I thought the mRNA vaccines encoded the prefusion spike that was locked in place and stable against cleavage? It was shocking to see that high levels of S1 were reported. If I'm not mistaken, S1 is much more pathogenic than full spike.
I believe the prefusion conformation may be in reference to its ability to bind to ACEII receptors, although the prefusion/postfusion state may be necessary for making the furin cleavage site accessible.
I'm not too sure about the different states with respect to FCS, but if it does affect it then yeah that would be weird.
The stabilization just makes it so S2 doesn't change conformation after cleavage. Nothing is done to any of the cleavage sites, so cleavage is not affected. If the spike is a harpoon gun, then instead of locking the "cap," they locked the harpoon.
So spike can't perform fusion, and you don't get antibodies to post-fusion forms. But S1 still flies off.
In a lab, 2P makes it easier to do cryo-EM so it probably makes S1 somewhat less prone to fall off. That doesn't matter when you've got spike just hanging off of endothelial cells waiting for other molecules to attract it.
That makes sense. But, I guess it does make me wonder what kind of unnatural epitopes would be presented on the S2 fragment that is locked in prefusion configuration after S1 splits off.
Whereas natural immunity gives you antibodies to the post-fusion. This is probably good since it means your immune system is still flagging fused spike for destruction. But what's good in natural immunity might not be good for injected immunity given the classic example of RSV vax ADE (which is attributed to the inactivated RSV virus having a bunch of deformed spike).
I have been mulling over what the puzzle piece means, hence not making a post on it.
Rather than a difference in cleavage, I think the question is why spike would be circulating instead of bound to the membrane of transfected cells. So it may just be that the spike is released when transfected myocardiocytes are blown up by the immune system.
Not satisfied, is why that would be specific to myocarditis. You would think there would be a tolerated level of cellular destruction and whole spike release in all recipients. Especially given that the spike-positive case kids were sampled days after symptom onset which would suggest spike isn't transient.
All I come up with is that suggests serious disparities in "bolus," though not necessarily due to IM as opposed to product variability. I would say both are likely at play. So the lack of circulating spike in the control group reflects that they had much less dosage and dispersion so the cell-killing-released spike is at trace levels. Meanwhile you can still have myocarditis without a huge dose/dispersion, since there's variability in dispersion. So "bolus" isn't everything.
Actually, if we sort of consider the fate of the spike, it's only been assumed that the spike gets moved to the surface of the cells, but we don't have much evidence of the frequency of that do we?
I'm a bit curious if the lack of other viral proteins may actually be an issue here, since several of the proteins are involved with processing of the spike? I think all of this is a serious issue in discrepancies between hypothetical models and the actual processes. Again, all speculative. 🤷♂️
I was busy with my microbiome posts so I left it to the side but perused it a few times. The results of the spike were one of the weirdest parts and I tried at adding some context that I could.
I am really not sure about the whole spike aspect. I'm not too deep in immunology so I was curious if phagocytosis or cell lysis may cause it to be released? I thought that the results for innate immune activation may suggest the way that the transfected cells are dealt with may be different than the adaptive immune responses possibly.
I just tossed out the TMPRSS2 as it was the only protease I'm aware of that cleaves the FCS, so I was wonder why there were some S1 and some full spike in participants, and so I just made some assumption about spike processing having to occur.
I think it's figuring out the "barriers of entry" before the spike enters the blood. It's possible that the same dosage for younger people may not provide enough sponge or barriers for the same level of spike in adults? They comment that the clearance of spike may be quicker in adults because of size so there's a good deal of metabolism and immunological differences that should be considered.
Jan 21, 2023·edited Jan 21, 2023Liked by Modern Discontent
[replying to wrong comment] Right - we don't know anything in vivo. In vitro it does seem to be confirmed to go in the nucleus, besides ER and cell surface. https://www.biorxiv.org/content/10.1101/2022.09.27.509633v1 I am sure that the experience of spike in the cell is highly influenced by other viral proteins. OTOH there might be a lot of "auto-pilot" features for how S1 behaves after cleavage on the cell surface.
Ugh, I'm having a growing resentment of the word "novel" to be quite honest...
I've seen a few studies suggesting that several proteins help in the spike processing, although I can't recall where I saw it.
I think my biggest issue with this S1/S2 stuff is that I can't inherently visualize these things and so I'm having a bit of trouble fully understanding the scope of this stuff.
I'm not sure if you noticed, but apparently there are a few studies adding even more proline residues to make the spike even more stable, because apparently two wasn't enough. I'm curious if this may suggest that the proline substitutions may not have been effective at stopping spike activity.
I thought the mRNA vaccines encoded the prefusion spike that was locked in place and stable against cleavage? It was shocking to see that high levels of S1 were reported. If I'm not mistaken, S1 is much more pathogenic than full spike.
I believe the prefusion conformation may be in reference to its ability to bind to ACEII receptors, although the prefusion/postfusion state may be necessary for making the furin cleavage site accessible.
I'm not too sure about the different states with respect to FCS, but if it does affect it then yeah that would be weird.
Kirchdoerfer et al. reported the following in regards to cleavage of S-2P:
"examination of the structure models indicates no significant differences between the trypsin-cleaved and uncleaved SARS-CoV S 2P"
https://www.nature.com/articles/s41421-022-00419-w
That suggests to me that S1 and S2 fragments are not generated when the stabilized prefusion spike is cleaved.
The stabilization just makes it so S2 doesn't change conformation after cleavage. Nothing is done to any of the cleavage sites, so cleavage is not affected. If the spike is a harpoon gun, then instead of locking the "cap," they locked the harpoon.
So spike can't perform fusion, and you don't get antibodies to post-fusion forms. But S1 still flies off.
In a lab, 2P makes it easier to do cryo-EM so it probably makes S1 somewhat less prone to fall off. That doesn't matter when you've got spike just hanging off of endothelial cells waiting for other molecules to attract it.
That makes sense. But, I guess it does make me wonder what kind of unnatural epitopes would be presented on the S2 fragment that is locked in prefusion configuration after S1 splits off.
Seems to have been successful at keeping antibody responses specific for the stabilized conformation https://www.science.org/doi/10.1126/sciimmunol.adf1421
Whereas natural immunity gives you antibodies to the post-fusion. This is probably good since it means your immune system is still flagging fused spike for destruction. But what's good in natural immunity might not be good for injected immunity given the classic example of RSV vax ADE (which is attributed to the inactivated RSV virus having a bunch of deformed spike).
With every passing day I am more and more thankful that I didn't inject my kids.
I have been mulling over what the puzzle piece means, hence not making a post on it.
Rather than a difference in cleavage, I think the question is why spike would be circulating instead of bound to the membrane of transfected cells. So it may just be that the spike is released when transfected myocardiocytes are blown up by the immune system.
Not satisfied, is why that would be specific to myocarditis. You would think there would be a tolerated level of cellular destruction and whole spike release in all recipients. Especially given that the spike-positive case kids were sampled days after symptom onset which would suggest spike isn't transient.
All I come up with is that suggests serious disparities in "bolus," though not necessarily due to IM as opposed to product variability. I would say both are likely at play. So the lack of circulating spike in the control group reflects that they had much less dosage and dispersion so the cell-killing-released spike is at trace levels. Meanwhile you can still have myocarditis without a huge dose/dispersion, since there's variability in dispersion. So "bolus" isn't everything.
Actually, if we sort of consider the fate of the spike, it's only been assumed that the spike gets moved to the surface of the cells, but we don't have much evidence of the frequency of that do we?
I'm a bit curious if the lack of other viral proteins may actually be an issue here, since several of the proteins are involved with processing of the spike? I think all of this is a serious issue in discrepancies between hypothetical models and the actual processes. Again, all speculative. 🤷♂️
I was busy with my microbiome posts so I left it to the side but perused it a few times. The results of the spike were one of the weirdest parts and I tried at adding some context that I could.
I am really not sure about the whole spike aspect. I'm not too deep in immunology so I was curious if phagocytosis or cell lysis may cause it to be released? I thought that the results for innate immune activation may suggest the way that the transfected cells are dealt with may be different than the adaptive immune responses possibly.
I just tossed out the TMPRSS2 as it was the only protease I'm aware of that cleaves the FCS, so I was wonder why there were some S1 and some full spike in participants, and so I just made some assumption about spike processing having to occur.
I think it's figuring out the "barriers of entry" before the spike enters the blood. It's possible that the same dosage for younger people may not provide enough sponge or barriers for the same level of spike in adults? They comment that the clearance of spike may be quicker in adults because of size so there's a good deal of metabolism and immunological differences that should be considered.
[replying to wrong comment] Right - we don't know anything in vivo. In vitro it does seem to be confirmed to go in the nucleus, besides ER and cell surface. https://www.biorxiv.org/content/10.1101/2022.09.27.509633v1 I am sure that the experience of spike in the cell is highly influenced by other viral proteins. OTOH there might be a lot of "auto-pilot" features for how S1 behaves after cleavage on the cell surface.
I just remembered the exosomes paper. Went back to look, they used S2 antibody. And all 8 volunteers were positive well after the 2nd dose. But that was after filtering for exosomes and then blotting. So once again it could be a question of trace loads vs. super-loads. https://journals.aai.org/jimmunol/article/207/10/2405/234284/Cutting-Edge-Circulating-Exosomes-with-COVID-Spike
Ugh, I'm having a growing resentment of the word "novel" to be quite honest...
I've seen a few studies suggesting that several proteins help in the spike processing, although I can't recall where I saw it.
I think my biggest issue with this S1/S2 stuff is that I can't inherently visualize these things and so I'm having a bit of trouble fully understanding the scope of this stuff.
I'm not sure if you noticed, but apparently there are a few studies adding even more proline residues to make the spike even more stable, because apparently two wasn't enough. I'm curious if this may suggest that the proline substitutions may not have been effective at stopping spike activity.
https://pubmed.ncbi.nlm.nih.gov/35994646/
I guess I'll shoot a post out on it since the paper's not getting any newer.