VM 232: Microbiology II – UE 2014
Question 1:
(a) Briefly, hypothesize the origin of viruses (6 marks)
(b) Provide THREE (3) functions for each of the following viral components
(i) Viral proteins (3 marks)
(ii) Viral capsid (3 marks)
(iii) Viral envelope (3 marks)
(c) Using a diagram alone, illustrate the Baltimore classification system (5 marks)
Question 2:
(a) Viruses hijack cellular processes in living cells in order to complete their replication cycle. With examples,
i. briefly explain ONE stage that can occur in dead cells (5 marks)
ii. briefly explain ONE stage that cannot occur in dead cells (5 marks)
(b) To complete their replication cycle, viruses utilize several enzymes.
i. with examples, briefly explain why viruses package enzymes within their virions (5 marks)
ii. with examples, briefly explain why viruses package enzymes within their envelope (5 marks)
Question 3:
Dengue virus is a single-stranded positive sense RNA virus.
a) mention the common features between the dengue virus genome and cellular nucleic acids (5 marks)
b) briefly describe how the dengue genome is replicated (5 marks)
Question 4:
a) Define these terms (each 1 mark)
i. Antigenic shift
ii. Antigenic drift
iii. Antigenic mimicry
iv. Antigenic variation
v. Antigenic variation
b) Briefly in 2-3 sentences write on how the following mechanisms bring about anti-viral immunity
i. CTLs (each 3 marks)
ii. T helper cells
iii. NK cells
iv. Antibody-dependent cell mediated cytotoxicity
v. Interferons
Question 5
a) Draw the basic structure of an immunoglobulin molecule (IgG), clearly showing its main structural features (5 marks)
b) Explain why IgM is always the first antibody type produced in a primary immune response
(5 marks)
c) Describe the principle of clonal expansion, and with a diagram show how clonal expansion may differ in primary and secondary immune responses (10 marks)