Montanide ISA 720 is more effective than BCG as an adjuvant for Leishmania killed vaccine in BALB/c mice

The aim of this study was to evaluate the immunogenicity and efficacy of Montanide ISA 720 against BCG and alum as an adjuvant for Leishmania killed vaccine in BALB/c mice. Groups of mice were immunized with either, Baccile Calmette Guerin (BCG), aluminium hydroxide (alum) or Montanide ISA 720 (MISA) with killed Leishmania major (KLM) promastigotes antigen and later, sacrificed or challenged with virulent promastigotes. Vaccination with alum-KLM and BCG-KLM produced higher IgG responses than vaccination with Montanide ISA-KLM. Significantly higher lymphoproliferative response was obtained for the MISA-KLM mice than in both the alum-KLM and BCG-KLM vaccinated mice. The BCG-KLM group produced the highest interferon gamma (IFN-γ) while the alum-KLM gave the least IFN-γ responses. Among the three adjuvants, BCG vaccination recorded the biggest lesion sizes, an indication of adverse reaction by BCG while the MISA 720 vaccinated mice showed the smallest cutaneous lesions. There was a good correlation between parasite burden and IFN-γ level indicating IFN-γ response as a sensitive parameter of immune response to the vaccine antigen used. The findings suggest MISA-KLM as a safe and effective immunization against cutaneous leishmaniasis but suggests for confirmation of the results in non-human primate model before clinical trials in humans.