by Smriti Mallapaty
November 10, 2022
Introduction:
Read more here: https://www.nature.com/articles/d41586-022-03611-w(Nature) The virus that causes COVID-19 probably shared an ancestor with bat coronaviruses more recently than scientists had thought. But finding the direct ancestor of SARS-CoV-2 is very unlikely, say researchers.
The full genomes of SARS-CoV-2 and several closely related bat coronaviruses suggest they shared a common ancestor several decades ago. But the viruses are known to swap chunks of RNA with each other, a process called recombination, so each section has its own evolutionary history. In the latest analysis, presented at the 7th World One Health Congress in Singapore on 8 November, scientists compared fragments of coronavirus genomes. The analysis suggests that some sections of bat coronaviruses and SARS-CoV-2 shared a common ancestor as recently as 2016 — just three years before the virus emerged in people in late 2019. The work has not been peer reviewed.
The finding narrows the time between the ancestor of SARS-CoV-2 originating in bats and the virus jumping to people, say researchers. However, it doesn’t explain how SARS-CoV-2’s closest ancestor made this jump — an enduring mystery of the pandemic, which many scientists agree probably involved an intermediary animal.
Direct ancestor
The study highlights how difficult it will be to find the direct ancestor of SARS-CoV-2 in bats, given how often coronaviruses recombine and how much time has passed. The chances of finding a direct ancestor “are almost nil”, says Edward Holmes, an evolutionary virologist at the University of Sydney in Australia. “That ship has sailed.”