Differential inhibitory effects of actinomycin D among strains of poliovirus.

Schaffer, Frederick L. (University of California, Berkeley), and Marjorie Gordon. Differential inhibitory effects of actinomycin D among strains of poliovirus. J. Bacteriol. 91:2309-2316. 1966.-Actinomycin D exerted a differential effect on the ability of strains of poliovirus to replicate in HeLa cells. LSc-2ab was studied as an example of a strain markedly inhibited by actinomycin; MEF(1) served as a control strain with minimal inhibition. The effect was noted at an actinomycin concentration of 0.1 mug/ml, but 2.5 mug/ml was used for most studies. Variability in the effect was attributed, in part, to physiological factors. Actinomycin was effective when present during the first 2 hr of LSc infection, but had little effect if present at later times. It did not block adsorption or initiation of ecilpse. It did block synthesis of ribonucleic acid in LSc-infected cells. Several possible modes of action are discussed, the most attractive being that actinomycin blocks synthesis of some cell component, the concentration of which is more critical for replication of some poliovirus strains than others.