Thread by @MackayIM

@TwinTurboCe1ica @chrismartenson @OshZosh @jamesross @ProSuja Okay. I can't spend any more time on this now. But I'll get back to you with an idea I'll follow up when I'm not on the clock.

@TwinTurboCe1ica My few thoughts on the polybasic cleavage site in Spike.
We don't know precisely where it came from and its outside my area of expertise to guess.
But I lean to the history here over manmade/manipulated. Why? Reasons...

@TwinTurboCe1ica 1. We clearly haven't yet adequately sampled the family Coronaviridae.
2. We have linked all other CoVs that infect humans so far, to a zoonotic origin. Wh not again this time-some public & politicians mainly, not experts-don't make sense except for political gain

@TwinTurboCe1ica 3. The preprint referred to in the video link you sent me earlier, from chinaxiv (chinaxiv.org/user/download.…) has a nice picture in it. We see that *many* CoVs, of those we know about, do have some form of likely furin-cleavable polybasic sequence. Maybe a 3rd (of this tree) don't

@TwinTurboCe1ica ...Perhaps rather than SARS-CoV-2 being the odd one out, the other sarbecoviruses are the odd ones out? Keeping in mind there doesn't appear to be a huge explanation ascribed to recombination in the history of SARS-CoV-2 as I understand it anyway, to explain this site

@TwinTurboCe1ica 4.The recently discovered bat CoV, RmYN02 (GISAID EPI_ISL_412977; biorxiv.org/content/10.110…), also has some bases in the cleavage site region of SRS-CoV-2 - far from identical but more than the pangolin and RaTG13 CoVs.

@TwinTurboCe1ica And, as the authors including @edwardcholmes note, this lends support their *natural* occurrence.

The Prof could speak much more authoritatively to the specifics of these points and all of this concept, but he might be a little busy these days! 😉