Coronavirus variant causes rocketing case rates
January 6, 2021 -
All viruses naturally mutate when they replicate, changing the genome -- the genetic blueprint -- enabling a virus to function. The British coronavirus variant B117 has now spread to more than 30 countries, including the U.S., France and India.
Rising case rates from the new virus strain mean one person in every 50 in England now has Covid-19, while in London one in 30 is infected, survey results from the UK Office for National Statistics (ONS) show.
The B117 variant of the coronavirus appears to be more contagious than other variants. According to tests conducted at the Birmingham Turnkey Lab, around 35% of patients infected by the B117 form had very high levels of the virus in their samples, compared to 10% of patients without the variant. The studies of the new variant prompted Prime Minister Boris Johnson to announce a third national lockdown.
The variant came to the attention of researchers in December in parts of southern England. When researchers took a close look at its genome, they discovered that of 17 amino acid mutations, eight affect the spike protein of the virus.
Most significantly, mutations had occurred on the genome receptor binding domain known as N501Y, situated on the spike glycoprotein which the virus employs to hijack human cells.
The spike protein binds to ACE2 receptors (Angiotensin-converting enzyme 2) on the host cell -- the entry point into a human cell for a virus to replicate.
In the N501Y mutation, researchers found the amino acid tyrosine had replaced the amino acid asparagine. The change increases B117’s access to the ACE2 receptor, making children more susceptible to the virus. Usually, children are less likely than teenagers or adults to get infected or pass on the virus.
Professor Neil Ferguson, an epidemiologist at Imperial College London, estimates that the variant has an increased transmission rate of 50 to 70 per cent compared with other variants in the UK.