C3 and infection: We found that eLtaS had no effect on the deposition of C3b, but the interaction between eLtaS and C3b resulted in attenuated engulfment of C3b-deposited S. aureus by phagocytes, demonstrating that eLtaS aggravates infection by mediating evasion of phagocytosis by C3b-deposited S. aureus.