title: Comparison of the vaccine efficacy of gamma-irradiated Schistosoma japonicum cercariae with the defined antigen Sj62(IrV-5) in pigs.
abstract: Development of a vaccine against Schistosoma japonicum which can protect both man and the domestic animal zoonotic reservoirs of infection would be an invaluable tool in attempts to control this infection in those areas in which conventional control methods have failed to break transmission. The pig is a natural host of S. japonicum and because of its anatomical and immunological similarities to humans, it is a potentially valuable host for studies on S. japonicum in particular and schistosomes in general. Radiation-attenuated cercariae are highly effective in inducing immunity in experimental schistosomosis and there are promising reports of partial protection against schistosomes with recombinant-derived individual antigens. In the present study we have set out to establish a protocol for inducing protection with gamma-irradiated cercariae in pigs and to assess the protective capacity of recombinant and naked DNA formulations of Sj62, a 62kDa region of S. japonicum myosin. The corresponding S. mansoni version or Sj62, recombinant IrV-5, has previously been implicated in irradiated vaccine immunity in S. mansoni infections and has been shown to induce high levels of immunity in a variety of hosts. Groups of pigs were immunised three times at 2-week intervals with 2000 cercariae irradiated at 20krad, with Sj62 as a recombinant (rSj62) incorporated in Freund's adjuvant, a micellar preparation, or as a naked DNA construct. Vaccination with irradiated cercariae did not induce significant anti-Sj62 antibody but following intramuscular challenge with 2000 cercariae, the vaccinated pigs showed >95% resistance as assessed by reduced faecal egg output, worm tissue egg burdens and also reduced septal fibrosis. Immunisation with each of the Sj62 formulations induced significant anti-Sj62 antibody responses, the highest titre (>12,800) being with the Freund's preparation but none of the Sj62-immunised groups showed significant resistance to challenge. The data suggest that Sj62 shows little promise as a vaccine candidate for schistosomosis.
authors.affiliation: Immunology Unit, Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK. quentin.bickle@lshtm.ac.uk
authors.forename: Q D
authors.initials: QD
authors.lastname: Bickle
authors.forename: H O
authors.initials: HO
authors.lastname: Bøgh
authors.forename: M V
authors.initials: MV
authors.lastname: Johansen
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000276:immunology; D000947:Antigens, Helminth / Q000276:immunology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005243:Feces / Q000469:parasitology; D005260:Female; D005720:Gamma Rays; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology*; D008099:Liver / Q000469:parasitology; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D012549:Schistosoma japonicum / Q000276:immunology* / Q000528:radiation effects*; D012554:Schistosomiasis japonica / Q000517:prevention & control / Q000662:veterinary*; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013553:Swine Diseases / Q000517:prevention & control*; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods / Q000662:veterinary*; D014613:Vaccines, Attenuated; D019444:Vaccines, DNA
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D015801:Helminth Proteins; C118909:Sj62 protein, Schistosoma japonicum; D014613:Vaccines, Attenuated; D019444:Vaccines, DNA