EFFICIENT GENERATION OF INFECTIOUS RECOMBINANT BACULOVIRUSES BY SITE-SPECIFIC TRANSPOSON-MEDIATED INSERTION OF FOREIGN GENES INTO A BACULOVIRUS GENOME PROPAGATED IN ESCHERICHIA-COLI

The construction and purification of recombinant baculovirus vectors f or the expression of foreign genes in insect cells by standard transfe ction and plaque assay methods can take as long as 4 to 6 weeks. This period can be reduced to several days by using a novel baculovirus shu ttle vector (bacmid) that can replicate in Escherichia coli as a plasm id and can infect susceptible lepidopteran insect cells. The bacmid is a recombinant virus that contains a mini-F replicon, a kanamycin resi stance marker, and attTn7, the target site for the bacterial transposo n Tn7. Expression cassettes comprising a baculovirus promoter driving expression of a foreign gene that is flanked by the left and right end s of Tn7 can transpose to the target bacmid in E. coli when Tn7 transp osition functions are provided in trans by a helper plasmid. The forei gn gene is expressed when the resulting composite bacmid is introduced into insect cells.