Foot and mouth disease virus I. Stability of its ribonucleic acid

A variable amount (30–90%) of fragmented molecules have been reported when the foot and mouth disease virus (FMDV) RNA is analyzed with different methods. In an attempt to find clues for this characteristic heterogeneity, FMDV-RNA was isolated from virions purified by two different methods. One of the methods, a variant of the usual purification procedure, rendered heterogeneous RNA molecules; with the other method, a shortened procedure, the results were strikingly different and the purified RNA proved to be homogeneous, even when submitted to different denaturation techniques and to digestion with proteases. The viral RNA was analyzed in sucrose gradients and by acrylamide-gel electrophoresis and the results obtained show that FMDV-RNA is a single-stranded molecule, having a molecular weight of 2.70 ± 0.05 × 10 6. The origin and causes of the FMDV-RNA heterogeneity are discussed.