I'm agnostic on its various hypotheses about mechanisms of origin of furin-cleavage sites, but the part of this paper that suggests furin-cleavage site might be present in two of these SARSr-CoVs as a minor variant is embarrassingly bad science that shouldn't be amplified. (1/n)

Here is Table 1 of pre-print (https://t.co/7fQsreN77n) that shows data related to this claim. The mutations in question are present at 0.004% and 0.006%, corresponding to 6 or 7 Illumina reads out of >100,000 total. (2/n)
There are good deep-sequencing studies of CoVs, eg by @katrina_lythgoe (https://t.co/joX4kCqOEh), @LauringLab (https://t.co/TisAPvkCVp) & @KATarinambraun @tcfriedrich @trvrb @LouiseHMoncla (https://t.co/08EhfVAAL1). These studies find you can call variants to 2-3% frequency (3/n)
Table 1 of this pre-print is reporting "mutations" that introduce a furin-cleavage site at frequencies of 0.004% to 0.006%, which is orders of magnitude lower than what good studies have rigorously defined as a reasonable threshold (2-3%) to call mutations. (4/n)
As anybody who has ever analyzed viral or cancer deep sequencing knows, it's simply impossible to use standard Illumina sequencing to identify mutations at even 0.4% or 0.04%, let alone 0.004%. It's actually surprising when a given sequencing error isn't present at ~0.01%. (5/n)
So what this study should say is: we found some bat SARS-related CoVs that are just one or a few mutations away from having a furin cleavage site, but none of them actually have a furin cleavage site even as a minor variant. (6/n)
Above point also currently caveated, since pre-print only shows 10-codon chunk of BB99-04 & no sequence of BB89-98. This region of spike is subject to substantial alignment uncertainty, so withhold judgment until enough of the sequences released to support the alignments (7/n)

More from All

https://t.co/6cRR2B3jBE
Viruses and other pathogens are often studied as stand-alone entities, despite that, in nature, they mostly live in multispecies associations called biofilms—both externally and within the host.

https://t.co/FBfXhUrH5d


Microorganisms in biofilms are enclosed by an extracellular matrix that confers protection and improves survival. Previous studies have shown that viruses can secondarily colonize preexisting biofilms, and viral biofilms have also been described.


...we raise the perspective that CoVs can persistently infect bats due to their association with biofilm structures. This phenomenon potentially provides an optimal environment for nonpathogenic & well-adapted viruses to interact with the host, as well as for viral recombination.


Biofilms can also enhance virion viability in extracellular environments, such as on fomites and in aquatic sediments, allowing viral persistence and dissemination.

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🌿𝑻𝒉𝒆 𝒔𝒕𝒐𝒓𝒚 𝒐𝒇 𝒂 𝑺𝒕𝒂𝒓 : 𝑫𝒉𝒓𝒖𝒗𝒂 & 𝑽𝒊𝒔𝒉𝒏𝒖

Once upon a time there was a Raja named Uttānapāda born of Svayambhuva Manu,1st man on earth.He had 2 beautiful wives - Suniti & Suruchi & two sons were born of them Dhruva & Uttama respectively.
#talesofkrishna https://t.co/E85MTPkF9W


Now Suniti was the daughter of a tribal chief while Suruchi was the daughter of a rich king. Hence Suruchi was always favored the most by Raja while Suniti was ignored. But while Suniti was gentle & kind hearted by nature Suruchi was venomous inside.
#KrishnaLeela


The story is of a time when ideally the eldest son of the king becomes the heir to the throne. Hence the sinhasan of the Raja belonged to Dhruva.This is why Suruchi who was the 2nd wife nourished poison in her heart for Dhruva as she knew her son will never get the throne.


One day when Dhruva was just 5 years old he went on to sit on his father's lap. Suruchi, the jealous queen, got enraged and shoved him away from Raja as she never wanted Raja to shower Dhruva with his fatherly affection.


Dhruva protested questioning his step mother "why can't i sit on my own father's lap?" A furious Suruchi berated him saying "only God can allow him that privilege. Go ask him"