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Updated: Dec 19, 2025
Detection of SARS-CoV-2 Neutralizing Antibodies using High-Throughput Fluorescent Imaging of Pseudovirus Infection
Published on: June 5, 2021
Neutralizing Antibody Responses to Severe Acute Respiratory Syndrome Coronavirus 2 in Coronavirus Disease 2019
Xiaoli Wang1,2,3, Xianghua Guo4, Qianqian Xin5
1Beijing Center for Disease Prevention and Control, Beijing, China.
Background:
Coronavirus disease 2019 (COVID-19) is a pandemic with no specific antiviral treatments or vaccines. There is an urgent need for exploring the neutralizing antibodies from patients with different clinical characteristics.
Methods:
A total of 117 blood samples were collected from 70 COVID-19 inpatients and convalescent patients. Antibodies were determined with a modified cytopathogenic neutralization assay (NA) based on live severe acute respiratory syndrome coronavirus 2 and enzyme-linked immunosorbent assay (ELISA). The dynamics of neutralizing antibody levels at different time points with different clinical characteristics were analyzed.
Results:
The seropositivity rate reached up to 100.0% within 20 days since onset, and remained 100.0% till days 41-53. The total geometric mean titer was 1:163.7 (95% confidence interval [CI], 128.5-208.6) by NA and 1:12 441.7 (95% CI, 9754.5-15 869.2) by ELISA. The antibody level by NA and ELISA peaked on days 31-40 since onset, and then decreased slightly. In multivariate generalized estimating equation analysis, patients aged 31-45, 46-60, and 61-84 years had a higher neutralizing antibody level than those aged 16-30 years (β = 1.0470, P = .0125; β = 1.0613, P = .0307; β = 1.3713, P = .0020). Patients with a worse clinical classification had a higher neutralizing antibody titer (β = 0.4639, P = .0227).
Conclusions:
The neutralizing antibodies were detected even at the early stage of disease, and a significant response was shown in convalescent patients.
