Journal of Vaccines & Vaccination

Identifi cation of novel Leishmania donovani antigens for development of second generation vaccine against Leishmaniasis

International Conference & Exhibition on Vaccines & Vaccination

22-24 Nov 2011 Philadelphia Airport Marriott, USA

Sudipta Bhowmick and Nahid Ali

Scientific Tracks Abstracts: J Vaccines Vaccin

Abstract:

Visceral leishmaniasis (VL), caused by the intracellular parasite Leishmania donovani is a major public health problem in the developing world. But there is no eff ective and safe vaccine approved for clinical use against any form of leishmaniasis. Th rough reactivity with kala-azar patient and cured sera, polypeptides ranging from 91 to 31-kDa from L. donovani promastigotes were previously identifi ed as potential protective vaccine candidates. In this study four polypeptides 91(LD91), 72 (LD72), 51(LD51) and 31 (LD31)-kDa were purifi ed from leishmanial antigens (LAg) using sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by electroelution. Another peptide of 36-kDa (LD36) was purifi ed in its native form using soluble leishmanial antigens (SLA) as a source. We compared the vaccine effi cacy of these antigens encapsulated in cationic liposomes in BALB/c mice against challenge infection with L. donovani. Our results demonstrated that liposomal LD31 (74%-77%), LD36 (79%-81%) and LD51(72%-75%) vaccination reduced parasite burden to the greatest degree followed by liposomal LD72 (65%-67%) and LD91 (46%-49%). Analysis of cytokines in protected mice revealed induction of Th 1 cytokines IFN- γ with IL-12 with a down-regulation of Th 2 cytokines IL-4 along with immunosuppressive IL-10, hinted toward a Th 1 polarized immune response instrumental for protection. Th e 31, 36, 51 and 72-kDa bands were identifi ed as ATP synthase chain, Elongation factor-1α, β-tubulin and heat shock 70-related protein 1 precursor of Leishmania, respectively using matrix-assisted laser desorption ionization�time of fl ight (MALDI-TOF/TOF) mass spectrometry. Th ese four leishmanial antigens have not been described before as successful vaccine candidates examined against in vivo VL model. Th us, these antigens can be potential components of a future second generation antileishmanial vaccine.