Microfluidic characterisation reveals broad range of SARS-CoV-2 antibody affinity in human plasma
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Abstract
The clinical outcome of SARS-CoV-2 infections, which can range from asymptomatic to lethal, is crucially shaped by the concentration of antiviral antibodies and by their affinity to their targets. However, the affinity of polyclonal antibody responses in plasma is difficult to measure. Here we used microfluidic antibody affinity profiling (MAAP) to determine the aggregate affinities and concentrations of anti–SARS-CoV-2 antibodies in plasma samples of 42 seropositive individuals, 19 of which were healthy donors, 20 displayed mild symptoms, and 3 were critically ill. We found that dissociation constants, K d , of anti–receptor-binding domain antibodies spanned 2.5 orders of magnitude from sub-nanomolar to 43 nM. Using MAAP we found that antibodies of seropositive individuals induced the dissociation of pre-formed spike-ACE2 receptor complexes, which indicates that MAAP can be adapted as a complementary receptor competition assay. By comparison with cytopathic effect–based neutralisation assays, we show that MAAP can reliably predict the cellular neutralisation ability of sera, which may be an important consideration when selecting the most effective samples for therapeutic plasmapheresis and tracking the success of vaccinations.
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SciScore for 10.1101/2020.09.20.20196907: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Ethical and biosafety statement: All experiments and analyses involving samples from human donors were conducted with the approval of the local ethics committee (KEK-ZH-Nr. 2015-0561, BASEC-Nr. 2018-01042, and BASEC-Nr. 2020-01731), in accordance with the provisions of the Declaration of Helsinki and the Good Clinical Practice guidelines of the International Conference on Harmonisation.
Consent: Sample Collection: EDTA plasma from healthy donors and from convalescent individuals was obtained from the Blutspendedienst (blood donation service) Kanton Zürich from donors who signed the consent that their samples can be used for conducting research.Randomization …SciScore for 10.1101/2020.09.20.20196907: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: Ethical and biosafety statement: All experiments and analyses involving samples from human donors were conducted with the approval of the local ethics committee (KEK-ZH-Nr. 2015-0561, BASEC-Nr. 2018-01042, and BASEC-Nr. 2020-01731), in accordance with the provisions of the Declaration of Helsinki and the Good Clinical Practice guidelines of the International Conference on Harmonisation.
Consent: Sample Collection: EDTA plasma from healthy donors and from convalescent individuals was obtained from the Blutspendedienst (blood donation service) Kanton Zürich from donors who signed the consent that their samples can be used for conducting research.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources Then 100 µl of the mixture was subsequently added to the VeroE6 cells in duplicates. VeroE6suggested: JCRB Cat# JCRB1819, RRID:CVCL_YQ49)Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:2 individuals could not be analysed on our platform due to presence of an excessively high serum background fluorescence, a known, yet rare, limitation of our assay20. A size increase, indicating significant binding to the RBD domain, was detected and quantified in all samples (Fig. 2a), with the exception of 6 healthy donor samples which we did not observe binding to the RBD domain by MAAP (Fig. S2). Considering all samples investigated, we found that the antibody concentration for the polyclonal antibody mixture falls into a relatively narrow range of 8-69 nM assuming a binding stoichiometry of 1:2 antibody:RBD, with two exceptions that display relatively high concentrations (192 nM and 298 nM). In contrast, the Kd values were more variable, ranging from subnanomolar (in which case no lower bound on Kd can be determined) to 25 nM (Fig. 2b). From physical considerations in order for significant binding to occur, the antibody binding site concentration must exceed the Kd. Accordingly, our data demonstrate that in all cases where quantifiable binding was detected, [Ab] > 2*Kd (Fig. 2b). Interestingly, also the 3 hospitalised patients displayed affinities and concentrations in a similar range, although their antibody concentration higher than the majority of samples (Fig. 2b). This suggest that the antibody response to a SARS-CoV-2 infection is fairly similar, independent of the symptoms displayed by an individual. We next determined the dissociation constant for the interactio...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
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- No protocol registration statement was detected.
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