Induction of Th1-type cellular responses in cured/exposed Leishmania-infected patients and hamsters against polyproteins of soluble Leishmania donovani promastigotes ranging from 89.9 to 97.1 kDa.

Earlier, we have identified soluble antigenic fraction ranging from 68 to 97.4 kDa (F2-fraction) of Leishmania donovani promastigote, which induced Th1-immunostimulatory cellular responses in both cured Leishmania patients/hamsters and exhibited significant prophylactic potential against experimental visceral leishmaniasis (VL). In the present study, we have further fractionated F2-fraction by continuous elution SDS-PAGE and subjected them to re-evaluation for their ability to induce cellular responses. Out of seven sub-fractions: F2.1-F2.7, only four F2.4-F2.7 (89.9-97.1 kDa), individually or in pooled sub-fractions (P4-7), stimulated Th1-type remarkable lymphoproliferative, NO, IFN-gamma and IL-12 responses in Leishmania-infected cured/exposed patients and hamsters. Interestingly, optimum Th1-responses were obtained with P4-7 suggesting the presence of immunostimulatory molecules in it and may be exploited for developing a successful subunit vaccine against VL.