Biophysical Studies of Infectious Ribonucleic Acid from Tobacco Mosaic Virus

Following the brilliant discovery by Fraenkel-Conrat [1] and by Gierer and Schramm [2,3] of the infectivity of the ribonucleic acid (RNA) of tobacco mosaic virus (TMV), considerable attention has been devoted to this material. However, a number of important questions persist. It is known that this material is unstable both with respect to its physical properties [4] and to its infectivity. The origin of this instability is as yet obscure. The nature of the products of the instability has not been carefully investigated. Conflicting reports [5-8] have been issued with respect to the possibility that fragments smaller than the intact RNA of the virus can retain biological activity. The low specific infectivity of the viral RNA continues to leave open the question as to whether the infectivity may reside in a minor, special component of the preparation or whether the bulk of the preparation is, at least potentially, infective [9]