Cordycepin Inhibits Induction of Murine Leukovirus Production by 5-iodo-2′-deoxyuridine

Cordycepin (3′-deoxyadenosine), an inhibitor of poly(A) synthesis during the processing of nuclear heterogenous RNA, blocks the production of RNA viruses induced by 5-iodo-2′-deoxyuridine in BALB/3T3 and BALB/K-3T3 cells. This inhibitory activity is not a result of either nonspecific cell killing or general cytotoxicity by cordycepin; rather, it appears to be specific, because cordycepin acts only at a critical time to inhibit virus production. These findings, together with the finding of poly(A) sequences in viral RNAs, suggest that RNA tumor viruses replicate via a transcription of proviral DNA.