Vaccination with the divergent portion of the protein histone H2B of Leishmania protects susceptible BALB/c mice against a virulent challenge with Leishmania major.

To identify approaches for vaccination against leishmaniasis, we analyzed the protective effect of different constructions using recombinant peptides from the protein Leishmania (L.) major histone H2B. H2B sequence displays two distinct regions: an amino-terminal region divergent from mammalian H2B (27% identity) and a carboxy-terminal region highly conserved with mammalian H2B (55% identity). We tested the ability of the entire H2B protein, its divergent or conserved regions to provide protection against virulent L. major challenge. While the recombinant H2B protein adjuved with CpG induces potent cellular and antibody responses when injected to BALB/c mice, only the divergent amino-terminal region of H2B is able to confer potent protection against a virulent challenge. These findings indicate that different portions of the same parasite protein may express contrasting protective effects likely through the induction of different effector mechanisms. Due to its potent protective properties in the BALB/c mouse model, the amino-terminal region of Leishmania H2B could constitute a good vaccine candidate.