Project description:We identified four virulence phenotypes of Rickettsia prowazekii (the deadly agent of epidemic typhus) that are associated with the upregulation of antiapoptotic genes (virulent strain) or the Interferon I pathway (avirulent). Transcriptional and proteomic analyses of R. prowazekii linked surface protein expression and methylation with virulence. By sequencing a virulent strain and using comparative genomics, we found hotspots of mutations in homopolymeric tracts of poly(A) and poly(T) that lead to gene split and inactivation and explain the loss of virulence in the vaccine strain. These areas of instability explains adaptive mutations leading to virulence recovery in the vaccine strain. Transcriptional analysis of two different strains growing in L929 cells. A virulent strain (Rp22) was compared to a avirulent strain (Erus). The experiment was performed with 3 independant biological replicates.
Project description:We identified four virulence phenotypes of Rickettsia prowazekii (the deadly agent of epidemic typhus) that are associated with the upregulation of antiapoptotic genes (virulent strain) or the Interferon I pathway (avirulent). Transcriptional and proteomic analyses of R. prowazekii linked surface protein expression and methylation with virulence. By sequencing a virulent strain and using comparative genomics, we found hotspots of mutations in homopolymeric tracts of poly(A) and poly(T) that lead to gene split and inactivation and explain the loss of virulence in the vaccine strain. These areas of instability explains adaptive mutations leading to virulence recovery in the vaccine strain.
Project description:We identified four virulence phenotypes of Rickettsia prowazekii (the deadly agent of epidemic typhus) that are associated with the upregulation of antiapoptotic genes (virulent strain) or the Interferon I pathway (avirulent). Transcriptional and proteomic analyses of R. prowazekii linked surface protein expression and methylation with virulence. By sequencing a virulent strain and using comparative genomics, we found hotspots of mutations in homopolymeric tracts of poly(A) and poly(T) that lead to gene split and inactivation and explain the loss of virulence in the vaccine strain. These areas of instability explains adaptive mutations leading to virulence recovery in the vaccine strain.
Project description:Strains of R. rickettsii, the agent of Rocky Mountain spotted fever, differ greatly in the severity of the disease caused. The genetic differences responsible for this disparity are only now being uncovered. An avirulent, laboratory adapted strain of R. rickettsii fails to proteolytically process several large surface protein antigens. We have identified a protease that cleaves the protein precursors to their mature form. The gene encoding this protease is mutated in the avirulent strain. Complementation of the active form of the gene identifies proteolytic processing of surface antigens as important to virulence.
Project description:Rickettsia conorii is the etiologic agent of Mediterranean spotted fever, a re-emerging disease with significant mortality. This obligate, gram-negative intracellular pathogen is transmitted via tick bites, resulting in disseminated vascular endothelial cell infection with vascular leakage. In the infected human, Rickettsia conorii infects endothelial cells, stimulating expression of cytokines and pro-coagulant factors. However, the integrated proteomic response of human endothelial cells to R. conorii infection is not known. In this study, we performed quantitative proteomic profiling of R conorii –infected primary HUVECs vs those stimulated with LPS alone.
