pathogen Dictyostelium offers easy cultivation, a high quality genome sequence and excellent molecular genetic and biochemical tools. Dictyostelium cells are also extremely suitable for cell biological studies, which in combination with in vivo expression of fluorescence-tagged proteins allow investigating the dynamics of bacterial uptake and infection. Inactivation of genes by homologous recombination as well as gene rescue and overexpression are well established and a large mutant collection is available at the Dictyostelium stock center, favoring identification of host resistance or susceptibility genes. Here, we briefly introduce the organism, address the value of Dictyostelium as model host, describe strategies to identify host cell factors important for infection followed by protocols for cell culture and storage, uptake and infection, and confocal microscopy of infected cells.

  16. Polymicrobial-Host Interactions during Infection.

    PubMed

    Tay, Wei Hong; Chong, Kelvin Kian Long; Kline, Kimberly A

    2016-08-28

    Microbial pathogenesis research has, historically, focused on the study of infections as monomicrobial events. However, the advent of next generation sequencing and culture-independent identification methods has revealed that many, if not most, infections are polymicrobial either in origin or in manifestation. Polymicrobial infections are often associated with increased infection severity and poorer patient outcome. Multiple infecting microbes can interact synergistically to induce virulence traits, alter the infected niche, or modulate the host immune response, all of which can promote polymicrobial infection. Importantly, a polymicrobial environment at the time of inoculation, consisting of multiple pathogens or pathogens in combination with the native microbiota, can contribute to the pathogenic progression of a single predominant organism at the time of diagnosis. Hence, in order to completely understand and elucidate the impact of these polymicrobial interactions on infection outcomes, a thorough examination of the entire microbial community present throughout the pathogenic cascade is required: from the time of inoculation to symptomology to resolution. In this review, we highlight the themes of metabolite exploitation, immune modulation, niche optimization, and virulence induction that contribute to polymicrobial infections. We focus on recent literature about microbe-microbe and microbe-host interactions that promote polymicrobial infections with an emphasis on understanding these interactions to identify better interventions for these sometimes complex infections. PMID:27170548

  17. The Coevolutionary Period of Wolbachia pipientis Infecting Drosophila ananassae and Its Impact on the Evolution of the Host Germline Stem Cell Regulating Genes

    PubMed Central

    Choi, Jae Young; Aquadro, Charles F.

    2014-01-01

    The endosymbiotic bacteria Wolbachia pipientis is known to infect a wide range of arthropod species yet less is known about the coevolutionary history it has with its hosts. Evidence of highly identical W. pipientis strains in evolutionary divergent hosts suggests horizontal transfer between hosts. For example, Drosophila ananassae is infected with a W. pipientis strain that is nearly identical in sequence to a strain that infects both D. simulans and D. suzukii, suggesting recent horizontal transfer among these three species. However, it is unknown whether the W. pipientis strain had recently invaded all three species or a more complex infectious dynamic underlies the horizontal transfers. Here, we have examined the coevolutionary history of D. ananassae and its resident W. pipientis to infer its period of infection. Phylogenetic analysis of D. ananassae mitochondrial DNA and W. pipientis DNA sequence diversity revealed the current W. pipientis infection is not recent. In addition, we examined the population genetics and molecular evolution of several germline stem cell (GSC) regulating genes of D. ananassae. These studies reveal significant evidence of recent and long-term positive selection at stonewall in D. ananassae, whereas pumillio showed patterns of variation consistent with only recent positive selection. Previous studies had found evidence for adaptive evolution of two key germline differentiation genes, bag of marbles (bam) and benign gonial cell neoplasm (bgcn), in D. melanogaster and D. simulans and proposed that the adaptive evolution at these two genes was driven by arms race between the host GSC and W. pipientis. However, we did not find any statistical departures from a neutral model of evolution for bam and bgcn in D. ananassae despite our new evidence that this species has been infected with W. pipientis for a period longer than the most recent infection in D. melanogaster. In the end, analyzing the GSC regulating genes individually showed two

  18. Formation of a host range mutant of the lymphotropic strain of minute virus of mice during persistent infection in mouse L cells.

    PubMed Central

    Ron, D; Tattersall, P; Tal, J

    1984-01-01

    Minute virus of mice (i), the lymphotropic strain of minute virus of mice, established a persistent infection in normally restrictive L cells. The carrier state, which lasted 150 days, exhibited three clearly distinguishable stages. During the early stage (days 1 to 10 postinfection), small amounts of virus were formed. A "crisis" then developed that lasted 50 to 60 days and was characterized by massive cell lysis and high titers of virus. This was followed by a 70- to 80-day period in which small but stable quantities of virus were produced. Virus shed by the carrier culture during the latter phase had acquired an altered host range, namely, it had lost its ability to replicate in T-lymphocyte cell lines and had adapted to growth in L cells. Virus isolated at this time from a single plaque in L cells, designated hr301, was shown to possess similar host range properties. No differences, however, could be found between the DNAs of minute virus of mice (i) and of hr301 by restriction enzyme analysis, suggesting that the mutation that affected the viral host range did not involve an extensive region of the viral genome. Images PMID:6090711

  19. Gene expression profiling of the host response to HIV-1 B, C, or A/E infection in monocyte-derived dendritic cells

    SciTech Connect

    Solis, Mayra; Wilkinson, Peter; Romieu, Raphaelle; Hernandez, Eduardo; Wainberg, Mark A.; Hiscott, John . E-mail: john.hiscott@mcgill.ca

    2006-08-15

    Dendritic cells (DC) are among the first targets of human immunodeficiency virus type-1 (HIV-1) infection and in turn play a crucial role in viral transmission to T cells and in the regulation of the immune response. The major group of HIV-1 has diversified genetically based on variation in env sequences and comprise at least 11 subtypes. Because little is known about the host response elicited against different HIV-1 clade isolates in vivo, we sought to use gene expression profiling to identify genes regulated by HIV-1 subtypes B, C, and A/E upon de novo infection of primary immature monocyte-derived DC (iMDDCs). A total of 3700 immune-related genes were subjected to a significance analysis of microarrays (SAM); 656 genes were selected as significant and were further divided into 8 functional categories. Regardless of the time of infection, 20% of the genes affected by HIV-1 were involved in signal transduction, followed by 14% of the genes identified as transcription-related genes, and 7% were classified as playing a role in cell proliferation and cell cycle. Furthermore, 7% of the genes were immune response genes. By 72 h postinfection, genes upregulated by subtype B included the inhibitor of the matrix metalloproteinase TIMP2 and the heat shock protein 40 homolog (Hsp40) DNAJB1, whereas the IFN inducible gene STAT1, the MAPK1/ERK2 kinase regulator ST5, and the chemokine CXCL3 and SHC1 genes were induced by subtypes C and A/E. These analyses distinguish a temporally regulated host response to de novo HIV-1 infection in primary dendritic cells.

  20. The transient inability of the conjugating female cell to host 186 infection explains the absence of zygotic induction for 186.

    PubMed Central

    Woods, W H; Egan, B

    1981-01-01

    In an Hfr(186) X F- cross, the 186 prophage on the incoming male chromosome is not induced, despite the fact that prophage 186 can be induced by other means (W. H. Woods and J.B. Egan, J Virol. 14:1349-1356, 1974). We show here that the conjugating female is temporarily inhibitory to infection by 186, and this delay, we postulate, enables cI repression to be reestablished before the female cell recovers its 186 sensitivity. PMID:7033561

  1. The virion host shutoff RNase plays a key role in blocking the activation of protein kinase R in cells infected with herpes simplex virus 1.

    PubMed

    Sciortino, Maria Teresa; Parisi, Tiziana; Siracusano, Gabriel; Mastino, Antonio; Taddeo, Brunella; Roizman, Bernard

    2013-03-01

    Earlier studies have shown that active MEK blocks the activation of protein kinase R (PKR), a component of antiviral innate immune responses. In this report we show that the herpes simplex virus 1 virion host shutoff (VHS) RNase protein and MEK (mitogen-activated protein kinase kinase) act cooperatively in blocking the activation of PKR. This conclusion is based on the following. (i) In contrast to viral gene expression in the parental cell line or a cell line expressing a constitutively active MEK, the replication of a VHS mutant is particularly impaired in cells expressing dominant negative MEK. In this cell line PKR is activated by phosphorylation, and the accumulation of several viral proteins is delayed. (ii) In transfected cells, wild-type VHS blocked the activation of PKR, whereas PKR was activated in cells transfected with a mutant VHS or with plasmids encoding the VHS RNase and VP16 and VP22, the two viral proteins that neutralize the RNase activity of VHS. The results suggest that early in infection the VHS RNase degrades RNAs that activate PKR. Coupled with published data, the results suggest that inhibition of activation of PKR or its effect on viral replication is staged early in infection by VHS, postsynthesis of VP16 and VP22 by the γ(1)34.5 protein, and very late in infection by the U(S)11 protein.

  2. Cell division and density of symbiotic Chlorella variabilis of the ciliate Paramecium bursaria is controlled by the host's nutritional conditions during early infection process.

    PubMed

    Kodama, Yuuki; Fujishima, Masahiro

    2012-10-01

    The association of ciliate Paramecium bursaria with symbiotic Chlorella sp. is a mutualistic symbiosis. However, both the alga-free paramecia and symbiotic algae can still grow independently and can be reinfected experimentally by mixing them. Effects of the host's nutritional conditions against the symbiotic algal cell division and density were examined during early reinfection. Transmission electron microscopy revealed that algal cell division starts 24 h after mixing with alga-free P. bursaria, and that the algal mother cell wall is discarded from the perialgal vacuole membrane, which encloses symbiotic alga. Labelling of the mother cell wall with Calcofluor White Stain, a cell-wall-specific fluorochrome, was used to show whether alga had divided or not. Pulse labelling of alga-free P. bursaria cells with Calcofluor White Stain-stained algae with or without food bacteria for P. bursaria revealed that the fluorescence of Calcofluor White Stain in P. bursaria with bacteria disappeared within 3 days after mixing, significantly faster than without bacteria. Similar results were obtained both under constant light and dark conditions. This report is the first describing that the cell division and density of symbiotic algae of P. bursaria are controlled by the host's nutritional conditions during early infection.

  3. Hepatitis E genotype 4 virus from feces of monkeys infected experimentally can be cultured in PLC/PRF/5 cells and upregulate host interferon-inducible genes.

    PubMed

    Zhang, Feng; Qi, Ying; Harrison, Tim J; Luo, Baobin; Zhou, Yan; Li, Xiuhua; Song, Aijing; Huang, Weijin; Wang, Youchun

    2014-10-01

    The understanding of the interaction between hepatitis E virus (HEV) and its host cells has been impeded greatly by the absence of a cell culture system. In this study, an efficient cultivation method was developed in PLC/PRF/5 cells for HEV genotype 4 from the feces of monkeys infected experimentally. Compared to minimal essential medium (MEM), mixed Dulbecco's Modified Eagle's Medium (DMEM)/M199 improved the infection efficiency of HEV in PLC/PRF/5 cells. The incubation time and temperature were set at 6 hr and 40°C, respectively. Compared to a 100% ELISA positive ratio (EPR) of 1 × 10(6)  copies/ml HEV inoculated flasks, the ELISA positive ratio was 100%, 75%, 37.5%, and 100% for flasks inoculated with HEV incubated for 30 min under the conditions of pH 3.0, pH 11.0, 56°C and delipidation treatment, respectively. Gene expression profiles of HEV inoculated and control PLC/PRF/5 cells were assayed using a microarray. Four interferon-inducible genes, IFI27, IFI6, Mx1, and CMPK2, were up-regulated during HEV-infection. Furthermore, the replication of HEV was inhibited at 3-14 days after treatment with 500 IU/ml IFN-α2b.

  4. Structural basis of the interaction of a Trypanosoma cruzi surface molecule implicated in oral infection with host cells and gastric mucin.

    PubMed

    Cortez, Cristian; Yoshida, Nobuko; Bahia, Diana; Sobreira, Tiago J P

    2012-01-01

    Host cell invasion and dissemination within the host are hallmarks of virulence for many pathogenic microorganisms. As concerns Trypanosoma cruzi, which causes Chagas disease, the insect vector-derived metacyclic trypomastigotes (MT) initiate infection by invading host cells, and later blood trypomastigotes disseminate to diverse organs and tissues. Studies with MT generated in vitro and tissue culture-derived trypomastigotes (TCT), as counterparts of insect-borne and bloodstream parasites, have implicated members of the gp85/trans-sialidase superfamily, MT gp82 and TCT Tc85-11, in cell invasion and interaction with host factors. Here we analyzed the gp82 structure/function characteristics and compared them with those previously reported for Tc85-11. One of the gp82 sequences identified as a cell binding site consisted of an α-helix, which connects the N-terminal β-propeller domain to the C-terminal β-sandwich domain where the second binding site is nested. In the gp82 structure model, both sites were exposed at the surface. Unlike gp82, the Tc85-11 cell adhesion sites are located in the N-terminal β-propeller region. The gp82 sequence corresponding to the epitope for a monoclonal antibody that inhibits MT entry into target cells was exposed on the surface, upstream and contiguous to the α-helix. Located downstream and close to the α-helix was the gp82 gastric mucin binding site, which plays a central role in oral T. cruzi infection. The sequences equivalent to Tc85-11 laminin-binding sites, which have been associated with the parasite ability to overcome extracellular matrices and basal laminae, was poorly conserved in gp82, compatible with its reduced capacity to bind laminin. Our study indicates that gp82 is structurally suited for MT to initiate infection by the oral route, whereas Tc85-11, with its affinity for laminin, would facilitate the parasite dissemination through diverse organs and tissues.

  5. Quantitative proteomic analysis of HIV-1 infected CD4+ T cells reveals an early host response in important biological pathways: Protein synthesis, cell proliferation, and T-cell activation

    SciTech Connect

    Navare, Arti T.; Sova, Pavel; Purdy, David E.; Weiss, Jeffrey M.; Wolf-Yadlin, Alejandro; Korth, Marcus J.; Chang, Stewart T.; Proll, Sean C.; Jahan, Tahmina A.; Krasnoselsky, Alexei L.; Palermo, Robert E.; Katze, Michael G.

    2012-07-20

    Human immunodeficiency virus (HIV-1) depends upon host-encoded proteins to facilitate its replication while at the same time inhibiting critical components of innate and/or intrinsic immune response pathways. To characterize the host cell response on protein levels in CD4+ lymphoblastoid SUP-T1 cells after infection with HIV-1 strain LAI, we used mass spectrometry (MS)-based global quantitation with iTRAQ (isobaric tag for relative and absolute quantification). We found 266, 60 and 22 proteins differentially expressed (DE) (P-value{<=}0.05) at 4, 8, and 20 hours post-infection (hpi), respectively, compared to time-matched mock-infected samples. The majority of changes in protein abundance occurred at an early stage of infection well before the de novo production of viral proteins. Functional analyses of these DE proteins showed enrichment in several biological pathways including protein synthesis, cell proliferation, and T-cell activation. Importantly, these early changes before the time of robust viral production have not been described before.

  6. Host genomics and control of tuberculosis infection.

    PubMed

    Cobat, A; Orlova, M; Barrera, L F; Schurr, E

    2013-01-01

    Tuberculosis (TB), caused by the human pathogenic bacterium Mycobacterium tuberculosis, poses a major global health problem. The tubercle bacillus is transmitted from person to person by aerosol, but only a proportion of those in contact with infectious aerosol particles will become infected. If infection occurs, less than 10% of those infected will develop clinical signs of TB, while the majority will develop latent TB infection (LTBI). The identification and treatment of LTBI persons is a major aspect of TB control, especially in low-incidence, highly developed nations. In the absence of a gold standard test for latent TB, infection is inferred with the help of either the in vivo tuberculin skin test or in vitro interferon gamma release assays of anti-mycobacterial immunity. Recent work has observed high heritability of these immune assays indicating the critical role of the host genetic background on the establishment of infection and latency. Additional genetic studies have identified the host genetic background as an important covariate for the proper interpretation of the results obtained from LTBI assays. Taken together, these data suggest TB surveillance and control can likely be improved by including host genetic information into the interpretation of these widely used assays.

  7. Host genetics and parasitic infections.

    PubMed

    Mangano, V D; Modiano, D

    2014-12-01

    Parasites still impose a high death and disability burden on human populations, and are therefore likely to act as selective factors for genetic adaptations. Genetic epidemiological investigation of parasitic diseases is aimed at disentangling the mechanisms underlying immunity and pathogenesis by looking for associations or linkages between loci and susceptibility phenotypes. Until recently, most studies used a candidate gene approach and were relatively underpowered, with few attempts at replicating findings in different populations. However, in the last 5 years, genome-wide and/or multicentre studies have been conducted for severe malaria, visceral leishmaniasis, and cardiac Chagas disease, providing some novel important insights. Furthermore, studies of helminth infections have repeatedly shown the involvement of common loci in regulating susceptibility to distinct diseases such as schistosomiasis, ascariasis, trichuriasis, and onchocherciasis. As more studies are conducted, evidence is increasing that at least some of the identified susceptibility loci are shared not only among parasitic diseases but also with immunological disorders such as allergy or autoimmune disease, suggesting that parasites may have played a role in driving the evolution of the immune system. PMID:25273270

  8. Host genetics and parasitic infections.

    PubMed

    Mangano, V D; Modiano, D

    2014-12-01

    Parasites still impose a high death and disability burden on human populations, and are therefore likely to act as selective factors for genetic adaptations. Genetic epidemiological investigation of parasitic diseases is aimed at disentangling the mechanisms underlying immunity and pathogenesis by looking for associations or linkages between loci and susceptibility phenotypes. Until recently, most studies used a candidate gene approach and were relatively underpowered, with few attempts at replicating findings in different populations. However, in the last 5 years, genome-wide and/or multicentre studies have been conducted for severe malaria, visceral leishmaniasis, and cardiac Chagas disease, providing some novel important insights. Furthermore, studies of helminth infections have repeatedly shown the involvement of common loci in regulating susceptibility to distinct diseases such as schistosomiasis, ascariasis, trichuriasis, and onchocherciasis. As more studies are conducted, evidence is increasing that at least some of the identified susceptibility loci are shared not only among parasitic diseases but also with immunological disorders such as allergy or autoimmune disease, suggesting that parasites may have played a role in driving the evolution of the immune system.

  9. Dysregulation of Toll-Like Receptor 7 Compromises Innate and Adaptive T Cell Responses and Host Resistance to an Attenuated West Nile Virus Infection in Old Mice

    PubMed Central

    Xie, Guorui; Luo, Huanle; Pang, Lan; Peng, Bi-hung; Winkelmann, Evandro; McGruder, Brenna; Hesse, Joseph; Whiteman, Melissa; Campbell, Gerald; Milligan, Gregg N.; Cong, Yingzi; Barrett, Alan D.

    2015-01-01

    ABSTRACT The elderly are known to have enhanced susceptibility to infections and an impaired capacity to respond to vaccination. West Nile virus (WNV), a mosquito-borne flavivirus, has induced severe neurological symptoms, mostly in the elderly population. No vaccines are available for human use. Recent work showed that an attenuated WNV, a nonstructural (NS) 4B-P38G mutant, induced no lethality but strong immune responses in young (6- to 10-week-old) mice. While studying protective efficacy, we found unexpectedly that old (21- to 22-month) mice were susceptible to WNV NS4B-P38G mutant infection but were protected from subsequent lethal wild-type WNV challenge. Compared to responses in young mice, the NS4B-P38G mutant triggered higher inflammatory cytokine and interleukin-10 (IL-10) production, a delayed γδ T cell expansion, and lower antibody and WNV-specific T cell responses in old mice. Toll-like receptor 7 (TLR7) is expressed on multiple types of cells. Impaired TLR7 signaling in old mice led to dendritic cell (DC) antigen-presenting function compromise and a reduced γδ T cell and regulatory T cell (Treg) expansion during NS4B-P38G mutant infection. R848, a TLR7 agonist, decreased host vulnerability in NS4B-P38G-infected old mice by enhancing γδ T cell and Treg expansion and the antigen-presenting capacity of DCs, thereby promoting T cell responses. In summary, our results suggest that dysregulation of TLR7 partially contributes to impaired innate and adaptive T cell responses and an enhanced vulnerability in old mice during WNV NS4B-P38G mutant infection. R848 increases the safety and efficacy during immunization of old mice with the WNV NS4B-P38G mutant. IMPORTANCE The elderly are known to have enhanced susceptibility to infections and an impaired capacity to respond to vaccination. West Nile virus (WNV), an emerging mosquito-borne flavivirus, has induced severe neurological symptoms more frequently in the elderly population. No vaccines are available

  10. Blood Groups in Infection and Host Susceptibility

    PubMed Central

    2015-01-01

    SUMMARY Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome. PMID:26085552

  11. Relationship between VacA Toxin and Host Cell Autophagy in Helicobacter pylori Infection of the Human Stomach: A Few Answers, Many Questions.

    PubMed

    Ricci, Vittorio

    2016-01-01

    Helicobacter pylori is a Gram-negative bacterium that colonizes the stomach of about half the global population and represents the greatest risk factor for gastric malignancy. The relevance of H. pylori for gastric cancer development is equivalent to that of tobacco smoking for lung cancer. VacA toxin seems to play a pivotal role in the overall strategy of H. pylori towards achieving persistent gastric colonization. This strategy appears to involve the modulation of host cell autophagy. After an overview of autophagy and its role in infection and carcinogenesis, I critically review current knowledge about the action of VacA on host cell autophagy during H. pylori infection of the human stomach. Although VacA is a key player in modulation of H. pylori-induced autophagy, a few discrepancies in the data are also evident and many questions remain to be answered. We are thus still far from a definitive understanding of the molecular mechanisms through which VacA affects autophagy and the consequences of this toxin action on the overall pathogenic activity of H. pylori. PMID:27376331

  12. Relationship between VacA Toxin and Host Cell Autophagy in Helicobacter pylori Infection of the Human Stomach: A Few Answers, Many Questions

    PubMed Central

    Ricci, Vittorio

    2016-01-01

    Helicobacter pylori is a Gram-negative bacterium that colonizes the stomach of about half the global population and represents the greatest risk factor for gastric malignancy. The relevance of H. pylori for gastric cancer development is equivalent to that of tobacco smoking for lung cancer. VacA toxin seems to play a pivotal role in the overall strategy of H. pylori towards achieving persistent gastric colonization. This strategy appears to involve the modulation of host cell autophagy. After an overview of autophagy and its role in infection and carcinogenesis, I critically review current knowledge about the action of VacA on host cell autophagy during H. pylori infection of the human stomach. Although VacA is a key player in modulation of H. pylori-induced autophagy, a few discrepancies in the data are also evident and many questions remain to be answered. We are thus still far from a definitive understanding of the molecular mechanisms through which VacA affects autophagy and the consequences of this toxin action on the overall pathogenic activity of H. pylori. PMID:27376331

  13. Visualizing viral transport and host infection

    NASA Astrophysics Data System (ADS)

    Son, Kwangmin; Guasto, Jeffrey; Cubillos-Ruiz, Andres; Sullivan, Matthew; Stocker, Roman; MIT Team

    2013-11-01

    A virus is a non-motile infectious agent that can only replicate inside a living host. They consist of a <100 nm diameter capsid which houses their DNA, and a <20 nm diameter tail used to inject DNA to the host, which are classified into three different morphologies by the tail type: short tail (~ 10 nm, podovirus), rigid contractile tail (~ 100 nm, myovirus), or flexible noncontractile tail (~ 300 nm, siphovirus). Combining microfluidics with epifluorescent microscopy, we studied the simultaneous diffusive transport governing the initial encounter and ultimately the infection of a non-motile cyanobacteria host (~ 1 μm prochlorococcus) and their viral (phage) counterparts in real time. This methodology allows us to quantify the virus-host encounter/adsorption dynamics and subsequently the effectiveness of various tail morphologies for viral infection. Viral transport and the role of viral morphology in host-virus interactions are critical to our understanding of both ecosystem dynamics and human health, as well as to the evolution of virus morphology.

  14. Distinct temporal changes in host cell lncRNA expression during the course of an adenovirus infection.

    PubMed

    Zhao, Hongxing; Chen, Maoshan; Lind, Sara Bergström; Pettersson, Ulf

    2016-05-01

    The deregulation of cellular long non-coding RNA (lncRNA) expression during a human adenovirus infection was studied by deep sequencing. Expression of lncRNAs increased substantially following the progression of the infection. Among 645 significantly expressed lncRNAs, the expression of 398 was changed more than 2-fold. More than 80% of them were up-regulated and 80% of them were detected during the late phase. Based on the genomic locations of the deregulated lncRNAs in relation to known mRNAs and miRNAs, they were predicted to be involved in growth, structure, apoptosis and wound healing in the early phase, cell proliferation in the intermediate phase and protein synthesis, modification and transport in the late phase. The most significant functions of cellular RNA-binding proteins, previously shown to interact with the deregulated lncRNAs identified here, are involved in RNA splicing, nuclear export and translation events. We hypothesize that adenoviruses exploit the lncRNA network to optimize their reproduction. PMID:27003248

  15. Identification of host response signatures of infection.

    SciTech Connect

    Branda, Steven S.; Sinha, Anupama; Bent, Zachary

    2013-02-01

    Biological weapons of mass destruction and emerging infectious diseases represent a serious and growing threat to our national security. Effective response to a bioattack or disease outbreak critically depends upon efficient and reliable distinguishing between infected vs healthy individuals, to enable rational use of scarce, invasive, and/or costly countermeasures (diagnostics, therapies, quarantine). Screening based on direct detection of the causative pathogen can be problematic, because culture- and probe-based assays are confounded by unanticipated pathogens (e.g., deeply diverged, engineered), and readily-accessible specimens (e.g., blood) often contain little or no pathogen, particularly at pre-symptomatic stages of disease. Thus, in addition to the pathogen itself, one would like to detect infection-specific host response signatures in the specimen, preferably ones comprised of nucleic acids (NA), which can be recovered and amplified from tiny specimens (e.g., fingerstick draws). Proof-of-concept studies have not been definitive, however, largely due to use of sub-optimal sample preparation and detection technologies. For purposes of pathogen detection, Sandia has developed novel molecular biology methods that enable selective isolation of NA unique to, or shared between, complex samples, followed by identification and quantitation via Second Generation Sequencing (SGS). The central hypothesis of the current study is that variations on this approach will support efficient identification and verification of NA-based host response signatures of infectious disease. To test this hypothesis, we re-engineered Sandia's sophisticated sample preparation pipelines, and developed new SGS data analysis tools and strategies, in order to pioneer use of SGS for identification of host NA correlating with infection. Proof-of-concept studies were carried out using specimens drawn from pathogen-infected non-human primates (NHP). This work provides a strong foundation for

  16. [Host defense mechanisms against Salmonella infection].

    PubMed

    Mizuno, Yumi

    2004-12-01

    Salmonella is one of the gram negative intracellular pathogens. The immune response to Salmonella includes innate immunity and adaptive immunity. The intestinal epithelium, neutrophil, macrophage, dendritic cell, NK cell, NK T cell and gammadelta T cell take important part in former process, and antigen specific T cell and B cell take part in the later process. Macrophages and dendritic cells increase in number early after Salmonella infection and produce variety of cytokines. Especially, IL-12, IL-15 and IL-18 play important roles in protection against Salmonella infection, proliferation of NK cell, NKT cell and gammadelta T cell, producing IFN-gamma, in addition, IL-12 and IL-18 induce IFN-gamma production by Th1 cells and adaptive immune response.

  17. TGF-β receptor type II costameric localization in cardiomyocytes and host cell TGF-β response is disrupted by Trypanosoma cruzi infection.

    PubMed

    Calvet, Claudia Magalhães; Silva, Tatiana Araújo; DE Melo, Tatiana Galvão; DE Araújo-Jorge, Tânia Cremonini; Pereira, Mirian Claudia DE Souza

    2016-05-01

    Transforming growth factor beta (TGF-β) cytokine is involved in Chagas disease establishment and progression. Since Trypanosoma cruzi can modulate host cell receptors, we analysed the TGF-β receptor type II (TβRII) expression and distribution during T. cruzi - cardiomyocyte interaction. TβRII immunofluorescent staining revealed a striated organization in cardiomyocytes, which was co-localized with vinculin costameres and enhanced (38%) after TGF-β treatment. Cytochalasin D induced a decrease of 45·3% in the ratio of cardiomyocytes presenting TβRII striations, demonstrating an association of TβRII with the cytoskeleton. Western blot analysis showed that cytochalasin D significantly inhibited Smad 2 phosphorylation and fibronectin stimulation after TGF-β treatment in cardiomyocytes. Trypanosoma cruzi infection elicited a decrease of 79·8% in the frequency of cardiomyocytes presenting TβRII striations, but did not interfere significantly in its expression. In addition, T. cruzi-infected cardiomyocytes present a lower response to exogenous TGF-β, showing no enhancement of TβRII striations and a reduction of phosphorylated Smad 2, with no significant difference in TβRII expression when compared to uninfected cells. Together, these results suggest that the co-localization of TβRII with costameres is important in activating the TGF-β signalling cascade, and that T. cruzi-derived cytoskeleton disorganization could result in altered or low TGF-β response in infected cardiomyocytes.

  18. Intracellular demonstration of active TGFbeta1 in B cells and plasma cells of autoimmune mice. IgG-bound TGFbeta1 suppresses neutrophil function and host defense against Staphylococcus aureus infection.

    PubMed Central

    Caver, T E; O'Sullivan, F X; Gold, L I; Gresham, H D

    1996-01-01

    Infection remains a leading cause of morbidity and mortality in patients with SLE. To investigate this, previously we assessed the host defense status of autoimmune MRL/lpr mice and found that elaboration of active TGFbeta suppressed neutrophil function and decreased survival in response to Staphylococcus aureus infection. The purpose of the present work was to elucidate the molecular form and the cellular source of the active TGFbeta involved. Here, we report for the first time that TGFbeta1 is found in the active form inside B cells and plasma cells and that it circulates in the plasma complexed with IgG in two murine models of systemic autoimmunity and in some patients with SLE. IgG-bound active TGFbeta1 is many times more potent than uncomplexed active TGFbeta1 for suppression of neutrophil function in vitro and host defense against S. aureus infection in vivo. These data indicate that TGFbeta1 is in the active form inside B cells and plasma cells, that the formation of a complex of IgG and active TGFbeta1 is greatly accelerated in autoimmunity, and that this complex is extremely potent for suppression of PMN function and host defense against bacterial infection. PMID:8958212

  19. Defective interfering influenza viruses and host cells: establishment and maintenance of persistent influenza virus infection in MDBK and HeLa cells.

    PubMed

    De, B K; Nayak, D P

    1980-12-01

    WSN (H0N1) influenza virus upon undiluted passages in different species of cells, namely, bovine kidney (MDBK), chicken embryo (CEF), and HeLa cells, produced a varying amount of defective interfering (DI) virus which correlated well with the ability of the species of cell to produce infectious virus. However, the nature of the influenza DI viral RNA produced from a single clonal stock was essentially identical in all three cells types, suggesting that these cells do not exert a great selective pressure in the amplification of specific DI viral RNAs either at early or late passages. DI viruses produced from one subtype (H0N1) could interfere with the replication of infectious viruses belonging to other subtypes (H1N1, H3N2). DI viral RNAs could also replicate with the helper function of other subtype viruses. The persistent infection of MDBK and HeLa cells could be initiated by coinfecting cells with both temperature-sensitive mutants (ts-) and DI influenza viruses. Persistently infected cultures cultures at early passages (up to passage 7) showed a cyclical pattern of cell lysis and virus production (crisis), whereas, at later passages (after passage 20), they produced little or no virus and were resistant to infection by homologous virus but not by heterologous virus. The majority of persistently infected cells, however, contained the complete viral genome since they expressed viral antigens and produced infectious centers. Selection of a slow-growing temperature-sensitive variant rather than the presence of DI virus or interferon appears to be critical in maintaining persistent influenza infection in these cells.

  20. Leishmania Infection Engages Non-Receptor Protein Kinases Differentially to Persist in Infected Hosts

    PubMed Central

    Zhang, Naixin; Kima, Peter E.

    2016-01-01

    Protein kinases play important roles in the regulation of cellular activities. In cells infected by pathogens, there is an increasing appreciation that dysregulated expression of protein kinases promotes the success of intracellular infections. In Leishmania-infected cells, expression and activation of protein kinases, such as the mitogen-activated protein kinases, kinases in the PI3-kinase signaling pathway, and kinases in the NF-κB-signaling pathway, are modulated in some manner. Several recent reviews have discussed our current understanding of the roles of these kinases in Leishmania infections. Apart from the kinases in the pathways enumerated above, there are other host cell protein kinases that are activated during the Leishmania infection of mammalian cells whose roles also appear to be significant. This review discusses recent observations on the Abl family of protein kinases and the protein kinase regulated by RNA in Leishmania infections. PMID:27148265

  1. Leishmania Infection Engages Non-Receptor Protein Kinases Differentially to Persist in Infected Hosts.

    PubMed

    Zhang, Naixin; Kima, Peter E

    2016-01-01

    Protein kinases play important roles in the regulation of cellular activities. In cells infected by pathogens, there is an increasing appreciation that dysregulated expression of protein kinases promotes the success of intracellular infections. In Leishmania-infected cells, expression and activation of protein kinases, such as the mitogen-activated protein kinases, kinases in the PI3-kinase signaling pathway, and kinases in the NF-κB-signaling pathway, are modulated in some manner. Several recent reviews have discussed our current understanding of the roles of these kinases in Leishmania infections. Apart from the kinases in the pathways enumerated above, there are other host cell protein kinases that are activated during the Leishmania infection of mammalian cells whose roles also appear to be significant. This review discusses recent observations on the Abl family of protein kinases and the protein kinase regulated by RNA in Leishmania infections.

  2. Ultrastructural and cytochemical studies on the infection of wheat spikes byFusarium culmorum as well as on degradation of cell wall components and localization of mycotoxins in the host tissue.

    PubMed

    Kang, Z; Buchenauer, H

    2000-03-01

    The infection process and pathway of spreading ofFusarium culmorum in wheat spikes was examined by means of light, scanning and transmission electron microscopy after spray inoculation and single spikelet inoculation. Macroconidia of the pathogen germinated on the host surfaces, however, hyphal development and penetration of host tissues normally occurred on the inner surfaces of the lemma, glume and palea as well as on the ovary. The pathogen spread downward to the rachilla and rachis node by inter- and intracellular growth from the glume, lemma, palea and ovary. The pathogen extended in the rachis in upward and downward direction by inter- and intracellular growth inside and outside of the vascular bundles of the rachis. The spreading of the hyphae in the host tissues was associated with pronounced alterations including disintegration and digestion of host cell walls, suggesting production of cell wall degrading enzymes during infection and spreading in the host tissues. Immunogold labelling studies revealed that accumulation ofFusarium toxins in infected wheat spike tissue showed a close relationship to pathological changes in the host cells, symptom appearance and pathogen colonisation of the host tissue.Fusarium toxins may play an important role in wheat head blight development.

  3. Discovery of host-viral protein complexes during infection

    PubMed Central

    Rowles, Daniell L.; Terhune, Scott S.; Cristea, Ileana M.

    2014-01-01

    Summary Viruses have co-evolved with their hosts, developing effective approaches for hijacking and manipulating host cellular processes. Therefore, for their efficient replication and spread, viruses depend on dynamic and temporally-regulated interactions with host proteins. The rapid identification of host proteins targeted by viral proteins during infection provides significant insights into mechanisms of viral protein function. The resulting discoveries often lead to unique and innovative hypotheses on viral protein function. Here, we describe a robust method for identifying virus-host protein interactions and protein complexes, which we have successfully utilized to characterize spatial-temporal protein interactions during infections with either DNA or RNA viruses, including human cytomegalovirus (HCMV), herpes simplex virus type 1 (HSV-1), pseudorabies virus (PRV), human immunodeficiency virus (HIV-1), Sindbis, and West Nile virus (WNV). This approach involves cryogenic cell lysis, rapid immunoaffinity purification targeting a virus or host protein, followed by identification of associated proteins using mass spectrometry. Like most proteomic approaches, this methodology has evolved over the past few years and continues to evolve. We are presenting here the updated approaches for each step, and discuss alternative strategies allowing for the protocol to be optimized for different biological systems. PMID:23996249

  4. Chlamydia Infection Across Host Species Boundaries Promotes Distinct Sets of Transcribed Anti-Apoptotic Factors.

    PubMed

    Messinger, Joshua E; Nelton, Emmalin; Feeney, Colleen; Gondek, David C

    2015-01-01

    Chlamydiae, obligate intracellular bacteria, cause significant human and veterinary associated diseases. Having emerged an estimated 700-million years ago, these bacteria have twice adapted to humans as a host species, causing sexually transmitted infection (C. trachomatis) and respiratory associated disease (C. pneumoniae). The principle mechanism of host cell defense against these intracellular bacteria is the induction of cell death via apoptosis. However, in the "arms race" of co-evolution, Chlamydiae have developed mechanisms to promote cell viability and inhibit cell death. Herein we examine the impact of Chlamydiae infection across multiple host species on transcription of anti-apoptotic genes. We found mostly distinct patterns of gene expression (Mcl1 and cIAPs) elicited by each pathogen-host pair indicating Chlamydiae infection across host species boundaries does not induce a universally shared host response. Understanding species specific host-pathogen interactions is paramount to deciphering how potential pathogens become emerging diseases. PMID:26779446

  5. Chlamydia Infection Across Host Species Boundaries Promotes Distinct Sets of Transcribed Anti-Apoptotic Factors

    PubMed Central

    Messinger, Joshua E.; Nelton, Emmalin; Feeney, Colleen; Gondek, David C.

    2015-01-01

    Chlamydiae, obligate intracellular bacteria, cause significant human and veterinary associated diseases. Having emerged an estimated 700-million years ago, these bacteria have twice adapted to humans as a host species, causing sexually transmitted infection (C. trachomatis) and respiratory associated disease (C. pneumoniae). The principle mechanism of host cell defense against these intracellular bacteria is the induction of cell death via apoptosis. However, in the “arms race” of co-evolution, Chlamydiae have developed mechanisms to promote cell viability and inhibit cell death. Herein we examine the impact of Chlamydiae infection across multiple host species on transcription of anti-apoptotic genes. We found mostly distinct patterns of gene expression (Mcl1 and cIAPs) elicited by each pathogen-host pair indicating Chlamydiae infection across host species boundaries does not induce a universally shared host response. Understanding species specific host-pathogen interactions is paramount to deciphering how potential pathogens become emerging diseases. PMID:26779446

  6. Schistosome Infection Stimulates Host CD4+ T Helper Cell and B-Cell Responses against a Novel Egg Antigen, Thioredoxin Peroxidase

    PubMed Central

    Williams, David L.; Asahi, Hiroko; Botkin, Douglas J.; Stadecker, Miguel J.

    2001-01-01

    Egg granuloma formation during schistosome infections is mediated by CD4+ T helper (Th) cells sensitized to egg antigens; however, most of the relevant sensitizing egg antigens are still unknown. Here we show that schistosome thioredoxin peroxidase (TPx)-1 is a novel T- and B-cell egg antigen in schistosome-infected mice. CD4+ Th cell responses to fractionated egg components identified a significant response against a 26-kDa antigen; a partial amino acid sequence of this antigen was found to be identical to that of Schistosoma mansoni TPx-1. The native TPx-1 elicited significant proliferative responses as well as gamma interferon (IFN-γ), interleukin-2 (IL-2), IL-4, and IL-5 secretion in CD4+ cells from 8.5-week-infected CBA and C57BL/6 mice. By comparison, recombinant TPx-1 elicited a smaller, more type 1-polarized response, with significant production of IFN-γ and IL-2, less IL-5, and essentially no IL-4. In C57BL/6 mice the responses to TPx-1 were relatively more prominent than that directed against the major egg antigen, Sm-p40, whereas in CBA mice the reverse was true. B-cell responses were also monitored in infected C57BL/6, C3H, CBA, and BALB/c mice. All strains had significant antibody levels against the TPx-1 protein, but the most significant antibody production ensued following parasite oviposition. TPx-1 was localized in eggs and shown to be secreted by eggs. The identification of egg antigens is important to understand the specific basis of granuloma formation in schistosome infections and may prove to be useful in strategies to ameliorate pathological responses. PMID:11160011

  7. Replication of Ljungan virus in cell culture: the genomic 5'-end, infectious cDNA clones and host cell response to viral infections.

    PubMed

    Ekström, Jens-Ola; Tolf, Conny; Fahlgren, Camilla; Johansson, E Susanne; Arbrandt, Gustav; Niklasson, Bo; Edman, Kjell-A; Lindberg, A Michael

    2007-12-01

    Ljungan virus (LV) is a picornavirus recently isolated from bank voles (Clethrionomys glareolus). The previously uncharacterised 5'-end sequence of the LV genome was determined. Infectious cDNA clones were constructed of the wild type LV prototype strain 87-012 and of the cytolytically replicating cell culture adapted variant 87-012G. Virus generated from cDNA clones showed identical growth characteristics as uncloned virus stocks. Cell culture adapted LV, 87-012G, showed a clear cytopathic effect (CPE) at 3-4 days post-infection (p.i.). Virus titers, determined by plaque titration, increased however only within the first 18h p.i. Replication of LV (+) strand RNA was determined by real-time PCR and corresponded in time with increasing titers. In contrast, the amounts of the replication intermediate, the (-) strand, continued to increase until the cells showed CPE. This indicates separate controlling mechanisms for replication of LV (+) and (-) genome strands. Replication was also monitored by immunofluorescence (IF) staining. IF staining of both prototype 87-012 and the CPE causing 87-012G showed groups of 5-25 infected cells at 48h p.i., suggesting a, for picornaviruses, not previously described direct cell-to-cell transmission.

  8. The Host Specificities of Baculovirus per os Infectivity Factors.

    PubMed

    Song, Jingjiao; Wang, Xi; Hou, Dianhai; Huang, Huachao; Liu, Xijia; Deng, Fei; Wang, Hualin; Arif, Basil M; Hu, Zhihong; Wang, Manli

    2016-01-01

    Baculoviruses are insect-specific pathogens with a generally narrow host ranges. Successful primary infection is initiated by the proper interaction of at least 8 conserved per os infectivity factors (PIFs) with the host's midgut cells, a process that remains largely a mystery. In this study, we investigated the host specificities of the four core components of the PIF complex, P74, PIF1, PIF2 and PIF3 by using Helicoverpa armigera nucleopolyhedrovirus (HearNPV) backbone. The four pifs of HearNPV were replaced by their counterparts from a group I Autographa californica multiple nucleopolyhedrovirus (AcMNPV) or a group II Spodoptera litura nucleopolyhedrovirus (SpltNPV). Transfection and infection assays showed that all the recombinant viruses were able to produce infectious budded viruses (BVs) and were lethal to H. armigera larvae via intrahaemocoelic injection. However, feeding experiments using very high concentration of occlusion bodies demonstrated that all the recombinant viruses completely lost oral infectivity except SpltNPV pif3 substituted pif3-null HearNPV (vHaBacΔpif3-Sppif3-ph). Furthermore, bioassay result showed that the median lethal concentration (LC50) value of vHaBacΔpif3-Sppif3-ph was 23-fold higher than that of the control virus vHaBacΔpif3-Hapif3-ph, indicating that SpltNPV pif3 can only partially substitute the function of HearNPV pif3. These results suggested that most of PIFs tested have strict host specificities, which may account, at least in part, for the limited host ranges of baculoviruses. PMID:27454435

  9. Control of Host Cell Phosphorylation by Legionella Pneumophila

    PubMed Central

    Haenssler, Eva; Isberg, Ralph R.

    2011-01-01

    Phosphorylation is one of the most frequent modifications in intracellular signaling and is implicated in many processes ranging from transcriptional control to signal transduction in innate immunity. Many pathogens modulate host cell phosphorylation pathways to promote growth and establish an infectious disease. The intracellular pathogen Legionella pneumophila targets and exploits the host phosphorylation system throughout the infection cycle as part of its strategy to establish an environment beneficial for replication. Key to this manipulation is the L. pneumophila Icm/Dot type IV secretion system, which translocates bacterial proteins into the host cytosol that can act directly on phosphorylation cascades. This review will focus on the different stages of L. pneumophila infection, in which host kinases and phosphatases contribute to infection of the host cell and promote intracellular survival of the pathogen. This includes the involvement of phosphatidylinositol 3-kinases during phagocytosis as well as the role of phosphoinositide metabolism during the establishment of the replication vacuole. Furthermore, L. pneumophila infection modulates the NF-κB and mitogen-activated protein kinase pathways, two signaling pathways that are central to the host innate immune response and involved in regulation of host cell survival. Therefore, L. pneumophila infection manipulates host cell signal transduction by phosphorylation at multiple levels. PMID:21747787

  10. Type I interferons increase host susceptibility to Trypanosoma cruzi infection.

    PubMed

    Chessler, Anne-Danielle C; Caradonna, Kacey L; Da'dara, Akram; Burleigh, Barbara A

    2011-05-01

    Trypanosoma cruzi, the protozoan parasite that causes human Chagas' disease, induces a type I interferon (IFN) (IFN-α/β) response during acute experimental infection in mice and in isolated primary cell types. To examine the potential impact of the type I IFN response in shaping outcomes in experimental T. cruzi infection, groups of wild-type (WT) and type I IFN receptor-deficient (IFNAR(-/-)) 129sv/ev mice were infected with two different T. cruzi strains under lethal and sublethal conditions and several parameters were measured during the acute stage of infection. The results demonstrate that type I IFNs are not required for early host protection against T. cruzi. In contrast, under conditions of lethal T. cruzi challenge, WT mice succumbed to infection whereas IFNAR(-/-) mice were ultimately able to control parasite growth and survive. T. cruzi clearance in and survival of IFNAR(-/-) mice were accompanied by higher levels of IFN-γ production by isolated splenocytes in response to parasite antigen. The suppression of IFN-γ in splenocytes from WT mice was independent of IL-10 levels. While the impact of type I IFNs on the production of IFN-γ and other cytokines/chemokines remains to be fully determined in the context of T. cruzi infection, our data suggest that, under conditions of high parasite burden, type I IFNs negatively impact IFN-γ production, initiating a detrimental cycle that contributes to the ultimate failure to control infection. These findings are consistent with a growing theme in the microbial pathogenesis field in which type I IFNs can be detrimental to the host in a variety of nonviral pathogen infection models. PMID:21402764

  11. The Host Specificities of Baculovirus per os Infectivity Factors

    PubMed Central

    Song, Jingjiao; Wang, Xi; Hou, Dianhai; Huang, Huachao; Liu, Xijia; Deng, Fei; Wang, Hualin; Arif, Basil M.; Hu, Zhihong; Wang, Manli

    2016-01-01

    Baculoviruses are insect-specific pathogens with a generally narrow host ranges. Successful primary infection is initiated by the proper interaction of at least 8 conserved per os infectivity factors (PIFs) with the host’s midgut cells, a process that remains largely a mystery. In this study, we investigated the host specificities of the four core components of the PIF complex, P74, PIF1, PIF2 and PIF3 by using Helicoverpa armigera nucleopolyhedrovirus (HearNPV) backbone. The four pifs of HearNPV were replaced by their counterparts from a group I Autographa californica multiple nucleopolyhedrovirus (AcMNPV) or a group II Spodoptera litura nucleopolyhedrovirus (SpltNPV). Transfection and infection assays showed that all the recombinant viruses were able to produce infectious budded viruses (BVs) and were lethal to H. armigera larvae via intrahaemocoelic injection. However, feeding experiments using very high concentration of occlusion bodies demonstrated that all the recombinant viruses completely lost oral infectivity except SpltNPV pif3 substituted pif3-null HearNPV (vHaBacΔpif3-Sppif3-ph). Furthermore, bioassay result showed that the median lethal concentration (LC50) value of vHaBacΔpif3-Sppif3-ph was 23-fold higher than that of the control virus vHaBacΔpif3-Hapif3-ph, indicating that SpltNPV pif3 can only partially substitute the function of HearNPV pif3. These results suggested that most of PIFs tested have strict host specificities, which may account, at least in part, for the limited host ranges of baculoviruses. PMID:27454435

  12. Within-Host Spatiotemporal Dynamics of Plant Virus Infection at the Cellular Level

    PubMed Central

    Lafforgue, Guillaume; Elena, Santiago F.

    2014-01-01

    A multicellular organism is not a monolayer of cells in a flask; it is a complex, spatially structured environment, offering both challenges and opportunities for viruses to thrive. Whereas virus infection dynamics at the host and within-cell levels have been documented, the intermediate between-cell level remains poorly understood. Here, we used flow cytometry to measure the infection status of thousands of individual cells in virus-infected plants. This approach allowed us to determine accurately the number of cells infected by two virus variants in the same host, over space and time as the virus colonizes the host. We found a low overall frequency of cellular infection (<0.3), and few cells were coinfected by both virus variants (<0.1). We then estimated the cellular contagion rate (R), the number of secondary infections per infected cell per day. R ranged from 2.43 to values not significantly different from zero, and generally decreased over time. Estimates of the cellular multiplicity of infection (MOI), the number of virions infecting a cell, were low (<1.5). Variance of virus-genotype frequencies increased strongly from leaf to cell levels, in agreement with a low MOI. Finally, there were leaf-dependent differences in the ease with which a leaf could be colonized, and the number of virions effectively colonizing a leaf. The modeling of infection patterns suggests that the aggregation of virus-infected cells plays a key role in limiting spread; matching the observation that cell-to-cell movement of plant viruses can result in patches of infection. Our results show that virus expansion at the between-cell level is restricted, probably due to the host environment and virus infection itself. PMID:24586207

  13. Interaction of chlamydiae and host cells in vitro.

    PubMed Central

    Moulder, J W

    1991-01-01

    The obligately intracellular bacteria of the genus Chlamydia, which is only remotely related to other eubacterial genera, cause many diseases of humans, nonhuman mammals, and birds. Interaction of chlamydiae with host cells in vitro has been studied as a model of infection in natural hosts and as an example of the adaptation of an organism to an unusual environment, the inside of another living cell. Among the novel adaptations made by chlamydiae have been the substitution of disulfide-bond-cross-linked polypeptides for peptidoglycans and the use of host-generated nucleotide triphosphates as sources of metabolic energy. The effect of contact between chlamydiae and host cells in culture varies from no effect at all to rapid destruction of either chlamydiae or host cells. When successful infection occurs, it is usually followed by production of large numbers of progeny and destruction of host cells. However, host cells containing chlamydiae sometimes continue to divide, with or without overt signs of infection, and chlamydiae may persist indefinitely in cell cultures. Some of the many factors that influence the outcome of chlamydia-host cell interaction are kind of chlamydiae, kind of host cells, mode of chlamydial entry, nutritional adequacy of the culture medium, presence of antimicrobial agents, and presence of immune cells and soluble immune factors. General characteristics of chlamydial multiplication in cells of their natural hosts are reproduced in established cell lines, but reproduction in vitro of the subtle differences in chlamydial behavior responsible for the individuality of the different chlamydial diseases will require better in vitro models. PMID:2030670

  14. Sterol Carrier Protein 2, a Critical Host Factor for Dengue Virus Infection, Alters the Cholesterol Distribution in Mosquito Aag2 Cells.

    PubMed

    Fu, Qiang; Inankur, Bahar; Yin, John; Striker, Rob; Lan, Que

    2015-09-01

    Host factors that enable dengue virus (DENV) to propagate in the mosquito host cells are unclear. It is known that cellular cholesterol plays an important role in the life cycle of DENV in human host cells but unknown if the lipid requirements differ for mosquito versus mammalian. In mosquito Aedes aegypti, sterol carrier protein 2 (SCP-2) is critical for cellular cholesterol homeostasis. In this study, we identified SCP-2 as a critical host factor for DENV production in mosquito Aag2 cells. Treatment with a small molecule commonly referred to as SCPI-1, (N-(4-{[4-(3,4-dichlorophenyl)-1,3-thiazol-2-yl]amino}phenyl)acetamide hydrobromide, a known inhibitor of SCP-2, or knockdown of SCP-2 dramatically repressed the virus production in mosquito but not mammalian cells. We showed that the intracellular cholesterol distribution in mosquito cells was altered by SCP-2 inhibitor treatment, suggesting that SCP-2-mediated cholesterol trafficking pathway is important for DENV viral production. A comparison of the effect of SCP-2 on mosquito and human cells suggests that SCPI-1 treatment decreases cholesterol in both cell lines, but this decrease in cholesterol only leads to a decline in viral titer in mosquito host cells, perhaps, owing to a more drastic effect on perinuclear cholesterol storages in mosquito cells that was absent in human cells. SCP-2 had no inhibitory effect on another enveloped RNA virus grown in mosquito cells, suggesting that SCP-2 does not have a generalized anti-cellular or antiviral effect. Our cell culture results imply that SCP-2 may play a limiting role in mosquito-dengue vector competence.

  15. Mechanisms of host cell invasion by Trypanosoma cruzi.

    PubMed

    Caradonna, Kacey L; Burleigh, Barbara A

    2011-01-01

    One of the more accepted concepts in our understanding of the biology of early Trypanosoma cruzi-host cell interactions is that the mammalian-infective trypomastigote forms of the parasite must transit the host cell lysosomal compartment in order to establish a productive intracellular infection. The acidic environment of the lysosome provides the appropriate conditions for parasite-mediated disruption of the parasitophorous vacuole and release of T. cruzi into the host cell cytosol, where replication of intracellular amastigotes occurs. Recent findings indicate a level of redundancy in the lysosome-targeting process where T. cruzi trypomastigotes exploit different cellular pathways to access host cell lysosomes in non-professional phagocytic cells. In addition, the reversible nature of the host cell penetration process was recently demonstrated when conditions for fusion of the nascent parasite vacuole with the host endosomal-lysosomal system were not met. Thus, the concept of parasite retention as a critical component of the T. cruzi invasion process was introduced. Although it is clear that host cell recognition, attachment and signalling are required to initiate invasion, integration of this knowledge with our understanding of the different routes of parasite entry is largely lacking. In this chapter, we focus on current knowledge of the cellular pathways exploited by T. cruzi trypomastigotes to invade non-professional phagocytic cells and to gain access to the host cell lysosome compartment. PMID:21884886

  16. Severe hindrance of viral infection propagation in spatially extended hosts.

    PubMed

    Capitán, José A; Cuesta, José A; Manrubia, Susanna C; Aguirre, Jacobo

    2011-01-01

    The production of large progeny numbers affected by high mutation rates is a ubiquitous strategy of viruses, as it promotes quick adaptation and survival to changing environments. However, this situation often ushers in an arms race between the virus and the host cells. In this paper we investigate in depth a model for the dynamics of a phenotypically heterogeneous population of viruses whose propagation is limited to two-dimensional geometries, and where host cells are able to develop defenses against infection. Our analytical and numerical analyses are developed in close connection to directed percolation models. In fact, we show that making the space explicit in the model, which in turn amounts to reducing viral mobility and hindering the infective ability of the virus, connects our work with similar dynamical models that lie in the universality class of directed percolation. In addition, we use the fact that our model is a multicomponent generalization of the Domany-Kinzel probabilistic cellular automaton to employ several techniques developed in the past in that context, such as the two-site approximation to the extinction transition line. Our aim is to better understand propagation of viral infections with mobility restrictions, e.g., in crops or in plant leaves, in order to inspire new strategies for effective viral control.

  17. The ecology of host immune responses to chronic avian haemosporidian infection.

    PubMed

    Ellis, Vincenzo A; Kunkel, Melanie R; Ricklefs, Robert E

    2014-11-01

    Host responses to parasitism in the wild are often studied in the context of single host-parasite systems, which provide little insight into the ecological dynamics of host-parasite interactions within a community. Here we characterized immune system responses to mostly low-intensity, chronic infection by haemosporidian parasites in a sample of 424 individuals of 22 avian host species from the same local assemblage in the Missouri Ozarks. Two types of white blood cells (heterophils and lymphocytes) were elevated in infected individuals across species, as was the acute-phase protein haptoglobin, which is associated with inflammatory immune responses. Linear discriminant analysis indicated that individuals infected by haemosporidians occupied a subset of the overall white blood cell multivariate space that was also occupied by uninfected individuals, suggesting that these latter individuals might have harbored other pathogens or that parasites more readily infect individuals with a specific white blood cell profile. DNA sequence-defined lineages of haemosporidian parasites were sparsely distributed across the assemblage of hosts. In one well-sampled host species, the red-eyed vireo (Vireo olivaceus), heterophils were significantly elevated in individuals infected with one but not another of two common parasite lineages. Another well-sampled host, the yellow-breasted chat (Icteria virens), exhibited no differences in immune response to different haemosporidian lineages. Our results indicate that while immune responses to infection may be generalized across host species, parasite-specific immune responses may also occur. PMID:25179282

  18. Cellular transcriptional profiling in influenza A virus-infected lung epithelial cells: The role of the nonstructural NS1 protein in the evasion of the host innate defense and its potential contribution to pandemic influenza

    NASA Astrophysics Data System (ADS)

    Geiss, Gary K.; Salvatore, Mirella; Tumpey, Terrence M.; Carter, Victoria S.; Wang, Xiuyan; Basler, Christopher F.; Taubenberger, Jeffery K.; Bumgarner, Roger E.; Palese, Peter; Katze, Michael G.; García-Sastre, Adolfo

    2002-08-01

    The NS1 protein of influenza A virus contributes to viral pathogenesis, primarily by enabling the virus to disarm the host cell type IFN defense system. We examined the downstream effects of NS1 protein expression during influenza A virus infection on global cellular mRNA levels by measuring expression of over 13,000 cellular genes in response to infection with wild-type and mutant viruses in human lung epithelial cells. Influenza A/PR/8/34 virus infection resulted in a significant induction of genes involved in the IFN pathway. Deletion of the viral NS1 gene increased the number and magnitude of expression of cellular genes implicated in the IFN, NF-B, and other antiviral pathways. Interestingly, different IFN-induced genes showed different sensitivities to NS1-mediated inhibition of their expression. A recombinant virus with a C-terminal deletion in its NS1 gene induced an intermediate cellular mRNA expression pattern between wild-type and NS1 knockout viruses. Most significantly, a virus containing the 1918 pandemic NS1 gene was more efficient at blocking the expression of IFN-regulated genes than its parental influenza A/WSN/33 virus. Taken together, our results suggest that the cellular response to influenza A virus infection in human lung cells is significantly influenced by the sequence of the NS1 gene, demonstrating the importance of the NS1 protein in regulating the host cell response triggered by virus infection.

  19. Host-to-host variation of ecological interactions in polymicrobial infections

    PubMed Central

    Mukherjee, Sayak; Weimer, Kristin E.; Seok, Sang-Cheol; Ray, Will C.; Jayaprakash, C.; Vieland, Veronica J.; Swords, W. Edward

    2014-01-01

    Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a Maximum Entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species. PMID:25473880

  20. Host-to-host variation of ecological interactions in polymicrobial infections

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sayak; Weimer, Kristin E.; Seok, Sang-Cheol; Ray, Will C.; Jayaprakash, C.; Vieland, Veronica J.; Swords, W. Edward; Das, Jayajit

    2015-02-01

    Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

  1. Host-to-host variation of ecological interactions in polymicrobial infections.

    PubMed

    Mukherjee, Sayak; Weimer, Kristin E; Seok, Sang-Cheol; Ray, Will C; Jayaprakash, C; Vieland, Veronica J; Swords, W Edward; Das, Jayajit

    2014-01-01

    Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species. PMID:25473880

  2. Modified host cells with efflux pumps

    DOEpatents

    Dunlop, Mary J.; Keasling, Jay D.; Mukhopadhyay, Aindrila

    2016-08-30

    The present invention provides for a modified host cell comprising a heterologous expression of an efflux pump capable of transporting an organic molecule out of the host cell wherein the organic molecule at a sufficiently high concentration reduces the growth rate of or is lethal to the host cell.

  3. The Type III Secretion Translocation Pore Senses Host Cell Contact

    PubMed Central

    Armentrout, Erin I.; Rietsch, Arne

    2016-01-01

    Type III secretion systems (T3SS) are nano-syringes used by a wide range of Gram-negative pathogens to promote infection by directly injecting effector proteins into targeted host cells. Translocation of effectors is triggered by host-cell contact and requires assembly of a pore in the host-cell plasma membrane, which consists of two translocator proteins. Our understanding of the translocation pore, how it is assembled in the host cell membrane and its precise role in effector translocation, is extremely limited. Here we use a genetic technique to identify protein-protein contacts between pore-forming translocator proteins, as well as the T3SS needle-tip, that are critical for translocon function. The data help establish the orientation of the translocator proteins in the host cell membrane. Analysis of translocon function in mutants that break these contacts demonstrates that an interaction between the pore-forming translocator PopD and the needle-tip is required for sensing host cell contact. Moreover, tethering PopD at a dimer interface also specifically prevents host-cell sensing, arguing that the translocation pore is actively involved in detecting host cell contact. The work presented here therefore establishes a signal transduction pathway for sensing host cell contact that is initiated by a conformational change in the translocation pore, and is subsequently transmitted to the base of the apparatus via a specific contact between the pore and the T3SS needle-tip. PMID:27022930

  4. siRNA Screening Identifies the Host Hexokinase 2 (HK2) Gene as an Important Hypoxia-Inducible Transcription Factor 1 (HIF-1) Target Gene in Toxoplasma gondii-Infected Cells

    PubMed Central

    Menendez, Matthew T.; Teygong, Crystal; Wade, Kristin; Florimond, Celia

    2015-01-01

    ABSTRACT Although it is established that oxygen availability regulates cellular metabolism and growth, little is known regarding how intracellular pathogens use host factors to grow at physiological oxygen levels. Therefore, large-scale human small interfering RNA screening was performed to identify host genes important for growth of the intracellular protozoan parasite Toxoplasma gondii at tissue oxygen tensions. Among the genes identified by this screen, we focused on the hexokinase 2 (HK2) gene because its expression is regulated by hypoxia-inducible transcription factor 1 (HIF-1), which is important for Toxoplasma growth. Toxoplasma increases host HK2 transcript and protein levels in a HIF-1-dependent manner. In addition, parasite growth at 3% oxygen is restored in HIF-1-deficient cells transfected with HK2 expression plasmids. Both HIF-1 activation and HK2 expression were accompanied by increases in host glycolytic flux, suggesting that enhanced HK2 expression in parasite-infected cells is functionally significant. Parasite dependence on host HK2 and HIF-1 expression is not restricted to transformed cell lines, as both are required for parasite growth in nontransformed C2C12 myoblasts and HK2 is upregulated in vivo following infection. While HK2 is normally associated with the cytoplasmic face of the outer mitochondrial membrane at physiological O2 levels, HK2 relocalizes to the host cytoplasm following infection, a process that is required for parasite growth at 3% oxygen. Taken together, our findings show that HIF-1-dependent expression and relocalization of HK2 represent a novel mechanism by which Toxoplasma establishes its replicative niche at tissue oxygen tensions. PMID:26106078

  5. Selection and refinement: the malaria parasite's infection and exploitation of host hepatocytes.

    PubMed

    Kaushansky, Alexis; Kappe, Stefan Hi

    2015-08-01

    Plasmodium parasites belong to the Apicomplexan phylum, which consists mostly of obligate intracellular pathogens that vary dramatically in host cell tropism. Plasmodium sporozoites are highly hepatophilic. The specific molecular mechanisms, which facilitate sporozoite selection and successful infection of hepatocytes, remain poorly defined. Here, we discuss the parasite and host factors which are critical to hepatocyte infection. We derive a model where sporozoites initially select host cells that constitute a permissive environment and then further refine the chosen hepatocyte during liver stage development, ensuring life cycle progression. While many unknowns of pre-erythrocytic infection remain, advancing models and technologies that enable analysis of human malaria parasites and of single infected cells will catalyze a comprehensive understanding of the interaction between the malaria parasite and its hepatocyte host. PMID:26102161

  6. Host social behavior and parasitic infection: A multifactorial approach

    USGS Publications Warehouse

    Ezenwa, V.O.

    2004-01-01

    I examined associations between several components of host social organization, including group size and gregariousness, group stability, territoriality and social class, and gastrointestinal parasite load in African bovids. At an intraspecific level, group size was positively correlated with parasite prevalence, but only when the parasite was relatively host specific and only among host species living in stable groups. Social class was also an important predictor of infection rates. Among gazelles, territorial males had higher parasite intensities than did either bachelor males or females and juveniles, suggesting that highly territorial individuals may be either more exposed or more susceptible to parasites. Associations among territoriality, grouping, and parasitism were also found across taxa. Territorial host genera were more likely to be infected with strongyle nematodes than were nonterritorial hosts, and gregarious hosts were more infected than were solitary hosts. Analyses also revealed that gregariousness and territoriality had an interactive effect on individual parasite richness, whereby hosts with both traits harbored significantly more parasite groups than did hosts with only one or neither trait. Overall, study results indicate that multiple features of host social behavior influence infection risk and suggest that synergism between traits also has important effects on host parasite load.

  7. Recombinant sialidase NanA (rNanA) cleaves α2-3 linked sialic acid of host cell surface N-linked glycoprotein to promote Edwardsiella tarda infection.

    PubMed

    Chigwechokha, Petros Kingstone; Tabata, Mutsumi; Shinyoshi, Sayaka; Oishi, Kazuki; Araki, Kyosuke; Komatsu, Masaharu; Itakura, Takao; Shiozaki, Kazuhiro

    2015-11-01

    Edwardsiella tarda is one of the major pathogenic bacteria affecting both marine and freshwater fish species. Sialidase NanA expressed endogenously in E. tarda is glycosidase removing sialic acids from glycoconjugates. Recently, the relationship of NanA sialidase activity to E. tarda infection has been reported, however, the mechanism with which sialidase NanA aids the pathogenicity of E. tarda remained unclear. Here, we comprehensively determined the biochemical properties of NanA towards various substrates in vitro to provide novel insights on the potential NanA target molecule at the host cell. GAKS cell pretreated with recombinant NanA showed increased susceptibility to E. tarda infection. Moreover, sialidase inhibitor treated E. tarda showed a significantly reduced ability to infect GAKS cells. These results indicate that NanA-induced desialylation of cell surface glycoconjugates is essential for the initial step of E. tarda infection. Among the natural substrates, NanA exhibited the highest activity towards 3-sialyllactose, α2-3 linked sialic acid carrying sialoglycoconjugates. Supporting this finding, intact GAKS cell membrane exposed to recombinant NanA showed changes of glycoconjugates only in α2-3 sialo-linked glycoproteins, but not in glycolipids and α2-6 sialo-linked glycoproteins. Lectin staining of cell surface glycoprotein provided further evidence that α2-3 sialo-linkage of the N-linked glycoproteins was the most plausible target of NanA sialidase. To confirm the significance of α2-3 sialo-linkage desialylation for E. tarda infection, HeLa cells which possessed lower amount of α2-3 sialo-linkage glycoprotein were used for infection experiment along with GAKS cells. As a result, infection of HeLa cells by E. tarda was significantly reduced when compared to GAKS cells. Furthermore, E. tarda infection was significantly inhibited by mannose pretreatment suggesting that the bacterium potentially recognizes and binds to mannose or mannose containing

  8. Identification of Toxoplasma gondii Genes Responsive to the Host Immune Response during In Vivo Infection

    PubMed Central

    Skariah, Sini; Mordue, Dana G.

    2012-01-01

    Toxoplasma gondii is an obligate intracellular protozoa parasite that causes the disease toxoplasmosis. It resides within host cells in a parasitophorous vacuole distinct from the host cell endocytic system. T. gondii was used as a model to investigate how obligate intracellular parasites alter their gene expression in response to the host immune response during infection compared to growth in host cells in vitro. While bacterial pathogens clearly alter gene expression to adapt to the host environment during infection, the degree to which the external environment affects gene expression by obligate intracellular pathogens sequestered within host cells is less clear. The global transcriptome of T. gondii was analyzed in vivo in the presence and absence of the IFN-γ-dependent host innate immune response. The parasites' in vivo transcriptome was also compared to its transcriptome in vitro in fibroblast cells. Our results indicate that the parasite transcriptome is significantly altered during in vivo infection in the presence, but not absence, of IFN–γ-dependent immunity compared with fibroblasts infected in vitro. Many of the parasite genes increased in vivo appear to be common to an early general stress response by the parasite; surprisingly putative oocyst stage specific genes were also disproportionately increased during infection. PMID:23071600

  9. Iron Regulatory Proteins Mediate Host Resistance to Salmonella Infection.

    PubMed

    Nairz, Manfred; Ferring-Appel, Dunja; Casarrubea, Daniela; Sonnweber, Thomas; Viatte, Lydie; Schroll, Andrea; Haschka, David; Fang, Ferric C; Hentze, Matthias W; Weiss, Guenter; Galy, Bruno

    2015-08-12

    Macrophages are essential for systemic iron recycling, and also control iron availability to pathogens. Iron metabolism in mammalian cells is orchestrated posttranscriptionally by iron-regulatory proteins (IRP)-1 and -2. Here, we generated mice with selective and combined ablation of both IRPs in macrophages to investigate the role of IRPs in controlling iron availability. These animals are hyperferritinemic but otherwise display normal clinical iron parameters. However, mutant mice rapidly succumb to systemic infection with Salmonella Typhimurium, a pathogenic bacterium that multiplies within macrophages, with increased bacterial burdens in liver and spleen. Ex vivo infection experiments indicate that IRP function restricts bacterial access to iron via the EntC and Feo bacterial iron-acquisition systems. Further, IRPs contain Salmonella by promoting the induction of lipocalin 2, a host antimicrobial factor that inhibits bacterial uptake of iron-laden siderophores, and by suppressing the ferritin iron pool. This work reveals the importance of the IRPs in innate immunity.

  10. IL-17A impairs host tolerance during airway chronic infection by Pseudomonas aeruginosa

    PubMed Central

    Lorè, Nicola Ivan; Cigana, Cristina; Riva, Camilla; De Fino, Ida; Nonis, Alessandro; Spagnuolo, Lorenza; Sipione, Barbara; Cariani, Lisa; Girelli, Daniela; Rossi, Giacomo; Basso, Veronica; Colombo, Carla; Mondino, Anna; Bragonzi, Alessandra

    2016-01-01

    Resistance and tolerance mechanisms participate to the interplay between host and pathogens. IL-17-mediated response has been shown to be crucial for host resistance to respiratory infections, whereas its role in host tolerance during chronic airway colonization is still unclear. Here, we investigated whether IL-17-mediated response modulates mechanisms of host tolerance during airways chronic infection by P. aeruginosa. First, we found that IL-17A levels were sustained in mice at both early and advanced stages of P. aeruginosa chronic infection and confirmed these observations in human respiratory samples from cystic fibrosis patients infected by P. aeruginosa. Using IL-17a−/− or IL-17ra−/− mice, we found that the deficiency of IL-17A/IL-17RA axis was associated with: i) increased incidence of chronic infection and bacterial burden, indicating its role in the host resistance to P. aeruginosa; ii) reduced cytokine levels (KC), tissue innate immune cells and markers of tissue damage (pro-MMP-9, elastin degradation, TGF-β1), proving alteration of host tolerance. Blockade of IL-17A activity by a monoclonal antibody, started when chronic infection is established, did not alter host resistance but increased tolerance. In conclusion, this study identifies IL-17-mediated response as a negative regulator of host tolerance during P. aeruginosa chronic airway infection. PMID:27189736

  11. [How does the apicomplexan parasite Theileria control host cell identity?].

    PubMed

    Marsolier, Justine; Weitzman, Jonathan B

    2014-01-01

    Infectious agents, like bacteria or virus, are responsible for a large number of pathologies in mammals. Microbes have developed mechanisms for interacting with host cell pathways and hijacking cellular machinery to change the phenotypic state. In this review, we focus on an interesting apicomplexan parasite called Theileria. Infection by the tick-transmitted T. annulata parasite causes Tropical Theileriosis in North Africa and Asia, and the related T. parva parasite causes East Coast Fever in Sub-Saharan Africa. This parasite is the only eukaryote known to induce the transformation of its mammalian host cells. Indeed, T. annulata and T. parva infect bovine leukocytes leading to transforming phenotypes, which partially mirror human lymphoma pathologies. Theileria infection causes hyperproliferation, invasiveness and escape from apoptosis, presumably through the manipulation of host cellular pathways. Several host-signaling mechanisms have been implicated. Here we describe the mechanisms involved in parasite-induced transformation phenotypes.

  12. Alterations of host cell ubiquitination machinery by pathogenic bacteria

    PubMed Central

    Alomairi, Jaafar; Bonacci, Thomas; Ghigo, Eric; Soubeyran, Philippe

    2015-01-01

    Response of immune and non-immune cells to pathogens infections is a very dynamic process. It involves the activation/modulation of many pathways leading to actin remodeling, membrane engulfing, phagocytosis, vesicle trafficking, phagolysosome formation, aiming at the destruction of the intruder. These sophisticated and rapid mechanisms rely on post-translational modifications (PTMs) of key host cells' factors, and bacteria have developed various strategies to manipulate them to favor their survival. Among these important PTMs, ubiquitination has emerged as a major mediator/modulator/regulator of host cells response to infections that pathogens have also learned to use for their own benefit. In this mini-review, we summarize our current knowledge about the normal functions of ubiquitination during host cell infection, and we detail its hijacking by model pathogens to escape clearance and to proliferate. PMID:25774357

  13. Strong down-regulation of glycophorin genes: A host defense mechanism against rotavirus infection.

    PubMed

    Salas, Antonio; Marco-Puche, Guillermo; Triviño, Juan Carlos; Gómez-Carballa, Alberto; Cebey-López, Miriam; Rivero-Calle, Irene; Vilanova-Trillo, Lucía; Rodríguez-Tenreiro, Carmen; Gómez-Rial, José; Martinón-Torres, Federico

    2016-10-01

    The mechanisms of rotavirus (RV) infection have been analyzed from different angles but the way in which RV modifies the transcriptome of the host is still unknown. Whole transcriptome shotgun sequencing of peripheral blood samples was used to reveal patterns of expression from the genome of RV-infected patients. RV provokes global changes in the transcriptome of infected cells, involving an over-expression of genes involved in cell cycle and chromatin condensation. While interferon IFI27 was hyper-activated, interferon type II was not suggesting that RV has developed mechanisms to evade the innate response by host cells after virus infection. Most interesting was the inhibition of genes of the glycophorins A and B (GYPA/B) family, which are the major sialoglycoproteins of the human erythrocyte membrane and receptor of several viruses for host invasion. RV infection induces a complex and global response in the host. The strong inhibition of glycophorins suggests a novel defense mechanism of the host to prevent viral infection, inhibiting the expression of receptors used by the virus for infection. The present results add further support to the systemic nature of RV infection.

  14. Strong down-regulation of glycophorin genes: A host defense mechanism against rotavirus infection.

    PubMed

    Salas, Antonio; Marco-Puche, Guillermo; Triviño, Juan Carlos; Gómez-Carballa, Alberto; Cebey-López, Miriam; Rivero-Calle, Irene; Vilanova-Trillo, Lucía; Rodríguez-Tenreiro, Carmen; Gómez-Rial, José; Martinón-Torres, Federico

    2016-10-01

    The mechanisms of rotavirus (RV) infection have been analyzed from different angles but the way in which RV modifies the transcriptome of the host is still unknown. Whole transcriptome shotgun sequencing of peripheral blood samples was used to reveal patterns of expression from the genome of RV-infected patients. RV provokes global changes in the transcriptome of infected cells, involving an over-expression of genes involved in cell cycle and chromatin condensation. While interferon IFI27 was hyper-activated, interferon type II was not suggesting that RV has developed mechanisms to evade the innate response by host cells after virus infection. Most interesting was the inhibition of genes of the glycophorins A and B (GYPA/B) family, which are the major sialoglycoproteins of the human erythrocyte membrane and receptor of several viruses for host invasion. RV infection induces a complex and global response in the host. The strong inhibition of glycophorins suggests a novel defense mechanism of the host to prevent viral infection, inhibiting the expression of receptors used by the virus for infection. The present results add further support to the systemic nature of RV infection. PMID:27491455

  15. Regulation of de novo translation of host cells by manipulation of PERK/PKR and GADD34-PP1 activity during Newcastle disease virus infection.

    PubMed

    Liao, Ying; Gu, Feng; Mao, Xiang; Niu, Qiaona; Wang, Huaxia; Sun, Yingjie; Song, Cuiping; Qiu, Xusheng; Tan, Lei; Ding, Chan

    2016-04-01

    Viral infections result in cellular stress responses, which can trigger protein translation shutoff via phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α). Newcastle disease virus (NDV) causes severe disease in poultry and selectively kills human tumour cells. In this report, we determined that infection of HeLa human cervical cancer cells and DF-1 chicken fibroblast cells with NDV maintained protein at early infection times, 0-12 h post-infection (p.i.), and gradually inhibited global protein translation at late infection times, 12-24 h p.i. Mechanistic studies showed that translation inhibition at late infection times was accompanied by phosphorylation of eIF2α, a checkpoint of translation initiation. Meanwhile, the eIF2α kinase, PKR, was upregulated and activated by phosphorylation and another eIF2α kinase, PERK, was phosphorylated and cleaved into two fragments. Pharmacological inhibition experiments revealed that only PKR activity was required for eIF2α phosphorylation, suggesting that recognition of viral dsRNA by PKR was responsible for translation shutoff. High levels of phospho-eIF2α led to preferential translation of the transcription factor ATF4 and an increase in GADD34 expression. Functionally, GADD34, in conjunction with PP1, dephosphorylated eIF2a and restored protein translation, benefiting virus protein synthesis. However, PP1 was degraded at late infection times, functionally counteracting the upregulation of GADD34. Taken together, our data support that NDV-induced translation shutoff at late infection times was attributed to sustaining phosphorylation of eIF2α, which is mediated by continual activation of PKR and degradation of PP1.

  16. New Role of Nod Proteins in Regulation of Intestinal Goblet Cell Response in the Context of Innate Host Defense in an Enteric Parasite Infection

    PubMed Central

    Wang, Huaqing; Kim, Janice J.; Denou, Emmanuel; Gallagher, Amanda; Thornton, David J.; Shajib, M. Sharif; Xia, Lijun; Schertzer, Jonathan D.; Grencis, Richard K.; Philpott, Dana J.

    2015-01-01

    Mucins secreted by intestinal goblet cells are considered an important component of innate defense in a number of enteric infections, including many parasitic infections, but also likely provide protection against the gut microbiota. Nod proteins are intracellular receptors that play key roles in innate immune response and inflammation. Here, we investigated the role of Nod proteins in regulation of intestinal goblet cell response in naive mice and mice infected with the enteric parasite Trichuris muris. We observed significantly fewer periodic acid-Schiff (PAS)-stained intestinal goblet cells and less mucin (Muc2) in Nod1 and Nod2 double-knockout (Nod DKO) mice after T. muris infection than in wild-type (WT) mice. Expulsion of parasites from the intestine was significantly delayed in Nod DKO mice. Treatment of naive WT mice with Nod1 and Nod2 agonists simultaneously increased numbers of PAS-stained goblet cells and Muc2-expressing cells, whereas treatment with Nod1 or Nod2 separately had no significant effect. Stimulation of mucin-secreting LS174T cells with Nod1 and Nod2 agonists upregulated core 3 β1,3-N-acetylglucosaminyltransferase (C3GnT; an important enzyme in mucin synthesis) and MUC2. We also observed lower numbers of PAS-stained goblet cells and less Muc2 in germfree mice. Treatment with Nod1 and Nod2 agonists enhanced the production of PAS-stained goblet cells and Muc2 in germfree mice. These data provide novel information on the role of Nod proteins in goblet cell response and Muc2 production in relation to intestinal innate defense. PMID:26527214

  17. Mammalian apoptotic signalling pathways: multiple targets of protozoan parasites to activate or deactivate host cell death.

    PubMed

    Graumann, Kristin; Hippe, Diana; Gross, Uwe; Lüder, Carsten G K

    2009-11-01

    Programmed cell death is an essential mechanism of the host to combat infectious agents and to regulate immunity during infection. Consequently, activation and deactivation of the hosts' cell death pathways by protozoan parasites play critical roles in parasite control, pathogenesis, immune evasion and parasite dissemination within the host. Here, we discuss advances in the understanding of these fascinating host-parasite interactions with special emphasis on how protozoa can modulate the cell death apparatus of its host.

  18. Sendai virus utilizes specific sialyloligosaccharides as host cell receptor determinants.

    PubMed Central

    Markwell, M A; Paulson, J C

    1980-01-01

    Purified sialyltransferases (CMP-N-acetyl-neuraminate:D-galactosyl-glycoprotein N-acetylneuraminyl-transferase, EC 2.4.99.1) in conjunction with neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) were used to produce cell surface sialyloligosaccharides of defined sequence to investigate their role in paramyxovirus infection of host cells. Infection of Madin-Darby bovine kidney cells by Sendai virus was monitored by hemagglutination titer of the virus produced and by changes in morphological characteristics. By either criterion, treatment of the cells with Vibrio cholerae neuraminidase to remove cell surface sialic acids rendered them resistant to infection by Sendai virus. Endogenous replacement of receptors by the cell occurred slowly but supported maximal levels of infection within 6 hr. In contrast, sialylation during a 20-min incubation with CMP-sialic acid and beta-galactoside alpha 2,3-sialytransferase restored full susceptibility to infection. This enzyme elaborates the NeuAc alpha 2,3Gal beta 1,3GalNAc (NeuAc, N-acetylneuraminic acid) sequence on glycoproteins and glycolipids. No restoration of infectivity was observed when neuraminidase-treated cells were sialylated by using beta-galactoside alpha 2,6-sialytransferase, which elaborates the NeuAc-alpha 2,6Gal beta 1,4GlcNAc sequence. These results suggest that sialyloligosaccharide receptor determinants of defined sequence are required for Sendai virus infection of host cells. Images PMID:6255459

  19. Host Density and Competency Determine the Effects of Host Diversity on Trematode Parasite Infection

    PubMed Central

    Wojdak, Jeremy M.; Edman, Robert M.; Wyderko, Jennie A.; Zemmer, Sally A.; Belden, Lisa K.

    2014-01-01

    Variation in host species composition can dramatically alter parasite transmission in natural communities. Whether diverse host communities dilute or amplify parasite transmission is thought to depend critically on species traits, particularly on how hosts affect each other’s densities, and their relative competency as hosts. Here we studied a community of potential hosts and/or decoys (i.e. non-competent hosts) for two trematode parasite species, Echinostoma trivolvis and Ribeiroia ondatrae, which commonly infect wildlife across North America. We manipulated the density of a focal host (green frog tadpoles, Rana clamitans), in concert with manipulating the diversity of alternative species, to simulate communities where alternative species either (1) replace the focal host species so that the total number of individuals remains constant (substitution) or (2) add to total host density (addition). For E. trivolvis, we found that total parasite transmission remained roughly equal (or perhaps decreased slightly) when alternative species replaced focal host individuals, but parasite transmission was higher when alternative species were added to a community without replacing focal host individuals. Given the alternative species were roughly equal in competency, these results are consistent with current theory. Remarkably, both total tadpole and per-capita tadpole infection intensity by E. trivolvis increased with increasing intraspecific host density. For R. ondatrae, alternative species did not function as effective decoys or hosts for parasite infective stages, and the diversity and density treatments did not produce clear changes in parasite transmission, although high tank to tank variation in R. ondatrae infection could have obscured patterns. PMID:25119568

  20. Host infection history modifies co-infection success of multiple parasite genotypes.

    PubMed

    Klemme, Ines; Louhi, Katja-Riikka; Karvonen, Anssi

    2016-03-01

    Co-infections by multiple parasite genotypes are common and have important implications for host-parasite ecology and evolution through within-host interactions. Typically, these infections take place sequentially, and therefore, the outcome of co-infection may be shaped by host immune responses triggered by previous infections. For example, in vertebrates, specific immune responses play a central role in protection against disease over the course of life, but co-infection research has mostly focused on previously uninfected individuals. Here, we investigated whether sequential exposure and activation of host resistance in rainbow trout Oncorhynchus mykiss affects infection success and interactions between co-infecting parasite genotypes of the trematode eye-fluke Diplostomum pseudospathaceum. In accordance with earlier results, we show that a simultaneous attack of two parasite genotypes facilitates parasite establishment in previously uninfected hosts. However, we find for the first time that this facilitation in co-infection is lost in hosts with prior infection. We conclude that vertebrate host infection history can affect the direction of within-host-parasite interactions. Our results may have significant implications for the evolution of co-infections and parasite transmission strategies.

  1. Trypanosoma cruzi infection by oral route: how the interplay between parasite and host components modulates infectivity.

    PubMed

    Yoshida, Nobuko

    2008-06-01

    Trypanosoma cruzi infection by oral route constitutes the most important mode of transmission in some geographical regions, as illustrated by reports on microepidemics and outbreaks of acute Chagas' disease acquired by ingestion of food contaminated with parasites from triatomine insects. In the mouse model, T. cruzi metacyclic trypomastigotes invade the gastric mucosal epithelium, a unique portal of entry for systemic infection. High efficiency of metacyclic forms in establishing infection by oral route is associated with expression of gp82, a stage-specific surface molecule that binds to gastric mucin and to epithelial cells. Gp82 promotes parasite entry by triggering the signaling cascades leading to intracellular Ca(2+) mobilization. T. cruzi strains deficient in gp82 can effectively invade cells in vitro, by engaging the Ca(2+) signal-inducing surface glycoprotein gp30. However, they are poorly infective in mice by oral route because gp30 has low affinity for gastric mucin. Metacyclic forms also express gp90, a stage-specific surface glycoprotein that binds to host cells and acts as a negative regulator of invasion. T. cruzi strains expressing gp90 at high levels, in addition to gp82 and gp30, are all poor cell invaders in vitro. Notwithstanding, their infectivity by oral route may vary because, unlike gp82 and gp30, which resist degradation by pepsin in the gastric milieu, the gp90 isoforms of different strains have varying susceptibility to peptic digestion. For instance, in a T. cruzi isolate, derived from an acute case of Chagas' disease acquired by oral route, gp90 is extensively degraded by gastric juice in the mouse stomach and this renders the parasite highly invasive towards target cells. If such an exacerbation of infectivity occurs in humans, it may be responsible for the severity of the disease reported in outbreaks of oral infection.

  2. Shigella flexneri Infection in Caenorhabditis elegans: Cytopathological Examination and Identification of Host Responses

    PubMed Central

    George, Divya T.; Behm, Carolyn A.; Hall, David H.; Mathesius, Ulrike; Rug, Melanie; Nguyen, Ken C. Q.; Verma, Naresh K.

    2014-01-01

    The Gram-negative bacterium Shigella flexneri is the causative agent of shigellosis, a diarrhoeal disease also known as bacillary dysentery. S. flexneri infects the colonic and rectal epithelia of its primate host and induces a cascade of inflammatory responses that culminates in the destruction of the host intestinal lining. Molecular characterization of host-pathogen interactions in this infection has been challenging due to the host specificity of S. flexneri strains, as it strictly infects humans and non-human primates. Recent studies have shown that S. flexneri infects the soil dwelling nematode Caenorhabditis elegans, however, the interactions between S. flexneri and C. elegans at the cellular level and the cause of nematode death are unknown. Here we attempt to gain insight into the complex host-pathogen interactions between S. flexneri and C. elegans. Using transmission electron microscopy, we show that live S. flexneri cells accumulate in the nematode intestinal lumen, produce outer membrane vesicles and invade nematode intestinal cells. Using two-dimensional differential in-gel electrophoresis we identified host proteins that are differentially expressed in response to S. flexneri infection. Four of the identified genes, aco-1, cct-2, daf-19 and hsp-60, were knocked down using RNAi and ACO-1, CCT-2 and DAF-19, which were identified as up-regulated in response to S. flexneri infection, were found to be involved in the infection process. aco-1 RNAi worms were more resistant to S. flexneri infection, suggesting S. flexneri-mediated disruption of host iron homeostasis. cct-2 and daf-19 RNAi worms were more susceptible to infection, suggesting that these genes are induced as a protective mechanism by C. elegans. These observations further our understanding of the processes involved in S. flexneri infection of C. elegans, which is immensely beneficial to the routine use of this new in vivo model to study S. flexneri pathogenesis. PMID:25187942

  3. Herpesvirus Genome Integration into Telomeric Repeats of Host Cell Chromosomes.

    PubMed

    Osterrieder, Nikolaus; Wallaschek, Nina; Kaufer, Benedikt B

    2014-11-01

    It is well known that numerous viruses integrate their genetic material into host cell chromosomes. Human herpesvirus 6 (HHV-6) and oncogenic Marek's disease virus (MDV) have been shown to integrate their genomes into host telomeres of latently infected cells. This is unusual for herpesviruses as most maintain their genomes as circular episomes during the quiescent stage of infection. The genomic DNA of HHV-6, MDV, and several other herpesviruses harbors telomeric repeats (TMRs) that are identical to host telomere sequences (TTAGGG). At least in the case of MDV, viral TMRs facilitate integration into host telomeres. Integration of HHV-6 occurs not only in lymphocytes but also in the germline of some individuals, allowing vertical virus transmission. Although the molecular mechanism of telomere integration is poorly understood, the presence of TMRs in a number of herpesviruses suggests it is their default program for genome maintenance during latency and also allows efficient reactivation.

  4. Viroporins Customize Host Cells for Efficient Viral Propagation

    PubMed Central

    Giorda, Kristina M.

    2013-01-01

    Viruses are intracellular parasites that must access the host cell machinery to propagate. Viruses hijack the host cell machinery to help with entry, replication, packaging, and release of progeny to infect new cells. To carry out these diverse functions, viruses often transform the cellular environment using viroporins, a growing class of viral-encoded membrane proteins that promote viral proliferation. Viroporins modify the integrity of host membranes, thereby stimulating the maturation of viral infection, and are critical for virus production and dissemination. Significant advances in molecular and cell biological approaches have helped to uncover some of the roles that viroporins serve in the various stages of the viral life cycle. In this study, the ability of viroporins to modify the cellular environment will be discussed, with particular emphasis on their role in the stepwise progression of the viral life cycle. PMID:23945006

  5. Human Intestinal Enteroids: a New Model To Study Human Rotavirus Infection, Host Restriction, and Pathophysiology

    PubMed Central

    Saxena, Kapil; Blutt, Sarah E.; Ettayebi, Khalil; Zeng, Xi-Lei; Broughman, James R.; Crawford, Sue E.; Karandikar, Umesh C.; Sastri, Narayan P.; Conner, Margaret E.; Opekun, Antone R.; Graham, David Y.; Qureshi, Waqar; Sherman, Vadim; Foulke-Abel, Jennifer; In, Julie; Kovbasnjuk, Olga; Zachos, Nicholas C.; Donowitz, Mark

    2015-01-01

    ABSTRACT Human gastrointestinal tract research is limited by the paucity of in vitro intestinal cell models that recapitulate the cellular diversity and complex functions of human physiology and disease pathology. Human intestinal enteroid (HIE) cultures contain multiple intestinal epithelial cell types that comprise the intestinal epithelium (enterocytes and goblet, enteroendocrine, and Paneth cells) and are physiologically active based on responses to agonists. We evaluated these nontransformed, three-dimensional HIE cultures as models for pathogenic infections in the small intestine by examining whether HIEs from different regions of the small intestine from different patients are susceptible to human rotavirus (HRV) infection. Little is known about HRVs, as they generally replicate poorly in transformed cell lines, and host range restriction prevents their replication in many animal models, whereas many animal rotaviruses (ARVs) exhibit a broader host range and replicate in mice. Using HRVs, including the Rotarix RV1 vaccine strain, and ARVs, we evaluated host susceptibility, virus production, and cellular responses of HIEs. HRVs infect at higher rates and grow to higher titers than do ARVs. HRVs infect differentiated enterocytes and enteroendocrine cells, and viroplasms and lipid droplets are induced. Heterogeneity in replication was seen in HIEs from different patients. HRV infection and RV enterotoxin treatment of HIEs caused physiological lumenal expansion detected by time-lapse microscopy, recapitulating one of the hallmarks of rotavirus-induced diarrhea. These results demonstrate that HIEs are a novel pathophysiological model that will allow the study of HRV biology, including host restriction, cell type restriction, and virus-induced fluid secretion. IMPORTANCE Our research establishes HIEs as nontransformed cell culture models to understand human intestinal physiology and pathophysiology and the epithelial response, including host restriction of

  6. New signaling pathways govern the host response to C. albicans infection in various niches.

    PubMed

    Liu, Yaoping; Shetty, Amol C; Schwartz, Jennifer A; Bradford, L Latey; Xu, Wenjie; Phan, Qyunh T; Kumari, Priti; Mahurkar, Anup; Mitchell, Aaron P; Ravel, Jacques; Fraser, Claire M; Filler, Scott G; Bruno, Vincent M

    2015-05-01

    Candida albicans, the major invasive fungal pathogen of humans, can cause both debilitating mucosal infections and fatal invasive infections. Understanding the complex nature of the host-pathogen interaction in each of these contexts is essential to developing desperately needed therapies to treat fungal infections. RNA-seq enables a systems-level understanding of infection by facilitating comprehensive analysis of transcriptomes from multiple species (e.g., host and pathogen) simultaneously. We used RNA-seq to characterize the transcriptomes of both C. albicans and human endothelial cells or oral epithelial cells during in vitro infection. Network analysis of the differentially expressed genes identified the activation of several signaling pathways that have not previously been associated with the host response to fungal pathogens. Using an siRNA knockdown approach, we demonstrate that two of these pathways-platelet-derived growth factor BB (PDGF BB) and neural precursor-cell-expressed developmentally down-regulated protein 9 (NEDD9)-govern the host-pathogen interaction by regulating the uptake of C. albicans by host cells. Using RNA-seq analysis of a mouse model of hematogenously disseminated candidiasis (HDC) and episodes of vulvovaginal candidiasis (VVC) in humans, we found evidence that many of the same signaling pathways are activated during mucosal (VVC) and/or disseminated (HDC) infections in vivo. Our analyses have uncovered several signaling pathways at the interface between C. albicans and host cells in various contexts of infection, and suggest that PDGF BB and NEDD9 play important roles in this interaction. In addition, these data provide a valuable community resource for better understanding host-fungal pathogen interactions.

  7. Transcriptome Responses of the Host Trichoplusia ni to Infection by the Baculovirus Autographa californica Multiple Nucleopolyhedrovirus

    PubMed Central

    Chen, Yun-Ru; Zhong, Silin; Fei, Zhangjun; Gao, Shan; Zhang, Shiying; Li, Zhaofei; Wang, Ping

    2014-01-01

    ABSTRACT Productive infection of Trichoplusia ni cells by the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) leads to expression of ∼156 viral genes and results in dramatic cell remodeling. How the cell transcriptome responds to viral infection was unknown due to the lack of a reference genome and transcriptome for T. ni. We used an ∼60-Gb RNA sequencing (RNA-seq) data set from infected and uninfected T. ni cells to generate and annotate a de novo transcriptome assembly of approximately 70,322 T. ni unigenes (assembled transcripts), representing the 48-h infection cycle. Using differential gene expression analysis, we found that the majority of host transcripts were downregulated after 6 h postinfection (p.i.) and throughout the remainder of the infection. In contrast, 5.7% (4,028) of the T. ni unigenes were upregulated during the early period (0 to 6 h p.i.), followed by a decrease through the remainder of the infection cycle. Also, a small subset of genes related to metabolism and stress response showed a significant elevation of transcript levels at 18 and 24 h p.i. but a decrease thereafter. We also examined the responses of genes belonging to a number of specific pathways of interest, including stress responses, apoptosis, immunity, and protein trafficking. We identified specific pathway members that were upregulated during the early phase of the infection. Combined with the parallel analysis of AcMNPV expression, these results provide both a broad and a detailed view of how baculovirus infection impacts the host cell transcriptome to evade cellular defensive responses, to modify cellular biosynthetic pathways, and to remodel cell structure. IMPORTANCE Baculoviruses are insect-specific DNA viruses that are highly pathogenic to their insect hosts. In addition to their use for biological control of certain insects, baculoviruses also serve as viral vectors for numerous biotechnological applications, such as mammalian cell

  8. The host response and molecular pathogenesis associated with respiratory syncytial virus infection

    PubMed Central

    Oshansky, Christine M; Zhang, Wenliang; Moore, Elizabeth; Tripp, Ralph A

    2009-01-01

    Since the isolation of respiratory syncytial virus (RSV) in 1956, its significance as an important human pathogen in infants, the elderly and the immunocompromised has been established. Many important mechanisms contributing to RSV infection, replication and disease pathogenesis have been uncovered; however, there is still insufficient knowledge in these and related areas, which must be addressed to facilitate the development of safe and effective vaccines and therapeutic treatments. A better understanding of the molecular pathogenesis of RSV infection, particularly the host-cell response and transcription profiles to RSV infection, is required to advance disease intervention strategies. Substantial information is accumulating regarding how RSV proteins modulate molecular signaling and regulation of cytokine and chemokine responses to infection, molecular signals regulating programmed cell death, and innate and adaptive immune responses to infection. This review discusses RSV manipulation of the host response to infection and related disease pathogenesis. PMID:19327115

  9. Within-host viral dynamics of dengue serotype 1 infection.

    PubMed

    Clapham, Hannah E; Tricou, Vianney; Van Vinh Chau, Nguyen; Simmons, Cameron P; Ferguson, Neil M

    2014-07-01

    Dengue, the most common mosquito-borne viral infection of humans, is endemic across much of the world, including much of tropical Asia and is increasing in its geographical range. Here, we present a mathematical model of dengue virus dynamics within infected individuals, detailing the interaction between virus and a simple immune response. We fit this model to measurements of plasma viral titre from cases of primary and secondary DENV 1 infection in Vietnam. We show that variation in model parameters governing the immune response is sufficient to create the observed variation in virus dynamics between individuals. Estimating model parameter values, we find parameter differences between primary and secondary cases consistent with the theory of antibody-dependent enhancement (namely enhanced rates of viral entry to target cells in secondary cases). Finally, we use our model to examine the potential impact of an antiviral drug on the within-host dynamics of dengue. We conclude that the impact of antiviral therapy on virus dynamics is likely to be limited if therapy is only started at the onset of symptoms, owing to the typically late stage of viral pathogenesis reached by the time symptoms are manifested and thus treatment is started.

  10. A genomics approach to understanding host response during dengue infection.

    PubMed

    Hibberd, Martin L; Ling, Ling; Tolfvenstam, Thomas; Mitchell, Wayne; Wong, Chris; Kuznetsov, Vladimir A; George, Joshy; Ong, Swee-Hoe; Ruan, Yijun; Wei, Chia L; Gu, Feng; Fink, Joshua; Yip, Andy; Liu, Wei; Schreiber, Mark; Vasudevan, Subhash G

    2006-01-01

    Dengue infection results in a wide clinical spectrum, ranging from asymptomatic, through fever (DF), to the life threatening complications haemorrhagic fever (DHF) and shock syndrome (DSS). Although we now understand that factors such as repeat infections and the type or magnitude of the host response are important in determining severity, the mechanisms of these actions remain largely unknown. Understanding this host-pathogen interaction may enable outcome prediction and new therapy options. Developments in biology now allow a 'systems approach' to be applied to this problem, utilizing whole genomes of both human and virus, in vitro and in vivo to enable a more complete picture of their interplay to be built up. We have developed a chip-based approach to viral sequencing, to increase efficiency and enable large numbers ofgenomes to be completed, together with a web-based interpretation tool. We have also applied human whole genome expression arrays (24000 genes) to characterize the types of host response made to infection and plan to investigate the role of host variation using human whole genome genetic association studies in the future. These technologies have identified novel host pathways involved in viral replication in vitro, and also host immune responses, such as the interferon signalling pathway, that are influenced by viral sequence. This data will be further refined through interlinking with similar data obtained from a large study of dengue patients, initiated in Singapore, that is able to look at the early host response to infection.

  11. Analysis of Cryptic, Systemic Botrytis Infections in Symptomless Hosts.

    PubMed

    Shaw, Michael W; Emmanuel, Christy J; Emilda, Deni; Terhem, Razak B; Shafia, Aminath; Tsamaidi, Dimitra; Emblow, Mark; van Kan, Jan A L

    2016-01-01

    Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. Botrytis cinerea and Botrytis pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents) when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles.

  12. Analysis of Cryptic, Systemic Botrytis Infections in Symptomless Hosts

    PubMed Central

    Shaw, Michael W.; Emmanuel, Christy J.; Emilda, Deni; Terhem, Razak B.; Shafia, Aminath; Tsamaidi, Dimitra; Emblow, Mark; van Kan, Jan A. L.

    2016-01-01

    Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. Botrytis cinerea and Botrytis pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents) when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles. PMID:27242829

  13. Pathogenesis, tissue distribution and host response to Rhabdochlamydia porcellionis infection in rough woodlouse Porcellio scaber.

    PubMed

    Kostanjšek, Rok; Pirc Marolt, Tinkara

    2015-02-01

    Rhabdochlamydia porcellionis is a known intracellular pathogen in digestive glands of the terrestrial isopod crustacean Porcellio scaber. To describe the pathogenesis, tissue distribution and host response to R. porcellionis, we conducted microscopic observations and localization of infection in tissues by Fluorescent In Situ Hybridization (FISH). Digestive glands were confirmed as the primary site of infection. From there, R. porcellionis disseminates either through the apical membrane of infected cells into the lumen of digestive glands and further throughout the digestive tract or into the surrounding hemocoel by rupture of the basal membrane and lamina of infected digestive gland cells. Once in the hemocoel, R. porcellionis infects hindgut cells, hemocytes and hemopoetic tissues while the ventral nerve cord and gonads seem to be devoid of infection despite the presence of rhabdochlamydia on the surface of these organs. The host response to R. porcellionis includes aggregation of hemocytes around the infected cells and formation of multilayered melanized nodules exhibiting endogenous fluorescence. The structure of nodules is asymmetric when hemocytes are deposited on the basal side of infected gut and digestive glands cells, or symmetric, when nodules entrapping clusters of rhabdochlamydiae are deposited on other organs in the hemocoel. The study also revealed a high prevalence of infection in P. scaber populations (up to 27%) and confirmed its detrimental effect on the host. Although agility, behavior and molting cycle of infected animals appear unaffected, in the later stages R. porcellionis infection manifests as severe damage to the digestive system and decreased feeding, which eventually lead to the death of the host organism.

  14. The tail-associated depolymerase of Erwinia amylovora phage L1 mediates host cell adsorption and enzymatic capsule removal, which can enhance infection by other phage.

    PubMed

    Born, Yannick; Fieseler, Lars; Klumpp, Jochen; Eugster, Marcel R; Zurfluh, Katrin; Duffy, Brion; Loessner, Martin J

    2014-07-01

    The depolymerase enzyme (DpoL1) encoded by the T7-like phage L1 efficiently degrades amylovoran, an important virulence factor and major component of the extracellular polysaccharide (EPS) of its host, the plant pathogen Erwinia amylovora. Mass spectrometry analysis of hydrolysed EPS revealed that DpoL1 cleaves the galactose-containing backbone of amylovoran. The enzyme is most active at pH 6 and 50°C, and features a modular architecture. Removal of 180 N-terminal amino acids was shown not to affect enzyme activity. The C-terminus harbours the hydrolase activity, while the N-terminal domain links the enzyme to the phage particle. Electron microscopy demonstrated that DpoL1-specific antibodies cross-link phage particles at their tails, either lateral or frontal, and immunogold staining confirmed that DpoL1 is located at the tail spikes. Exposure of high-level EPS-producing Er. amylovora strain CFBP1430 to recombinant DpoL1 dramatically increased sensitivity to the Dpo-negative phage Y2, which was not the case for EPS-negative mutants or low-level EPS-producing Er. amylovora. Our findings indicate that enhanced phage susceptibility is based on enzymatic removal of the EPS capsule, normally a physical barrier to Y2 infection, and that use of DpoL1 together with the broad host range, virulent phage Y2 represents an attractive combination for biocontrol of fire blight.

  15. Fungal endophyte infection of ryegrass reprograms host metabolism and alters development.

    PubMed

    Dupont, Pierre-Yves; Eaton, Carla J; Wargent, Jason J; Fechtner, Susanne; Solomon, Peter; Schmid, Jan; Day, Robert C; Scott, Barry; Cox, Murray P

    2015-12-01

    Beneficial associations between plants and microbes play an important role in both natural and agricultural ecosystems. For example, associations between fungi of the genus Epichloë, and cool-season grasses are known for their ability to increase resistance to insect pests, fungal pathogens and drought. However, little is known about the molecular changes induced by endophyte infection. To study the impact of endophyte infection, we compared the expression profiles, based on RNA sequencing, of perennial ryegrass infected with Epichloë festucae with noninfected plants. We show that infection causes dramatic changes in the expression of over one third of host genes. This is in stark contrast to mycorrhizal associations, where substantially fewer changes in host gene expression are observed, and is more similar to pathogenic interactions. We reveal that endophyte infection triggers reprogramming of host metabolism, favouring secondary metabolism at a cost to primary metabolism. Infection also induces changes in host development, particularly trichome formation and cell wall biogenesis. Importantly, this work sheds light on the mechanisms underlying enhanced resistance to drought and super-infection by fungal pathogens provided by fungal endophyte infection. Finally, our study reveals that not all beneficial plant-microbe associations behave the same in terms of their effects on the host. PMID:26305687

  16. Norovirus Infection: Replication, Manipulation of Host, and Interaction with the Host Immune Response.

    PubMed

    Sarvestani, Soroush T; Cotton, Ben; Fritzlar, Svenja; O'Donnell, Tanya B; Mackenzie, Jason M

    2016-04-01

    Noroviruses (NoVs) belong to the Caliciviridae family of viruses and are responsible for causing the majority of gastroenteritis outbreaks worldwide. In the past decade, research on NoV biology has intensified because of the discovery of murine NoV and subsequently the first cell culture system and small animal model for NoV replication and pathogenesis. In this review, we discuss the current literature on NoV biology, focusing particularly on NoV replication and the interaction between NoV and the host immune response. Understanding the NoV replication cycle and its interaction with cellular processes and innate immune immunity will help develop molecular targets to control human NoV infection and prevent outbreaks. In addition to the innate immune response, we have documented the current efforts to develop NoV vaccines to control outbreaks. PMID:27046239

  17. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

    PubMed

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-03-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  18. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis

    PubMed Central

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C.; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-01-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  19. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

    PubMed

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-03-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  20. Nucleofection of DCs to Generate Multivirus-specific T Cells for Prevention or Treatment of Viral Infections in the Immunocompromised Host

    PubMed Central

    Gerdemann, Ulrike; Christin, Anne S; Vera, Juan F; Ramos, Carlos A; Fujita, Yuriko; Liu, Hao; Dilloo, Dagmar; Heslop, Helen E; Brenner, Malcolm K; Rooney, Cliona M; Leen, Ann M

    2009-01-01

    Viral infections cause morbidity and mortality in allogeneic hematopoietic stem cell transplant (HSCT) recipients. To prevent and treat these, we have produced and infused cytotoxic T lymphocytes (CTLs) with specificity for Epstein–Barr virus (EBV), cytomegalovirus (CMV), and adenovirus (Adv), and shown that small numbers of infused cells proliferate in vivo and protect against all three viruses. Despite these encouraging results, broader implementation of this approach is limited by the need for infectious virus material (EBV), expensive production of clinical grade adenoviral vectors, and a prolonged (8–12 weeks) period of manufacture. There is also competition between virus-derived antigens within antigen-presenting cells (APCs), limiting extension to additional agents. We now describe an approach that uses DNA nucleofection of dendritic cells (DCs) with DNA plasmids that encode a range of immunodominant and subdominant viral antigens from CMV, EBV, BK, and Adv. Within 10 days, this methodology provides multivirus-reactive CTLs that lack alloreactivity. We further demonstrate that nucleofected DC stimulation can be combined with interferon-γ (IFN-γ) capture technology to produce even more rapid multivirus-CTL products for treatment of acute infection. These CTL generation procedures should increase the feasibility and applicability of T-cell therapy. PMID:19584818

  1. [Up-to-date findings in the host defence mechanism to cryptococcus infection].

    PubMed

    Ishii, Keiko; Kawakami, Kazuyoshi

    2014-01-01

    Cryptococcus neoformans is a medically important opportunistic fungal pathogen with a polysaccharide capsule surrounding the yeast-like cells. In hosts with impaired cell-mediated immunity such as AIDS, uncontrolled infection causes life-threatening meningoencephalitis. In immunocompetent individuals, the host immune response usually limits the growth of the fungal pathogen at the primary infected site, where it may persist, without completely eradicated, in a latent state because of its ability to escape from killing by macrophages. Th1 response in adaptive immunity is essential for the host defense to cryptococcal infection, in which interferon (IFN)-γ polarizes innate macrophages into fungicidal M1 macrophages. Recently, we found that caspase recruitment domain family member (CARD9), an adaptor protein in a signal transduction triggered by C-type lectin receptors, plays a key role in the early production of IFN-γ at the site of infection by recruiting NK cells and CD4(+) and CD8(+) memory-phenotype T cells. We also found that IL-4 produced by Th2 cells stimulates broncoepithelial cells to secrete mucin, which may lead to promotion in the mucociliary clearance of C. neoformans. Here, we summarize the up-to-date findings in the host defense mechanism to this infection with focusing on our recent data.

  2. Mouse cytomegalovirus immediate-early protein 1 binds with host cell repressors to relieve suppressive effects on viral transcription and replication during lytic infection.

    PubMed

    Tang, Qiyi; Maul, Gerd G

    2003-01-01

    Herpesviruses start their transcriptional cascade at nuclear domain 10 (ND10). The deposition of virus genomes at these nuclear sites occurs due to the binding of the interferon-inducible repressor protein promyelocytic leukemia protein (PML) and/or Daxx to a viral DNA-protein complex. However, the presence of repressive proteins at the nuclear site of virus transcription has remained unexplained. We investigated the mouse cytomegalovirus (MCMV) immediate-early 1 protein (IE1), which is necessary for productive infection at low multiplicities of infection and therefore likely to be involved in overcoming cellular repression. Temporal analysis of IE1 distribution revealed its initial segregation into ND10 by binding to PML and/or Daxx and IE1-dependent recruitment of the transcriptional repressor histone deacetylase-2 (HDAC-2) to this site. However, these protein aggregates are dissociated in cells producing sufficient IE1 through titration of PML, Daxx, and HDAC-2. Importantly, binding of IE1 to HDAC-2 decreased deacetylation activity. Moreover, inhibition of HDAC by trichostatin-A resulted in an increase in viral protein synthesis, an increase in cells starting the formation of prereplication compartments, and an increase in the total infectious viruses produced. Thus, IE1, like trichostatin-A, reverses the repressive effect of HDAC evident in the presence of acetylated histones in the immediate-early promoter region. Since HDAC also binds to the promoter region of IE1, as determined by the chromatin immunoprecipitation assay, these combined results suggest that IE1 inhibits or reverses HDAC-mediated repression of the infecting viral genomes, possibly by a process akin to activation of heterochromatin. We propose that even permissive cells can repress transcription of infecting viral genomes through repressors, including HDAC, Daxx, and PML, and the segregation of IE1 to ND10 that would inactivate those repressors. The virus can counter this repression by

  3. Dissection of Francisella-Host Cell Interactions in Dictyostelium discoideum.

    PubMed

    Lampe, Elisabeth O; Brenz, Yannick; Herrmann, Lydia; Repnik, Urska; Griffiths, Gareth; Zingmark, Carl; Sjöstedt, Anders; Winther-Larsen, Hanne C; Hagedorn, Monica

    2016-03-01

    Francisella bacteria cause severe disease in both vertebrates and invertebrates and include one of the most infectious human pathogens. Mammalian cell lines have mainly been used to study the mechanisms by which Francisella manipulates its host to replicate within a large variety of hosts and cell types, including macrophages. Here, we describe the establishment of a genetically and biochemically tractable infection model: the amoeba Dictyostelium discoideum combined with the fish pathogen Francisella noatunensis subsp. noatunensis. Phagocytosed F. noatunensis subsp. noatunensis interacts with the endosomal pathway and escapes further phagosomal maturation by translocating into the host cell cytosol. F. noatunensis subsp. noatunensis lacking IglC, a known virulence determinant required for Francisella intracellular replication, follows the normal phagosomal maturation and does not grow in Dictyostelium. The attenuation of the F. noatunensis subsp. noatunensis ΔiglC mutant was confirmed in a zebrafish embryo model, where growth of F. noatunensis subsp. noatunensis ΔiglC was restricted. In Dictyostelium, F. noatunensis subsp. noatunensis interacts with the autophagic machinery. The intracellular bacteria colocalize with autophagic markers, and when autophagy is impaired (Dictyostelium Δatg1), F. noatunensis subsp. noatunensis accumulates within Dictyostelium cells. Altogether, the Dictyostelium-F. noatunensis subsp. noatunensis infection model recapitulates the course of infection described in other host systems. The genetic and biochemical tractability of the system allows new approaches to elucidate the dynamic interactions between pathogenic Francisella and its host organism. PMID:26712555

  4. Dissection of Francisella-Host Cell Interactions in Dictyostelium discoideum

    PubMed Central

    Lampe, Elisabeth O.; Brenz, Yannick; Herrmann, Lydia; Repnik, Urska; Griffiths, Gareth; Zingmark, Carl; Sjöstedt, Anders; Winther-Larsen, Hanne C.

    2015-01-01

    Francisella bacteria cause severe disease in both vertebrates and invertebrates and include one of the most infectious human pathogens. Mammalian cell lines have mainly been used to study the mechanisms by which Francisella manipulates its host to replicate within a large variety of hosts and cell types, including macrophages. Here, we describe the establishment of a genetically and biochemically tractable infection model: the amoeba Dictyostelium discoideum combined with the fish pathogen Francisella noatunensis subsp. noatunensis. Phagocytosed F. noatunensis subsp. noatunensis interacts with the endosomal pathway and escapes further phagosomal maturation by translocating into the host cell cytosol. F. noatunensis subsp. noatunensis lacking IglC, a known virulence determinant required for Francisella intracellular replication, follows the normal phagosomal maturation and does not grow in Dictyostelium. The attenuation of the F. noatunensis subsp. noatunensis ΔiglC mutant was confirmed in a zebrafish embryo model, where growth of F. noatunensis subsp. noatunensis ΔiglC was restricted. In Dictyostelium, F. noatunensis subsp. noatunensis interacts with the autophagic machinery. The intracellular bacteria colocalize with autophagic markers, and when autophagy is impaired (Dictyostelium Δatg1), F. noatunensis subsp. noatunensis accumulates within Dictyostelium cells. Altogether, the Dictyostelium-F. noatunensis subsp. noatunensis infection model recapitulates the course of infection described in other host systems. The genetic and biochemical tractability of the system allows new approaches to elucidate the dynamic interactions between pathogenic Francisella and its host organism. PMID:26712555

  5. ARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion

    SciTech Connect

    Vieira da Silva, Claudio; Alves da Silva, Erika; Costa Cruz, Mario; Chavrier, Philippe; Arruda Mortara, Renato

    2009-01-16

    Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARF family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RH strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP{sub 2} and PIP{sub 3} to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion.

  6. Structural remodeling of bacteriophage T4 and host membranes during infection initiation

    PubMed Central

    Hu, Bo; Margolin, William; Molineux, Ian J.; Liu, Jun

    2015-01-01

    The first stages of productive bacteriophage infections of bacterial host cells require efficient adsorption to the cell surface followed by ejection of phage DNA into the host cytoplasm. To achieve this goal, a phage virion must undergo significant structural remodeling. For phage T4, the most obvious change is the contraction of its tail. Here, we use skinny E. coli minicells as a host, along with cryo-electron tomography and mutant phage virions, to visualize key structural intermediates during initiation of T4 infection. We show for the first time that most long tail fibers are folded back against the tail sheath until irreversible adsorption, a feature compatible with the virion randomly walking across the cell surface to find an optimal site for infection. Our data confirm that tail contraction is triggered by structural changes in the baseplate, as intermediates were found with remodeled baseplates and extended tails. After contraction, the tail tube penetrates the host cell periplasm, pausing while it degrades the peptidoglycan layer. Penetration into the host cytoplasm is accompanied by a dramatic local outward curvature of the cytoplasmic membrane as it fuses with the phage tail tip. The baseplate hub protein gp27 and/or the ejected tape measure protein gp29 likely form the transmembrane channel for viral DNA passage into the cell cytoplasm. Building on the wealth of prior biochemical and structural information, this work provides new molecular insights into the mechanistic pathway of T4 phage infection. PMID:26283379

  7. Structural remodeling of bacteriophage T4 and host membranes during infection initiation.

    PubMed

    Hu, Bo; Margolin, William; Molineux, Ian J; Liu, Jun

    2015-09-01

    The first stages of productive bacteriophage infections of bacterial host cells require efficient adsorption to the cell surface followed by ejection of phage DNA into the host cytoplasm. To achieve this goal, a phage virion must undergo significant structural remodeling. For phage T4, the most obvious change is the contraction of its tail. Here, we use skinny E. coli minicells as a host, along with cryo-electron tomography and mutant phage virions, to visualize key structural intermediates during initiation of T4 infection. We show for the first time that most long tail fibers are folded back against the tail sheath until irreversible adsorption, a feature compatible with the virion randomly walking across the cell surface to find an optimal site for infection. Our data confirm that tail contraction is triggered by structural changes in the baseplate, as intermediates were found with remodeled baseplates and extended tails. After contraction, the tail tube penetrates the host cell periplasm, pausing while it degrades the peptidoglycan layer. Penetration into the host cytoplasm is accompanied by a dramatic local outward curvature of the cytoplasmic membrane as it fuses with the phage tail tip. The baseplate hub protein gp27 and/or the ejected tape measure protein gp29 likely form the transmembrane channel for viral DNA passage into the cell cytoplasm. Building on the wealth of prior biochemical and structural information, this work provides new molecular insights into the mechanistic pathway of T4 phage infection.

  8. Recombination every day: abundant recombination in a virus during a single multi-cellular host infection.

    PubMed

    Froissart, Remy; Roze, Denis; Uzest, Marilyne; Galibert, Lionel; Blanc, Stephane; Michalakis, Yannis

    2005-03-01

    Viral recombination can dramatically impact evolution and epidemiology. In viruses, the recombination rate depends on the frequency of genetic exchange between different viral genomes within an infected host cell and on the frequency at which such co-infections occur. While the recombination rate has been recently evaluated in experimentally co-infected cell cultures for several viruses, direct quantification at the most biologically significant level, that of a host infection, is still lacking. This study fills this gap using the cauliflower mosaic virus as a model. We distributed four neutral markers along the viral genome, and co-inoculated host plants with marker-containing and wild-type viruses. The frequency of recombinant genomes was evaluated 21 d post-inoculation. On average, over 50% of viral genomes recovered after a single host infection were recombinants, clearly indicating that recombination is very frequent in this virus. Estimates of the recombination rate show that all regions of the genome are equally affected by this process. Assuming that ten viral replication cycles occurred during our experiment-based on data on the timing of coat protein detection-the per base and replication cycle recombination rate was on the order of 2 x 10(-5) to 4 x 10(-5). This first determination of a virus recombination rate during a single multi-cellular host infection indicates that recombination is very frequent in the everyday life of this virus. PMID:15737066

  9. Toxoplasma on the Brain: Understanding Host-Pathogen Interactions in Chronic CNS Infection

    PubMed Central

    Kamerkar, Sushrut; Davis, Paul H.

    2012-01-01

    Toxoplasma gondii is a prevalent obligate intracellular parasite which chronically infects more than a third of the world's population. Key to parasite prevalence is its ability to form chronic and nonimmunogenic bradyzoite cysts, which typically form in the brain and muscle cells of infected mammals, including humans. While acute clinical infection typically involves neurological and/or ocular damage, chronic infection has been more recently linked to behavioral changes. Establishment and maintenance of chronic infection involves a balance between the host immunity and parasite evasion of the immune response. Here, we outline the known cellular interplay between Toxoplasma gondii and cells of the central nervous system and review the reported effects of Toxoplasma gondii on behavior and neurological disease. Finally, we review new technologies which will allow us to more fully understand host-pathogen interactions. PMID:22545203

  10. Mining Host-Pathogen Protein Interactions to Characterize Burkholderia mallei Infectivity Mechanisms

    PubMed Central

    Memišević, Vesna; Zavaljevski, Nela; Rajagopala, Seesandra V.; Kwon, Keehwan; Pieper, Rembert; DeShazer, David; Reifman, Jaques; Wallqvist, Anders

    2015-01-01

    Burkholderia pathogenicity relies on protein virulence factors to control and promote bacterial internalization, survival, and replication within eukaryotic host cells. We recently used yeast two-hybrid (Y2H) screening to identify a small set of novel Burkholderia proteins that were shown to attenuate disease progression in an aerosol infection animal model using the virulent Burkholderia mallei ATCC 23344 strain. Here, we performed an extended analysis of primarily nine B. mallei virulence factors and their interactions with human proteins to map out how the bacteria can influence and alter host processes and pathways. Specifically, we employed topological analyses to assess the connectivity patterns of targeted host proteins, identify modules of pathogen-interacting host proteins linked to processes promoting infectivity, and evaluate the effect of crosstalk among the identified host protein modules. Overall, our analysis showed that the targeted host proteins generally had a large number of interacting partners and interacted with other host proteins that were also targeted by B. mallei proteins. We also introduced a novel Host-Pathogen Interaction Alignment (HPIA) algorithm and used it to explore similarities between host-pathogen interactions of B. mallei, Yersinia pestis, and Salmonella enterica. We inferred putative roles of B. mallei proteins based on the roles of their aligned Y. pestis and S. enterica partners and showed that up to 73% of the predicted roles matched existing annotations. A key insight into Burkholderia pathogenicity derived from these analyses of Y2H host-pathogen interactions is the identification of eukaryotic-specific targeted cellular mechanisms, including the ubiquitination degradation system and the use of the focal adhesion pathway as a fulcrum for transmitting mechanical forces and regulatory signals. This provides the mechanisms to modulate and adapt the host-cell environment for the successful establishment of host infections

  11. Role of sulfated glycans in adherence of the microsporidian Encephalitozoon intestinalis to host cells in vitro.

    PubMed

    Hayman, J Russell; Southern, Timothy R; Nash, Theodore E

    2005-02-01

    Microsporidia are obligate intracellular opportunistic protists that infect a wide variety of animals, including humans, via environmentally resistant spores. Infection requires that spores be in close proximity to host cells so that the hollow polar tube can pierce the cell membrane and inject the spore contents into the cell cytoplasm. Like other eukaryotic microbes, microsporidia may use specific mechanisms for adherence in order to achieve target cell proximity and increase the likelihood of successful infection. Our data show that Encephalitozoon intestinalis exploits sulfated glycans such as the cell surface glycosaminoglycans (GAGs) in selection of and attachment to host cells. When exogenous sulfated glycans are used as inhibitors in spore adherence assays, E. intestinalis spore adherence is reduced by as much as 88%. However, there is no inhibition when nonsulfated glycans are used, suggesting that E. intestinalis spores utilize sulfated host cell glycans in adherence. These studies were confirmed by exposure of host cells to xylopyranoside, which limits host cell surface GAGs, and sodium chlorate, which decreases surface sulfation. Spore adherence studies with CHO mutant cell lines that are deficient in either surface GAGs or surface heparan sulfate also confirmed the necessity of sulfated glycans. Furthermore, when spore adherence is inhibited, host cell infection is reduced, indicating a direct association between spore adherence and infectivity. These data show that E. intestinalis specifically adheres to target cells by way of sulfated host cell surface GAGs and that this mechanism serves to enhance infectivity.

  12. The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection

    PubMed Central

    Pateras, Ioannis S.; Levi, Laura; Mihaljevic, Boris; Rouf, Syed Fazle; Wrande, Marie; Candela, Marco; Turroni, Silvia; Nastasi, Claudia; Consolandi, Clarissa; Peano, Clelia; Tebaldi, Toma; Viero, Gabriella; Gorgoulis, Vassilis G.; Krejsgaard, Thorbjørn; Rhen, Mikael; Frisan, Teresa

    2016-01-01

    Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this issue, we assessed the effects of the Salmonella enterica genotoxin, known as typhoid toxin, in in vivo models of murine infection. Immunocompetent mice were infected with isogenic S. enterica, serovar Typhimurium (S. Typhimurium) strains, encoding either a functional or an inactive typhoid toxin. The presence of the genotoxic subunit was detected 10 days post-infection in the liver of infected mice. Unexpectedly, its expression promoted the survival of the host, and was associated with a significant reduction of severe enteritis in the early phases of infection. Immunohistochemical and transcriptomic analysis confirmed the toxin-mediated suppression of the intestinal inflammatory response. The presence of a functional typhoid toxin further induced an increased frequency of asymptomatic carriers. Our data indicate that the typhoid toxin DNA damaging activity increases host survival and favours long-term colonization, highlighting a complex cross-talk between infection, DNA damage response and host immune response. These findings may contribute to understand why such effectors have been evolutionary conserved and horizontally transferred among Gram-negative bacteria. PMID:27055274

  13. The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection.

    PubMed

    Del Bel Belluz, Lisa; Guidi, Riccardo; Pateras, Ioannis S; Levi, Laura; Mihaljevic, Boris; Rouf, Syed Fazle; Wrande, Marie; Candela, Marco; Turroni, Silvia; Nastasi, Claudia; Consolandi, Clarissa; Peano, Clelia; Tebaldi, Toma; Viero, Gabriella; Gorgoulis, Vassilis G; Krejsgaard, Thorbjørn; Rhen, Mikael; Frisan, Teresa

    2016-04-01

    Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address this issue, we assessed the effects of the Salmonella enterica genotoxin, known as typhoid toxin, in in vivo models of murine infection. Immunocompetent mice were infected with isogenic S. enterica, serovar Typhimurium (S. Typhimurium) strains, encoding either a functional or an inactive typhoid toxin. The presence of the genotoxic subunit was detected 10 days post-infection in the liver of infected mice. Unexpectedly, its expression promoted the survival of the host, and was associated with a significant reduction of severe enteritis in the early phases of infection. Immunohistochemical and transcriptomic analysis confirmed the toxin-mediated suppression of the intestinal inflammatory response. The presence of a functional typhoid toxin further induced an increased frequency of asymptomatic carriers. Our data indicate that the typhoid toxin DNA damaging activity increases host survival and favours long-term colonization, highlighting a complex cross-talk between infection, DNA damage response and host immune response. These findings may contribute to understand why such effectors have been evolutionary conserved and horizontally transferred among Gram-negative bacteria. PMID:27055274

  14. Salmonella Degrades the Host Glycocalyx Leading to Altered Infection and Glycan Remodeling.

    PubMed

    Arabyan, Narine; Park, Dayoung; Foutouhi, Soraya; Weis, Allison M; Huang, Bihua C; Williams, Cynthia C; Desai, Prerak; Shah, Jigna; Jeannotte, Richard; Kong, Nguyet; Lebrilla, Carlito B; Weimer, Bart C

    2016-01-01

    Complex glycans cover the gut epithelial surface to protect the cell from the environment. Invasive pathogens must breach the glycan layer before initiating infection. While glycan degradation is crucial for infection, this process is inadequately understood. Salmonella contains 47 glycosyl hydrolases (GHs) that may degrade the glycan. We hypothesized that keystone genes from the entire GH complement of Salmonella are required to degrade glycans to change infection. This study determined that GHs recognize the terminal monosaccharides (N-acetylneuraminic acid (Neu5Ac), galactose, mannose, and fucose) and significantly (p < 0.05) alter infection. During infection, Salmonella used its two GHs sialidase nanH and amylase malS for internalization by targeting different glycan structures. The host glycans were altered during Salmonella association via the induction of N-glycan biosynthesis pathways leading to modification of host glycans by increasing fucosylation and mannose content, while decreasing sialylation. Gene expression analysis indicated that the host cell responded by regulating more than 50 genes resulting in remodeled glycans in response to Salmonella treatment. This study established the glycan structures on colonic epithelial cells, determined that Salmonella required two keystone GHs for internalization, and left remodeled host glycans as a result of infection. These data indicate that microbial GHs are undiscovered virulence factors. PMID:27389966

  15. Salmonella Degrades the Host Glycocalyx Leading to Altered Infection and Glycan Remodeling

    PubMed Central

    Arabyan, Narine; Park, Dayoung; Foutouhi, Soraya; Weis, Allison M.; Huang, Bihua C.; Williams, Cynthia C.; Desai, Prerak; Shah, Jigna; Jeannotte, Richard; Kong, Nguyet; Lebrilla, Carlito B.; Weimer, Bart C.

    2016-01-01

    Complex glycans cover the gut epithelial surface to protect the cell from the environment. Invasive pathogens must breach the glycan layer before initiating infection. While glycan degradation is crucial for infection, this process is inadequately understood. Salmonella contains 47 glycosyl hydrolases (GHs) that may degrade the glycan. We hypothesized that keystone genes from the entire GH complement of Salmonella are required to degrade glycans to change infection. This study determined that GHs recognize the terminal monosaccharides (N-acetylneuraminic acid (Neu5Ac), galactose, mannose, and fucose) and significantly (p < 0.05) alter infection. During infection, Salmonella used its two GHs sialidase nanH and amylase malS for internalization by targeting different glycan structures. The host glycans were altered during Salmonella association via the induction of N-glycan biosynthesis pathways leading to modification of host glycans by increasing fucosylation and mannose content, while decreasing sialylation. Gene expression analysis indicated that the host cell responded by regulating more than 50 genes resulting in remodeled glycans in response to Salmonella treatment. This study established the glycan structures on colonic epithelial cells, determined that Salmonella required two keystone GHs for internalization, and left remodeled host glycans as a result of infection. These data indicate that microbial GHs are undiscovered virulence factors. PMID:27389966

  16. Molecular anatomy of mouse hepatitis virus persistence: coevolution of increased host cell resistance and virus virulence.

    PubMed Central

    Chen, W; Baric, R S

    1996-01-01

    Persistent infection of murine astrocytoma (DBT) cells with mouse hepatitis virus (MHV) has been established. From this in vitro virus-host system, persistence is mediated at the level of cellular MHV receptor (MHVR) expression and increased virus virulence. MHV persistence selects for resistant host cell populations which abate virus replication. Reductions in MHVR expression were significantly associated with increased host resistance, and transfection of MHVR into resistant host cells completely restored the capacity of cells to support efficient replication of MHV strain A59. The emergence of resistant host cells coselected for variant viruses that had increased avidity for MHVR and also recognized different receptors for entry into resistant cells. These data illustrate that MHV persistence in vitro provides a model to identify critical sites of virus-host interaction at the cellular level which are altered during the evolution of host cell resistance to viral infection and the coevolution of virus virulence. PMID:8648732

  17. Infection, Stem Cells and Cancer Signals

    PubMed Central

    Sell, S.

    2013-01-01

    The association of cancer with preceding parasitic infections has been observed for over 200 years. Some such cancers arise from infection of tissue stem cells by viruses with insertion of viral oncogenes into the host DNA (mouse polyoma virus, mouse mammary tumor virus). In other cases the virus does not insert its DNA into the host cells, but rather commandeers the metabolism of the infected cells, so that the cells continue to proliferate and do not differentiate (human papilloma virus and cervical cancer). Cytoplasmic Epstein Barr virus infection is associated with a specific gene translocation (Ig/c-myc) that activates proliferation of affected cells (Burkitt lymphoma). In chronic osteomyelitis an inflammatory reaction to the infection appears to act through production of inflammatory cytokines and oxygen radical formation to induce epithelial cancers. Infection with Helicobacter pylori leads to epigenetic changes in methylation and infection by a parasite. Clonorchis sinensis also acts as a promoter of cancer of the bile ducts of the liver (cholaniocarcinoma). The common thread among these diverse pathways is that the infections act to alter tissue stem cell signaling with continued proliferation of tumor transit amplifying cells. PMID:21044009

  18. A microfluidic cell-trapping device for single-cell tracking of host-microbe interactions.

    PubMed

    Delincé, Matthieu J; Bureau, Jean-Baptiste; López-Jiménez, Ana Teresa; Cosson, Pierre; Soldati, Thierry; McKinney, John D

    2016-08-16

    The impact of cellular individuality on host-microbe interactions is increasingly appreciated but studying the temporal dynamics of single-cell behavior in this context remains technically challenging. Here we present a microfluidic platform, InfectChip, to trap motile infected cells for high-resolution time-lapse microscopy. This approach allows the direct visualization of all stages of infection, from bacterial uptake to death of the bacterium or host cell, over extended periods of time. We demonstrate the utility of this approach by co-culturing an established host-cell model, Dictyostelium discoideum, with the extracellular pathogen Klebsiella pneumoniae or the intracellular pathogen Mycobacterium marinum. We show that the outcome of such infections is surprisingly heterogeneous, ranging from abortive infection to death of the bacterium or host cell. InfectChip thus provides a simple method to dissect the time-course of host-microbe interactions at the single-cell level, yielding new insights that could not be gleaned from conventional population-based measurements.

  19. Emerging pestiviruses infecting domestic and wildlife hosts.

    PubMed

    Ridpath, Julia F

    2015-06-01

    Until the early 1990 s there were just three recognized species in the pestivirus genus, bovine viral diarrhea virus (BVDV), border disease virus (BDV) and classical swine fever virus (CSFV). Subsequently BVDV were divided into two different species, BVDV1 and BVDV2 and four additional putative pestivirus species have been identified, based on phylogenetic analysis. The four putative pestivirus specices, listed in chronological order of published reports, are Giraffe (isolated from one of several giraffes in the Nanyuki District of Kenya suffering from mucosal disease-like symptoms), HoBi (first isolated from fetal bovine serum originating in Brazil and later from samples originating in Southeast Asia), Pronghorn (isolated from an emaciated blind pronghorn antelope in the USA), and Bungowannah (isolated following an outbreak in pigs, resulting in still birth and neonatal death, in Australia). In addition to the emergence of putative new species of pestivirus, changes in host and virulence of recognized or 'classic' pestiviruses have led to reevaluation of disease control programs and management of domestic and wildlife populations.

  20. Emerging pestiviruses infecting domestic and wildlife hosts.

    PubMed

    Ridpath, Julia F

    2015-06-01

    Until the early 1990 s there were just three recognized species in the pestivirus genus, bovine viral diarrhea virus (BVDV), border disease virus (BDV) and classical swine fever virus (CSFV). Subsequently BVDV were divided into two different species, BVDV1 and BVDV2 and four additional putative pestivirus species have been identified, based on phylogenetic analysis. The four putative pestivirus specices, listed in chronological order of published reports, are Giraffe (isolated from one of several giraffes in the Nanyuki District of Kenya suffering from mucosal disease-like symptoms), HoBi (first isolated from fetal bovine serum originating in Brazil and later from samples originating in Southeast Asia), Pronghorn (isolated from an emaciated blind pronghorn antelope in the USA), and Bungowannah (isolated following an outbreak in pigs, resulting in still birth and neonatal death, in Australia). In addition to the emergence of putative new species of pestivirus, changes in host and virulence of recognized or 'classic' pestiviruses have led to reevaluation of disease control programs and management of domestic and wildlife populations. PMID:26050572

  1. Hijacking Host Cell Highways: Manipulation of the Host Actin Cytoskeleton by Obligate Intracellular Bacterial Pathogens

    PubMed Central

    Colonne, Punsiri M.; Winchell, Caylin G.; Voth, Daniel E.

    2016-01-01

    Intracellular bacterial pathogens replicate within eukaryotic cells and display unique adaptations that support key infection events including invasion, replication, immune evasion, and dissemination. From invasion to dissemination, all stages of the intracellular bacterial life cycle share the same three-dimensional cytosolic space containing the host cytoskeleton. For successful infection and replication, many pathogens hijack the cytoskeleton using effector proteins introduced into the host cytosol by specialized secretion systems. A subset of effectors contains eukaryotic-like motifs that mimic host proteins to exploit signaling and modify specific cytoskeletal components such as actin and microtubules. Cytoskeletal rearrangement promotes numerous events that are beneficial to the pathogen, including internalization of bacteria, structural support for bacteria-containing vacuoles, altered vesicular trafficking, actin-dependent bacterial movement, and pathogen dissemination. This review highlights a diverse group of obligate intracellular bacterial pathogens that manipulate the host cytoskeleton to thrive within eukaryotic cells and discusses underlying molecular mechanisms that promote these dynamic host-pathogen interactions. PMID:27713866

  2. Clustered Intracellular Salmonella enterica Serovar Typhimurium Blocks Host Cell Cytokinesis

    PubMed Central

    Durkin, Charlotte H.; Helaine, Sophie; Boucrot, Emmanuel

    2016-01-01

    Several bacterial pathogens and viruses interfere with the cell cycle of their host cells to enhance virulence. This is especially apparent in bacteria that colonize the gut epithelium, where inhibition of the cell cycle of infected cells enhances the intestinal colonization. We found that intracellular Salmonella enterica serovar Typhimurium induced the binucleation of a large proportion of epithelial cells by 14 h postinvasion and that the effect was dependent on an intact Salmonella pathogenicity island 2 (SPI-2) type 3 secretion system. The SPI-2 effectors SseF and SseG were required to induce binucleation. SseF and SseG are known to maintain microcolonies of Salmonella-containing vacuoles close to the microtubule organizing center of infected epithelial cells. During host cell division, these clustered microcolonies prevented the correct localization of members of the chromosomal passenger complex and mitotic kinesin-like protein 1 and consequently prevented cytokinesis. Tetraploidy, arising from a cytokinesis defect, is known to have a deleterious effect on subsequent cell divisions, resulting in either chromosomal instabilities or cell cycle arrest. In infected mice, proliferation of small intestinal epithelial cells was compromised in an SseF/SseG-dependent manner, suggesting that cytokinesis failure caused by S. Typhimurium delays epithelial cell turnover in the intestine. PMID:27185791

  3. Clustered Intracellular Salmonella enterica Serovar Typhimurium Blocks Host Cell Cytokinesis.

    PubMed

    Santos, António J M; Durkin, Charlotte H; Helaine, Sophie; Boucrot, Emmanuel; Holden, David W

    2016-07-01

    Several bacterial pathogens and viruses interfere with the cell cycle of their host cells to enhance virulence. This is especially apparent in bacteria that colonize the gut epithelium, where inhibition of the cell cycle of infected cells enhances the intestinal colonization. We found that intracellular Salmonella enterica serovar Typhimurium induced the binucleation of a large proportion of epithelial cells by 14 h postinvasion and that the effect was dependent on an intact Salmonella pathogenicity island 2 (SPI-2) type 3 secretion system. The SPI-2 effectors SseF and SseG were required to induce binucleation. SseF and SseG are known to maintain microcolonies of Salmonella-containing vacuoles close to the microtubule organizing center of infected epithelial cells. During host cell division, these clustered microcolonies prevented the correct localization of members of the chromosomal passenger complex and mitotic kinesin-like protein 1 and consequently prevented cytokinesis. Tetraploidy, arising from a cytokinesis defect, is known to have a deleterious effect on subsequent cell divisions, resulting in either chromosomal instabilities or cell cycle arrest. In infected mice, proliferation of small intestinal epithelial cells was compromised in an SseF/SseG-dependent manner, suggesting that cytokinesis failure caused by S Typhimurium delays epithelial cell turnover in the intestine.

  4. Enterococcus infection biology: lessons from invertebrate host models.

    PubMed

    Yuen, Grace J; Ausubel, Frederick M

    2014-03-01

    The enterococci are commensals of the gastrointestinal tract of many metazoans, from insects to humans. While they normally do not cause disease in the intestine, they can become pathogenic when they infect sites outside of the gut. Recently, the enterococci have become important nosocomial pathogens, with the majority of human enterococcal infections caused by two species, Enterococcus faecalis and Enterococcus faecium. Studies using invertebrate infection models have revealed insights into the biology of enterococcal infections, as well as general principles underlying host innate immune defense. This review highlights recent findings on Enterococcus infection biology from two invertebrate infection models, the greater wax moth Galleria mellonella and the free-living bacteriovorous nematode Caenorhabditis elegans. PMID:24585051

  5. Host Transcriptional Profiles and Immunopathologic Response following Mycobacterium avium subsp. paratuberculosis Infection in Mice

    PubMed Central

    Shin, Min-Kyoung; Park, Hongtae; Shin, Seung Won; Jung, Myunghwan; Lee, Su-Hyung; Kim, Dae-Yong; Yoo, Han Sang

    2015-01-01

    Paratuberculosis or Johne’s disease is a chronic granulomatous enteropathy in ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP) infection. In the present study, we examined the host response to MAP infection in spleens of mice in order to investigate the host immunopathology accompanying host-pathogen interaction. Transcriptional profiles of the MAP-infected mice at 3 and 6 weeks p.i. showed severe histopathological changes, whereas those at 12 weeks p.i. displayed reduced lesion severity in the spleen and liver. MAP-infected mice at 3 and 6 weeks p.i. showed up-regulation of interferon-related genes, scavenger receptor, and complement components, suggesting an initial innate immune reaction, such as macrophage activation, bactericidal activity, and macrophage invasion of MAP. Concurrently, MAP-infected mice at 3 and 6 weeks p.i. were also suggested to express M2 macrophage phenotype with up-regulation of Mrc1, and Marco and down-regulation of MHC class II, Ccr7, and Irf5, and canonical pathways related to the T cell response including ICOS-ICOSL signaling in T helper cells, calcium-induced T lymphocyte apoptosis, and CD28 signaling in T helper cell. These results provide information which furthers the understanding of the immunopathologic response to MAP infection in mice, thereby providing insights valuable for research into the pathogenesis for MAP infection. PMID:26439498

  6. Toxoplasma exports dense granule proteins beyond the vacuole to the host cell nucleus and rewires the host genome expression.

    PubMed

    Bougdour, Alexandre; Tardieux, Isabelle; Hakimi, Mohamed-Ali

    2014-03-01

    Toxoplasma gondii is the most widespread apicomplexan parasite and occupies a large spectrum of niches by infecting virtually any warm-blooded animals. As an obligate intracellular parasite, Toxoplasma has evolved a repertoire of strategies to fine-tune the cellular environment in an optimal way to promote growth and persistence in host tissues hence increasing the chance to be transmitted to new hosts. Short and long-term intracellular survival is associated with Toxoplasma ability to both evade the host deleterious immune defences and to stimulate a beneficial immune balance by governing host cell gene expression. It is only recently that parasite proteins responsible for driving these transcriptional changes have been identified. While proteins contained in the apical secretory Rhoptry organelle have already been identified as bona fide secreted effectors that divert host signalling pathways, recent findings revealed that dense granule proteins should be added to the growing list of effectors as they reach the host cell cytoplasm and nucleus and target various host cell pathways in the course of cell infection. Herein, we emphasize on a novel subfamily of dense granule residentproteins, exemplified with the GRA16 and GRA24 members we recently discovered as both are exported beyond the vacuole-containing parasites and reach the host cell nucleus to reshape the host genome expression.

  7. Real-time PCR detection of host-mediated cyanophage gene transcripts during infection of a natural Microcystis aeruginosa population.

    PubMed

    Yoshida, Mitsuhiro; Yoshida, Takashi; Yoshida-Takashima, Yukari; Kashima, Aki; Hiroishi, Shingo

    2010-01-01

    The aim of this study was to develop a quantitative real-time reverse transcription-PCR (real-time RT-PCR) assay to detect and quantify mRNA of cyanophages within infected Microcystis aeruginosa cells in a freshwater pond. Laboratory-based data showed that the relative abundance of the cyanophage g91 mRNA within host cells increased before cyanophage numbers increased in culture. This transcriptional pattern indicated the kinetics of the viral infection suggesting the real-time RT-PCR method to be a potential tool for environmental monitoring of cyanophage infections. In this field survey, the numbers of infected M. aeruginosa cell populations estimated from cyanophage numbers were low at 0.01-2.9 cells mL(-1). The highest relative abundance of phage g91 RNA (10(-2) per rnpB transcript) was at about the same levels of expression as laboratory-based growth data for Ma-LMM01 (estimated density of infected host cells: 10(5) cells mL(-1)); and was observed when cyanophage numbers rapidly increased (as well as a decrease in host cell numbers). Quantification of cyanophage numbers is important to understand ecological relationships between the phage and its hosts. Our data suggest the quantification of phage gene transcripts within a natural host cell population to be a strong tool for investigating the quantitative effects of phage lysis during infection of the host population.

  8. Infection by retroviral vectors outside of their host range in the presence of replication-defective adenovirus.

    PubMed Central

    Adams, R M; Wang, M; Steffen, D; Ledley, F D

    1995-01-01

    Retrovirus infection is normally limited to cells within a specific host range which express a cognate receptor that is recognized by the product of the env gene. We describe retrovirus infection of cells outside of their normal host range when the infection is performed in the presence of a replication-defective adenovirus (dl312). In the presence of adenovirus, several different ecotropic vectors are shown to infect human cell lines (HeLa and PLC/PRF), and a xenotropic vector is shown to infect murine cells (NIH 3T3). Infectivity is demonstrated by 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) staining, selection with G418 for neomycin resistance, and PCR identification of the provirus in infected cells. Infectivity is quantitatively dependent upon both the concentration of adenovirus (10(6) to 10(8) PFU/ml) and the concentration of retrovirus. Infection requires the simultaneous presence of adenovirus in the retrovirus infection medium and is not stimulated by preincubation and removal of adenovirus from the cells before retrovirus infection. The presence of adenovirus is shown to enhance the uptake of fluorescently labeled retrovirus particles into cells outside of their normal host range, demonstrating that the adenovirus enhances viral entry into cells in the absence of the recognized cognate receptor. This observation suggests new opportunities for developing safe retroviral vectors for gene therapy and new mechanisms for the pathogenesis of retroviral disease. PMID:7853530

  9. The Cnes2 locus on mouse chromosome 17 regulates host defense against cryptococcal infection through pleiotropic effects on host immunity.

    PubMed

    Shourian, Mitra; Flaczyk, Adam; Angers, Isabelle; Mindt, Barbara C; Fritz, Jörg H; Qureshi, Salman T

    2015-12-01

    The genetic basis of natural susceptibility to progressive Cryptococcus neoformans infection is not well understood. Using C57BL/6 and CBA/J inbred mice, we previously identified three chromosomal regions associated with C. neoformans susceptibility (Cnes1, Cnes2, and Cnes3). To validate and characterize the role of Cnes2 during the host response, we constructed a congenic strain on the C57BL/6 background (B6.CBA-Cnes2). Phenotypic analysis of B6.CBA-Cnes2 mice 35 days after C. neoformans infection showed a significant reduction of fungal burden in the lungs and spleen with higher pulmonary expression of gamma interferon (IFN-γ) and interleukin-12 (IL-12), lower expression of IL-4, IL-5, and IL-13, and an absence of airway epithelial mucus production compared to that in C57BL/6 mice. Multiparameter flow cytometry of infected lungs also showed a significantly higher number of neutrophils, exudate macrophages, CD11b(+) dendritic cells, and CD4(+) cells in B6.CBA-Cnes2 than in C57BL/6 mice. The activation state of recruited macrophages and dendritic cells was also significantly increased in B6.CBA-Cnes2 mice. Taken together, these findings demonstrate that the Cnes2 interval is a potent regulator of host defense, immune responsiveness, and differential Th1/Th2 polarization following C. neoformans infection.

  10. Immunodetection and subcellular localization of Mal de Río Cuarto virus P9-1 protein in infected plant and insect host cells.

    PubMed

    Guzmán, Fabiana A; Arneodo, Joel D; Pons, Amalia B Saavedra; Truol, Graciela A; Luque, Andrés V; Conci, Luis R

    2010-08-01

    Mal de Río Cuarto virus (MRCV), a member of the genus Fijivirus, family Reoviridae, has a genome consisting of 10 dsRNA segments. The segment 9 (S9) possesses two non-overlapping open reading frames (ORF-1 and ORF-2) encoding two putative proteins, MRCV P9-1 and MRCV P9-2, both of unknown function. The MRCV S9 ORF-1 was RT-PCR amplified, expressed in pET-15b vector, and the recombinant protein produced was used to raise an antiserum in rabbit. Western blot with the specific MRCV P9-1 antiserum detected a protein of about 39 kDa molecular weight present in crude protein extracts from infected plants and insects. However, no reaction was observed when this antiserum was tested against purified virus. In contrast, only virus particles were detected by a MRCV-coat antiserum used as a validation control. These results suggest that MRCV S9 ORF-1 encodes a non-structural protein of MRCV. Immunoelectron microscopy assays confirmed these results, and localized the MRCV P9-1 protein exclusively in electron-dense granular viroplasms within the cytoplasm of infected plants and insects cells. As viroplasms are believed to be the replication sites of reoviruses, the intracellular location of MRCV P9-1 protein suggests that it might be involved in the assembly process of MRCV particles. PMID:20419342

  11. The nuclear protein Sam68 is cleaved by the FMDV 3C protease redistributing Sam68 to the cytoplasm during FMDV infection of host cells

    SciTech Connect

    Lawrence, Paul; Schafer, Elizabeth A.; Rieder, Elizabeth

    2012-03-30

    Picornavirus infection can lead to disruption of nuclear pore traffic, shut-off of cell translation machinery, and cleavage of proteins involved in cellular signal transduction and the innate response to infection. Here, we demonstrated that the FMDV 3C{sup pro} induced the cleavage of nuclear RNA-binding protein Sam68 C-terminus containing the nuclear localization sequence (NLS). Consequently, it stimulated the redistribution of Sam68 to the cytoplasm. The siRNA knockdown of Sam68 resulted in a 1000-fold reduction in viral titers, which prompted us to study the effect of Sam68 on FMDV post-entry events. Interestingly, Sam68 interacts with the internal ribosomal entry site within the 5 Prime non-translated region of the FMDV genome, and Sam68 knockdown decreased FMDV IRES-driven activity in vitro suggesting that it could modulate translation of the viral genome. The results uncover a novel role for Sam68 in the context of picornaviruses and the proteolysis of a new cellular target of the FMDV 3C{sup pro}.

  12. Contrasting Lifestyles Within the Host Cell.

    PubMed

    Di Russo Case, Elizabeth; Samuel, James E

    2016-02-01

    Intracellular bacterial pathogens have evolved to exploit the protected niche provided within the boundaries of a eukaryotic host cell. Upon entering a host cell, some bacteria can evade the adaptive immune response of its host and replicate in a relatively nutrient-rich environment devoid of competition from other host flora. Growth within a host cell is not without their hazards, however. Many pathogens enter their hosts through receptor-mediated endocytosis or phagocytosis, two intracellular trafficking pathways that terminate in a highly degradative organelle, the phagolysosome. This usually deadly compartment is maintained at a low pH and contains degradative enzymes and reactive oxygen species, resulting in an environment to which few bacterial species are adapted. Some intracellular pathogens, such as Shigella, Listeria, Francisella, and Rickettsia, escape the phagosome to replicate within the cytosol of the host cell. Bacteria that remain within a vacuole either alter the trafficking of their initial phagosomal compartment or adapt to survive within the harsh environment it will soon become. In this chapter, we focus on the mechanisms by which different vacuolar pathogens either evade lysosomal fusion, as in the case of Mycobacterium and Chlamydia, or allow interaction with lysosomes to varying degrees, such as Brucella and Coxiella, and their specific adaptations to inhabit a replicative niche. PMID:26999394

  13. Contrasting Lifestyles Within the Host Cell

    PubMed Central

    Case, Elizabeth Di Russo; Samuel, James E.

    2015-01-01

    CHAPTER SUMMARY Intracellular bacterial pathogens have evolved to exploit the protected niche provided within the boundaries of a eukaryotic host cell. Upon entering a host cell, some bacteria can evade the adaptive immune response of its host, and replicate in a relatively nutrient-rich environment devoid of competition from other host flora. Growth within a host cell is not without its hazards, however. Many pathogens enter their hosts through receptor-mediated endocytosis or phagocytosis, two intracellular trafficking pathways that terminate in a highly degradative organelle, the phagolysosome. This usually deadly compartment is maintained at a low pH, and contains degradative enzymes, and reactive oxygen species resulting in an environment to which few bacterial species are adapted. Some intracellular pathogens, like Shigella, Listeria, Francisella, and Rickettsia escape the phagosome to replicate within the cytosol of the host cell. Bacteria that remain within a vacuole either alter the trafficking of their initial phagosomal compartment or adapt to survive within the harsh environment it will soon become. In this chapter, we focus on the mechanisms by which different vacuolar pathogens either evade lysosomal fusion, as in the case of Mycobacterium and Chlamydia, or allow interaction with lysosomes to varying degrees, such as Brucella and Coxiella, and their specific adaptations to inhabit a replicative niche. PMID:26999394

  14. Host response to nontuberculous mycobacterial infections of current clinical importance.

    PubMed

    Orme, Ian M; Ordway, Diane J

    2014-09-01

    The nontuberculous mycobacteria are a large group of acid-fast bacteria that are very widely distributed in the environment. While Mycobacterium avium was once regarded as innocuous, its high frequency as a cause of disseminated disease in HIV-positive individuals illustrated its potential as a pathogen. Much more recently, there is growing evidence that the incidence of M. avium and related nontuberculous species is increasing in immunocompetent individuals. The same has been observed for M. abscessus infections, which are very difficult to treat; accordingly, this review focuses primarily on these two important pathogens. Like the host response to M. tuberculosis infections, the host response to these infections is of the TH1 type but there are some subtle and as-yet-unexplained differences.

  15. Host Response to Nontuberculous Mycobacterial Infections of Current Clinical Importance

    PubMed Central

    Orme, Ian M.

    2014-01-01

    The nontuberculous mycobacteria are a large group of acid-fast bacteria that are very widely distributed in the environment. While Mycobacterium avium was once regarded as innocuous, its high frequency as a cause of disseminated disease in HIV-positive individuals illustrated its potential as a pathogen. Much more recently, there is growing evidence that the incidence of M. avium and related nontuberculous species is increasing in immunocompetent individuals. The same has been observed for M. abscessus infections, which are very difficult to treat; accordingly, this review focuses primarily on these two important pathogens. Like the host response to M. tuberculosis infections, the host response to these infections is of the TH1 type but there are some subtle and as-yet-unexplained differences. PMID:24914222

  16. Host-pathogen reorganisation during host cell entry by Chlamydia trachomatis.

    PubMed

    Nans, Andrea; Ford, Charlotte; Hayward, Richard D

    2015-01-01

    Chlamydia trachomatis is obligate intracellular bacterial pathogen that remains a significant public health burden worldwide. A critical early event during infection is chlamydial entry into non-phagocytic host epithelial cells. Like other Gram-negative bacteria, C. trachomatis uses a type III secretion system (T3SS) to deliver virulence effector proteins into host cells. These effectors trigger bacterial uptake and promote bacterial survival and replication within the host cell. In this review, we highlight recent cryo-electron tomography that has provided striking insights into the initial interactions between Chlamydia and its host. We describe the polarised structure of extracellular C. trachomatis elementary bodies (EBs), and the supramolecular organisation of T3SS complexes on the EB surface, in addition to the changes in host and pathogen architecture that accompany bacterial internalisation and EB encapsulation into early intracellular vacuoles. Finally, we consider the implications for further understanding the mechanism of C. trachomatis entry and how this might relate to those of other bacteria and viruses.

  17. Host cytoplasmic processing bodies assembled by Trypanosoma cruzi during infection exert anti-parasitic activity.

    PubMed

    Seto, Eri; Onizuka, Yoko; Nakajima-Shimada, Junko

    2015-12-01

    Processing bodies (PBs) are cytoplasmic granules containing mRNAs and proteins involved in translation and degradation of mRNAs. PBs are constitutively present in cells and are induced to accumulate when external stressors including microbial infection are applied to cells, followed by a rapid translational arrest. We have examined the impact of Trypanosoma cruzi (T. cruzi, Tc) infection on host cytoplasmic PB assembly. Within 24h post-infection, we found the average number of PB foci per cell increased by more than 2-fold. Protein levels of PB components were unaltered during infection. These results indicated that Tc infection caused accumulation of PBs by changing the localization pattern of PB protein components. To elucidate the role of the accumulated PBs on Tc infection, we knocked down PBs using a siRNA specific for PB components EDC4 and Lsm14A, which are involved in mRNA decapping and translational repression, respectively. We observed that the inhibition of PB accumulation significantly enhanced the infectivity and growth of intracellular amastigotes. Depletion of PBs did not affect nitric oxide (NO) production during Tc infection, indicating that the growth promotion was not caused by modulation of NO-mediated killing of Tc. Our results suggest that the accumulated PBs partially contribute to anti-parasitic responses by manipulating the host's mRNA metabolism.

  18. Host cell proteases: critical determinants of coronavirus tropism and pathogenesis

    PubMed Central

    Millet, Jean Kaoru; Whittaker, Gary R.

    2015-01-01

    Coronaviruses are a large group of enveloped, single-stranded positive-sense RNA viruses that infect a wide range of avian and mammalian species, including humans. The emergence of deadly human coronaviruses, severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) have bolstered research in these viral and often zoonotic pathogens. While coronavirus cell and tissue tropism, host range, and pathogenesis are initially controlled by interactions between the spike envelope glycoprotein and host cell receptor, it is becoming increasingly apparent that proteolytic activation of spike by host cell proteases also plays a critical role. Coronavirus spike proteins are the main determinant of entry as they possess both receptor binding and fusion functions. Whereas binding to the host cell receptor is an essential first step in establishing infection, the proteolytic activation step is often critical for the fusion function of spike, as it allows for controlled release of the fusion peptide into target cellular membranes. Coronaviruses have evolved multiple strategies for proteolytic activation of spike, and a large number of host proteases have been shown to proteolytically process the spike protein. These include, but are not limited to, endosomal cathepsins, cell surface transmembrane protease/serine (TMPRSS) proteases, furin, and trypsin. This review focuses on the diversity of strategies coronaviruses have evolved to proteolytically activate their fusion protein during spike protein biosynthesis and the critical entry step of their life cycle, and highlights important findings on how proteolytic activation of coronavirus spike influences tissue and cell tropism, host range and pathogenicity. PMID:25445340

  19. Phage infection of an environmentally relevant marine bacterium alters host metabolism and lysate composition

    PubMed Central

    Ankrah, Nana Yaw D; May, Amanda L; Middleton, Jesse L; Jones, Daniel R; Hadden, Mary K; Gooding, Jessica R; LeCleir, Gary R; Wilhelm, Steven W; Campagna, Shawn R; Buchan, Alison

    2014-01-01

    Viruses contribute to the mortality of marine microbes, consequentially altering biological species composition and system biogeochemistry. Although it is well established that host cells provide metabolic resources for virus replication, the extent to which infection reshapes host metabolism at a global level and the effect of this alteration on the cellular material released following viral lysis is less understood. To address this knowledge gap, the growth dynamics, metabolism and extracellular lysate of roseophage-infected Sulfitobacter sp. 2047 was studied using a variety of techniques, including liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based metabolomics. Quantitative estimates of the total amount of carbon and nitrogen sequestered into particulate biomass indicate that phage infection redirects ∼75% of nutrients into virions. Intracellular concentrations for 82 metabolites were measured at seven time points over the infection cycle. By the end of this period, 71% of the detected metabolites were significantly elevated in infected populations, and stable isotope-based flux measurements showed that these cells had elevated metabolic activity. In contrast to simple hypothetical models that assume that extracellular compounds increase because of lysis, a profile of metabolites from infected cultures showed that >70% of the 56 quantified compounds had decreased concentrations in the lysate relative to uninfected controls, suggesting that these small, labile nutrients were being utilized by surviving cells. These results indicate that virus-infected cells are physiologically distinct from their uninfected counterparts, which has implications for microbial community ecology and biogeochemistry. PMID:24304672

  20. Global Reprogramming of Host SUMOylation during Influenza Virus Infection

    PubMed Central

    Domingues, Patricia; Golebiowski, Filip; Tatham, Michael H.; Lopes, Antonio M.; Taggart, Aislynn; Hay, Ronald T.; Hale, Benjamin G.

    2015-01-01

    Summary Dynamic nuclear SUMO modifications play essential roles in orchestrating cellular responses to proteotoxic stress, DNA damage, and DNA virus infection. Here, we describe a non-canonical host SUMOylation response to the nuclear-replicating RNA pathogen, influenza virus, and identify viral RNA polymerase activity as a major contributor to SUMO proteome remodeling. Using quantitative proteomics to compare stress-induced SUMOylation responses, we reveal that influenza virus infection triggers unique re-targeting of SUMO to 63 host proteins involved in transcription, mRNA processing, RNA quality control, and DNA damage repair. This is paralleled by widespread host deSUMOylation. Depletion screening identified ten virus-induced SUMO targets as potential antiviral factors, including C18orf25 and the SMC5/6 and PAF1 complexes. Mechanistic studies further uncovered a role for SUMOylation of the PAF1 complex component, parafibromin (CDC73), in potentiating antiviral gene expression. Our global characterization of influenza virus-triggered SUMO redistribution provides a proteomic resource to understand host nuclear SUMOylation responses to infection. PMID:26549460

  1. Variably lytic infection dynamics of large Bacteroidetes podovirus phi38:1 against two Cellulophaga baltica host strains.

    PubMed

    Dang, Vinh T; Howard-Varona, Cristina; Schwenck, Sarah; Sullivan, Matthew B

    2015-11-01

    Bacterial viruses (phages) influence global biogeochemical cycles by modulating bacterial mortality, metabolic output and evolution. However, our understanding of phage infections is limited by few methods and environmentally relevant model systems. Prior work showed that Cellulophaga baltica phage ϕ38:1 infects its original host lytically, and an alternative host either delayed lytically or lysogenically. Here we investigate these infections through traditional and marker-based approaches, and introduce geneELISA for high-throughput examination of phage-host interactions. All methods confirmed the lytic, original host infection (70-80 min latent period; approximately eight phages produced per cell), but alternative host assays were more challenging. A 4.5 h experiment detected no phage production by plaque assay, whereas phageFISH and geneELISA revealed phage genome replication and a latent period ≥ 150 min. Longer experiments (26 h) suggested an 11 h latent period and a burst size of 871 by plaque assay, whereas phageFISH identified cell lysis starting at < 5 h and lasting to 11 h, but for only 7% to 21.5% of infected cells, respectively, and with ∼ 39 phages produced per cell. These findings help resolve the nature of the alternative host infection as delayed lytic and offer solutions to methodological challenges for studying inefficient phage-host interactions. PMID:26248067

  2. Aquatic viruses induce host cell death pathways and its application.

    PubMed

    Reshi, Latif; Wu, Jen-Leih; Wang, Hao-Ven; Hong, Jiann-Ruey

    2016-01-01

    Virus infections of mammalian and animal cells consist of a series of events. As intracellular parasites, viruses rely on the use of host cellular machinery. Through the use of cell culture and molecular approaches over the past decade, our knowledge of the biology of aquatic viruses has grown exponentially. The increase in aquaculture operations worldwide has provided new approaches for the transmission of aquatic viruses that include RNA and DNA viruses. Therefore, the struggle between the virus and the host for control of the cell's death machinery is crucial for survival. Viruses are obligatory intracellular parasites and, as such, must modulate apoptotic pathways to control the lifespan of their host to complete their replication cycle. This paper updates the discussion on the detailed mechanisms of action that various aquatic viruses use to induce cell death pathways in the host, such as Bad-mediated, mitochondria-mediated, ROS-mediated and Fas-mediated cell death circuits. Understanding how viruses exploit the apoptotic pathways of their hosts may provide great opportunities for the development of future potential therapeutic strategies and pathogenic insights into different aquatic viral diseases.

  3. Dual Analysis of the Murine Cytomegalovirus and Host Cell Transcriptomes Reveal New Aspects of the Virus-Host Cell Interface

    PubMed Central

    Juranic Lisnic, Vanda; Babic Cac, Marina; Lisnic, Berislav; Trsan, Tihana; Mefferd, Adam; Das Mukhopadhyay, Chitrangada; Cook, Charles H.; Jonjic, Stipan; Trgovcich, Joanne

    2013-01-01

    Major gaps in our knowledge of pathogen genes and how these gene products interact with host gene products to cause disease represent a major obstacle to progress in vaccine and antiviral drug development for the herpesviruses. To begin to bridge these gaps, we conducted a dual analysis of Murine Cytomegalovirus (MCMV) and host cell transcriptomes during lytic infection. We analyzed the MCMV transcriptome during lytic infection using both classical cDNA cloning and sequencing of viral transcripts and next generation sequencing of transcripts (RNA-Seq). We also investigated the host transcriptome using RNA-Seq combined with differential gene expression analysis, biological pathway analysis, and gene ontology analysis. We identify numerous novel spliced and unspliced transcripts of MCMV. Unexpectedly, the most abundantly transcribed viral genes are of unknown function. We found that the most abundant viral transcript, recently identified as a noncoding RNA regulating cellular microRNAs, also codes for a novel protein. To our knowledge, this is the first viral transcript that functions both as a noncoding RNA and an mRNA. We also report that lytic infection elicits a profound cellular response in fibroblasts. Highly upregulated and induced host genes included those involved in inflammation and immunity, but also many unexpected transcription factors and host genes related to development and differentiation. Many top downregulated and repressed genes are associated with functions whose roles in infection are obscure, including host long intergenic noncoding RNAs, antisense RNAs or small nucleolar RNAs. Correspondingly, many differentially expressed genes cluster in biological pathways that may shed new light on cytomegalovirus pathogenesis. Together, these findings provide new insights into the molecular warfare at the virus-host interface and suggest new areas of research to advance the understanding and treatment of cytomegalovirus-associated diseases. PMID:24086132

  4. Respiratory infections may reflect deficiencies in host defense mechanisms.

    PubMed

    Reynolds, H Y

    1985-02-01

    Serious respiratory tract infections are rare in the healthy individual and most of the nuisance morbidity that occurs results from nasopharyngeal viral infections that many people get once or twice a year. The economic impact from these upper respiratory tract infections is appreciable, however, in terms of absenteeism from school or work, but unfortunately there is little that can be done to ward them off in a practical way. Pneumonia is an infrequent lifetime experience for most non-smoking adults and when it occurs, unusual circumstances may pertain--a particularly virulent microorganism is in circulation, or perhaps one has been exposed to a newly recognized germ, such as has occurred with Legionella species in the past 8 years or so. What protects us the great majority of the time is a very effective network of respiratory tract host defenses. These include many mechanical and anatomical barrier mechanisms concentrated in nose and throat; mucociliary clearance, coughing and mucosal immunoglobulins in the conducting airways and in the air-exchange region of the alveolar structures, phagocytes, opsonins, complement, surfactant and many other factors combine to clear infectious agents. The ability to mount an inflammatory response in the alveoli may represent the maximal and ultimate expression of local host defense. In some way these host defenses are combating constantly the influx of micro-organisms, usually inhaled or aspirated into the airways, that try to gain a foothold on the mucosal surface and colonize it. But many general changes in overall health such as debility, poor nutrition, metabolic derangements, bone marrow suppression and perhaps aging promote abnormal microbial colonization and undermine the body's defenses that try to cope with the situation. It is a dynamic struggle. The departure from normal respiratory health may not be obvious immediately to the patient or to the physician and repeated episodes of infection or persisting symptoms of

  5. Glycosaminoglycan receptors facilitate infection of mammalian cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A growing list of viruses has been reported to use more than one receptor for binding and internalization during infection of the host cell. Sialic acid residues or glycosaminoglycans, such as heparin sulfate, frequently function in this scenario, as a first contact, charge based, low affinity bindi...

  6. Chlamydial Lung Infection Induces Transient IL-9 Production Which Is Redundant for Host Defense against Primary Infection

    PubMed Central

    Peng, Ying; Gao, Xiaoling; Yang, Jie; Shekhar, Sudhanshu; Wang, Shuhe; Fan, Yijun; Yang, Xi

    2015-01-01

    IL-9/Th9 responses are recently found to be important for innate and adaptive immunity particularly in parasitic infections. To date, the study on the role of IL-9 in bacterial infections is limited and the reported data are contradictory. One reported function of IL-9/Th9 is to modulate Th1/Th17 responses. Since our and others’ previous work has shown a critical role of Th1 and Th17 cells in host defense against chlamydial lung infection, we here examined the role of IL-9 responses in Chlamydia muridarum (Cm) lung infection, particularly its effect on Th1 and Th17 responses and outcome infection. Our data showed quick but transient IL-9 production in the lung following infection, peaking at day 3 and back to baseline around day 7. CD4+ T cell was the major source of IL-9 production in the lung infection. Blockade of endogenous IL-9 using neutralizing antibody failed to change Interferon-γ (IFN-γ) and IL-17 production by cultured spleen mononuclear cells isolated from Cm infected mice. Similarly, in vivo neutralization of IL-9 failed to show significant effect on T cell (Th1 and Th17) and antibody responses (IgA, IgG1 and IgG2a). Consistently, the neutralization of IL-9 had no significant effect on disease process, including body weight change, bacterial burden and histopathological score. The data suggest that IL-9 production following chlamydial lung infection is redundant for host defense against the intracellular bacteria. PMID:25646821

  7. HIV: master of the host cell

    PubMed Central

    Arendt, Christopher W; Littman, Dan R

    2001-01-01

    The human immunodeficiency virus has evolved various mechanisms to exploit its host cells, including the interruption and augmentation of signal transduction pathways. Recently, two DNA microarray studies have illustrated a remarkably broad-based perturbation in host transcriptional responses, which is in part mediated by the HIV-encoded Nef protein. HIV therefore seems to function as a 'master regulator' of cellular gene expression. PMID:11737949

  8. The Gametocytes of Leucocytozoon sabrazesi Infect Chicken Thrombocytes, Not Other Blood Cells

    PubMed Central

    Zhao, Wenting; Liu, Jianwen; Xu, Ruixue; Zhang, Cui; Pang, Qin; Chen, Xin; Liu, Shengfa; Hong, Lingxian; Yuan, Jing; Li, Xiaotong; Chen, Yixin; Li, Jian; Su, Xin-zhuan

    2015-01-01

    Leucocytozoon parasites infect a large number of avian hosts, including domestic chicken, and cause significant economical loss to the poultry industry. Although the transmission stages of the parasites were observed in avian blood cells more than a century ago, the specific host cell type(s) that the gametocytes infect remain uncertain. Because all the avian blood cells, including red blood cells (RBCs), are nucleated, and the developing parasites dramatically change the morphology of the infected host cells, it has been difficult to identify Leucocytozoon infected host cell(s). Here we use cell-type specific antibodies to investigate the identities of the host cells infected by Leucocytozoon sabrazesi gametocytes. Anti-RBC antibodies stained RBCs membrane strongly, but not the parasite-infected cells, ruling out the possibility of RBCs being the infected host cells. Antibodies recognizing various leukocytes including heterophils, monocytes, lymphocytes, and macrophages did not stain the infected cells either. Antisera raised against a peptide of the parasite cytochrome B (CYTB) stained parasite-infected cells and some leukocytes, particularly cells with a single round nucleus as well as clear/pale cytoplasm suggestive of thrombocytes. Finally, a monoclonal antibody known to specifically bind chicken thrombocytes also stained the infected cells, confirming that L. sabrazesi gametocytes develop within chicken thrombocytes. The identification of L. sabrazesi infected host cell solves a long unresolved puzzle and provides important information for studying parasite invasion of host cells and for developing reagents to interrupt parasite transmission. PMID:26218846

  9. Uropathogenic Escherichia coli Epigenetically Manipulate Host Cell Death Pathways.

    PubMed

    Zhang, Zhengguo; Wang, Ming; Eisel, Florian; Tchatalbachev, Svetlin; Chakraborty, Trinad; Meinhardt, Andreas; Bhushan, Sudhanshu

    2016-04-01

    Urinary tract infections caused by uropathogenic Escherichia coli (UPEC) pathovars belong to the most frequent infections in human. It is well established that UPEC can subvert innate immune responses, but the role of UPEC in interfering with host cell death pathways is not known. Here, we show that UPEC abrogates activation of the host cell prosurvival protein kinase B signaling pathway, which results in the activation of mammalian forkhead box O (FOXO) transcription factors. Although FOXOs were localized in the nucleus and showed increased DNA-binding activity, no change in the expression levels of FOXO target genes were observed. UPEC can suppress BIM expression induced by LY249002, which results in attenuation of caspase 3 activation and blockage of apoptosis. Mechanistically, BIM expression appears to be epigenetically silenced by a decrease in histone 4 acetylation at the BIM promoter site. Taken together, these results suggest that UPEC can epigenetically silence BIM expression, a molecular switch that prevents apoptosis.

  10. Identification of host genes involved in geminivirus infection using a reverse genetics approach.

    PubMed

    Lozano-Durán, Rosa; Rosas-Díaz, Tábata; Luna, Ana P; Bejarano, Eduardo R

    2011-01-01

    Geminiviruses, like all viruses, rely on the host cell machinery to establish a successful infection, but the identity and function of these required host proteins remain largely unknown. Tomato yellow leaf curl Sardinia virus (TYLCSV), a monopartite geminivirus, is one of the causal agents of the devastating Tomato yellow leaf curl disease (TYLCD). The transgenic 2IRGFP N. benthamiana plants, used in combination with Virus Induced Gene Silencing (VIGS), entail an important potential as a tool in reverse genetics studies to identify host factors involved in TYLCSV infection. Using these transgenic plants, we have made an accurate description of the evolution of TYLCSV replication in the host in both space and time. Moreover, we have determined that TYLCSV and Tobacco rattle virus (TRV) do not dramatically influence each other when co-infected in N. benthamiana, what makes the use of TRV-induced gene silencing in combination with TYLCSV for reverse genetic studies feasible. Finally, we have tested the effect of silencing candidate host genes on TYLCSV infection, identifying eighteen genes potentially involved in this process, fifteen of which had never been implicated in geminiviral infections before. Seven of the analyzed genes have a potential anti-viral effect, whereas the expression of the other eleven is required for a full infection. Interestingly, almost half of the genes altering TYLCSV infection play a role in postranslational modifications. Therefore, our results provide new insights into the molecular mechanisms underlying geminivirus infections, and at the same time reveal the 2IRGFP/VIGS system as a powerful tool for functional reverse genetics studies. PMID:21818318

  11. Identification of Host Genes Involved in Geminivirus Infection Using a Reverse Genetics Approach

    PubMed Central

    Luna, Ana P.; Bejarano, Eduardo R.

    2011-01-01

    Geminiviruses, like all viruses, rely on the host cell machinery to establish a successful infection, but the identity and function of these required host proteins remain largely unknown. Tomato yellow leaf curl Sardinia virus (TYLCSV), a monopartite geminivirus, is one of the causal agents of the devastating Tomato yellow leaf curl disease (TYLCD). The transgenic 2IRGFP N. benthamiana plants, used in combination with Virus Induced Gene Silencing (VIGS), entail an important potential as a tool in reverse genetics studies to identify host factors involved in TYLCSV infection. Using these transgenic plants, we have made an accurate description of the evolution of TYLCSV replication in the host in both space and time. Moreover, we have determined that TYLCSV and Tobacco rattle virus (TRV) do not dramatically influence each other when co-infected in N. benthamiana, what makes the use of TRV-induced gene silencing in combination with TYLCSV for reverse genetic studies feasible. Finally, we have tested the effect of silencing candidate host genes on TYLCSV infection, identifying eighteen genes potentially involved in this process, fifteen of which had never been implicated in geminiviral infections before. Seven of the analyzed genes have a potential anti-viral effect, whereas the expression of the other eleven is required for a full infection. Interestingly, almost half of the genes altering TYLCSV infection play a role in postranslational modifications. Therefore, our results provide new insights into the molecular mechanisms underlying geminivirus infections, and at the same time reveal the 2IRGFP/VIGS system as a powerful tool for functional reverse genetics studies. PMID:21818318

  12. Lytic infection of Lactococcus lactis by bacteriophages Tuc2009 and c2 triggers alternative transcriptional host responses.

    PubMed

    Ainsworth, Stuart; Zomer, Aldert; Mahony, Jennifer; van Sinderen, Douwe

    2013-08-01

    Here we present an entire temporal transcriptional profile of Lactococcus lactis subsp. cremoris UC509.9 undergoing lytic infection with two distinct bacteriophages, Tuc2009 and c2. Furthermore, corresponding high-resolution whole-phage genome tiling arrays of both bacteriophages were performed throughout lytic infection. Whole-genome microarrays performed at various time points postinfection demonstrated a rather modest impact on host transcription. The majority of changes in the host transcriptome occur during late infection stages; few changes in host gene transcription occur during the immediate and early infection stages. Alterations in the L. lactis UC509.9 transcriptome during lytic infection appear to be phage specific, with relatively few differentially transcribed genes shared between cells infected with Tuc2009 and those infected with c2. Despite the apparent lack of a coordinated general phage response, three themes common to both infections were noted: alternative transcription of genes involved in catabolic flux and energy production, differential transcription of genes involved in cell wall modification, and differential transcription of genes involved in the conversion of ribonucleotides to deoxyribonucleotides. The transcriptional profiles of both bacteriophages during lytic infection generally correlated with the findings of previous studies and allowed the confirmation of previously predicted promoter sequences. In addition, the host transcriptional response to lysogenization with Tuc2009 was monitored along with tiling array analysis of Tuc2009 in the lysogenic state. Analysis identified 44 host genes with altered transcription during lysogeny, 36 of which displayed levels of transcription significantly reduced from those for uninfected cells.

  13. Catabolism of host-derived compounds during extracellular bacterial infections.

    PubMed

    Meadows, Jamie A; Wargo, Matthew J

    2014-02-01

    Efficient catabolism of host-derived compounds is essential for bacterial survival and virulence. While these links in intracellular bacteria are well studied, such studies in extracellular bacteria lag behind, mostly for technical reasons. The field has identified important metabolic pathways, but the mechanisms by which they impact infection and in particular, establishing the importance of a compound's catabolism versus alternate metabolic roles has been difficult. In this review we will examine evidence for catabolism during extracellular bacterial infections in animals and known or potential roles in virulence. In the process, we point out key gaps in the field that will require new or newly adapted techniques.

  14. Plasmodium species: master renovators of their host cells.

    PubMed

    de Koning-Ward, Tania F; Dixon, Matthew W A; Tilley, Leann; Gilson, Paul R

    2016-08-01

    Plasmodium parasites, the causative agents of malaria, have developed elaborate strategies that they use to survive and thrive within different intracellular environments. During the blood stage of infection, the parasite is a master renovator of its erythrocyte host cell, and the changes in cell morphology and function that are induced by the parasite promote survival and contribute to the pathogenesis of severe malaria. In this Review, we discuss how Plasmodium parasites use the protein trafficking motif Plasmodium export element (PEXEL), protease-mediated polypeptide processing, a novel translocon termed the Plasmodium translocon of exported proteins (PTEX) and exomembranous structures to export hundreds of proteins to discrete subcellular locations in the host erythrocytes, which enables the parasite to gain access to vital nutrients and to evade the immune defence mechanisms of the host.

  15. Insect-specific flavivirus infection is restricted by innate immunity in the vertebrate host.

    PubMed

    Tree, Maya O; McKellar, Dexter R; Kieft, Kristopher J; Watson, Alan M; Ryman, Kate D; Conway, Michael J

    2016-10-01

    Arboviruses are a large group of viruses that are transmitted by arthropods including ticks and mosquitoes. The global diversity of arboviruses is unknown; however, theoretical studies have estimated that over 2,000 mosquito-borne flaviviruses may exist. An increasing number of flaviviruses can only infect insect cells. We hypothesize that insect-specific flaviviruses (ISFVs) represent model genetic precursors to pathogenic flaviviruses, although the genetic mechanisms required for adaptation to vertebrate hosts are unclear. In this study, we determined that Kamiti River virus (KRV) infection was inhibited by innate immunity pathways in vertebrate cells. KRV infection of IRF3,5,7(-/-) mouse embryonic fibroblasts led to low levels of viral protein production and shedding of infectious progeny. These data suggest that ISFVs cannot evade vertebrate innate immune pathways. Identifying cellular pathways and genetic changes that are required for adaptation of arthropod-specific arboviruses to vertebrate hosts is critical to understanding emerging infectious disease. PMID:27433779

  16. Quantitative proteomic identification of host factors involved in the Salmonella typhimurium infection cycle.

    PubMed

    Kaloyanova, Dora; Vogels, Mijke; van Balkom, Bas W M; Helms, J Bernd

    2015-01-01

    Quantitative proteomics, based on stable isotope labeling by amino acids in cell culture (SILAC), can be used to identify host proteins involved in the intracellular interplay with pathogens. This method allows identification of proteins subject to degradation or upregulation in response to intracellular infection. It can also be used to study intracellular dynamics (trafficking) of proteins in response to the infection. Here, we describe the analysis of changes in protein profiles determined in Golgi-enriched fractions isolated from cells that were either mock-infected or infected with Salmonella typhimurium. Using the SILAC approach we were able to identify 105 proteins in Golgi-enriched fractions that were significantly changed in their abundance as a result of Salmonella infection.

  17. Host shutoff is a conserved phenotype of gammaherpesvirus infection and is orchestrated exclusively from the cytoplasm.

    PubMed

    Covarrubias, Sergio; Richner, Justin M; Clyde, Karen; Lee, Yeon J; Glaunsinger, Britt A

    2009-09-01

    Lytic infection with the two human gammaherpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), leads to significant depletion of the cellular transcriptome. This host shutoff phenotype is driven by the conserved herpesviral alkaline exonuclease, termed SOX in KSHV and BGLF5 in EBV, which in gammaherpesviruses has evolved the genetically separable ability to target cellular mRNA. We now show that host shutoff is also a prominent consequence of murine gammaherpesvirus 68 (MHV68) infection, which is widely used as a model system to study pathogenesis of these viruses in vivo. The effector of MHV68-induced host shutoff is its SOX homolog, here termed muSOX. There is remarkable functional conservation of muSOX host shutoff activities with those of KSHV SOX, including the recently described ability of SOX to induce mRNA hyperadenylation in the nucleus as well as cause nuclear relocalization of the poly(A) binding protein. SOX and muSOX localize to both the nucleus and cytoplasm of infected cells. Using spatially restricted variants of these proteins, we go on to demonstrate that all known host shutoff-related activities of SOX and muSOX are orchestrated exclusively from the cytoplasm. These results have important mechanistic implications for how SOX and muSOX target nascent cellular transcripts in the nucleus. Furthermore, our findings establish MHV68 as a new, genetically tractable model to study host shutoff.

  18. Interferon Response in Hepatitis C Virus (HCV) Infection: Lessons from Cell Culture Systems of HCV Infection.

    PubMed

    Sung, Pil Soo; Shin, Eui-Cheol; Yoon, Seung Kew

    2015-01-01

    Hepatitis C virus (HCV) is a positive-stranded RNA virus that infects approximately 130-170 million people worldwide. In 2005, the first HCV infection system in cell culture was established using clone JFH-1, which was isolated from a Japanese patient with fulminant HCV infection. JFH-1 replicates efficiently in hepatoma cells and infectious virion particles are released into the culture supernatant. The development of cell culture-derived HCV (HCVcc) systems has allowed us to understand how hosts respond to HCV infection and how HCV evades host responses. Although the mechanisms underlying the different outcomes of HCV infection are not fully understood, innate immune responses seem to have a critical impact on the outcome of HCV infection, as demonstrated by the prognostic value of IFN-λ gene polymorphisms among patients with chronic HCV infection. Herein, we review recent research on interferon response in HCV infection, particularly studies using HCVcc infection systems.

  19. Adhesins and host serum factors drive Yop translocation by yersinia into professional phagocytes during animal infection.

    PubMed

    Maldonado-Arocho, Francisco J; Green, Carlos; Fisher, Michael L; Paczosa, Michelle K; Mecsas, Joan

    2013-01-01

    Yersinia delivers Yops into numerous types of cultured cells, but predominantly into professional phagocytes and B cells during animal infection. The basis for this cellular tropism during animal infection is not understood. This work demonstrates that efficient and specific Yop translocation into phagocytes by Yersinia pseudotuberculosis (Yptb) is a multi-factorial process requiring several adhesins and host complement. When WT Yptb or a multiple adhesin mutant strain, ΔailΔinvΔyadA, colonized tissues to comparable levels, ΔailΔinvΔyadA translocated Yops into significantly fewer cells, demonstrating that these adhesins are critical for translocation into high numbers of cells. However, phagocytes were still selectively targeted for translocation, indicating that other bacterial and/or host factors contribute to this function. Complement depletion showed that complement-restricted infection by ΔailΔinvΔyadA but not WT, indicating that adhesins disarm complement in mice either by prevention of opsonophagocytosis or by suppressing production of pro-inflammatory cytokines. Furthermore, in the absence of the three adhesins and complement, the spectrum of cells targeted for translocation was significantly altered, indicating that Yersinia adhesins and complement direct Yop translocation into neutrophils during animal infection. In summary, these findings demonstrate that in infected tissues, Yersinia uses adhesins both to disarm complement-dependent killing and to efficiently translocate Yops into phagocytes.

  20. Fungal Cell Gigantism during Mammalian Infection

    PubMed Central

    Zaragoza, Oscar; García-Rodas, Rocío; Nosanchuk, Joshua D.; Cuenca-Estrella, Manuel; Rodríguez-Tudela, Juan Luis; Casadevall, Arturo

    2010-01-01

    The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 µm in diameter and capsules resistant to stripping with γ-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20–50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens. PMID:20585557

  1. Fungal cell gigantism during mammalian infection.

    PubMed

    Zaragoza, Oscar; García-Rodas, Rocío; Nosanchuk, Joshua D; Cuenca-Estrella, Manuel; Rodríguez-Tudela, Juan Luis; Casadevall, Arturo

    2010-01-01

    The interaction between fungal pathogens with the host frequently results in morphological changes, such as hyphae formation. The encapsulated pathogenic fungus Cryptococcus neoformans is not considered a dimorphic fungus, and is predominantly found in host tissues as round yeast cells. However, there is a specific morphological change associated with cryptococcal infection that involves an increase in capsule volume. We now report another morphological change whereby gigantic cells are formed in tissue. The paper reports the phenotypic characterization of giant cells isolated from infected mice and the cellular changes associated with giant cell formation. C. neoformans infection in mice resulted in the appearance of giant cells with cell bodies up to 30 microm in diameter and capsules resistant to stripping with gamma-radiation and organic solvents. The proportion of giant cells ranged from 10 to 80% of the total lung fungal burden, depending on infection time, individual mice, and correlated with the type of immune response. When placed on agar, giant cells budded to produce small daughter cells that traversed the capsule of the mother cell at the speed of 20-50 m/h. Giant cells with dimensions that approximated those in vivo were observed in vitro after prolonged culture in minimal media, and were the oldest in the culture, suggesting that giant cell formation is an aging-dependent phenomenon. Giant cells recovered from mice displayed polyploidy, suggesting a mechanism by which gigantism results from cell cycle progression without cell fission. Giant cell formation was dependent on cAMP, but not on Ras1. Real-time imaging showed that giant cells were engaged, but not engulfed by phagocytic cells. We describe a remarkable new strategy for C. neoformans to evade the immune response by enlarging cell size, and suggest that gigantism results from replication without fission, a phenomenon that may also occur with other fungal pathogens.

  2. IL-17 is essential for host defense against cutaneous Staphylococcus aureus infection in mice.

    PubMed

    Cho, John S; Pietras, Eric M; Garcia, Nairy C; Ramos, Romela Irene; Farzam, David M; Monroe, Holly R; Magorien, Julie E; Blauvelt, Andrew; Kolls, Jay K; Cheung, Ambrose L; Cheng, Genhong; Modlin, Robert L; Miller, Lloyd S

    2010-05-01

    Staphylococcus aureus is the most common cause of skin and soft tissue infections, and rapidly emerging antibiotic-resistant strains are creating a serious public health concern. If immune-based therapies are to be an alternative to antibiotics, greater understanding is needed of the protective immune response against S. aureus infection in the skin. Although neutrophil recruitment is required for immunity against S. aureus, a role for T cells has been suggested. Here, we used a mouse model of S. aureus cutaneous infection to investigate the contribution of T cells to host defense. We found that mice deficient in gammadelta but not alphabeta T cells had substantially larger skin lesions with higher bacterial counts and impaired neutrophil recruitment compared with WT mice. This neutrophil recruitment was dependent upon epidermal Vgamma5+ gammadelta T cell production of IL-17, but not IL-21 and IL-22. Furthermore, IL-17 induction required IL-1, TLR2, and IL-23 and was critical for host defense, since IL-17R-deficient mice had a phenotype similar to that of gammadelta T cell-deficient mice. Importantly, gammadelta T cell-deficient mice inoculated with S. aureus and treated with a single dose of recombinant IL-17 had lesion sizes and bacterial counts resembling those of WT mice, demonstrating that IL-17 could restore the impaired immunity in these mice. Our study defines what we believe to be a novel role for IL-17-producing epidermal gammadelta T cells in innate immunity against S. aureus cutaneous infection.

  3. The Dialogue of the Host-Parasite Relationship: Leishmania spp. and Trypanosoma cruzi Infection.

    PubMed

    de Morais, Carlos Gustavo Vieira; Castro Lima, Ana Karina; Terra, Rodrigo; dos Santos, Rosiane Freire; Da-Silva, Silvia Amaral Gonçalves; Dutra, Patrícia Maria Lourenço

    2015-01-01

    The intracellular protozoa Leishmania spp. and Trypanosoma cruzi and the causative agents of Leishmaniasis and Chagas disease, respectively, belong to the Trypanosomatidae family. Together, these two neglected tropical diseases affect approximately 25 million people worldwide. Whether the host can control the infection or develops disease depends on the complex interaction between parasite and host. Parasite surface and secreted molecules are involved in triggering specific signaling pathways essential for parasite entry and intracellular survival. The recognition of the parasite antigens by host immune cells generates a specific immune response. Leishmania spp. and T. cruzi have a multifaceted repertoire of strategies to evade or subvert the immune system by interfering with a range of signal transduction pathways in host cells, which causes the inhibition of the protective response and contributes to their persistence in the host. The current therapeutic strategies in leishmaniasis and trypanosomiasis are very limited. Efficacy is variable, toxicity is high, and the emergence of resistance is increasingly common. In this review, we discuss the molecular basis of the host-parasite interaction of Leishmania and Trypanosoma cruzi infection and their mechanisms of subverting the immune response and how this knowledge can be used as a tool for the development of new drugs.

  4. The Dialogue of the Host-Parasite Relationship: Leishmania spp. and Trypanosoma cruzi Infection

    PubMed Central

    de Morais, Carlos Gustavo Vieira; Castro Lima, Ana Karina; dos Santos, Rosiane Freire; Da-Silva, Silvia Amaral Gonçalves; Dutra, Patrícia Maria Lourenço

    2015-01-01

    The intracellular protozoa Leishmania spp. and Trypanosoma cruzi and the causative agents of Leishmaniasis and Chagas disease, respectively, belong to the Trypanosomatidae family. Together, these two neglected tropical diseases affect approximately 25 million people worldwide. Whether the host can control the infection or develops disease depends on the complex interaction between parasite and host. Parasite surface and secreted molecules are involved in triggering specific signaling pathways essential for parasite entry and intracellular survival. The recognition of the parasite antigens by host immune cells generates a specific immune response. Leishmania spp. and T. cruzi have a multifaceted repertoire of strategies to evade or subvert the immune system by interfering with a range of signal transduction pathways in host cells, which causes the inhibition of the protective response and contributes to their persistence in the host. The current therapeutic strategies in leishmaniasis and trypanosomiasis are very limited. Efficacy is variable, toxicity is high, and the emergence of resistance is increasingly common. In this review, we discuss the molecular basis of the host-parasite interaction of Leishmania and Trypanosoma cruzi infection and their mechanisms of subverting the immune response and how this knowledge can be used as a tool for the development of new drugs. PMID:26090399

  5. Distinct Pathogenesis and Host Responses during Infection of C. elegans by P. aeruginosa and S. aureus

    PubMed Central

    Irazoqui, Javier E.; Troemel, Emily R.; Feinbaum, Rhonda L.; Luhachack, Lyly G.; Cezairliyan, Brent O.; Ausubel, Frederick M.

    2010-01-01

    The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR) protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs). Because our data suggest that neither the P. aeruginosa nor the S. aureus–triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C. elegans, with

  6. Intraspecies host specificity of a single-stranded RNA virus infecting a marine photosynthetic protist is determined at the early steps of infection.

    PubMed

    Mizumoto, Hiroyuki; Tomaru, Yuji; Takao, Yoshitake; Shirai, Yoko; Nagasaki, Keizo

    2007-02-01

    Viruses are extremely abundant in seawater and are believed to be significant pathogens to photosynthetic protists (microalgae). Recently, several novel RNA viruses were found to infect marine photosynthetic protists; one of them is HcRNAV, which infects Heterocapsa circularisquama (Dinophyceae). There are two distinct ecotypes of HcRNAV with complementary intraspecies host ranges. Nucleotide sequence comparison between them revealed remarkable differences in the coat protein coding gene resulting in a high frequency of amino acid substitutions. However, the detailed mechanism supporting this intraspecies host specificity is still unknown. In this study, virus inoculation experiments were conducted with compatible and incompatible host-virus combinations to investigate the mechanism determining intraspecies host specificity. Cells were infected by adding a virus suspension directly to a host culture or by transfecting viral RNA into host cells by particle bombardment. Virus propagation was monitored by Northern blot analysis with a negative-strand-specific RNA probe, transmission electron microscopy, and a cell lysis assay. With compatible host-virus combinations, propagation of infectious progeny occurred regardless of the inoculation method used. When incompatible combinations were used, direct addition of a virus suspension did not even result in viral RNA replication, while in host cells transfected with viral RNA, infective progeny virus particles with a host range encoded by the imported viral RNA were propagated. This indicates that the intraspecies host specificity of HcRNAV is determined by the upstream events of virus infection. This is the first report describing the reproductive steps of an RNA virus infecting a photosynthetic protist at the molecular level.

  7. Fungal infections of the immunocompromised host: clinical and laboratory aspects.

    PubMed Central

    Musial, C E; Cockerill, F R; Roberts, G D

    1988-01-01

    Fungal infections of the immunocompromised host are being seen with greater frequency than ever before. In addition, a growing list of unusual and unexpected etiologic agents presents a unique and difficult challenge to the clinician and microbiologist. The clinical manifestations of opportunistic fungal infections are often not characteristic and, in many instances, may prevent a rapid diagnosis from being made. Clinical microbiology laboratories should consider any organism as a potential etiologic agent. This requires that all fungi recovered from immunocompromised patients be thoroughly identified and reported so that their clinical significance may be assessed. This review presents a brief discussion of the clinical and laboratory aspects of some fungal infections seen in this important group of patients. PMID:3069198

  8. Long-term live imaging reveals cytosolic immune responses of host hepatocytes against Plasmodium infection and parasite escape mechanisms.

    PubMed

    Prado, Monica; Eickel, Nina; De Niz, Mariana; Heitmann, Anna; Agop-Nersesian, Carolina; Wacker, Rahel; Schmuckli-Maurer, Jacqueline; Caldelari, Reto; Janse, Chris J; Khan, Shahid M; May, Jürgen; Meyer, Christian G; Heussler, Volker T

    2015-01-01

    Plasmodium parasites are transmitted by Anopheles mosquitoes to the mammalian host and actively infect hepatocytes after passive transport in the bloodstream to the liver. In their target host hepatocyte, parasites reside within a parasitophorous vacuole (PV). In the present study it was shown that the parasitophorous vacuole membrane (PVM) can be targeted by autophagy marker proteins LC3, ubiquitin, and SQSTM1/p62 as well as by lysosomes in a process resembling selective autophagy. The dynamics of autophagy marker proteins in individual Plasmodium berghei-infected hepatocytes were followed by live imaging throughout the entire development of the parasite in the liver. Although the host cell very efficiently recognized the invading parasite in its vacuole, the majority of parasites survived this initial attack. Successful parasite development correlated with the gradual loss of all analyzed autophagy marker proteins and associated lysosomes from the PVM. However, other autophagic events like nonselective canonical autophagy in the host cell continued. This was indicated as LC3, although not labeling the PVM anymore, still localized to autophagosomes in the infected host cell. It appears that growing parasites even benefit from this form of nonselective host cell autophagy as an additional source of nutrients, as in host cells deficient for autophagy, parasite growth was retarded and could partly be rescued by the supply of additional amino acid in the medium. Importantly, mouse infections with P. berghei sporozoites confirmed LC3 dynamics, the positive effect of autophagy activation on parasite growth, and negative effects upon autophagy inhibition.

  9. Regulation of Host Cell Transcriptional Physiology by the Avian Pneumovirus Provides Key Insights into Host-Pathogen Interactions

    PubMed Central

    Munir, Shirin; Kapur, Vivek

    2003-01-01

    Infection with a viral pathogen triggers several pathways in the host cell that are crucial to eliminating infection, as well as those that are used by the virus to enhance its replication and virulence. We have here used suppression subtractive hybridization and cDNA microarray analyses to characterize the host transcriptional response in an avian pneumovirus model of infection. The results of our investigations reveal a dynamic host response that includes the regulation of genes with roles in a vast array of cellular functions as well as those that have not been described previously. The results show a considerable upregulation in transcripts representing the interferon-activated family of genes, predicted to play a role in virus replication arrest. The analysis also identified transcripts for proinflammatory leukocyte chemoattractants, adhesion molecules, and complement that were upregulated and may account for the inflammatory pathology that is the hallmark of viral respiratory infection. Interestingly, alterations in the transcription of several genes in the ubiquitin and endosomal protein trafficking pathways were observed, suggesting a role for these pathways in virus maturation and budding. Taken together, the results of our investigations provide key insights into individual genes and pathways that constitute the host cell's response to avian pneumovirus infection, and they have enabled the development of resources and a model of host-pathogen interaction for an important avian respiratory tract pathogen. PMID:12663796

  10. Cellular Aspects of Shigella Pathogenesis: Focus on the Manipulation of Host Cell Processes

    PubMed Central

    Killackey, Samuel A.; Sorbara, Matthew T.; Girardin, Stephen E.

    2016-01-01

    Shigella is a Gram-negative bacterium that is responsible for shigellosis. Over the years, the study of Shigella has provided a greater understanding of how the host responds to bacterial infection, and how bacteria have evolved to effectively counter the host defenses. In this review, we provide an update on some of the most recent advances in our understanding of pivotal processes associated with Shigella infection, including the invasion into host cells, the metabolic changes that occur within the bacterium and the infected cell, cell-to-cell spread mechanisms, autophagy and membrane trafficking, inflammatory signaling and cell death. This recent progress sheds a new light into the mechanisms underlying Shigella pathogenesis, and also more generally provides deeper understanding of the complex interplay between host cells and bacterial pathogens in general. PMID:27066460

  11. Host genetics determine susceptibility to avian influenza infection and transmission dynamics

    PubMed Central

    Ruiz-Hernandez, Raul; Mwangi, William; Peroval, Marylene; Sadeyen, Jean-Remy; Ascough, Stephanie; Balkissoon, Devanand; Staines, Karen; Boyd, Amy; McCauley, John; Smith, Adrian; Butter, Colin

    2016-01-01

    Host-genetic control of influenza virus infection has been the object of little attention. In this study we determined that two inbred lines of chicken differing in their genetic background , Lines 0 and C-B12, were respectively relatively resistant and susceptible to infection with the low pathogenicity influenza virus A/Turkey/England/647/77 as defined by substantial differences in viral shedding trajectories. Resistant birds, although infected, were unable to transmit virus to contact birds, as ultimately only the presence of a sustained cloacal shedding (and not oropharyngeal shedding) was critical for transmission. Restriction of within-bird transmission of virus occurred in the resistant line, with intra-nares or cloacal infection resulting in only local shedding and failing to transmit fully through the gastro-intestinal-pulmonary tract. Resistance to infection was independent of adaptive immune responses, including the expansion of specific IFNγ secreting cells or production of influenza-specific antibody. Genetic resistance to a novel H9N2 virus was less robust, though significant differences between host genotypes were still clearly evident. The existence of host-genetic determination of the outcome of influenza infection offers tools for the further dissection of this regulation and also for understanding the mechanisms of influenza transmission within and between birds. PMID:27279280

  12. Host genetics determine susceptibility to avian influenza infection and transmission dynamics.

    PubMed

    Ruiz-Hernandez, Raul; Mwangi, William; Peroval, Marylene; Sadeyen, Jean-Remy; Ascough, Stephanie; Balkissoon, Devanand; Staines, Karen; Boyd, Amy; McCauley, John; Smith, Adrian; Butter, Colin

    2016-01-01

    Host-genetic control of influenza virus infection has been the object of little attention. In this study we determined that two inbred lines of chicken differing in their genetic background , Lines 0 and C-B12, were respectively relatively resistant and susceptible to infection with the low pathogenicity influenza virus A/Turkey/England/647/77 as defined by substantial differences in viral shedding trajectories. Resistant birds, although infected, were unable to transmit virus to contact birds, as ultimately only the presence of a sustained cloacal shedding (and not oropharyngeal shedding) was critical for transmission. Restriction of within-bird transmission of virus occurred in the resistant line, with intra-nares or cloacal infection resulting in only local shedding and failing to transmit fully through the gastro-intestinal-pulmonary tract. Resistance to infection was independent of adaptive immune responses, including the expansion of specific IFNγ secreting cells or production of influenza-specific antibody. Genetic resistance to a novel H9N2 virus was less robust, though significant differences between host genotypes were still clearly evident. The existence of host-genetic determination of the outcome of influenza infection offers tools for the further dissection of this regulation and also for understanding the mechanisms of influenza transmission within and between birds.

  13. Retroviral Infections in Sheep and Goats: Small Ruminant Lentiviruses and Host Interaction

    PubMed Central

    Larruskain, Amaia; Jugo, Begoña M.

    2013-01-01

    Small ruminant lentiviruses (SRLV) are members of the Retrovirus family comprising the closely related Visna/Maedi Virus (VMV) and the Caprine Arthritis-Encephalitis Virus (CAEV), which infect sheep and goats. Both infect cells of the monocyte/macrophage lineage and cause lifelong infections. Infection by VMV and CAEV can lead to Visna/Maedi (VM) and Caprine Arthritis-Encephalitis (CAE) respectively, slow progressive inflammatory diseases primarily affecting the lungs, nervous system, joints and mammary glands. VM and CAE are distributed worldwide and develop over a period of months or years, always leading to the death of the host, with the consequent economic and welfare implications. Currently, the control of VM and CAE relies on the control of transmission and culling of infected animals. However, there is evidence that host genetics play an important role in determining Susceptibility/Resistance to SRLV infection and disease progression, but little work has been performed in small ruminants. More research is necessary to understand the host-SRLV interaction. PMID:23965529

  14. Host genetics determine susceptibility to avian influenza infection and transmission dynamics.

    PubMed

    Ruiz-Hernandez, Raul; Mwangi, William; Peroval, Marylene; Sadeyen, Jean-Remy; Ascough, Stephanie; Balkissoon, Devanand; Staines, Karen; Boyd, Amy; McCauley, John; Smith, Adrian; Butter, Colin

    2016-01-01

    Host-genetic control of influenza virus infection has been the object of little attention. In this study we determined that two inbred lines of chicken differing in their genetic background , Lines 0 and C-B12, were respectively relatively resistant and susceptible to infection with the low pathogenicity influenza virus A/Turkey/England/647/77 as defined by substantial differences in viral shedding trajectories. Resistant birds, although infected, were unable to transmit virus to contact birds, as ultimately only the presence of a sustained cloacal shedding (and not oropharyngeal shedding) was critical for transmission. Restriction of within-bird transmission of virus occurred in the resistant line, with intra-nares or cloacal infection resulting in only local shedding and failing to transmit fully through the gastro-intestinal-pulmonary tract. Resistance to infection was independent of adaptive immune responses, including the expansion of specific IFNγ secreting cells or production of influenza-specific antibody. Genetic resistance to a novel H9N2 virus was less robust, though significant differences between host genotypes were still clearly evident. The existence of host-genetic determination of the outcome of influenza infection offers tools for the further dissection of this regulation and also for understanding the mechanisms of influenza transmission within and between birds. PMID:27279280

  15. Impact of host gene polymorphisms on susceptibility to chronic hepatitis B virus infection.

    PubMed

    Moudi, Bita; Heidari, Zahra; Mahmoudzadeh-Sagheb, Hamidreza

    2016-10-01

    Hepatitis B virus (HBV) infection can result in a number of different clinical conditions, including asymptomatic HBV carriers to chronic hepatitis and primary hepatocellular carcinoma. Variations in cytokine genes have been discussed to affect the natural history of HBV infection. These cytokines may involve in the viral binding to the cells, modulating the host immune response to infection and pathological changes in the liver, and affecting the antiviral therapies. Various studies reveal that SNPs play an important role in pathogenesis of HBV. On the other hand, various outcomes of infection cannot be completely shown by genetic factors because these studies have inconsistent results with regard to the possible impacts of host genetic polymorphisms on susceptibility to infection. Therefore, to identify the real effects of host genetic factors in HBV susceptibility and natural history of the disease, studies with large sample size will be needed. In addition, due to the complex interactions of genetic factors it is better to identify synergies of several SNPs. Such studies can provide better insights into the novel methods of diagnosis and treatment. Current review will discuss significant genetic variations in cytokine genes that may affect the susceptibility to the chronic HBV infection. PMID:27346643

  16. A potential target gene for the host-directed therapy of mycobacterial infection in murine macrophages.

    PubMed

    Bao, Zhang; Chen, Ran; Zhang, Pei; Lu, Shan; Chen, Xing; Yao, Yake; Jin, Xiaozheng; Sun, Yilan; Zhou, Jianying

    2016-09-01

    Mycobacterium tuberculosis (MTB), one of the major bacterial pathogens for lethal infectious diseases, is capable of surviving within the phagosomes of host alveolar macrophages; therefore, host genetic variations may alter the susceptibility to MTB. In this study, to identify host genes exploited by MTB during infection, genes were non-selectively inactivated using lentivirus-based antisense RNA methods in Raw264.7 macrophages, and the cells that survived virulent MTB infection were then screened. Following DNA sequencing of the surviving cell clones, 26 host genes affecting susceptibility to MTB were identified and their pathways were analyzed by bioinformatics analysis. In total, 9 of these genes were confirmed as positive regulators of collagen α-5(IV) chain (Col4a5) expression, a gene encoding a type IV collagen subunit present on the cell surface. The knockdown of Col4a5 consistently suppressed intracellular mycobacterial viability, promoting the survival of Raw264.7 macrophages following mycobacterial infection. Furthermore, Col4a5 deficiency lowered the pH levels of intracellular vesicles, including endosomes, lysosomes and phagosomes in the Raw264.7 cells. Finally, the knockdown of Col4a5 post-translationally increased microsomal vacuolar-type H+-ATPase activity in macrophages, leading to the acidification of intracellular vesicles. Our findings reveal a novel role for Col4a5 in the regulation of macrophage responses to mycobacterial infection and identify Col4a5 as a potential target for the host-directed anti-mycobacterial therapy. PMID:27432120

  17. A potential target gene for the host-directed therapy of mycobacterial infection in murine macrophages

    PubMed Central

    Bao, Zhang; Chen, Ran; Zhang, Pei; Lu, Shan; Chen, Xing; Yao, Yake; Jin, Xiaozheng; Sun, Yilan; Zhou, Jianying

    2016-01-01

    Mycobacterium tuberculosis (MTB), one of the major bacterial pathogens for lethal infectious diseases, is capable of surviving within the phagosomes of host alveolar macrophages; therefore, host genetic variations may alter the susceptibility to MTB. In this study, to identify host genes exploited by MTB during infection, genes were non-selectively inactivated using lentivirus-based antisense RNA methods in RAW264.7 macrophages, and the cells that survived virulent MTB infection were then screened. Following DNA sequencing of the surviving cell clones, 26 host genes affecting susceptibility to MTB were identified and their pathways were analyzed by bioinformatics analysis. In total, 9 of these genes were confirmed as positive regulators of collagen α-5(IV) chain (Col4a5) expression, a gene encoding a type IV collagen subunit present on the cell surface. The knockdown of Col4a5 consistently suppressed intracellular mycobacterial viability, promoting the survival of RAW264.7 macrophages following mycobacterial infection. Furthermore, Col4a5 deficiency lowered the pH levels of intracellular vesicles, including endosomes, lysosomes and phagosomes in the RAW264.7 cells. Finally, the knockdown of Col4a5 post-translationally increased microsomal vacuolar-type H+-ATPase activity in macrophages, leading to the acidification of intracellular vesicles. Our findings reveal a novel role for Col4a5 in the regulation of macrophage responses to mycobacterial infection and identify Col4a5 as a potential target for the host-directed anti-mycobacterial therapy. PMID:27432120

  18. Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes.

    PubMed

    Baneth, Gad; Harrus, Shimon; Gal, Arnon; Aroch, Itamar

    2015-02-28

    The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other. PMID:25560923

  19. Resistance and Susceptibility to Malarial Infection: A Host Defense Strategy against Malaria

    PubMed Central

    BAKIR, Hanaa; YONES, Doaa; GALAL, Lamia; HUSEEIN, Enas

    2015-01-01

    Background: In an effort to understand what limits the virulence of malaria parasites in relation to the host genetic and immunogenic background, we investigated the possibility that the parasite and host genotype crossover interactions constrain virulence. Methods: Two groups of mice from different genotypes were used (C57BL/6 (B6) and DBA/2 mice). The mice were infected with a virulent parasite line Plasmodium yoelii 17XL (P. yoelii 17XL). Parasitemia, hematocrit value and lymphocytes yielded by livers and spleens were evaluated. Fluorescence Activated Cell Sorting (FACS) analysis illustrated phenotypic characterization of lymphocytes. Results: Infection with P. yoelii 17XL did not result in the death of DBA/2 mice. In contrast, B6 mice developed significantly high parasitemia and succumbed to death. Using (FACS) analysis, DBA/2 mice were found to experience a marked expansion of interleukin (IL)-2Rβ+ CD3int cells and γδ T cells in the liver, especially in the recovery phase. The expansion of unconventional T cells (i.e. B220+ T cells) was also marked in DBA/2 mice. Conclusion: The outcome of murine malaria infections depends on the dynamic interplay between the immune-mediator and the genotype of the host. PMID:26811732

  20. Host immune response in returning travellers infected with malaria

    PubMed Central

    2012-01-01

    Background Clinical observations suggest that Canadian-born (CB) travellers are prone to more severe malaria, characterized by higher parasite density in the blood, and severe symptoms, such as cerebral malaria and renal failure, than foreign-born travellers (FB) from areas of malaria endemicity. It was hypothesized that host cytokine and chemokine responses differ significantly in CB versus FB patients returning with malaria, contributing to the courses of severity. A more detailed understanding of the profiles of cytokines, chemokines, and endothelial activation may be useful in developing biomarkers and novel therapeutic approaches for malaria. Materials and methods The patient population for the study (n = 186) was comprised of travellers returning to Toronto, Canada between 2007 and 2011. The patient blood samples’ cytokine, chemokine and angiopoietin concentrations were determined using cytokine multiplex assays, and ELISA assays. Results Significantly higher plasma cytokine levels of IL-12 (p40) were observed in CB compared to FB travellers, while epidermal growth factor (EGF) was observed to be higher in FB than CB travellers. Older travellers (55 years old or greater) with Plasmodium vivax infections had significantly higher mean cytokine levels for IL-6 and macrophage colony-stimulating factor (M-CSF) than other adults with P. vivax (ages 18–55). Patients with P. vivax infections had significantly higher mean cytokine levels for monocyte chemotactic protein-1 (MCP-1), and M-CSF than patients with Plasmodium falciparum. Angiopoietin 2 (Ang-2) was higher for patients infected with P. falciparum than P. vivax, especially when comparing just the FB groups. IL-12 (p40) was higher in FB patients with P. vivax compared to P. falciparum. Il-12 (p40) was also higher in patients infected with P. vivax than those infected with Plasmodium ovale. For patients travelling to West Africa, IFN-γ and IL-6 was lower than for patients who were in other regions of Africa

  1. Exploitation of host cells by Burkholderia pseudomallei.

    PubMed

    Stevens, Mark P; Galyov, Edouard E

    2004-04-01

    Intracellular bacterial pathogens have evolved mechanisms to enter and exit eukaryotic cells using the power of actin polymerisation and to subvert the activity of cellular enzymes and signal transduction pathways. The proteins deployed by bacteria to subvert cellular processes often mimic eukaryotic proteins in their structure or function. Studies on the exploitation of host cells by the facultative intracellular pathogen Burkholderia pseudomallei are providing novel insights into the pathogenesis of melioidosis, a serious invasive disease of animals and humans that is endemic in tropical and subtropical areas. B. pseudomallei can invade epithelial cells, survive and proliferate inside phagocytes, escape from endocytic vesicles, form actin-based membrane protrusions and induce host cell fusion. Here we review current understanding of the molecular mechanisms underlying these processes.

  2. Measles Virus Matrix Protein Inhibits Host Cell Transcription.

    PubMed

    Yu, Xuelian; Shahriari, Shadi; Li, Hong-Mei; Ghildyal, Reena

    2016-01-01

    Measles virus (MeV) is a highly contagious virus that still causes annual epidemics in developing countries despite the availability of a safe and effective vaccine. Additionally, importation from endemic countries causes frequent outbreaks in countries where it has been eliminated. The M protein of MeV plays a key role in virus assembly and cytopathogenesis; interestingly, M is localised in nucleus, cytoplasm and membranes of infected cells. We have used transient expression of M in transfected cells and in-cell transcription assays to show that only some MeV M localizes to the nucleus, in addition to cell membranes and the cytoplasm as previously described, and can inhibit cellular transcription via binding to nuclear factors. Additionally, MeV M was able to inhibit in vitro transcription in a dose-dependent manner. Importantly, a proportion of M is also localized to nucleus of MeV infected cells at early times in infection, correlating with inhibition of cellular transcription. Our data show, for the first time, that MeV M may play a role early in infection by inhibiting host cell transcription. PMID:27551716

  3. Measles Virus Matrix Protein Inhibits Host Cell Transcription

    PubMed Central

    Yu, Xuelian; Shahriari, Shadi; Li, Hong-Mei; Ghildyal, Reena

    2016-01-01

    Measles virus (MeV) is a highly contagious virus that still causes annual epidemics in developing countries despite the availability of a safe and effective vaccine. Additionally, importation from endemic countries causes frequent outbreaks in countries where it has been eliminated. The M protein of MeV plays a key role in virus assembly and cytopathogenesis; interestingly, M is localised in nucleus, cytoplasm and membranes of infected cells. We have used transient expression of M in transfected cells and in-cell transcription assays to show that only some MeV M localizes to the nucleus, in addition to cell membranes and the cytoplasm as previously described, and can inhibit cellular transcription via binding to nuclear factors. Additionally, MeV M was able to inhibit in vitro transcription in a dose-dependent manner. Importantly, a proportion of M is also localized to nucleus of MeV infected cells at early times in infection, correlating with inhibition of cellular transcription. Our data show, for the first time, that MeV M may play a role early in infection by inhibiting host cell transcription. PMID:27551716

  4. Using Proteomics to Understand How Leishmania Parasites Survive inside the Host and Establish Infection.

    PubMed

    Veras, Patrícia Sampaio Tavares; Bezerra de Menezes, Juliana Perrone

    2016-08-19

    Leishmania is a protozoan parasite that causes a wide range of different clinical manifestations in mammalian hosts. It is a major public health risk on different continents and represents one of the most important neglected diseases. Due to the high toxicity of the drugs currently used, and in the light of increasing drug resistance, there is a critical need to develop new drugs and vaccines to control Leishmania infection. Over the past few years, proteomics has become an important tool to understand the underlying biology of Leishmania parasites and host interaction. The large-scale study of proteins, both in parasites and within the host in response to infection, can accelerate the discovery of new therapeutic targets. By studying the proteomes of host cells and tissues infected with Leishmania, as well as changes in protein profiles among promastigotes and amastigotes, scientists hope to better understand the biology involved in the parasite survival and the host-parasite interaction. This review demonstrates the feasibility of proteomics as an approach to identify new proteins involved in Leishmania differentiation and intracellular survival.

  5. Using Proteomics to Understand How Leishmania Parasites Survive inside the Host and Establish Infection.

    PubMed

    Veras, Patrícia Sampaio Tavares; Bezerra de Menezes, Juliana Perrone

    2016-01-01

    Leishmania is a protozoan parasite that causes a wide range of different clinical manifestations in mammalian hosts. It is a major public health risk on different continents and represents one of the most important neglected diseases. Due to the high toxicity of the drugs currently used, and in the light of increasing drug resistance, there is a critical need to develop new drugs and vaccines to control Leishmania infection. Over the past few years, proteomics has become an important tool to understand the underlying biology of Leishmania parasites and host interaction. The large-scale study of proteins, both in parasites and within the host in response to infection, can accelerate the discovery of new therapeutic targets. By studying the proteomes of host cells and tissues infected with Leishmania, as well as changes in protein profiles among promastigotes and amastigotes, scientists hope to better understand the biology involved in the parasite survival and the host-parasite interaction. This review demonstrates the feasibility of proteomics as an approach to identify new proteins involved in Leishmania differentiation and intracellular survival. PMID:27548150

  6. Using Proteomics to Understand How Leishmania Parasites Survive inside the Host and Establish Infection

    PubMed Central

    Veras, Patrícia Sampaio Tavares; Bezerra de Menezes, Juliana Perrone

    2016-01-01

    Leishmania is a protozoan parasite that causes a wide range of different clinical manifestations in mammalian hosts. It is a major public health risk on different continents and represents one of the most important neglected diseases. Due to the high toxicity of the drugs currently used, and in the light of increasing drug resistance, there is a critical need to develop new drugs and vaccines to control Leishmania infection. Over the past few years, proteomics has become an important tool to understand the underlying biology of Leishmania parasites and host interaction. The large-scale study of proteins, both in parasites and within the host in response to infection, can accelerate the discovery of new therapeutic targets. By studying the proteomes of host cells and tissues infected with Leishmania, as well as changes in protein profiles among promastigotes and amastigotes, scientists hope to better understand the biology involved in the parasite survival and the host-parasite interaction. This review demonstrates the feasibility of proteomics as an approach to identify new proteins involved in Leishmania differentiation and intracellular survival. PMID:27548150

  7. The late endosomal adaptor p14 is a macrophage host-defense factor against Salmonella infection.

    PubMed

    Taub, Nicole; Nairz, Manfred; Hilber, Diana; Hess, Michael W; Weiss, Günter; Huber, Lukas A

    2012-06-01

    The outcome of an infection depends on the balance between host resistance and bacterial virulence. Here, we show that the late endosomal adaptor p14 (also known as LAMTOR2) is one of the components for cellular host defense against the intracellular pathogen Salmonella enterica serovar Typhimurium. During Salmonella infection, the complex of p14 and MP1 is required for the accurately timed transport of Salmonella through the endolysosomal system. Loss of p14 opens a time window that allows Salmonella to populate a replication niche, in which early and late antimicrobial effector systems, comprising NADPH phagocytic oxidase and inducible nitric oxide synthase, respectively, are inappropriately activated. Thus, p14 supports the accurate transport of Salmonella through the endolysosomal system, thereby limiting bacterial replication in both, professional phagocytes and in non-phagocytic cells in vitro, and helps mice to successfully battle Salmonella infection in vivo.

  8. Naturally occurring, nonregressing canine oral papillomavirus infection: host immunity, virus characterization, and experimental infection.

    PubMed

    Nicholls, P K; Klaunberg, B A; Moore, R A; Santos, E B; Parry, N R; Gough, G W; Stanley, M A

    1999-12-20

    Papillomaviruses occasionally cause severe, nonregressing or recurrent infections in their human and animal hosts. The mechanisms underlying these atypical infections are not known. Canine oral papillomavirus (COPV) typically regresses spontaneously and is an important model of mucosal human papillomavirus infections. A severe, naturally occurring, nonregressing COPV infection provided an opportunity to investigate some aspects of viral pathogenicity and host immunity. In this case, the papillomas proved refractory to surgical and medical treatments, including autogenous vaccination and vaccination with capsid (L1) virus-like particles. High levels of induced anti-L1 antibodies appeared to have no effect on the infection. The papillomas spread to oesophageal mucosa, perioral haired skin, and remote cutaneous sites. Isolation of COPV from the animal and sequencing of several regions of the viral genome showed no differences to the COPV prototype. Experimental infection of beagle dogs with this viral isolate resulted in the uncomplicated development and regression of oral warts within the usual period, indicating that the virus was not an unusual pathogenic variant. These findings support the hypothesis that the recurrent lesions seen in some human papillomavirus infections, such as recurrent laryngeal papillomatosis, are associated with specific defects in host immunity rather than variations in viral pathogenicity. PMID:10600607

  9. Host sphingomyelin increases West Nile virus infection in vivo.

    PubMed

    Martín-Acebes, Miguel A; Gabandé-Rodríguez, Enrique; García-Cabrero, Ana M; Sánchez, Marina P; Ledesma, María Dolores; Sobrino, Francisco; Saiz, Juan-Carlos

    2016-03-01

    Flaviviruses, such as the dengue virus and the West Nile virus (WNV), are arthropod-borne viruses that represent a global health problem. The flavivirus lifecycle is intimately connected to cellular lipids. Among the lipids co-opted by flaviviruses, we have focused on SM, an important component of cellular membranes particularly enriched in the nervous system. After infection with the neurotropic WNV, mice deficient in acid sphingomyelinase (ASM), which accumulate high levels of SM in their tissues, displayed exacerbated infection. In addition, WNV multiplication was enhanced in cells from human patients with Niemann-Pick type A, a disease caused by a deficiency of ASM activity resulting in SM accumulation. Furthermore, the addition of SM to cultured cells also increased WNV infection, whereas treatment with pharmacological inhibitors of SM synthesis reduced WNV infection. Confocal microscopy analyses confirmed the association of SM with viral replication sites within infected cells. Our results unveil that SM metabolism regulates flavivirus infection in vivo and propose SM as a suitable target for antiviral design against WNV.

  10. Characterization of host immune responses in Ebola virus infections.

    PubMed

    Wong, Gary; Kobinger, Gary P; Qiu, Xiangguo

    2014-06-01

    Ebola causes highly lethal hemorrhagic fever in humans with no licensed countermeasures. Its virulence can be attributed to several immunoevasion mechanisms: an early inhibition of innate immunity started by the downregulation of type I interferon, epitope masking and subversion of the adaptive humoural immunity by secreting a truncated form of the viral glycoprotein. Deficiencies in specific and non-specific antiviral responses result in unrestricted viral replication and dissemination in the host, causing death typically within 10 days after the appearance of symptoms. This review summarizes the host immune response to Ebola infection, and highlights the short- and long-term immune responses crucial for protection, which holds implications for the design of future vaccines and therapeutics. PMID:24742338

  11. Characterization of host immune responses in Ebola virus infections.

    PubMed

    Wong, Gary; Kobinger, Gary P; Qiu, Xiangguo

    2014-06-01

    Ebola causes highly lethal hemorrhagic fever in humans with no licensed countermeasures. Its virulence can be attributed to several immunoevasion mechanisms: an early inhibition of innate immunity started by the downregulation of type I interferon, epitope masking and subversion of the adaptive humoural immunity by secreting a truncated form of the viral glycoprotein. Deficiencies in specific and non-specific antiviral responses result in unrestricted viral replication and dissemination in the host, causing death typically within 10 days after the appearance of symptoms. This review summarizes the host immune response to Ebola infection, and highlights the short- and long-term immune responses crucial for protection, which holds implications for the design of future vaccines and therapeutics.

  12. Host-Pathogen Checkpoints and Population Bottlenecks in Persistent and Intracellular Uropathogenic E. coli Bladder Infection

    PubMed Central

    Hannan, Thomas J.; Totsika, Makrina; Mansfield, Kylie J.; Moore, Kate H.; Schembri, Mark A.; Hultgren, Scott J.

    2013-01-01

    Bladder infections affect millions of people yearly, and recurrent symptomatic infections (cystitis) are very common. The rapid increase in infections caused by multi-drug resistant uropathogens threatens to make recurrent cystitis an increasingly troubling public health concern. Uropathogenic E. coli (UPEC) cause the vast majority of bladder infections. Upon entry into the lower urinary tract, UPEC face obstacles to colonization that constitute population bottlenecks, reducing diversity and selecting for fit clones. A critical mucosal barrier to bladder infection is the epithelium (urothelium). UPEC bypass this barrier when they invade urothelial cells and form intracellular bacterial communities (IBCs), a process which requires type 1 pili. IBCs are transient in nature, occurring primarily during acute infection. Chronic bladder infection is common and can be either latent, in the form of the Quiescent Intracellular Reservoir (QIR), or active, in the form of asymptomatic bacteriuria (ASB/ABU) or chronic cystitis. In mice, the fate of bladder infection: QIR, ASB, or chronic cystitis, is determined within the first 24 hours of infection and constitutes a putative host-pathogen mucosal checkpoint that contributes to susceptibility to recurrent cystitis. Knowledge of these checkpoints and bottlenecks is critical for our understanding of bladder infection and efforts to devise novel therapeutic strategies. PMID:22404313

  13. CD8+ T Cells in Leishmania Infections: Friends or Foes?

    PubMed Central

    Stäger, Simona; Rafati, Sima

    2012-01-01

    Host protection against several intracellular pathogens requires the induction of CD8+ T cell responses. CD8+ T cells are potent effector cells that can produce high amounts of pro-inflammatory cytokines and kill infected target cells efficiently. However, a protective role for CD8+ T cells during Leishmania infections is still controversial and largely depends on the infection model. In this review, we discuss the role of CD8+ T cells during various types of Leishmania infections, following vaccination, and as potential immunotherapeutic targets. PMID:22566891

  14. Abundance and Relative Distribution of Frankia Host Infection Groups Under Actinorhizal Alnus glutinosa and Non-actinorhizal Betula nigra Trees.

    PubMed

    Samant, Suvidha; Huo, Tian; Dawson, Jeffrey O; Hahn, Dittmar

    2016-02-01

    Quantitative polymerase chain reaction (qPCR) was used to assess the abundance and relative distribution of host infection groups of the root-nodule forming, nitrogen-fixing actinomycete Frankia in four soils with similar physicochemical characteristics, two of which were vegetated with a host plant, Alnus glutinosa, and two with a non-host plant, Betula nigra. Analyses of DAPI-stained cells at three locations, i.e., at a distance of less than 1 m (near stem), 2.5 m (middle crown), and 3-5 m (crown edge) from the stems of both tree species revealed no statistically significant differences in abundance. Frankiae generally accounted for 0.01 to 0.04 % of these cells, with values between 4 and 36 × 10(5) cells (g soil)(-1). In three out of four soils, abundance of frankiae was significantly higher at locations "near stem" and/or "middle crown" compared to "crown edge," while numbers at these locations were not different in the fourth soil. Frankiae of the Alnus host infection group were dominant in all samples accounting for about 75 % and more of the cells, with no obvious differences with distance to stem. In three of the soils, all of these cells were represented by strain Ag45/Mut15. In the fourth soil that was vegetated with older A. glutinosa trees, about half of these cells belonged to a different subgroup represented by strain ArI3. In all soils, the remaining cells belonged to the Elaeagnus host infection group represented by strain EAN1pec. Casuarina-infective frankiae were not found. Abundance and relative distribution of Frankia host infection groups were similar in soils under the host plant A. glutinosa and the non-host plant B. nigra. Results did thus not reveal any specific effects of plant species on soil Frankia populations. PMID:26143359

  15. Abundance and Relative Distribution of Frankia Host Infection Groups Under Actinorhizal Alnus glutinosa and Non-actinorhizal Betula nigra Trees.

    PubMed

    Samant, Suvidha; Huo, Tian; Dawson, Jeffrey O; Hahn, Dittmar

    2016-02-01

    Quantitative polymerase chain reaction (qPCR) was used to assess the abundance and relative distribution of host infection groups of the root-nodule forming, nitrogen-fixing actinomycete Frankia in four soils with similar physicochemical characteristics, two of which were vegetated with a host plant, Alnus glutinosa, and two with a non-host plant, Betula nigra. Analyses of DAPI-stained cells at three locations, i.e., at a distance of less than 1 m (near stem), 2.5 m (middle crown), and 3-5 m (crown edge) from the stems of both tree species revealed no statistically significant differences in abundance. Frankiae generally accounted for 0.01 to 0.04 % of these cells, with values between 4 and 36 × 10(5) cells (g soil)(-1). In three out of four soils, abundance of frankiae was significantly higher at locations "near stem" and/or "middle crown" compared to "crown edge," while numbers at these locations were not different in the fourth soil. Frankiae of the Alnus host infection group were dominant in all samples accounting for about 75 % and more of the cells, with no obvious differences with distance to stem. In three of the soils, all of these cells were represented by strain Ag45/Mut15. In the fourth soil that was vegetated with older A. glutinosa trees, about half of these cells belonged to a different subgroup represented by strain ArI3. In all soils, the remaining cells belonged to the Elaeagnus host infection group represented by strain EAN1pec. Casuarina-infective frankiae were not found. Abundance and relative distribution of Frankia host infection groups were similar in soils under the host plant A. glutinosa and the non-host plant B. nigra. Results did thus not reveal any specific effects of plant species on soil Frankia populations.

  16. HTLV-I infection: a dynamic struggle between viral persistence and host immunity.

    PubMed

    Lim, Aaron G; Maini, Philip K

    2014-07-01

    Human T-lymphotropic virus type I (HTLV-I) causes chronic infection for which there is no cure or neutralising vaccine. HTLV-I has been clinically linked to the development of adult T-cell leukaemia/lymphoma (ATL), an aggressive blood cancer, and HAM/TSP, a progressive neurological and inflammatory disease. Infected individuals typically mount a large, persistently activated CD8(+) cytotoxic T-lymphocyte (CTL) response against HTLV-I-infected cells, but ultimately fail to effectively eliminate the virus. Moreover, the identification of determinants to disease manifestation has thus far been elusive. A key issue in current HTLV-I research is to better understand the dynamic interaction between persistent infection by HTLV-I and virus-specific host immunity. Recent experimental hypotheses for the persistence of HTLV-I in vivo have led to the development of mathematical models illuminating the balance between proviral latency and activation in the target cell population. We investigate the role of a constantly changing anti-viral immune environment acting in response to the effects of infected T-cell activation and subsequent viral expression. The resulting model is a four-dimensional, non-linear system of ordinary differential equations that describes the dynamic interactions among viral expression, infected target cell activation, and the HTLV-I-specific CTL response. The global dynamics of the model is established through the construction of appropriate Lyapunov functions. Examining the particular roles of viral expression and host immunity during the chronic phase of HTLV-I infection offers important insights regarding the evolution of viral persistence and proposes a hypothesis for pathogenesis. PMID:24583256

  17. Estradiol-Treated Female Mice as Surrogate Hosts for Neisseria gonorrhoeae Genital Tract Infections.

    PubMed

    Jerse, Ann E; Wu, Hong; Packiam, Mathanraj; Vonck, Rachel A; Begum, Afrin A; Garvin, Lotisha E

    2011-01-01

    Historically, animal modeling of gonorrhea has been hampered by the exclusive adaptation of Neisseria gonorrhoeae to humans. Genital tract infection can be established in female mice that are treated with 17β-estradiol, however, and many features of experimental murine infection mimic human infection. Here we review the colonization kinetics and host response to experimental murine gonococcal infection, including mouse strain differences and evidence that IL-17 responses, toll-like receptor 4, and T regulatory cells play a role in infection. We also discuss the strengths and limitations of the mouse system and the potential of transgenic mice to circumvent host restrictions. Additionally, we review studies with genetically defined mutants that demonstrated a role for sialyltransferase and the MtrC-MtrD-MtrE active efflux pump in evading innate defenses in vivo, but not for factors hypothesized to protect against the phagocytic respiratory burst and H(2)O(2)-producing lactobacilli. Studies using estradiol-treated mice have also revealed the existence of non-host-restricted iron sources in the female genital tract and the influence of hormonal factors on colonization kinetics and selection for opacity (Opa) protein expression. Recent work by others with estradiol-treated mice that are transgenic for human carcinoembryonic adhesion molecules (CEACAMs) supports a role for Opa proteins in enhancing cellular attachment and thus reduced shedding of N. gonorrhoeae. Finally we discuss the use of the mouse model in product testing and a recently developed gonorrhea chlamydia coinfection model.

  18. Parasite calcineurin regulates host cell recognition and attachment by apicomplexans

    PubMed Central

    Paul, Aditya S.; Saha, Sudeshna; Engelberg, Klemens; Jiang, Rays H.Y.; Coleman, Bradley I.; Kosber, Aziz L.; Chen, Chun-Ti; Ganter, Markus; Espy, Nicole; Gilberger, Tim W.; Gubbels, Marc-Jan; Duraisingh, Manoj T.

    2015-01-01

    SUMMARY Apicomplexans invade a variety of metazoan host cells through mechanisms involving host cell receptor engagement and secretion of parasite factors to facilitate cellular attachment. We find that the parasite homolog of calcineurin, a calcium-regulated phosphatase complex central to signal transduction in eukaryotes, also contributes to host cell invasion by the malaria parasite Plasmodium falciparum and related Toxoplasma gondii. Using reverse genetic and chemical-genetic approaches, we determine that calcineurin critically regulates and stabilizes attachment of extracellular P. falciparum to host erythrocytes before intracellular entry and has similar functions in host cell engagement by T. gondii. Calcineurin-mediated Plasmodium invasion is strongly associated with host receptors required for host cell recognition and calcineurin function distinguishes this form of receptor-mediated attachment from a second mode of host-parasite adhesion independent of host receptors. This specific role of calcineurin in coordinating physical interactions with host cells highlights an ancestral mechanism for parasitism used by apicomplexans. PMID:26118996

  19. Proteomic Analysis of Rhizoctonia solani Identifies Infection-specific, Redox Associated Proteins and Insight into Adaptation to Different Plant Hosts.

    PubMed

    Anderson, Jonathan P; Hane, James K; Stoll, Thomas; Pain, Nicholas; Hastie, Marcus L; Kaur, Parwinder; Hoogland, Christine; Gorman, Jeffrey J; Singh, Karam B

    2016-04-01

    Rhizoctonia solaniis an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about howR. solanicauses disease. This study capitalizes on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility toR. solaniwhen expressed inNicotiana benthamiana In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806.

  20. Proteomic Analysis of Rhizoctonia solani Identifies Infection-specific, Redox Associated Proteins and Insight into Adaptation to Different Plant Hosts.

    PubMed

    Anderson, Jonathan P; Hane, James K; Stoll, Thomas; Pain, Nicholas; Hastie, Marcus L; Kaur, Parwinder; Hoogland, Christine; Gorman, Jeffrey J; Singh, Karam B

    2016-04-01

    Rhizoctonia solaniis an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about howR. solanicauses disease. This study capitalizes on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility toR. solaniwhen expressed inNicotiana benthamiana In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806. PMID:26811357

  1. Proteomic Analysis of Rhizoctonia solani Identifies Infection-specific, Redox Associated Proteins and Insight into Adaptation to Different Plant Hosts*

    PubMed Central

    Anderson, Jonathan P.; Hane, James K.; Stoll, Thomas; Pain, Nicholas; Hastie, Marcus L.; Kaur, Parwinder; Hoogland, Christine; Gorman, Jeffrey J.; Singh, Karam B.

    2016-01-01

    Rhizoctonia solani is an important root infecting pathogen of a range of food staples worldwide including wheat, rice, maize, soybean, potato and others. Conventional resistance breeding strategies are hindered by the absence of tractable genetic resistance in any crop host. Understanding the biology and pathogenicity mechanisms of this fungus is important for addressing these disease issues, however, little is known about how R. solani causes disease. This study capitalizes on recent genomic studies by applying mass spectrometry based proteomics to identify soluble, membrane-bound and culture filtrate proteins produced under wheat infection and vegetative growth conditions. Many of the proteins found in the culture filtrate had predicted functions relating to modification of the plant cell wall, a major activity required for pathogenesis on the plant host, including a number found only under infection conditions. Other infection related proteins included a high proportion of proteins with redox associated functions and many novel proteins without functional classification. The majority of infection only proteins tested were confirmed to show transcript up-regulation during infection including a thaumatin which increased susceptibility to R. solani when expressed in Nicotiana benthamiana. In addition, analysis of expression during infection of different plant hosts highlighted how the infection strategy of this broad host range pathogen can be adapted to the particular host being encountered. Data are available via ProteomeXchange with identifier PXD002806. PMID:26811357

  2. Toll-Like Receptor 2 Targeted Rectification of Impaired CD8+ T Cell Functions in Experimental Leishmania donovani Infection Reinstates Host Protection

    PubMed Central

    Bandyopadhyay, Syamdas; Kar Mahapatra, Santanu; Paul Chowdhury, Bidisha; Kumar Jha, Mukesh; Das, Shibali; Halder, Kuntal; Bhattacharyya Majumdar, Suchandra; Saha, Bhaskar; Majumdar, Subrata

    2015-01-01

    Leishmania donovani, a protozoan parasite, causes the disease visceral leishmanisis (VL), characterized by inappropriate CD8+ T-cell activation. Therefore, we examined whether the Toll-like Receptor 2 (TLR2) ligand Ara-LAM, a cell wall glycolipid from non-pathogenic Mycobacterium smegmatis, would restore CD8+ T-cell function during VL. We observed that by efficient upregulation of TLR2 signaling-mediated NF-κB translocation and MAPK signaling in CD8+ T-cells (CD25+CD28+IL-12R+IFN-γR+), Ara-LAM triggered signaling resulted in the activation of T-bet, which in turn, induced transcription favourable histone modification at the IFN-γ, perforin, granzyme-B promoter regions in CD8+ T-cells. Thus, we conclude that Ara-LAM induced efficient activation of effector CD8+ T-cells by upregulating the expression of IFN-γ, perforin and granzyme-B in an NF-κB and MAPK induced T-bet dependent manner in VL. PMID:26559815

  3. Premature apoptosis of Chlamydia-infected cells disrupts chlamydial development.

    PubMed

    Ying, Songmin; Pettengill, Matthew; Latham, E Ray; Walch, Axel; Ojcius, David M; Häcker, Georg

    2008-11-15

    The obligate intracellular development of Chlamydia suggests that the bacteria should be vulnerable to premature host cell apoptosis, but because Chlamydia-infected cells are apoptosis resistant, this has never been able to be tested. We have devised a system to circumvent the apoptotic block imposed by chlamydial infection. When the proapoptotic protein Bim(S) was experimentally induced, epithelial cells underwent apoptosis that was not blocked by chlamydial infection. Apoptosis during the developmental cycle prevented the generation of infectious bacteria and caused transcriptional changes of bacterial genes and loss of intracellular ATP. Intriguingly, although apoptosis resulted in destruction of host cell structures and of the Chlamydia inclusion, and prevented generation of elementary bodies, Bim(S) induction in the presence of a caspase inhibitor allowed differentiation into morphologically normal but noninfectious elementary bodies. These data show that chlamydial infection renders host cells apoptosis resistant at a premitochondrial step and demonstrate the consequences of premature apoptosis for development of the bacteria.

  4. Inferring Infection Patterns Based on a Connectivity Map of Host Transcriptional Responses

    PubMed Central

    Han, Lu; He, Haochen; Li, Fei; Cui, Xiuliang; Xie, Dafei; Liu, Yang; Zheng, Xiaofei; Bai, Hui; Wang, Shengqi; Bo, Xiaochen

    2015-01-01

    Host responses to infections represent an important pathogenicity determiner, and delineation of host responses can elucidate pathogenesis processes and inform the development of anti-infection therapies. Low cost, high throughput, easy quantitation, and rich descriptions have made gene expression profiling generated by DNA microarrays an optimal approach for describing host transcriptional responses (HTRs). However, efforts to characterize the landscape of HTRs to diverse pathogens are far from offering a comprehensive view. Here, we developed an HTR Connectivity Map based on systematic assessment of pairwise similarities of HTRs to 50 clinically important human pathogens using 1353 gene-expression profiles generated from >60 human cells/tissues. These 50 pathogens were further partitioned into eight robust “HTR communities” (i.e., groups with more consensus internal HTR similarities). These communities showed enrichment in specific infection attributes and differential gene expression patterns. Using query signatures of HTRs to external pathogens, we demonstrated four distinct modes of HTR associations among different pathogens types/class, and validated the reliability of the HTR community divisions for differentiating and categorizing pathogens from a host-oriented perspective. These findings provide a first-generation HTR Connectivity Map of 50 diverse pathogens, and demonstrate the potential for using annotated HTR community to detect functional associations among infectious pathogens. PMID:26508266

  5. Genome-wide non-CpG methylation of the host genome during M. tuberculosis infection

    PubMed Central

    Sharma, Garima; Sowpati, Divya Tej; Singh, Prakruti; Khan, Mehak Zahoor; Ganji, Rakesh; Upadhyay, Sandeep; Banerjee, Sharmistha; Nandicoori, Vinay Kumar; Khosla, Sanjeev

    2016-01-01

    A mammalian cell utilizes DNA methylation to modulate gene expression in response to environmental changes during development and differentiation. Aberrant DNA methylation changes as a correlate to diseased states like cancer, neurodegenerative conditions and cardiovascular diseases have been documented. Here we show genome-wide DNA methylation changes in macrophages infected with the pathogen M. tuberculosis. Majority of the affected genomic loci were hypermethylated in M. tuberculosis infected THP1 macrophages. Hotspots of differential DNA methylation were enriched in genes involved in immune response and chromatin reorganization. Importantly, DNA methylation changes were observed predominantly for cytosines present in non-CpG dinucleotide context. This observation was consistent with our previous finding that the mycobacterial DNA methyltransferase, Rv2966c, targets non-CpG dinucleotides in the host DNA during M. tuberculosis infection and reiterates the hypothesis that pathogenic bacteria use non-canonical epigenetic strategies during infection. PMID:27112593

  6. Genome-wide non-CpG methylation of the host genome during M. tuberculosis infection.

    PubMed

    Sharma, Garima; Sowpati, Divya Tej; Singh, Prakruti; Khan, Mehak Zahoor; Ganji, Rakesh; Upadhyay, Sandeep; Banerjee, Sharmistha; Nandicoori, Vinay Kumar; Khosla, Sanjeev

    2016-01-01

    A mammalian cell utilizes DNA methylation to modulate gene expression in response to environmental changes during development and differentiation. Aberrant DNA methylation changes as a correlate to diseased states like cancer, neurodegenerative conditions and cardiovascular diseases have been documented. Here we show genome-wide DNA methylation changes in macrophages infected with the pathogen M. tuberculosis. Majority of the affected genomic loci were hypermethylated in M. tuberculosis infected THP1 macrophages. Hotspots of differential DNA methylation were enriched in genes involved in immune response and chromatin reorganization. Importantly, DNA methylation changes were observed predominantly for cytosines present in non-CpG dinucleotide context. This observation was consistent with our previous finding that the mycobacterial DNA methyltransferase, Rv2966c, targets non-CpG dinucleotides in the host DNA during M. tuberculosis infection and reiterates the hypothesis that pathogenic bacteria use non-canonical epigenetic strategies during infection. PMID:27112593

  7. Interactions between Trypanosoma cruzi Secreted Proteins and Host Cell Signaling Pathways

    PubMed Central

    Watanabe Costa, Renata; da Silveira, Jose F.; Bahia, Diana

    2016-01-01

    Chagas disease is one of the prevalent neglected tropical diseases, affecting at least 6–7 million individuals in Latin America. It is caused by the protozoan parasite Trypanosoma cruzi, which is transmitted to vertebrate hosts by blood-sucking insects. After infection, the parasite invades and multiplies in the myocardium, leading to acute myocarditis that kills around 5% of untreated individuals. T. cruzi secretes proteins that manipulate multiple host cell signaling pathways to promote host cell invasion. The primary secreted lysosomal peptidase in T. cruzi is cruzipain, which has been shown to modulate the host immune response. Cruzipain hinders macrophage activation during the early stages of infection by interrupting the NF-kB P65 mediated signaling pathway. This allows the parasite to survive and replicate, and may contribute to the spread of infection in acute Chagas disease. Another secreted protein P21, which is expressed in all of the developmental stages of T. cruzi, has been shown to modulate host phagocytosis signaling pathways. The parasite also secretes soluble factors that exert effects on host extracellular matrix, such as proteolytic degradation of collagens. Finally, secreted phospholipase A from T. cruzi contributes to lipid modifications on host cells and concomitantly activates the PKC signaling pathway. Here, we present a brief review of the interaction between secreted proteins from T. cruzi and the host cells, emphasizing the manipulation of host signaling pathways during invasion. PMID:27065960

  8. Influenza A virus-infected hosts boost an invasive type of Streptococcus pyogenes infection in mice.

    PubMed

    Okamoto, Shigefumi; Kawabata, Shigetada; Nakagawa, Ichiro; Okuno, Yoshinobu; Goto, Toshiyuki; Sano, Kouichi; Hamada, Shigeyuki

    2003-04-01

    The apparent worldwide resurgence of invasive Streptococcus pyogenes infection in the last two decades remains unexplained. At present, animal models in which toxic shock-like syndrome or necrotizing fasciitis is induced after S. pyogenes infection are not well developed. We demonstrate here that infection with a nonlethal dose of influenza A virus 2 days before intranasal infection with a nonlethal dose of S. pyogenes strains led to a death rate of more than 90% in mice, 10% of which showed necrotizing fasciitis. Infection of lung alveolar epithelial cells by the influenza A virus resulted in viral hemagglutinin expression on the cell surface and promoted internalization of S. pyogenes. However, treatment with monoclonal antibodies to hemagglutinin markedly decreased this internalization. Our results indicate that prior infection with influenza A virus induces a lethal synergism, resulting in the induction of invasive S. pyogenes infection in mice.

  9. Host Factors Modulating RSV Infection: Use of Small Interfering RNAs to Probe Functional Importance.

    PubMed

    Caly, Leon; Li, Hong-Mei; Jans, David

    2016-01-01

    Although respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in infants and the elderly worldwide [1], the protein-protein interactions between the host cell and virus remain poorly understood. We have used a focused small interfering RNA (siRNA) approach to knock-down and examine the role(s) of various host cell proteins. Here, we describe approaches for casein kinase 2α (CK2α) as a key example. We show how to study the effect of host gene (CK2α) knockdown using siRNA on cell-associated and released virus titers, using both quantitative RT-PCR, which measures the level of viral RNA, and plaque assay, which measures infectious virus directly. Both assays identified reduced viral titers with CK2α gene knock-down, indicating that it is likely required for efficient viral assembly and/or release. Effects were confirmed in RSV infected cells using the specific CK2α inhibitor 4,5,6,7-tetrabromobenzotriazole, revealing a similar reduction in viral titers as CK2α specific siRNA. This demonstrates that siRNA can be used to characterize critical host cell-RSV protein-protein interactions, and establishes CK2α as a future druggable target. PMID:27464690

  10. Host gene expression for Mycobacterium avium subsp. paratuberculosis infection in human THP-1 macrophages.

    PubMed

    Shin, Min-Kyoung; Shin, Seung Won; Jung, Myunghwan; Park, Hongtae; Park, Hyun-Eui; Yoo, Han Sang

    2015-07-01

    Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, which causes considerable economic loss in the dairy industry and has a possible relationship to Crohn's disease (CD) in humans. As MAP has been detected in retail pasteurized milk samples, its transmission via milk is of concern. Despite its possible role in the etiology of CD, there have been few studies examining the interactions between MAP and human cells. In the current study, we applied Ingenuity Pathway Analysis to the transcription profiles generated from a murine model with MAP infection as part of a previously conducted study. Twenty-one genes were selected as potential host immune responses, compared with the transcriptional profiles in naturally MAP-infected cattle, and validated in MAP-infected human monocyte-derived macrophage THP-1 cells. Of these, the potential host responses included up-regulation of genes related to immune response (CD14, S100A8, S100A9, LTF, HP and CHCIL3), up-regulation of Th1-polarizing factor (CCL4, CCL5, CXCL9 and CXCL10), down-regulation of genes related to metabolism (ELANE, IGF1, TCF7L2 and MPO) and no significant response of other genes (GADD45a, GPNMB, HMOX1, IFNG and NQO1) in THP-1 cells infected with MAP. PMID:25877879

  11. Genomic and functional analysis of the host response to acute simian varicella infection in the lung

    PubMed Central

    Arnold, Nicole; Girke, Thomas; Sureshchandra, Suhas; Nguyen, Christina; Rais, Maham; Messaoudi, Ilhem

    2016-01-01

    Varicella Zoster Virus (VZV) is the causative agent of varicella and herpes zoster. Although it is well established that VZV is transmitted via the respiratory route, the host-pathogen interactions during acute VZV infection in the lungs remain poorly understood due to limited access to clinical samples. To address these gaps in our knowledge, we leveraged a nonhuman primate model of VZV infection where rhesus macaques are intrabronchially challenged with the closely related Simian Varicella Virus (SVV). Acute infection is characterized by immune infiltration of the lung airways, a significant up-regulation of genes involved in antiviral-immunity, and a down-regulation of genes involved in lung development. This is followed by a decrease in viral loads and increased expression of genes associated with cell cycle and tissue repair. These data provide the first characterization of the host response required to control varicella virus replication in the lung and provide insight into mechanisms by which VZV infection can cause lung injury in an immune competent host. PMID:27677639

  12. The Influenza Virus H5N1 Infection Can Induce ROS Production for Viral Replication and Host Cell Death in A549 Cells Modulated by Human Cu/Zn Superoxide Dismutase (SOD1) Overexpression

    PubMed Central

    Lin, Xian; Wang, Ruifang; Zou, Wei; Sun, Xin; Liu, Xiaokun; Zhao, Lianzhong; Wang, Shengyu; Jin, Meilin

    2016-01-01

    Highly pathogenic H5N1 infections are often accompanied by excessive pro-inflammatory response, high viral titer, and apoptosis; as such, the efficient control of these infections poses a great challenge. The pathogenesis of influenza virus infection is also related to oxidative stress. However, the role of endogenic genes with antioxidant effect in the control of influenza viruses, especially H5N1 viruses, should be further investigated. In this study, the H5N1 infection in lung epithelial cells decreased Cu/Zn superoxide dismutase (SOD1) expression at mRNA and protein levels. Forced SOD1 expression significantly inhibited the H5N1-induced increase in reactive oxygen species, decreased pro-inflammatory response, prevented p65 and p38 phosphorylation, and impeded viral ribonucleoprotein nuclear export and viral replication. The SOD1 overexpression also rescued H5N1-induced cellular apoptosis and alleviated H5N1-caused mitochondrial dysfunction. Therefore, this study described the role of SOD1 in the replication of H5N1 influenza virus and emphasized the relevance of this enzyme in the control of H5N1 replication in epithelial cells. Pharmacological modulation or targeting SOD1 may open a new way to fight H5N1 influenza virus. PMID:26761025

  13. The Influenza Virus H5N1 Infection Can Induce ROS Production for Viral Replication and Host Cell Death in A549 Cells Modulated by Human Cu/Zn Superoxide Dismutase (SOD1) Overexpression.

    PubMed

    Lin, Xian; Wang, Ruifang; Zou, Wei; Sun, Xin; Liu, Xiaokun; Zhao, Lianzhong; Wang, Shengyu; Jin, Meilin

    2016-01-08

    Highly pathogenic H5N1 infections are often accompanied by excessive pro-inflammatory response, high viral titer, and apoptosis; as such, the efficient control of these infections poses a great challenge. The pathogenesis of influenza virus infection is also related to oxidative stress. However, the role of endogenic genes with antioxidant effect in the control of influenza viruses, especially H5N1 viruses, should be further investigated. In this study, the H5N1 infection in lung epithelial cells decreased Cu/Zn superoxide dismutase (SOD1) expression at mRNA and protein levels. Forced SOD1 expression significantly inhibited the H5N1-induced increase in reactive oxygen species, decreased pro-inflammatory response, prevented p65 and p38 phosphorylation, and impeded viral ribonucleoprotein nuclear export and viral replication. The SOD1 overexpression also rescued H5N1-induced cellular apoptosis and alleviated H5N1-caused mitochondrial dysfunction. Therefore, this study described the role of SOD1 in the replication of H5N1 influenza virus and emphasized the relevance of this enzyme in the control of H5N1 replication in epithelial cells. Pharmacological modulation or targeting SOD1 may open a new way to fight H5N1 influenza virus.

  14. An important role of prostanoid receptor EP2 in host resistance to Mycobacterium tuberculosis infection in mice.

    PubMed

    Kaul, Vandana; Bhattacharya, Debapriya; Singh, Yogesh; Van Kaer, Luc; Peters-Golden, Marc; Bishai, William R; Das, Gobardhan

    2012-12-15

    Mycobacterium tuberculosis, the causative agent of tuberculosis, resides and replicates within susceptible hosts by inhibiting host antimicrobial mechanisms. Prostaglandin E(2) (PGE(2)), produced by M. tuberculosis-infected macrophages, exerts a variety of immunomodulatory functions via 4 receptors (EP1-EP4), each mediating distinct PGE(2) functions. Here, we show that M. tuberculosis infection selectively upregulates EP2 messenger RNA expression in CD4(+) T cells. We found that EP2 deficiency in mice increases susceptibility to M. tuberculosis infection, which correlated with reduced antigen-specific T-cell responses and increased levels of CD4(+)CD25(+)Foxp3(+) T-regulatory cells. These findings have revealed an important role for EP2 in host immune defense against tuberculosis. As a G protein-coupled receptor, EP2 could serve as a target for immunotherapy of tuberculosis.

  15. Interaction of human tumor viruses with host cell surface receptors and cell entry.

    PubMed

    Schäfer, Georgia; Blumenthal, Melissa J; Katz, Arieh A

    2015-05-22

    Currently, seven viruses, namely Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpes virus (KSHV), high-risk human papillomaviruses (HPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV) and human T cell lymphotropic virus type 1 (HTLV-1), have been described to be consistently associated with different types of human cancer. These oncogenic viruses belong to distinct viral families, display diverse cell tropism and cause different malignancies. A key to their pathogenicity is attachment to the host cell and entry in order to replicate and complete their life cycle. Interaction with the host cell during viral entry is characterized by a sequence of events, involving viral envelope and/or capsid molecules as well as cellular entry factors that are critical in target cell recognition, thereby determining cell tropism. Most oncogenic viruses initially attach to cell surface heparan sulfate proteoglycans, followed by conformational change and transfer of the viral particle to secondary high-affinity cell- and virus-specific receptors. This review summarizes the current knowledge of the host cell surface factors and molecular mechanisms underlying oncogenic virus binding and uptake by their cognate host cell(s) with the aim to provide a concise overview of potential target molecules for prevention and/or treatment of oncogenic virus infection.

  16. Interaction of Human Tumor Viruses with Host Cell Surface Receptors and Cell Entry

    PubMed Central

    Schäfer, Georgia; Blumenthal, Melissa J.; Katz, Arieh A.

    2015-01-01

    Currently, seven viruses, namely Epstein-Barr virus (EBV), Kaposi’s sarcoma-associated herpes virus (KSHV), high-risk human papillomaviruses (HPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV) and human T cell lymphotropic virus type 1 (HTLV-1), have been described to be consistently associated with different types of human cancer. These oncogenic viruses belong to distinct viral families, display diverse cell tropism and cause different malignancies. A key to their pathogenicity is attachment to the host cell and entry in order to replicate and complete their life cycle. Interaction with the host cell during viral entry is characterized by a sequence of events, involving viral envelope and/or capsid molecules as well as cellular entry factors that are critical in target cell recognition, thereby determining cell tropism. Most oncogenic viruses initially attach to cell surface heparan sulfate proteoglycans, followed by conformational change and transfer of the viral particle to secondary high-affinity cell- and virus-specific receptors. This review summarizes the current knowledge of the host cell surface factors and molecular mechanisms underlying oncogenic virus binding and uptake by their cognate host cell(s) with the aim to provide a concise overview of potential target molecules for prevention and/or treatment of oncogenic virus infection. PMID:26008702

  17. Susceptibility of avian hosts to experimental Gymnophalloides seoi infection.

    PubMed

    Ryang, Y S; Yoo, J C; Lee, S H; Chai, J Y

    2001-04-01

    To determine whether avian species are susceptible to infection with Gymnophalloides seoi (a human-infecting intestinal trematode), we exposed 7 species of birds with metacercariae obtained from oysters. The birds were necropsied at days 2, 4, and 6 postinfection (PI). The highest worm recovery at day 6 PI was obtained from the Kentish plover (Charadrius alexandrinus; mean = 56.0%), followed by the Mongolian plover (C. mongolus; 49.3%), and the grey plover (Pluvialis squatarola; 32.3%). In contrast, no mature worms were recovered from the great knot (Calidris tenuirostris), dunlin (C. alpina), black-tailed gull (Larus crassirostris), and mallard (Anas platyrhynchos). Among the plovers, the worms attained the greatest size at day 6 PI (254.1 x 190.4 microm) in the Kentish plover, with a significantly higher number of eggs in the uterus. The 3 species of plovers are highly susceptible to experimental G. seoi infection, suggesting that they could play a role as definitive hosts for these worms in nature.

  18. Early Bunyavirus-Host Cell Interactions

    PubMed Central

    Albornoz, Amelina; Hoffmann, Anja B.; Lozach, Pierre-Yves; Tischler, Nicole D.

    2016-01-01

    The Bunyaviridae is the largest family of RNA viruses, with over 350 members worldwide. Several of these viruses cause severe diseases in livestock and humans. With an increasing number and frequency of outbreaks, bunyaviruses represent a growing threat to public health and agricultural productivity globally. Yet, the receptors, cellular factors and endocytic pathways used by these emerging pathogens to infect cells remain largely uncharacterized. The focus of this review is on the early steps of bunyavirus infection, from virus binding to penetration from endosomes. We address current knowledge and advances for members from each genus in the Bunyaviridae family regarding virus receptors, uptake, intracellular trafficking and fusion. PMID:27213430

  19. Early Bunyavirus-Host Cell Interactions.

    PubMed

    Albornoz, Amelina; Hoffmann, Anja B; Lozach, Pierre-Yves; Tischler, Nicole D

    2016-01-01

    The Bunyaviridae is the largest family of RNA viruses, with over 350 members worldwide. Several of these viruses cause severe diseases in livestock and humans. With an increasing number and frequency of outbreaks, bunyaviruses represent a growing threat to public health and agricultural productivity globally. Yet, the receptors, cellular factors and endocytic pathways used by these emerging pathogens to infect cells remain largely uncharacterized. The focus of this review is on the early steps of bunyavirus infection, from virus binding to penetration from endosomes. We address current knowledge and advances for members from each genus in the Bunyaviridae family regarding virus receptors, uptake, intracellular trafficking and fusion. PMID:27213430

  20. Inhibition of host protein synthesis and degradation of cellular mRNAs during infection by influenza and herpes simplex virus

    SciTech Connect

    Inglis, S.C.

    1982-12-01

    Cloned DNA copies of two cellular genes were used to monitor, by blot hybridization, the stability of particular cell mRNAs after infection by influenza virus and herpes virus. The results indicated that the inhibition of host cell protein synthesis that accompanied infection by each virus could be explained by a reduction in the amounts of cellular mRN As in the cytoplasm, and they suggested that this decrease was due to virus-mediated mRNA degradation.

  1. Dissecting host factors that regulate the early stages of tuberculosis infection.

    PubMed

    Agrawal, Neha; Bhattacharyya, Chandrika; Mukherjee, Ankur; Ullah, Ubaid; Pandit, Bhaswati; Rao, Kanury V S; Majumder, Partha P

    2016-09-01

    Incomplete understanding of mechanisms involved in the host-pathogen interactions constrains our efforts to eliminate tuberculosis. In many individuals, resulting from immune response to mycobacterial infection organised structures called granulomas are formed. To identify host responses that may control at least the early stages of infection, we employed an in vitro granuloma model. Here, human PBMCs were infected with live Mycobacterium tuberculosis in culture, and the appearance of granuloma-like structures was monitored over the next several days. Production of cytokines and chemokines in culture supernatants was monitored at various times, and the resulting temporal profiles were examined for possible correlations with either granuloma formation, or bacterial growth. While a positive association of TNF-α and IFN-γ secretion levels with extent of granuloma formation could clearly be identified, we were, however, unable to detect any statistically significant relationship between any cytokine/chemokine and bacterial growth. Examination of specific host cellular biochemical pathways revealed that either modulation of neutral lipid homeostasis through inhibition of the Gi-protein coupled receptor GPR109A, or regulation of host metabolic pathways through addition of vitamin D, provided a more effective means of controlling infection. A subsequent genotypic analysis for a select subset of genes belonging to pathways known to be significant for TB pathology revealed associations of polymorphisms with cytokine secretions and bacterial growth independently. Collectively therefore, the present study supports that key metabolic pathways of the host cell, rather than levels of relevant cytokines/chemokines might be more critical for regulating the intracellular mycobacterial load, in the context of granuloma formation. PMID:27553417

  2. Celecoxib Improves Host Defense through Prostaglandin Inhibition during Histoplasma capsulatum Infection

    PubMed Central

    Pereira, Priscilla Aparecida Tartari; Trindade, Bruno Caetano; Secatto, Adriana; Nicolete, Roberto; Peres-Buzalaf, Camila; Ramos, Simone Gusmão; Sadikot, Ruxana; Bitencourt, Claudia da Silva

    2013-01-01

    Prostaglandins act as mediators of inflammation and, similar to cytokines, function as immune modulators during innate and adaptive immune responses. Therefore, using a pharmacological inhibitor, celecoxib, we investigated the role of prostaglandins in host defense against Histoplasma capsulatum infection in C57BL/6 mice. Our results showed that treatment with celecoxib inhibited cyclooxygenase 2, reduced the total fungal burden, and reduced the concentration of PGE2, cytokines, lymphocytes, neutrophils, and mononuclear cells in the bronchoalveolar space and lung parenchyma. In addition, celecoxib treatment increased the synthesis of nitric oxide, IFN-γ, LTB4, and the phagocytic capacity of alveolar macrophages. Moreover, celecoxib treatment increased the survival of mice after infection with a lethal inoculum of H. capsulatum. These results suggest that prostaglandins alter the host immune response and play an important role in the pathogenesis of histoplasmosis. Thus, the inhibition of prostaglandins could be a valuable immunomodulatory strategy and antifungal therapy for histoplasmosis treatment. PMID:23818746

  3. A novel approach to biocontrol: release of live insect hosts pre-infected with entomopathogenic nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a new application approach, we tested the efficacy of releasing live insect hosts that were pre-infected with entomopathogenic nematodes against insect pests living in cryptic habitats. We hypothesized that the pre-infected hosts could carry the next generation of emerging nematode infective juv...

  4. Release of lipopolysaccharide from intracellular compartments containing Salmonella typhimurium to vesicles of the host epithelial cell.

    PubMed Central

    Garcia-del Portillo, F; Stein, M A; Finlay, B B

    1997-01-01

    The biological effects of bacterial lipopolysaccharide (LPS) on eucaryotic cells have traditionally been characterized following extracellular challenge of LPS on susceptible cells. In this study, we report the capacity of Salmonella typhimurium to release LPS once it is located in the intracellular environment of cultured epithelial cells. LPS is liberated from vacuolar compartments, where intracellular bacteria reside, to vesicles present in the host cell cytosol. The vesicle-associated LPS is detected in infected cells from the time when invading bacteria enter the host cell. Release of LPS is restricted to S. typhimurium-infected cells, with no LPS observed in neighboring uninfected cells, suggesting that dissemination of LPS occurs entirely within the intracellular environment of the infected cell. The amount of LPS present in host vesicles reaches a maximum when intracellular S. typhimurium cells start to proliferate, a time at which the entire host cell cytosol is filled with numerous vesicles containing LPS. All these data support the concept that intracellular bacterial pathogens might signal the host cell from intracellular locations by releasing bioactive bacterial components such as LPS. PMID:8975888

  5. Transcriptional analysis of host responses to Marek's disease virus infection in chicken thymus.

    PubMed

    Hu, Xuming; Qin, Aijian; Xu, Wencai; Wu, Genghua; Li, Dan; Qian, Kun; Shao, Hongxia; Ye, Jianqiang

    2015-01-01

    Marek's disease virus (MDV) is a cell-associated alpha-herpesvirus that causes T-cell lymphomas and nervous disorders in chickens. Different from other lymphoid organs, the thymus is the site of T-cell maturation and differentiation. However, the transcriptional response to MDV infection in the chicken thymus is still not known. In this study, we performed genome-wide expression analysis in thymus tissues of RB1B-infected chickens at different time points to investigate the molecular mechanisms of MDV pathogenesis. The number of differentially expressed genes with 2-fold or higher changes (>2) are as follows: 1,250 genes (7 dpi), 834 genes (14 dpi), 1,958 genes (21 dpi), and 2,306 genes (28 dpi). Gene ontology enrichment analysis revealed that the upregulated genes were involved in immune and inflammatory response at 7 dpi; angiogenesis, cytoskeleton organization, cell adhesion, and signal transduction showed different expressions at 21 and 28 dpi. The expression pattern of 18 randomly selected genes was confirmed by real-time RT-PCR. Several differently expressed host genes associated with tumor development are discussed. We identified the global host-gene expression pattern in the thymus of chickens that responded to MDV infection. The present data may provide groundwork for future investigation in the biology and pathogenesis of MDV.

  6. The presence of host-derived HLA-DR1 on human immunodeficiency virus type 1 increases viral infectivity.

    PubMed Central

    Cantin, R; Fortin, J F; Lamontagne, G; Tremblay, M

    1997-01-01

    Human immunodeficiency virus type 1 (HIV-1) incorporates several host cell components when budding out of the infected cell. One of the most abundant host-derived molecules acquired by HIV-1 is the HLA-DR determinant of the major histocompatibility complex class II (MHC-II) molecules. The fact that CD4 is the natural ligand of MHC-II prompted us to determine if such virally embedded cellular components can affect the biology of the virus. Herein, we report for the first time that the incorporation of cellular HLA-DR1 within HIV-1 enhances its infectivity. This observation was made possible with virions bearing or not bearing on their surfaces host-derived HLA-DR1 glycoproteins. Such virus stocks were prepared by a transient-expression system based on transfection of 293T cells with a recombinant luciferase-encoding HIV-1 molecular clone along with plasmids encoding the alpha and beta chains of HLA-DR1. Cell-free virions recovered from transfected cells were shown to have efficiently incorporated host-derived HLA-DR1 glycoproteins. Infectivity was increased by a factor of 1.6 to 2.3 for virions bearing on their surfaces host-derived HLA-DR1. The observed enhancement of HIV-1 infectivity was independent of the virus stocks used and was seen in several T-lymphoid cell lines, in a premonocytoid cell line, and in primary peripheral blood mononuclear cells. Finally, we determined that the presence of virion-bound cellular HLA-DR1 is associated with faster kinetics of virus infection. Taken together, these results suggest that HLA-DR-1-bearing HIV-1 particles had a greater infectivity per picogram of viral p24 protein than HLA-DR1-free virions. PMID:9032323

  7. Suicide for survival--death of infected erythrocytes as a host mechanism to survive malaria.

    PubMed

    Föller, Michael; Bobbala, Diwakar; Koka, Saisudha; Huber, Stephan M; Gulbins, Erich; Lang, Florian

    2009-01-01

    The pathogen of malaria, Plasmodium, enters erythrocytes and thus escapes recognition by the immune system. The pathogen induces oxidative stress to the host erythrocyte, which triggers eryptosis, the suicidal death of erythrocytes. Eryptosis is characterized by cell shrinkage, membrane blebbing and cell membrane phospholipid scrambling with phosphatidylserine exposure at the cell surface. Phosphatidylserine-exposing erythrocytes are identified by macrophages which engulf and degrade the eryptotic cells. To the extent that infected erythrocytes undergo eryptosis prior to exit of Plasmodiaand subsequent infection of other erythrocytes, the premature eryptosis may protect against malaria. Accordingly, any therapeutical intervention accelerating suicidal death of infected erythrocytes has the potential to foster elimination of infected erythrocytes, delay the development of parasitemia and favorably influence the course of malaria. Eryptosis is stimulated by a wide variety of triggers including osmotic shock, oxidative stress, energy depletion and a wide variety of xenobiotics. Diseases associated with accelerated eryptosis include sepsis, haemolytic uremic syndrome, malaria, sickle-cell anemia, beta-thalassemia, glucose-6-phosphate dehydrogenase (G6PD)-deficiency, phosphate depletion, iron deficiency and Wilson's disease. Among the known stimulators of eryptosis, paclitaxel, chlorpromazine, cyclosporine, curcumin, PGE2 and lead have indeed been shown to favourably influence the course of malaria. Moreover, sickle-cell trait, beta-thalassemia trait, glucose-6-phosphate dehydrogenase (G6PD)-deficiency and iron deficiency confer some protection against a severe course of malaria. Importantly, counteracting Plasmodia by inducing eryptosis is not expected to generate resistance of the pathogen, as the proteins involved in suicidal death of the host cell are not encoded by the pathogen and thus cannot be modified by mutations of its genes.

  8. Effect of parasitic infection on dopamine biosynthesis in dopaminergic cells

    PubMed Central

    Martin, H.L.; Alsaady, I.; Howell, G.; Prandovszky, E.; Peers, C.; Robinson, P.; McConkey, G.A.

    2015-01-01

    Infection by the neurotropic agent Toxoplasma gondii alters rodent behavior and can result in neuropsychiatric symptoms in humans. Little is understood regarding the effects of infection on host neural processes but alterations to dopaminergic neurotransmission are implicated. We have previously reported elevated levels of dopamine (DA) in infected dopaminergic cells however the involvement of the host enzymes and fate of the produced DA were not defined. In order to clarify the effects of infection on host DA biosynthetic enzymes and DA packaging we examined enzyme levels and activity and DA accumulation and release in T. gondii-infected neurosecretory cells. Although the levels of the host tyrosine hydroxylase (TH) and DOPA decarboxylase and AADC (DDC) did not change significantly in infected cultures, DDC was found within the parasitophorous vacuole (PV), the vacuolar compartment where the parasites reside, as well as in the host cytosol in infected dopaminergic cells. Strikingly, DDC was found within the intracellular parasite cysts in infected brain tissue. This finding could provide some explanation for observations of DA within tissue cysts in infected brain as a parasite-encoded enzyme with TH activity was also localized within tissue cysts. In contrast, cellular DA packaging appeared unchanged in single-cell microamperometry experiments and only a fraction of the increased DA was accessible to high potassium-induced release. This study provides some understanding of how this parasite produces elevated DA within dopaminergic cells without the toxic ramifications of free cytosolic DA. The mechanism for synthesis and packaging of DA by T. gondii-infected dopaminergic cells may have important implications for the effects of chronic T. gondii infection on humans and animals. PMID:26297895

  9. Differential evolution of eastern equine encephalitis virus populations in response to host cell type.

    PubMed Central

    Cooper, L A; Scott, T W

    2001-01-01

    Arthropod-borne viruses (arboviruses) cycle between hosts in two widely separated taxonomic groups, vertebrate amplifying hosts and invertebrate vectors, both of which may separately or in concert shape the course of arbovirus evolution. To elucidate the selective pressures associated with virus replication within each portion of this two-host life cycle, the effects of host type on the growth characteristics of the New World alphavirus, eastern equine encephalitis (EEE) virus, were investigated. Multiple lineages of an ancestral EEE virus stock were repeatedly transferred through either mosquito or avian cells or in alternating passages between these two cell types. When assayed in both cell types, derived single host lineages exhibited significant differences in infectivity, growth pattern, plaque morphology, and total virus yield, demonstrating that this virus is capable of host-specific evolution. Virus lineages grown in alternation between the two cell types expressed intermediate phenotypes consistent with dual adaptation to both cellular environments. Both insect-adapted and alternated lineages greatly increased in their ability to infect insect cells. These results indicate that different selective pressures exist for virus replication within each portion of the two-host life cycle, and that alternation of hosts selects for virus populations well adapted for replication in both host systems. PMID:11290699

  10. Genetic Markers of the Host in Persons Living with HTLV-1, HIV and HCV Infections

    PubMed Central

    Assone, Tatiane; Paiva, Arthur; Fonseca, Luiz Augusto M.; Casseb, Jorge

    2016-01-01

    Human T-cell leukemia virus type 1 (HTLV-1), hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) are prevalent worldwide, and share similar means of transmission. These infections may influence each other in evolution and outcome, including cancer or immunodeficiency. Many studies have reported the influence of genetic markers on the host immune response against different persistent viral infections, such as HTLV-1 infection, pointing to the importance of the individual genetic background on their outcomes. However, despite recent advances on the knowledge of the pathogenesis of HTLV-1 infection, gaps in the understanding of the role of the individual genetic background on the progress to disease clinically manifested still remain. In this scenario, much less is known regarding the influence of genetic factors in the context of dual or triple infections or their influence on the underlying mechanisms that lead to outcomes that differ from those observed in monoinfection. This review describes the main factors involved in the virus–host balance, especially for some particular human leukocyte antigen (HLA) haplotypes, and other important genetic markers in the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other persistent viruses, such as HIV and HCV. PMID:26848682

  11. Dynamics of the microbiota in response to host infection.

    PubMed

    Belzer, Clara; Gerber, Georg K; Roeselers, Guus; Delaney, Mary; DuBois, Andrea; Liu, Qing; Belavusava, Vera; Yeliseyev, Vladimir; Houseman, Andres; Onderdonk, Andrew; Cavanaugh, Colleen; Bry, Lynn

    2014-01-01

    Longitudinal studies of the microbiota are important for discovering changes in microbial communities that affect the host. The complexity of these ecosystems requires rigorous integrated experimental and computational methods to identify temporal signatures that promote physiologic or pathophysiologic responses in vivo. Employing a murine model of infectious colitis with the pathogen Citrobacter rodentium, we generated a 2-month time-series of 16S rDNA gene profiles, and quantitatively cultured commensals, from multiple intestinal sites in infected and uninfected mice. We developed a computational framework to discover time-varying signatures for individual taxa, and to automatically group signatures to identify microbial sub-communities within the larger gut ecosystem that demonstrate common behaviors. Application of this model to the 16S rDNA dataset revealed dynamic alterations in the microbiota at multiple levels of resolution, from effects on systems-level metrics to changes across anatomic sites for individual taxa and species. These analyses revealed unique, time-dependent microbial signatures associated with host responses at different stages of colitis. Signatures included a Mucispirillum OTU associated with early disruption of the colonic surface mucus layer, prior to the onset of symptomatic colitis, and members of the Clostridiales and Lactobacillales that increased with successful resolution of inflammation, after clearance of the pathogen. Quantitative culture data validated findings for predominant species, further refining and strengthening model predictions. These findings provide new insights into the complex behaviors found within host ecosystems, and define several time-dependent microbial signatures that may be leveraged in studies of other infectious or inflammatory conditions. PMID:25014551

  12. Lytic infection of Lactococcus lactis by bacteriophages Tuc2009 and c2 triggers alternative transcriptional host responses.

    PubMed

    Ainsworth, Stuart; Zomer, Aldert; Mahony, Jennifer; van Sinderen, Douwe

    2013-08-01

    Here we present an entire temporal transcriptional profile of Lactococcus lactis subsp. cremoris UC509.9 undergoing lytic infection with two distinct bacteriophages, Tuc2009 and c2. Furthermore, corresponding high-resolution whole-phage genome tiling arrays of both bacteriophages were performed throughout lytic infection. Whole-genome microarrays performed at various time points postinfection demonstrated a rather modest impact on host transcription. The majority of changes in the host transcriptome occur during late infection stages; few changes in host gene transcription occur during the immediate and early infection stages. Alterations in the L. lactis UC509.9 transcriptome during lytic infection appear to be phage specific, with relatively few differentially transcribed genes shared between cells infected with Tuc2009 and those infected with c2. Despite the apparent lack of a coordinated general phage response, three themes common to both infections were noted: alternative transcription of genes involved in catabolic flux and energy production, differential transcription of genes involved in cell wall modification, and differential transcription of genes involved in the conversion of ribonucleotides to deoxyribonucleotides. The transcriptional profiles of both bacteriophages during lytic infection generally correlated with the findings of previous studies and allowed the confirmation of previously predicted promoter sequences. In addition, the host transcriptional response to lysogenization with Tuc2009 was monitored along with tiling array analysis of Tuc2009 in the lysogenic state. Analysis identified 44 host genes with altered transcription during lysogeny, 36 of which displayed levels of transcription significantly reduced from those for uninfected cells. PMID:23728817

  13. Lytic Infection of Lactococcus lactis by Bacteriophages Tuc2009 and c2 Triggers Alternative Transcriptional Host Responses

    PubMed Central

    Ainsworth, Stuart; Zomer, Aldert; Mahony, Jennifer

    2013-01-01

    Here we present an entire temporal transcriptional profile of Lactococcus lactis subsp. cremoris UC509.9 undergoing lytic infection with two distinct bacteriophages, Tuc2009 and c2. Furthermore, corresponding high-resolution whole-phage genome tiling arrays of both bacteriophages were performed throughout lytic infection. Whole-genome microarrays performed at various time points postinfection demonstrated a rather modest impact on host transcription. The majority of changes in the host transcriptome occur during late infection stages; few changes in host gene transcription occur during the immediate and early infection stages. Alterations in the L. lactis UC509.9 transcriptome during lytic infection appear to be phage specific, with relatively few differentially transcribed genes shared between cells infected with Tuc2009 and those infected with c2. Despite the apparent lack of a coordinated general phage response, three themes common to both infections were noted: alternative transcription of genes involved in catabolic flux and energy production, differential transcription of genes involved in cell wall modification, and differential transcription of genes involved in the conversion of ribonucleotides to deoxyribonucleotides. The transcriptional profiles of both bacteriophages during lytic infection generally correlated with the findings of previous studies and allowed the confirmation of previously predicted promoter sequences. In addition, the host transcriptional response to lysogenization with Tuc2009 was monitored along with tiling array analysis of Tuc2009 in the lysogenic state. Analysis identified 44 host genes with altered transcription during lysogeny, 36 of which displayed levels of transcription significantly reduced from those for uninfected cells. PMID:23728817

  14. Counting Legionella cells within single amoeba host cells

    EPA Science Inventory

    Here we present the first attempt to quantify L. pneumophila cell numbers within individual amoebae hosts that may be released into engineered water systems. The maximum numbers of culturable L. pneumophila cells grown within Acanthamoeba polyphaga and Naegleria fowleri were 134...

  15. Counting Legionella cells within single amoeba host cells.

    PubMed

    Buse, Helen Y; Ashbolt, Nicholas J

    2012-03-01

    Here we present the first attempt to quantify Legionella pneumophila cell numbers within individual amoeba hosts that may be released into engineered water systems. The maximum numbers of culturable L. pneumophila cells grown within Acanthamoeba polyphaga and Naegleria fowleri were 1,348 (mean, 329) and 385 (mean, 44) CFU trophozoite(-1), respectively.

  16. Species diversity reduces parasite infection through cross-generational effects on host abundance.

    PubMed

    Johnson, Pieter T J; Preston, Daniel L; Hoverman, Jason T; Henderson, Jeremy S; Paull, Sara H; Richgels, Katherine L D; Redmond, Miranda D

    2012-01-01

    With growing interest in the effects of biodiversity on disease, there is a critical need for studies that empirically identify the mechanisms underlying the diversity-disease relationship. Here, we combined wetland surveys of host community structure with mechanistic experiments involving a multi-host parasite to evaluate competing explanations for the dilution effect. Sampling of 320 wetlands in California indicated that snail host communities were strongly nested, with competent hosts for the trematode Ribeiroia ondatrae predominating in low-richness assemblages and unsuitable hosts increasingly present in more diverse communities. Moreover, competent host density was negatively associated with increases in snail species richness. These patterns in host community assembly support a key prerequisite underlying the dilution effect. Results of multigenerational mesocosm experiments designed to mimic field-observed community assemblages allowed us to evaluate the relative importance of host density and diversity in influencing parasite infection success. Increases in snail species richness (from one to four species) had sharply negative effects on the density of infected hosts (-90% reduction). However, this effect was indirect; competition associated with non-host species led to a 95% reduction in host density (susceptible host regulation), owing primarily to a reduction in host reproduction. Among susceptible hosts, there were no differences in infection prevalence as a function of community structure, indicating a lack of support for a direct effect of diversity on infection (encounter reduction). In monospecific conditions, higher initial host densities increased infection among adult hosts; however, compensatory reproduction in the low-density treatments equalized the final number of infected hosts by the next generation, underscoring the relevance of multigenerational studies in understanding the dilution effect. These findings highlight the role of

  17. Intrapopulational distribution of Meiogymnophallus minutus (Digenea, Gymnophallidae) infections in its first and second intermediate host.

    PubMed

    Fermer, Jan; Culloty, Sarah C; Kelly, Thomas C; O'Riordan, Ruth M

    2009-10-01

    Host size and age are generally assumed to play a pivotal role in digenean trematode infection patterns, accounting for much of the variation found within intermediate host populations. However, knowledge is based on a limited number of studied host-parasite systems. We investigated the shell length class distribution of Meiogymnophallus minutus infections within populations of the first intermediate host Scrobicularia plana and second intermediate host Cerastoderma edule. Infections occurred very early in the life of the two intermediate hosts. Both prevalence and intensity of infections increased with host shell length and displayed extremely high values amongst large individuals. Whilst metacercarial infection patterns in juvenile C. edule could be best explained by differences in host shell length, in adult cockles, the effect of host age on infection levels prevailed. The microsporidian hyperparasite Unikaryon legeri, occurring in the metacercarial stage of M. minutus, was particularly abundant in aged cockles, strongly influencing infection patterns of the gymnophallid. Our results are consistent with the intrapopulational distribution reported from other digenean trematode parasites. The relative influence of both host size and age and the underlying mechanisms as well as the impact of hyperparasitism on M. minutus infection patterns are discussed. PMID:19575218

  18. Intrapopulational distribution of Meiogymnophallus minutus (Digenea, Gymnophallidae) infections in its first and second intermediate host.

    PubMed

    Fermer, Jan; Culloty, Sarah C; Kelly, Thomas C; O'Riordan, Ruth M

    2009-10-01

    Host size and age are generally assumed to play a pivotal role in digenean trematode infection patterns, accounting for much of the variation found within intermediate host populations. However, knowledge is based on a limited number of studied host-parasite systems. We investigated the shell length class distribution of Meiogymnophallus minutus infections within populations of the first intermediate host Scrobicularia plana and second intermediate host Cerastoderma edule. Infections occurred very early in the life of the two intermediate hosts. Both prevalence and intensity of infections increased with host shell length and displayed extremely high values amongst large individuals. Whilst metacercarial infection patterns in juvenile C. edule could be best explained by differences in host shell length, in adult cockles, the effect of host age on infection levels prevailed. The microsporidian hyperparasite Unikaryon legeri, occurring in the metacercarial stage of M. minutus, was particularly abundant in aged cockles, strongly influencing infection patterns of the gymnophallid. Our results are consistent with the intrapopulational distribution reported from other digenean trematode parasites. The relative influence of both host size and age and the underlying mechanisms as well as the impact of hyperparasitism on M. minutus infection patterns are discussed.

  19. Severe Babesia microti Infection in an Immunocompetent Host in Pennsylvania.

    PubMed

    Genda, Jeffrey; Negron, Elizabeth A; Lotfipour, Mona; Balabhadra, Samyuktha; Desai, Diana S; Craft, David W; Katzman, Michael

    2016-01-01

    Babesiosis, due to infection by a tick-borne protozoan (predominantly Babesia microti in North America), is an emerging health risk that is expanding into new areas and may be unfamiliar to clinicians in locations not previously considered endemic. Manifestations of infection can range from asymptomatic to life threatening, with severe disease more likely in those who have had a splenectomy, are immunocompromised, have chronic medical conditions, or are over 50 years of age. In this article, we describe an elderly but otherwise healthy man from an area not generally considered endemic for babesiosis who presented with severe hemolysis, acute renal failure, and high-level Babesia microti parasitemia; serological results suggestive of possible coinfection by Borrelia burgdorferi (the agent of Lyme disease, which is carried by the same tick as is Babesia microti) also was found. This report highlights that severe babesiosis can occur in an apparently normal host and underscores the continued geographic expansion of this pathogen and the need for early recognition and therapy. PMID:27656660

  20. Grapevine Pathogenic Microorganisms: Understanding Infection Strategies and Host Response Scenarios.

    PubMed

    Armijo, Grace; Schlechter, Rudolf; Agurto, Mario; Muñoz, Daniela; Nuñez, Constanza; Arce-Johnson, Patricio

    2016-01-01

    Grapevine (Vitis vinifera L.) is one of the most important fruit crop worldwide. Commercial cultivars are greatly affected by a large number of pathogenic microorganisms that cause diseases during pre- and/or post-harvest periods, affecting production, processing and export, along with fruit quality. Among the potential threats, we can find bacteria, fungi, oomycete, or viruses with different life cycles, infection mechanisms and evasion strategies. While plant-pathogen interactions are cycles of resistance and susceptibility, resistance traits from natural resources are selected and may be used for breeding purposes and for a sustainable agriculture. In this context, here we summarize some of the most important diseases affecting V. vinifera together with their causal agents. The aim of this work is to bring a comprehensive review of the infection strategies deployed by significant types of pathogens while understanding the host response in both resistance and susceptibility scenarios. New approaches being used to uncover grapevine status during biotic stresses and scientific-based procedures needed to control plant diseases and crop protection are also addressed.

  1. Grapevine Pathogenic Microorganisms: Understanding Infection Strategies and Host Response Scenarios.

    PubMed

    Armijo, Grace; Schlechter, Rudolf; Agurto, Mario; Muñoz, Daniela; Nuñez, Constanza; Arce-Johnson, Patricio

    2016-01-01

    Grapevine (Vitis vinifera L.) is one of the most important fruit crop worldwide. Commercial cultivars are greatly affected by a large number of pathogenic microorganisms that cause diseases during pre- and/or post-harvest periods, affecting production, processing and export, along with fruit quality. Among the potential threats, we can find bacteria, fungi, oomycete, or viruses with different life cycles, infection mechanisms and evasion strategies. While plant-pathogen interactions are cycles of resistance and susceptibility, resistance traits from natural resources are selected and may be used for breeding purposes and for a sustainable agriculture. In this context, here we summarize some of the most important diseases affecting V. vinifera together with their causal agents. The aim of this work is to bring a comprehensive review of the infection strategies deployed by significant types of pathogens while understanding the host response in both resistance and susceptibility scenarios. New approaches being used to uncover grapevine status during biotic stresses and scientific-based procedures needed to control plant diseases and crop protection are also addressed. PMID:27066032

  2. Severe Babesia microti Infection in an Immunocompetent Host in Pennsylvania

    PubMed Central

    Genda, Jeffrey; Negron, Elizabeth A.; Lotfipour, Mona; Balabhadra, Samyuktha; Desai, Diana S.; Craft, David W.; Katzman, Michael

    2016-01-01

    Babesiosis, due to infection by a tick-borne protozoan (predominantly Babesia microti in North America), is an emerging health risk that is expanding into new areas and may be unfamiliar to clinicians in locations not previously considered endemic. Manifestations of infection can range from asymptomatic to life threatening, with severe disease more likely in those who have had a splenectomy, are immunocompromised, have chronic medical conditions, or are over 50 years of age. In this article, we describe an elderly but otherwise healthy man from an area not generally considered endemic for babesiosis who presented with severe hemolysis, acute renal failure, and high-level Babesia microti parasitemia; serological results suggestive of possible coinfection by Borrelia burgdorferi (the agent of Lyme disease, which is carried by the same tick as is Babesia microti) also was found. This report highlights that severe babesiosis can occur in an apparently normal host and underscores the continued geographic expansion of this pathogen and the need for early recognition and therapy.

  3. Severe Babesia microti Infection in an Immunocompetent Host in Pennsylvania

    PubMed Central

    Genda, Jeffrey; Negron, Elizabeth A.; Lotfipour, Mona; Balabhadra, Samyuktha; Desai, Diana S.; Craft, David W.; Katzman, Michael

    2016-01-01

    Babesiosis, due to infection by a tick-borne protozoan (predominantly Babesia microti in North America), is an emerging health risk that is expanding into new areas and may be unfamiliar to clinicians in locations not previously considered endemic. Manifestations of infection can range from asymptomatic to life threatening, with severe disease more likely in those who have had a splenectomy, are immunocompromised, have chronic medical conditions, or are over 50 years of age. In this article, we describe an elderly but otherwise healthy man from an area not generally considered endemic for babesiosis who presented with severe hemolysis, acute renal failure, and high-level Babesia microti parasitemia; serological results suggestive of possible coinfection by Borrelia burgdorferi (the agent of Lyme disease, which is carried by the same tick as is Babesia microti) also was found. This report highlights that severe babesiosis can occur in an apparently normal host and underscores the continued geographic expansion of this pathogen and the need for early recognition and therapy. PMID:27656660

  4. Grapevine Pathogenic Microorganisms: Understanding Infection Strategies and Host Response Scenarios

    PubMed Central

    Armijo, Grace; Schlechter, Rudolf; Agurto, Mario; Muñoz, Daniela; Nuñez, Constanza; Arce-Johnson, Patricio

    2016-01-01

    Grapevine (Vitis vinifera L.) is one of the most important fruit crop worldwide. Commercial cultivars are greatly affected by a large number of pathogenic microorganisms that cause diseases during pre- and/or post-harvest periods, affecting production, processing and export, along with fruit quality. Among the potential threats, we can find bacteria, fungi, oomycete, or viruses with different life cycles, infection mechanisms and evasion strategies. While plant–pathogen interactions are cycles of resistance and susceptibility, resistance traits from natural resources are selected and may be used for breeding purposes and for a sustainable agriculture. In this context, here we summarize some of the most important diseases affecting V. vinifera together with their causal agents. The aim of this work is to bring a comprehensive review of the infection strategies deployed by significant types of pathogens while understanding the host response in both resistance and susceptibility scenarios. New approaches being used to uncover grapevine status during biotic stresses and scientific-based procedures needed to control plant diseases and crop protection are also addressed. PMID:27066032

  5. Cellular responses to HSV-1 infection are linked to specific types of alterations in the host transcriptome

    PubMed Central

    Hu, Benxia; Li, Xin; Huo, Yongxia; Yu, Yafen; Zhang, Qiuping; Chen, Guijun; Zhang, Yaping; Fraser, Nigel W.; Wu, Dongdong; Zhou, Jumin

    2016-01-01

    Pathogen invasion triggers a number of cellular responses and alters the host transcriptome. Here we report that the type of changes to cellular transcriptome is related to the type of cellular functions affected by lytic infection of Herpes Simplex Virus type I in Human primary fibroblasts. Specifically, genes involved in stress responses and nuclear transport exhibited mostly changes in alternative polyadenylation (APA), cell cycle genes showed mostly alternative splicing (AS) changes, while genes in neurogenesis, rarely underwent these changes. Transcriptome wide, the infection resulted in 1,032 cases of AS, 161 incidences of APA, 1,827 events of isoform changes, and up regulation of 596 genes and down regulations of 61 genes compared to uninfected cells. Thus, these findings provided important and specific links between cellular responses to HSV-1 infection and the type of alterations to the host transcriptome, highlighting important roles of RNA processing in virus-host interactions. PMID:27354008

  6. Cellular responses to HSV-1 infection are linked to specific types of alterations in the host transcriptome.

    PubMed

    Hu, Benxia; Li, Xin; Huo, Yongxia; Yu, Yafen; Zhang, Qiuping; Chen, Guijun; Zhang, Yaping; Fraser, Nigel W; Wu, Dongdong; Zhou, Jumin

    2016-01-01

    Pathogen invasion triggers a number of cellular responses and alters the host transcriptome. Here we report that the type of changes to cellular transcriptome is related to the type of cellular functions affected by lytic infection of Herpes Simplex Virus type I in Human primary fibroblasts. Specifically, genes involved in stress responses and nuclear transport exhibited mostly changes in alternative polyadenylation (APA), cell cycle genes showed mostly alternative splicing (AS) changes, while genes in neurogenesis, rarely underwent these changes. Transcriptome wide, the infection resulted in 1,032 cases of AS, 161 incidences of APA, 1,827 events of isoform changes, and up regulation of 596 genes and down regulations of 61 genes compared to uninfected cells. Thus, these findings provided important and specific links between cellular responses to HSV-1 infection and the type of alterations to the host transcriptome, highlighting important roles of RNA processing in virus-host interactions. PMID:27354008

  7. 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. PMID:25982695

  8. The cell biology of Cryptosporidium infection

    PubMed Central

    O’Hara, Steven P.; Chen, Xian-Ming

    2011-01-01

    Cryptosporidiosis remains a significant cause of enteric disease worldwide. Basic investigations of host: pathogen interactions have revealed the intricate processes mediating infection. The following summarizes the interactions that mediate infection and the host responses that both permit and ultimately clear the infection. PMID:21458585

  9. The role of NOD1 and NOD2 in host defense against chlamydial infection.

    PubMed

    Zou, Yan; Lei, Wenbo; He, Zhansheng; Li, Zhongyu

    2016-09-01

    Chlamydial species are common intracellular parasites that cause various diseases, mainly characterized by persistent infection, which lead to inflammatory responses modulated by pattern recognition receptors (PRRs). The best understood PRRs are the extracellular Toll-like receptors, but recent significant advances have focused on two important proteins, NOD1 and NOD2, which are members of the intracellular nucleotide-binding oligomerization domain receptor family and are capable of triggering the host innate immune signaling pathways. This results in the production of pro-inflammatory cytokines, which is vital for an adequate host defense against intracellular chlamydial infection. NOD1/2 ligands are known to derive from peptidoglycan, and the latest research has resolved the paradox of whether chlamydial species possess this bacterial cell wall component; this finding is likely to promote in-depth investigations into the interaction between the NOD proteins and chlamydial pathogens. In this review, we summarize the basic characteristics and signal transduction functions of NOD1 and NOD2 and highlight the new research on the roles of NOD1 and NOD2 in the host defense against chlamydial infection.

  10. Visualizing the structural changes of bacteriophage Epsilon15 and its Salmonella host during infection.

    PubMed

    Chang, Juan T; Schmid, Michael F; Haase-Pettingell, Cameron; Weigele, Peter R; King, Jonathan A; Chiu, Wah

    2010-10-01

    The efficient mechanism by which double-stranded DNA bacteriophages deliver their chromosome across the outer membrane, cell wall, and inner membrane of Gram-negative bacteria remains obscure. Advances in single-particle electron cryomicroscopy have recently revealed details of the organization of the DNA injection apparatus within the mature virion for various bacteriophages, including epsilon15 (ɛ15) and P-SSP7. We have used electron cryotomography and three-dimensional subvolume averaging to capture snapshots of ɛ15 infecting its host Salmonella anatum. These structures suggest the following stages of infection. In the first stage, the tailspikes of ɛ15 attach to the surface of the host cell. Next, ɛ15's tail hub attaches to a putative cell receptor and establishes a tunnel through which the injection core proteins behind the portal exit the virion. A tube spanning the periplasmic space is formed for viral DNA passage, presumably from the rearrangement of core proteins or from cellular components. This tube would direct the DNA into the cytoplasm and protect it from periplasmic nucleases. Once the DNA has been injected into the cell, the tube and portal seals, and the empty bacteriophage remains at the cell surface.

  11. Host Nectin-1 Promotes Chlamydial Infection in the Female Mouse Genital Tract, but Is Not Required for Infection in a Novel Male Murine Rectal Infection Model.

    PubMed

    Slade, Jessica A; Hall, Jennifer V; Kintner, Jennifer; Phillips-Campbell, Regenia; Schoborg, Robert V

    2016-01-01

    Chlamydia trachomatis is the most common bacterial sexually transmitted pathogen, but more than 70% of patients fail to seek treatment due to the asymptomatic nature of these infections. Women suffer from numerous complications from chronic chlamydial infections, which include pelvic inflammatory disease and infertility. We previously demonstrated in culture that host cell nectin-1 knockdown significantly reduced chlamydial titers and inclusion size. Here, we sought to determine whether nectin-1 was required for chlamydial development in vivo by intravaginally infecting nectin-1-/- mice with Chlamydia muridarum and monitoring chlamydial shedding by chlamydial titer assay. We observed a significant reduction in chlamydial shedding in female nectin-1-/- mice compared to nectin-1+/+ control mice, an observation that was confirmed by PCR. Immunohistochemical staining in mouse cervical tissue confirmed that there are fewer chlamydial inclusions in Chlamydia-infected nectin-1-/- mice. Notably, anorectal chlamydial infections are becoming a substantial health burden, though little is known regarding the pathogenesis of these infections. We therefore established a novel male murine model of rectal chlamydial infection, which we used to determine whether nectin-1 is required for anorectal chlamydial infection in male mice. In contrast to the data from vaginal infection, no difference in rectal chlamydial shedding was observed when male nectin-1+/+ and nectin-1-/- mice were compared. Through the use of these two models, we have demonstrated that nectin-1 promotes chlamydial infection in the female genital tract but does not appear to contribute to rectal infection in male mice. These models could be used to further characterize tissue and sex related differences in chlamydial infection. PMID:27486990

  12. Host Nectin-1 Promotes Chlamydial Infection in the Female Mouse Genital Tract, but Is Not Required for Infection in a Novel Male Murine Rectal Infection Model

    PubMed Central

    Slade, Jessica A.; Hall, Jennifer V.; Kintner, Jennifer; Phillips-Campbell, Regenia; Schoborg, Robert V.

    2016-01-01

    Chlamydia trachomatis is the most common bacterial sexually transmitted pathogen, but more than 70% of patients fail to seek treatment due to the asymptomatic nature of these infections. Women suffer from numerous complications from chronic chlamydial infections, which include pelvic inflammatory disease and infertility. We previously demonstrated in culture that host cell nectin-1 knockdown significantly reduced chlamydial titers and inclusion size. Here, we sought to determine whether nectin-1 was required for chlamydial development in vivo by intravaginally infecting nectin-1-/- mice with Chlamydia muridarum and monitoring chlamydial shedding by chlamydial titer assay. We observed a significant reduction in chlamydial shedding in female nectin-1-/- mice compared to nectin-1+/+ control mice, an observation that was confirmed by PCR. Immunohistochemical staining in mouse cervical tissue confirmed that there are fewer chlamydial inclusions in Chlamydia-infected nectin-1-/- mice. Notably, anorectal chlamydial infections are becoming a substantial health burden, though little is known regarding the pathogenesis of these infections. We therefore established a novel male murine model of rectal chlamydial infection, which we used to determine whether nectin-1 is required for anorectal chlamydial infection in male mice. In contrast to the data from vaginal infection, no difference in rectal chlamydial shedding was observed when male nectin-1+/+ and nectin-1-/- mice were compared. Through the use of these two models, we have demonstrated that nectin-1 promotes chlamydial infection in the female genital tract but does not appear to contribute to rectal infection in male mice. These models could be used to further characterize tissue and sex related differences in chlamydial infection. PMID:27486990

  13. Host species composition influences infection severity among amphibians in the absence of spillover transmission

    PubMed Central

    Han, Barbara A; Kerby, Jacob L; Searle, Catherine L; Storfer, Andrew; Blaustein, Andrew R

    2015-01-01

    Wildlife epidemiological outcomes can depend strongly on the composition of an ecological community, particularly when multiple host species are affected by the same pathogen. However, the relationship between host species richness and disease risk can vary with community context and with the degree of spillover transmission that occurs among co-occurring host species. We examined the degree to which host species composition influences infection by Batrachochytrium dendrobatidis (Bd), a widespread fungal pathogen associated with amphibian population declines around the world, and whether transmission occurs from one highly susceptible host species to other co-occurring host species. By manipulating larval assemblages of three sympatric amphibian species in the laboratory, we characterized the relationship between host species richness and infection severity, whether infection mediates growth and survivorship differently across various combinations of host species, and whether Bd is transmitted from experimentally inoculated tadpoles to uninfected tadpoles. We found evidence of a dilution effect where Bd infection severity was dramatically reduced in the most susceptible of the three host species (Anaxyrus boreas). Infection also mediated survival and growth of all three host species such that the presence of multiple host species had both positive (e.g., infection reduction) and negative (e.g., mortality) effects on focal species. However, we found no evidence that Bd infection is transmitted by this species. While these results demonstrate that host species richness as well as species identity underpin infection dynamics in this system, dilution is not the product of reduced transmission via fewer infectious individuals of a susceptible host species. We discuss various mechanisms, including encounter reduction and antagonistic interactions such as competition and opportunistic cannibalism that may act in concert to mediate patterns of infection severity, growth

  14. Coinfection with Different Trypanosoma cruzi Strains Interferes with the Host Immune Response to Infection

    PubMed Central

    Rodrigues, Claudiney Melquíades; Valadares, Helder Magno Silva; Francisco, Amanda Fortes; Arantes, Jerusa Marilda; Campos, Camila França; Teixeira-Carvalho, Andréa; Martins-Filho, Olindo Assis; Araujo, Márcio Sobreira Silva; Arantes, Rosa Maria Esteves; Chiari, Egler; Franco, Glória Regina; Machado, Carlos Renato; Pena, Sérgio Danilo Junho; Faria, Ana Maria Caetano; Macedo, Andréa Mara

    2010-01-01

    A century after the discovery of Trypanosoma cruzi in a child living in Lassance, Minas Gerais, Brazil in 1909, many uncertainties remain with respect to factors determining the pathogenesis of Chagas disease (CD). Herein, we simultaneously investigate the contribution of both host and parasite factors during acute phase of infection in BALB/c mice infected with the JG and/or CL Brener T. cruzi strains. JG single infected mice presented reduced parasitemia and heart parasitism, no mortality, levels of pro-inflammatory mediators (TNF-α, CCL2, IL-6 and IFN-γ) similar to those found among naïve animals and no clinical manifestations of disease. On the other hand, CL Brener single infected mice presented higher parasitemia and heart parasitism, as well as an increased systemic release of pro-inflammatory mediators and higher mortality probably due to a toxic shock-like systemic inflammatory response. Interestingly, coinfection with JG and CL Brener strains resulted in intermediate parasitemia, heart parasitism and mortality. This was accompanied by an increase in the systemic release of IL-10 with a parallel increase in the number of MAC-3+ and CD4+ T spleen cells expressing IL-10. Therefore, the endogenous production of IL-10 elicited by coinfection seems to be crucial to counterregulate the potentially lethal effects triggered by systemic release of pro-inflammatory mediators induced by CL Brener single infection. In conclusion, our results suggest that the composition of the infecting parasite population plays a role in the host response to T. cruzi in determining the severity of the disease in experimentally infected BALB/c mice. The combination of JG and CL Brener was able to trigger both protective inflammatory immunity and regulatory immune mechanisms that attenuate damage caused by inflammation and disease severity in BALB/c mice. PMID:20967289

  15. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    PubMed

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas.

  16. Cell wall glycoproteins at interaction sites between parasitic giant dodder (Cuscuta reflexa) and its host Pelargonium zonale.

    PubMed

    Striberny, Bernd; Krause, Kirsten

    2015-01-01

    The process of host plant penetration by parasitic dodder (genus Cuscuta) is accompanied by molecular and structural changes at the host/parasite interface. Recently, changes in pectin methyl esterification levels in the host cell walls abutting parasitic cells in established infection sites were reported. In addition to that, we show here that the composition of cell wall glycoproteins in Cuscuta-infected Pelargonium zonale undergoes substantial changes. While several arabinogalactan protein epitopes exhibit decreased abundances in the vicinity of the Cuscuta reflexa haustorium, extensins tend to increase in the infected areas. PMID:26367804

  17. Host Control of Malaria Infections: Constraints on Immune and Erythropoeitic Response Kinetics

    PubMed Central

    McQueen, Philip G.; McKenzie, F. Ellis

    2008-01-01

    The two main agents of human malaria, Plasmodium vivax and Plasmodium falciparum, can induce severe anemia and provoke strong, complex immune reactions. Which dynamical behaviors of host immune and erythropoietic responses would foster control of infection, and which would lead to runaway parasitemia and/or severe anemia? To answer these questions, we developed differential equation models of interacting parasite and red blood cell (RBC) populations modulated by host immune and erythropoietic responses. The model immune responses incorporate both a rapidly responding innate component and a slower-responding, long-term antibody component, with several parasite developmental stages considered as targets for each type of immune response. We found that simulated infections with the highest parasitemia tended to be those with ineffective innate immunity even if antibodies were present. We also compared infections with dyserythropoiesis (reduced RBC production during infection) to those with compensatory erythropoiesis (boosted RBC production) or a fixed basal RBC production rate. Dyserythropoiesis tended to reduce parasitemia slightly but at a cost to the host of aggravating anemia. On the other hand, compensatory erythropoiesis tended to reduce the severity of anemia but with enhanced parasitemia if the innate response was ineffective. For both parasite species, sharp transitions between the schizont and the merozoite stages of development (i.e., with standard deviation in intra-RBC development time ≤2.4 h) were associated with lower parasitemia and less severe anemia. Thus tight synchronization in asexual parasite development might help control parasitemia. Finally, our simulations suggest that P. vivax can induce severe anemia as readily as P. falciparum for the same type of immune response, though P. vivax attacks a much smaller subset of RBCs. Since most P. vivax infections are nonlethal (if debilitating) clinically, this suggests that P. falciparum adaptations

  18. Ovine trophoblasts express cathelicidin host defence peptide in response to infection.

    PubMed

    Coyle, Christopher; Wheelhouse, Nick; Jacques, Maxime; Longbottom, David; Svoboda, Pavel; Pohl, Jan; Duncan, W Colin; Rae, Michael T; Barlow, Peter G

    2016-09-01

    Cationic host defence peptides (CHDP; also known as antimicrobial peptides) are key components of the immune response in the female reproductive tract. The role of the placental trophoblast in ovine host defence remains poorly understood. This study characterises expression of genes for cathelicidin and defensin peptides in primary ovine placental tissues, the ovine trophoblast cell line (AH-1) and in response to the TLR-4 ligand LPS, the abortifacient organism Waddlia chondrophila and 1α,25-dihydroxyvitamin D3. Using RT-PCR, expression of the CHDP SMAP-29, sBD-1 and sBD-2 was assessed in the AH-1 cell line in response to LPS, 1α,25-dihydroxyvitamin D3 exposure (a known stimulator of cathelicidin gene expression), or W. chondrophila infection. Expression of cathelicidin in the trophoblast compartment of the ovine placenta and in the ovine trophoblast cell line (AH-1) was also established. AH-1 cells did not upregulate expression of CHDP in response to LPS, but sBD-1 and sBD-2 expression was significantly increased in response to W. chondrophila infection. SMAP-29 expression was not altered by in vitro exposure to 1α,25-dihydroxyvitamin D3. This study demonstrates that the ovine trophoblast expresses cathelicidins, but does not upregulate expression of CHDP in response to LPS. Ovine trophoblasts are shown to differentially regulate expression of CHDP and lack a demonstrable vitamin D-mediated cathelicidin response. PMID:27348190

  19. Rapid host immune response and viral dynamics in herpes simplex virus-2 infection

    PubMed Central

    Schiffer, Joshua T; Corey, Lawrence

    2014-01-01

    Herpes Simplex Virus-2 (HSV-2) is episodically shed throughout the human genital tract. While high viral load correlates with development of genital ulcers, shedding also commonly occurs even when ulcers are not present, allowing for silent transmission during coitus and contributing to high seroprevalence of HSV-2 worldwide. Frequent viral reactivation occurs despite diverse and complementary host and viral mechanisms within ganglionic tissue that predispose towards latency, suggesting that viral replication may be constantly occurring in a small minority of neurons within the ganglia. Within genital mucosa, the in vivo expansion and clearance rates of HSV-2 are extremely rapid. Resident dendritic cells and memory HSV-specific T cells persist at prior sites of genital tract reactivation, and in conjunction with prompt innate recognition of infected cells, lead to rapid containment of infected cells. Shedding episodes vary greatly in duration and severity within a single person over time: this heterogeneity appears best explained by variation in the densities of host immunity across the genital tract. The fact that immune responses usually control viral replication in genital skin prior to development of lesions provides optimism that enhancing such responses could lead to effective vaccines and immunotherapies. PMID:23467247

  20. Sheep primary cells as in vitro models to investigate Mycoplasma agalactiae host cell interactions.

    PubMed

    Hegde, Shrilakshmi; Gabriel, Cordula; Kragl, Martin; Chopra-Dewasthaly, Rohini

    2015-10-01

    Appropriate infection models are imperative for the understanding of pathogens like mycoplasmas that are known for their strict host and tissue specificity, and lack of suitable cell and small animal models has hindered pathogenicity studies. This is particularly true for the economically important group of ruminant mycoplasmas whose virulence factors need to be elucidated for designing effective intervention strategies. Mycoplasma agalactiae serves as a useful role model especially because it is phylogenetically very close to M. bovis and causes similar symptoms by as yet unknown mechanisms. Here, we successfully prepared and characterized four different primary sheep cell lines, namely the epithelial and stromal cells from the mammary gland and uterus, respectively. Using immunohistochemistry, we identified vimentin and cytokeratin as specific markers to confirm the typical cell phenotypes of these primary cells. Furthermore, M. agalactiae's consistent adhesion and invasion into these primary cells proves the reliability of these cell models. Mimicking natural infections, mammary epithelial and stromal cells showed higher invasion and adhesion rates compared to the uterine cells as also seen via double immunofluorescence staining. Altogether, we have generated promising in vitro cell models to study host-pathogen interactions of M. agalactiae and related ruminant pathogens in a more authentic manner.

  1. Advances in Modern Botnet Understanding and the Accurate Enumeration of Infected Hosts

    ERIC Educational Resources Information Center

    Nunnery, Christopher Edward

    2011-01-01

    Botnets remain a potent threat due to evolving modern architectures, inadequate remediation methods, and inaccurate measurement techniques. In response, this research exposes the architectures and operations of two advanced botnets, techniques to enumerate infected hosts, and pursues the scientific refinement of infected-host enumeration data by…

  2. Enhancement of host resistance against Listeria infection by Lactobacillus casei: Role of macrophages

    SciTech Connect

    Sato, K.

    1984-05-01

    Among the 10 species of the genus Lactobacillus, L. casei showed the strongest protective action against Listeria monocytogenes infection in mice. The activity of L. casei differed with regard to the dose of administration. The anti-L. monocytogenes resistance in mice intravenously administered 5.5 X 10(7), 2.8 X 10(8), or 1.1 X 10(9) L. casei cells was most manifest at ca. 2, 2 and 13, and 3 to 21 days after its administration, respectively. The growth of L. monocytogenes in the liver of mice injected with L. casei (10(7), 10(8), or 10(9) cells) 48 h after infection was suppressed, particularly when 10(8) or 10(9) L. casei cells were given 2 or 13 days before the induced infection, respectively. This suppression of L. monocytogenes growth was overcome by carrageenan treatment or X-ray irradiation. (/sup 3/H)thymidine incorporation into the liver DNA increased 13 days after administration of L. casei, and augmentation of (/sup 3/H)thymidine incorporation during 6 to 48 h after infection was dependent on the dose of L. casei. Peritoneal macrophage accumulation observed 1 to 5 days after intraperitoneal injection of UV-killed L. monocytogenes was markedly enhanced when the mice were treated with L. casei cells 13 days before macrophage elicitation. Therefore, the enhanced host resistance by L. casei to L. monocytogenes infection may be mediated by macrophages migrating from the blood stream to the reticuloendothelial system in response to L. casei injection before or after L. monocytogenes infection.

  3. Enhancement of host resistance against Listeria infection by Lactobacillus casei: role of macrophages.

    PubMed Central

    Sato, K

    1984-01-01

    Among the 10 species of the genus Lactobacillus, L. casei showed the strongest protective action against Listeria monocytogenes infection in mice. The activity of L. casei differed with regard to the dose of administration. The anti-L. monocytogenes resistance in mice intravenously administered 5.5 X 10(7), 2.8 X 10(8), or 1.1 X 10(9) L. casei cells was most manifest at ca. 2, 2 and 13, and 3 to 21 days after its administration, respectively. The growth of L. monocytogenes in the liver of mice injected with L. casei (10(7), 10(8), or 10(9) cells) 48 h after infection was suppressed, particularly when 10(8) or 10(9) L. casei cells were given 2 or 13 days before the induced infection, respectively. This suppression of L. monocytogenes growth was overcome by carrageenan treatment or X-ray irradiation. [3H]thymidine incorporation into the liver DNA increased 13 days after administration of L. casei, and augmentation of [3H]thymidine incorporation during 6 to 48 h after infection was dependent on the dose of L. casei. Peritoneal macrophage accumulation observed 1 to 5 days after intraperitoneal injection of UV-killed L. monocytogenes was markedly enhanced when the mice were treated with L. casei cells 13 days before macrophage elicitation. Therefore, the enhanced host resistance by L. casei to L. monocytogenes infection may be mediated by macrophages migrating from the blood stream to the reticuloendothelial system in response to L. casei injection before or after L. monocytogenes infection. Images PMID:6425222

  4. Investigation of Host and Pathogen Contributions to Infectious Colitis Using the Citrobacter rodentium Mouse Model of Infection.

    PubMed

    Bosman, Else S; Chan, Justin M; Bhullar, Kirandeep; Vallance, Bruce A

    2016-01-01

    Citrobacter rodentium is used as a model organism to study enteric bacterial infections in mice. Infection occurs via the oral-fecal route and results in the pathogen forming attaching and effacing lesions on infected epithelial cells. Moreover, infection leads to a subsequent host-mediated form of colitis. C. rodentium infection is thus an excellent model to study infectious colitis in vivo, while the ability to genetically manipulate C. rodentium virulence genes provides the opportunity to develop clear insights into the pathogenesis of this and related infectious microbes. This chapter outlines the basic techniques involved in setting up a C. rodentium infection in mice and several different methodologies to assess the severity of the infection.

  5. 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.

  6. Widespread disruption of host transcription termination in HSV-1 infection

    PubMed Central

    Rutkowski, Andrzej J.; Erhard, Florian; L'Hernault, Anne; Bonfert, Thomas; Schilhabel, Markus; Crump, Colin; Rosenstiel, Philip; Efstathiou, Stacey; Zimmer, Ralf; Friedel, Caroline C.; Dölken, Lars

    2015-01-01

    Herpes simplex virus 1 (HSV-1) is an important human pathogen and a paradigm for virus-induced host shut-off. Here we show that global changes in transcription and RNA processing and their impact on translation can be analysed in a single experimental setting by applying 4sU-tagging of newly transcribed RNA and ribosome profiling to lytic HSV-1 infection. Unexpectedly, we find that HSV-1 triggers the disruption of transcription termination of cellular, but not viral, genes. This results in extensive transcription for tens of thousands of nucleotides beyond poly(A) sites and into downstream genes, leading to novel intergenic splicing between exons of neighbouring cellular genes. As a consequence, hundreds of cellular genes seem to be transcriptionally induced but are not translated. In contrast to previous reports, we show that HSV-1 does not inhibit co-transcriptional splicing. Our approach thus substantially advances our understanding of HSV-1 biology and establishes HSV-1 as a model system for studying transcription termination. PMID:25989971

  7. Minimal within-host dengue models highlight the specific roles of the immune response in primary and secondary dengue infections.

    PubMed

    Ben-Shachar, Rotem; Koelle, Katia

    2015-02-01

    In recent years, the within-host viral dynamics of dengue infections have been increasingly characterized, and the relationship between aspects of these dynamics and the manifestation of severe disease has been increasingly probed. Despite this progress, there are few mathematical models of within-host dengue dynamics, and the ones that exist focus primarily on the general role of immune cells in the clearance of infected cells, while neglecting other components of the immune response in limiting viraemia. Here, by considering a suite of mathematical within-host dengue models of increasing complexity, we aim to isolate the critical components of the innate and the adaptive immune response that suffice in the reproduction of several well-characterized features of primary and secondary dengue infections. By building up from a simple target cell limited model, we show that only the innate immune response is needed to recover the characteristic features of a primary symptomatic dengue infection, while a higher rate of viral infectivity (indicative of antibody-dependent enhancement) and infected cell clearance by T cells are further needed to recover the characteristic features of a secondary dengue infection. We show that these minimal models can reproduce the increased risk of disease associated with secondary heterologous infections that arises as a result of a cytokine storm, and, further, that they are consistent with virological indicators that predict the onset of severe disease, such as the magnitude of peak viraemia, time to peak viral load, and viral clearance rate. Finally, we show that the effectiveness of these virological indicators to predict the onset of severe disease depends on the contribution of T cells in fuelling the cytokine storm.

  8. Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells.

    PubMed

    Wunsch, Christopher M; Lewis, Janina P

    2015-12-17

    Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth. The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2',7'-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal

  9. Enterovirus71 (EV71) Utilise Host microRNAs to Mediate Host Immune System Enhancing Survival during Infection

    PubMed Central

    Lui, Yan Long Edmund; Tan, Tuan Lin; Woo, Wee Hong; Timms, Peter; Hafner, Louise Marie; Tan, Kian Hwa; Tan, Eng Lee

    2014-01-01

    Hand, Foot and Mouth Disease (HFMD) is a self-limiting viral disease that mainly affects infants and children. In contrast with other HFMD causing enteroviruses, Enterovirus71 (EV71) has commonly been associated with severe clinical manifestation leading to death. Currently, due to a lack in understanding of EV71 pathogenesis, there is no antiviral therapeutics for the treatment of HFMD patients. Therefore the need to better understand the mechanism of EV71 pathogenesis is warranted. We have previously reported a human colorectal adenocarcinoma cell line (HT29) based model to study the pathogenesis of EV71. Using this system, we showed that knockdown of DGCR8, an essential cofactor for microRNAs biogenesis resulted in a reduction of EV71 replication. We also demonstrated that there are miRNAs changes during EV71 pathogenesis and EV71 utilise host miRNAs to attenuate antiviral pathways during infection. Together, data from this study provide critical information on the role of miRNAs during EV71 infection. PMID:25047717

  10. Enterovirus71 (EV71) utilise host microRNAs to mediate host immune system enhancing survival during infection.

    PubMed

    Lui, Yan Long Edmund; Tan, Tuan Lin; Woo, Wee Hong; Timms, Peter; Hafner, Louise Marie; Tan, Kian Hwa; Tan, Eng Lee

    2014-01-01

    Hand, Foot and Mouth Disease (HFMD) is a self-limiting viral disease that mainly affects infants and children. In contrast with other HFMD causing enteroviruses, Enterovirus71 (EV71) has commonly been associated with severe clinical manifestation leading to death. Currently, due to a lack in understanding of EV71 pathogenesis, there is no antiviral therapeutics for the treatment of HFMD patients. Therefore the need to better understand the mechanism of EV71 pathogenesis is warranted. We have previously reported a human colorectal adenocarcinoma cell line (HT29) based model to study the pathogenesis of EV71. Using this system, we showed that knockdown of DGCR8, an essential cofactor for microRNAs biogenesis resulted in a reduction of EV71 replication. We also demonstrated that there are miRNAs changes during EV71 pathogenesis and EV71 utilise host miRNAs to attenuate antiviral pathways during infection. Together, data from this study provide critical information on the role of miRNAs during EV71 infection.

  11. Fighting the Monster: Applying the Host Damage Framework to Human Central Nervous System Infections

    PubMed Central

    Panackal, Anil A.; Williamson, Kim C.; van de Beek, Diederik; Boulware, David R.

    2016-01-01

    ABSTRACT The host damage-response framework states that microbial pathogenesis is a product of microbial virulence factors and collateral damage from host immune responses. Immune-mediated host damage is particularly important within the size-restricted central nervous system (CNS), where immune responses may exacerbate cerebral edema and neurological damage, leading to coma and death. In this review, we compare human host and therapeutic responses in representative nonviral generalized CNS infections that induce archetypal host damage responses: cryptococcal menigoencephalitis and tuberculous meningitis in HIV-infected and non-HIV-infected patients, pneumococcal meningitis, and cerebral malaria. Consideration of the underlying patterns of host responses provides critical insights into host damage and may suggest tailored adjunctive therapeutics to improve disease outcome. PMID:26814182

  12. Pseudomonas fluorescens: iron-responsive proteins and their involvement in host infection.

    PubMed

    Sun, Yuan-yuan; Sun, Li

    2015-04-17

    For pathogenic bacteria, the ability to acquire iron is vital to survival in the host. In consequence, many genes involved in iron acquisition are associated with bacterial virulence. Pseudomonas fluorescens is a bacterial pathogen to a variety of farmed fish. However, the global regulatory function of iron in pathogenic P. fluorescens is essentially unknown. In this study, in order to identify proteins affected by iron condition at the expression level, we performed proteomic analysis to compare the global protein profiles of P. fluorescens strain TSS, a fish pathogen, cultured under iron-replete and iron-deplete conditions. Twenty-two differentially expressed proteins were identified, most of which were confirmed to be regulated by iron at the mRNA level. To investigate their potential involvement in virulence, the genes encoding four of the 22 proteins, i.e. HemO (heme oxygenase), PspB (serine protease), Sod (superoxide dismutase), and TfeR (TonB-dependent outermembrane ferric enterobactin receptor), were knocked out, and the pathogenicity of the mutants was examined in a model of turbot (Scophthalmus maximus). The results showed that compared to the wild type, the hemO, pspB, and tfeR knockouts were significantly impaired in the ability to survive in host serum, to invade host tissues, and to cause host mortality. Immunization of turbot with recombinant TfeR (rTfeR) and PspB induced production of specific serum antibodies and significant protections against lethal TSS challenge. Further analysis showed that rTfeR antibodies recognized and bound to TSS, and that treatment of TSS with rTfeR antibodies significantly impaired the infectivity of TSS to fish cells. Taken together, these results indicate for the first time that in pathogenic P. fluorescens, iron affects the expression of a large number of proteins including those that are involved in host infection.

  13. Identifying Francisella tularensis genes required for growth in host cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technical Abstract: Francisella tularensis is a highly virulent Gram negative intracellular pathogen capable of infecting a vast diversity of hosts, ranging from amoebae to humans. A hallmark of F. tularensis virulence is its ability to quickly grow to high densities within a diverse set of host cel...

  14. Delivery of host cell-directed therapeutics for intracellular pathogen clearance

    PubMed Central

    Collier, Michael A.; Gallovic, Matthew D.; Peine, Kevin J.; Duong, Anthony D.; Bachelder, Eric M.; Gunn, John S.; Schlesinger, Larry S.; Ainslie, Kristy M.

    2014-01-01

    Intracellular pathogens present a major health risk because of their innate ability to evade clearance. Their location within host cells and ability to react to the host environment by mutation or transcriptional changes often enables survival mechanisms to resist standard therapies. Host-directed drugs do not target the pathogen, minimizing the potential development of drug resistance; however, they can be difficult to deliver efficiently to intracellular sites. Vehicle delivery of host-mediated response drugs not only improves drug distribution and toxicity profiles, but can reduce the total amount of drug necessary to clear infection. In this article, we will review some host-directed drugs and current drug delivery techniques that can be used to efficiently clear intracellular infections. PMID:24134600

  15. Natural killer cells in hepatitis B virus infection.

    PubMed

    Wu, Shao-fei; Wang, Wen-jing; Gao, Yue-qiu

    2015-01-01

    Natural killer cells are a unique type of lymphocytes with cytotoxic capacity, and play important roles against tumors and infections. Recently, natural killer cells have been increasingly valued in their effects in hepatitis B virus infection. Since hepatitis B virus is not cytopathic, the subsequent antiviral immune responses of the host are responsible for sustaining the liver injury, which may result in cirrhosis and even hepatocellular carcinoma. Many studies have confirmed that natural killer cells participate in anti-hepatitis B virus responses both in the early phase after infection and in the chronic phase via cytolysis, degranulation, and cytokine secretion. However, natural killer cells play dichotomic roles: they exert antiviral and immunoregulatory functions whilst contribute to the pathogenesis of liver injury. Here, we review the roles of natural killer cells in hepatitis B virus infection, introducing novel therapeutic strategies for controlling hepatitis B virus infection via the modulation of natural killer cells.

  16. Resource limitation alters the consequences of co-infection for both hosts and parasites.

    PubMed

    Budischak, Sarah A; Sakamoto, Kaori; Megow, Lindsey C; Cummings, Kelly R; Urban, Joseph F; Ezenwa, Vanessa O

    2015-06-01

    Most animals are concurrently infected with multiple parasite species and live in environments with fluctuating resource availability. Resource limitation can influence host immune responses and the degree of competition between co-infecting parasites, yet its effects on individual health and pathogen transmission have not been studied for co-infected hosts. To test how resource limitation affects immune trade-offs and co-infection outcomes, we conducted a factorial experiment using laboratory mice. Mice were given a standard or low protein diet, dosed with two species of helminths (alone and in combination), and then challenged with a microparasite. Using a community ecology trophic framework, we found that co-infection influenced parasite survival and reproduction via host immunity, but the magnitude and direction of responses depended on resources and the combination of co-infecting parasites. Our findings highlight that resources and their consequence for host defenses are a key context that shapes the magnitude and direction of parasite interactions.

  17. Molecular and cellular mechanisms involved in the Trypanosoma cruzi/host cell interplay.

    PubMed

    Romano, Patricia Silvia; Cueto, Juan Agustín; Casassa, Ana Florencia; Vanrell, María Cristina; Gottlieb, Roberta A; Colombo, María Isabel

    2012-05-01

    The protozoan parasite Trypanosoma cruzi has a complex biological cycle that involves vertebrate and invertebrate hosts. In mammals, the infective trypomastigote form of this parasite can invade several cell types by exploiting phagocytic-like or nonphagocytic mechanisms depending on the class of cell involved. Morphological studies showed that when trypomastigotes contact macrophages, they induce the formation of plasma membrane protrusions that differ from the canonical phagocytosis that occurs in the case of noninfective epimastigotes. In contrast, when trypomastigotes infect epithelial or muscle cells, the cell surface is minimally modified, suggesting the induction of a different class of process. Lysosomal-dependent or -independent T. cruzi invasion of host cells are two different models that describe the molecular and cellular events activated during parasite entry into nonphagocytic cells. In this context, we have previously shown that induction of autophagy in host cells before infection favors T. cruzi invasion. Furthermore, we demonstrate that autophagosomes and the autophagosomal protein LC3 are recruited to the T. cruzi entry sites and that the newly formed T. cruzi parasitophorous vacuole has characteristics of an autophagolysosome. This review summarizes the current knowledge of the molecular and cellular mechanisms of T. cruzi invasion in nonphagocytic cells. Based on our findings, we propose a new model in which T. cruzi takes advantage of the upregulation of autophagy during starvation to increase its successful colonization of host cells.

  18. Molecular and Cellular Mechanisms Involved in the Trypanosoma cruzi/Host Cell Interplay

    PubMed Central

    Romano, Patricia Silvia; Cueto, Juan Agustín; Casassa, Ana Florencia; Vanrell, María Cristina; Gottlieb, Roberta A.; Colombo, María Isabel

    2013-01-01

    Summary The protozoan parasite Trypanosoma cruzi has a complex bi-ological cycle that involves vertebrate and invertebrate hosts. In mammals, the infective trypomastigote form of this parasite can invade several cell types by exploiting phagocytic-like or non-phagocytic mechanisms depending on the class of cell involved. Morphological studies showed that when trypomastigotes contact macrophages, they induce the formation of plasma membrane protrusions that differ from the canonical phagocytosis that occurs in the case of noninfective epimastigotes. In contrast, when trypomastigotes infect epithelial or muscle cells, the cell surface is minimally modified, suggesting the induction of a different class of process. Lysosomal-dependent or -independent T. cruzi invasion of host cells are two different models that describe the molecular and cellular events activated during parasite entry into nonphagocytic cells. In this context, we have previously shown that induction of autophagy in host cells before infection favors T. cruzi invasion. Furthermore, we demonstrate that autophagosomes and the autophagosomal protein LC3 are recruited to the T. cruzi entry sites and that the newly formed T. cruzi parasitophorous vacuole has characteristics of an autophagolysosome. This review summarizes the current knowledge of the molecular and cellular mechanisms of T. cruzi invasion in nonphagocytic cells. Based on our findings, we propose a new model in which T. cruzi takes advantage of the up-regulation of autophagy during starvation to increase its successful colonization of host cells. PMID:22454195

  19. Conflict between parasites with different transmission strategies infecting an amphipod host.

    PubMed

    Haine, Eleanor R; Boucansaud, Karelle; Rigaud, Thierry

    2005-12-01

    Competition between parasites within a host can influence the evolution of parasite virulence and host resistance, but few studies examine the effects of unrelated parasites with conflicting transmission strategies infecting the same host. Vertically transmitted (VT) parasites, transmitted from mother to offspring, are in conflict with virulent, horizontally transmitted (HT) parasites, because healthy hosts are necessary to maximize VT parasite fitness. Resolution of the conflict between these parasites should lead to the evolution of one of two strategies: avoidance, or sabotage of HT parasite virulence by the VT parasite. We investigated two co-infecting parasites in the amphipod host, Gammarus roeseli: VT microsporidia have little effect on host fitness, but acanthocephala modify host behaviour, increasing the probability that the amphipod is predated by the acanthocephalan's definitive host. We found evidence for sabotage: the behavioural manipulation induced by the Acanthocephala Polymorphus minutus was weaker in hosts also infected by the microsporidia Dictyocoela sp. (roeselum) compared to hosts infected by P. minutus alone. Such conflicts may explain a significant portion of the variation generally observed in behavioural measures, and since VT parasites are ubiquitous in invertebrates, often passing undetected, conflict via transmission may be of great importance in the study of host-parasite relationships.

  20. Glutathione Reductase Is Essential for Host Defense against Bacterial Infection

    PubMed Central

    Yan, Jing; Ralston, Melissa M.; Meng, Xiaomei; Bongiovanni, Kathleen D.; Jones, Amanda L.; Benndorf, Rainer; Nelin, Leif D.; Frazier, W. Joshua; Rogers, Lynette K.; Smith, Charles V.; Liu, Yusen

    2013-01-01

    Glutathione reductase (Gsr)1 catalyzes the reduction of glutathione disulfide to glutathione, a major cellular antioxidant. We have recently shown that Gsr is essential for host defense against the Gram-negative bacteria Escherichia coli in a mouse model of sepsis. While we have demonstrated that Gsr is required for sustaining the oxidative burst and the development of neutrophil extracellular traps, the role of Gsr in other phagocytic functions remains unclear. It is also unclear whether Gsr-deficient mice exhibit host defense defects against Gram-positive bacteria. In the present study, we characterized the effects of Gsr deficiency on the innate immune responses to a Gram-positive bacterium, group B Streptococcus, and to the Gram-negative bacterial cell wall component lipopolysaccharide (LPS). We found that like, E. coli, group B Streptococcus resulted in a substantially more robust cytokine response and a markedly higher morbidity and mortality in Gsr-deficient mice than in wildtype mice. The increased morbidity and mortality were associated with greater bacterial burden in the Gsr-deficient mice. Interestingly, Gsr-deficient mice did not exhibit a greater sensitivity to LPS than did wildtype mice. Analysis of the neutrophils of Gsr-deficient mice revealed impaired phagocytosis. In response to thioglycollate stimulation, Gsr-deficient mice mobilized far fewer phagocytes, including neutrophils, macrophages, and eosinophils, into their peritoneal cavities than did wildtype mice. The defective phagocyte mobilization is associated with profound oxidation and aggregation of ascitic proteins, particularly albumin. Our results indicate that the oxidative defense mechanism mediated by Gsr is required for an effective innate immune response against bacteria, likely by preventing phagocyte dysfunction due to oxidative damage. PMID:23623936

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