The High Content of Fructose in Human Semen Competitively Inhibits Broad and Potent Antivirals That Target High-Mannose Glycans

Johnson, Jacklyn; Flores, Manuel G; Rosa, J. C.; Han, Changze; Salvi, Alicia M.; DeMali, Kris A.; Jagnow, Jennifer R; Haim, Hillel

doi:10.1128/jvi.01749-19

Cited by 16 publications

(17 citation statements)

References 106 publications

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“…We measured the binding efficiency of anti-NTD antibody AM121 (Acro Biosystems) to the Spike-based constructs using an enzyme-linked immunosorbent assay (ELISA), as previously described (58, 59). For this purpose, the NTD-Fc, RBD-Fc or Spike-Fc suspended in PBS were attached to 96-well protein-binding plates by incubation at isomolar concentrations (2, 1.37 and 5 μg/mL of the probes, respectively).…”

Section: Methods Detailsmentioning

confidence: 99%

Phosphatidylserine Receptors Enhance SARS-CoV-2 Infection: AXL as a Therapeutic Target for COVID-19

Bohan

Ert

Ruggio

et al. 2021

Preprint

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Phosphatidylserine (PS) receptors are PS binding proteins that mediate uptake of apoptotic bodies. Many enveloped viruses utilize this PS/PS receptor mechanism to adhere to and internalize into the endosomal compartment of cells and this is termed apoptotic mimicry. For viruses that have a mechanism(s) of endosomal escape, apoptotic mimicry is a productive route of virus entry. We evaluated if PS receptors serve as cell surface receptors for SARS-CoV-2 and found that the PS receptors, AXL, TIM-1 and TIM-4, facilitated virus infection when low concentrations of the SARS-CoV-2 cognate receptor, ACE2, was present. Consistent with the established mechanism of PS receptor utilization by other viruses, PS liposomes competed with SARS-CoV-2 for binding and entry. We demonstrated that this PS receptor enhances SARS-CoV-2 binding to and infection of an array of human lung cell lines and is an under-appreciated but potentially important host factor facilitating SARS-CoV-2 entry.

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Section: Methods Detailsmentioning

confidence: 99%

Phosphatidylserine Receptors Enhance SARS-CoV-2 Infection: AXL as a Therapeutic Target for COVID-19

Bohan

Ert

Ruggio

et al. 2021

Preprint

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“…We measured the binding efficiency of anti-NTD antibody AM121 (Acro Biosystems) to the Spike-based constructs using ELISA, as previously described [66,67]. For this purpose, the NTD-Fc, RBD-Fc or spike-Fc suspended in PBS were attached to 96-well protein-binding plates by incubation at isomolar concentrations (2, 1.37 and 5 μg/mL of the probes, respectively).…”

Section: Purified Spike Protein Flow Cytometry Binding Studiesmentioning

confidence: 99%

Phosphatidylserine receptors enhance SARS-CoV-2 infection

et al. 2021

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Phosphatidylserine (PS) receptors enhance infection of many enveloped viruses through virion-associated PS binding that is termed apoptotic mimicry. Here we show that this broadly shared uptake mechanism is utilized by SARS-CoV-2 in cells that express low surface levels of ACE2. Expression of members of the TIM (TIM-1 and TIM-4) and TAM (AXL) families of PS receptors enhance SARS-CoV-2 binding to cells, facilitate internalization of fluorescently-labeled virions and increase ACE2-dependent infection of SARS-CoV-2; however, PS receptors alone did not mediate infection. We were unable to detect direct interactions of the PS receptor AXL with purified SARS-CoV-2 spike, contrary to a previous report. Instead, our studies indicate that the PS receptors interact with PS on the surface of SARS-CoV-2 virions. In support of this, we demonstrate that: 1) significant quantities of PS are located on the outer leaflet of SARS-CoV-2 virions, 2) PS liposomes, but not phosphatidylcholine liposomes, reduced entry of VSV/Spike pseudovirions and 3) an established mutant of TIM-1 which does not bind to PS is unable to facilitate entry of SARS-CoV-2. As AXL is an abundant PS receptor on a number of airway lines, we evaluated small molecule inhibitors of AXL signaling such as bemcentinib for their ability to inhibit SARS-CoV-2 infection. Bemcentinib robustly inhibited virus infection of Vero E6 cells as well as multiple human lung cell lines that expressed AXL. This inhibition correlated well with inhibitors that block endosomal acidification and cathepsin activity, consistent with AXL-mediated uptake of SARS-CoV-2 into the endosomal compartment. We extended our observations to the related betacoronavirus mouse hepatitis virus (MHV), showing that inhibition or ablation of AXL reduces MHV infection of murine cells. In total, our findings provide evidence that PS receptors facilitate infection of the pandemic coronavirus SARS-CoV-2 and suggest that inhibition of the PS receptor AXL has therapeutic potential against SARS-CoV-2.

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“…1A). To mimic the native spike trimer on the virus surface, we used a cell-based enzyme linked immunosorbent assay (cbELISA) that measures antibodies against the full-length membrane-bound form of spike (22)(23)(24). For this purpose, we used human osteosarcoma (HOS) cells that express on their surface fusion-competent spike trimers by transfection with an expression plasmid that encodes the full-length protein.…”

Section: Strong Correlations Between Results Of Immunoassays That Apply Different Spike Components As the Capture Antigenmentioning

confidence: 99%

Section: Strong Correlations Between Results Of Immunoassays That Apply Different Spike Components As the Capture Antigenmentioning

confidence: 99%

“…Briefly, HOS cells were seeded in white opaque 96-well plates (1.4 × 10 4 cells per well) and transfected the next day with 80 ng per well of pCG1-SARS-2-S plasmid expressing SARS-CoV-2 spike using JetPrime transfection reagent. To quantify background binding of the antibodies to the cells, a similar number of wells was transfected using a negative control plasmid (∆KS) that does not encode for a viral protein product (23). Three days after transfection, cells were washed with blocking buffer, and serum samples diluted 1,000-fold in blocking buffer were incubated with the cells for one hour at room temperature.…”

Section: Cell-based Elisa Measurements Of Antibodies Against Sars-cov-2 Spikementioning

confidence: 99%

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Limited variation between SARS-CoV-2-infected individuals in domain specificity and relative potency of the antibody response against the spike glycoprotein

Ert

Bohan

Rogers

et al. 2021

Preprint

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The spike protein of SARS-CoV-2 is arranged as a trimer on the virus surface, composed of three S1 and three S2 subunits. Infected and vaccinated individuals generate antibodies against spike, which can neutralize the virus. Most antibodies target the receptor-binding domain (RBD) and N-terminal domain (NTD) of S1; however, antibodies against other regions of spike have also been isolated. The variation between infected individuals in domain specificity of the antibodies and in their relative neutralization efficacy is still poorly characterized. To this end, we tested serum and plasma samples from 85 COVID-19 convalescent subjects using 7 immunoassays that employ different domains, subunits and oligomeric forms of spike to capture the antibodies. Samples were also tested for their neutralization of pseudovirus containing SARS-CoV-2 spike and of replication-competent SARS-CoV-2. We observed strong correlations between the levels of NTD- and RBD-specific antibodies, with a fixed ratio of each type to all anti-spike antibodies. The relative potency of the response (defined as the measured neutralization efficacy relative to the total level of spike-targeting antibodies) also exhibited limited variation between subjects, and was not associated with the overall amount of anti-spike antibodies produced. Accordingly, the ability of immunoassays that use RBD, NTD and different forms of S1 or S1/S2 as capture antigens to estimate the neutralizing efficacy of convalescent samples was largely similar. These studies suggest that host-to-host variation in the polyclonal response elicited against SARS-CoV-2 spike is primarily limited to the quantity of antibodies generated rather than their domain specificity or relative neutralization potency.IMPORTANCEInfection by SARS-CoV-2 elicits antibodies against various domains of the spike protein, including the RBD, NTD and S2. Different infected individuals generate vastly different amounts of anti-spike antibodies. By contrast, as we show here, there is a remarkable similarity in the properties of the antibodies produced. Different individuals generate the same proportions of antibodies against each domain of the spike protein. Furthermore, the relationship between the amount of anti-spike antibodies produced and their neutralization efficacy of SARS-CoV-2 is highly conserved. Therefore, the observed variation in the neutralizing activity of the antibody response in COVID-19 convalescent subjects is caused by differences in the amounts of antibodies rather than their recognition properties or relative antiviral activity. These findings suggest that COVID-19 vaccine strategies that focus on enhancing the overall level of the antibodies will likely elicit a more uniformly efficacious protective response.

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The High Content of Fructose in Human Semen Competitively Inhibits Broad and Potent Antivirals That Target High-Mannose Glycans

Cited by 16 publications

References 106 publications

Phosphatidylserine Receptors Enhance SARS-CoV-2 Infection: AXL as a Therapeutic Target for COVID-19

Phosphatidylserine Receptors Enhance SARS-CoV-2 Infection: AXL as a Therapeutic Target for COVID-19

Phosphatidylserine receptors enhance SARS-CoV-2 infection

Limited variation between SARS-CoV-2-infected individuals in domain specificity and relative potency of the antibody response against the spike glycoprotein

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