Charles Jillings, CEO of Utilico, energized by strong economic momentum across Latin America. Watch the video here.
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No FOMO Friday and at some kind of support I think. November is almost here surely this is the month. Come on Sir Al!!
This was to get rid of the mucin , not bind S1.
You could bind S1 as a clean up but then the buffer you would need to release it would stop it binding in the LFT. (or you could leave it bound and then bind a second Affimer with a reporter - but you then get a sandwich ELISA - which they already have!)
After a bit more reading the mucins self polymerise so they could be depleted in part, by filtration. It will be interesting to see what they do use pre LFT.
Good point Monk
You wouldn’t need LFT’s, just put the finished solution into a simple test tube , add saliva, shake up, maybe change colour when the Affirmer catches the spike?
Strangely, this then links to the other aspect of Avacta, targeting cancers (although may need a different specificity).
Monoclonal antibodies, reactive with mucin glycoproteins have shown promise clinically for the diagnosis and classification of breast tumours, and they may also be used therapeutically for tumour targeting.
https://cancerres.aacrjournals.org/content/canres/48/8/2138.full.pdf
Perhaps they should coat the collection tubes with Affimers that bind mucin proteins?
Another product to market??
I just had a quick read, the viscosity comes from mucins. These are glycoproteins which is essentially what the S1 is, this makes it harder to have a prep method that separates them (pre LFT). I would think that it could also give problems with the HGPR type assays.
I can see why it is tricky getting good assays.
http://www.vivo.colostate.edu/hbooks/pathphys/topics/mucins.html
I don't think that they have any issues with mutation at the moment. I though that it was more about scaling production?
With regards saliva and LFT have a look at this -(it has been posted before I think)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469882/
And for a solution to get better samples....
https://4saliva.com/products/pure-sal/
Monk, could the technical issues that have had to be considered been more around the buffer solution /saliva, rather than tracking the RNA genetic mutation ? The latter being important but the lesser of the two.
Listening to Klaus this week it does highlight just how complexed the process actually is, especially with the density of the buffer and people’s different consistency of saliva and of course the temperature / humidity of the location the test is being taken , ie if it’s too thick the Affirmer may not pick up the spike protein of C19 in say the early days of infection we are targeting ditto not withstanding the paper as well, this has to be considered, the buffer needs to flow just the right amount?
Almost Goldilocks style fine tuning.
What’s your thoughts on this thesis?
Fard, I agree. but I would not want to overstate mutation being a major problem.
The initial screen took 4 weeks but to scale production and incorporate them in an assay, probably longer?
However, I doubt they would wait, they probably have already selected others. I think that they already have them for the nucleocore protein as well. As I said yesterday, there is a lot of sequence data now to see what is tightly conserved, so with careful selection the issue of mutation at the binding site can be minimised. A similar rational is used when selecting primer sequences for PCR.
Monkshood/Jaylarc - thanks, very interesting discussion. Looking at it another way however, would it not actually be fairly straight forward in practice for AVCT to deal with new emerging variants? Through April it took them a matter of weeks to identify the affimers appropriate to the then dominant strain. So presumably new affimers for any new variant could be very quickly identified and substituted for the original ones. On the one hand this sounds very simplistic. But I cannot imagine that the switching of affimers would make any difference to the dynamics of liquid flow in the device, wicking through the membrane, etc. And I doubt there would need to be any changes with the other reagents, buffers etc? Assuming the current approval process has all been completed, CE approval gained and the LFD in its initial iteration has been launched and is in use, then presumably the main work in switching to a new set of affimers would be limited to re-affirming S & S in another set clinical trials? Four weeks or so maybe? Always the optimist!
Monkshood cheers for the reply, you certainly know your stuff.
I think that link and to an extent your post are a tad beyond my skill set.
I didnt see it as a concern for our testing prospects but interesting nonetheless.
Cheers
Jaylarc, I had seen this but not found any further details. They clearly believe it is a feasible way.
I have not done much with glycoproteins, however, my concern is that although they say ' the chains of sugars are constant' my understanding is that the sugars and level of glycosylation can be variable and are dependant upon the host cell.
From the link below-
'A mixture of oligomannose- and complex-type glycans can be found at sites N61, N122, N603, N717, N801, and N1074 (Fig. 2). Of the 22 sites on the S protein, 8 contain substantial populations of oligomannose-type glycans, '
It is the one of the things that I would like to know about the BAMS assay, you could select a couple of tryptic peptides which are not glycosylated (this involves a slow sample work up), but if you look at the intact S1 protein (fast), then you will have multiple glycosylation states (therefore different m/z's), it may be that in practice you just get a broad peak which is still unique enough to be diagnostic . It is why I asked for details - but he never answered this part of the question.
https://science.sciencemag.org/content/369/6501/330
Monkshood what do you think HPGR (Host-Pathogen Glycan Recognition)
Different approach from Iceni re mutations, I think they were mentioned here before?
It looks a very interesting little company, unfortunately a limited co. although they were seeking angel investors about a year ago, if you were willing to stump up from 100k.
Iceni Diagnostics is developing a new approach that identifies the virus - not by its genetic code, which can mutate, but by using its reliance on chains of sugars which are constant and unchangeable.
https://www.icenidiagnostics.com/news/rapid-covid-19-detection-iceni-diagnostics-offers-new-approach/
https://www.med-technews.com/news/iceni-appoints-bbi-to-produce-batches-of-covidflu-detection-/
Thanks Monkshood. I’d be grateful if you’d tell us what that means. Are we in good shape?
The only way an Affimer could directly detect a mutation is if it specifically bound to the epitope generated by the new AA (and not the old), or by loss of function i.e. it bound the original but not the new one.
You could see some mutations by MS following affinity purification by an Affimer - but that is a different thing.
I have only seen reference to AS saying that binding of the Affimers they are using is not affected by the G614D mutation.
Or have I missed something ?
Forever, no idea, I think most are using mAbs so it would be a similar issue, tests using pAbs (polyclonal antibodies)bind more sites so it would reduce the mutation problem but they usually have more problems with lack of specificity.
The virus is being sequenced at multiple sites all of the time. Changes would be quickly flagged, they could potentially affect PCR as well (if the mutation was at the terminus of the primer site) so it is not entirely unique to protein detection based systems.
Affimers do detect the mutation, as advised by AS.
Thanks for the information.
In simple terms - is it more likely the current affimer would attach to the new mutation or the antibodies used in other tests? I know its probably not possible to answer... But are affimers sometimes TOO specific compared to antibodies - which would may attach to more mutations?
CO, not my area but I think it has a 'proof reading' complex that corrects sequence replication mistakes and so has a lower mutation rate than some viruses.
I am sure the initial screen of the Affimers would have been just to find a pair of specific binders.
There will however, be some binding site of the S1 which are not variable, they have now had quite a bit of time now to select for ones that bind these regions, (it may be the ones they have already do), provided that they can get the specificity then these would be quite durable.
I think the test requires a flux capacitor
Good heads up, thanks.
As I read this I was coming to that same thought, Monkshood... If you make a very effective test that is massively adopted and becomes pivotal in getting the virus under control, then yep, there would be a selective evolutionary pressure towards any mutation that lets it slip through that net undetected...
Worrying, but probably not an investment risk. At least if the Avacta LFT is widely adopted enough to drive evolution of the virus, it will already have been a commercial success, and as you say, it might only be a case of finding a new binding Affimer and bringing that into the test, in which case Avacta should be quicker to act than the competition using mAb’s. The supply chain and development process would be already nailed down to expedite release.
How’s the mutation rate in this virus anyway? I thought I read somewhere it was relatively low.
Monk... what a thought !
A mutant SARs- COV- 2 variant
There’s a movie in that one
That is most helpful - confirms what I thought could be the case but I was approaching it from an engineering perspective which would not go down well here!
Worth a look through the paper .
Without casting aspersions, it does seem that people going on holiday to Spain in the summer has had quite an impact...
Yep Oke, it's watching evolution in practice.
Interesting thought, if you had a test that missed a mutation, that strain could become more prevalent , you would then drive 'evolution' with your diagnostic .
A second new variant 20A.EU2 with mutation S:S477N would not be detected.
Amino acid changes are important when it comes to using Affimers and mAbs in diagnostics. As was pointed out in the last presentation, the G614D does not affect either of their two Affimer S1 binding sites, it cannot be ruled out that other changes may.
They must by, know which AA's are key for binding of the two they are using and could look at the potential for mutation at these sites. The ability to screen lots of Affimers plus their small size, which gives access to smaller epitopes (cheers PL), should give them an advantage over mAbs for selecting the most suitable.
You would not want to make the tests then find that a new variant does not bind!