Gene disruption indicates that the only essential function of the SKI8 chromosomal gene is to protect Saccharomyces cerevisiae from viral cytopathology.

We have cloned the SKI8 gene, one of the chromosomal genes that repress replication of M, L-A, and L-BC double-stranded RNA viruslike particles in yeast. The clone was used to map SKI8 to chromosome VII near ade5 and to construct a deletion mutant. The deletion mutant was unable to grow at 8 degrees if and only if M1 double-stranded RNA was present.