Features of the Development and Application of Diagnostic ELISA Systems for the Detection of Antibodies to the SARS-CoV-2 Coronavirus in Clinical Practice

Abstract

Introduction. The new coronavirus infection, COVID-19, caused by SARS-CoV-2 has reached the scale of a pandemic. Detection of antibodies to SARS-CoV-2 is an aid in the diagnosis of COVID-19, and is also used to assess the immune response to the infection. Since COVID-19 is a new disease, seroconversions and kinetics of antibody to SARS-CoV-2 are not well understood.
 The aim of the study is to evaluate seroconversions and kinetics of antibodies to SARS-CoV-2 (IgA, IgM, IgG and total) in real clinical practice using test systems of national production.
 Materials and methods. 327 blood samples obtained from patients with a confirmed diagnosis of COVID-19 with active infection, convalescents and healthy donors were analyzed. Detection of antibodies to SARS-CoV-2 was carried out by enzyme immunoassay method using registered test systems Antigma-A, Antigma-G, Antigma-Screen and an unregistered test system for the detection of class M immunoglobulins.
 Results. When testing for total antibodies, 50.0% of samples were positive on days 1-7; 89.4% on days 8-14; 96.2% on days 15-45; and 93.3% after the 46th day after disease onset. The earliest seroconversions occurred on the 3rd day; antibodies were detected up to 81 days after the disease onset.
 Conclusions. The frequency of detecting seroconversions when using test systems of the Antigma series in real clinical practice is comparable to the data published in the world scientific literature and is high enough to use these test systems in the COVID-19 diagnostics.