VM 235 Probation 2023

SOKOINE UNIVERSITY OF AGRICULTURE

  COLLEGE OF VETERINARY AND MEDICAL SCIENCES

 PROBATION/FIRST SITTING FOR 2nd YEAR BACHELOR OF VETERINARY MEDICINE

Course Ante:   VM 235  Course Title:  VETERINARY VIROLOGY

 DATE:  3^rd OCTOBER 2023                  TIME: 8:00-11:00 HRS

INSTRUCTIONS: ATTEMPT ALL QUESTIONS

                          Use well labeled diagrams where necessary

VENUE:   MLT 18                                                                        

QUESTION ONE (26 Marks)

a) List any four (4) kinds of subviral agents and state why EACH of these subviral agents does not comply with the classical definition of a “virus.” (8 marks)

b) Explain why viruses do not fit to the usual definition of life (10 marks)

c) Explain why studying virology is important to veterinary students (8 marks)

QUESTION TWO (24 Marks)

The figure below represents a structure of HIV. Use the figure to answer question ‘a’.

a)      Name the parts labelled 1 to 7 (14 marks)

b)     Provide one important function of following parts or components of HIV (14 marks)

i)       Surface glycoprotein or spikes___________

ii)     Viral capsid _________________________

iii)   Viral envelope________________________

iv)    HIV RNA genome_____________________

v)     Reverse transcriptase___________________

vi)    Integrase_____________________________

vii)  Protease______________________________

QUESTION THREE (25 Marks)

The figure below represents a replication cycle of Foot-and-mouth disease (FMD) virus, a causative agent of a highly contagious disease of domestic animals including cattle, pigs, sheep and goats. Use the figure to answer all the questions below it.

a) Name the processes taking place at A, B, C, D, E and F (6 marks)

b) How does the virus enter the host cell? (5 marks)

c) How does the virus obtain its envelope? (6 marks)

d) Mention any four (3) parts and one component (1) of the complete virus (4 marks)

e) Provide ONE main function for each part and a component mentioned in “d” above (4 marks)

QUESTION FOUR (25 Marks)

a) Most DNA viral genomes must enter the nucleus for replication while few DNA viral genomes replicate in the cytoplasm.

b) Explain this difference (6 marks)

c) State the problem that is created to DNA viruses which replicate in the cytoplasm (4 marks)

d) Explain how the viruses that replicate in the cytoplasm overcome this problem (6 marks)

e) All RNA viruses encode their own replication system. True or False? Why? (4 marks)

f) In the (–) sense RNA genomes, the (+) strands and mRNA are the same. True or False? Why or why not? (5 marks)                                                                                    

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