Mutant N440K 10 Times More Infectious Than Parent Strain
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Even as scientists are busy decoding the potential threat of the double mutant (B.1.617), a team of researchers from Hyderabad and Ghaziabad has found that the mutant N440K of the novel coronavirus is 10 to 1,000 times more infectious than certain strains now in circulation. This mutant appears to be fuelling the second wave of Covid-19 in certain pockets of India.

The study reveals that the N440K variant produced 10 times higher infectious viral titres than a prevalent A2a strain and over 1,000-fold higher titres than a much less prevalent A3i strain prototype in Caco2 (epithelial) cells. As many as 1,555 entries with N440K substitution could be identified from across the world. Interestingly, India contributed the largest proportion of N440K variants at 33 percent followed by the US and Germany, the researchers said.

The proportion of the N440K variant in India has increased from 4.9 percent sequence earlier to 8.82 percent between January and April 24, they explained. “Our studies unambiguously demonstrate that N440K variant prototype has the capacity to generate significantly higher titres of infectious virus in shorter duration and suggest that this feature could promote its faster spread among certain populations,” the study, said.

According to the researchers, the N440K variant belongs to the lineage of the A2a strain. “Data suggests that the proportion of N440K variant has been increasing gradually and suggesting its improved replicative fitness or increased infectivity,” they said.

Stating that the N440K mutation has been reported in several viral sequences across India, the team said: “Based on our results, we predict that the higher infectious titres achieved by N440K variant could possibly lead to its higher rate of transmission.” The researchers, however, added that the availability of more sequencing data in the immediate future would help understand the potential spread of this variant in more detail.

The study pointed out that recent data indicate the prevalence of variants with N440K spike substitution in several parts of India, which is under the second wave of the pandemic. It confirmed the increased potency of the N440K variant.

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