Influenza and Corona Viruses Flashcards
Non-human animal surveillance
surveillance for viruses that could threaten wildlife, livestock & domesticated animals
In silico prediction developmet
development of computational methods for predicting emergence risk of zoonotic viruses identified from animal surveillance
Guided surveillance of samples from human illness
surveillance systems for early detection of spillover and emergence of novel human infections
Where does COVID-19 fall interms of transmission & mortality?
less of fatality rate but the transmissibility rate is higher
Overview of Influenza viruses
family Orthomyxoviridae
- (-)-sense, segmented, single stranded RNA viruses
- 4 genera: A, B, C, D
Which influenzavirus genera are associated as seasonal influenza viruses?
A, B and C
Influenza A and B can be associated with…
pigs
Influenzavirus A hosts:
wild aquatic birds, mammals, humans
Influenzavirus B hosts:
humans, seals, ferrets
Influenzavirus C hosts:
humans, dogs, pigs
Influenzavirus D hosts:
cattle
What is the relationship like for influenza (i.e. the pathway)?
NOT a direct linear relationship like ebola is
- most start with wild birds & then can take diff areas
What is the virology of Influenza A?
- cirnodal
- (-) RNA
- enveloped
- influenza virus genome is segmented (8 diff.) –> allow for influenza viruses to mix/match their segments, which increase complexity of influenza viruses (can increase virulence/pathogenicity)
- viral RNA-dependent RNA polymerase - have to carry their own RNA polymerase
- HA and NA proteins (guide the cells that the virus can attach too & also guide the antigens that we have to produce vaccines against)
Where do influenza A viruses circulate in?
humans, domestic animals, pigs, horses, poultry & migratory birds
What is the virology of influenza a?
- 16 diff HA subtypes identified
- 9 NA subtypes
- HA & NA are most antigenically variable (able to swap out & change)
- bat influenza A-like viruses increase this to 18 & 11, but cannot reassort with IAVs (monitor what they can do but haven’t seen it yet)
Influenza __ viruses are NOT divided into diff subtypes
B
Which viruses were seen to show reassortment?
1918 “Spanish influenza”
1857 “Asian influenza”
1968 “Hong Kong influenza”
Antigenic drift…
results in progressive changes of HA & NA antigenicity through mutations (re: seasonal flue)
- RNA can mutate (inability to proof read)
Antigenic shift…
results from genetic reassortment through RNA segment changes b/t different strains (re: pandemic flu)
- can produce drastic changes
What is the main take-away from the timeline of influenza pandemics?
everytime we have a pandemic virus that emerges, that pandemic virus becomes the new seasonal virus until it itself is replaces (either through another pandemic or through another large scale transmission event)
What happens when we get infected by influenza virus?
- binding & entry mediated by HA - sialic acids
- mediated by HA & MA (pH-dependent steps)
- pH shift (& virulent opens up)
Purpose of HA?
helps guide interaction b/t virus & host cell for uptake
Purpose of NA?
helps facilitate the release of new virulent copies
What is the influenza virus epidemiology?
- seasonal influenza outbreaks typ. occur in winter months
- symptoms: onset ~1-4 d post-exposure (quick)
- ~3-5 million cases of severe ILI globally each year
- transmission: presymp. phase (-1 d) to 5-7 d post-symp. onset
- transmission primarily in children
- droplets, aerosols & fomites
