Vaccine strategies against schistosomiasis: From concepts to clinical trials

Schistosomiasis, the second major parasitic disease in the world after mala ria, affects 200 million people. Vaccine strategies represent an essential component of the control of this chronic debilitating disease where the dep osition of millions of eggs in the tissues is the main cause of pathology. Research developed in our laboratory over the last 20 years has led to the identification of novel effector mechanisms, pointing for the first time to the protective role of Th2 responses and of IgE antibodies now supported b y seven studies in human populations. The identification and molecular clon ing of a target antigen, a glutathione S-transferase ( G ST), h as made it possible to demonstrate its vaccine potential in several animal species (ro dents, cattle, primates) and to establish consistently the capacity of vacc ination to reduce female worm fecundity and egg viability through the produ ction of neutralizing antibodies (IgA and IgG). Following promising preclin ical studies, clinical trials (phase I and II) have been undertaken using S chistosoma haematobium GSI, Sh28GST. High titers of neutralizing antibodies were produced (IgG3 and IgA) together with Th2 cytokines, consistently wit h the concepts developed from experimental models. With these results we ar e on the way towards a feasible approach of vaccine development against a m ajor human parasitic disease. Copyright (C) 2001 S. Karger AG, Basel.