Immune response to recombinant Leishmania infantum lipophosphoglycan 3 plus CpG oligodeoxynucleotides in BALB/c mice

Development of a protective antileishmanial vaccine is an urgent priority for successful control of different forms of leishmaniasis. The potential of a recombinant lipophosphoglycan 3 (rLPG3) expressed by Leishmania tarentolae was evaluated in combination with CpG oligodeoxynucleotides (CpG-ODN) as a Th1-promoting adjuvant against Leishmania infantum infection in BALB/c mice. First, mice were immunized subcutaneously with rLPG3 either alone or in combination with CpG-ODN. Next, the immunogenic and protective efficacies of this vaccine were analysed in immunized mice. It was observed that coadministration of rLPG3 with CpG-ODN led to enhance in a Th1 response to rLPG3 induced by itself as the IFN-gamma production was promoted in association with the predominant presence of IgG2a antibodies in the sera. However, immunization with rLPG3 plus CpG-ODN induced partial protection against infectious challenge in BALB/c mice. Taken together, further studies are required to improve the protective efficacy using either more potent immune enhancers or vaccination strategies.