The Assay, Extraction and Storage of Infective Ribonucleic Acid from Foot and Mouth Disease Virus

Abstract

SUMMARYA plaque assay method is described for the titration of the infective ribonucleic acid (RNA) of foot-and-mouth disease (FMD) virus. The method depends on the dilution of the RNA in salt solutions of high molarity and the treatment of the BHK 21 cell monolayers used with M-NaCl. The method is reproducible and is a t least as sensitive as other methods of titration. The extraction of RNA in the presence of EDTA gave titres corresponding to 0*1% of the titre of the intact virus. RNA prepared from virus suspensions containing EDTA retained about 50 yo of initial infectivity for 7 days at 4' but for longer periods it was best preserved in 70 % (v/v) ethanol at -20' .