Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulins using chemiluminescence immunoassay and its correlation with neutralizing antibodies

Yasmine Gaber; Shereen Abdel Alem; Sherief Musa; Khaled Amer; Tarek Elnagdy; Wael A Hassan; Raafat Zaher Abdelrahman; Ahmed Gad; Mohamed A Ali; Hedy A Badary; Shereen Shawky; Hala Talaat; Abdel Meguid Kassem; Rabab Fouad

doi:10.1016/j.virusres.2022.198852

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulins using chemiluminescence immunoassay and its correlation with neutralizing antibodies

Virus Res. 2022 Oct 2:319:198852. doi: 10.1016/j.virusres.2022.198852. Epub 2022 Jul 11.

Authors

Affiliations

¹ Endemic Medicine Department, Kasr Al-Aini Faculty of Medicine, Faculty of Medicine, Cairo University, Cairo, Egypt. Electronic address: yasmin.mohamed@cu.edu.eg.
² Endemic Medicine Department, Kasr Al-Aini Faculty of Medicine, Faculty of Medicine, Cairo University, Cairo, Egypt.
³ Egypt Center for Research and Regenerative Medicine (ECRRM), Cairo, Egypt.
⁴ Armed Forces Laboratories for Medical Research and Blood Bank, Egypt.
⁵ Center of Scientific Excellence for Influenza Viruses, National Research Center, Giza, Egypt.
⁶ Clinical Pathology Department, Kasr Al-Aini Faculty of Medicine, Cairo University, Cairo, Egypt.
⁷ Department of Pediatrics, Kasr Al-Aini Faculty of Medicine, Cairo University, Cairo, Egypt.

Abstract

Background: Neutralizing antibodies (NAbs) against SARS-CoV-2 infection have a pivotal role in protective immune response; however, their measurement requires specialized facilities. We evaluated the degree of correlation between NAbs and anti-SARS-CoV-2 IgG/total Ig antibodies detected by chemiluminescent immunoassay in asymptomatic and previously symptomatic SARS-CoV-2 patients.

Methods: A total of 1241 participants (previously symptomatic patients and asymptomatic individuals), who were screened for SARS-CoV-2 infection by RT-PCR or serology, were enrolled in our study. Sera were analyzed for the presence of anti-spike-1(S1)-SARS-CoV-2 IgG/total Ig antibodies, using Ortho Clinical Diagnostics, USA. A signal/cut-off value (S/CO) ≥ 1 was considered reactive. NAbs were measured in 103 random samples from groups using microneutralization assay, with titer ≥ 1:10 being considered positive.

Results: Asymptomatic (n = 229) and 261 previously symptomatic individuals with positive serology and negative RT-PCR were finally included. Significant higher anti-S1-IgG titers were seen in asymptomatic individuals (P < 0.0001). Conversely, anti-S1-total Ig titers were significantly higher in previously symptomatic (P < 0.0001). NAbs were detected in both groups, however, higher titers were seen in previously symptomatic patients. There is a correlation between NAbs and both IgG/total anti-S1-SARS-CoV-2 antibodies (r = 0.47, P < 0.0001 and r = 0.49, P < 0.0001, respectively). IgG and total Ig could predict a neutralization titer of ≥ 1:160 at S/CO >4.44 and >65 with AUC 0.69 and 0.67, respectively.

Conclusion: Asymptomatic SARS-CoV-2 infection can produce comparable antibodies response to previously symptomatic individuals, however higher neutralization activity was seen in the previously symptomatic. Anti-S1-SARS-CoV-2 IgG/total Ig antibodies showed a correlation with neutralization activity and can be used to estimate the presence of protective immunity.

Keywords: Asymptomatic; Chemiluminescence; Neutralizing antibodies; Previously symptomatic; SARS-CoV-2.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antibodies, Neutralizing
Antibodies, Viral
COVID-19* / diagnosis
Humans
Immunoassay
Immunoglobulin G
Luminescence
SARS-CoV-2*

Substances

Antibodies, Neutralizing
Antibodies, Viral
Immunoglobulin G