Metacyclic neutralizing effect of monoclonal antibody 10D8 directed to the 35- and 50-kilodalton surface glycoconjugates of Trypanosoma cruzi

It was shown in this work that the infectivity of metacyclic forms of Trypanosoma cruzi was affected upon interaction with the monoclonal antibody (10D8), which reacts with a carbohydrate epitope of the 35- and 50-kilodalton (kDa) surface glycoconjugates. The invasion of Vero cells by metacyclic forms of strains Tulahuen and G was inhibited 50 to 67% in the presence of 10D8 (10 micrograms/ml), whereas a nonrelated monoclonal antibody to Plasmodium berghei had no such effect. In mice that were inoculated with metacyclic forms preincubated with 10D8 or that had passively received 10D8 before challenge with metacyclic forms, a considerable decrease in the parasitemia levels was observed. The 35- and 50-kDa antigens were detectable by the galactose oxidase and sodium boro[3H]hydride procedure but not by surface iodination or metabolic labeling with [35S]methionine, suggesting that they may be of glycolipid nature. The finding that the 35- and 50-kDa antigens are major bands recognized by sera of mice immunized with killed metacyclic forms and protected against acute infection, in addition to the results with 10D8, indicate that these glycoconjugates may play an important role in the metacyclic form-host cell association that initiates T. cruzi infection.