Mapping of a visceral leishmaniasis-specific immunodominant B-cell epitope of Leishmania donovani Hsp70.

We have shown that a member of the 70-kDa heat shock protein (Hsp70) family is a major target of the humoral immune response during Leishmania donovani infection. A recombinant fusion protein was recognized by sera from 92% (35 of 38) of patients with visceral leishmaniasis, including representatives from each of the major regions where it is endemic. Serological analysis of recombinant Hsp70, expressed by a series of deletion constructs, identified the carboxy-terminal region as the immunodominant site. This region, which is the most evolutionarily divergent part of the molecule, was recognized by all sera from patients with visceral leishmaniasis which exhibited an anti-Hsp70 response. Purified recombinant L. donovani Hsp70 was not recognized by sera from patients with cutaneous leishmaniasis, Chagas' disease, leprosy, malaria, or schistosomiasis. To determine the regions involved in antibody recognition, a series of overlapping peptides were synthesized on polyethylene pins by the Pepscan method, and a hexamer, EADDRA, was identified by the visceral leishmaniasis serum samples as an immunodominant B-cell epitope.