Patent ID: 8110183

Claim:
A method for sustained expression of an exogenous gene, comprising: providing a first recombinant baculovirus comprising a first expression cassette including a recombinase gene; providing a second recombinant baculovirus comprising a second expression cassette, wherein the second expression cassette includes two recombinase recognition sites and an exogenous gene cassette flanked by the recombinase recognition sites, wherein the exogenous gene cassette comprises an origin of replication sequence; and co-transducing the first recombinant baculovirus and the second recombinant baculovirus to a mammalian cell, whereby the first expression cassette and the second expression cassette are introduced into the mammalian cell, wherein a recombinase expressed by the recombinase gene recognizes and cuts the recombinase recognition sites of the second expression cassette; the second expression cassette is cleaved off from the genome of the second recombinant baculovirus; and the cut recombinase recognition sites of the separated second expression cassette comprising the exogenous gene cassette are self-ligated to form a circular episomal plasmid consisting of one recombinase recognition site and the exogenous gene cassette for sustained expression of the exogenous gene cassette.