Studies of the biosynthesis of protein and ribonucleic acid in HeLa cells infected with poliovirus.

The amounts of protein, RNA (ribonucleic acid), virus, and the rate of incorporation of Pa* into RNA were determined in various subcellular fractions of HeLa cells at various times during a single sequence of infection with poliovirus. From these data interpretations are drawn concerning the biosynthesis at the cellular level of protein and RNA which are induced by virus infection. Within 1 hour after the initiat,ion of infection, there is a detectable accumulation in the cellular cytoplasm of newly synthesized protein and RNA. The synt,hesis of protein continues at a constant rate until the seventh hour of infection. RNA in the cytoplasm increases at a constant rate until the fourth hour, at which time the rate is markedly enhanced, and the first, virus, as infectious activity, appears in the cytoplasmic fraction. The synthesis of RNA stops by the sixth hour. Virus accumulates at an increasing rate in the cytoplasm between the fourth and seventh hours. At the seventh hour, 99% of t)he virus formed is present in the intracellular state. From the amounts of nucleic acid and protein produced, their distribution relative to virus among the various subcellular fractions, and from the nucleotide composition of the RNA, it was concluded that the major portion of the newly formed materials was not virus.