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 seru m from a dog affected with visceral leishmaniasis, a cDNA clone with s equence homology to the Hsp83 gene family was isolated. From analysis of the genomic distribution of the cDNA sequence, it was estimated tha t the L. infantum genome contains 7 Hsp83 genes tandemly organized. Th e full-length coding region of the Hsp83 gene located at the 5'-end of the cluster was determined. The deduced amino acid sequence of the L. infantum Hsp83 shows a high level of sequence identity with members o f the Hsp83's protein family from other eukaryotic organisms. The comp lete protein (LiHsp83) and 4 subfragments (LiA1, LiB1, LiC1 and LiD1) were expressed in Escherichia coli as recombinant proteins and used as target antigens in FAST-ELISA assays against a collection of sera fro m dogs with visceral leishmaniasis. Ninety percent of the sera recogni zed the recombinant LiHsp83, indicating that L. infantum Hsp83 is a po tent immunogen during canine leishmaniasis. Serological analysis of th e recombinant subfragments identified the LiB1 subfragment, from amino acid 156 to 283, as the immunodominant region of the protein. This re gion, which is the less evolutionary conserved region of the protein, was recognized by 88% of the visceral leishmaniasis sera. The results suggest that L. infantum Hsp83 and particular protein subfragments may be useful in serodiagnostic assays for canine leishmaniasis.