[Studies on the mimic short peptide-based vaccine: immunoprotection in mice against Schistosoma japonicum infection].

Objective: To evaluate the immunoprotective effect of the mimic short peptide-based vaccine of Schistosoma japonicum (S.j) in mice.

Methods: Phage random peptide library of 12 amino acids was immunoscreened with purified IgG from sera of rats. Three rounds of biopanning were carried out. The positive clones were randomly selected, detected and sequenced. Kunming mice were immunized with positive clones three times (0, 2, 4 weeks). Each mouse was infected with 40 cercariae after 2 weeks of the 3rd immunization. After 42 days of infection, the mice were killed. Adult worms and the liver eggs were counted.

Results: The specific phages binding to IgG were enriched after 3 rounds of biopanning. Two short peptides were obtained. Compared with the control groups, the mixture of two mimic peptides induced 34.9% (P < 0.05) worm reduction and 67.6% (P < 0.001) total liver egg reduction in mice. Two different mimic peptides induced 31.0% (P < 0.05), 14.5% (P > 0.05) worm reduction and 61.2% (P < 0.001), 35.7% (P < 0.05) total liver egg reduction respectively. The specific antibody could be induced by the mimic peptides and detected by ELISA in immunized mice, and the antibody titer reached more than 1:6,400.

Conclusion: The 2 different mimic peptides obtained by immunoscreening phage random peptide library show partial immunoprotection against S. j infection.