A construction strategy for a baculovirus-silkworm multigene expression system and its application for coexpression of type I and type II interferons

The Bombyx mori nucleopolyhedrovirus (BmNPV) baculovirus expression system (BES) is a eukaryotic expression system. It possesses great capability for post-translation modification in expression of foreign proteins. With the counterselection cassette rpsL-neo and phage lambda-Red recombinase, the defective-rescue BmNPV BES reBmBac can be employed for efficient heterologous multigene coexpression at different gene sites in one baculovirus genome. In the present study, a recombinant baculovirus, reBm-C alpha gamma, carrying two types of chicken interferon (IFN) genes (chIFN-alpha and chIFN-gamma) was constructed using the reBmBac system. The chIFN-alpha and chIFN-gamma genes were inserted into the same baculovirus genome at the polyhedron and p10 gene sites, respectively. The recombinant baculovirus was capable of coexpressing both chIFN-alpha and chIFN-gamma. The expression levels of the two types of IFN in the coexpression product were exponentially high, at approximately 1.7 and 2.5 times higher, respectively, than those in the corresponding single-expression products. The increase in expression level corresponds to replacement of the nonessential p10 gene in the reBm-C alpha gamma recombinant baculovirus. This coexpression of recombinant chicken IFNs showed superior antiviral activity.