A human monoclonal antibody bivalently binding two different epitopes in streptococcal M protein protects against infection

Bahnan, Wael; Happonen, Lotta; Khakzad, Hamed; Ahnlide, Vibha Kumra; Neergaard, Therese de; Wrighton, Sebastian; Bratanis, Eleni; Tang, Di; Hellmark, Thomas; Björck, Lars; Shannon, Oonagh; Malmström, Lars; Malmström, Johan; Nordenfelt, Pontus

doi:10.1101/2021.03.01.433494

Cited by 7 publications

(6 citation statements)

References 79 publications

(103 reference statements)

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“…To further explore sources of uncertainty in site localization measurements, the antibody binding sites were measured with secondary antibody labelling and compared to direct labelling ( Figure 4—figure supplement 2 ). The presented results are consistent with the arrangement of the binding sites as reported in the literature ( Akesson et al, 1994 ; Bahnan et al, 2021 ; Hauri et al, 2019 ).…”

Section: Resultssupporting

confidence: 92%

“…The antibody Fc binding site on M protein is located at the S region ( Akesson et al, 1994 ), and a non-specific monoclonal IgG antibody (Xolair) is used for site localization of this binding. Additionally, a measurement is carried out for an M protein-specific mAb, Ab49 ( Bahnan et al, 2021 ), with an epitope located in the B3-S region, that is, slightly further along the IgGFc binding region. For determining binding to the far end of M protein, we used fibrinogen that has two binding sites at the B1 and B2 region ( Hauri et al, 2019 ).…”

Section: Resultsmentioning

confidence: 99%

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Nanoscale binding site localization by molecular distance estimation on native cell surfaces using topological image averaging

Ahnlide

Wrighton

et al. 2022

eLife

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Antibody binding to cell surface proteins plays a crucial role in immunity, and the location of an epitope can altogether determine the immunological outcome of a host-target interaction. Techniques available today for epitope identification are costly, time-consuming, and unsuited for high-throughput analysis. Fast and efficient screening of epitope location can be useful for the development of therapeutic monoclonal antibodies and vaccines. Cellular morphology typically varies, and antibodies often bind heterogeneously across a cell surface, making traditional particle-averaging strategies challenging for accurate native antibody localization. In the present work, we have developed a method, SiteLoc, for imaging-based molecular localization on cellular surface proteins. Nanometer-scale resolution is achieved through localization in one dimension, namely, the distance from a bound ligand to a reference surface. This is done by using topological image averaging. Our results show that this method is well suited for antibody binding site measurements on native cell surface morphology and that it can be applied to other molecular distance estimations as well.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Nanoscale binding site localization by molecular distance estimation on native cell surfaces using topological image averaging

Ahnlide

Wrighton

et al. 2022

eLife

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“…Crosslinking of antibodies to Spike protein For the crosslinking of the antibodies to the Spike protein, 2 uG of each antibody was separately cross-linked to 2 uG of the Spike protein (Sino Biological Inc. 40589-V08H4 LC14SE2504, Recombinant SARS CoV-2 (1029-nCoV) Spike), as previously described (42). Briefly, the proteins were allowed to bind to each other in 50 uL of 1xPBS, pH 7.4 at 37 °C, 500 rpm, 15 min.…”

Section: Methodsmentioning

confidence: 99%

Opsonization by non-neutralizing antibodies can confer protection to SARS-CoV-2 despite Spike-dependent modulation of phagocytosis

Bahnan

Wrighton

Sundwall

et al. 2021

Preprint

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Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on non-neutralizing antibodies. Antibody-dependent phagocytosis is an immune mechanism enhanced by opsonization, where typically, more bound antibodies trigger a stronger phagocyte response. Here, we show that Spike-specific antibodies, dependent on concentration, can either enhance or reduce Spike-bead phagocytosis by monocytes independently of the antibody neutralization potential. Surprisingly, we find that both convalescent patient plasma and patient-derived monoclonal antibodies lead to maximum opsonization already at low levels of bound antibodies and is reduced as antibody binding to Spike protein increases. Moreover, we show that this Spike-dependent modulation of opsonization seems to affect the outcome in an experimental SARS-CoV-2 infection model. These results suggest that the levels of anti-Spike antibodies could influence monocyte-mediated immune functions and propose that non-neutralizing antibodies could confer protection to SARS-CoV-2 infection by mediating phagocytosis.

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“…To study Fab and Fc binding independently, IdeS cleaved monoclonal antibodies are used. The Fab binding is studied using a specific antibody to M protein [αM, (25)] and a human IgG clone with no specificity to M protein (Xolair) is used for the Fc-binding.…”

Section: Biophysical Modeling Of Competitive Antibody Binding To M Prmentioning

confidence: 99%

“…Xolair (Omalizumab, Novartis) is a humanized monoclonal IgG that is IgE-specific, and thus only binds to M protein via Fc. αM is an M protein specific antibody (25). Based on reference values, the concentration of IgG in full serum was set to 10 mg/ml (34).…”

Section: Antibody Preparationmentioning

confidence: 99%

A Predictive Model of Antibody Binding in the Presence of IgG-Interacting Bacterial Surface Proteins

et al. 2021

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Many bacteria can interfere with how antibodies bind to their surfaces. This bacterial antibody targeting makes it challenging to predict the immunological function of bacteria-associated antibodies. The M and M-like proteins of group A streptococci (GAS) exhibit IgGFc-binding regions, which they use to reverse IgG binding orientation depending on the host environment. Unraveling the mechanism behind these binding characteristics may identify conditions under which bound IgG can drive an efficient immune response. Here, we have developed a biophysical model for describing these complex protein-antibody interactions. We show how the model can be used as a tool for studying the binding behavior of various IgG samples to M protein by performing in silico simulations and correlating this data with experimental measurements. Besides its use for mechanistic understanding, this model could potentially be used as a tool to aid in the development of antibody treatments. We illustrate this by simulating how IgG binding to GAS in serum is altered as specified amounts of monoclonal or pooled IgG is added. Phagocytosis experiments link this altered antibody binding to a physiological function and demonstrate that it is possible to predict the effect of an IgG treatment with our model. Our study gives a mechanistic understanding of bacterial antibody targeting and provides a tool for predicting the effect of antibody treatments in the presence of bacteria with IgG-modulating surface proteins.

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A human monoclonal antibody bivalently binding two different epitopes in streptococcal M protein protects against infection

Cited by 7 publications

References 79 publications

Nanoscale binding site localization by molecular distance estimation on native cell surfaces using topological image averaging

Nanoscale binding site localization by molecular distance estimation on native cell surfaces using topological image averaging

Opsonization by non-neutralizing antibodies can confer protection to SARS-CoV-2 despite Spike-dependent modulation of phagocytosis

A Predictive Model of Antibody Binding in the Presence of IgG-Interacting Bacterial Surface Proteins

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