Cross-protection against Leishmania donovani but not L. Braziliensis caused by vaccination with L. Major soluble promastigote exogenous antigens in BALB/c mice.

Vaccinating with soluble Leishmania major promastigote exogenous antigens (LmSEAgs) protects mice against challenge with L. major. To explore the potential of LmSEAgs to cross-protect against infection with other species of Leishmania, BALB/c mice were immunized with LmSEAgs prior to challenge with either L. donovani or L. braziliensis promastigotes. Such mice were protected against L. donovani but not L. braziliensis infection. Leishmania braziliensis-infected mice developed lesions that were not significantly different from those of controls and that contained 13-fold more parasites. In contrast, immunized mice infected with L. donovani were protected as illustrated by low splenic parasite loads (as much as 4,913-fold fewer parasites). This protection corresponded to significant increases in gamma interferon and low production of interleukin-4 (IL-4) IL-4 or IL-10, which suggested an enhanced type 1 response.