Trypanosoma cruzi: isolation of an immunodominant peptide of TESA (Trypomastigote Excreted-Secreted Antigens) by gene cloning.

Trypomastigote forms of Trypanosoma cruzi excrete-secrete several molecules, which are immunodominant during the human infection. This complex antigenic mixture termed TESA (Trypomastigote Excreted-Secreted Antigens) presents a 150-160 kDa band that shows excellent specificity and sensitivity in Chagas' disease diagnosis by immunoblotting. Here we describe the isolation and the antigenic characterization of a recombinant peptide (TESA-1) containing a 10 kDa T. cruzi peptide that belongs to the 150-160 kDa TESA fraction. The clone was isolated by screening a T. cruzi genomic expression library with chagasic antibodies reactive to the 150-160 kDa band of TESA immunoblots. After expression, the recombinant peptide TESA-1 was purified and used to immunize rabbits. Anti-TESA-1 immunesera specifically recognized the 150-160 kDa fraction of TESA-blots from eight different T. cruzi strains. The TESA-1 peptide reacted with 82.2% of chagasic patient sera by immunoblotting, showing that it harbors most of the antigenic epitopes that account for the high reactivity of the 150-160 kDa band of TESA.