SOKOINE UNIVERSITY OF AGRICULTURE
COLLEGE OF VETERINARY MEDICINE AND BIOMEDICAL SCIENCES
DEPARTMENT OF MICROBIOLOGY, PARASITOLOGY AND BIOTECHNOLOGY
BLS 113: VIROLOGY THEORY PROBATION/FIRST SITTING 2021
Instructions:
- Answer ALL questions
- Diagrams SHOULD be drawn neatly
- Read each question CAREFULLY before you start attempting
QUESTION 1 (25 marks)
Provide a brief explanation of the following words/terms used in virology (2.5 marks each):
a) Virus
b) Virion
c) Prion
d) Provirus
e) Viroid
f) Virusoid
g) Positive sense RNA
h) Permissive cell
i) Cell transformation
j) Viral tropism
QUESTION 2 (25 marks)
Some viruses possess an outer covering referred to as an envelope while others do not.
a) What advantages and disadvantages do envelope viruses have over naked ones? (6 marks)
b) Where and how do enveloped viruses acquire their envelope? (4 marks)
c) What is the envelope of a virus made up of? (3 marks)
d) What is the role of surface glycoproteins (ligands or spikes) that are embedded in the envelope? (3 marks)
e) What happens if the envelope is removed from an enveloped virus? (3 marks)
f) Draw a well-labelled diagram of an enveloped virus (6 marks)
QUESTION 3 (25 marks)
Coronavirus disease 2019 (COVID-19) was reported for the first time in Wuhan, China and has affected millions of people worldwide. The control of the disease is based on social distancing, wearing masks, washing hands with water and soap, and the use of sanitisers and vaccines. Several vaccines have been developed and approved for use in humans and the results are promising.
Based on the information provided above and your knowledge of COVID-19, answer the following questions.
a) Name the virus responsible for the COVID-19 pandemic (2 marks)
b) Is the virus naked or enveloped? (2 marks)
c) Provide the names of proteins found on the virus used for attachment and the receptor where the virus attaches (4 marks)
d) Explain why social distancing, wearing masks, washing hands with soap and the use of sanitisers are important aspects of fighting against COVID-19? (8 marks)
e) What do sanitisers do to the virus making them important in the control of COVID-19? (4 marks)
f) Name any THREE vaccines which are currently used to control COVID-19 in the world (3 marks)
g) Which TWO vaccines have been adopted for use in Tanzania? (2 marks)
QUESTION 4 (25 marks)
a) Use a clear diagram to illustrate a complete infectious cycle of an enveloped virus (10 marks)
b) Describe the importance of each step of the complete virus infectious cycle illustrated in “a” above (15 marks)
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