SERUM ANTIBODIES TO TRYPANOSOMA-CRUZI ANTIGENS IN ATACAMENOS PATIENTSFROM HIGHLAND OF NORTHERN CHILE

In the present work we have investigated the serum antibody spectrum t o parasite antigens involved in human T. cruzi infection. Analysis was performed by conventional serology (IHA, IFAT and ELISA), complement- mediated lysis, anti-gal antibody assay and reactivity against recombi nant and synthetic peptides and metacyclic antigens by immunowestern-b lotting. All the sera showed a significant reactivity in IHA, IFAT and ELISA. We found that 84.2% of the sera showed lytic activity and thir ty serum samples (78.9%) which showed a lytic activity higher than 50% , also showed anti-gal antibodies at serum dilutions higher than 1:1,6 00. Ninety-four percent of sera reacted with one or more of the recomb inant DNA clones and 97.3% reacted with one or more of the synthetic p eptides. A pool of serum samples with a lytic activity higher than 75% were able to produce 60% to 78% inhibition of cell invasion. Thirty-s ix of the serum samples (94.7%) were able to react by immunowestern bl otting with a T. cruzi metacyclic antigen with molecular size of 70 kD a. The results obtained give preliminary information about the humoral immune response and the possible role of antibodies in protection aga inst T. cruzi infection of chronic patients from the highlands of Chil e.