Effects of Poly I-C on the Course of Infection with Trypanosoma cruzi

Results are presented on the effect of double-stranded Poly I-C upon infections with the intracellular parasite T. cruzi. The ip administration of 300 μg of Poly I-C previous to the inoculation of 1.25 × 103, 1.25 × 102, 1.25 × 101, and 1.25 mouse LD50 of the parasite, followed by doses of 100 fig, 3 times a week for 3 weeks, did not affect the lethality of the infection. On the contrary, the animals in the untreated groups survived by several days those of the treated groups and parasitemia and tissue invasion was of a lower order in the untreated groups. Similar negative results were observed in tissue cultures treated with 100 μg/ml of Poly I-C and infected with 103 TCID50 of T. cruzi. It is interesting to note that doses of Poly I-C as high as 500 μg/ml did not affect the growth rate of T. cruzi in the in vitro culture medium, and that its infectivity was unaltered.