THE HSP60 GENE OF THE HUMAN PATHOGENIC FUNGUS COCCIDIOIDES-IMMITIS ENCODES A T-CELL REACTIVE PROTEIN

A heat shock protein-encoding gene (hsp60) from the human respiratory fungal pathogen, Coccidioides immitis (Ci), was cloned, sequenced, chr omosome-mapped, expressed and immunolocalized in parasitic cells. Both the genomic and cDNA sequences are presented. The transcription start point and poly (A) addition site were confirmed. The hsp60 gene conta ins two introns and a 1782-bp ORF which translates a 594-amino acid (a a) protein of 62.4 kDa and pI of 5.6. The translated protein revealed two potential N-glycosylation sites. The deduced HSP60 showed 78-83% a a sequence similarity to reported fungal HSP60 proteins. The hsp60 gen e was mapped to chromosome III of Ci and was shown to be a single copy gene by Southern and Northern hybridization. Expression of a 1737-bp cDNA fragment of the hsp60 gene in E. coli resulted in production of a recombinant protein. Amino acid sequence analysis of the recombinant protein confirmed that it was encoded by the Ci hsp60 gene. Antiserum raised in mice against the isolated recombinant protein immunolocalize d HSP60 in the cytoplasm and wall of parasitic cells of Ci. The recomb inant HSP60 was used to immunize BALB/c mice and was shown to induce p roliferation of T cells isolated from lymph nodes of these animals. Th e hsp60 gene of Ci is the first reported heat-shock protein gene of th is human pathogen. (C) 1997 Elsevier Science B.V.