SA, Dredd, what do you make of this?
Superantigenic character of an insert unique to SARS-CoV-2 spike supported by skewed TCR repertoire in patients with hyperinflammation
PNAS October 13, 2020 117 (41) 25254-25262
http://www.pnas.org/content/117/41/25254
– “The binding epitope on [the SARS-CoV-2 spike glycoprotein] harbors a sequence motif unique to SARS-CoV-2 (not present in other SARS-related coronaviruses), which is highly similar in both sequence and structure to the bacterial superantigen staphylococcal enterotoxin B”
Staphylococcal enterotoxin B – SEB – is pretty nasty. It’s produced by staphylococcus bacteria, of course, but was also developed as a bioweapon:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5086421/
– “Staphylococcal enterotoxin B (SEB) is the prototype of a non-egc-associated potent SAg. It is categorized as a category B select agent because it is the most potent staphylococcal enterotoxin, and much lower quantities are sufficient to produce a toxic effect than with synthetic chemicals. Furthermore, SEB is extremely stable and easily produced in large quantities. At low concentrations, SEB can cause multi-organ system failure and death. During the 1960s, when the United States had an offensive biological warfare program, SEB was studied as a biological weapon and stockpiled with various other bioweapons prior to its destruction in 1972 (4). Based on those investigations, the effective dose of SEB that would incapacitate 50% of the exposed population was estimated to be 0.0004 μg/kg of body weight, whereas the 50% lethal dose was estimated to be 0.02 μg/kg of body weight for humans exposed by the inhalation route”
Obviously viruses can’t make any proteins themselves, so in some cases, thankfully rare so far, SARS-CoV-2 is inducing hosts’ own cells to make SEB or something very similar to it. Do you know if harbouring something like this is common for viruses?