SARS-CoV-2 Serologic Assays Dependent on Dual-Antigen Binding Demonstrate Diverging Kinetics Relative to Other...

Area of Science:

• Immunology
• Infectious Diseases
• Biochemistry

Background:

• Conflicting results exist regarding the durability of the anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) humoral immune response.
• Discrepancies may stem from varied patient cohorts, non-standardized methods, and assays measuring different humoral response aspects.

Purpose of the Study:

• To longitudinally assess severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody profiles in convalescent plasma donors.
• To compare the performance of eight different commercially available serologic assays over 120 days post-symptom onset.

Main Methods:

• Serial measurement of SARS-CoV-2 antibodies in 44 convalescent plasma donors over 120 days.
• Utilized eight distinct assays varying in antigen source, antibody isotype detection, and measured activity (binding, blocking, neutralizing).
• Focused on assays with Food and Drug Administration emergency use authorization.

Main Results:

• Most assays indicated a gradual decline in antibody titers over 120 days.
• Two Roche electrochemiluminescence immunoassay assays (nucleocapsid and spike-based) showed stable or increasing antibody titers.
• Dual-antigen binding in Roche assays may contribute to sustained antibody detection.

Conclusions:

• SARS-CoV-2 antibody detection is highly dependent on the specific serologic assay employed.
• Assay methodology significantly impacts the interpretation of humoral immune response durability.
• Findings have implications for the clinical utility and future application of serologic assays for COVID-19.