To confirm the immunogenicity of these peptides in vivo, we analyzed sera derived from peptide-immunized mice. The five positive peptides and two control peptides (P6 and P30) were coupled with keyhole limpet hemocyanin (KLH) and were used to immunize BALB/c mice ( Table 1 ). The antisera were collected five days after the third immunization and titrated by ELISA using corresponding peptide as a coating antigen. Our results showed that all of the peptide conjugates except P15 induced potent antibody titers. The endpoint titers of antisera in ELISA from mice immunized with P3, P5, P6, P16, P30, and P31 peptides were 1:6,400, 1:51,200, 1:51,200, 1:12,800, 1:51,200, and 1:25,600, respectively ( Fig. 2A) . These data indicate that most of the positive peptides elicite humoral immunity and are highly immunogenic in mice.