VM 235: VETERINARY VIROLOGY
DATE: 04th February 2022 TIME: 15:00-18:30 HRS
INSTRUCTIONS: ATTEMPT ALL QUESTIONS
Use well-labelled diagrams where necessary
QUESTION ONE (25 Marks)
a) Differentiate the microorganisms in the table below by ticking (√) the correct feature (s) against each microorganism (13 marks)
| Microorganism
/Feature |
DNA genome | RNA genome | Small RNA | Circular ss RNA | Single protein | Capsid | Spikes |
| Bacteria | |||||||
| Fungi | |||||||
| Virus | |||||||
| Viroids | |||||||
| Virusoids | |||||||
| Prions | |||||||
| Hepatitis delta virus |
b) Prions are infectious agents consisting of a single type of protein molecule which causes prion-spongiform diseases such as mad cow and scrapie spongiform encephalopathy in cattle and sheep respectively. Briefly describe the mechanism that leads to the development of prion diseases (12 marks)
QUESTION TWO (25 Marks)
a) Frank Fenner (1914-2010), a professor of virology used mice to study the classical pathogenesis of ectromelia (mousepox) viral infection. Briefly, describe how the different stages of pathogenesis for mousepox infection were demonstrated in the mice (10 marks)
b) Briefly describe the principle and or mechanism of action of the following;
c) HIV nucleoside-analogue reverse transcriptase inhibitors (4 marks)
d) Nucleotide Reverse Transcriptase Inhibitors (4 marks)
e) HIV resistance to Azidothymidine (AZT) (7 marks)
QUESTION THREE (25 Marks)
Answer the following questions below in relation to severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and the coronavirus disease 2019 (COVID-19).
a) Name the cell and the receptor used by the virus (4 marks)
b) Describe how SARS-Cov-2 enters and leaves the cell? (8 marks)
c) Name any three SARS-Cov-2 variants resulting from viral mutations (3 marks)
d) Name and state the function of the protein where the mutations leading to SARS-Cov-2 variants take place? (4 marks)
e) With one example in each case, name any FOUR types of vaccines that are used to control COVID-19? (4 marks)
f) Name TWO types of vaccines that have been adopted for use to control COVID-19 in Tanzania (2 marks)
QUESTION FOUR (25 Marks)
Foot-and-mouth disease (FMD) is a highly contagious disease of domesticated production animals including cattle, pigs, sheep, and goats FMD’s etiological agent is a small non-enveloped positive-sense single-stranded RNA virus (FMDV) of the Picornaviridae family and contains a small genome of about 7.2-9.1 kb. Vaccination is the main tool for FMD control. Based on this information, answer the following questions below.
a) Classify FMDV based on the Baltimore system (2 marks)
b) Briefly describe how genome replication and protein synthesis is done for FMDV (8 marks)
c) Where does the replication of the FMDV genome take place in the infected cell? (2 marks)
d) How does the virus exit the infected cell? (3 marks)
e) Explain why RNA viruses like FMDV are far more susceptible to mutation than DNA viruses? (4 marks)
f) Briefly describe how vaccinating animals against FMD may prevent future infections caused by FMDV (6 marks)
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