The world of COVID-19 testing and our understanding of the virus has caused many of us to read science and health articles laden with new terminology that may be challenging to understand. One of the areas of knowledge that is difficult to understand is COVID-19 testing. Let’s take a closer look at some of the work presently being done.
When it comes to viruses and the diseases they cause, there are two basic types of testing. One, testing to see if the person being tested has virus in their system; and two, testing to see if the person has developed antibodies against the virus. We will look at each in turn with regard to the COVID-19 disease and the SARS-CoV-2 virus which causes the disease.
Virus testing in this first case, is done almost exclusively by reverse transcription polymerase chain reaction (RT-PCR). This is the recommended initial test to see if a person is carrying the SARS-CoV-2 virus in the deep parts of the nasal passages. This test detects the rna of the actual virus by transcribing its rna into DNA and amplifying the DNA (making more of the DNA). This is a highly sensitive test and is capable of detecting as few as one virus particle. The test relies on the concept that if a virus particle is detected deep in the sinus cavity of the patient, the patient’s body is likely manufacturing the virus particles in the cells of their respiratory system and shedding them out into the world around them through moisture in their breath. This article will not assess the tests but rather describe the tests (some of the readers of this article may already be seeing the pros and cons of this testing method). Spartan Bioscience in Ottawa has just received approval to sell their rapid detection kit to the Canadian market. It is exciting to see this new made-in-Canada solution to testing for SARS-CoV-2.
In the second type of testing, the clinicians initiating the test are looking for antibodies against the virus. Normally, when our bodies are introduced to a new virus in our cells, our immune system goes through a system of activation and biochemical cascades which result in the production of antibodies against the novel virus. These antibodies are part of a healthy person’s biological response to a virus and the beginnings of how we fight off this new challenge to the integrity of our cells. We want our cells to exclusively make proteins for our own use and we do not want them making more viral rna or viral proteins. Therefore, our immune system must initiate its own biological warfare against the invading army of viruses. Antibody testing relies upon this ability of the body to make antibodies against a foreign particle in our system. If our body has experienced the new virus and has had sufficient time to mount a response, there will be antibodies in our blood to indicate that this has happened. Antibodies such as this may last for a matter of months or many years. Thus, one can test for specific antibodies against SARS-CoV-2 while the person is in an active COVID-19 disease state or even after they have recovered. This type of testing may be invaluable in determining who has survived the disease and may possibly be a source of antibodies that could potentially be transferred to another person to give them immunity to the disease.
This second type of testing is more of a classical immunological test. A molecule capable of binding to the antibody, something that bears a resemblance to the binding portion of the viral particle, is bound onto a substrate (perhaps a paper inside a testing cassette) and then a blood sample is placed in contact with the detection molecule. After an appropriate wash, to cleanse the cassette of any unbound particles, the one performing the test looks for evidence of bound antibodies. This is most often a colour change on the substrate (think of how an early pregnancy detection stick works) to indicate the presence of the antibody against the virus. (Again, there are pros and cons of such a testing regime, but for now, we will forgo any assessments.) Tests such as this are in development in Canada as well. The test manufactured by BTNX is approved for sale in the US and UK but is not yet approved for the Canadian market. This type of testing will be critical to further research and for such important tasks as testing donor blood at Canadian Blood Services. We can applaud such active and rapid research into both of these areas of testing.
Post a comment or send an email if this article has created further questions. I will do my best to research the questions and provide answers.
The virus itself is a simple little biological entity, less alive and more
machine-like. It consists of only 30,000 base-pairs of rna and just a few proteins. Perhaps I will write more on that later.
This virus is also sometimes referred to as “the coronavirus” (but of course it is simply one of many coronaviruses) or the 2019 novel coronavirus or 2019 nCoV.
”Coronavirus Disease 2019 (COVID-19).” Centers for Disease Control
and Prevention. 2020-03-21. Retrieved 28 March 2020.
For that is what virus particles do, they get inside a host cell and use the
cell’s machinery to make more virus particles.
Notice I avoided saying, “by speaking moistly.” This is out of respect for our
Prime Minister and the great job he is doing each day keeping the Canadian public informed. It is so easy to stumble over one’s words in such settings. We all need to give him a break.
“Everyone wants them: Rapid COVID-19 test kits made in Canada approved for use,” CBC News, 2020-04-13, https://www.cbc.ca/news/canada/ottawa/spartan-covid19-test-kit-new-1.5530669.
People who are immune-compromised for various reasons may not be fully capable of mounting such an immune response against the virus.
I am intentionally using a number of conditional words and clauses here. The research has not yet shown whether or not it might be possible to transfer immunity via this method. But, it is a hopeful plan.
“Health Canada says rapid blood test for COVID-19 remains under review,” CBC News, 2020-04-12, https://www.cbc.ca/news/health/health-canada-rapid-blood-tests-under-review-1.5529590