Emerging diseases

Question 1

Bind: human vs avian

Answer 1

In humans: HA binds to sialic acid alpha2-6 linked to galactose in their respiratory tract
Avian: HA recognises to sialic acid alpha2-3 Gal IN THEIR GASTROINTESTINAL TRACT
- single amino acid change can impact binding specificity preference

Question 2

shift vs drift

Answer 2

Shift
- pandemic causing
- caused by reassortment event or direct transmission
- completely new subtype

drift
- endemic causing
- acquisition of point mutations over time

Question 3

Previous pandemics

Answer 3

direct infection: Spanish flu H1N1
genetic reassortment: 1957 H2N2 Asian flu, 1968, Hong Kong flu, H3N2

Question 4

2009 influenza pandemic

Answer 4

• Novel H1N1 virus that no one had immunity towards
  
  • H1N1 virus had been circulating in pigs + multiple introductions of human and avian flu = novel H1N1 virus
  • First human case of new H1N1 in 2009 in Mexico - before then H1N1 was circulating in pigs only, who were also infected by avian and human viruses
    Reassorted before entering man
    not highly lethal

Question 5

High parthenogenic avian flu

Answer 5

H5N1
has a string of basic amino acids in cleavage site, which means that it does not have to be cleaved by tryptase, ubiquitous proteases can cut (Furin)
- can be systematic even to brain