The protective effect of the 4-5S immune RNA against Trypanosoma cruzi infection in mice.

The immune RNA (iRNA) was extracted from the spleens of mice infected with Trypanosoma cruzi. The 4-5S iRNA, obtained by sucrose gradient centrifugation, was effective in reducing the parasitemia and mortality of mice challenged with a virulent strain of T. cruzi. No such activity was found in the RNA fraction obtained from the spleens of normal (4-5S nRNA) animals. Mouse peritoneal macrophages exposed to the 4-5S iRNA were able to inhibit the growth of T. cruzi. These results suggest that the protective effect of the 4-5S iRNA against T. cruzi infection could be due to its ability in enhancing macrophage resistance to this parasite.