Prime-boost vaccination using Cysteine proteinases type I & II of L. infantum confers protective immunity in murine visceral leishmaniasis

Vaccination with a cocktail of DNA encoding cysteine proteinases has been previously shown to confer protection against experimental cutaneous Leishmaniasis. In the present study we test the efficacy of immunization against L. infantum in a murine model of infection, using a prime-boost strategy. BALB/c mice were immunized twice, in a three weeks interval, with cocktail of plasmids DNA encoding type I (cpb) & II (cpa) cysteine proteinases. DNA immunization was then followed by a boost with rCPA/rCPB in addition to CpG ODN and Montanide720 as adjuvant. Analysis of the immune response showed that vaccination mainly elicited antigen-specific IgG2a antibodies, suggesting the induction of a Th1 immune response. This was further confirmed by the analysis of the splenic cytokine production: at all time points the ratio of IFN-γ/IL-5 induced upon restimulation with rCPA and rCPB was always significantly higher in vaccinated group compared to both control groups.This is the first report where a vaccination confers sterile clearance in a murine model of visceral leishmaniasis.