Baculovirus infection does not alter N-glycosylation in Spodoptera frugiperda cells

Spodoptera frugiperda cells are the standard host system for baculovirus-vector-mediated expression of recombinant glycoproteins. In an attempt to explore their ability to produce complex N-glycans containing terminal neuraminic acid, we tested both mock- and AcMNPV-infected SF9 cells. To elucidate the structures of the carbohydrate chains of cellular glycoproteins, radiolabeled oligosaccharides were liberated by treatment with endo-H and glycopeptidase F. When the endo-H resistant material was subjected to sequential degradation with exoglycosidases, only truncated carbohydrates with the structures Man3GlcNAc2 and Man3[Fuc]GlcNAc2 were found. There was no evidence for the presence of neuraminic acid and complex N-glycans. The results indicate that SF9 cells have only a limited capacity to process N-glycans. Infection with AcMNPV has no significant effect on glycosylation in these cells.