Single-stranded, adenine-rich RNA from purified reoviruses.

Abstract

One fourth of the nucleic acid extracted from purified preparations of all 3 reovirus serotypes is single-stranded RNA with more than 90% of its bases as adenine. Like the double stranded (DS) viral RNA genome, the single-stranded component is protected against digestion by micrococcal nuclease, suggesting that it is also enclosed within the virus coat. Whether the adenine (A)-rich RNA is enclosed fortuitously is unknown. Its synthesis is apparently virus-mediated since it is not found in uninfected cells and can be isolated from reovirus growth in either mouse or human cells. On the basis that reovirus contains 10-12 x 106 molecular weight equivalents of RNA, it can be calculated that each particle would contain several hundred molecules of single-stranded RNA if it is assumed that the extracted and virus-associated A-rich RNA are of similar size. This quantity of RNA is in excess of that which would be necessary to link the proposed 9-11 segments of DS RNA. The single-stranded RNA does not have transfer RNA activity and preliminary results indicate that it serves poorly, if at all, as an in vitro messenger in the Escherichia coli system for amino acid incorporation. The role of the A-rich RNA in the replicative cycle of reoviruses remains to be determined.