A new analysis of coronavirus genomes from over 15,000 Covid-19 patients from 75 countries has found that none of the new mutations appears to be transmitted at a higher rate. The study, which is published today as a pre-print and has not yet been peer-reviewed, builds on another recent, peer-reviewed study published in the journal Infection, Genetics and Evolution. The previous study characterised patterns of diversity emerging in the genome of SARS-CoV-2.
“We employed a novel technique to determine whether viruses with the new mutation are actually transmitted at a higher rate, and found that none of the candidate mutations appear to be benefiting the virus,” lead author Professor Francois Balloux (University College London Genetics Institute) said in a statement.
Coronaviruses can develop mutations in three different ways: by mistake from copying errors during viral replication; through interactions with other viruses infecting the same cell; or as a result of the immune response of the host. Most mutations are neutral, while others are advantageous or detrimental to the virus.
The research team from multiple institutions has so far identified 6,822 mutations in SARS-CoV-2 across the global dataset. Of those, the researchers honed in on 31 mutations which have occurred at least 10 times independently during the course of the pandemic.
The researchers modelled the virus’s evolutionary tree, and analysed whether a particular mutation was becoming increasingly common within a given branch of the evolutionary tree.
The researchers found no evidence that any of the common mutations are increasing the virus’s transmissibility. Instead, they found some common mutations are neutral, but most are mildly detrimental to the virus. 📣 Express Explained is now on Telegram
The mutations analysed included one in the virus spike protein called D614G, which has been widely reported as being a common mutation which may make the virus more transmissible. The researchers said the new evidence suggests this mutation is, in fact, not associated with increased transmission.
The researchers found most of the common mutations appear to have been induced by the human immune system, rather than being the result of the virus adapting to its novel human host.
Source: University College Londonx
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