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HOW ‘CORONA’ OF THE VIRUS CHANGES SHAPE?

Focus: GS-III Science and Technology

Introduction

  • Researchers have found that the spike protein of SARS-CoV-2 — the ‘corona’ in the coronavirus that causes Covid-19 disease — changes its form after it attaches itself to a human cell, folding in on itself and assuming a rigid hairpin shape.
  • The researchers have published their findings in the journal Science, and believe the knowledge can help in vaccine development.

What is the spike protein?

  • It is a protein that protrudes from the surface of a coronavirus, like the spikes of a crown or corona — hence the name ‘coronavirus’.
  • In the SARS-CoV-2 coronavirus, it is the spike protein that initiates the process of infection in a human cell.
  • It attaches itself to a human enzyme, called the ACE2 receptor, before going on to enter the cell and make multiple copies of itself.

What has the new research found?

  • Using the technique of Cryogenic Electron Microscopy (cryo-EM), researchers have freeze-framed the spike protein in both its shapes — before and after fusion with the cell.
  • The images show a dramatic change to the hairpin shape after the spike protein binds with the ACE2 receptor.

In what way can it protect the virus from the immune system?

  • The postfusion shape could induce antibodies that do not neutralise the virus.
  • In effect, the spikes in this form may act as decoys that distract the immune system.
  • Both the “before” and “after” forms have sugar molecules, called glycans, at evenly spaced locations on their surface, and Glycans are another feature that helps the virus avoid immune detection.

How is the knowledge about the alternative shape useful?

  • The researchers believe the findings have implications for vaccine development.
  • Many vaccines that are currently in development use the spike protein to stimulate the immune system.
  • But these may have varying mixes of the prefusion and post-fusion forms and that may limit their protective efficacy.
  • If the protein is not stable, antibodies may be induced but they will be less effective in terms of blocking the virus.

-Source: Indian Express

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September 2022
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