Understanding Testing

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[1]
which causes the disease.[2]

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.[3]
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[4]
and shedding them out into the world around them through moisture in their breath.[5]
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.[6]
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.[7]
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.[8]

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.[9]
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.