Inducers of Interferon and Host Resistance VII. Antiviral Efficacy of Double-Stranded RNA of Natural Origin

Summary Studies in cell cultures, rabbits, and mice demonstrated the prophylactic and therapeutic efficacy against viral infections and of interferon induction by a variety of double-stranded RNA's of natural origin including fungi, animal, plant, insect, and bacterial viruses. All were found active in microgram amounts. RNA and virus were given by a variety of routes in a number of different regimens including variable drug and virusdosage. The most extensive studies were conducted with double-stranded replicative form RNA from MU9 mutant of MS2 coliphage. Remarkably favorable effects were obtained against PVM, Columbia SK, vaccinia, and parainfluenza 1 virus infections. The polynucleotide was therapeutic in mice when given as late as 2 days following PVM virus, and prophylactic when given as long as 7 days before the virus infection. Preliminary test results showed activity of the DNA-RNA hybrid of the F1 DNA coliphage in inducing interferon and resistance to viral infection.