A recent observation made by the Indian SARS-CoV-2 Consortium on Genomics (INSACOG) has found that the second Covid wave in the country during April and May directly coincided with the rise in the number of infections caused by the B.1.617 variant of the SARS-CoV-2.
INSACOG is a grouping of 10 national laboratories.
The variant contains mutations from two separate virus variants, namely E484Q and L452R. The strain, which was first only found in Maharashtra, Punjab, and Delhi has now been reported in West Bengal, Andhra Pradesh, Gujarat and Telangana as well.
According to health experts, the L452R variant was first found in the US, whereas the E484Q variant is indigenous.
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The constituent mutated strains E484Q and L452R were found to be highly infective with high transmission rates. Therefore, they make B.1.617 more infectious and deadly.
"The current surge in cases seen over the last two months in some states shows a correlation with the rise in the B.1.617 lineage of SARS CoV-2," the Indian SARS-CoV-2 Consortium on Genomics (INSACOG) said.
The B.1.617 lineage has further evolved into three sub lineages -- B.1.617.1, B.1.617.2 and B.1.617.3. Early data shows B.1.617.2, dubbed Delta by the WHO, has higher transmission advantages over the other two sub-lineages.
B.1.617, initially termed a double mutant, has three new spike protein mutations. Two mutations -- E484Q and L452R -- are in the area important for antibody-based neutralisation.
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The third mutation -- P681R in B.1.617 -- along with the reversion of E484Q allows its sub-lineage to be more infectious.
It was found in high levels in genomes sequenced in Maharashtra (2,077), West Bengal (630), Delhi (1,458), Karnataka (225) as of May 28, and accumulates new mutations in spike and other genes, the INSACOG found in the genomes sequenced as of May 28.
The World Health Organisation (WHO) has termed it a 'Variant of Concern'.
B.1.617.1 and B.1.617.3 sub-lineages have two receptor binding domain mutations --- L452R and E484Q. The former has seven spike mutations, while the latter has seven to eight.
In the case of B.1.617.2, it has nine to 10 spike mutations and two receptor binding domain mutations --- L452R and T478K. B.1.6171.1 and B.1.617.2 have higher transmission rate and reduced susceptibility to neutralisation antibodies.
In the case of all the three sub-lineages, it has the potential to reduced antibody efficacy and potential reduced neutralisation by vaccine sera, which, however, remains to be established.
B.1.1.7, also known as the Alpha variant, has 50 per cent increased transmission. It also has increased severity.
The INSACOG is a grouping of 10 national laboratories that was established by the Ministry of Health and Family Welfare on December 25 last year.
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It has been carrying out genomic sequencing and analysis of Covid-19 viruses and correlating epidemiological trends with genomic variants.
Genomic variants of various viruses are a natural phenomenon and are found in almost all countries.
(With PTI inputs)
