We propose to develop a recombinant subunit vaccine against cutaneous leishmaniasis. This vaccine will incorporate two protein antigens, TSA/TryP and P-4. Both antigens are highly conserved among Leishmania species, are recognized by T cells of human patients, and confer protection against a live challenge in murine model studies. We expect that immunization using PLGA nanoparticles together with these two proteins will confer protection against disease caused by many of the Leishmania species. Recombinantly expressed TSA/TryP and P-4 proteins will be formulated into PLGA nanoparticles containing one of two adjuvants, namely a CpG oligonucleotide and/or monophosphoryl lipid A (MPLA). Different formulations will be evaluated for immunogenicity and duration of the immune response (memory) in mice. We expect that proteins encapsulated in PLGA particles will elicit long-lasting immune responses. Protection against Leishmania has been shown to be mediated primarily by T-cells, and in particular CD4+/CD8+ T-cells double-positive or triple-positive for IL-2, TNFalpha, and IFN-gamma. We will select the two formulations eliciting the highest proportion responding CD4/CD8 T cells. These two formulations will then be tested for efficacy in two murine models of leishmaniasis. The first model is a challenge with L. major, the main species responsible for leishmaniasis in the Old World. The second model is an infection with L. (Viannia) panamensis, a model for New World leishmaniasis and possibly a more stringent test of vaccine efficacy. In Phase II of this project, we anticipate testing the efficacy of the most promising formulation in non-human primate models of leishmaniasis.
Leishmaniasis is a serious parasitic disease endemic in many subtropical countries. It is estimated that more than 12 million individuals are infected globally and 1-2 million contract the disease annually. Further, hundreds of US military personnel developed leishmaniasis after being deployed in Iraq and Afghanistan;some cases have also occurred in the Southern United States. We propose to develop a vaccine to prevent this disease.