Twiv 815 45

```
45:01 so what they have done is the following
45:03 they have uh screened
45:07 15 mars you know amino acid segments of
45:10 15 uh peptides let's say or 15 amino
45:13 acids
45:15 on the glycoprotein
45:17 so they took each of them and they
45:19 probed their t-cell reactivity
45:23 and they observed this in patients
45:26 that have not been exposed to sars co2
45:30 so
45:31 so these are i have again a slide here
45:33 but i can explain
45:35 so what happens is that there are many
45:37 segments actually on the spike
45:40 that showed a very high teaser
45:42 reactivity
45:43 so the explanation is that
45:46 some of those
45:48 peptides are already shared
45:50 with previous stars viruses or common
45:53 cold viruses
45:55 and there might be some people who have
45:57 gained some kind of immunity you know
46:00 and that might also explain the
46:02 differences between individuals i seem
46:04 to remember that
46:06 some of the variants have amino acid
46:08 changes near
46:09 the
46:11 this fear and cleavage site does does
46:13 that make any difference in terms of
46:15 being a super antigen do you know
46:17 so
46:18 you just read my mind you know we are
46:20 going to continue on that time okay so
46:23 yvette there was one
46:25 one slide you showed about the prr you
46:28 know the the the the poly basic side
46:31 binding to the tcr
46:33 uh if you if you get the uh um you know
46:36 uh the
46:36 uh uh
46:37 the binding uh comp you know like
46:40 structural binding
46:42 that you showed earlier
46:44 at the beginning
46:46 and number 13
46:48 i think
46:50 yeah that one
46:51 yeah
46:53 and
46:54 so you see in the middle
46:56 p681
46:59 and
47:00 all the mutations were just like outside
47:03 of this but when the delta mutant came
47:07 p681 becomes you know r right you know
47:10 like uh and so because the the motif
47:13 armor this motif that we discover is
47:15 becomes even more
47:17 as more basic even more basic
47:20 so even more basic means that now you
47:22 can have you know attached to the acidic
47:25 fury and much more therefore you cleave
47:28 you have much more cleave i think
47:30 several people
47:31 you know jason mclean and others that
47:33 you invited i think have talked about
47:35 this that that delta variant may cleave
47:38 much much more therefore two things
47:41 happen you make more s2 and you know
47:43 more infection and perhaps more virus
47:46 levels and perhaps that explains the
47:48 transmissibility increased
47:50 transmissibility but what people are
47:52 forgetting is
47:54 there's also more s1 and more s1 is shed
47:57 this is like almost like a viral toxin
48:00 kind of concept you know in
48:02 in what eva harris you know when i
48:04 talked about in one of the twins that
48:06 you had you know like ns1 from the flemi
48:09 viruses that are being released so we
48:12 proposed that s1 is like a
48:15 and also viral toxin that is being
48:16 released
48:18 and uh so now here's an observation
48:22 so that requires to think that
48:26 delta is causing much more severe
48:28 disease
48:29 if that's hypothesis is correct and i
48:32 think there are at least five papers
48:34 that are showing that uh there's more
48:37 hospitalization you know with with delta
48:40 i mean no clear paper shows that there's
48:42 more severe except hospitalization but
48:45 there is a very interesting observation
48:47 i want to link to mystique so you know i
48:50 want to
48:51 go back to this concept you know where
48:54 actually at least on my end everything
48:56 started
48:57 that was uh you know we were focusing on
49:00 this region of the starscope to where
49:03 there is a prra in search
49:06 right in the segment and this is uh
49:08 followed by the cleavage site rs
49:11 now all other family members
49:14 actually mers has also a segment here
49:16 but um many other sas of two family
49:19 members they don't have uh so this is an
49:22 insertion
49:23 so that is uh that's extremely reactive
49:26 you know you see there are
49:28 one two three arginines here
49:31 in the delta variant
49:33 there is one more arginine coming into
49:36 place so such a highly
49:39 basic region is extremely reactive
49:42 so it would but now i think uh what
49:45 moshe also brought up is
49:47 the reactivity to with uh
49:50 the
49:51 antibody might be increasing but also we
49:55 have the reactivity with the furion or
49:57 the protease that
50:00 does the cleavage at this position right
50:03 so when we were trying to interpret the
50:05 results how the
50:08 antibody is inhibiting
50:10 the virus or it's uh the spike the
50:14 glycoprotein from from
50:17 infecting human cells
50:19 then we also started to think more
50:22 closely about you know what is happening
50:24 we know that we are talking about this
50:27 cleavage site just the vicinity the near
50:29 neighborhood
50:31 and we know that uh okay 63 this
50:34 antibody similar to
50:36 16 which has been discovered for sev
50:39 6b3 is reducing viral entry that's our
50:43 interpretation from of the experimental
50:46 data
50:47 but we are talking about the s1h2
50:49 proteolytic cleavage site at the same
50:51 time
50:52 and then we
50:54 now look more closely what is happening
50:56 there
50:57 so the spike itself
51:00 uh it's the same exactly the same region
51:03 where the tcr and the antibody binds it
51:07 also binds this uh
51:08 human protease
51:11 or furin you know tian prss2 or fury
51:14 they both bind at the same position
51:17 and
51:18 they also you know exploit those uh
51:20 basic residues to have a very tight
51:23 binding high affinity
51:26 and then
51:27 if this is the case
51:28 there is a competition
51:30 between the antibodies 63
51:33 and those
51:34 proteases
51:36 that all try to bind this insert pr the
51:39 vicinity of this insert right
51:41 and then when we
51:43 then we started to calculate what's the
51:45 binding affinity
51:47 and it turns out that when you calculate
51:50 the binding affinity between the spike
51:52 and those proteases
51:54 versus the spike and the antibody
51:57 we found that the antibody binding
51:59 affinity is comparable to that of urine
52:02 one of the proteases the other one has a
52:05 weaker binding
52:07 propensity
52:08 so
52:09 in this image where i i have shown both
52:12 the 63 and young campy rss to the
52:15 protease
52:17 bound to the
52:19 spike of course this never happens
52:22 because i just superimposed them
52:25 virtually
52:26 because they are competing exactly for
52:28 the same site
52:30 so one possible way
52:33 that we have observed less impactivity
52:36 in the presence of 63
52:38 is that
52:40 that region
52:41 then was
52:43 at least partially blocked by 63
52:46 and there were a few were furious
52:48 molecules or proteases binding there so
52:51 we came up with this hypothesis that you
52:54 know
52:55 63 will effectively compete
52:58 with proteases that interfe that's
53:01 interfering with the proteolytic
53:02 cleavage
53:03 which is essential
53:05 for the fusion peptide to be released
53:07 and for you know entering the host set
53:10 yeah
53:12 so so i want to go back one minute to
53:14 the uh the delta mutation so and i can i
53:18 can answer uh uh instance question
53:22 six
53:23 681 mutation you know like p becoming r
53:27 um so i just said that one of the
53:29 consequences would be that there will be
53:31 more cleavage and then there will be
53:33 more s1 uh when there is more s1 you
53:37 would expect
53:38 to have more severe disease
53:40 the only thing i can tell you from the
53:42 miss see as a clinician is that
53:45 since delta the uh
53:48 waves started
53:51 we have seen tremendous amount of
53:53 pediatric cases that shoot up you know
53:55 like shut up you know like really you
53:57 can go to the cdc missy
54:00 website and you can see
54:02 cases of pediatric cases and the misc
54:05 cases exactly follow each other in the
54:08 prior prior uh
54:11 surges with the alpha with the you know
54:15 with with the uh alpha beta and the
54:17 other other variants
54:19 but with
54:20 delta
54:21 we're now seeing
54:23 severe
54:24 young kids coming with severe pneumonia
54:27 to the icus
54:29 and not
54:30 missing so you could see that
54:33 the curve that cdc has on their website
54:36 shoots up the pediatric cases but the
54:38 misty is down so the my hypothesis for
54:42 that it fits together with the pa what
54:44 we're seeing here as a clinician we
54:46 don't see much missy anymore we keep
54:48 seeing acute severe disease which we
54:51 didn't see before what was the history
54:53 of we see very mild
54:55 disease initially and then six weeks
54:58 later four weeks later severe messi now
55:01 very severe disease at the beginning and
55:03 no missing
55:05 in my opinion that's because of perhaps
55:08 the 681 is doing something that mutation
55:11 and pushing the
55:13 the more uh uh uh
55:16 shed
55:17 spike
55:18 that is causing more initial severe
55:20 disease and when you push so much th1
55:23 and so much severe disease perhaps the
55:25 body
55:26 turns off the autoimmune part for later
55:28 because you're just like dealing with
55:30 the acute disease initially more but
55:32 this is a very interesting observation
55:35 the opposite of what you would predict
55:37 right
55:38 opposite what you would have predicted
55:39 yeah
55:40 i assume there are no animal models of
55:42 miss c that you could test all of this
55:43 in right
55:46 no no but but but we're trying to give
55:49 spike to ma and then see what happens
55:51 with repeated spike to see if there's an
55:53 autoimmune
55:54 autoimmune thing yeah
55:56 so the question that was uh on my mind
55:59 the whole time i was reading this stuff
56:01 is what about vaccination
56:03 uh why doesn't vaccination trigger a
56:06 superantigen response
56:08 uh or you know maybe there is something
56:10 about vaccination
56:12 something i think i wrote to vinson one
56:14 day i think they
56:16 david walt with alanna ogata published
56:19 another paper uh where they uh measured
56:23 circulating uh s1
56:26 after vaccination and they have found
56:28 that you know in the first eight days
56:31 there's a small amount 50 microgram you
56:33 know 70 80 microgram you know of of
56:37 circulating s1
56:40 after vaccination
56:42 for the first vaccination and the second
56:44 vaccination they couldn't because maybe
56:46 antibodies you know interfere with their
56:48 elisa
56:49 that may play a role in you know maybe
56:52 the headache and the side effects
56:55 but but it's not enough or sustained and
56:58 you probably need the rest of full viral
57:01 disease to really
57:03 cause this and not just like one spike
57:05 or for a few days or something and
57:08 that's the only explanation i have
57:10 so one other thing is you know if you
57:12 look at the literature
57:14 all the structures claudium structures
57:16 that have been resolved for the spike
57:19 they have replaced this prra segment
57:22 mutated it
57:23 because this is a highly reactive and
57:25 flexible region that doesn't land itself
57:28 to structural stabilization
57:30 so uh i i'm not sure but we may want to
57:34 check whether in the vaccine the
57:36 sequence that is being used
57:39 did they keep the prra segments which is
57:41 uh you know highly super antigenic or
57:44 not i need to i i think we need to check
57:46 that's a very good question though i
57:48 think i know this you know uh because i
57:51 talked to jason mcloone about this and
57:53 and i think the prra
57:56 uh uh motif was uh a change mutated
58:02 in the johnson and john
58:04 in the johnson and johnson vaccine and
58:06 the novovac vaccine not the other ones
58:08 oh interesting interesting yeah
58:11 but the the the mrna vaccines have a
58:14 c-terminal two prolines added right what
58:17 does that does that interfere with the
58:19 uh the site if you're inside at all or
58:21 is it distant from it
58:23 the terminal will be at the s2
58:25 it's too far okay
58:27 c2 okay
58:30 but before before we uh uh you know i
58:33 don't know when you want to wrap this up
58:36 i just want
58:38 yvette to to show us
58:40 in my mind what is the most
58:43 interesting observation
58:45 she made which are the neurotoxins
58:48 but i i think we ran out of time
58:51 well you you were uh welcome to to stay
58:54 on it's i just was being respectful of
58:56 your time um okay so sure i can show
58:59 very quickly uh
59:01 you know when we
59:02 did the analysis uh because you know we
59:06 didn't know where to look at in the very
59:08 beginning
59:09 so we
59:10 scanned all the sequence
59:13 and uh you know that was a study
59:16 from
59:17 the lab of uh jun wu and others in the
59:20 year 2004
59:22 that's
59:23 published in viral immunology
59:25 uh after sars the first star pandemic
59:29 and they were they looked at uh whether
59:32 they had there were any superantigenic
59:34 toxin-like or adhesive uh molecule-like
59:37 segments
59:39 in sars uh
59:41 one you know the first one
59:43 and then uh they did identify that a
59:46 bunch of motifs including a few
59:49 neurotoxin motifs
59:51 uh here highlighted in green
59:54 now
59:55 we checked whether those motifs were
59:57 conserved
59:59 in star score with two

```