High expression of human chorionic gonadotrophin β-subunit using a synthetic vaccinia virus promoter

Abstract

We have constructed a recombinant vaccinia virus to express the β-subunit of human chorionic gonadotrophin (βhCG), a secretory glycoprotein that is used as an antigen for a contraceptive vaccine. The cDNA encoding the subunit was cloned under the control of a synthetic promoter that could be recognised by a vaccinia virus RNA polymerase to direct transcription. The peak expression level of βhCG directed by a late synthetic promoter (Psyn) was 11·5 μg/ml, a level that was at least sixfold higher than that directed by the p7·5 early/late promoter. The expressed protein was correctly processed post-translationally such that it attained a conformation with correctly folded discontinous epitope(s) similar to that seen in native βhCG.