Construction of eukaryotic expression plasmids inserting HBsAg gene and DNA immunization responses to HBsAg in mice / 中华肝脏病杂志

ABSTRACT

<p><b>OBJECTIVE</b>To study the HBsAg transient expression in HepG2 or COS-7 cells with eukaryotic expression plasmids inserting HBsAg gene (pCI-S and pcDNA3.1-S) and the efficacy of naked DNA immunization in mice.</p><p><b>METHODS</b>Firstly, the recombinant plasmids of pCI-S and pcDNA3.1-S were constructed by the cloning technique and the accuracy of these constructs was confirmed by restriction enzyme digestion and DNA sequencing. Secondly, plasmids of pCI-S and pcDNA3.1-S were transferred into HepG2 and COS-7 cells, respectively by means of cationic liposome. HBsAg transient expression was assayed by ELISA in cell culture supernatants and cell lysates. Thirdly, plasmids were injected into quadriceps muscles of BALB/C mice and serum samples were obtained from individual immunized or control mice 4 weeks after injection and boost injection, respectively. Anti-HBs were assayed in mice sera by ELISA. HBsAg-specific CTL responses of spleen cells from immunized mice were tested by the LDH method.</p><p><b>RESULTS</b>Plasmids of pCI-S and pcDNA3.1-S allowed HBsAg transient expression in cell culture supernatants and cell lysates of HepG2 or COS-7 cells. Intramuscular immunization of BALB/C mice with plasmids of pCI-S or pcDNA3.1-S elicited the antibody and cytotoxic T lymphocyte responses to HBsAg.</p><p><b>CONCLUSIONS</b>The vectors used in this study are effective to induce prime antibody and HBsAg-specific-cytotoxic T lymphocyte responses to HBsAg in mice after intramuscular immunization.</p>