Viral Hepatitis
Copyright ©2006 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Nov 28, 2006; 12(44): 7126-7135
Published online Nov 28, 2006. doi: 10.3748/wjg.v12.i44.7126
Elicitation of strong immune responses by a DNA vaccine expressing a secreted form of hepatitis C virus envelope protein E2 in murine and porcine animal models
Yi-Ping Li, Hye Na Kang, Lorne A Babiuk, Qiang Liu
Yi-Ping Li, Hye Na Kang, Lorne A Babiuk, Qiang Liu, Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Yi-Ping Li, Danish Institute for Food and Veterinary Research, Arhus N, Denmark
Hye Na Kang, Korea Food and Drug Administration, Seoul, Republic of Korea
Supported by the Canadian Network for Vaccines and Immuno-therapeutics
Correspondence to: Dr. Qiang Liu, Vaccine and Infectious Disease Organization, University of Saskatchewan, 120 Veterinary Road, Saskatoon, Saskatchewan, S7N 5E3, Canada. qiang.liu@usask.ca
Telephone: +1-306-9661567 Fax: +1-306-9667478
Received: July 23, 2006
Revised: July 28, 2006
Accepted: September 1, 2006
Published online: November 28, 2006
Abstract

AIM: To characterize the immunogenicity of a hepatitis C virus (HCV) E2 DNA vaccine alone or with a protein vaccine boost in murine and porcine animal models.

METHODS: A DNA vaccine expressing a secreted form of HCV E2 protein was constructed and used to vaccinate mice and piglets with or without boosting with a recombinant E2 protein vaccine formulated with CpG ODN and 10% Emulsigen. The immunogenicity of HCV E2 vaccines was analyzed by ELISA for antibody responses, MTT assay for lymphocyte proliferation, ELISPOT for the number of interferon-γ secreting cells, and cytotoxic T lymphocyte assays.

RESULTS: Intradermal injection of E2 DNA vaccine induced strong Th1-like immune responses in mice. In piglets, E2 DNA vaccine elicited moderate and more balanced immune responses. A DNA vaccine prime and protein boost vaccination strategy induced significantly higher E2-specific antibody levels and shifted the immune response towards Th2-like ones in piglets.

CONCLUSION: A DNA vaccine expressing a secreted form of HCV E2 protein elicited E2-specific immune responses in mice and piglets. Recombinant E2 protein vaccination following DNA immunization significantly increased the antibody response in piglets. These HCV E2 vaccines may represent promising hepatitis C vaccine candidates for further investigations.

Keywords: Hepatitis C virus E2; DNA vaccine; DNA vaccine prime-protein boost