engleski

Francisella tularensis DsbA deletion mutant:A possible candidate for live attenuated vaccine against tularemia?

Francisella tularensis, the causative agent of severe disease tularemia, is highly infectious intracellular pathogen. However, there is no licensed vaccine available up today. To move a step closer to the vaccine we carried out a comparative proteomic analysis of different F. tularensis strains. We identified and characterized a homolog of disulfide oxidoreductase family, DsbA, as a potential candidate involved in F. tularensis virulence. We found out that the dsbA mutant is highly attenuated in in vitro and in vivo system. Furthermore, the dsbA mutant was able to elict protective immunity against virulent F. tularensis strain. Using the confocal laser scanning microscopy we characterized the intracellular fate of the dsbA mutant inside primary murine bone marrow derived macrophages. Our results showed that following uptake, the dsbA mutant enters the endocytic pathway and is found in the phagosomes that are characterized by the presence of the early (EEA-1) and the late (LAMP-1) endosomal markers. Subsequently, we showed that the dsbA mutant partially interacts with degradative lysosomal pathway, indicating possible presentation of bacterial antigens into the host cell cytosol and exhibits rapid replication. The ongoing work is aimed at elucidation of the protective mechanisms in both in vivo and in vitro systems. Particularly, the co-localization studies with the host cell MHCII compartment as well as with the autophagosome-like vacuole, and in vivo quantitation of the cytokine response to vaccination with the dsbA mutant are being performed.

DsbA; tularemia; mice

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