Antiviral action of 5-bromo-2'-deoxyuridine and polyoma virus-specific RNA synthesis

The influence of 5-bromo-2'-deoxyuridine on the synthesis of polyoma virus-specific RNA in mouse embryo cells at a late phase of infection was assayed by molecular hybridization. The effect of the analogue on virus yields in terms of infectivity (p.f.u.) and haemagglutination activity (h.a.u.) was also quantitated. 12.68-126.80 micrograms/ml bromodeoxyuridine inhibited viral RNA synthesis to 15-10%, h.a.u. titers of virus yield to 50-10%, p.f.u. titers of virus yield to 0.10-0.01%, and p.f.u./h.a.u. ratios to 1.0-0.1% of the respective controls. The inhibition of viral RNA synthesis was reversed by thymidine. Since i) bromodeoxyuridine inhibited viral RNA synthesis and h.a.u. titers only partially and to a different extent, and ii) it reduced p.f.u. titers and p.f.u./h.a.u. ratios by several orders, it is likely that viral RNA synthesis represents only one of the sites of the antiviral action of the analogue.