INFECTIVITY OF HISTONE-POLIOVIRUS RIBONUCLEIC ACID PREPARATIONS.

Ludwig, Ernest H. (The Pennsylvania State University, University Park) and Christine E. Smull. Infectivity of histone-poliovirus ribonucleic acid preparations. J. Bacteriol. 85:1334-1338. 1963.-Some properties of histone-poliovirus ribonucleic acid (RNA) preparations, as relate to infectivity for HeLa cell monolayers, were investigated. The histone-RNA preparations were found to lose their infectivity rapidly at room temperature. They were considerably more stable at ice-bath temperature. Dilution of a histone-RNA preparation in a diluent containing an appropriate amount of histone yielded a plaque count which was proportional to the dilution factor, and which regressed linearly through the point of origin. Dilution of a histone-RNA preparation in a diluent containing no histone resulted in a rapidly decreasing plaque count which was not proportional to the dilution factor. The ability of histone to enhance the infectivity of poliovirus RNA was found to be dependent upon the presence of a low concentration of a monovalent salt in the histone-RNA preparations. Histone-RNA preparations containing approximately isotonic levels of NaCl exhibited a high degree of infectivity. When concentrations of NaCl outside this range were used, a great loss in infectivity of the histone-RNA preparations occurred. The NaCl could be replaced by KCl but not by CaCl(2), MgCl(2), or MgSO(4).