Improvement of the transcriptional strength of baculovirus very late polyhedrin promoter by repeating its untranslated leader sequences and coexpression with the primary transactivator.

Modified polyhedrin promoter (Ppolh) was designed by repeating burst sequences (BSs) and adopted to overexpress rat α2,6-sialyltransferase (ST6Gal I) in silkworm. Modified Ppolh of five BSs with VLF-1 coexpression yielded 2.9 U/ml ST6Gal I activity and 32.5 mU/mg specific activity, which was 1.7- and 2.3-fold higher, respectively compared to Ppolh.