Abstract
In order to develop an experimental DNA vaccine for the prevention and treatment
of hepatitis B virus infection, hepatitis B virus surface antigen (HBsAg) DNA
was subcloned into an E. coli-eukaryotic cell shuttle vector and was expressed
in the Baculovirus expression system. Intramuscular, intradermal, and
intraperitoneal injections of 30 microg of the plasmid DNA expressing HBsAg
induced humoral and cellular immune responses in ICR mice. The first IgG
antibodies were detected after ten days and specific IgG antibody titers peaked
after two months of a single intramuscular DNA injection. Anti-HBs antibody
titers gradually increased and peaked at four months following intradermal DNA
injection, and in case of intraperitoneal injection they peaked at seven months.
Generation of HBs-specific helper T lymphocytes was also investigated through
the production of interleukin-2 by T helper cells. Boosting effects of HBs DNA
were investigated without much results. In general, DNA-mediated HBs
immunization induced humoral and cellular immune responses in mice that appears
to simulate immune responses in human during the course of HBV vaccination.