Influenza virus pandemic

Question 1

Influenza life cycle

Answer 1

o HA binds to Sialic Acid receptors (SA-R) on human URT cells and human tryptase cleaves the HA to allow entry
o The acidity of the endosome triggers a fusion event by which it releases its genome into the cell
o The genome then travels to the nucleus and takes over host factors to drive transcription and translation
o New viral products produced (proteins and genome)  assemble at surface of cell and bud off

Question 2

What mutation do influenza viruses need to infect humans

Answer 2

PB2 mutations

Question 3

What is antigenic shift

Answer 3

• This is when a single cell is infected by both a human virus and a bird virus
• They then shuffle their RNA  production of a bird virus that can infect a human

Question 4

Mechanism of neuraminidase inhibitors

Answer 4

NA is required to leave the cell by binding to the receptor and cleaving its way out the cell
So NAi prevents this

Question 5

Antiviral therapy uses

Answer 5

o Not used in combination (unlike HAART)
o Antivirals tend to be used for the first 3-6 months of a pandemic however, a 2014 SLR found “no evidence… to use these drugs to prevent serious outcomes in annual influenza and pandemic influenza outbreaks

Question 6

Types of antiviral therapy

Answer 6

o	Amantadine:
	Targets M2 ion channel 
o	Neuraminidase Inhibitors:
	Tamiflu (oseltamivir) – oral	
o	Polymerase Inhibitors

Question 7

Influenza vaccine used in at risk groups

Answer 7

A purified fraction containing HA and NA of an inactivated virus

Question 8

Vaccine given to children

Answer 8

live attenuated vaccine [intranasal]
• Live attenuated, also tri- or quadrivalent
• Cold-adapted virus limited to URT

Question 9

Universal flu vaccine

Answer 9

 Target the stem of the HA instead of the head
 Most antibodies bind to the head of the HA molecule
• Very plastic and change every year
• The stem, however, does not change
 This stem is shared across all strains of influenza