Coronavirus | National Institute of Virology develops ELISA test 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, an official source told The Hindu. The test will detect IgG antibodies present in blood samples. ELISA is routinely used for detecting HIV infection.

“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,” Union Health Minister Dr. Harsh Vardhan tweeted. He also tweeted to say that NIV had transferred the technology to Zydus Cadila for mass-scale production. The Drug Controller General had granted commercial production and marketing permission to Zydus Cadila, he added.

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 company that has been licensed to manufacture the ELISA test will have about a month to make the tests available as collection of 30,000 blood samples taken randomly from people in the general population in the 75 hotspot districts will begin by the third week of May.

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Dr. Balram Bhargava, Director-General of the Indian Council of Medical Research could not be reached for comments.

Of significance

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.

The ELISA test will be used to screen 30,000 samples from 75 hotspot districts to understand the extent of spread of the virus in the community. India has thus far maintained that there is no community transmission despite there being over 63,500 cases so far from across the country.

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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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Printable version | Oct 16, 2021 3:10:57 AM |

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