Expression of Bombyx Family Fungal Protease Inhibitor F from Bombyx mori by Baculovirus Vector

Abstract

Fungal protease inhibitor F (FPI-F) from silkworm hemolymph is a novel serine protease inhibitor of the Bombyx family. The cDNA of FPI-F was introduced into a baculovirus vector and a recombinant virus was isolated and plaque-purified. The protease inhibitory activities increased in the culture medium of insect cells and in the hemolymph of silkworms infected with the recombinant virus. Judged from the behavior on ion-exchange and reversed-phase chromatographies, amino acid compositions, amino-terminal sequences, and CD spectra, the recombinant FPI-F was identical with native FPI-F. Infection with the recombinant virus caused inhibition of larval development of the silkworm. However, the degree of the effect was different in two strains, Shinryukaku and Taiheichoan, indicating that the selection of the strain of silkworm is important in using the baculovirus expression system.