CONICET | Buscador de Institutos y Recursos Humanos

BACKGROUND: The TcTASV is a recently-identified multigene family in T. cruzi that is conserved in the different lineages of the parasite and has no orthologues in other trypanosomatids. The TcTASV-C subfamily is composed by ~15 genes and one of them has been identified among a pool of protective antigens. TcTASV-C is expressed at the surface of trypomastigotes and shed into the medium. However, studies carried out with cell culture-derived trypomastigotes indicated that TcTASV-C is not a major component of the parasite. In the present study we evaluate the expression of TcTASV-C in blood-derived trypomastigotes. METHODS: T. cruzi strains of lineages I,V and VI were used. Infected mice were bled at the peak of parasitaemia and circulating trypomastigotes purified. Trypomastigotes from in vitro cultures were obtained from monolayers of infected Vero cells grown in MEM-4%FBS. Purified blood-derived parasites were used to infect Vero cells. TcTASV-C expression was analyzed by western blot using anti-TcTASV-C antibodies. RESULTS: TcTASV-C is expressed in blood-derived trypomastigotes in all the strains analyzed, in contrast with culture-derived trypomastigotes where TcTASV-C was expressed in few strains. Moreover, the lysate from 10^5 bloodstream parasites was enough to detect its expression, while the equivalent of 2x10^7 parasites was necessary to detect TcTASV-C expression in culture-derived trypomastigotes. When bloodstream trypomastigotes were used to infect cells, the TcTASV-C expression in culture-derived trypomastigotes dropped dramatically after the second in vitro passage. CONCLUSIONS: The expression of TcTASV-C in bloodstream trypomastigotes is 100-fold higher than in culture-derived trypomastigotes, suggesting that a factor present in the host triggers its expression.