Viral Hepatitis
Copyright ©The Author(s) 2004. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 1, 2004; 10(17): 2488-2492
Published online Sep 1, 2004. doi: 10.3748/wjg.v10.i17.2488
A candidate DNA vaccine elicits HCV specific humoral and cellular immune responses
Li-Xin Zhu, Jing Liu, Ye Ye, You-Hua Xie, Yu-Ying Kong, Guang-Di Li, Yuan Wang
Li-Xin Zhu, Jing Liu, Ye Ye, You-Hua Xie, Yu-Ying Kong, Guang-Di Li, Yuan Wang, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
Author contributions: All authors contributed equally to the work.
Supported by the National High Technology R&D Program of China, No. 2001AA215171
Correspondence to: Professor Yuan Wang, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Yue-Yang Road 320, Shanghai 200031, China. wangy@sibs.ac.cn
Telephone: +86-21-54921103 Fax: +86-21-54921011
Received: February 2, 2004
Revised: February 14, 2004
Accepted: February 21, 2004
Published online: September 1, 2004
Abstract

AIM: To investigate the immunogenicity of candidate DNA vaccine against hepatitis C virus (HCV) delivered by two plasmids expressing HCV envelope protein 1 (E1) and envelope protein 2 (E2) antigens respectively and to study the effect of CpG adjuvant on this candidate vaccine.

METHODS: Recombinant plasmids expressing HCV E1 and E2 antigens respectively were used to simultaneously inoculate mice with or without CpG adjuvant. Antisera were then collected and titers of anti-HCV antibodies were analyzed by ELISA. One month after the last injection, animals were sacrificed to prepare single-cell suspension of splenocytes. These cells were subjected to HCV antigen specific proliferation assays and cytokine secretion assays to evaluate the cellular immune responses of the vaccinated animals.

RESULTS: Antibody responses to HCV E1 and E2 antigens were detected in vaccinated animals. Animals receiving CpG adjuvant had slightly lower titers of anti-HCV antibodies in the sera, while the splenocytes from these animals showed higher HCV-antigen specific proliferation. Analysis of cytokine secretion from the splenocytes was consistent with the above results. While no antigen-specific IL-4 secretion was detected for all vaccinated animals, HCV antigen-specific INF-γ secretion was detected for the splenocytes of vaccinated animals. CpG adjuvant enhanced the secretion of INF-γ but did not change the profile of IL-4 secretion.

CONCLUSION: Vaccination of mice with plasmids encoding HCV E1 and E2 antigens induces humoral and cellular immune responses. CpG adjuvant significantly enhances the cellular immune response.

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