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. 2020 May;151(5):444-449.
doi: 10.4103/ijmr.IJMR_2232_20.

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

Gajanan Sapkal  1 , Anita Shete-Aich  2 , Rajlaxmi Jain  2 , Pragya D Yadav  2 , Prasad Sarkale  2 , Rajen Lakra  2 , Srikant Baradkar  2 , Gururaj Rao Deshpande  1 , Deepak Mali  2 , Bipin N Tilekar  1 , Triparna Majumdar  2 , Himanshu Kaushal  3 , Yogesh Gurav  4 , Nivedita Gupta  5 , Sreelekshmy Mohandas  2 , Ketki Deshpande  1 , Ojas Kaduskar  1 , Malvika Salve  2 , Savita Patil  2 , Shivshankar Gaikwad  1 , A P Sugunan  6 , M Ashok  7 , Sidhartha Giri  5 , Jayanthi Shastri  8 , Priya Abraham  9 , Raman R Gangakhedkar  5 ; $COVID Support Team: Pawar S., Patshute S., Salve V., Natarajan V., Marwah V., Malhotra B., Jain A., Sathe P., More R., Khedekar R., Suryawanshi D., Kalele K., Kumar A., Upadhyaya C.P., Waghmare A., Gawande P., Gopale S., Acharya M., Holeppanavar M., Thorat S., Chopade G., Vidhate S., Khutwad K., Phagiwala D., Bhanarkar S., Rakhe A., Salvi V., Dhaigude S., Ciyona
Affiliations

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

Gajanan Sapkal et al. Indian J Med Res. 2020 May.

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.

Keywords: COVID-19 - diagnosis - ELISA - human - IgG antibodies - microneutralization test - SARS-CoV-2 - standardization.

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Conflict of interest statement

None

Figures

Fig. 1
Fig. 1
Receiver operating characteristic (ROC) analysis showing sensitivity versus specificity for discrimination of positive and negative serum samples, which were derived for in-house IgG ELISA compared to microneutralization test results (ROC area under the curve: 0.986).
Fig. 2
Fig. 2
Inter-laboratory correlation analysis: A panel of 150 serum samples tested at two external laboratories and compared with the ICMR-National Institute of Virology reference laboratory indicated a positive correlation between the reference laboratory and the other laboratories.
Fig. 3
Fig. 3
Correlation analysis of SARS-CoV-2 antibody titre of microneutralization test (MNT) compared with optical densities of the in-house SARS-CoV-2 IgG ELISA (r=0.7836, P<0.001).
See this image and copyright information in PMC

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