In a pandemic that has so far affected 635 million people and killed 6.6 million people, the origin of the pathogen Covid 19 remains of great importance. But the science is still in the dark: According to the latest research results, SARS-CoV-2 and bat viruses may have had a common ancestor just a few years ago. But the details of the development remain obscure, reports the British scientific journal Nature.
Recently (November 8) the 7th World One Health Congress took place in Singapore. The genesis of the pandemic was also discussed there. Since at least the early 2020s, many teams of scientists – a hot spot are laboratories in Southeast Asia – have been sequencing the genetic material of an increasing number of coronaviruses from different mammalian species. In addition, there is frozen tissue material with coronaviruses from recent years or decades. This should ultimately result in a family tree from which the origin of SARS-CoV-2 can be unequivocally deduced and which would also counter the recurring and as yet in no way verifiable speculations about SARS-CoV-2 “escape” from a laboratory. end
So far, science has already collected many puzzle pieces about the origin of the pathogen Covid 19, but a definitive solution is still missing. Australian “Nature” author Smriti Malapaty, referring to the research results presented at the Singapore conference: “To date, more than a dozen viruses closely related to SARS-CoV-2 have been isolated from bats and pangolins.” SARS-CoV-2 often compared whole genomes, each about 30,000 base pairs long.
Bat virus and Corona had common ancestors
Using this method, the scientists identified its closest relatives, a bat virus from Laos called BANAL-52 and a bat virus from Yunnan in southern China called RaTG13. The genome of BANAL-52 is 96.8 percent identical to SARS-CoV-2, that of RATG13 is 96.1 percent. The three to four percent difference suggests that these two viruses shared a common ancestor 40 to 70 years ago.
However, comparing the composition of entire genomes has one drawback: it does not take into account the rapid recombination with the exchange of individual genome sections between different virus types. So evolutionary virologist Spyros Lytras and his team from the University of Glasgow analyzed 18 bat and pangolin viruses closely related to SARS-CoV-2 in 27 parts each. These genome fragments were each several hundred to several hundred thousand base pairs long. Each segment would have a different evolutionary history, Lytras pointed out.
“This analysis shows that some segments with SARS-CoV-2 had a common ancestor a few years ago. Most of these fragments pointed to a common origin around 2007. But a small fragment of the genome, just 250 base pairs long, could point to a common ancestor in 2016, and another fragment of 550 nucleotides to one in 2015. That would take three to four years for SARS-CoV-2 to show up in humans. popped up,” wrote the author of Nature. Lytras would have emphasized that mainly due to the migration of bats – with their harmless viruses – an emergence of the Covid 19 pathogens in southern China and Southeast Asia can be assumed.
Recombinations between viruses complicate research
However, whether the direct origin of SARS-CoV-2 will ever be determined remains controversial among virologists concerned with pathogen evolution. The recombination between viruses that constantly takes place in host organisms very quickly clouds the picture. Edward Holmes, virologist at the University of Sydney: “The chances of that happening are almost zero. This steamer has departed.”
Source: Krone
I’m Wayne Wickman, a professional journalist and author for Today Times Live. My specialty is covering global news and current events, offering readers a unique perspective on the world’s most pressing issues. I’m passionate about storytelling and helping people stay informed on the goings-on of our planet.
