To further explore the roles of sly in invasive infection of the 05ZYH33 strain, the sly gene was in-frame substituted by the Cm gene in the S. suis 05ZYH33 strain, to generate the nonpolar mutant Δsly. The mutant Δsly strain showed reduced hemolytic activity, but similar growth rates compared to the wild-type strain S. suis 05ZYH33 (Fig. 3). This evidence concerns the gene SASH3 and infection.