Project description:Medieval Yersinia pestis strains from Latvia show low abundance of the pla gene and reduced virulence at the end of the second plague pandemic
Project description:A delay in the mammalian inflammatory response is a prominent feature of infection with Yersinia pestis, the agent of bubonic and pneumonic plague. Y. pestis factors have been identified that either do not stimulate a normal inflammatory response, or actively suppress it. Prominent among these are components of the Type III secretion system that is encoded on the Yersinia virulence plasmid (pYV). We used a rat model of bubonic plague to characterize the kinetics and extent of the mammalian transcriptomic response to infection with wild-type or pYV-negative Y. pestis in the draining lymph node. Remarkably, dissemination and multiplication of wild-type Y. pestis during the bubonic stage of disease did not induce any detectable gene expression response by host lymph node cells. This was followed, however, by an extensive transcriptomic response, including upregulation of several cytokine, chemokine, and other immune response genes, after systemic spread during septicemic plague. Matched lymph node samples used for histopathology and extracellular cytokine measurements, combined with the microarray data set, broadly outlined the mammalian immune response to Y. pestis and how it is influenced by pYV-encoded factors. The results indicate that both WT and pYV– Y. pestis induce primarily a Th17 response, and not a Th1 or Th2 response. In the absence of pYV, a sustained recruitment of polymorphonuclear leukocytes, the major Th17 effector cell, to the lymph node resulted in clearance of infection. Thus, the ability to counteract a Th17- driven PMN response in the lymph node appears to be a major function of the Y. pestis virulence plasmid. In contrast, classic markers of the proinflammatory response and macrophage activation, such as TNF-á and IFN-ã, were not induced at all by pYV– Y. pestis, and appeared only late in infection with WT Y. pestis.
Project description:A delay in the mammalian inflammatory response is a prominent feature of infection with Yersinia pestis, the agent of bubonic and pneumonic plague. Y. pestis factors have been identified that either do not stimulate a normal inflammatory response, or actively suppress it. Prominent among these are components of the Type III secretion system that is encoded on the Yersinia virulence plasmid (pYV). We used a rat model of bubonic plague to characterize the kinetics and extent of the mammalian transcriptomic response to infection with wild-type or pYV-negative Y. pestis in the draining lymph node. Remarkably, dissemination and multiplication of wild-type Y. pestis during the bubonic stage of disease did not induce any detectable gene expression response by host lymph node cells. This was followed, however, by an extensive transcriptomic response, including upregulation of several cytokine, chemokine, and other immune response genes, after systemic spread during septicemic plague. Matched lymph node samples used for histopathology and extracellular cytokine measurements, combined with the microarray data set, broadly outlined the mammalian immune response to Y. pestis and how it is influenced by pYV-encoded factors. The results indicate that both WT and pYV– Y. pestis induce primarily a Th17 response, and not a Th1 or Th2 response. In the absence of pYV, a sustained recruitment of polymorphonuclear leukocytes, the major Th17 effector cell, to the lymph node resulted in clearance of infection. Thus, the ability to counteract a Th17- driven PMN response in the lymph node appears to be a major function of the Y. pestis virulence plasmid. In contrast, classic markers of the proinflammatory response and macrophage activation, such as TNF-á and IFN-ã, were not induced at all by pYV– Y. pestis, and appeared only late in infection with WT Y. pestis. Rats treated with PBS and Yersinia pestis at various time points.
Project description:During pneumonic plague, the bacterium Yersinia pestis elicits the development of inflammatory lung lesions that continue to expand throughout infection. This lesion development and persistence is poorly understood. Here, we examine spatially distinct regions of lung lesions using laser capture microdissection and RNAseq analysis to identify transcriptional differences between lesion microenvironments. We show that cellular pathways involved in leukocyte migration and apoptosis are down regulated in the center of lung lesions compared to the periphery. Probing for the bacterial factor(s) important for the alteration in neutrophil survival, we show both in vitro and in vivo that Y. pestis increases neutrophil survival in a manner that is dependent on the type-III secretion system effector YopM. This research explores the complexity of spatially distinct host - microbe interactions and emphasizes the importance of cell relevance in assays in order to fully understand Y. pestis virulence.
Project description:During pneumonic plague, the bacterium Yersinia pestis elicits the development of inflammatory lung lesions that continue to expand throughout infection. This lesion development and persistence is poorly understood. Here, we examine spatially distinct regions of lung lesions using laser capture microdissection and RNAseq analysis to identify transcriptional differences between lesion microenvironments. We show that cellular pathways involved in leukocyte migration and apoptosis are down regulated in the center of lung lesions compared to the periphery. Probing for the bacterial factor(s) important for the alteration in neutrophil survival, we show both in vitro and in vivo that Y. pestis increases neutrophil survival in a manner that is dependent on the type-III secretion system effector YopM. This research explores the complexity of spatially distinct host - microbe interactions and emphasizes the importance of cell relevance in assays in order to fully understand Y. pestis virulence. We examine spatially distinct regions of lung lesions using laser capture microdissection and RNAseq analysis to identify transcriptional differences between lesion microenvironments. Sample types: uninfected BM-PMN, infected BM-PMN, lesion periphery, lesion center.
Project description:Pneumonic plague is the most deadly form of infection caused by Yersinia pestis and can progress extremely fast. However, our understanding on the host transcriptomic response to pneumonic plague is insufficient. Here, we used RNA-sequencing technology to analyze transcriptomic responses in mice infected with fully virulent strain 201 or EV76, a live attenuated vaccine strain lacking the pigmentation locus. Approximately 600 differentially expressed genes (DEGs) were detected in lungs from both 201- and EV76-infected mice at 12 hours post-infection (hpi). DEGs in lungs of 201-infected mice exceeded 2,000 at 48 hpi, accompanied by sustained large numbers of DEGs in the liver and spleen; however, limited DEGs were detected in those organs of EV-infected mice. Remarkably, DEGs in lungs were significantly enriched in critical immune responses pathways in EV76-infected but not 201-infected mice, including antigen processing and presentation, T cell receptor signaling among others. Pathological and bacterial load analyses confirmed the rapid systemic dissemination of 201-infection and the confined EV76-infection in lungs. Our results demonstrate that fully virulent Y. pestis strongly inhibits both the innate and adaptive immune responses that are substantially stimulated in a self-limited infection, which update our holistic views on the transcriptomic response to pneumonic plague.