Advanced Protein Expression Using Bombyx mori Nucleopolyhedrovirus (BmNPV) Bacmid in Silkworm

Abstract

An expression system using a Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid has been developed and used for efficient expression of protein using silkworm. Silkworm can sustain large-scale production of recombinant proteins due to its ease of rearing and scaling-up. Our chapter focuses on the modification of a BmNPV bacmid for a more efficient protein expression system. For example, we discuss how to achieve construction of a stronger promoter, less proteolytic degradation of expressed proteins, and a chaperone-coexpressed expression system. We describe the application of functional BmNPV particles purified from silkworm hemolymph to vaccines, antibody production, and transmembrane protein analysis. For human use, the major problem of proteins produced in silkworm is contamination by adventitious agents and protein quality. Of special concern is that N-glycosylation in silkworms is of a high-mannose type in most cases, which is different from the complex type found in mammals. We end by looking to future prospects for integration/applications of protein expression systems with silkworm biotechnology.