The latest Investing Matters Podcast episode featuring Jeremy Skillington, CEO of Poolbeg Pharma has just been released. Listen here.
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It’s great news that a rapid population test is at last available. Whilst swab testing is inherently flawed (my earlier post) at least it’s something for those with nothing and hopefully repeat testing will help eradicate errors.
Trek
@TonyFawcett The Daily Mail is just picking up on a World Health Organisation Press Release. The Guardian ran the story yesterday afternoon.
The two tests mentioned are NOT using Avacta Affirmers.
If you look at WHO's website News Releases the original release is there. The story is more about access to tests for poorer nations.
GLA
R
Daily Mail today - Antigen test that gives result in 15 minutes to rolled out across the world.
https://www.dailymail.co.uk/news/article-8783491/On-spot-coronavirus-tests-results-15-30-minutes-set-rolled-out.html
Does the mass spectrum give away any commercial ip of the chemicals used? Any thoughts?
Test, test, test
Monkshood, looking at the mass spectrum, m/z scale went up to several thousand. Would this infer a magnetic sector mass spectrometer as opposed to a TOF mass spectromer being used?
Test, test, test
The migration through the LFT would, I guess, change with the degree of glycosylation as it will affect the polarity of the protein however I (also guess) that they will still all be caught at the test line.
Buffer modification may help counter some of the differences between high/low glycosylation.
I was curious what the impact was -hence the question...
I too would like know what the LOQ of the BAMS is - I think we will find this out fairly soon, they clearly think it is low enough to be viable as an effective test.
One other query on BAMS...
The slide says about the BAMS test, 'exquisite specificity' and, seeing how detailed the mass spectrum plot is, one can see that it would be exquisitely specific, as required for keeping the false positives low, which people recently have been saying is such a problem for low prevalence. One detail that is missing from the BAMS slide , though, is just how much SARS-CoV2 there was on that one bead?? Any thoughts?
Test, test, test
Question for the Chemists here
One potential loose end, which came up in the questions, is the extent to which Glycosylation affects the LFT: Dr AS treated this as an interesting technical detail to find out about.
However, it is a different question to whether the Affimers bind to spike proteins with different degrees of Glycosylation, which he did answer clearly as not being a problem - the issue is how the LFT behaves with different degrees of Glycosylation.
Any thoughts??
Test, test, test
Sorry Enteleon, not sure what you mean about 'c surface protein' , however as they have not said exactly where the Affimer(s) bind it is hard to put their use, as a blocking agent for example, into context.
Nixynoo, the results look fine but hard to tell without further details, I was interested if they used digests as it is another step in the sample processing.
So now we know who asked the question about glycosylation!
Do you think the results looked positive? Was a completely meaningless slide to any layperson, but would be good to know if what AS made sense to someone who comprehends!
Monkshood: superb elucidation of the chemistry, thank so much. I was burning to ask a question about the "C surface-protein", which is apparently important in the confirmation of "infectious" status, as differentiated from other Covid-19 statuses (alluded to by Sir John Bell).
I was very disappointed that I could not discern any reference to this C surface protein in AS' answers. I had imagined that one reason for delay may have been the realignment of Affimers to latch on to this protein, but apparently not.
With your great expertise, can you kindly help us out here, please?
Did you listen to the Q&A? I confess that I don’t understand your post, but I do remember a positive response to a question about glycosylation at the end of the session.
Looking at the data for the BAMS assay in the talk, the schematic is rather simplified. They have clearly done an on-bead digestion prior to the MS, but having spent all afternoon on it I have still not worked out what with, I cannot get the peptide fragments to map to the usual enzymes. (FYI -the numbers to 3 decimal places are the m/z and the range below will be the amino acid position of the peptide. The peptides will typically be singly charged [+H] but they can for adducts with salts such as Na+ and have other modifications).
I was also curious to know if they also de-gylcosylated the samples first but until I can work out the digestion method used this is hard to determine.
Looking at the peptide sequence and their profile I am not sure that they will be able to see the D614G mutation – it will depend on the digestion method used, but was not obvious in the profile, note -the point that was made in todays talk, was that it did not affect binding, not that it could be specifically detected.
The S1 protein is a highly glycosylated protein so it was nice to have it confirmed that the binding of the S1 Affimer(s) is not affected by the glycosylation state, I had been concerned about this but assumed it was not a problem after the ELISA results were released. The ELISA is a sandwich method so they must also have a second Affimer binding site that they utilise. Often methods are developed using a protein expressed in E.coli which will not have the same ‘decoration’ of sugars as the protein in saliva samples which is why this was important, if the site the Affimer bound could be glycosylated then it may not bind reliably for all samples, as the level of glycosylation can vary. I am not sure that they would have had the information about this at the start, but they have now used the BAMS to work out exactly where the Affimer(s) bind.