The present invention provides a manufacturing method for polypeptides that are produced in 
insect cells using a baculoviral expression 
system. In one example, the 
insect cell culture is supplemented with a lipid mixture immediately prior to infection (e.g., one hour prior to infection). The polypeptides are isolated from the 
insect cell culture using a method that employs anion exchange or mixed-mode 
chromatography early in the purification process. This process step is useful to remove insect-
cell derived endoglycanases and 
proteases and thus reduces the loss of desired polypeptide due to 
enzymatic degradation. In another example, mixed-mode 
chromatography is combined with dye-ligand 
affinity chromatography in a continuous-flow manner to allow for 
rapid processing of the insect-
cell culture liquid and capture of the polypeptide. In yet another example, a polypeptide is isolated from an 
insect cell culture liquid using a process that combines hollow 
fiber filtration, mixed-mode 
chromatography and dye-ligand affinity in a single 
unit operation producing a polypeptide solution that is essentially free of endoglycanase and proteolytic activities. In a further example, the isolated polypeptides are glycopeptides having an insect specific 
glycosylation pattern, which are optionally conjugated to a modifying group, such as a 
polymer (e.g., PEG) using a 
glycosyltransferase and a modified 
nucleotide sugar.