Influence of organ extracts of Triatoma infestans on differentiation of Trypanosoma cruzi.

The influence that extracts of different T. infestans organs possess to induce Trypanosoma cruzi differentiation from epimastigotes to metacyclic forms in Grace's and modified Grace's media was analyzed. Growth of epimastigotes was adequate in Grace's medium when homogenates of stomach, testes, and ovaries from recently fed insects were added. Growth of epimastigotes was adequate when testes or ovaries obtained from recently fed triatomes were added to modified Grace's medium. Similar results were obtained in Grace's or modified Grace's media supplemented with stomach or intestinal homogenates obtained from "starved" triatomes. None of the above culture conditions induced differentiation of epimastigotes to the metacyclic stage. When extracts of intestine or stomach obtained from triatomes fed 24 to 48 hr previously were used to supplement the modified Grace's medium, growth and differentiation to the metacyclic stage was induced in a high percentage of the population. When extracts of intestine obtained from recently fed insects were used to supplement Grace's medium, differentiation and growth was an in modified Grace's medium. No important differences were observed if cultures were prepared at pH 6.4 or 7.0. The triatome food source did not seem to be important for the differentiation. The parasite population after differentiation to metacyclic type forms showed a higher degree of infectivity than the original population constituted mostly by epimastigotes. These studies suggest the importance of factors from the insect vector in differentiation of T. cruzi.