Development of indigenous IgG ELISA for the detection of anti-SARS-CoV-2 IgG

Abstract

Background & objectives: Since the beginning of the year 2020, the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacted humankind adversely in almost all spheres of life. The virus belongs to the genus Betacoronavirus of the family Coronaviridae . SARS-CoV-2 causes the disease known as coronavirus disease 2019 (COVID-19) with mild-to-severe respiratory illness. The currently available diagnostic tools for the diagnosis of COVID-19 are mainly based on molecular assays. Real-time reverse transcription-polymerase chain reaction is the only diagnostic method currently recommended by the World Health Organization for COVID-19. With the rapid spread of SARS-CoV-2, it is necessary to utilize other tests, which would determine the burden of the disease as well as the spread of the outbreak. Considering the need for the development of such a screening test, an attempt was made to develop and evaluate an IgG-based ELISA for COVID-19. Methods: A total of 513 blood samples (131 positive, 382 negative for SARS-CoV-2) were collected and tested by microneutralization test (MNT). Antigen stock of SARS-CoV-2 was prepared by propagating the virus in Vero CCL-81 cells. An IgG capture ELISA was developed for serological detection of anti-SARS-CoV-2 IgG in serum samples. The end point cut-off values were determined by using receiver operating characteristic (ROC) curve. Inter-assay variability was determined. Results: The developed ELISA was found to be 92.37 per cent sensitive, 97.9 per cent specific, robust and reproducible. The positive and negative predictive values were 94.44 and 98.14 per cent, respectively. Interpretation & conclusions: This indigenously developed IgG ELISA was found to be sensitive and specific for the detection of anti-SARS-CoV-2 IgG in human serum samples. This assay may be used for determining seroprevalence of SARS-CoV-2 in a population exposed to the virus.

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

“…We did try different concentrations of BPL, and chose 0.1 % as optimum for inactivation. Based on screening of 200 healthy donor sera/plasma collected before SARS-CoV-2 emergence, specificity of our ELISA was 97 %, and thus comparable with the several recombinant protein based ELISAs (95.2–100 %) ( Tahamtan and Ardebili, 2020 ; Van Elslande et al, 2020 ; Kohmer et al, 2020a , b ; Zhao et al, 2020a ; 2020b ; Perera et al, 2020 ; Serrano et al, 2020 ) and a gamma irradiated whole virus based test (97.9 %) ( Sapkal et al, 2020 ) reported so far. Importantly, the performance of our ELISA was at par with a US-FDA approved, widely-used commercial test (Euroimmun ELISA) ( Fig.…”

“…Clearly, BPL-inactivated virus-based ELISA was able to detect IgG early during the disease phase. The only other study employing whole virus (gamma irradiated) based IgG ELISA used samples collected after the second week of disease onset, hence data regarding the performance of this ELISA in early disease phase is unavailable ( Sapkal et al, 2020 ). We would like to point out here that use of different recombinant proteins such as NP, RBD, S1 and whole S led to variable IgG detection rates during the early disease phase.…”

Assessing seropositivity for IgG antibodies against SARS-CoV-2 in Ahmedabad city of India: a cross-sectional study

“…As per the validation reports, the kits have a sensitivity of 92.37% and a specificity of 97.9%. 12 So, with very high level of sensitivity and specificity it may be noted that the results received through this testing kit are highly reliable and the kit is permitted for use in serosurveillance of SARS-CoV-2. The manufacturer reported no cross-reactivity with other viruses in the serum from real-time RTqPCR confirmed patients of various other infections.…”

SARS-CoV, MERS-CoV and SARS-CoV-2: A Diagnostic Challenge

“…On the other hand, numerous legal and regulatory necessities have been implemented for a commercial organization to assess and equip itself to adapt to this situation. In certain countries, any individual susceptible of transmitting viral infection of any life-threatening disease is liable to fines or even 24 months imprisonment at times [120] , [121] , [122] , [123] , [124] .…”