ELISA test to detect Coronavirus anti-bodiesDate: 11 May 2020 Tags: Miscellaneous
The National Institute of Virology (NIV) has developed an immunological assay, Enzyme-linked Immunosorbent Assay (ELISA), to detect antibodies that the body develops in response to infection by the SARS-CoV-2 novel coronavirus.
ELISA is routinely used for detecting HIV infection. The test will detect IgG antibodies present in blood samples.
This kit was validated at two sites in Mumbai and has high sensitivity and accuracy. Besides, it has the advantage of testing 90 samples together in a single run of 2.5 hours.
This is the first time India has developed an indigenous ELISA test for coronavirus. While ELISA tests for coronavirus are already available in other countries, procuring them in large numbers may be a challenge, particularly during a pandemic. In contrast, availability will be a non-issue when a locally developed test is manufactured in India.
The ELISA test developed by NIV gains significance as the rapid antibody tests imported from China were found to be unreliable and hence States were instructed not to use them for detecting previous coronavirus infection.
Since the ELISA test is based on detection of antibodies, it can only help in knowing if the person has been previously infected by coronavirus.
Since it detects antibodies, even people who have remained symptom-free (asymptomatic) during the entire course of the infection will test positive.
While the RT-PCR, which detects the RNA of the coronavirus, enables detection of current infection, it will not be useful if the testing is carried out days after the infection clears as the virus will no longer be present.
However, antibodies developed in response to the coronavirus infection will be present in the blood for a longer duration and hence the ELISA test can help detect past infection. The maximum time the antibodies will be present in the body is not known for coronavirus.