Increased serum levels of an interferon-like activity during the acute period of experimental infection with different strains of Trypanosoma cruzi.

A marked development of an interferon-like antiviral activity was observed in the serum of mice infected with Tulahuén strain Trypanosoma cruzi as early as 24 hours after infection with 500 parasites. Such activity remained elevated until 48 hours postinfection and was reduced to undetectable levels--characteristic of normal, uninfected animals--by 72 hours. Infection with 10(4) Tulahuén strain T. cruzi resulted in production of somewhat lesser levels of interferon activity detectable 12 and 24 hours postinfection but not after 48 hours. Infection with 500 parasites of the Y strain was also followed by an increased interferon-like activity but this was not detectable until day 2 postinfection. During the chronic phase of the disease, interferon-like activity levels were indistinguishable from those of uninfected animals. The possibility that interferon activity may have a regulatory effect on the course of the infection is discussed.