Submitted to: Advances in Virus Research
Publication Type: Literature review
Publication Acceptance Date: 3/5/2006
Publication Date: 10/4/2006
Citation: Harrison, R.L., Jarvis, D.L. 2006. Protein N-Glycosylation in the Baculovirus-Insect Cell Expression System and Engineering of Insect Cells to Produce ³Mammalianized² Recombinant Glycoprotein Advances in Virus Research. Interpretive Summary:
Technical Abstract: Baculovirus expression vectors are frequently used to express glycoproteins, a subclass of proteins that includes many products with therapeutic value. The insect cells that serve as hosts for baculovirus vector infection are capable of transferring oligosaccharide side chains (glycans) to the same sites in recombinant proteins as those that are used for native protein N-glycosylation in mammalian cells. However, while mammalian cells produce compositionally more complex N-glycans containing terminal sialic acids, insect cells mostly produce simpler N-glycans with terminal mannose residues. This structural difference between insect and mammalian N-glycans compromises the in vivo bioactivity of glycoproteins and can potentially induce allergenic reactions in humans. These features obviously compromise the biomedical value of recombinant glycoproteins produced in the baculovirus expression vector system. Thus, much effort has been expended to characterize the potential and limits of N-glycosylation in insect cell systems. Discoveries from this research have led some investigators to engineer insect N-glycosylation pathways to be able to assemble mammalian-style glycans on baculovirus-expressed glycoproteins. This review summarizes our current knowledge of insect N-glycosylation pathways and describes efforts to engineer baculovirus vectors and insect cell lines to overcome the limits of insect cell glycosylation. In addition, we consider other possible strategies for improving glycosylation in insect cells.