Interactions of respiratory pathogens with host cell surface and extracellular matrix components.

Adhesion of pathogens to proteins and glycoconjugates on the host cell plasma membrane or to components of the extracellular matrix is a critical early step in the initiation of infection. For intracellular pathogens, adhesion to the cell surface is a prerequisite to gaining entry into the cell. In all cases, adhesion to host tissue prevents elimination of the pathogens by normal clearance processes and may help the organism to evade immune surveillance by the host. Many laboratories are investigating the ligand binding specificities of bacterial receptors or adhesions and have described diverse binding specificities for adhesive proteins in the host extracellular matrix including laminin and fibronectin. Many bacteria also have adhesins that bind to carbohydrates occurring on glycolipids and glycoproteins in the apical membranes of epithelia in tissues that are targets for infection. Definition of these binding specificities and identification of the receptors that mediate adhesion may lead to development of a novel class of antibiotics whose mechanism of action is to compete with the endogenous ligands for binding to the pathogen receptors or to otherwise prevent adhesion to host tissues and thereby prevent infection.