Chlamydia Adhesion and Invasion
Matthew D. Romero, Katja Mölleken, Johannes H. Hegemann and Rey A. Carabeo
from: Chlamydia Biology: From Genome to Disease (Edited by: Ming Tan, Johannes H. Hegemann and Christine Sütterlin). Caister Academic Press, U.K. (2020) Pages: 59-84.
Chlamydiae are obligate intracellular pathogens that require a specialized intracellular niche for their survival and replication. Hence, they possess an efficient means of gaining access to this niche. Adhesion and invasion of Chlamydia to host cells are the initiating processes of infection and pathogenesis, and thus it is important to characterize this process in detail. In vivo, the primary targets are the epithelial cells that line the mucosa of the ano-genital tract, conjunctiva, the respiratory tract, and the gut. These cells are non-phagocytic. In order for Chlamydia to invade these cells, they must induce their uptake by actively remodeling the cortical actin cytoskeleton and manipulating the endocytic machinery to facilitate the phagocytosis of infectious elementary bodies (EBs). Uptake is preceded by the stable adherence of EBs to the surface of epithelial cells. Stable adhesion is followed by the induction of signalling pathways that trigger a number of host cell processes, including remodeling of the cortical actin to facilitate uptake of the pathogen. Adhesion and the induction of signalling to the cytoskeletal remodeling machinery are shared by a number of chlamydial species, with C. trachomatis and C. pneumoniae being the best studied. Chlamydial adhesins stabilize the bacterium at the surface of the host cell via interaction with host cell surface receptors. This adhesion step does not need to be highly specific. It involves transient electrostatic interactions followed by more specific associations between chlamydial adhesins and specific receptors to trigger signalling within the host cell and initiate actin remodeling at the cell surface. Localized actin remodelling results in the formation of a variety of cell surface structures designed to internalize the invading bacteria. In this chapter, we will review the mechanisms of chlamydial adhesion and invasion, with a focus on bacterial and host factors that control these steps and that have been identified within the last decade read more ...