Molecular, biochemical characterization and assessment of immunogenic potential of cofactor-independent phosphoglycerate mutase against Leishmania donovani: a step towards exploring novel vaccine candidate

Despite immense efforts, vaccine against visceral leishmaniasis has yet not been developed. Karlier our proteomic study revealed a novel protein, cofactor-independent phoshoglycerate mutase (LdiPGAM), an important enzyme in glucose metabolism, in T helper cells type 1 (Th 1) stimulatory region of soluble Leishmania dtmovatii antigen. In this study, LdiPGAM was biochemically and molccularlv characterized and evaluated for its immunogenicity and prophylactic efficacy against L. donovani. Immunogenicity of recombinant LdiPGAM (rLdiPGAM) was initially assessed in naive hamsters immunized with it by analysing mRNA expression of inducible nitric oxide (NO) synthase (iNOS) and other Th1/T helper cells type 2 cytokines, which revealed an upregulation of Thl cytokines along with iNOS. Immunogenicity of rLdiPGAM was further evaluated in lymphocytes of treated Leishmania-'micctcd hamsters and peripheral blood mononuclear cells of Leishmania patients ill clinical remission b}(r) various parameters, viz. lymphoproliferation assay and NO production (hamsters and patients) and levels of various cytokines (patients). rLdiPGAM induced remarkable Lymphoproliferative response and NO production in treated Leishmania-infected hamsters as well as in patients and increase in interferon gamma (IFN-gamma), interleukin-12 (IL-12p40) responses in Leishmania patients in clinical remission. Vaccination with rLdiPGAM exerted considerable prophylactic efficacy (73%) supported by increase in mRNA expression of iNOS, IPN-gamma and 1 L-12p40 with decrease in transforming growth factor beta and interleukin-10. Above results indicate the importance of rLdiPGAM protein as a potential vaccine candidate against visceral leishmaniasis.