Protective immunity induced by recombinant Schistosoma hypoxanthine-guanine phosphoribosyltransferase with different adjuvants in mice

Objective:To investigate the protective immunity of recombinant hypoxanthine-guanine phosphoribosyltransferase of Schistosoma japonicum(reSjc HGPRT)plus Montanide ISA 206 or Freund's adjuvants in mice.Methods:Female C57BL/6 mice were randomly divided into five groups,reSjc HGPRT plus Montanide ISA 206 adjuvant,reSjc HGPRT plus Freund's adjuvant,two adjuvant control groups and challenged control group.In Montanide ISA 206 adjuvant or two groups of reSjc HGPRT plus Freund's adjuvant,each mouse was immunized subcutaneously with 20 μg reSjc HGPRT emulsified in Montanide ISA 206 or FCA/FIA,respectively,while in two adjuvant control group,each mouse was injected subcutaneously with sterile normal saline emulsified in FCA/FIA or Montanide ISA 206 respectively.For challenged control group,mice were not treated with recombinant antigen or adjuvant.All mice were vaccinated for three times in an interval of 2 weeks.Two weeks after final immunization,each mouse was challenged with(30±1) cercariae of S.japonicum.At the sixth week after challenged,all mice were sacrificed and the number of worms,pairs of worm and eggs in the livers were counted.The sera collected respectively from mice before immunized,challenged and killed were identified by ELISA assay to detect specific anti-SjcHGPRT IgG antibody.Results:The levels of specific IgG antibody in two immunized groups with reSjc HGPRT was higher than that of challenged control group.Also,compared with the challenged control,the worm reduction rates,worm in pairs rates and egg reduction rates in mice immunized with reSjc HGPRT plus Montanide ISA 206 adjuvant and plus Freund's adjuvant were 53.7%,59.3%,44.9% and 43.3%,44.1%,33.0%,respectively(P0.05).Conclusion:A better immune protection could be obtained in mice immunized with recombinant antigen plus plus Montanide ISA 206 or Freund's adjuvants against S.japonicum.