Vaccine strategies against schistosomiasis

Abstract

Schistosomiasis, the second major parasitic disease in the world after malaria affects at least 200 million people, 500 million being exposed to the risk of infection. It is widely agreed that a vaccine strategy which could lead to the induction of effector mechanisms reducing the level of reinfection and ideally parasite fecundity would deeply affect the incidence of pathological manifestations as well as the parasite transmission potentialities. Extensive studies performed in the rat model have allowed the identification of novel effector mechanisms involving IgE antibodies and various inflammatory cell populations (eosinophils, macrophages and platelets) whereas regulation of immune response by blocking antibodies has been evidenced. Recent epidemiological studies have now entirely confirmed in human populations the role of IgE antibodies in the acquisition of resistance and the association of IgG4 blocking antibodies with increased susceptibility. On the basis of these concepts, several schistosome target proteins have been identified and their encoding genes cloned. One of them, a schistosome glutathione S-transferase (Sm 28 GST) appears as a promising vaccine candidate. Immunization experiments have shown that two complementary goals can be achieved: (a) a partial but significant reduction of the worm population (up to 60% in rats); (b) a significant reduction of parasite fecundity (up to 70% in mice and 85% in cattle) and egg viability (up to 80%). At least two distinct immunological mechanisms account for these two effects. IgE antibodies appear as a major humoral component of acquired resistance whereas IgA antibodies appear as a major humoral factor affecting parasite fecundity.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and Characterization of Sarcoptes Scabiei and Dermatophagoides Pteronyssinus Glutathione S-Transferases: Implication as a Potential Major Allergen in Crusted Scabies

“…In S. mansoni infection, high levels of IgE were associated with resistance, whereas high levels of IgG4 antibodies were associated with increased susceptibility. 44 IgG4 is thought to compete with IgE for the same parasite epitopes in both schistosomiasis and filariasis. 45 The pattern of IgG4 reactivity observed here, like that of IgE, was much greater in the crusted scabies patients.…”

Fasciola hepaticaFatty Acid Binding Protein Inhibits TLR4 Activation and Suppresses the Inflammatory Cytokines Induced by Lipopolysaccharide In Vitro and In Vivo

“…Endotoxins were removed from the Fh12 by using polymyxin B (PMB)-columns (31) according to the manufacturer’s instructions. The presence of endotoxins was assessed prior to and after removing endotoxins using the Chromogenic Limulus Amebocyte Lysate (LAL) QCL-1000 Assay (Lonza, Walkersville, MD, USA) following the manufacturer’s instructions.…”

“…Cells were incubated in the extraction buffer on ice using a rocking platform for 30 min before being centrifuged at 20,000 × g for 10 min at 4°C. Supernatants were transferred to clean tubes, and protein concentrations were determined using a BCA protein assay kit (31). …”

Identification and localization of glutathione S-transferase as a potential target enzyme in Brugia species

“…These biological functions make GSTs molecular targets for new anti®larial drugs (Brophy and Pritchard 1994). GST isozymes have shown potential as protective antigens against fascioliasis and schistosomiasis (Balloul et al 1987;Mitchell 1989;Sexton et al 1990;Boulanger et al 1991;Capron et al 1992;Xu et al 1993).…”