Abstract: Listeria monocytogenes (LM) is a zoonotic food-borne pathogen with strong virulence. It has a high lethality due to the host barrier penetrability and intracellular parasitism. Hence, consumption of foods contaminated with LM causes food safety problems. In this study, LM strains with the deletion of the gene encoding the important virulence factors such as internalin A (InlA) and internalin B (InlB) and human colon Caco-2 and liver HepG2 cells were used to investigate the effect of inlA and inlB gene deletion on the ability of LM to invade host cells and induce cell apoptosis. The results showed that inlA and inlB deletion significantly reduced the ability of LM to invade host cells and induce cell apoptosis (P < 0.05) and resulted in a decrease of over 50% in invasion rate and a decrease of 30%–50% in the proportion of apoptotic cells compared with the wild-type strain. Therefore, inlA and inlB were confirmed to play an important role in host invasion and cell apoptosis induction by LM, which is helpful to intensively study the nosogenesis of LM and the molecular mechanisms by which LM causes host immunoreaction and induces cell apoptosis.

Key words: Listeria monocytogenes, virulence factors, internalins, host cell invasion, cell apoptosis