Polyvalent Nano-Lectin Potently Neutralizes SARS-CoV-2 by Targeting Glycans on the Viral Spike Protein

Abstract

Mutations in spike (S) protein epitopes allow SARS-CoV-2 variants to evade antibody responses induced by infection and/or vaccination. In contrast, mutations in glycosylation sites across SARS-CoV-2 variants are very rare, making glycans a potential robust target for developing antivirals. However, this target has not been adequately exploited for SARS-CoV-2, mostly due to intrinsically weak monovalent protein–glycan interactions. We hypothesize that polyvalent nano-lectins with flexibly linked carbohydrate recognition domains (CRDs) can adjust their relative positions and bind multivalently to S protein glycans, potentially exerting potent antiviral activity. Herein, we displayed the CRDs of DC-SIGN, a dendritic cell lectin known to bind to diverse viruses, polyvalently onto 13 nm gold nanoparticles (named G13-CRD). G13-CRD bound strongly and specifically to target glycan-coated quantum dots with sub-nM K d. Moreover, G13-CRD neutralized particles pseudotyped with the S proteins of Wuhan Hu-1, B.1, Delta variant and Omicron subvariant BA.1 with low nM EC50. In contrast, natural tetrameric DC-SIGN and its G13 conjugate were ineffective. Further, G13-CRD potently inhibited authentic SARS-CoV-2 B.1 and BA.1, with <10 pM and <10 nM EC50, respectively. These results identify G13-CRD as the 1st polyvalent nano-lectin with broad activity against SARS-CoV-2 variants that merits further exploration as a novel approach to antiviral therapy.

Probing scaffold size effects on multivalent lectin–glycan binding affinity, thermodynamics and antiviral properties using polyvalent glycan-gold nanoparticles

“…19 Finally, the LA-EG 4 -acetylene linker was efficiently coupled to N 3 -EG 2 -DiMan or N 3 -EG 2 -OH (commercial) via the Cu-catalyzed click chemistry to give the desired LA-EG 4 -DiMan or LA-EG 4 -OH ligand in good yields, respectively. 11,43 Their chemical structures were confirmed by 1 H/ 13 C NMR and LC-MS spectra (see ESI section 3† for details).…”

“…These results clearly indicated that the observed inhibitions were specific, due to the specific binding of G x -DiMan to cell surface DC-SIGN/R receptors which blocked their subsequent binding to EBOV-GP to augment viral infection. The normalized viral inhibition data were fitted by a modified inhibition model described in eqn (9): 11,43 where NA, EC 50 , C , and n are the normalized luciferase activity, G x -DiMan concentration giving 50% apparent inhibition, G x -DiMan concentration, and inhibition coefficient, respectively. Here, the n value indicates how quickly an inhibitor can achieve complete inhibition by increasing the concentration, with n < 1, =1, or >1 indicating that the inhibition is negatively-, non- or positively-cooperative, respectively.…”

“…Here, the n value indicates how quickly an inhibitor can achieve complete inhibition by increasing the concentration, with n < 1, =1, or >1 indicating that the inhibition is negatively-, non- or positively-cooperative, respectively. 43 In general, any viable viral inhibitors should have n ≥ 1 (with n = 1 being the most widely observed), so that they can completely inhibit virus infection at a reasonable concentration. 43 The normalised luciferase activities (indicative of viral infections) for samples after each G x -DiMan treatment were plotted against the G x -DiMan concentration and fitted using eqn (9) as shown in Fig.…”

Probing the pH-dependency of DC-SIGN/R multivalent lectin–glycan interactions using polyvalent glycan-gold nanoparticles

“…The LA–EG 4 –DiMan ligand was synthesised by Cu-catalysed click chemistry between a LA–EG 4 –acetylene linker and N 3 –EG 2 –DiMan and purified by using a P2 biogel column as reported previously. 20,40 Details of the ligand synthesis and purification procedures and its spectroscopic characterisation are provided in the ESI, Fig. S3†.…”

In Situ Glycan Analysis and Editing in Living Systems

“…The well-established disadvantages of lectins are their weak binding to monosaccharides and generally low specificity. − In addition, the recognition events usually alter cell signaling pathways . The artificial construction of tandem repeat lectins as novel multivalent receptors can greatly enhance the affinity for glycan ligands. − Given the extensive repertoire of lectins (more than a hundred have been commercialized), their advantages in the simultaneous detection of multiple glycans are unmatched by other methods (Figure a). , Recently, lectin–glycan recognition has been integrated into new single-cell sequencing technologies (Figure b) − to elucidate the functions of glycans in cell–cell and cell–microbe communication, reveal cellular heterogeneity in glycans, and facilitate cell typing according to glycan levels.…”