Affinity of anti-spike antibodies in SARS-CoV-2 patient plasma and its effect on COVID-19 antibody assays.
EBioMedicine
; 75: 103796, 2022 Jan.
Article
em En
| MEDLINE
| ID: mdl-34971970
ABSTRACT
BACKGROUND:
Measuring anti-spike protein antibodies in human plasma or serum is commonly used to determine prior exposure to SARS-CoV-2 infection and to assess the anti-viral protection capacity. According to the mass-action law, a lesser concentration of tightly binding antibody can produce the same quantity of antibody-antigen complexes as higher concentrations of lower affinity antibody. Thus, measurements of antibody levels reflect both affinity and concentration. These two fundamental parameters cannot be disentangled in clinical immunoassays, and so produce a bias which depends on the assay format.METHODS:
To determine the apparent affinity of anti-spike protein antibodies, a small number of antigen-coated magnetic microparticles were imaged by fluorescence microscopy after probing antigen-antibody equilibria directly in patient plasma. Direct and indirect anti-SARS-CoV-2 immunoassays were used to measure antibody levels in the blood of infected and immunised individuals.FINDINGS:
We observed affinity maturation of antibodies in convalescent and vaccinated individuals, showing that higher affinities are achieved much faster by vaccination. We demonstrate that direct and indirect immunoassays for measuring anti-spike protein antibodies depend differently on antibody affinity which, in turn, affects accurate interpretation of the results.INTERPRETATION:
Direct immunoassays show substantial antibody affinity dependence. This makes them useful for identifying past SARS-CoV-2 exposure. Indirect immunoassays provide more accurate quantifications of anti-viral antibody levels.FUNDING:
The authors are all full-time employees of Abbott Laboratories. Abbott Laboratories provided all operating funds. No external funding sources were used in this study.Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Glicoproteína da Espícula de Coronavírus
/
SARS-CoV-2
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COVID-19
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Anticorpos Antivirais
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Afinidade de Anticorpos
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Antígenos Virais
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article