BLS 113 UE July 2024

SOKOINE UNIVERSITY OF AGRICULTURE 

COLLEGE OF VETERINARY AND MEDICAL SCIENCES 

DEPARTMENT OF MICROBIOLOGY, PARASITOLOGY AND BIOTECHNOLOGY  

EVEN SEMESTER UNIVERSITY EXAMINATION  23^RD JULY 2024

 

EXAMINATION PAPER: VIROLOGY (BLS 113)

 

PROGRAMME: BACHELOR OF BIOTECHNOLOGY AND LABORATORY     SCIENCES

 

TME ALLOWED: 15:30 – 18:30

 

VENUE: ENG 5 & 7

 

EXAMINATION NUMBER: ……………………………………

 

Instructions to Candidates

• Answer ALL questions
• Take note of the mark’s distribution
• Observe all instructions in your answer book
• Observation of General University Examinations Regulations is vital

                                                     

QUESTION ONE (25 Marks)

Use a tabular format (see example in the first row) to;

(i) name the virus groups based on Baltimore classification,

(ii) state the sites where genome replication and transcription take place, and

(iii) state whether the virus group packages any enzyme within its virion or not.

Baltimore Class	Virus group	Site for genome replication	Site for transcription	Package enzyme (s) or not
Class I (smaller)	ds DNA Viruses	Nucleus	Nucleus	No
Class I (larger)
Class II
Class III
Class IV
Class V (segmented)
Class V (non-segmented)
Class VI
Class VII

 

QUESTION TWO (25 Marks)

The figure below represents a structure of HIV. Use the figure below and your general knowledge on HIV to answer questions that follows.

• (i) Name the parts labelled 1-7 (7 marks)
• (ii) What is the main function of the parts labelled 2, 4, 5 and 6 in the figure above (8 marks)
• (iii) What was the criterion used to name the group of viruses where HIV belong? (2 marks)
• (iv) Explain why HIV is smaller than bacteria? (3 marks)
• (v) Discuss why HIV can only replicate inside living cells? (5 marks)

 

QUESTION THREE (25 Marks)

A group of scientists has developed novel antiretroviral drugs targeting key enzymes involved in the replication cycle of HIV.

• (i) What are the three key enzymes that are potential targets? (6 marks)
• (ii) Describe how these drugs interfere with the replication cycle of the virus, preventing its spread within infected individuals and potentially serving as a treatment option (15 marks)
• (iii) Explain why targeting more than one point in the replication cycle is important in preventing the replication of the virus (4 marks)

 

QUESTION FOUR (25 Marks)

A patient infected with influenza A virus is not responding to standard antiviral treatment. Sequencing of the virus reveals several mutations in both the hemagglutinin (HA) and neuraminidase (NA) genes. These mutations in influenza virus are mainly due to reassortment events that lead to antigenic shift.

• (i) Explain the difference between antigenic shift and antigenic drift in the context of influenza virus mutations (10 marks)
• (ii) Describe how pigs serve as “mixing vessels” for influenza virus reassortment leading to mutations in the HA and NA genes (15 marks)

 

QUESTION SEVEN (25 Marks)

• (i) Differentiate between viral infection and virus pathogenesis (6 marks)
• (ii) Explain the cellular changes induced by viral infection (15 marks).
• (iii) How do cellular changes affect the host cell’s structure, function, and viability? (4 marks)

                                                     

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