Evolution of Anti-RBD IgG Avidity following SARS-CoV-2 Infection.

Abstract

SARS-CoV-2 infection rapidly elicits anti-Spike antibodies whose quantity in plasma gradually declines upon resolution of symptoms. This decline is part of the evolution of an immune response leading to B cell differentiation into short-lived antibody-secreting cells or resting memory B cells. At the same time, the ongoing class switch and antibody maturation processes occurring in germinal centers lead to the selection of B cell clones secreting antibodies with higher affinity for their cognate antigen, thereby improving their functional activity. To determine whether the decline in SARS-CoV-2 antibodies is paralleled with an increase in avidity of the anti-viral antibodies produced, we developed a simple assay to measure the avidity of anti-receptor binding domain (RBD) IgG elicited by SARS-CoV-2 infection. We longitudinally followed a cohort of 29 convalescent donors with blood samples collected between 6- and 32-weeks post-symptoms onset. We observed that, while the level of antibodies declines over time, the anti-RBD avidity progressively increases and correlates with the B cell class switch. Additionally, we observed that anti-RBD avidity increased similarly after SARS-CoV-2 mRNA vaccination and after SARS-CoV-2 infection. Our results suggest that anti-RBD IgG avidity determination could be a surrogate assay for antibody affinity maturation and, thus, suitable for studying humoral responses elicited by natural infection and/or vaccination.

• Authors: Alexandra Tauzin, Gabrielle Gendron-Lepage, Manon Nayrac, Sai Priya Anand, Catherine Bourassa, Halima Medjahed, Guillaume Goyette, Mathieu Dubé, Renée Bazin, Daniel E Kaufmann, Andrés Finzi
• Journal: Viruses (Viruses) Vol. 14 Issue 3 (03 04 2022) ISSN: 1999-4915 [Electronic] Switzerland
• PMID: 35336940 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Viral
• Immunoglobulin G

Topics

• Antibodies, Viral
• COVID-19
• Humans
• Immunoglobulin G
• Protein Binding
• SARS-CoV-2 (genetics)