Antibody Binding and Angiotensin-Converting Enzyme 2 Binding Inhibition Is Significantly Reduced for Both the BA.1 and BA.2 Omicron Variants.

Background: The rapid emergence of the Omicron variant and its large number of mutations led to its classification as a variant of concern (VOC) by the World Health Organization. Subsequently, Omicron evolved into distinct sublineages (eg, BA.1 and BA.2), which currently represent the majority of global infections. Initial studies of the neutralizing response toward BA.1 in convalescent and vaccinated individuals showed a substantial reduction.
Methods: We assessed antibody (immunoglobulin G [IgG]) binding, ACE2 (angiotensin-converting enzyme 2) binding inhibition, and IgG binding dynamics for the Omicron BA.1 and BA.2 variants compared to a panel of VOCs/variants of interest, in a large cohort (N = 352) of convalescent, vaccinated, and infected and subsequently vaccinated individuals.
Results: While Omicron was capable of efficiently binding to ACE2, antibodies elicited by infection or immunization showed reduced binding capacities and ACE2 binding inhibition compared to wild type. Whereas BA.1 exhibited less IgG binding compared to BA.2, BA.2 showed reduced inhibition of ACE2 binding. Among vaccinated samples, antibody binding to Omicron only improved after administration of a third dose.
Conclusions: Omicron BA.1 and BA.2 can still efficiently bind to ACE2, while vaccine/infection-derived antibodies can bind to Omicron. The extent of the mutations within both variants prevents a strong inhibitory binding response. As a result, both Omicron variants are able to evade control by preexisting antibodies.
Competing Interests: Potential conflicts of interest. N. S. M. was a speaker at previous Luminex user meetings. The NMI is involved in applied research projects as a fee for services with the Luminex Corporation. M. Bi. reports payment or honoraria from MSD Sharp & Dohme GmbH for symposia; and also reports participation on advisory boards for Roche Pharma AG, Incyte Biosciences Germany GmbH, Bayer Vital GmbH, Bristol-Myers Squibb GmbH & Co KgaA, and MSD Sharp & Dohme GmbH. C. E. reports support for the present manuscript from MWK Sonderfördermaßnahme Kinderstudie (Kap. 1499 TG 93). B. L. reports receiving funding for the present manuscript from NaFOUniMedCovid19 (FKZ: 01KX2021) supported by the German Federal Ministry of Education and Research; and reports a leadership or fiduciary role for the German Center for Infection Research (TI BBD, DZIF), Transplant Cohort, and Steering Committee TBNet. A. Z. reports state technology funding for device infrastructure (7-4332.62-NMI/55), outside the conduct of this study. N. S.-M. reports support for the present manuscript from LAND BW (MULTICOV-AB and LAND BW, Automation in SARS-CoV-2) and payment or honoraria from Luminex Corporation for being a speaker at previous user meetings (the NMI is also involved in applied research projects as a fee for services with the Luminex Corporation). All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
(© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)