Lecture 10; Influenza Flashcards
What are the two proteins of influenza virus?
Heamagglutinin and Neuraminidase
Write some notes about influenza A,B,C
Influenza A (Avian to humans / other mammals) Seriously illness, epidemics and pandemics.
Influenza B (Human virus) Serious illness and epidemics
Influenza C (Humans to pigs) Minor illness
What clinically differs influenza from the common cold?
- SYSTEMIC i.e chills, myalgia, malaise
- ABRUPT onset
- High fever (38) Usually
- Cough and sore throat
- UNWELL FOR 1-2 WEEKS
- Severe complications possible i.e pneumonia
- Seasonal
Write some clinical notes on the common cold;
- Local; Nose and throat
- GRADUAL
- Usually mild
- Sneezing, sore throat, congestion
- RAPID RECOVERY
- ALL YEAR ROUND
Describe the rapid onset of influenza and its association with inflammatory markers;
In influenza that virus titre rapidly increases and peaks at day 2 post innoculation, this is associated with the highest symptom score and highest level of IFN-alpha.
i.e Rapid onset of symptoms caused my viral damage and immense immune system reaction.
Worst part of influenza occurs early on. With other inflammatory markers rising later indicating continued illness.
Is influenza present year round?
No influenza is seasonal and rates of infection drop near zero during off season.
Describe the replication cycle of influenza;
Influenza enters the cell and its envelope opens release viral proteins and DNA which are taken up into the nucleus. The DNA is transcribed to produce RNA which uses cellular machinery to make viral proteins. The virus components then buds off the cell (Formation of envelope) to form new virus’.
What are the three common influenza in circulation?
A H1N1
A H3N2
and influenza B (Has only one H and N sub type)
Of the common influenza how do they change?
Mutation of surface proteins = Antigenic drift
New type of influenza A = Antigenic shift (i.e rapid change) (This only occurs in influenza A)
What is Antigenic drift?
Gradual mutations in virus that changes the shape of haemagglutinin
Whats the function of haemagglutinin?
Haemaglutinin binds sialic acid (component of cell receptors) found present on various epithelium i.e back of nose.
What is the function of neuraminidase?
Neuraminidase cleaves the interaction between haemagglutinin and sialic acid which is very strong and prevents virus leaving till cleavage. i.e this is the anchor for new virions.
What are neuraminidase inhibitors?
Oseltamivir and zanamivir and they prevent the cleavage of the Hg-Sialic acid bond and thus prevent viral release.
Is oselatamivir useful?
Only if used early on in the illness and side effects tend to be worse.
What is the influenza vaccine?
No virus, just H and N proteins.
Tends to be trivalent containing proteins of H1N1, H3N2 and B.
Prevents 40-80% of cases
