Use of baculovirus early promoters for expression of foreign genes in stably transformed insect cells

摘要

The present invention provides an alternative strategy for baculovirus-mediated foreign gene expression: the promoters from immediate-early or delayed-early baculovirus viral genes were used to obtain the continuous expression of foreign genes in stably-transformed insect cells. The IE1 or the 30K promoters from Autographa californica nuclear polyhedrosis virus can drive the continuous expression of a foreign gene in insect cells. IE1- beta -galactosidase or 39K- beta -galactosidase constructs were used in combination with the IE1-neomycin resistance construct to cotransfect Spodoptera frugiperda (Sf9) cells. Neomycin-resistant clones were selected and analyzed for beta -galactosidase expression. A high percentage of the transformants expressed beta -galactosidase activity and contained polypeptides which appeared to be authentic beta -galactosidase. Analysis of high molecular weight DNA from the IE1Neo/IE1- beta gal cotransformants showed that plasmid sequences were integrated and maintained for 20-55 passages in culture. Further analysis of the clones expressing beta -galactosidase from the IE1 promoter showed that they contained integrated plasmid DNA sequences and that the beta -galactosidase-encoding transcripts initiated specifically within the IE1 promoter. Thus, early baculovirus promoters may be used for foreign gene expression in stably-transformed insect cells with the advantages of continuous expression and minimal degradation of recombinant protein products.