Open AccessN-Linked Glycosylation Plays an Important Role in Budding of Neuraminidase Protein and Virulence of Influenza Viruses
Author(s) -
Dan Bao,
Ruixue Xue,
Min Zhang,
Chenyang Lu,
Tianxin Ma,
ChunXia Ren,
Ting Zhang,
Jianmei Yang,
Quincy Teng,
Xuesong Li,
Zejun Li,
Qinfang Liu
Publication year - 2021
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.02042-20
Subject(s) - biology , virulence , neuraminidase , virology , glycosylation , budding , h5n1 genetic structure , glycoprotein , influenza a virus , microbiology and biotechnology , influenza a virus subtype h5n1 , orthomyxoviridae , virus , gene , genetics , covid-19 , infectious disease (medical specialty) , medicine , disease , pathology
Neuraminidase (NA) has multiple functions in the life cycle of influenza virus, especially in the late stage of virus replication. Both of hemagglutinin (HA) and NA are highly glycosylated proteins. N-linked glycosylation (NLG) of HA has been reported to contribute to immune escape and virulence of influenza viruses. However, the function of NLG of NA remains largely unclear. In this study, we found that NLG is critical for budding ability of NA. Tunicamycin treatment or NLG knockout significantly inhibited the budding of NA. Further studies showed that the NLG knockout caused attenuation of virus in vitro and in vivo Notably, the NLG at 219 position plays an important role in the budding, replication, and virulence of H1N1 influenza virus. To explore the underlying mechanism, the unfolded protein response (UPR) was determined in NLG knockout NA overexpressed cells, which showed that the mutant NA was mainly located in the endoplasmic reticulum (ER), the UPR markers BIP and p-eIF2α were upregulated, and XBP1 was downregulated. All the results indicated that NLG knockout NA was stacked in the ER and triggered UPR, which might shut down the budding process of NA. Overall, the study shed light on the function of NLG of NA in virus replication and budding. IMPORTANCE NA is a highly glycosylated protein. Nevertheless, how the NLG affects the function of NA protein remains largely unclear. In this study, we found that NLG plays important roles in budding and Neuraminidase activity of NA protein. Loss of NLG attenuated viral budding and replication. In particular, the 219 NLG site mutation significantly attenuated the replication and virulence of H1N1 influenza virus in vitro and in vivo , which suggested that NLG of NA protein is a novel virulence marker for influenza viruses.