CLONING OF A PARTIAL LENGTH CDNA-ENCODING THE C-TERMINAL PORTION OF THE 75-77-KDA ANTIGEN OF TRYPANOSOMA-CRUZI

It has been suggested that several Trypanosoma cruzi antigens have pos sible protective epitopes which may be suitable vaccine candidates. We found previously that animals resistant to T. cruzi infection produce d antibodies against the 75-77-kDa parasite antigen. To test the abili ty 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 ant igen was cloned using a cDNA library constructed in an orientation-spe cific bacteriophage expression vector (lambda gt11) from poly (A)(+) R NA of Brazil strain epimastigotes. One clone, named SFS-40, was select ed by screening the library using affinity purified antibodies specifi c 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 vector s 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 degrees C to 37 degrees C, there was no change in the level of SFS -40 mRNA. In contrast, the 70-kDa heat shock protein mRNA of the paras ite was increased about four fold by this treatment.