![]() ![]() These glycans confer two benefits on the virus. In addition, the S protein is glycosylated by the host cellular glycosylation apparatus as it passes through the secretory pathway. Therefore, the S protein is a critical determinant of viral host and tissue tropism. The spike protein (S) of coronavirus, which forms large protrusions from the virus surface and gives the virus the appearance of having crowns, mediates virus entry into host cells ( Hu et al., 2020 Cui et al., 2019 Hasöksüz et al., 2020 Virology, 1968). Seven coronavirus strains are known to cause human infection among them, HCoV 229E, HCoV NL63, HCoV HKU1, and HCoV OC43 typically cause only mild upper respiratory diseases in immunocompetent hosts, although some of them can cause severe infections in infants, young children, and elderly individuals ( Cui et al., 2019), while severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and SARS-CoV-2 cause severe respiratory illness and fatalities ( Cui et al., 2019 Hasöksüz et al., 2020). CoVs are responsible for multiple respiratory disorders of varying severity in humans ( Cui et al., 2019). Coronaviruses (CoVs) are enveloped positive-sense RNA viruses, and as a virus with an RNA genome, CoVs have high mutation rates and hence are believed to alter host range and tissue tropism efficiently ( Li, 2016 Cui et al., 2019 Hu et al., 2020). The causative agent was identified to be a member of Betacoronavirus and termed as SARS-CoV-2 ( Coronaviridae Study Group of the International Committee on Taxonomy of Viruses, 2020). Since its first emergence in December 2019, it only took several months before the novel coronavirus disease 2019 (COVID-19), a severe respiratory illness, was declared as a pandemic by the World Health Organization ( ). In this review, we will summarize the roles of S protein glycans in mediating virus–receptor interactions, and in antibody production, as well as indications for vaccine development. On the other hand, while glycan patches on S protein have been reported to shield the host immune response by masking “nonself” viral peptides with “self-glycans,” the epitopes are also important in eliciting neutralizing antibodies. ![]() It is believed that the ongoing COVID-19 pandemic with more than 90,000,000 infections and 1,900,000 deaths is partly due to its successful glycosylation strategy. The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which presents on the surface of matured virion and mediates viral entry into the host, also undergoes extensive glycosylation to shield it from the human defense system. The resulting glycans have unneglectable roles in viral infection and immune response. Viral protein glycosylation represents a successful strategy employed by the parasite to take advantage of host–cell machinery for modification of its own proteins. Department of Pathogen Biology and Immunology, Xi’an Jiaotong University Health Science Center, Xi’an, China.Xiaohui Zhao †, Huan Chen † and Hongliang Wang* ![]()
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