Original Articles
Copyright ©The Author(s) 2000. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 15, 2000; 6(2): 239-243
Published online Apr 15, 2000. doi: 10.3748/wjg.v6.i2.239
DNA-based vaccination induces humoral and cellular immune responses against hepatitis B virus surface antigen in mice without activation of C-myc
Lian San Zhao, Shan Qin, Tao You Zhou, Hong Tang, Li Liu, Bing Jun Lei
Lian San Zhao, Shan Qin, Tao You Zhou, Hong Tang, Li Liu, Bing Jun Lei, The First Hospital, West China University of Medical Sciences, Chengdu 610041, China;
Lian San Zhao, Shan Qin, Hong Tang, Li Liu, Bing Jun Lei Key Laboratory of Sichuan Province for Molecular Biology of Infectious Diseases, Chengdu 610041, China;
Lian San Zhao, graduated from West China University of Medical Sciences in 1968, now professor of infectious diseases, specialized in viral hepatitis, having 60 papers published.
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, No.39670670
Correspondence to: Dr. Lian San Zhao, Department of Infectious Diseases, the First Hospital, West China University of Medical Sciences, Chengdu 610041, China. zlsmalab@public.sc.cninfo.net
Telephone: +86-28-5422650, Fax. +86-28-5582944
Received: July 1, 1999
Revised: January 6, 2000
Accepted: February 1, 2000
Published online: April 15, 2000
Abstract

AIM: To develop a safe and effective DNA vaccine for inducing humoral and cellular immunological responses against hepatitis B virus surface antigen (HBsAg).

METHODS: BALB/c mice were inoculated with NV-HB/s, a recombinant plasmid that had been inserted S gene of hepatitis B virus genome and could express HBsAg in eukaryotes. HBsAg expression was measured by ABC immunohistochemical assay, generation of anti-HBs by ELISA and cytotoxic T lymphocyte (CTL), by MTT method, existence of vaccine DNA by Southern blot hybridization and activation of oncogene C-myc by in situ hybridization.

RESULTS: With NV-HB/s vaccination by intramuscular injection, anti-HBs was initially positive 2 wk after inoculation while all mice tested were HBsAg positive in the muscles. The titers and seroconversion rate of anti-HBs were steadily increasing as time went on and were dose-dependent. All the mice inoculated with 100 μg NV-HB/s were anti-Bs positive one month after inoculation, the titer was 1∶1024 or more. The humoral immune response was similar induced by either intramuscular or intradermal injection. CTL activities were much stronger (45.26%) in NV-HB/s DNA immunized mice as compared with those (only 6%) in plasma-derived HBsAg vaccine immunized mice. Two months after inoculation, all muscle samples were positive by Southern-blot hybridization for NV-HB/s DNA detection, but decreased to 25% and all were undetectable by in situ hybridization after 6 mo. No oncogene C-myc activation was found in the muscle of inoculation site.

CONCLUSION: NV-HB/s could generate humoral and cellular immunological responses against HBsAg that had been safely expressed in situ by NV-HB/s vaccination.

Keywords: hepatitis B virus; DNA vaccine; HBsAg; cellular immunity; oncogene C-myc