This is How SARS-CoV-2 Evades Vaccines

Jay Kakade
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COVID-19
Image: Pixabay



Studies have examined impacts of new SARS-CoV-2 Variants on Evading Efficiency of COVID Vaccines. This type of variants evading vaccines are termed as Variants of Concern by World Health Organization.

With the continuous evolution of SARS-CoV-2, Omicron a new variant has entered into scenario. Omicron has seen 50 mutations on spike proteins (Virus use this proteins to enter cell or a host). Cases of Omicron have found in Africa, Europe, Australia, Asia and North and South America. Cases are spreading rapidly in many countries.

While studying evolution and mutation of SARS-CoV-2 researchers found some mutations which may be effective against vaccines. Scientists mainly studied Spike Proteins also called as receptor binding domain. Virus use Spike Proteins to enter cell and thereafter it replicates causing infection.

Every time when a virus enters body cell, It is blocked by host's immune system. This pressure causes some changes in RNA strip of virus, making it immune against immune system. This increases chances of virus survival even in fully vaccinated patient too. Same is what seen in new variant Omicron.

It is mutation that allows virus to evade immune system. This is termed as Escape Mutation. Scientists observed simultaneous escape mutation leads virus to make better connection with receptors it need to infect cell.

Omicron
Illustration of Omicron spike protein (red) with mutation site in yellow. (Juan Gaertner/Getty Images)


Use of Pseudo Types

Researchers studied this phenomena by using pseudo types combining with Spike Proteins. This pseudo types are very much similar like virus but non-infectious and harmless. This pseudo type contains seven escape mutations enough for neutralizing vaccine. Earlier researchers thought it was hypothetical, But not after the emergence of Omicron variant.

While studying pseudo-types, Scientists were able to observe how escape mutation evaded antibodies. Some escape mutations allowed spike proteins to penetrate host cell. Here scientists found a antibody which can neutralize all variants of virus. But virus can evade it too If it developed spike proteins with sugar molecules, Which binds antibodies with virus.
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