Enteroviral Ribonucleic Acid I. Recovery from Virus and Assimilation by Cells* by John

Recognition of the infectivity of ribonucleic acid (RNA) of tobacco mosaic (1, 2) and of animal virus (3) initiated investigation of the molecular aspects of viral reproduction. Study of replication of infectious RNA depends upon employment of efficient and reproducible biological assay procedures. Reception of viral genetic material normally depends upon specific interaction of cellular and viral receptors (4--6) while phenol extracted virus has lost this specificity (7). Therefore, assay of infectious RNA may require extracellular environments different from those suitable for assay of whole virus. Plaque formation of infectious RNA was greatly improved by use of 1 sodium chloride solution as described by Alexander et al. (8), but considerable variation among enteroviral RNA titers was noted when different RNA preparations were tested in a number of established human cell strains. The general procedure of Gierer and Schramm (1) consistently yielded infectious poliovirus RNA and minor alterations in the extraction procedure were ineffective. Much of the inefficiency of viral RNA action apparently results from failure to introduce RNA into replicating sites of cells. This paper reports factors affecting the biological activity of enteroviral RNA, and a plaque assay system that has proved sensitive and reproducible. Production of infectious RNA from highly purified poliovirus is reported, in confirmation of the observations of others (9, 10), and evidence is presented that only a small fraction of total extracted virus RNA is adsorbed to cells, and is responsible for infectivity.