Abstract: AIM: To explore the cross protection against S.japonicum cercaria challenge in mice
immunized with T. spiralis larva antigen. METHODS:Groups of BALB/c mice were immunized with 4
preparations of T.spiralis larva antigen, respectively.Vaccinated mice were then challenged with
30 and 100 S.japonicum cercariae,respectively.Forty five days later,all mice were sacrificed and
examined for adult worm burden,liver and stool egg count. RESULTS: All groups of mice immunized
with 4 preparations of T. spiralis larvae antigen withou tadjuvant showed significant protection against S. japonicum. Among these antigen preparations, the soluble antigen (TsLSA ) presented highest protection with reductions in worm burden and liver and stool egg counts of 21.3% , 48.0% and 58.5% , respectively. When mice were immunized with TsLSA plus Freund’s complete adjuvant (FCA) or with double-dose of the antigen, the worm reduction rate was increased to 29.3% and 39.6% , respectively. CONCLUSION:Different preparations of T. spiralis muscle larva antigen could induce protection against S. japonicum in mice.

Key words: Schistosoma japonicum, Trichnella spiralis, immunization, cross protection