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.
Project description:Yersinia pestis causes bubonic plague in humans and rats. The disease is characterized by an enlarged, painful lymph node, termed a bubo, that develops following bacterial dissemination from an intradermal flea bite injection site. In susceptible animals, the bacteria quickly overcome host innate immune defenses in the lymph node, spread systemically through the blood, and produce fatal sepsis 1,2. At the terminal stage of disease, the bubo contains massive numbers of extracellular bacteria, necrotic lymphoid tissue, hemorrhage, and fibrin 2. The extreme virulence of Y. pestis has been largely ascribed to its ability to avoid innate immunity by preventing phagocytosis, selectively killing immune cells, and down regulating the proinflammatory response 3. Here we report that two innate immune effector mechanisms are generated during bubonic plague in the rat: iron limitation and nitrosative stress. The expression of nitric oxide synthase (iNOS) by rat polymorphonuclear neutrophils (PMNs) was induced in the bubo, and mutation of the Y. pestis hmp gene, which encodes a flavohemoglobin important for resistance to nitric oxide (NO), attenuated virulence. Thus, although Y. pestis avoids uptake and intracellular killing by phagocytes, it still encounters innate immune effector molecules, particularly phagocyte-derived reactive nitrogen species, in the extracellular environment of the bubo. Keywords: repeat
Project description:The plague agent, Yersinia pestis, employs a type III secretion system (T3SS) to selectively destroy human immune cells, thereby enabling its replication in the bloodstream and transmission to new hosts via fleabite. The host factors responsible for the selective destruction of immune cells by plague bacteria were not known. Here we show that LcrV, the needle cap protein of the Y. pestis T3SS, binds N-formylpeptide receptor (FPR1) on human immune cells to promote the translocation of bacterial effectors.
Project description:The etiologic agent of bubonic plague, Yersinia pestis, senses cell density-dependent chemical signals to synchronize transcription between cells of the population in a process named quorum sensing. Though the closely related enteric pathogen Y. pseudotuberculosis uses quorum sensing system to regulate motility, the role of YpeIR quorum sensing in Y. pestis has been unclear. YpeIR is one of the AHL quorum sensing system in Y. pestis. In this study we performed transcriptional profiling experiments to identify Y. pestis YpeIR quorum sensing regulated functions at 37°C.
Project description:Yersinia pestis, the etiological agent of plague, is able to sense cell density by quorum sensing. The function of quorum sensing in Y. pestis is not clear. Here, the process of autoinducer-2 (AI-2) quorum sensing was investigated by comparing transcript profiles when AI-2 quorum-sensing signal is added in to control. The strain Δpgm (pigmentation-negative) mutant was used as wild type.The control consisted of cells grown and treated under the same conditions without added signals.