Lecture 4 - Antigenic variation

Question 1

What are the main survival strategies of pathogens?

Answer 1

Parasites must combat or avoid immune systems of hosts:
Immune suppression – helminths (trying to develop drugs based on strategies helminths use)
Immune avoidance – intracellular parasites (going intracellular as soon as possible)
Immune evasion – masters of disguise (antigenic variation)

Question 2

Describe the envelope structure of influenza

Answer 2

Two important proteins:

Hemagglutinin (HA) : Attaches to host receptors

Neuraminidase (NA) : Breaks down sialic acid to allow budding.

Question 3

Describe influenza and antigenic variation

Answer 3

Antigenic drift:
Minor mutations occur as a result of the low fidelity viral polymerase.

Antigenic shift:
Viruses infecting different species recombine (in a permissive host) leading to major genomic changes (reassortment of viral genome).