Virology Review Questions - Topic 1.
1. Enveloped viruses are typically less robust or stable than naked viruses when outside of the
host cell. Suggest reasons as to why this might be so.
2. Define the term “host range” from a virology perspective.
3. A virus may have a very limited host range or a very broad host range. What determines
the host range of a virus?
4. A new virus is able to infect a monkey cell but not a human cell when cultured in the
laboratory. However, if the genome is extracted and then micro-injected into a human cell,
a productive infection will occur. In other words, progeny viruses are produced. Is the
human cell susceptible and/or permissive?
5. Blocking viral attachment and entry is the best way to prevent a potential infection. In
many cases, such as the antibodies generated by our own immune responses, the anti-
receptors on the viruses are neutralized. An alternative method would be to block the virus
receptor; however, this is not done very often. Suggest reasons why this might not always
be a possible therapy for prevention of infection?
6. There are three basic types of vaccines used to induce immunity for prevention of infection
by viruses. What are they? What are the advantages and disadvantages of each type? If
you were asked to design new vaccines for Ebola virus and the common cold virus, what
type of vaccines would you use? What would be the criteria used in making your decision?
7. Why are there relatively few effective anti-viral drugs when compared to anti-bacterial
agents? Why aren’t such drugs used to treat common viral illness such as colds?
Virology Review Questions - Topic 2 - Picornavirus Case Sudy.
8. Enteroviruses such as poliovirus, are known for being transmitted via the fecal-oral route
and causing disease. What physical traits do these viruses have that allow them to carry
9. Why does the poliovirus utilize a polyprotein strategy when translating its mRNA? Why
aren’t the individual viral genes translated separately into the individual proteins?
10. In a laboratory experiment, human cells were infected with poliovirus and a mutant version
of poliovirus is isolated. In this mutant, the entire 5’ UTR region of the genome is deleted.
When this mutant virus is used to infect new host cells, what process(es) will be affected by
this deletion? What will the effect be on the virus replication cycle?
11. What is VPg and why is it important? If the gene encoding VPg was deleted, what effect
would this have on the virus replication cycle?
12. What would be the advantage to the virus in using a “replication compartment” to replicate
its genome instead replicating its genome in the cell’s cytoplasm? 2
13. With the destruction of certain host components by poliovirus, host cell protein synthesis is
no longer initiated since the ribosomes cannot recognize host mRNA. Is this an advantage
or disadvantage for the poliovirus? Specifically, what feature of poliovirus allows it to
utilize the cell’s ribosomes? How does this feature work?
14. What is the purpose of (–)-sense RNA strand in poliovirus genome replication? Why is it
vital that the (+)-sense and not the (–)-sense RNA be packaged into the pro-capsids? What
allows for the proper loading of the (+)-sense RNA?
15. How many copies of VP0, 1 and 3 are in the pro-capsid? After the maturation of the virus,
what proteins are present and how many copies of each?
16. What are the two types of vaccines are used to induce immunity against poliovirus? What
specific forms of immunity do they induce? From the point-of-view of a physician
practicing in Vancouver, what are the important advantages and disadvantages of using
each type? What type is typically used to vaccinate children in North America? Would
this vaccine be sufficient for a child that travels to areas where poliovirus is still endemic?
Virology Review Questions - Topic 2 - Orthomyxovirus Case Study.
17. Describe the structure of the influenza virus genome? What are the fun