TDH and infection: VPA0288 was previously shown to be expressed and secreted from V. parahaemolyticus, albeit at very low levels (27), and yet, past studies have shown that the only virulence factors that mediate HeLa cell lysis during infections of cell cultures are the thermostable direct hemolysin (TDH)/TDH-related hemolysin (TRH) and the T3SSs encoded by this pathogen (46, –, 48).