Leishmania infantum: Gene cloning of the GRP94 homologue, its expression as recombinant protein, and analysis of antigenicity

The complete nucleotide sequence for the Leishmania infantum homologue to t he glucose-regulated protein 94 (GRP94) gene was determined from the isolat ion and characterization of a genomic clone. Like the mammalian and plant G RP94s, the L. infantum GRP94 sequence possesses both an N-terminal signal p eptide and a putative endoplasmic reticulum retention signal, consisting of the C-terminal tetrapeptide EDDL. Thus, L. infantum is the first protozoan organism in which GRP94 has been identified. Southern blot analysis has in dicated that this protein is encoded by a single-copy gene. The L. infantum GRP94 gene was expressed in Escherichia coli and the recombinant protein u sed to evaluate its antigenicity and immunogenicity. Eighty-four percent of sera from dogs with visceral leishmaniasis reacted with the protein, indic ating that GRP94 is a potent immunogen during Leishmania infection. Given t he immunogenic and antigenic properties shown by the L. infantum GRP94, we think that this protein constitutes a valuable molecule for diagnostic purp oses and a potential candidate for studies of protective immunogenicity. (C ) 2000 Academic Press.