Abstract: Provided is a gene for expressing an immunogenic polypeptide on the cell surface of a bifidobacterium, and the gene includes a gene encoding the immunogenic polypeptide, the immunogenic polypeptide includes a predetermined base domain and at least one antigenic peptide, and the at least one antigenic peptide is linked on any of the N-terminal side and the C-terminal side of the base domain. The gene for expressing an immunogenic polypeptide on a cell surface of a bifidobacterium of the present invention can further include a gene encoding a bifidobacterium-derived GNB/LNB substrate-binding membrane protein.

Abstract: Provided is a gene for expressing an immunogenic polypeptide on the cell surface of a bifidobacterium, and the gene includes a gene encoding the immunogenic polypeptide, the immunogenic polypeptide includes a predetermined base domain and at least one antigenic peptide, and the at least one antigenic peptide is linked on any of the N-terminal side and the C-terminal side of the base domain. The gene for expressing an immunogenic polypeptide on a cell surface of a bifidobacterium of the present invention can further include a gene encoding a bifidobacterium-derived GNB/LNB substrate-binding membrane protein.

Abstract: A HCV particle formation promoter is capable of promoting formation of HCV particles in culture cells, and a method enhances production of HCV particles. A method evaluates an anti-HCV agent candidate substance, and a method produces a HCV vaccine. The HCV particle formation promoter includes as an active ingredient a statin or a pharmaceutically acceptable salt thereof. Addition of the statin or pharmaceutically acceptable salt thereof to HCV-infected culture cells can promote formation of infectious HCV particles and enhance production of the particles. In addition, an anti-HCV agent candidate substance is evaluated by culturing HCV-infected cells in the presence of the HCV particle formation promoter and the anti-HCV agent candidate substance. Further, a HCV vaccine is produced by using HCV particles produced by the method of enhancing production of HCV particles.