DNAH8 and infection: Rare systems newly discovered in the species (S. aureus), listed with number of strains matching and taxon of original gene, included abiR, encoding an abortive infection system that inhibits phage DNA replication (27) (13 strains); ietS, encoding the serine protease toxin of the IetAS toxin-antitoxin system (28), (94 strains), and ptuA, encoding the ATPase component of the Septu phage defense system (29) (504 strains).