Bivalent DNA Vaccination with Genes Encoding Leishmania major Cysteine Proteinases Type I and II Protects Mice Against Infectious Challenge

Abstract

Cysteine proteinases (CPs) of Leishmania are considered to be attractive vaccine candidate in which their<br />immunogenicity and immuno-modulatory effects have been confirmed. We have previously reported that a<br />cocktail of two DNA plasmids encoding Leishmania major cysteine proteinases type I (CPB) and type II<br />(CPA) induces a partial protective response in murine model of cutaneous leishmaniasis. The results also<br />showed that the induced protective response was better than the responses given by each one the plasmids<br />alone. However, in view of the capability of DNA plasmid for encoding several antigens, we investigated the<br />possibility of using a single bivalent DNA vaccine, based on CP genes as an alternative mean of inducing<br />protective immunity. Here we present evidence favoring that CPA and CPB delivered in the same plasmid<br />DNA backbone either in separate locus or as a tandem fused gene induce partial protection against<br />Leishmania major infection in susceptible BALB/c mice. Immunization of mice with these constructs promoted<br />specific T-cell response of Th1 phenotype that is characterized by an increase in production of IFN-γ.<br />Our results confirm the previous observation about the possibility of DNA immunization against leishmaniasis<br />using CP genes and lend support to the idea of using a single polyvalent plasmid DNA construct to elicit<br />immune responses to several distinct antigens.