Regulation of exoprotein gene expression by the Staphylococcus aureus cvfB gene.

We previously reported that the cvfB gene (SA1223) of Staphylococcus aureus is responsible for the virulence of this pathogenic bacterium. We show here that the cvfB gene regulates exoprotein gene expression. In a cvfB gene deletion mutant, hemolysin, DNase, and protease production were decreased, whereas protein A expression was increased. The amount of RNAIII, the transcript from the P3 promoter in the agr locus that regulates the expression of various virulence factors, was also reduced in the cvfB mutant. In addition, P2 and P3 promoter activity in the agr locus was decreased in the mutant. Under the genetic background of the agr-null mutation, cvfB gene disruption decreased the production levels of DNase and protease. Moreover, the cvfB and agr double mutant was less virulent than the agr mutant in silkworms. These results suggest that the cvfB gene product contributes to the expression of virulence factors and to pathogenicity via both agr-dependent and agr-independent pathways.