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

Abstract

We have shown that a member of the 70-kDa heat shock protein (Hsp7O) 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 Hsp7O, 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-Hsp7O response. Purified recombinant L. donovani Hsp7O 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.

B‐cell epitopes of antigenic proteins in Leishmania infantum: an in silico analysis

“…According to Quijada et al (23), the H17 peptide is an immunodominant and species-specific B-cell epitope, as it is different from the equivalent region in the HSP70 of Trypanosoma cruzi. Additionally, the programs predicted one epitope located in the carboxy-terminal region (from Met-525 to Glu-545) identified herein as Ph10, which includes some amino acids residues (EAD-DRA) previously described as immunodominant by Wallace et al (25). Among the 14 linear epitopes predicted, five are above the cut-off point established by Quijada et al (23).…”

“…TDR1 and CP were nor previously reported as antigens and were discovered by our regular screening procedure. On the other hand, the HSP70 protein was used as a prediction control because its epitopes have been experimentally tested by Wallace et al (25) and Quijada et al (23). The three programs predicted the entire region of the H17 epitope (241-260) of L. infantum HSP70.…”

Heterogeneity in heat shock protein genes in Leishmania isolates

“…18 Some of these genes are constitutively expressed while others are inducible and are expressed when the cell is confronted with an exposure to a variety of stimuli or other stress factors. 18,19 Despite the highly conserved nature of stress proteins, a disease-speci®c recognition of L. donovani hsp70 by sera from kala azar patients has been reported 20 and, consistent with this, an immunodominant epitope (EADDRA) has been identi®ed, which is present in the divergent region of the sequence suggesting con®nement of this epitope to the regions of the sequence that are not highly conserved. We could not substantiate this observation using hsp70 antigen.…”

During active viscerocutaneous leishmaniasis the anti-P2 humoral response is specifically triggered by the parasite P proteins

“…Wallace etal. [7] have also described that during Leishmania infection the humoral response against the highly conserved hsp70 protein is also species-specific, in contrast with Chagas' disease in which the reactivity of the patient's sera is directed against both conserved and nonconserved regions of the parasite hsp70 protein [30]. Thus, the difTerences in the selection of epitopes probably reflect the outcomes of infection with two protozoan species causing different diseases, rather than the existence of differences in the immunogenic properties of the highly conserved proteins.…”

“…In fact, high levels of circulating antibodies are produced during the infection, most of which are directed against highly conserved proteins. The hsp70 [6,7], the histone H2A [8], a kinesin-reiated protein [9], and the acidic ribosomal proteins [10,11] have been described as the most Correspondence: Carlos Alonso, Centro de Biologia Molecular 'Severo Ochoa', Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain. prominent antigens.…”