title: Multiple vaccinations with UV- attenuated cercariae in pig enhance protective immunity against Schistosoma japonicum infection as compared to single vaccination.
abstract: BACKGROUND
  Schistosomiasis japonica is a major public health problem in the endemic areas of China, the Philippines, and Indonesia. To date, a vaccine has not been developed against this disease but immunization with UV-attenuated cercariae can induce a high level of protective immunity in Landrace/Yorkshire/Duroc crossbred pigs. To compare the efficacy of a single vaccination and multiple vaccinations with UV-attenuated Schistosoma japonicum cercariae, two groups of pigs received either one or three exposures to 10,000 cercariae attenuated with 400 μw UV.
  
  
  RESULTS
  Pigs with a single immunization had a 59.33% reduction in adult worm burden, a 89.87% reduction in hepatic eggs and a 86.27% reduction in fecal eggs at eight weeks post-challenge (P < 0.01). After three immunizations, protection increased to 77.62%, 88.8% and 99.78% reduction in adult worms, hepatic eggs and fecal eggs, respectively (P < 0.01). Humoral and cellular immunological parameters measured indicated that schistosome-specific IgG1 and IgG2 levels in the vaccinated groups were higher than in the infection-control group. Triple vaccinations resulted in higher levels of antibodies, especially IgG2, compared with a single vaccination and IFN-γ levels increased with repeated immunization with UV-irradiated cercariae.
  
  
  CONCLUSIONS
  The high levels of protection against S. japonicum infection can be achieved with a UV-attenuated vaccine in pigs, and that three vaccinations were possibly more effective than a single vaccination. Moreover, triple vaccinations evoked a more vigorous IFN-γ response and a stronger antibody-mediated response, especially an increase in the levels of IgG2 antibodies.
authors.affiliation: Department of Pathogen Biology & Immunology, Nanjing Medical University, Nanjing, Jiangsu, China. jiminjun@njmu.edu.cn
authors.forename: Dandan
authors.initials: D
authors.lastname: Lin
authors.forename: Fang
authors.initials: F
authors.lastname: Tian
authors.forename: Haiwei
authors.initials: H
authors.lastname: Wu
authors.forename: Yanan
authors.initials: Y
authors.lastname: Gao
authors.forename: Jingjiao
authors.initials: J
authors.lastname: Wu
authors.forename: Donghui
authors.initials: D
authors.lastname: Zhang
authors.forename: Minjun
authors.initials: M
authors.lastname: Ji
authors.forename: Donald P
authors.initials: DP
authors.lastname: McManus
authors.forename: Patrick
authors.initials: P
authors.lastname: Driguez
authors.forename: Guanling
authors.initials: G
authors.lastname: Wu
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D058487:Cercaria / Q000276:immunology*; D004195:Disease Models, Animal; D005243:Feces / Q000469:parasitology; D007117:Immunization, Secondary / Q000379:methods; D007074:Immunoglobulin G / Q000097:blood; D008099:Liver / Q000469:parasitology; D010270:Parasite Egg Count; D012549:Schistosoma japonicum / Q000276:immunology*; D012554:Schistosomiasis japonica / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control; D014466:Ultraviolet Rays; D014611:Vaccination / Q000379:methods*; D014612:Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000909:Antibodies, Helminth; D007074:Immunoglobulin G; D014612:Vaccines; D014613:Vaccines, Attenuated