[Using BPV transforming foci as selective markers to express HBsAg]

We constructed a plasmid pBMTHBR2 containing mouse MT promoter, entire HBsAg gene (preS and S gene), splicing signal from SV40 and complete BPV genome. Using calcium phosphate precipitation technique to transform C127 Cells and using BPV transforming foci as selective markers, we obtained transformed cell clones. The experiment shows that 57% of the cloned cell lines can secrete HBsAg continuously.