METHODS:The DNA vaccines, pVR1012-L, pVR1012-M and pVR1012-S, were constructed by inserting HBV envelope gene fragments into plasmid pVR1012. The expression of them in COS7 cell line was examined by Enzyme-linked immunosorbent assay (ELISA) method.

• 方法:构建质粒pVR1012-L；pVR1012-M；pVR1012-S.；转染COS7细胞系进行表达