Anti-SARS-CoV-2 IgG antibody response among Indian COVID-19 patients using β-propiolactone-inactivated, whole virus-based indirect ELISA

• Published in: Journal of virological methods Vol. 287; p. 113996
• Main Authors: Kulkarni, Ruta, Patil, Harshad P., Palkar, Sonali, Lalwani, Sanjay, Mishra, Akhilesh Chandra, Arankalle, Vidya
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2021
• Subjects: Antibodies, Viral - blood; Antibody; COVID-19; COVID-19 - blood; COVID-19 - diagnosis; COVID-19 - pathology; COVID-19 Serological Testing - methods; ELISA; Enzyme-Linked Immunosorbent Assay; Humans; IgG; Immunoglobulin G - blood; Inactivated virus; Propiolactone - pharmacology; SARS-CoV-2; SARS-CoV-2 - immunology; Sensitivity and Specificity; Seroepidemiologic Studies; Virus Inactivation - drug effects; COVID-19; IgG; SARS-CoV-2; Inactivated virus; Antibody; ELISA
• ISSN: 0166-0934; 1879-0984
• DOI: 10.1016/j.jviromet.2020.113996

•Development of indirect IgG ELISA using β-propiolactone-inactivated SARS-CoV-2.•Detection of anti-SARS-CoV-2 IgG during early disease phase.•Higher IgG seropositivity and OD values in COVID-19 patients with severe disease. Coronavirus disease 2019 (COVID-19) pandemic caused by infection with severe acute respiratory syndrome – coronavirus-2 (SARS-CoV-2) continues to affect many countries and large populations. Serologic assays for antibody detection aid patient diagnosis and seroepidemiologic investigations. An indirect IgG ELISA was developed indigenously using β-propiolactone (BPL) inactivated SARS-CoV-2. This assay was used for screening 200 healthy donor sera collected prior to COVID-19 emergence (2017–2019), 185 serum/plasma samples of confirmed COVID-19 patients (n = 137) and 57 samples of viral RNA positive asymptomatic contacts (n = 51). The IgG response was studied in relation to duration and severity of illness. The ELISA demonstrated 97 % specificity and IgG detection in >50 %, 80 %, 93.8 % and 100 % of the patients respectively during the first, second, third and fourth week of illness. IgG detection rate was higher in patients with severe disease (SD, 90.9 %) than those with mild disease (MD, 68.8 %) during the second week of illness (P = 0.027). IgG seropositivity among asymptomatic contacts was 64.7 %. IgG ELISA absorbance values were higher in SD than MD patients during the first 2 weeks of illness (P < 0.05). No significant difference was observed between the absorbance values of asymptomatic subjects and MD patients (P = 0.94). The BPL inactivated virus-based ELISA could detect IgG antibodies early and in a significant proportion of COVID-19 patients suggesting its potential utility as a supplement to the currently used viral RNA detection tests in patient diagnosis and contact screening algorithms.