Intact Glycopeptide Analysis of Influenza A/H1N1/09 Neuraminidase Revealing the Effects of Host and Glycosite Location on Site-Specific Glycan Structures.

Influenza H1N1 virus has posed a serious threat to human health. The glycosylation of neuraminidase (NA) could affect the infectivity and virulence of the influenza virus, but detailed site-specific glycosylation information of NA is still missing. In this study, intact glycopeptide analysis is performed on an influenza NA (A/H1N1/California/2009) that is expressed in human 293T and insect Hi-5 cells. The data indicate that three of four potential N-linked glycosylation sites are glycosylated, including one partial glycosylation site from both cell lines. The NA expressed in human cells has more complex glycans than that of insect cells, suggesting the importance of selecting an appropriate expression system for the production of functional glycoproteins. Different types of glycans are identified from different glycosites of NA expressed in human cells, which implies the site-dependence of glycosylation on NA. This study provides valuable information for the research of influenza virus as well as the functions of viral protein glycosylation.