COVID KAVACH ELISA – Indigenous IgG Elisa Antibody Test

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TOPIC: General Studies 2

• Global Pandemic – COVID-19

General Studies 3:

• New technological development to fight COVID-19

In News: The Centre announced that an IgG ELISA test for detection of antibodies to Covid-19 had been developed, and released a document outlining details of surveillance to be carried out in all districts to check for the prevalence of infection using the same.

Indian Council of Medical Research (ICMR)-National Institute of Virology (NIV) at Pune has developed the indigenous IgG ELISA (enzyme-linked immunosorbent assay test “COVID KAVACH ELISA” for antibody detection for COVID-19. This robust test will play a critical role in surveillance of proportion of population exposed to Covid-19.

What is IgG ELISA?

Pune-based National Institute of Virology has developed an immunological assay — enzyme-linked immunosorbent assay (ELISA) — that can detect antibodies that are developed in response to the coronavirus infection. This is a first test of the kind to be developed in India and it will play a critical role in surveillance of proportion of the population exposed to the virus.

ELISA-based tests are blood-based tests, which have high sensitivity and specificity. The sensitivity of a test refers to the percentage of results that will correctly find out the presence of infection in a person and specificity refers to the percentage of results that will correctly find out whether or not a person is infected. 

It has a sensitivity of 92% and its specificity is 97%.

What is the mechanism involved?

• The test involves drawing the blood of the person. 
• The sample is then placed inside the small wells of an ELISA plate. These plates are coated with the antigen or the inactivated form of the virus. 
• If the blood contains antibodies, it binds to the antigen and a substrate solution is added to the well. The reaction usually produces a colour change, thus detecting antibodies. 
• ELISA tests can be done manually or in a semi-automatic and automatic way.

What is IgG in the Indigenous IgG Elisa Antibody Test?

It is an IgG Elisa-based test which means that the test will be done to detect the Immunoglobulin G (IgG) antibody.

Antibody is a protein produced by the immune system in response to invading organisms such as bacteria and viruses. Antibodies are able to specifically recognize foreign invaders in the body, coat them by binding to them and then allow the immune cells of the body to clear them from the blood or mucous membranes, or sites like the lung.

Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells.

The antibody test isn’t checking for the virus itself. Instead, it looks to see whether your immune system — your body’s defense against illness — has responded to the infection.

Note: 

• ELISA-based tests and point-of-care tests are not used for confirming Covid-19 infection and are only used for surveillance purpose.
• Immunoglobulin G, or IgG antibodies are more likely to show up later after you’ve recovered

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