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Message: [QUOTE="JustbrewitMan, post: 3479468, member: 7806"] You're overlooking the most important thing to determining the potential ability of any pathogen (including viruses) to cause infection and/or disease across multiple species: [LIST] [*]It's not the [B][I]overall [/I][/B]genetic similarity that is most important (though usually it ends up being quite high due to the way genetic replication works), its the [B][I]genetic similarity of the regions of the genome [/I][/B](and the proteins, etc. produced by those regions) [B][I]that are most important for cross-species infectivity[/I][/B]. And the SARS-CoV-2 virus is [B]HIGHLY [/B]similar in the most important regions of the binding receptor that is needed to cause cell infectivity in bats, humans, and other tested mammals (the ACE2 receptor). [/LIST] You're not interpreting this info correctly. The "Classic model" requires [B][I]multiple random rare [/I][/B]mutational events to explain cross-species infections. As implied, this doesn't mean it's NOT POSSIBLE, but based on the available evidence at the time of the classic model development, it fit the data best to explain what people thought happened (bat to civet to human). A good analogy would be hitting the lottery twice. Has it happened? Yes. Very rarely! But of the people that have hit the lottery, how many have hit the lottery once vs. twice? Probably about 99.99% versus 0.01% (and it's probably even lower than that...). And how many people have played the lottery that haven't won big (99.99%+, most likely). Rare events can indeed happen, but when they appear to start happening more frequently than before, perhaps something has changed in that rare-event system. You should go back and double-check to see if something is different. His new proposed model makes[B][I] much more sense[/I][/B] given the emergence of all the newer research data that: [LIST] [*]We now know that multiple diverse species of bats are co-mingling in caves together [*]Multiple species of coronaviruses are co-mingling together in the same individual bat species [*]Coronaviruses are very capable of recombination of genetic material (sharing of bits and pieces of different viruses during replication to form a very genetically-distinct virus compared to the two viruses the material was derived from_...see slide at 33:15 of the presentation [/LIST] All these findings make it [B][U][I]perfectly plausible[/I][/U][/B] that, through recombination events, a coronavirus with only 78% overall homology to the original SARS-CoV virus can find its way into humans either directly or through another animal vector. Especially if it picks up a gene that encodes for a viral spike protein that allows it to bind to the ACE2 cell receptors found in human, bat, civet, and mouse cells. This picture (screenshot from the slide at 52:06) shows this...There are 14 sites on the ACE2 protein that (based on research to date) seem most important for the virus to bind to it. Anywhere you see green means that virus can bind to that site reasonably well. SARS-CoV-2 has 8/14 sites common with the original SARS virus. And as Dr. Baric notes, those differences between SARS-CoV-2 and original SARS actually appear to make it bind [B]BETTER [/B]than the original SARS virus to ACE2. [ATTACH type="full"]51997[/ATTACH] See my discussion above, which explains why [B]TOTAL [/B]similarity is not as important and similarity of the key virulence genes that the viruses contain. Best, JBM [/QUOTE]

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