Antigens of gastrointestinal nematodes.

Nematodes occupying the gastrointestinal (GI) tract of man shed an as yet undefined array of chemicals into their environment. To combat effectively the potentially debilitating disease caused by infection with these organisms we must (a) define the parasite products chemically, (b) determine their ability to induce protective immunity (or to counter a protective immune response), and (c) establish their potential for the diagnosis of infection. Whilst it has become clear that "antigens" can be derived from within the parasite and from the turnover of external cuticular components (the term "ES" must include both), further work is necessary to establish the significance of these molecules to the survival of the parasite. In this context, a number of questions will be answered in the near future. For example, how important is the hookworm protease to parasite nutrition? Can vaccination using the genetically engineered and purified enzyme generate protective immunity? Will the stichocyte secretions of Trichuris trichiura prove to be as immunogenic as those of Trichinella spiralis? (Surprisingly, little has been published with regard to the presence of enzymes in stichocyte secretions.) Are GI nematodes on the way out?