The D614G mutation confers an advantage for infectivity by increasing the stability of virions 17 and inducing structural changes that favor hACE2 binding 18. For example, the spike amino acid D614G mutation was rare before March 2020 but was noted to be increasing in frequency in April 2020. Since its emergence, CoV2 has evolved continuously, accumulating multiple spike mutations as an adaptation mechanism to escape from immune selection pressure 16. CoV2-S is also the principal target of neutralizing antibodies elicited by the infection 14, 15.
S1 includes the receptor-binding domain (RBD) responsible for the virus-host cell interaction, whereas S2 mediates membrane fusion activity 11, 12, 13. The SARS-CoV-2 spike protein (CoV2-S) is trimeric, with each monomer consisting of S1 and S2 subunits 9, 10. CoV2 utilizes the human enzyme angiotensin-converting enzyme 2 (hACE2) as a cell receptor 8, 9. Although the Delta variant (B.1.617.2 lineage) had dominated previous variants and had spread widely to >180 countries by September 2021, the newly emerging Omicron variant (B.1.1.529.2/BA.2 lineage) outcompeted the Delta variant and swiftly became the dominant strain worldwide as of January 2022 7. Severe acute respiratory syndrome coronavirus 2 (CoV2), which is responsible for coronavirus disease 19 (COVID-19) is causing an ongoing global health problem 4, 5, 6. Some viruses use glycans on host cells to increase the possibility of viral adsorption onto the host cell, whereas other viruses use glycans as viral entry receptors. It is known that viruses utilize glycans in various ways when infecting a host cell 3. Surface proteins on both cellular and viral membranes are glycosylated by the host cellular glycosylation apparatus these glycans are extremely diverse and highly species-specific 2. Two-thirds of animal viruses possess a membrane similar to that of the host cell 1.
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