Septicolysin is a member of thiol-activated cytolysins which have been implicated in the pathogenesis of infections by several Gram-positive pathogens such as Clostridium perfringens, Listeria monocytogenes, and Streptococcus pneumoniae and are characterized by their cytolytic activity for eukaryotic cells (Billington et al., 2000). This evidence concerns the gene PRF1 and infection.