Early detection of neutralizing antibodies against SARS-CoV-2 in COVID-19 patients in Thailand

• Published in: PloS one Vol. 16; no. 2; p. e0246864
• Main Authors: Putcharoen, Opass, Wacharapluesadee, Supaporn, Chia, Wan Ni, Paitoonpong, Leilani, Tan, Chee Wah, Suwanpimolkul, Gompol, Jantarabenjakul, Watsamon, Ruchisrisarod, Chanida, Wanthong, Phanni, Sophonphan, Jiratchaya, Chariyavilaskul, Pajaree, Wang, Lin-Fa, Hemachudha, Thiravat
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12.02.2021; Public Library of Science (PLoS)
• Subjects: Adult; Antibodies; Antibodies, Neutralizing - analysis; Antibodies, Neutralizing - isolation & purification; Antibodies, Viral - isolation & purification; Asymptomatic infection; Biology and life sciences; Contact tracing; Coronaviruses; Cough; COVID-19; COVID-19 - diagnosis; COVID-19 - immunology; COVID-19 Nucleic Acid Testing; COVID-19 Serological Testing - methods; Editing; Electronic mail; Female; Fever; HIV; Hospitals; Human immunodeficiency virus; Humans; Humoral immunity; Immune response; Immune system; Infections; Infectious diseases; Male; Measurement; Medicine; Medicine and health sciences; Metropolitan areas; Middle Aged; Myalgia; Neutralization Tests - methods; Nose; Olfaction; Pandemics; Patients; Pediatrics; Pharmacogenomics; Pharmacokinetics; Pharmacology; Pneumonia; Polymerase chain reaction; Public health; Research and Analysis Methods; SARS-CoV-2 - physiology; Sensitivity and Specificity; Serologic Tests; Serology; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Signs and symptoms; Smell; Spike Glycoprotein, Coronavirus - chemistry; Thailand; Training; Vaccines; Viral antibodies; Viral diseases; Viral infections; Viruses; Young Adult; Zoonoses; Thailand; Singapore; United States > US; Bangkok Thailand
• DOI: 10.1371/journal.pone.0246864
• ISSN: 1932-6203

The presence of neutralizing antibodies (NAbs) is an indicator of protective immunity for most viral infections. A newly developed surrogate viral neutralization assay (sVNT) offers the ability to detect total receptor binding domain-targeting NAbs in an isotype-independent manner, increasing the test sensitivity. Thus, specimens with low IgM/ IgG antibody levels showed strong neutralization activity in sVNT. This study aimed to measure the %inhibition of NAbs measured by sVNT in PCR-confirmed COVID-19 patients. The sensitivity of sVNT for the diagnosis of SARS-CoV-2 infection and its kinetics were determined. Ninety-seven patients with PCR-confirmed SARS-CoV-2 infection were included in this study. Majority of the patients were 21-40 years old (67%) and 63% had mild symptoms. The sensitivity of sVNT for the diagnosis of SARS-CoV-2 infection was 99% (95% confidence interval (CI) 94.4-100%) and the specificity was 100% (95% CI 98.3-100%). The negative predictive value of sVNT from the samples collected before and after 7 days of symptom onset was 99.5% (95% CI 97.4-100%) and 100% (95% CI 93.8-100%), respectively. The level of inhibition at days 8-14 were significantly higher than days 0-7 (p<0.001). The median %inhibition values by severity of COVID-19 symptoms were 79.9% (interquartile range (IQR) 49.7-91.8%); 89.0% (IQR 71.2-92.4%); and 86.6% (IQR 69.5-92.8%), for mild, moderate and severe/critical symptoms respectively. The median level of sVNT %inhibition of severe was significantly higher than the mild group (p = 0.05). The sVNT is a practical and robust serological test for SARS-CoV-2 infection and does not require specialized biosafety containment. It can be used clinically to aid diagnosis in both early and late infection especially in cases when the real-time RT-PCR results in weakly negative or weakly positive, and to determine the protective immune response from SARS-CoV-2 infection in patients.