Cell adhesion and invasion mechanisms in microbial pathogenesis

Abstract

Successful colonization of a host by bacterial or protozoan pathogens is a complex event, usually involving a pathogen-encoded &and and a eukaryotic receptor (Beachey, J Infect Db 1981,143:315-345). A microbe has a choice of three types of host components with which it can interact: secreted cell products, host cell surfaces, or extracellular matrices. Microbial pathogens have developed numerous ways to interact with these components [ 11. By coating themselves in secreted host products, pathogens can avoid the host immune system. They can also use them as a bridge to adhere to cell receptors that bind the secreted products. Binding to extracellular matrices tiords a stable environment for pathogen proliferation. Adherence to spectic cell surface molecules confers upon the pathogen the ability to select preferentially which host component it interacts with. Finally, it is becoming apparent that by interacting with cell receptors that are normally involved in cell-cell contact or cell-matrix contact (especially integrins), pathogens are able to hijack these receptors, enter the cell and exist as intracellular parasites. There are many mechanisms used by parasites to interact with host cells, but this review will concentrate on some examples that involve pathogen interactions with extracellular matrix components or host surface receptors involved in cell-matrix or cell-cell contacts. These interactions have shed new light on host-parasite interactions, and are also providing new techniques to study the mechanisms used for cell-cell and cell-matrix contact.