MAPPING OF ANTIGENIC DETERMINANTS OF THE TRYPANOSOMA-CRUZI HSP70 IN CHAGASIC AND HEALTHY-INDIVIDUALS

In the present paper we describe the analysis of the immunological rec ognition by sera of healthy individuals and chagasic patients of the T rypanosoma cruzi heat shock 70 kDa protein. By a Falcon Assay Screenin g Test, using as antigen an ATP-agarose purified T. cruzi hsp70, it ha s been found that the sera of infected patients as well as of that of healthy individuals show reactivity against the hsp70 protein but that the reactivity of the sera of patients is in general significantly hi gher than that of healthy individuals. The analysis of the reactivity of the chagasic sera against a collection of peptides covering 92% of the protein has shown that more than 50% of the peptides gave a positi ve response but only against a few peptides did we observe high reacti vity in a wide spectrum of sera. Only four peptides (numbers 9, 12, 14 and 47) were recognized by all sera tested with high reactivity value s. The sera of healthy individuals also showed reactivity against a la rge percentage of peptides but with lower values. It was observed that particular peptides showing high reactivity against the sera of healt hy donors also show high reactivity against patients' sera. However, t he general pattern of reactivity against the peptides is different in chagasic and healthy sera. The immunodominant peptides map in the high ly conserved as well as in the less conserved part of the hsp70 molecu le. The 1/3 C-terminal, being the least conserved part of the molecule , seems to be the least immunogenic. Mapping of the epitopes led to th e identification of particular immunogenic motifs within individual pe ptides.