Resumen

GRATEROL, Diana et al. The amastigote stadium precedes epimastigote evolution during in vitro Trypasnosoma cruzi epimastigogenesis. Rev. Soc. Ven. Microbiol. [online]. 2013, vol.33, n.1, pp.72-79. ISSN 1315-2556.

Transformation of blood Trypanosoma cruzi tripomastigotes into epimastigotes occurs naturally at the insect gut and is identified as epimastigogenesis. Here we report that during in vitro epimastigogenesis, tripomastigotes transform into rounded forms, biologically and antigenically equivalent to the amastigote stadium, with a persistance time which depends on the height of the culture medium. Tripomastigote forms from cultures of infected tissues were incubated in flasks with different LITB medium heights (3 and 83 mm), and kinetics of transformation to epimastigotes were compared. Masses of parasites at different differentiation times were collected for antigen production. Morphological changes, inoculum increase and resistance to complement were studied by phase contrast microscopy and Giemsa stained smears. Antigenic changes were analyzed through Western Blot using an IgY anti-amastigote antibody. Results showed that rounded forms resist lysis by complement, express amastigote-specific antigens, and that the speed of transformation to epimastigotes depends on the height of the supernatant medium in the culture. Evidences suggest that apart from a temperature fall, a low dissolved oxygen tension and a high parasite per area density accelerate the differentiation process.

Palabras clave : Trypanosoma cruzi; in vitro epimastigogenesis; amastigote-specific antigens.