Antigen Epitope Peptides and Immunogenicity Analysis of E. coli O157: H7 Ivy Protein

To evaluate the feasibility of synthetic polypeptides O157:H7 Ivy146-157 as a vaccine antigen, a bioinformatics method was employed to analyze the secondary structures, hydrophilicity plot, flexibility plot, surface probability plot and antigenic index of the Ivy. A B-cell epitope peptide sequence was identified and synthesized. BALB/c mice were immunized with Ivy146-157, antibody titers and splenic lymphocytes proliferations in mice were tested. The results showed that the antibody titers were 1:6 400 after immunized mice three times. And the native Ivy protein of O157:H7 R14 strain was identified by polyclone antibody Ivy146-157. The MTT assay results indicated the splenic lyphocytes were increased after immunized polypeptides Ivy146-157, and had significant difference with the control group (P<0.05). These results indicated that polypeptides Ivy146-157 could induce a strong humoral and celluar immune respond, and it would provide a theory as a vaccine antigen for further researches.