viral hepatitis Flashcards
what is classified as chronic hepatitis?
> 6 months abnormal LFT ad serology
stages of hepatic fibrosis
- fibrous expansion of some portal areas
- expansion of most portal areas with some portal bridging
- fibrous expansion with marked portal bridging
- cirrhosis
how does HepB replicate?
- replication of DNA genome by reverse transcription of RNA intermediate
how does the innate immune system respond to HepB?
- PAMP recogiese by TLR3
- leads to downstream RIG1 signalling
- activates interferon regulating factors
- NF-KB release
- Activates interferon stimulating genes
- activates INF a/b
what effect does INF a/b have on hep b?
- down regulates viral protein synthesis
- inhibits viral replication
- promotes adaptive immunity via MHC class 1
- activates NK, CD8 and dendritic cells
- activates cell death through secretion of perforins
how does HBV evade detection by the host?
- stealth virus via cccdna
- foxp3 expressed on t regs
surpasses T cell response to HBV - cD8 is upregulated- more apoptosis and T cell specific response is reduced
- CTLA4 and CD152 ‘turn off’ immune response
- IL10 also down regulates the immune response
which 2 factors result in persistent infection?
age of infection- infants will have tollerant response leading to persistence
immune suppression- won’t have adequate response to wipe out virus
how does the adaptive immune system respond to HBV?
- HBsAb neutralises virus
- forms complex with antigen and prevents uptake by hepatocytes
what percentage of people clear HBV?
95
how long does immunity against HBV last?
lifelong
what can chronic HBV lead to?
HCC
cirrhosis
wha are tx for chronic HBV?
- pegylated interferon
- tenofovir
- entecavir
loss of antigen happens rarely
which immune factors lead to clearance of hbv and which reduce spread?
clearance= cd4 and cd8
reduced spread= antibody
what percentage of people develop chronic HCV?
80
does HCV have a vaccine?
no
