A baculovirus vector can express intron-containing genes.

A simjan virus 40 genomic fragment containing the genes coding for the large T and small t antigens was inserted into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus downstream of the strong polyhedrin promoter. Infection of eucaryotic Spodoptera frugiperda (SF9) cells with this recombinant virus produced significant amounts of small t antigen and little or no large T protein. Analysis by Northern blotting and S1 nuclease digestion revealed correct and preferential utilization of the small t splicing signals.