Strain spotting

The UK variant of Covid-19 may not be a serious threat, but the mutations necessitate enhanced genomic surveillance

- NAMITA KOHLI

THE COVID-19 story had begun to appear hopeful with early approval for at least two vaccines and over 4.4 million doses administered already. But on December 14, scientists in the UK sounded the alarm once again. SARS-CoV-2, they said, had acquired several mutations, giving it the ability to spread faster. First spotted in September, mutations in SARS-CoV-2 were seen in two-thirds of the cases in London by mid-December. Since then, many countries reported the presence of the new variant, indicating its rapid spread. On December 29, India joined the list—of the 114 UK returnees who tested positive, six had the new variant.

The new strain has 17 mutations that are significant, to the extent that they have rendered the virus more contagious (by up to 70 per cent), reports from the UK suggest. No effect on the severity of disease, change in symptoms or mortality has been found, yet. But scientists say that early studies show it is better at entering human cells and infecting them. “Three main mutations are important. The N501Y mutation seems to be responsible for the efficient binding of the receptor-binding domain of SARS-CoV2 spike protein with the ACE2 receptor,” said Dr Sunit Singh, professor, Banaras Hindu University. The ACE2 receptor is a protein on the surface of many cell types and provides the gateway for SARS-CoV2 to infect the cell.

“The second mutation (amino acid deletions) might be responsible for helping the virus evade the human immune system,” said Singh. “The third mutation, P681H, might be helpful in the cellular entry of this virus after infection.”