Virology: colds and influenza

Question 1

Describe the virus lifecycle:

Answer 1

virus attaches to host cell
virus releases genetic material into the host
then either infects more cells with the virus or releases its genetic material into the nucleus of that host cell, killing the host cell

Question 2

How does the body deal with viruses?

Answer 2

proteases break down the viral proteins which bind to MHC class 1 if epithelial cell infected or MHS class II if APC infected. The protein is transported by MHC to the surface of the cell where it can be seen by APC

Question 3

what are the different types of defences against viral infections?

Answer 3

cytokines secreted - non specific
NKC - more specific
T cell mediated killing - very specific

Question 4

How many types of influenza virus are there?

Answer 4

3 (a, b and c)

Question 5

What are the 4 important proteins in the influenza virus?

Answer 5

• hemagglutinin
• neuraminidase
• M1 protein
• M2 protein

Question 6

What is the function of hemagglutinin?

Answer 6

binds virus to the sialic acid receptors on surface of host cells (mainly epithelial cells in RT)

Question 7

What is the function of neuraminidase?

Answer 7

releases virions to outside the cell so the virus can infect other cells (by cleaving sialic acid groups)

Question 8

What is the difference between antigenic shift and drift?

Answer 8

shift: normal mutations (can be combination of viruses forming a new virus).
drift: mutations in hemagglutinin leading to new hemagglutinins every year, so can’t vaccinate against