Segmented Structure of the Reovirus Genome

The genome of reovirus consists of double-stranded RNA with a mol wt of approximately 16 × 106 daltons. When the double-stranded RNA is extracted from purified virions or infected cells it is obtained in fragments that fall into three size classes with average mol wt of 0.9 × 106, 1.6 × 106 and 2.7 × 106 (Millward and Graham, 1970, and references quoted therein). Corresponding to the three classes of double-stranded RNA there are three size classes of single-stranded RNA synthesized in cells infected with reovirus (Bellamy and Joklik, 1967a; Watanabe and Graham, 1967). These are messenger RNAs (mRNAs) copied from the viral genome (Prevec and Graham, 1966; Shatkin and Rada, 1967). Each class of mRNA hybridizes exclusively and throughout its length with that class of viral double-stranded RNA of similar size (Bellamy and Joklik, 1967a; Watanabe et al., 1967). Whatever the actual physical structure of the viral genome might...