38th Annual Meeting of the Society for Invertebrate Pathology

Insect protein glycosylation pathways appear to be intermediate in complexity relative to lower eucaryotes, such as yeasts, and higher eucaryotes, such as mammals. Insects generally appear to perform the same early steps in protein N-glycosylation, including N-glycan assembly, transfer, and trimming, as lower and higher eucaryotes. However, they generally appear to lack some of the functions required for N-glycan elongation. As a result of this fundamental difference in insect and mammalian cells, recombinant N-glycoproteins produced using the baculovirus-insect cell system typically lack the complex, terminally sialylated glycans of many native mammalian glycoproteins. Instead, insect-derived products typically have paucimannose N-glycans at the sites occupied by complex, terminally sialylated N-glycans in native mammalian N-glycoproteins. We have been addressing this problem by using metabolic engineering methods to extend the protein N-glycosylation pathway of lepidopteran insect cell lines. These efforts have yielded transgenic insect cell lines that encode and express mammalian glycosyltransferases and enzymes involved in CMP-sialic acid biosynthesis. Relative to the parental lines, these new cell lines can still serve as hosts for baculovirus expression vectors and can produce similar levels of recombinant glycoproteins. Unlike the parental insect cell lines, however, the transgenic lines can produce recombinant glycoproteins with complex, terminally sialylated N-glycans. This talk will focus on the creation and characterization of these transgenic insect cell lines.