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Dryland, I am not from bio background and this is my understanding: COVID virus enters human cells using spike protein to bind the external shell layer at the initial stage. The fact that Affimers bind both intact virus particle and detached protein spikes allows the detection of virus even at the very initial stage (first few days without symptoms) at a low viral percentage.
LiveLong,
This question was raised before but remains unanswered. PCR test is the golden standard for the reason that it could detect only one molecule, and nasal/throat swap is used because that is the place where virus mostly likely to be. My worry is that the viral load in saliva won't be as high to trigger Afimmer binding reaction. There are a few experts like VanV, MrSpaceTomota, ab??, wBernard etc on this BB and had a heated discussion: findings are the viral load requirement was mentioned in the academic sources on animal studies but not from clinic trial. I also hope some experts could chip in the discussion and answer this.
The CEO has addressed the specificity issue on webnar. The Affimer LFD will likely not to cross react with other cronaviruse. The sensitivity remain unknown, or I might have missed that part. The common issue faced by many other antigen LFD tests is the sensitivity issue - false negatives caused by low viral load. I have tried to find the minimum required viral load to trigger the Affimer reaction from Zoe's thesis but couldn't find any. I hope Avacta could tackle this issue, because this appears the industry hurdle at the moment for LFD, which is the key to the success of the antigen test.
Another source mentioned one test might cost as little as $1?
"Another company, Mologic in the United Kingdom, is developing an antigen test and hopes to get it approved by June, according to Fionna Tod, a company spokeswoman. The test would produce results in 10 minutes and would sell for about $1, she says, which could be very helpful in less affluent parts of the world."
I dont think the test will cost that much. I found this:
"According to Gehrke, the covid-19 tests were developed from the same basic platform used to test for Dengue and Zika. Those tests were 90 to 95% accurate, and he expects the same for the covid-19 versions. He says each test should cost as little as $10; a PCR test runs more than five times as much. The company expects that when production is under way, it should be able to produce millions of these tests regularly."
So tener per test might be a reasonable guess?
Following previous email:
"With the limited data now available, WHO does not currently recommend the use of antigen-detecting rapid diagnostic tests for patient care, although research into their performance and potential diagnostic utility is highly encouraged." Suppose we pass the sensitivity hurdle, our test will fly off shelf in no time.
Another interesting read from MIT technology review:
"Gehrke is a cofounder of a Cambridge-based biotech company called E25Bio, which is developing a covid-19 antigen test. Like most others being developed for the coronavirus, the test works by taking a nasal swab from a patient and introducing that sample into a solution that is then exposed to one end of a series of paper strips. The strips contain artificial antibodies specially designed to bind to coronavirus antigens. As the solution moves up the strip, any antigens that are present will bind to it and give a visual readout. The whole thing takes less than 30 minutes, and it doesn’t require special equipment or training. ". They claimed that their accuracy rate is 90%, but still awaited validation. They sensitivity rates mentioned by WHO on LFT of influenza is 34%-80%, as long as we can pass this, we will be in better hands.
This question has been raised many times and my answer to this is "very promising". I found the following refererencing in Zoe's PhD thesis back in 2017 (concerns have been expressed on cross-reactivity, and also sensitivity to low viral loads, but I think this issue should have been tackled after 3 years:
"Affimers can be used as replacements for antibodies in basic LFDs, for the direct detection of a viral protein, in this case the swine virus PRRSV N protein as the detection antigen. Compared to antibodies, Affimers are cheaper and easier to produce and remove the requirement of animals in the production process, making them a desirable alternative reagent for this purpose. The findings suggest that Affimers are indeed strong candidates for antibody alternatives in LFDs.
The nature of the Affimer reagents, specificity for the target protein, meant that the Affimer-antibody assay was able to distinguish between the carcinoma it had been produced to detect whilst eliminating other liver diseases from the diagnosis. The improvement of sensitivity was increased by 36- 65% in the dual antibody assay to 62.5% in the combination assay while specificity was shown to be improved to 92.3% from a range of between 55-100% in the dual assay (Xie et al., 2017). The increase in specificity and sensitivity is likely due to the greater sensitivity of the Affimers to the target antigen compared to the antibody counterpart as a result of the initial screening process carried out to identify suitable Affimer reagents.
The production process of Affimers can also overcome the difficulty of mutagenic viruses and viruses with homologous proteins. RNA viruses like PRRSV are highly mutagenic and so it is not guaranteed that the reagents (Affimers or antibodies or DNA or RNA aptamers) used in diagnostic tests will always identify the proteins of interest during a prolonged outbreak. If a mutation occurs during an outbreak at the epitope of the protein where the reagent binds the test becomes redundant. The production of Affimer based LFDs can also be 180 easily modified to detect a number of viral antigens giving increased sensitivity and the reduction in false positive or false negative results. A multiplex system can also be employed to include a number of Affimers binding to different epitopes of one protein as it is unlikely that a mutation would occur at the covered epitopes at the same time, hence prolonging the life of the device during an outbreak."
The antigen test has been mentioned and encouraged by WHO as well:
"If any of the antigen detection tests that are under development or commercialized demonstrate adequate performance, they could potentially be used as triage tests to rapidly identify patients who are very likely to have COVID-19, reducing or eliminating the need for expensive molecular confirmatory testing.With the limited data now available, WHO does not currently recommend the use of antigen-detecting rapid diagnostic tests for patient car
As pointed out by many other posters, although similar price-wis and working with Cytiva, these two companies are rather different in many ways :
1. Business nature: AVCT's main game is in Cancer research and Affimer or antibody business. The test is only a side-line utilizing the Affimer technology. GDR's main game is in Antigen test and their portable test machines. Please correct me if I am wrong.
2. Company shares and potential growth. AVCT has over 200mil shares whereas GDR only 30mil. This will reflect on the share price movement and future expansion. There are pros and cons along with this. The financial aspects from two companies also differ: revenues, earnings, and cash flow.
3. Their COVID testing business has different market catchment. AVCT 's test can be used in a more "retail" way and accessible by everyone. GDR's test is a portable PCR test that works best for "institutions". Both will have very different market shares.
I think if you look at the general picture of how to free the lockdown and the test offered by Avacta, you will find the answer. Avacta is also not a one-trick pony. Please have a look of the research done by Myles McNulty and you will find the answer.
It is an antibody test, which is almost what every lab is doing.
King, I remembered some discussion about the possibility of them three working together, but as you pointed out, sona and avacta might be not compatible.
I think they don't need to be, 90% will do to be pushed into the market.
IMHO the pie is big enough for everyone, as another poster pointed out, the emergence of MRI didn't terminate the use of CT scan. One thing clear is that the successful test strip by AVCT will limit the growth potential for NCYT. These are just two shares fitting different risk-return appetites.
Alexa, I suggest you read the original report by Myles or another analysis report by Hardman & Co on Avacta. A quick comparative search will lead you to this company, which is among another few company in the same business. Sona has been in the same game as Avacta, and their test kit progress is about a few month ahead. We should acknowledge the potential competitions but also be aware of our strength: cheaper and cost effective.
Luke, very informative video. We face similar validation challenge which is the accuracy hurdle. I hope the other posters could have a look and comment on it.
This is also why NCYT is £3-£4 and AVCT is £1. The uncertainty is factored in the price. As holders of AVCT we are investing the potential growth of this company which could be astronomical.
I don't think it is fair to compare the AVCT LFT with other strip test like pregnancy test, as their functions vary by miles. It is fair to compare the price with similar test provided by Sona Nanotech, which is designed for the same purpose using the same platform. The Sona's test IMHO was designed using antibody provided by the Native Antigen company, and this is why it is so expensive ranging $40-$50. The antibodies are more difficult to produce and duplicate. The AVCT's test would be either half or a third of this price, as Affimer proteins are cheaper and easier to produce.
The link was removed by the board. Please search "Coronavirus and the Need To Go Beyond Testing in a Pandemic"
A quick google search: https://www.technologynetworks.com/diagnostics/blog/coronavirus-and-the-need-to-go-beyond-testing-in-a-pandemic-333283
Quote: "This novel test is based on lateral flow technology and will be able to detect the virus even in small quantities in seemingly healthy people who are showing no symptoms. Giving results in 5-15 minutes, this rapid test will cost less than US $50 when ready"
But their test may just based on the utilization of antibody, which is more costly. The Affimer abased test is more cost effective, and will be a lot cheaper than theirs.