Host Recognition by

Pathogenic fungi cause a spectrum of infections from annoying to life-threatening with portals of entry that include skin contact, inhalation, and translocation across physical barriers as a result of host defects or accidental or iatrogenic abridgement of epithelial integrity. Some of these agents are also components of normal human flora or may be present in the absence of clinical symptoms. The initial obligate but not sufficient requirement for the establishment of colonization or disease is adherence of the fungus to the host. The mechanisms by which a fungus attaches and maintains contact with the host surface include nonspecific mechanisms such ionic and hydrophobic interactions as well as specific recognition between a ligand and receptor. The focus of this discussion is specific host recognition by pathogenic fungi. Viewing this interaction from the fungal perspective, the fungal component mediating the binding is considered an adhesin. Adhesins, their Iigand(s), and in some cases both partners of the interaction have been identified for several fungi and are discussed in the following sections. Studies with some fungi that describe only a few general characteristics of adherence are not included.