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Inspired by the role of cell-surface glycoproteins as coreceptors for pathogens, we report the development of GlycoGrip : a glycopolymer-based lateral flow assay for detecting SARS-CoV-2 and its variants. GlycoGrip utilizes glycopolymers for primary capture and antispike antibodies labeled with gold nanoparticles for signal-generating detection. A lock-step integration between experiment and computation has enabled efficient optimization of GlycoGrip test strips which can selectively, sensitively, and rapidly detect SARS-CoV-2 and its variants in biofluids. Employing the power of the glycocalyx in a diagnostic assay has distinct advantages over conventional immunoassays as glycopolymers can bind to antigens in a multivalent capacity and are highly adaptable for mutated strains. As new variants of SARS-CoV-2 are identified, GlycoGrip will serve as a highly reconfigurable biosensor for their detection. Additionally, via extensive ensemble-based docking simulations which incorporate protein and glycan motion, we have elucidated important clues as to how heparan sulfate and other glycocalyx components may bind the spike glycoprotein during SARS-CoV-2 host-cell infection. GlycoGrip is a promising and generalizable alternative to costly, labor-intensive RT-PCR, and we envision it will be broadly useful, including for rural or low-income populations that are historically undertested and under-reported in infection statistics.

The SARS-CoV-2 Omicron sub-lineage contains a significant number of mutations in the spike protein relative to earlier SARS-CoV-2 variants. Most notably, these mutations significantly increased the positive charge of the spike protein that is postulated to confer increased infectivity, potentially through enhanced interactions with cell surface receptors, and an altered host-cell entry mechanism. While heparan sulfate (HS) was shown to be a key co-receptor in the host-cell entry of SARS-CoV-2, the effect of spike charge on its interactions with heparan sulfate has not been clearly elucidated. Here, we investigate the role of evolving spike positive charge in accelerating long-range interactions to heparan sulfate and ACE2 in the glycocalyx. We show that the positively charged Omicron evolved enhanced binding rates to the negatively charged glycocalyx. Moreover, we discovered that while the Omicron spike-ACE2 affinity is comparable to Delta, the Omicron spike interactions with heparan sulfate are significantly enhanced, giving rise to a ternary complex of spike-HS-ACE2 with a larger proportion of double-bound and triple-bound ACE2. Our findings suggest that SARS-CoV-2 variants evolve to be more dependent on heparan sulfate in viral attachment and infection. We leveraged this understanding for the successful and sensitive detection of the Omicron variant. The evolving enhanced binding of SARS-Cov-2 to heparan sulfate presents new therapeutic and diagnostic opportunities.

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