New Delhi: Indigenous IgG-based ELISA kits for COVID-19 testing have been found to be sensitive and specific for the detection of coronavirus infection in human serum samples. Hence, these ELISA kits will be useful in screening healthcare workers, industry workers, and other people exposed to the virus, according to the Indian Council of Medical Research (ICMR) in its latest scientific paper.
A total of 513 blood samples (131 positives, 382 negatives for SARS-CoV-2) were collected and tested by micro-neutralization test (MNT). "The virus neutralization is regarded as the gold standard method for a serological assay. The in-house ELISA results correlated strongly with neutralization assay, indicating that the assay was sensitive and specific for the detection of anti-SARS-CoV-2 IgG," it said.
"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," stated ICMR findings.
The assay performance was not different with the use of serum or plasma. No cross-reactivity with other respiratory viruses was detected. This kit may be used to detect exposed immune-protected individuals.
This ELISA will be useful in screening healthcare workers, industry workers, etc.According to the apex medical research body, for surveillance of the emerging and re-emerging viruses, serological assays have been widely recommended.
Several IgM/IgG ELISA kits for COVID-19 are in the stage of development.However, validated and approved SARS-CoV-2 serological assays are lacking for case detection and are not included in laboratory testing guidelines for COVID-19 of the WHO.
"Due to the non-availability of an indigenous, approved and cost-effective kit, an in-house ELISA was developed and validated for the detection of anti-SARS-CoV-2 human IgG antibodies," read the paper.
The ELISA kits can be produced at lower manufacturing cost. It gives easy-to-use and affordable kits to resource-limited settings.The study concluded that this indigenous anti-SARS-CoV-2 human IgG-ELISA may be used for ascertaining the seroprevalence against SARS-CoV-2 in a population and for epidemiological studies.