DNA vaccines induce partial protection against Leishmania mexicana.

As part of an ongoing effort to develop a vaccine against Leishmania mexicana, we tested DNA vaccines encoding L. mexicana GP63, CPb, and LACK, and L. amazonensis GP46, to evaluate this strategy and define the best antigen candidates. Immune responses and vaccine efficacy were evaluated in BALB/c mice immunized with plasmid DNA encoding the different antigens. All four DNA vaccines induced Leishmania-specific humoral and lympho-proliferative immune responses. However, only mice immunized with VR1012-GP46, VR1012-GP63 and VR1012-CPb were partially protected against infection, as evidenced by reduced lesion size and parasite burden. Interestingly, immunization of mice with a mixture of these three plasmids further increased protection. Thus, plasmids encoding CPb, GP63 and GP46 represent good candidates for further development of DNA vaccines against L. mexicana.