Background
The development of an effective vaccine against visceral leishmaniasis (VL) caused by Leishmania donovani is an essential
Conclusion
This comparative study reveals greater effectiveness of the liposomal vaccine for protection against progressive VL in BALB/c. Again, evaluation of the immune responses by vaccination emphasizes the need of stimulation of potent cellular immunity based on both Th1 and Th2 cell responses to confer protection against VL.
Results
All the three formulations afforded significant protection against L. donovani in both the visceral organs, liver and spleen. Although comparable level of protection was observed in BCG+LAg and MPL-TDM+LAg immunized mice, highest level of protection was exhibited by the liposomal LAg immunized group. Significant increase in anti-LAg IgG levels were detected in both MPL-TDM+LAg and liposomal LAg immunized animals with higher levels of IgG2a than IgG1. But BCG+LAg failed to induce any antibody response. As an index of cell-mediated immunity DTH responses were measured and significant response was observed in mice vaccinated with all the three different formulations. However, highest responses were observed with liposomal vaccine immunization. Comparative evaluation of IFN-gamma and IL-4 responses in immunized mice revealed that MPL-TDM+LAg group produced the highest level of IFN-gamma but lowest IL-4 level, while BCG+LAg demonstrated generation of suboptimum levels of both IFN-gamma and IL-4 response. Elicitation of moderate levels of prechallenge IFN-gamma along with optimum IL-4 corresponds with successful vaccination with liposomal LAg.