Double and triple mutants of coronavirus one and the same; vaccines effective on it: Scientist

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The double and triple mutant strains detected in India are one and the same variant of the coronavirus, and the available vaccines are effective on it, National Institute of Biomedical Genomics Director Soumitra Das said on Friday. Speaking at a webinar on 'Genome Sequencing of SARS-CoV-19', Das said double mutant and triple mutant terms are "colloquial" and both refer to the same variant -- B.1.617 variant of the coronavirus.

"Double and triple mutants are one and the same. Double and triple mutants are over-lapping terms and have been used differentially in different context," he said.

The National Institute of Biomedical Genomics in Kalyani is an institute under the Department of Biotechnology and is one of the 10 laboratories across the country involved in the genome sequencing of the coronavirus.

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In fact, these variants harbour 15 lineage defining mutations. B.1.617, initially termed double mutant, has three new spike protein mutations, he said.

Two mutations -- E484Q and L452R -- are in the area important for antibody-based neutralisation.

"Initially we were signifying two mutations which are important for escape (the vaccine escape and antibody escape). That is why it is called the double mutant,” he said.

But this mutant or variant also has another mutation which is called P681R. That mutation allows the virus to enter the cell little better.

"If you now take both the context, the escape variant, plus the entry or infectivity, then it is a triple mutant, but if you only consider about a new variant or escape variant, then it is a double mutant. If you take double and triple mutants, (they) are over-lapping and are one and the same,” Das added.

There is apprehension among experts that the new variant could also increase infection rates and easily surpass immune defences.

“Variants found in India are not really escaping our vaccinated sera,” Das said, suggesting that the available vaccines are effective on them.

He said that to avoid confusion, a uniform nomenclature for the variants should be used as recommended by the WHO.

Noted virologist Shaheed Jameel referred to the study done by Cellular and Molecular Biology, another lab involved in the sequencing of the coronavirus genomes, saying preliminary results have shown that Covishield vaccine protects against the B.1.617 variant. 

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