ACTA1 and listeriosis: Unlike L. innocua, the ability of L. monocytogenes to cause listeriosis is known to be multifaceted and has been attributed to six virulence genes, prfA, plcA, hly, mpl, actA, and plcB, which are located in the PrfA-dependent virulent gene cluster known as LIPI-1 [77,78], other Listeria pathogenicity islands, namely LIPI-3 and LIPI-4, Internalins (inl) genes, and other virulence genes, as reported by Glimour et al. [79].