Characterization of the antiviral activity produced during Trypanosoma cruzi infection and protective effects of exogenous interferon against experimental Chagas' disease.

Mice infected with Trypanosoma cruzi have been shown to develop an antiviral activity in their sera as early as 24 hr postinfection. This activity was characterized in this work as alpha/beta interferon by the following criteria: resistance to pH 2 treatment, sensitivity to incubation at 56 C, or to trypsin treatment, or to actinomycin D treatment, and inactivation by antibody specific for alpha/beta interferon produced in L cells. Mice receiving exogenous alpha/beta interferon in seven daily doses starting on the day of infection with T. cruzi displayed an enhanced resistance evidenced by significantly decreased parasitemias with respect to those of infected animals receiving a mock preparation lacking interferon activity. Direct incubation of T. cruzi with interferon had no consequence on the motility, infectivity or virulence of the parasite. These results suggest a possible role for interferon in inducing enhancement of host resistance against T. cruzi infection.