Host control of yeast dsRNA virus propagation and expression.

Yeast controls propagation of the L-A dsRNA virus, and thus pathogenicity, by partially blocking translation of viral mRNA. L-A makes a Gag-Pol fusion protein by a -1 ribosomal frameshift, regulated by the host but critical for satellite RNA propagation. Discovery of the KEX proteases, by their requirement for killer toxin expression from a satellite dsRNA of L-A, led to the identification of mammalian prohormone processing proteases.