Reply to thread

Message: [QUOTE="pj, post: 3479265, member: 2524"] It's a good talk. Some key points: - The slide at 37:00 shows the degrees of genetic similarity you'd expect for zoonotic transmission. The most likely precursor to the 2002 SARS-CoV was WIV-16 in bats with 98% sequence similarity and a civet strain with 99.5% sequence similarity enabling the jump to virulence in humans. Still, even with a close host, it wasn't very infectious in humans and died out quickly. This compares to SARS-CoV-2 having less than 96% sequence similarity to the nearest known animal virus (a virus which is incapable of infecting humans), and no animal in which it has been proven to replicate in. - The slide at 42:56 presents my point about why SARS-CoV-2 is unlikely to be zoonotic - it is incompatible with what he calls the "Classic Model" of zoonotic transmission in which mutations are needed in the new host to drive virulence. He hypotheses a new model in which bats can now serve as a "Zoonotic Virus Pool" in which they incubate many variations of virus some of which may be able to jump to humans and be infectious immediately. Of course this is the only model which could possibly account for a zoonotic origin of SARS-CoV-2, that's why he proposes it, but as of now there is no evidence for it - SARS-CoV-2 has not been found in bats, nor any virus like it. - The slide at 50:37 has the phylogenetics, presenting my point about the huge genetic distance from all previously known coronaviruses. He mentions the one reported bat sequence, RaTG13, with 96% nucleotide similarity / 1200 nt different ("quite different" as he says at 51:12). Again, see the recent Nature article I cited previously summarizing the search for a zoonotic reservoir. [URL='https://www.nature.com/articles/d41586-020-00548-w']Mystery deepens over animal source of coronavirus[/URL]. The RaTG13 bat virus cannot infect humans, so it is not transmissible. In pangolins the closest virus found has only 92.4% similarity. So it's a fine talk, but the zoonotic hypothesis is the only origin hypothesis he discusses and he doesn't present any evidence in support of it. So, fine talk, but he doesn't refute any assertion I've made, in fact the evidence he presents supports my assertions. [/QUOTE]

Verification: First name of men's bb coach