Effects of poly(2'-O-methyladenylic acid) on susceptibility and autogenous immunity to RNA tumor virus oncogenesis in vivo.

Poly(2'-O-methyladenylic acid) [poly(Am)] inhibited tumor development and death induced by the Moloney sarcoma virus-leukemia virus complex in newborn mice. The compound was effective at 10 mug per mouse when given at least 1 hr before inoculation of virus, but the greatest inhibition was seen in mice treated at least 4 hr before infection. Poly(2'-O-methyluridylic acid) and poly(vinyladenine) also inhibited sarcoma development and death but were less effective than poly(Am). Poly(Am) also enhanced the antibody response of newborn mice to endogenous leukemia virus envelope antigens, which we refer to as autogenous immunity. The results of these preliminary studies suggest that poly(Am) altered the oncogenic potential of the Moloney sarcoma-leukemia virus complex in vivo, and the effect appears to be mediated through an enhancement of the immune response of the treated animals.