14 E3

Question 1

What is remdesivir?

Answer 1

The first antiviral drug approved for COVID-19 by the US FDA in October 2020

Remdesivir is a nucleoside analogue that resembles RNA building blocks.

Question 2

How do nucleoside analogues work?

Answer 2

They mimic the structures of nucleosides, getting incorporated into RNA strands and halting RNA polymerase activity

This prevents the virus from making copies of itself.

Question 3

What is RNA polymerase?

Answer 3

An enzyme that viruses use to copy their RNA

It acts as a molecular copier to produce additional RNA strands.

Question 4

What structural feature of remdesivir is similar to adenosine?

Answer 4

The two nitrogens in the top right of the molecule

This allows remdesivir to form hydrogen bonds to uridine.

Question 5

What is the effect of the cyanide group in remdesivir?

Answer 5

It distorts the RNA strand, stopping RNA polymerase after adding three more nucleosides

This halts the completion of the copied RNA strand.

Question 6

What is unique about molnupiravir’s active form?

Answer 6

It has two forms, or tautomers, that can switch between each other

One form mimics uridine and the other mimics cytidine.

Question 7

How does molnupiravir confuse RNA polymerase?

Answer 7

By appearing as two different nucleosides, it introduces copying errors in RNA replication

This leads to the virus’s demise.

Question 8

What stance has the World Health Organisation taken on remdesivir?

Answer 8

They have stated there is insufficient evidence for its effectiveness against SARS-CoV-2

Since November 2020, they have recommended against its use.

Question 9

What is currently being developed related to remdesivir?

Answer 9

A pill version that may be effective in earlier stages of the disease

This could improve treatment options for COVID-19.

Question 10

What positive results have been seen with molnupiravir in clinical trials?

Answer 10

It appears to reduce the risk of hospitalisation and death from COVID-19

Several countries have preemptively ordered the drug.

Question 11

What concerns have been raised about molnupiravir?

Answer 11

Some safety concerns and the need for published safety data

It has passed phase 1 safety trials.

Question 12

What type of drugs, besides nucleoside analogues, are being developed for COVID-19 treatment?

Answer 12

Protease inhibitor drugs

They bind to the viral protease enzyme to prevent viral replication.

Question 13

What does ELISA stand for?

Answer 13

Enzyme Linked Immunosorbent Assay

ELISA is used to detect antibodies or specific antigens.

Question 14

What is the purpose of the direct ELISA?

Answer 14

To test for the presence of antigen

In direct ELISA, a known antibody is absorbed to the well and interacts with the antigen.

Question 15

Describe the process of the direct ELISA.

Answer 15

1. Absorb known antibody to well
2. Add sample containing antigen
3. Add enzyme-linked antibody
4. Add colorless substrate
5. Development of color indicates presence of antigen

Question 16

What indicates the presence of the antigen in a direct ELISA?

Answer 16

Development of color

The enzyme-linked antibody binds to the antigen if present.

Question 17

What is the primary function of the indirect ELISA?

Answer 17

To identify the presence of antibodies

Indirect ELISA involves adding antigen to the well first.

Question 18

Describe the process of the indirect ELISA.

Answer 18

1. Add antigen to well
2. Add serum containing antibodies
3. Add enzyme-linked antibody
4. Add colorless substrate
5. Development of color indicates presence of antibody

Question 19

What indicates the presence of antibodies in an indirect ELISA?

Answer 19

Development of color

The enzyme-linked antibody binds to the constant region of the antibodies.

Question 20

What is a lateral flow test?

Answer 20

A diagnostic test delivered at the point of care

Results can be obtained quickly, easily, and affordably.

Question 21

What diseases can a lateral flow test detect?

Answer 21

COVID-19, HIV, Ebola, possibly cancer

They are designed to test for various diseases.

Question 22

How does a lateral flow test operate?

Answer 22

Sample flows from sample pad to conjugate pad, binds to antibodies, produces detectable signal

The test line shows results based on antigen-antibody complexes.

Question 23

What happens if no disease-specific antigens are present in a lateral flow test?

Answer 23

The first set of antibodies will not attach to the test line

A control line will still appear to validate the test.

Question 24

What is a plasmid?

Answer 24

A circular segment of DNA found in bacteria

Plasmids allow bacteria to perform functions such as resisting foreign substances.

Question 25

What is the first step in gene cloning?

Answer 25

Isolate the target gene ## Footnote The target gene can represent specific traits, such as producing insulin.

Question 26

What role do enzymes play in gene cloning?

Answer 26

One enzyme cuts the plasmid, another glues the gene to the plasmid ## Footnote Enzymes act as scissors and tape in the cloning process.

Question 27

What occurs after inserting the plasmid into bacteria?

Answer 27

Bacteria reproduce, producing human insulin ## Footnote Each reproduction replicates the plasmid with the target gene.

Question 28

Fill in the blank: The enzyme that acts like scissors in gene cloning is used to _______ the plasmid.

Answer 28

cut open

Question 29

True or False: Gene cloning can produce large amounts of human insulin.

Answer 29

True ## Footnote Bacteria can multiply and produce insulin continuously.

Question 30

With ELISA, how can we tell if the patient was only vaccinated or infected with the virus?

Answer 30

Vaccinated people (with mRNA vaccines) only develop antibodies against the spike (S) protein, because the vaccine contains mRNA coding for that protein only. Infected people develop antibodies against multiple viral proteins, including The spike (S) protein, and The nucleocapsid (N) protein, among others. To determine if a person was infected (not just vaccinated), run an indirect ELISA test using the nucleocapsid (N) protein as antigen. If positive: they were infected. If negative: they were likely only vaccinated. If you want to know if the person is currently infected but don’t care about whether they were vaccinated then you can do a direct ELISA to look for antigens.

Question 31

Direct vs indirect ELISA

Answer 31

Direct: -uses antibodies to detect antigens -Detects current infection Indirect: - uses antigens and antibodies to detect antibodies - detects past infections or vaccinations (depending on which antibodies are tested)

Question 32

1. What is one difference between the direct and indirect ELISA test? A. In direct ELISA tests, antibodies bind antigens; in indirect ELISA tests antibodies bind antibodies. B. In direct ELISA tests, antibodies bind antibodies; in indirect ELISA tests antibodies bind antigens. C. In direct ELISA tests, antibodies lyse blood cells; in indirect ELISA tests antibodies bind antibodies. D. In direct ELISA tests, antibodies bind antigens; in indirect test antibodies bind complement proteins.

Answer 32

A. In direct ELISA tests, antibodies bind antigens; in indirect ELISA tests antibodies bind antibodies.

Question 33

What is required from the patient in a direct ELISA test?

Answer 33

Antigen

Question 34

How do rapid antigen tests used to detect SARS-CoV-2reveal the presence of viral antigens? A. Viral antibodies bind specific antigens attached to a paper strip, inducing a color change. B. Viral antigens bind specific antibodies attached to a paper strip, inducing a color change. C. Antibodies surround the virus, preventing it from causing a color change on the paper strip.

Answer 34

B. Viral antigens bind specific antibodies attached to a paper strip, inducing a color change.

Question 35

Why do many diseases, such as measles, occur only once in a person, yet others, such as colds, occur more than once?

Answer 35

Many diseases like measles typically occur only once because the immune system produces strong, long-lasting memory B and T cells after the initial infection. These memory cells recognize the virus quickly if it’s encountered again, preventing illness. However, illnesses like the common cold occur more than once because ** they are caused by many different viruses ** (like rhinoviruses, coronaviruses, etc.), each with slightly different antigens. Even when memory cells exist for one strain, they may not recognize a new one. **Additionally, some cold viruses mutate rapidly, changing their surface proteins and evading immune memory, ** leading to repeated infections.