During canine leishmaniasis a protein belonging to the 83-kDa heat-shock protein family elicits a strong humoral response

By screening of a Leishmania infantum expression library with the serum from a dog affected with visceral leishmaniasis, a cDNA clone with seqeence homology to the Hsp83 gene family was isolated. From analysis of the genomic distribution of the cDNA sequence, it was estimated that the L. infantum genome contains 7 Hsp83 genes tandemly organized. The full-length coding region of the Hsp83 gene located at the 5′-end of the cluster was determined. The deduced amino acid sequence of thee L. infantum Hsp83 shiws a high level of sequence identity with members of the Hsp83ʹs protein family from other eukaryotic organisms. The complete protein (LiHsp83) and 4 subfragments (LiAl, LiBl, LiCl and LiDl) were expressed in Escherichia coli as recombinant proteins and used as target antigens in FAST-ELISA assays against a collection of sera from dogs with visceral leishmaniasis. Ninety percent of the sera recognized the recombinant LiHsp83, indicating that L. infantum Hsp83 is a potent immunogen during canine leishmaniasis. Serological analysis of the recombinant subfragments identified the LiBl subfragment, from amino acid 156 to 283, as the immunodominant region of the protein. This region, which is the less evolutionary conserved region of the protein, was recognized by 88% of the visceral leishmaniasus sera. The results suggest that L. infantum Hsp83 and particular protein subfragments may be useful in serodiagnostic assays for canine leishmaniasis.