Brian Harry, MD, Assistant Professor of Pathology and Medical Director of Special Chemistry at the University of Colorado School of Medicine and Ashley Frazer-Abel, PhD, Assistant Research Professor, Medicine-Rheumatology at University of Colorado School of Medicine and Director of Exsera BioLabs talks about their team’s effort to build a “homegrown” COVID-19 Antibody test.
Brian Harry, MD
Tell me what your part is in this homegrown antibody test.
Dr. Harry: The Clinical Laboratory knew this spring that it needed to develop molecular testing and serology testing for antibodies against SARSCoV-2, which causes COVID-19. So, in March we started these efforts. At that time, it was really unclear where the tests were going to be coming from, what the quality of the tests would be, and what the laboratory supply chain would look like in terms of the ability to access those tests if there’s a global pandemic. Because not only are people trying to build tests in areas that are affected, but there are a lot of areas that need to deploy testing. So, we were overly concerned about our ability to access high-quality testing, and this group came together to design our own serology antibody testing for the virus. That way we could have a clear view of what the quality and performance of that test would be.
What makes this test special?
Brian Harry: One of the things that makes it special is we are testing for two different proteins in the virus. So, when your body mounts an immune response, it produces antibodies against proteins that are expressed by foreign invaders. We are testing for antibodies against two separate proteins from the SARSCoV-2 virus. So that gives us an additional layer of information and added layer of reassurance if both of those are there. You likely saw the SARSCoV-2 virus because there is concern that there could be cross-reactivity for antibodies against other coronaviruses. So, if you had a common cold this past winter, we do not want to think that you previously had COVID-19. So, we want to be able to discriminate between those two.
The first antibody tests that came out were about 50% accurate, correct?
Dr. Harry: There were several that had major concerns. Spain had deployed testing that had incredibly low accuracy and sensitivity rates. The U.K. spent thousands to millions of dollars on testing that ultimately was found to not be adequate to deploy broadly. So, there were enough stories out there where we knew we could get in a situation where we were offering Coloradans subpar-quality testing if we were not careful. Since then commercial companies have developed incredibly good tests. The ones that we brought in house at the University of Colorado Hospital are exceptionally good and the tests that we built at the University of Colorado Anschutz Medical Campus have performed just as well, if not better than those tests, but it also gives us that added layer of information about both proteins.
So why is having that added layer of information so important?
Dr. Harry: All the tests that we offer at the University of Colorado have a specificity above 99%. The test that we developed in Dr. Frazer-Abel’s lab at the University of Colorado has the specificity of 99.6%. What that means is, if we test 1,000 Coloradans who we know have not had COVID-19, only four out of those thousand will be false positives indicating when that individual gets the test, they think they have had the disease at some point. So that is scary for those four individuals, but from a test standpoint it is an exceptionally good performance. So, we are looking for greater than 99% specificity, and the closer to 100 we get, the better because we do not want to falsely identify individuals as having had COVID-19.
That is a concern for a lot of people right now.
Dr. Harry: Yeah and I think we are starting to communicate more broadly across the University of Colorado health system about the quality of the tests that we have, and I think that information has reached most of our frontline providers. So, at least at the UC health system and University of Colorado, if you see your physician and you are getting an antibody test or you’re getting a molecular test, we know that the quality of those tests are very good. I can speak on behalf of those organizations to say they are the best that exist on the market or that exist in terms of how they have been built, such as in Dr. Frazer-Abel’s lab.
You are in clinical trials right now, right?
Dr. Harry: No, we have done test validation, which means we have tested known samples from negative patients before SARSCoV-2 existed in humans. We have also tested samples from patients who had COVID-19 this past spring. So, by having those sample sets, we can essentially test the performance of that assay. Using that is where we get a sensitivity greater than 80%, meaning that at least 80% of cases will be identified as positive if somebody has had the disease and more than 99% of cases will be identified as negative if somebody has not had the disease.
This test is going to help in the creation of a vaccine, correct?
Dr. Harry: Yeah. The way most vaccines work is they ultimately enable expression of a protein that is considered immunogenic. So, the purpose of a vaccine is to stimulate the body to generate an immune response. We do this with hepatitis B, we do this with many other viruses and bacteria to provide immunity to individuals through vaccination programs. So, the vaccination efforts right now for COVID-19 are going to express proteins from that virus to induce an immune response and we will be able to capture vaccines that are trying to stimulate antibodies against either of the proteins that we’re using. In addition, if one type of vaccine gets adopted that focuses on one protein we may be able to distinguish between people who get vaccinated versus people who have had natural immunity due to exposure and infection with SARS-CoV-2. We do not know for sure if that is the case, but that is one of the possibilities that comes out of performing a dual antigen test.
Through this work, have you been able to answer questions that have not been answered about the coronavirus?
Dr. Harry: I would say that we have learned a lot and our group has learned a lot. Many of us are not coronavirus experts or even virologists, but what we do know is how to generate very high-quality testing. One of the things that our group has learned is that the rate of common coronavirus infection is quite high. In our pre-pandemic samples collected before COVID-19 existed, most of the individuals had antibodies to a common coronavirus. So that was something that we discovered. There was a report this week out of China saying the antibodies from COVID-19 patients may not last that long and that on average they may only last two months. So, the question around the immunity is how strong the antibodies against the virus are and how long do those antibodies last in individuals. They remain open questions, but data is starting to trickle in about what that may mean.
So, it has been a great experience for you because you have come together as a team?
Dr. Harry: The University of Colorado Anschutz Medical Campus has a serology working group focused on the development of antibody testing. So there are epidemiologists, virologists, biostatisticians, rheumatologists, clinical immunologists, clinical pathologists – all types of experts who have some piece to contribute either because they understand the virus, they understand the immune response or they understand how to develop good testing. This group is what was necessary to make this test homegrown. We had people growing viral proteins, and we had Dr. Frazier-Abel in her lab deploying the testing, putting the proteins on a plate and testing samples to understand how we can improve this assay. It is really the joint expertise that has enabled the development of this test and the strong collaborative relationships among our colleagues.
Do you think this test will be available in other places?
Dr. Harry: I hope there will be strong academic collaborations where we can use this test to ask more focused questions. I think that one of the main drivers when we developed this was to make sure that testing was accessible to Coloradans. If you think about the millions of Coloradans over the next several years if COVID-19 stays with us we want to make sure they have access to quality testing. Even if we do not fully understand what it means right now, we want to make sure when it enters a clinical scenario, we have it offered. We want to make sure when vaccines are available, that it’s here and available and we want to make sure that people who are concerned about having had the virus or are curious about whether they have it have access to a test that will give them a very accurate result.
So, you do not need a clinical trial for this?
Dr. Harry: No, what we need is extraordinarily strong data so we can say this test is high quality. When we start rolling out the testing, we can submit that to the FDA and say to them, look at what we have done, what do you think? And since we know the tests that have already been approved, we are extremely confident that this test will be looked upon equally well by the FDA.
Ashley Frazer-Abel, PhD
What is an antibody?
Ashley Frazer-Abel: An antibody is a protein part of your immune system that reacts against an infection once it is learned. The innate part of the immune system, which is what I originally studied, gets things started, kind of orchestrates the process. But then once your immune cells are geared and started on the infection, they are going to produce the antibodies against it. And that is when you are going to be able to fight the infection and clear it most effectively. It is also what we use in the lab to tell that you have had the infection. In this case you are going to have specific antibodies to SARS-CoV-2 that we can detect. They help you fight the infection and then we can use that as a tool in the lab. So, why do some people have that antibody, and some do not? There is the obvious that if you have not been exposed to SAR-CoV-2 then you do not have the antibodies. There also seems to be an element of people who are responding the same way because they have a deficient immune system and it looks like they are not mounting a strong infection and not sick enough to get hospitalized. Your body’s not producing the antibodies in the same level. We are still figuring that out why that is different. But it does seem that some people, even though their immune system appears to be completely normal, are not mounting the same amount of immune response. So, we are not detecting that, but it does seem to be relative to how strong your disease was. If you are hospitalized or you are in the ICU, you are probably going to come out with antibodies. If you are someone who can convalesce at home, you may not show up with antibodies.
It is now going around Facebook that you can get the antibodies or have COVID and end up with the antibodies. Then within a couple of months those antibodies go away. Is that true?
Ashley Frazer-Abel: There is a recent paper out of China that is looking at that question and we are still working to understand how long the antibodies will last. Right now, there is some evidence that it is only going to be a matter of months versus years. With SARS, the first SARS and MERS, which are very related those antibodies lasted well over a year and two years. It looks like SARS-CoV-2 will be shorter. That does not mean that everything is done. Because what we can detect in the lab and what you can protect in your body may be different. There is some evidence that in months we will not be able to detect them but that there might still be immunity. These are all questions we do not know the answer to yet. The testing we are doing is going to help answer those questions. But we do not know how long they last, and we do not know yet how good the immunity is from it.
So, what makes your research different?
Ashley Frazer-Abel: What makes us one of a kind is we are doing a dual antigen. We are looking at two responses to the SARS-CoV-2. RBD, which is part of the spike protein, which is on the outside of the virus and nuclear capsule which is inside. By doing this, we are measuring you twice and fulfilling one of the CDC requirements. With the rate that we all have of infection right now, a positive result may be a false positive. So, we need that second result to see if it is truly positive. Most assays are going to have to go out there and get two. If you are asymptomatic and you get one positive antibody response, you are going to have to go and get another one to fulfill the CDC requirement. Our assay does it once, and it does it for two different parts of the virus. There’s good information that may tell us something different about your response. Whether you respond to the nuclear capsule or the spike protein differently and it has the potential to get to the point where the vaccines are extremely helpful. So depending on whether your vaccine is to the spike protein, which most of them are, we’re going to be able to tell whether that response was from the vaccine or from an earlier infection whereas the other assays will be able to differentiate it that way. The other thing that makes ours different is its supply chain independent. By using the expertise on this campus, we are producing proteins and making assays here. So, we do not have to compete against New York to get the kits. We do not have to compete against Germany to be able to do the assay. We can do the assay just with the expertise and the reagents that we can build, which is immensely powerful should we get to a point where supply chain and supplies are short, but we still need tests.
How long did it take to run the tests?
Ashley Frazer-Abel: It is a matter of a couple hours. Of course, you must get through all the other processes to track everything. It is not a 15-minute minute test, but it is a matter of hours.
And is it currently being tested?
Ashley Frazer-Abel: Yes, we are starting the testing right now. We are released and are putting in the emergency use authorization. But we are currently running clinical samples.
How is the testing done?
Ashley Frazer-Abel: The testing is done in my laboratory. It is an automated instrument. So, with these little 96 well plates we can have each well doing a different sample. It is commonly used for a lot of other methods. But we have really specialized it for SARS-CoV-2, and they made it a little more unique. I never thought venous puncture, or a blood draw would be the easier option. But it is just a blood draw to get the sample. There is none of the tickling your brain with a nasal swab that you must do for the molecular test.
You know, everything is about getting things done fast. Do you think this will get through faster?
Ashley Frazer-Abel: Because we are supply chain independent, we do not have any of those things getting in the way of our assay and our result. It is a matter of something that is only a couple hours and we can do a lot of them at once because it is automated. I really think we are looking at something that can be very quick to get an answer. Then what to do with that answer is a whole other question. But we do not know that unless we start asking the question within a test.
Is it something that other places could pick up?
Ashley Frazer-Abel: So initially we based ours on the work out of Mt. Sinai and then we went past that. And I think part of the reason we did it the way we did is it could be scaled, transferred out and built upon by other groups if that becomes something that is necessary or useful.
What are the three big questions out there about your testing?
Ashley Frazer-Abel: The biggest one is does it give us immunity and then if we have that immunity, how long will it last? There’s good information now that it looks like we may be a yes to the first one. We really hope so because that is going to be key to a vaccine and everything else. How long will it last? That is a good question because that makes a difference in how long the vaccine will last. And then one questions I get that is a curiosity question. I think so many people are interested in the antibody testing just so they can know whether that bad cold they had in February was the SARS-CoV-2 and if they already had it or not. I think in some ways that might not be a scientific question, but I know everyone is really kind of thinking that themselves.
Will your testing provide those answers?
Ashley Frazer-Abel: It could very much answer a lot of those questions and using it also gives us that denominator. We all want to know what the rate of spread is. We all want to know how many people have already had it. We cannot answer those questions unless we can add to the antibody test. This molecular test is only the people who are sick, not the people who can convalesce at home, not the people who are asymptomatic. So, we need that antibody test to know the denominator, to know what the infectious rate is and so on.
What is it like to separate from life and be stuck in the middle of the pandemic research?
Ashley Frazer-Abel: I am not sure that I knew what I was getting into when I was in the immunology lab and asked can you step in here, can you help. Of course, I said yes. Why would you want to be in the middle of this if you could not step up and help? So, it does feel good to be moving forward instead of just waiting. But it is also a heavy responsibility and something that we feel very strongly about. Every member of my team that I have asked to be part of it has been very enthusiastic to be moving towards a solution instead of just waiting for others to do it. The other thing why it has been interesting for me to be part of and something that has been very heartening it is the kind of science I have always wanted to do. It ended up being an ad hoc team. We have an extraordinarily strong virologist, Tem Morrison on the project and we have Dana Aisner working on it. We have scientists across the campus that came together regardless of their specialty and brought their expertise to it to make this assay something that none of us would have been able to do on our own. But together we did it and we did it faster than I have ever seen such an assay come to life. So that’s the kind of science that really propel things forward and it was really quite the opportunity to be a part of that.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
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