Sequences at the 3′ ends of yeast viral dsRNAs: Proposed transcriptase and replicase initiation sites

ScV is a double-stranded RNA virus of yeast consisting of two separately encapsidated dsRNAs (L and M). ScV-1 and ScV-2 are two dsRNA viruses present in two different yeast killer strains, K1 and K2. Our 3′ end sequence analysis shows that the two sets of viral dsRNAs from ScV-1 and ScV-2 are very similar. Consensus sequences for transcriptase and replicase initiation are proposed. A stem and loop structure with a 3′ terminal AUGC sequence, like that of several plant virus plus strand RNAs, is present at the putative replicase initiation site of one of the yeast viral RNA plus strands.