High-level expression of human acidic fibroblast growth factor and basic fibroblast growth factor in silkworm (Bombyx mori L.) using recombinant baculovirus

A hybrid of Autographa californica nuclear polyhedrosis virus and Bombyx mo ri nuclear polyhedrosis virus, which is infectious to both Spodoptera frugi perda and Bombyx mori, was prepared in our previous study. Two recombinant hybrid baculoviruses, carrying cDNAs of human acidic and basic fibroblast g rowth factors, respectively, were successfully constructed in this study, f or the large-scale production of human aFGF and bFGF using silkworm as host . These recombinant viruses were used to inoculate silkworm larvae. After t he infection, the recombinant proteins were not found in the hemolymph. Suc h nonsecretion from cells has also been observed in the established insect cell lines, Sf21 and Tn-5. Tissue distribution analysis indicated that the expressed products were mainly located in fat body and the production of th e recombinant aFGF and bFGF was maximal at around 80 h postinfection. There fore, silkworm larvae infected with recombinant viruses were dissected and fat bodies were collected for the purification of recombinant aFGF and bFGF . The expression levels in both cases were estimated to be as high as appro ximately 600-700 mug per larva. Furthermore, the recombinant proteins were characterized and their biological activities were evaluated by in vitro bi oassay using cell culture. (C) 2001 Academic Press.