Unique A3i Strain in 41% Covid-19 Infections In India-CSIR

Amid the rising number of coronavirus cases in India, scientists have found a distinct cluster of covid population prevalent in India called Clade A3i, that comprises 41% of all SARS-CoV-2 genomes of Indian samples and 3.5% of global genomes submitted in public domain. The cluster has been uncharacterized so far and is believed to have originated from an outbreak in February and spread across India.

The causative virus behind the epidemic,  SARS-CoV-2, is a member of the genus betacoronavirus. It has differentiated into at least 10 clades globally and is continuously evolving.

About A3i:

Besides, other things, this particular trait could potentially make the virus weaker, one of the scientists involved in the study said.

The researchers, who sequenced 64 genomes (the complete set of genetic material) linked the Clade I/A3i cluster to the predominant SARS-CoV-2 strain circulating in Tamil Nadu, Telangana, Maharashtra, and Delhi.

The A3i clade seems to be the clade responsible for the initial outbreak across the country.While Clade A2a is seen around the world, Clade A3i is found mostly in India. Singapore is the only other country where 8% presence of such a clade has been

According to ICMR, there has been very little mutation in the important areas of the viral genome.It mutates slower compared to the other clade (A2a) which is prevalent in India, which is often disadvantageous for the virus.The discovery by CSIR scientists is set to expand the understanding of scores of researchers who are trying to figure out a way to fight the virus with  drugs and vaccines.

The most dominant coronavirus clade in India is the A2a, and of 213 genomes analysed by the group, 62% of them were A2a. The newly identified type, that the scientists have christened A3i, comprised 41% of those analysed.

A2a Strain:

As the virus was carried by travellers from China, the O-type of the coronavirus initially spread to other global regions. Then, the virus evolved in China, as well as outside the country. In each geographical region, many different types of SARS-CoV-2 came up, and began spreading rapidly during January and February this year. However, in most geographical regions, only one type (A2a) of SARS-CoV-2 started to overtake other types.

Researchers have found that because the A2a type is so efficient in transmitting, COVID-19 has become so prevalent and widespread.

According to the researchers, the A2a type has acquired a change in its RNA sequence that alters a component (an amino acid alteration from aspartic acid to glycine) of the spike protein, at position number 614, of the coronavirus.

How Covid-19 Virus attacks the Human Body?

  1. When the coronavirus infects a person, it enters the lungs and makes millions of copies of itself there.
  2. As a result of the huge load of the virus in the lungs, the infected person falls ill, has enormous breathing difficulty and sometimes dies.
  3. The spike protein plays a major role in the coronavirus infecting a human by entering lungs.
  4. To infect, the coronavirus has to first anchor itself to a lung cell. Human lung cells produce a protein called ACE2 on their surface. The spike protein of the coronavirus first clings on (binds) to this surface protein ACE2.
  5. Then another protein takes action and promotes the entry of the virus into the lung cell.
  6. The more efficiently a type of virus can bind and enter, the more successful it will be to propagate itself. The A2a type of the coronavirus has gained this efficiency because of the amino acid change to glycine from aspartic acid. All other types of SARS-CoV-2 possess aspartic acid. The change to glycine enables the A2a type of the coronavirus to enter lung cells in larger numbers

Sources:The Hindu,The Indian Express

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