L7: Influenza Flashcards
Name 5 symptoms of influenza viruses.
- Fever
- sneezing
- aches/pains
- sore throat
- runny nose
- sometimes GI related symptoms
How long do flu symptoms usually last?
Approx. 7 days unless individual is immunocompromised
What are some key features of the virion and genome?
- Negative sense ssRNA
- segmented genome (8 segments encoding 11 genes)
- Enveloped with hemagglutinin (trimer) and neuraminidase (tetramer)
- virion has a half life of only a few hours at room temperature
What receptor does influenza use to enter epithelial cells?
- Sialic acid
How does an influenza virion exit a cell?
- through budding (probably from ER)
What is the primary function of neuraminidase?
- acts as a sialidase so it chops sialic acid receptors so viruses don’t keep reinfecting the same cells (prevents aggregation)
- makes up approx 17% of envelope proteins
What’s the difference between antigenic drift and antigenic shift?
- Drift = accumulation of mutations over time to slowly change epitopes
- Shift = reassortment of genome when cells are infected with 2 different strains of influenza virus
What is the function of HA?
- Mediates cell surface binding to sialic acid
- 18 different subtypes
What is the current dominant strain of influenza virus?
- H3N2
Pandemics have arisen as a result of which strains (reassortments)?
- H1N1
- H2N2
- H3N2
What makes highly pathogenic avian influenza so bad?
- carries a multi-basic cleavage site which means that pretty much any old protease in the host cell can chop it up into useful bits
- LPAI and non-avian flus have 1 cleavage site (transient infection)
What treatments can be used for flu?
- rest mostly
- can use anti-virals like Tamiflu (NA inhibitor), amantadine or rimantidine (M2 ion channel blockers)
