Studies on the mode of action of single-stranded polynucleotides which are antiviral against encephalomyocarditis virus infection of mice.

Poly(dI) and poly(dC) administered separately or sequentially show no antiviral effects against EMC virus infection of mice, whereas poly(rI) and poly(rC) are antiviral in such treatment regimens without evidence of interferon induction. The antiviral effects of poly(rI) and poly(rC) appear to depend on single-strandedness because their antiviral effects are decreased by annealing to poly(dC) and poly(dI) respectively. This decrease in antiviral effect would not seem to be due to an adverse effect of polydeoxyribonucleotides on EMC virus infection because the polydeoxyribonucleotides have no effect on the antiviral activity of another single-stranded RNA, E. coli tRNA.