MODIFYING THE INSECT-CELL N-GLYCOSYLATION PATHWAY WITH IMMEDIATE-EARLY BACULOVIRUS EXPRESSION VECTORS

The baculovirus-insect cell expression system is well-suited for recom binant glycoprotein production because baculovirus vectors can provide high levels of expression and insect cells can modify newly synthesiz ed proteins in eucaryotic fashion. However, the N-glycosylation pathwa y of baculovirus-infected insect cells differs from the pathway found in higher eucaryotes, as indicated by the fact that glycoproteins prod uced in the baculovirus system typically lack complex biantennary N-li nked oligosaccharide side chains containing penultimate galactose and terminal sialic acid residues. We recently developed a new type of bac ulovirus vector that cart express foreign genes immediately after infe ction under the control of the viral ie1 promoter. These immediate ear ly baculovirus expression vectors can be used to modify the insect cel l N-glycosylation pathway and produce a foreign glycoprotein with more extensively processed N-linked oligosaccharides, These vectors can al so be used to study the influence of the late steps in N-linked oligos accharide processing on glycoprotein function. Further development cou ld lead to baculovirus-insect cell expression systems that can produce recombinant glycoproteins with complex biantennary N-linked oligosacc harides structurally identical to those produced by higher eucaryotes.