MD 2

What type of viruis is influenza? three key components?

orthomyxoviruis

ssRNA

enveloped

recognises sialic acid receptors

what are the key viral components of influenza?

hemmaglutinnin (H) - attachement protein

neuraminidase (N) - helps release new viruises from infected cells

vRNA - viral genetic material

what does Hemagglutinin (HA) do?

functions in attachement and penetration

what does neuraminidase (NA) do?

cleaves sialic acid from glycoconjugates, releases progeny virions

what does M2 do?

helps release viral RNA inside cell

what are the 5 stages of the influenza replication cycle

1. attachment - HA binds sialic acid receptor

2. endocytosis

3. uncoating - M2 helps viral RNA escape

4. replication

5. assembly

6. budding/release - NA cleaves sialic acid

what is the structure of Heamagglutinin

globular head - binds to sialic acid receptor

fibrious stem - anchors protein and helps fusion

what does Neuraminidase do

enzyme that breaks down the sialic acid receptor on the cell surface - heamagglutin protein can no longer bind

whats the innate response to influenza infection?

1. NFkB activation

2. NFkB transcription pathway increases inflammatory cytokines

3. these recruit NK cells, B cells, T cells

4. Th1 response - promoting antivrial immunity

whats the 5 long term responses to influenza infection?

Th2 response

T cell stimulation

antigen presentaion

B cell muturation

antigen specific IgG production

what are the 4 types of influenza

A,B,C,D

A&B - cause seasonal epidemics

C - mild respiratory illness

D - primarily infect cattle

what are the two subtypes of influenza

hemagglutinin and neuraminidase - based on protein on the surface of the viruis

IgG antibody will only recognised one subtype of H or N it was generated against

what is antigenic drift

small gradual mutations in viral proteins - antiboids no longer recognised viruis well

when does seasonal influenza peak?

December - February

what are most influenza vaccines?

inactivated

produced by growing the bacteria or viruis in culture media then inactivating it with heat and/or chemicals - cannot cause disease from infection

2 pros and 2 cons of inactivated vaccines

generally safer, improved stability

can be costly, hypersensitive

whats the standard flu vaccine?

trivalent inactivated vaccine

two strains of A and one of B

whats the traditional vaccine production?

egg propagation - viruis grown inside fetilised chicken eggs

time consuming, expensive

what are the 4 critical factors in influenza vaccine production?

1. growth potential of seed viruis - some strains grow poorly limits vaccine supply

2. timing of strian selection

3. potency test reagents

4. timing of annual license supplement approval

what type of cells does cell based vaccine production use?

MDCK cells

2 advantages to cell based strain producition

antigenic match

scalability