Biology of SARS-CoV-2

Explain how the terms COVID-19, SARS-CoV-2, and coronavirus mean different things.

• Coronavirus: Family of viruses that includes SARS-CoV-2 • SARS-CoV-2: Means Severe Acute Respiratory Syndrome and Coronavirus 2. This is the virus that causes COVID-19. • COVID-19: Disease caused by SARS-CoV-2

Antigen test

- Tests for presence of pieces of viral proteins (antigens) - Accuracy: More false negatives than the RT-PCR tests. May need other tests to confirm negative results. - Time to get results: one hour or less

RT-PCR test

- Tests for the presence of pieces of the virus's RNA genome - Accuracy: Few false negatives. Test usually does not need to be repeated. - Time to get results: one day to one week

The SARS-CoV-2 virus has an RNA genome made of 30,000 nucleotides. List four of its nucleotides.

1. A- Adenine 2. U- Uracil 3. C- Cytosine 4. G- Guanine

In addition to the tests describes above, people can also get tested for the presence of SARS-CoV-2 antibodies. Explain how an individual could test negative for an active SARS-CoV-2 infection and positive for SARS-CoV-2 antibodies.

An individual could test negative for an active SARS-CoV-2 infection and test positive for SARS-CoV-2 antibodies because they had the virus in the past, but are not currently infected with an active virus. An antibody test is different from an RT-PCR test and Antigen test because the antibody test detects for specific types of antibodies. Antibodies are proteins that the body produces after it's been infected with a virus, such as SARS-CoV-2, that detect the presence of the virus if it returns in the host cell again. This recognition of these antibodies helps our bodies fight the infection. These antibodies are not active virus cells, so a person could test negative for an active SARS-CoV-2 infection and positive for the SARS-CoV-2 antibodies.

In addition to the tests describes, people can also get tested for the presence of SARS-CoV-2 antibodies. Explain how an individual could test negative for an active SARS-CoV-2 infection and positive for SARS-CoV-2 antibodies.

An individual could test negative for an active SARS-CoV-2 infection and test positive for SARS-CoV-2 antibodies because they had the virus in the past, but are not currently infected with an active virus. An antibody test is different from an RT-PCR test and Antigen test because the antibody test detects for specific types of antibodies. Antibodies are proteins that the body produces after it's been infected with a virus, such as SARS-CoV-2, that detect the presence of the virus if it returns in the host cell again. This recognition of these antibodies helps our bodies fight the infection. These antibodies are not active virus cells, so a person could test negative for an active SARS-CoV-2 infection and positive for the SARS-CoV-2 antibodies.

Each of the following statements describes a step in the replication of SARS-CoV-2. These steps are listed in random order. List the steps in order. A. The virus releases its RNA into the cell B. Viral genome polymerase helps transcribe more copies of the viruses RNA. C. The virus binds to a receptor on a human cells membrane. D. New viruses travel to the cell membrane of the infected cell and are released outside the cell. E. The viruses RNA is translated into protein by the cells ribosomes.

C, A, E, B, D

Crown (corona) of protein spikes

Protein spikes attach to specific proteins on the surface of the cells in our bodies. This causes the viruses membrane to fuse with the cells membrane releasing the viruses RNA genome into the cell.

Studies have shown that SARS-CoV-2 has a slower mutation rate than the influenza virus, which causes the flu. This means that mutation occurs less frequently in SARS-CoV-2's genome than in the influenza viruses genome.

SARS -CoV-2's genomes have a slower mutation rate compared to the influenza viruses genomes that have mutations which occur more often. Since less mutations occur with SARS-CoV-2 genome, this means that it will be less likely for the vaccine to have a need to be modified as often because the mutations that we see now are most likely going to be the same mutations we see in the future. As long as these mutations are still present and no new mutations are created and spread rapidly the SARS-CoV-2 vaccine should not have a need to be modified as often as the flu vaccine. The flu virus mutates at a faster rate, so modifications need to be done to the vaccine more frequently in order to ensure humans cells recognize these new mutations and can protect our bodies against them. This is why the flu vaccine is administered yearly, so our bodies can build immunity against the new mutations of the virus.

How could sequencing many SARS-CoV-2 genomes be used to track how the virus has changes over time due to mutations?

Sequencing many SARS-CoV-2 genomes can be used to track how the virus has changed over time due to mutations because scientists are able to compare these mutations and determine their origin, how they spread, and how harmful they are to the human body. This helps scientists develop effective vaccines and treatments that fight against these mutations.

Scientists discovered that SARS-CoV-2 is 10 to 20 times more likely to bind to the receptor that any other coronavirus was. Predict how this increased chance of binding has affected SARS-CoV-2's ability to replicate.

Since SARS-CoV-2's ability to bind to the receptors on our cells surface has increased this affects the viruses ability to replicate because the spikes on the virus recognize our cells faster and immediately bind to them. This makes it easier for the virus to spread faster from person to person infecting each of our host cells easily. The protein spikes attach to our cells, the viral membrane and cell membrane fuse together, and the viral genes enter the host cell to be transcribed and produce more viral genomes.

Viral genome (RNA)

The Viral genome (RNA) is released into the cell that it attaches to in the body. Then the viral genome is translated into proteins by the cells ribosomes, including viral RNA polymerase. The RNA polymerase transcribes the viruses viral RNA, making more RNA copies that are translated into proteins. Viral genome (RNA) is also copied, and the genome combines with proteins to make a new virus that is packed into an envelope formed by the cells membranes. The newly formed viruses are then sent outside of the cells surface where they can either leave the body and infect others or infect other cells in our body.

Envelope

The envelope allows the protein spikes to attach to other cells surface and infect the host cell. The envelope also protects the viruses viral genome (RNA).

As shown in the animation, sARS-CoV-2 uses the ribosomes inside human cells to translate its RNA into viral proteins. According to the animation, what is one of the viral proteins made by the ribosomes, and how does that protein help SARS-CoV-2 make more copies of itself?

The viral protein that is produced by ribosomes inside human cells during the translation process is RNA polymerase. RNA polymerase assists SARS-CoV-2 by transcribing the viruses RNA to generate more copies of itself. These copies are then translated into proteins. New copies of the viruses genome are created, and these new copies of the viruses genome and proteins combine with one another to create a new virus. This new virus can either infect more cells in our bodies or it can travel out through the nose or mouth and infect others with the virus.