hepatitis viruses - Hepatobilary system Flashcards
hepatitis
general term referring to inflammation of liver
causes
1) infectious
- viral
- bacterial
- fungal
- parasitic
2) non infectious
- alcohol
- drugs
- autoimmine
- metabolic
progressions of hepatitis
chronic hepatiti
cirrhosis
hepatocellular caricnoma
signs and symptoms of hepatitis
malaise jaundice dark urine pale fatty stools serum and urine biochemicstru
what is a complete virus called
virion
general viral structure
strand of nucleic acid DNA/RNA
surrounded by protective protein coat (capsid)
sometimes have lipid membrane (envelope) surrounding the protien
types of hepattis
A B C D E
how are the types of hepatitis split
how they are spread A and E - foetal oral spread others - parenteral route (i.e. any route apart from faecal oral)
Hep A
picorna virus genotypes 1 7 1-3 and 7 human disease foetal oral spread 2 week incubation 4-10 day prodrome
prodrome
early symptoms
what are their vaccines fro
A and B
antibody general reponsce and what do they indicate
IgM produced first when host exposed to antigen
then delclines
IgG produced, remains high (IgG indicated part infecion/immunity, IgM indicate acute or primary infections
serology of Hep A
- incubation period at start
- prodrome phase (early symptoms start)
- virus detectable before prodrome
- IgM starts production, then declines
- IgG after, remains high
Hep B viral structure
- central core with the double stranded DNA, DNA polymerase, Hbc antigen
- breakdown product of Hbc is Hbe antigen which is found in the serum (marker of active infection)
- surrounded by envelope
- produces Hbs Ag (from the surface), shedding from the surface you can get spherical or filament forms, but these are non infective
- only the whole virion is infective
what is the whole vision of Hep B called
dane particle
infecive
what can Hep B develop into
25%
1) chronic persistent hepatitis
- ‘healthy carrier’
2) chronic active heptattis
Hep B spread
parenteral route (vertical, parenteral, sexual)
dsDNA virus
resides and multiples in hepatocytes
non infective Hep B
filament
spheres
of HBs
what does the DNA of hep B code fro
4 genes
1) S
- codes for surface antigen
2) C
- core protien
3) P
- polymerase
4) X
- regulatory in terms of viral replication
HBc gene and transcription
HBc gene split into two
- pre C
- core gene
When transcribed there is a signal peptide at the start, which is modified by protease
- either cuts the signal peptide fully off or partially off
- if some pre C left peptide left, forms Hbe antigen (secreted and can be found in serum)
- if fully cut off, C antigen produced (not secreted)
seriology of acute Hep B infection / lab detection
Focused on detection of Hep B surface antigen (HBs Ag) - first produced in repsonce
- acute HBV infection characterised by presence of HBs Ag and IgM to the core antigen HBc
Initial phase of infection
- pts seropositive for Hep Be antigen
- usually marker of high levels of replication of the virus
- Presence of HbeAg indicates blood/fluids of individual are highly contagious
serology of chronic Hep B infection and what is the marker indicating
- persistence of HBsAg for at least 6 months (with/without HBeAg) as HBs remained elevated
- persistence of HBsAg is principle marker for developing chronic liver disease and liver cancer (hepatocellular carcinoma) later in life
percentage of chronic infection progressing to chronic liver disease hep c
10
hep D
caused by defective RNA virus
- has to co exist with HBV
- small virus
- outer coat derived from HBs Ag, cannot survivie without HBV
ie Those with Hep B can be Hep D positive
hep D virus
RNA virus
- delta antigen surroudsn the RNA
- delta antigen is looked for in sero diagnosis
- coat derived from Hep B surface antigen
hep C viral structure
small enveloped single stranded RNA virus (SSRNA)
- core of genetic material surrounded by icosahedral capsid
- lipid envelope
- inside the envolope is two glycoproteins, E1 and E2 (help the virus bind to host cells)
- complex genome, 10 genes transcribed as one long protein which is then cut into 10 different proteins
- E2 is responsible for attachment to host cells via scavenger receptors B1 and CD81
hep C progression
50-85% become chronic - 50% fatigue - 25% cirrhosis - 5% HCC (carcinoma) Persistence - low replication rate - variants selected by non reactivity with Ab
treatment of Hep C
interferon A + ribavirin
hep E
RNA herpesvirus
4 genotypes
foetal oral spread
diagnoiss of Hep E
PCR
serum IgM/IgG Abs
vaccines for d?
No specific vaccine for D as you can only get it with B, if vaccinated for B will not get D
