Studies on phage displayed mimotopes of a protective monoclonal antibody (SSj14) against Schistosoma japonicum / 生物工程学报

ABSTRACT

To obtain peptides mimicking epitope of a protective McAb SSjl4 specific to Schistosoma japonicum and investigate their immuno-protection effects. A phage random 12 peptide library was screened using purified McAb SSj14, 33 clones were picked up for specificity identification by ELISA. The epitope of each positive clones were detected by the sequencing analysis technique. The antigenicity of three positive clones (P1, P2 and P11) and their mixture cock-tail were further confirmed by Western-blotting, and their protective efficiency were evaluated by mice vaccination experiment. IL-12 level between the vaccinated mice and control mice were compared. 30 positive phage clones were obtained, which represented 11 different epitopes respectively, there were a similar sequence "H-N/Q-X-S-P/F-X-X-L-A-T" among all of the epitopes. Western-blotting showed that all of the three tested clones were recognized by McAb SSj14. Significant adult worm reduction (13.84% to approximately 52.83%), liver tissue egg reduction (34.17% to approximately 65.47%) as well as fecal egg reduction (28.89% to approximately 73.78%) were observed in mice vaccinated with phages of P1, P2, P11 and mixture of three clones when compared with those of the blank control group, among them, the mice vaccinated with the mixture of phage clones got higher protection than any of the mice injected with only one kind of clone phages. At the same time, the IL-12 level in serum of vaccinated mice was found higher than those of the blank control one, this suggest that IL-12 may correlate with the protective efficiency induced by the clone phages. The study provides a new way for developing an effective vaccine against S. japonicum.