Significant role of host sialylated glycans in the infection and spread of severe acute respiratory syndrome coronavirus 2

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been transmitted across all over the world, in contrast to the limited epidemic of genetically- and virologically-related SARS-CoV. However, the molecular basis explaining the difference in the virological characteristics among SARS-CoV-2 and SARS-CoV has been poorly defined. Here we identified that host sialoglycans play a significant role in the efficient spread of SARS-CoV-2 infection, while this was not the case with SARS-CoV. SARS-CoV-2 infection was significantly inhibited by α2-6-linked sialic acid-containing compounds, but not by α2–3 analog, in VeroE6/TMPRSS2 cells. The α2-6-linked compound bound to SARS-CoV-2 spike S1 subunit to competitively inhibit SARS-CoV-2 attachment to cells. Enzymatic removal of cell surface sialic acids impaired the interaction between SARS-CoV-2 spike and angiotensin-converting enzyme 2 (ACE2), and suppressed the efficient spread of SARS-CoV-2 infection over time, in contrast to its least effect on SARS-CoV spread. Our study provides a novel molecular basis of SARS-CoV-2 infection which illustrates the distinctive characteristics from SARS-CoV.

The Glycan-Binding Trait of the Sarbecovirus Spike N-Terminal Domain Reveals an Evolutionary Footprint

“…5C ). These results are in close agreement with previous findings on SARS-CoV-1 and SARS-CoV-2 ( 22 , 47 ). Our data suggest that the sialic acids on the surface of the Calu3 cells inhibit entry of sarbecovirus.…”

“…5A ). This result is generally consistent with the previous studies, and the small difference in SARS-CoV-1 and -2 may be caused by the different cell lines and neuraminidase we used in our experiments ( 22 , 47 ). However, the interfering sialic acids for SARS-CoV-2 are not likely on the viral receptor itself, as blocking O- and N-linked glycan biosynthesis of ACE2 has been shown to have no effect on viral entry or spike binding ( 55 ).…”

“…The sialic acid-binding function in transmissible gastroenteritis virus (TGEV) has been suggested to influence viral pathogenicity ( 14 – 16 ), and computational modeling suggests sialic acid binding in SARS-CoV-2 spike may be an immune evasion mechanism ( 17 ). Recent studies also propose that sialic acid or 9- O -Ac sialic acid of glycoproteins and glycolipids might be served as the host factor for SARS-CoV-2 infection ( 18 – 22 ). However, the functional analysis of this phenotype was not fully assessed in cell culture or animal models, leaving the biological impact unknown.…”

The SARS-CoV-2 spike N-terminal domain engages 9-O-acetylated α2-8-linked sialic acids

“…In-silico structural and molecular studies elaborate that the flat and non-sunken NTD surface of SARS-CoV-2 should allow for sialic acid interactions, enabling viral surfing and dual-receptor functionality of the S1 spike [62-64]. S1 spike interaction with sialic acids has been further shown by four independent studies, however, the contribution of S1-NTD towards sialoside recognition and dual-receptor functionality has not been verified [8, 53, 65, 66].…”

“…Interestingly, when using α2-3-, α2-6- and α2-8-linked O -acetylated sialic acids in our glycan-array, binding was only observed for 9- O -acetyl α2-8-linked sialic acids when using 501Y.V2-1 NTD. Previously inhibition of S1-spike binding was attained with Neu5Ac monosaccharides [23, 66], α2-3 linked [23], (multivalent) α2-6 linked [23, 65] and (multivalent) 9- O -acetylated sialic acid [53], which raises questions regarding the specificity of SARS-CoV-2 NTD towards these structures and whether sufficient receptor binding can be mediated to support a dual-receptor function. Thus, the current reported knowledge indicates that sialic acid binding and multivalency is crucial in infection and tropism whilst the exact glycan partner can vary between coronavirus strains [67].…”