Molecular and Genetic Determinants Involved in Invasion of Mammalian Cells by Listeria monocytogenes

Abstract

Intracellular pathogens can be artificially divided into two groups, those which are present only in phagocytes and those which also enter and replicate in nonprofessional phagocytic cells. The process of entry into nonphagocytic cells is often referred to as “parasite-directed endocytosis”or “induced phagocytosis”, since it involves the participation of both the pathogen and the host eukaryotic cell. In those cases where it has been carefully studied, interaction between a bacterial ligand and the host cell receptor results in stimulation of host signaling pathways and the subsequent cytoskeletal rearrangements necessary for uptake (BLISKA et al. 1993). Phagocytosis by professional phagocytes is generally different from “induced phagocytosis”in at least two aspects: (a) Internalization is mainly a “hostdirected” event resulting from deposition on the bacterium of antibodies or other compounds recognized by phagocyte receptors, (b) Professional phagocytes can produce potent microbicidal radicals or compounds that intracellular bacteria must circumvent, alter, or destroy in order to survive.