Coronavirus |National Institute of Virology Pune develops ELISA test Kit to detect antibodies.
The Pune-based 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, The test will detect IgG antibodies present in blood samples. ELISA is routinely used for detecting HIV infection.
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. However, according to the Centers for Disease Control and Prevention (CDC), it takes one-three weeks for the antibodies to develop in response to infection. So, if a person who has been recently infected by the virus is tested during the window period (the time taken to develop antibodies) the result will turn out to be negative. But a repeat test after a couple of weeks will indicate the true infection status.
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.
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