Project description:Bartonelloses are neglected emerging infectious diseases caused by facultatively intracellular bacteria transmitted between vertebrate hosts by various arthropod vectors. The highest diversity of Bartonella species has been identified in rodents. Within this study we focused on the edible dormouse (Glis glis), a rodent with unique life-history traits that often enters households and whose possible role in the epidemiology of Bartonella infections had been previously unknown. We identified and cultivated two distinct Bartonella sub(species) significantly diverging from previously described species, which were characterized using growth characteristics, biochemical tests, and various molecular techniques including also proteomics. Two novel (sub)species were described: Bartonella grahamii subsp. shimonis subsp. nov. and Bartonella gliris sp. nov.We sequenced two individual strains per each described (sub)species. During exploratory genomic analyses comparing two genotypes ultimately belonging to the same species, both factually and most importantly even spatiotemporally, we noticed unexpectedly significant structural variation between them. We found that most of the detected structural variants could be explained either by prophage excision or integration. Based on a detailed study of one such event, we argue that prophage deletion represents the most probable explanation of the observed phenomena.Moreover, in one strain of Bartonella grahamii subsp. shimonis subsp. nov. we identified a deletion related to Bartonella Adhesin A, a major pathogenicity factor that modulates bacteria-host interactions. Altogether, our results suggest that even a limited number of passages induced sufficient selective pressure to promote significant changes at the level of the genome.
Project description:In order to select genes that are differentially expressed in salivary glands during Ixodes ricinus infection by Bartonella henselae we compare the transcriptome of infected and non-infected salivary glands
Project description:Antibodies are key to the clearance of Bartonella bacteremia, but the mechanisms and targets of protective antibodies are unknown and bacterial evasion strategies remain elusive. We studied experimental Bartonella taylorii infection of mice, its natural host, and investigated protective immune responses. Clearance of bacteremia depended on specific antibodies that interfere with bacterial attachment to erythrocytes. Accordingly, antibodies were effective in the absence of complement and Fc-receptors. Moreover, they formed independently of B-cell hypermutation and isotype class switch. The cloning of neutralizing monoclonal antibodies (mAbs) led to the identification of the bacterial autotransporter CFA as a protective antibody target, and vaccination against CFA protected against Bartonella bacteremia. MAb binding mapped to a region of CFA that is hypervariable in both human- and mouse-pathogenic Bartonella strains, suggesting mutational antibody evasion. These insights further our understanding of Bartonella immunity and immune evasion and elucidate mechanisms driving high Bartonella prevalence in the wild.
