Schistosoma japonicum: The design and experimental evaluation of a multivalent DNA vaccine

Abstract

The aim of this study was to construct and evaluate the immunity efficacy of the DNA multivalent vaccine pVIVO2SjFABP-23. The vaccine was constructed and produced as follows. Forty BALB/c mice were divided into four groups designated pVIVO2, pVIVO2Sj23, pVIVO 2SjFABP and pVIVO2SjFABP-23. Each mouse was immunized with 100 μ g of the corresponding plasmid DNA by intramuscular injection. 28 days post-vaccination, the mice were challenged with S. japonicum cercariae, and the worm and egg burdens were determined 42 days post-challenge. Serum samples were collected from all the mice before and after vaccination and at the end of the experiment, and used for antibody detection. The IFN-γ and IL-4 levels were quantified in the supernatants of specifically stimulated spleen cells. The number of worms was reduced by 52%, 40% and 42% in mice respectively immunized with pVIVO2SjFABP-23, pVIVO2Sj23 or pVIVO 2SjFABP. A respective 61%, 38% and 39% egg reduction was determined relative to those mice that only received the empty pVIVO2 plasmid. pVIVO2SjFABP-23 immunization increased IgG levels against SWAP and SEA. Increased IFN-γ levels were detected in the supernatant of specific stimulated spleen cells from mice immunized with the 3 different constructs. The multivalent DNA vaccine developed induced higher levels of protection than the two monovalent tested vaccines. © 2006 by the University of Wrocław.