Pandemic flu

Question 1

Why does flu only affect the respiratory tract?

Answer 1

Haemagglutinin cleaved (activated) by host cell proteases only found in the respiratory tract

Question 2

Influenza replication cycle

Answer 2

• Haemagglutinin binds sialic acid receptors on host cell
• Enters cell in endosome
• Acidic pH of endosome triggers release of RNA
• RNA goes to nucleus - viral proteins encoded
• New viruses released via neuraminidase

Question 3

What population harbours influenza virus?

Answer 3

Migratory waterfowl

Question 4

Influenza Tx

Answer 4

Antivirals in severe disease, vaccinate high risk groups

Antivirals - NEURAMINIDASE INHIBITORS - Oseltamivir (Tamiflu, oral)
- Zanamivir (Relenza, inhaled)
Both effective against Influenza A + B

Amantadine used to target Haemagglutinin (Influenza A only) but resistance gained so no longer useful

VACCINATION

Question 5

DIfferent types of vaccine

Answer 5

• Children 2-17 = live attenuated quadrivalent
• 18-65 at risk (e.g. health workers) = inactivated quadrivalent
• > 65 = inactivated trivalent with adjuvant (HA protein

N.B. Live attenuated more powerful to tackle children who are common spreaders; elderly have weakened immune response so need boost from adjuvant

Question 6

Influenza A vs. Influenza B

Answer 6

Influenza A more serious

Tamiflu + Relenza act on both Influenza A + B