Study questions for Topic 8 (Viral infections and Pathogenesis)

Persistent infections

1. What is the difference between an acute infection and a persistent infection? Give one example of each type of infection.
2. What must happen for a persistent infection to be established?
3. Why are some organs more conducive to establishing persistent infections than others? What are some examples of these organs?
4. What is the state of the viral genome during a persistent infection?
5. Know one viral persistent herpesvirus infection so that you can describe how it is acquired, the symptoms of the disease, and how persistence is maintained.
6. What is a necessary prerequisite for defining an infection as latent?

Acute infections

1. What events take place during the incubation period of an infection? Why are acute infections public health problems?
2. Why do we distinguish between acute and inapparent acute infections?
3. Describe features of one of these viruses that make it an acute infection: influenza, poliovirus, measles virus, rotavirus, West Nile virus
4. How are infections with the following viruses transmitted: influenza, poliovirus, measles virus, rotavirus, and West Nile virus.
5. What causes the paralysis of polio? Is everyone who is infected paralyzed? Does quarantine work to prevent the spread of infection?

HIV pathogenesis

1. How is AIDS controlled? Can an infected individual be ‘cured’ of the virus? Why or why not?
2. What is the origin of HIV-­1?
3. What is a clade and why is it important? How is HIV‐1 transmitted? Is it very infectious?
4. What are the different stages of a HIV­‐1 infection? Why does HIV­‐1 infection cause immunosuppression? What causes death in end-stage AIDS patients?
5. Is the course of HIV-1 infection always the same? What are the problems in designing an AIDS vaccine?
6. Describe the pathogenesis, laboratory diagnosis, and treatment of HIV infection

Transformation and oncogenesis

1. What is meant by the term “transformation” in the context of the transforming retroviruses? What are the three ways that RNA tumour viruses transform cells?
2. Is HIV capable of transforming cells like RSV? Why or Why not? Do tumour viruses ‘need’ to transform cells? Explain.
3. How do DNA tumour viruses transform cells? Know about the roles of T antigens, Rb, and p53. RNA and DNA tumour viruses transform cells. What happens next to make these transformed cells oncogenic? Does the virus play a role in these events?
4. Why do DNA tumour viruses cause tumours only rarely, and in the ‘wrong’ hosts?
5. Enlist the oncogenic viruses. Describe the mechanism of oncogenic transformation.

General for viral infections and pathogenesis

Which of the cellular processes described in this chapter are limited only to enveloped viruses compared to nonenveloped viruses?

Make a table listing each portal of entry. What defences does the host have at each location and how are viruses able to successfully bypass them?

Describe the architecture of the skin and how viruses gain access to each layer and the subcutaneous tissue.

How do localized infections become systemic infections?

Describe how different factors could affect the inactivation of virions within the environment.

Draw out the stages of infection after a person is infected with a virus.