Abstract: Objective To investigate the protective immunity against Schistosoma japonicum in mice immunized with recombinant specific very low density lipoprotein binding protein (SVLBP) and its potential as vaccine candidate. Methods Recombinant SVLBP antigen was over-expressed under IPTG induction and purified by Ni-NTA affinity chromatography. C57BL/6 mice were immunized three times with purified reSVLBP complexed with Freund's adjuvant, at biweekly intervals. Then 35±1 cercariae of S. japonicum were given to each mouse by abdominal skin 10 days after the 3rd immunization. 45 days later, all mice were sacrificed to collect adult worms and count liver eggs. serum samples were collected before immunization and after challenge respectively, and were probed the antigen-specific antibodies using a panel of ELISAs. Results The worm burden and the egg deposition in liver tissue were reduced by 33.4% and 47.6% respectively in the immunized group, in comparison with the adjuvant control group (P<0.05). Higher titer (>1:6 400) of total IgG was observed after challenge infection. The vaccinated mice developed significantly higher levels of IgG2a, IgG2b,IgG1 than those of control mice. Conclusion The recombinant tegumental SVLBP antigen could induce partial protection against S. japonicum infection. These data demonstrate the potential of SVLBP as a schistosome vaccine candidate.

Key words: Schistosoma japonicum, Tegumental protein, SVLBP, Immunoprotection