Pandemic flu Flashcards
Rank these pandemics in order of number of deaths:
○ 1968 - Hong Kong Flu
○ 1918 - Spanish Flu
○ 2009 - Swine Flu
○ 1957 - Asian Flu
○ 1918 - Spanish Flu (50 million deaths)
○ 1957 - Asian Flu (2 million deaths)
○ 1968 - Hong Kong Flu (1 million deaths)
○ 2009 - Swine Flu (200,000 deaths)
influenza viruses are acquired in humans how?
zoonotic transmission initially - so reservoirs are animals
usually from Avian influenza viruses
The natural reservoir for influenza A viruses is __?
ducks (migratory waterfowl - eg geese and swans )
why does influenza cause respiratory disease?
because the virus requires activation by host cell proteases that are only expressed in the respiratory tract
what is the enzyme specific to the lungs that is responsible for cleaving influenza haemaglutinin?
Human airway tryptase: HAT
what is the mutation that is associated with bird flu being able to cross into humans?
polymerase protein - PB2 627K
which bird flu’s have a high mortality rate and why?
H7N9 - biggest pandemic threat
H5N1
cause massive cytokine response
two steps required for influenza viruses to infect humans ?
○ Acquire the ability to infect human cells (either by PB2 627K or by reassortment)
○ Develop the ability to transmit between humans : reassortment of genes and antigenic shift
uman influenza viruses are transmitted via __?
respiratory droplets
3 requirements necessary for a virus to cause a pandemic?
A pandemic virus will have novel antigenicity.
A pandemic virus will replicate efficiently in human airway.
A pandemic virus will transmit efficiently between people.
list some Features of HA and NA that affect influenza transmission - conferring ability to infect?
NA stalk length - longer stalk
Virion stability - HA should be stable at low pH to prevent dissolution in endoscopes
Receptor binding - HA adapted to bind a2, 6, SA
which influenza circulates in pigs?
H1, H3
Loss of which protein is linked with severe influenza?
IFITM3
Interferon Induced Transmembrane Protein 3
list 3 antivirals used in flu and their mode of transmission ?
Neuraminidase inhibitors and mode of administration:
Tamiflu (oseltamivir) oral
Relenza (zanamivir) inhaled or iv formulation
Amantadine:
Targets M2 ion channelDoes not work against influenza B or pH1N1 or seasonal H3N2
Polymerase inhibitors - Japan only
how has Emergence of multidrug resistant pH1N1 been reduced?
use of triple therapy
The seasonal influenza vaccine given to HIGH RISK GROUPS (e.g. > 65 years) in the UK is?
a purified fraction containing HA and NA of an inactivated virus
usually require an adjuvant to stimulate the immune response
every school-aged child in the UK of a certain age are given which vaccine ?
a live-attenuated vaccine
difference between the inactivated virus vaccine and live attenuated vaccines?
live vaccines provides a broader, more cross-reactive immunity than the inactivated vaccines
live: from cold adapted virus
characteristics of inactivated vaccine?
Split or subunit- HA rich
Novel oil-in-water adjuvants used in monovalent vaccines AS03 Pandemrix had which side effect?
Narcolepsy
narcolepsy involves which symptoms?
excessive daytime sleepiness
disturbed night time sleep
MOA linking vaccines to narcolpesy?
Vaccine generates cross reactive antibodies
These traverse into the CNS and bind to hypocretin receptor 2
Hypocretin production down regulated
sleep symptoms
where do antibodies bind on the influenza?
the stem on the spike protein (HA)
