Debaki R Howlader
National Institute of Cholera and Enteric Diseases, India
Title: Bivalent outer membrane vesicles based immunogen of S. typhi and Paratyphi A induce adaptive immunity and protective effi cacy in mice
Biography
Biography: Debaki R Howlader
Abstract
Salmonella typhi and Salmonella Paratyphi A are the leading causative agents of enteric fever which causes morbidity and mortality worldwide. In this paper, we are focusing on the development of a novel bivalent typhoidal outer membrane vesicles (OMVs) based immunogen against enteric fever. We have isolated Salmonella typhi and Paratyphi A OMVs and also characterized OMVs associated antigens. Then we immunized the adult mice with three doses of our newly formulated bivalent immunogen orally (25 mg/200 ml). After three doses of oral immunization, we found our immunogen can significantly induce humoral response; LPS, Vi-polysaccharide specific serum IgG, IgA, IgM as well as induce Th1 and Th17-cell mediated immunity. We also found bivalent OMVs immunization can prevent heterologous Salmonella strains mediated systemic infection in adult mice model. We determined that the protective immune responses depend on the humoral and cell-mediated immune response. Furthermore, we have evaluated the mode of protective immune response which was carried out by anti-OMVs antibody by significantly inhibiting bacterial motility and mucin penetration. Taken together these findings suggest our bivalent immunogen could be used as a novel candidate vaccine against enteric fever.