Aspects of the synthesis of poliovirus RNA and the formation of virus particles

Abstract

In HeLa cells, poliovirus RNA synthesis begins within an hour after infection and continues exponentially for 3 hours, the rate becoming linear at this time. Up to 2 hours of infection, none of the RNA which has been made has entered virus particles but is found in polyribosomes. After 2.5 hours, RNA begins also to be enclosed within virus particles, and by 4 hours, 20% of the total RNA which has been synthesized is in virus. At 3.75 hours of infection, an RNA molecule can be coated with viral protein within less than 5 minutes after its synthesis, and this coating can take place in the absence of protein synthesis. Conclusions drawn from these data are: (1) The concept of an “eclipse phase” for poliovirus is valid only in terms of virus particle formation. Virus RNA synthesis commences very early after infection. (2) The templates responsible for viral RNA synthesis multiply during the early stage of infection. The exponential rise in RNA synthesis is not due simply to asynchrony of activation of template precursors among the input molecules. (3) There exists in the infected cell a pool of viral coat-protein precursors. All the protein for a given virus particle can be synthesized prior to its RNA.