Listeria monocytogenes is an important food-borne pathogen that has the capacity to cause severe infections, such as gastroenteritis, septicemia, abortion and meningitis in humans and animals. The alternative sigma factors ( B, C, H, & L) are responsible for regulating transcription of several Listeria monocytogenes virulence factors and stress response genes, including hemolysin gene (hly) that contribute to establishment of intracellular infection.