SOKOINE UNIVERSITY OF AGRICULTURE
College of Veterinary Medicine and Biomedical Sciences
VM 235: Veterinary virology CAT 2 Total Marks: 70 Date: 16th January 2022 Time: 1 hour
1. Why do you think the incubation period between HIV infection and AIDS has typically been 10 years or more? (6 marks)
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2. For a viral disease to develop, the virus must implant and replicate at the portal of entry, spread and replicate within the host target organs and finally shed out to the environment.
a) Why must the virus replicate at the portal of entry before disseminating to target organs? (4 marks) ……………………………………………………………………………………………………………………………………………………………………………………………………………
b) Provide any four routes that can serve for both entry into the host and shedding of the virus to the environment (4 marks).
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3. For ensuring a successful virus infection, sufficient virus particles and the host cells must be available. What are the three main qualities that must be provided by a cell for successful virus infection (3 marks)
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4. Whenever there is a successful virus infection, it implies that the local host antiviral defence systems are absent or are at least initially defective. Briefly potentiate this statement (6 marks)
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5. It has been well said that a virus is a piece of bad news wrapped up in a protein and that no virus is known to do good. Briefly support and oppose this statement based on your knowledge on viruses (10 marks)
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6. It is not in the interest of the viruses to severely harm or kill the host because their life is entirely dependent on the living host cells. Describe how viruses kill the host cell they infect leading to death of the host (6 marks)
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7. In most cases we can be infected with viruses, become sick for about a week and recover without any treatment. Explain briefly what happens in the body until we recover from the illness? (10 marks)
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8. One of the experimental approaches to preventing viral infection is to use recombinant DNA technology to artificially synthesize the host cell receptor molecule to which a specific virus would normally attach and then therapeutically administer this receptor to people prior to viral exposure. Discuss briefly how this might offer protection to the body (8 marks)…………………………………………………………………………
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9. Briefly describe how vaccinating animals against viral infections may prevent future infections to the target viruses (8 marks)
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10. How do antiretroviral drugs that bind to HIV-encoded protease help to reduce the number of HIV in the body? (5 marks)
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