Cloning of a Partial Length cDNA Encoding the C-Terminal Portion of the 75-77-kDa Antigen of Trypanosoma cruzi

ABSTRACT It has been suggested that several Trypanosoma cruzi antigens have possible protective epitopes which may be suitable vaccine candidates. We found previously that animals resistant to T. cruzi infection produced antibodies against the 75-77-kDa parasite antigen. To test the ability of the recombinant form of this antigen to protect animals from T. cruzi infection, the cDNA which encodes a portion of the 75-77-kDa antigen was cloned using a cDNA library constructed in an orientation-specific bacteriophage expression vector (λgt11) from poly (A)⁺ RNA of Brazil strain epimastigotes. One clone, named SFS-40, was selected by screening the library using affinity purified antibodies specific for the 75-77-kDa parasite antigen as probe. The cDNA corresponding to the 1.7-kilobase insert of SFS-40 was subcloned into plasmid vectors and characterized. The cDNA sequence encodes a polypeptide of about 40 kDa. The putative product of the cDNA was homologous to members of the 70-kDa stress protein family. When epimastigotes were shifted from 29° C to 37° C, there was no change in the level of SFS-40 mRNA. In contrast, the 70-kDa heat shock protein mRNA of the parasite was increased about four fold by this treatment.