[Stimulating effect of cellular RNA on the in vitro polymerizing activity of influenza virus ribonucleoprotein]

The stimulating effect of RNAs isolated from noninfected and influenza virus-infected chick fibroblasts on the polymerase activity of influenza virus intracellular ribonucleoprotein (RNP) was studied in vitro. The infected cells were shown to contain two classes of RNAs which stimulated well the polymerase activity of influenza virus RNP. One class seemed to be represented by a heterogenous cellular 10-20 S mRNA since it contained poly (A)-sequences and was present in noninfected cells. The other RNA class was induced during the infection and differed in number of properties from the RNA isolated from noninfected cells. This class RNA was smaller (4-10 S) and appeared not to contain poly(A)-sequences. Treatment of both noninfected and infected cells with actinomycin D resulted in inhibition of synthesis of both classes of RNA-primers.