Investigations of the antiviral activity of some nitroso-urea derivatives. Inhibitory action of the IOB-252 nitroso-urea derivative on vaccinia virus incell cultures.

The nitroso-urea derivative IOB-252 was administrered in monkey kidney cell cultures in a concentration of 40 mug/ml 24 hours before inoculation of vaccinia virus and maintained afterwards in a concentration of 25 mug/ml. The drug inhibited vaccinia virus multiplication, hemagglutinin synthesis and late cytopathic effect, but did not prevent early cytopathic lesions. IOB-252 inhibited the synthesis of interferon initiated by a viral inductor and blocked the antiviral effect of an exogeneous interferon. The mechanism of action of the drug is discussed.