Originally Posted by
wco81
Summary?
It is an opinion piece by a single author.
I read it and cannot find a free link, but here is the take home point....
The closest animal version of the virus remains a bat sample collected by scientists in 2013 a thousand miles away in Yunnan. Details of where and how that sample was collected have been sketchy, but a new paper by two scientists from the Agharkar Research Institute in Pune, India, show that it is the same as a published sample with a different name that was collected from an abandoned mineshaft in southern Yunnan in 2013, following an outbreak of pneumonia-like illness that killed three miners there the year before. But that virus cannot be the immediate source of Covid-19. Part of one of its key genes, coding for the “spike” protein that allows the virus to lock onto human cells, is distinct from the version that is causing the pandemic. In the human virus, this part of the gene, called the “receptor binding motif,” more closely resembles the virus found in smuggled pangolins, though the rest of the pangolin virus is less similar. Compared with the bat and pangolin viruses, the one now infecting human beings also has an extra 12-letter nucleotide sequence, called a “furin cleavage site,” in the spike protein gene; this greatly enhances the virus’s ability to get into and out of different types of human cells. Kristian Andersen of the Scripps Institute in La Jolla, Calif., and colleagues argue that this might have arisen by mutation during “a period of unrecognized transmission in humans” after the original transmission from an animal.
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So what did happen? At present, the evidence is pointing tentatively to a chain of person-to-person infections occurring somewhere outside a city before somebody brought the virus to Wuhan, where the market acted as an amplifier. The first case could have been a rural farmer or possibly a bat researcher collecting samples for virologists. Or it is possible that another animal was involved in some way, with the virus bouncing between a farmer and his animals, or a wildlife smuggler and his poor pangolins.