#15 viral hepatitis Flashcards
what is hepatitis
inflammation of the liver
what are symptoms of acute hepatitis
- dark urine
- pale faeces
- jaundice
- flu like symptoms
how long does acute hepatitis last for
weeks to months
how long does chronic hepatitis last for
years to lifelong
what cells are infected from hepatitis
liver cells called hepatocytes
what causes liver damage in hepatitis?
the immune response against the virus
how can hepatitis enter the hepatocytes?
via immune cells in the circulation
via the circulation
via DCS
what are later phase symptoms of hepatitis
cirrhosis of the liver from chronic liver damage - can damage and lose function of the liver
hepatocellular carcinoma
is hepatitis cytopathic
no - its non-cytopathic
what determines the outcome of hepatitis infection?
age related outcomes!
younger people will have a less severe acute infection but they will have a higher chance of developing a chronic infection (as they have a immature immune system)
older people will have severe acute infection vbut may clear the virus and not become chronic
is there cross reactivity between the hepatitis viruses
there is no cross reactivity
infection with one virus will not protect from another hepatitis virus
can you clear Hep. B?
no - lifelong infection
can you clear hep. c?
no - lifelong infection EXCEPT if you are treated with antivirals
where is the source of Hep A and Hep. E
faeces
how do you catch Hep A and E
contaminated water or food/ fecal oral route is the main source
however it can be transmitted by blood, and sexual activity!
what type of infection is Hep A and E
acute
how can you prevent hep. E
clean drinking water
how can you prevent hep. A
pre or post immunisation
how is Hep. B transmitted
percutaneous
or
permucosal
how is Hep. C transmitted
percutaneous
or
permucosal
how is Hep. D transmitted
percutaneous
or
permucosal
what type of infection is Hep. B C and D
chronic
where is the source of Hep B C and D
blood and bodily fluids
how do you determine an acute infection?
ELISA serological test: test for high IgM - IgM presence or rising IgG to viral proteins is an indicator of a acute infection
can you use nucleic acid tests to detect acute infection?
PCR yes - but it will not tell you how long the person has been infected for like ELISA can
what family is Hep. A and what is the genome
does it have an envelope
picornaviridae
small +ssRNA
no envelope (resistant to stomach acid)
is there a vaccine for Hep. A
yes
it can be cultured
describe the life cycle of Hep A and E
- virus ingested via food or water
- replicates in the intestine epithelium then accesses blood to perform primary viremia
- accesses hepatocytes
- replicates in liver and is secreted into bile and faeces
what is the incubation period for Hep. A
30 days
what are the symptoms by age for Hep. A
- under 5 less than 10% will show symptoms
- over 14 70-80% will show symptoms
what are the symptoms of Hep. A
pale faeces
dark urine
jaundice
vomiting
what is the chronic sequalae of Hep. A?
none. doesnt cause chronic infection
when can you measure virus in the faeces in Hep. A infected patient
virus can be measured in faeces before symptoms appear
what antibodies will be produced in a hep. a infection
firstly IgM will be produced then when the virus is being cleared they will class switch to IgG
what family is Hep. E in
does it have an envelope
what type of genome does it have
Hepeviridae
its a Hepevirus
no envelope
+ssRNA
what are outbreaks of Hep. E associated with
outbreaks of fecally contaminated drinking water
how do you prevent Hep. E
clean sanitised drinking water
what is the incubation period for Hep. E
40 days
what is the chronic sequalae for hep E
none - does not cause a chronic infection
what does ALT mark
ALT is a marker of virus replication in the liver. increased ALT means increased virus replication
when do the symptoms of Hep. E show in comparison to when the virus is detectable?
the virus is detectable before the presence of symptoms
what family is hep b
what is its genome
is it enveloped
hepadnaviridae
dsDNA
enveloped
what are HBsAg
Hep. B surface antigens. they are produced as non-infectious particles
they circulate in high levels in the blood
contain only envelope proteins
what does the Pre-C region encode on Hep. B
it is the pre-core region on the genome
encodes for HbeAg
it is antigenic
it determines replicating virus in cells
explain the lifecycle of Hep. B
- virus enters via blood or sex or needles
- if its on the mucosa it will penetrate into the blood (if transmitted by needle it already enters the blood)
- will access hepatocytes of liver and replicate there
(it only replicates in the liver!!)
how much is Hep. B concentrated in secretions and blood?
highest in blood and serum
moderate: semen, vaginal fluid and saliva
low/not detectable: urine, faeces, sweat, tears, milk
what is the incubation period for Hep. B
60-90 days
what is the rate of chronic infection in people less than 5 yrs old for hep B
60-90% develop chronic infection due to immune system unable to clear the virus
what does the outcome depend on for hep. b infection?
the immune system
under 5: low acute phase, high risk of chronic infection
over 5: acute phase severe, and less likely to develop chronic hep. b
if a person develops chronic Hep. B what else can develop
- chronic > cirrhosis > liver cancer (end stage)
what is the serological response of a Hep. B acute infection?
- HbsAg rises as virus is replicating
- immune response may cause symptoms
- HbeAg will be measured in early stages - this will in the later stages switch to Anti-Hbe which indicates the virus is being controlled and will be cleared!!
what is the serological response of a Hep. B chronic infection?
- HbeAg will be ongoing and is showing that virus is replicating - indicator of chronic virus
- no Anti-Hbe will be made
- there are sustained levels of Ab for the core protein -AntiHbc
- no viral clearance
what is the sequelae of Hep. B
chronic infection
causes liver damage from the immune system
cirrhosis, liver failure, hepatocarcinoma
Hep. B is most common cause of liver cancer
how can hep. b infection be prevented
vaccination
it can be cultured
how is hep. b diagnosed
- A battery of serological tests are used for the diagnosis of acute and chronic hepatitis B infection.
- HBsAg - used as a general marker of infection
- Anti-HBs Ig - used to document recovery and/or immunity to HBV infection, but also successful vaccination
- anti-HBc IgM - marker of acute infection
- anti-HBc IgG - past or chronic infection
- HBeAg - indicates active replication of virus and therefore effectiveness of therapy.
- Anti-HBe Ig - virus no longer replicating. However, the patient can still be positive for HBsAg which is made by integrated HBV
HBV-DNA - indicates active replication of virus, more accurate than HBeAg especially in cases of escape mutants. Used mainly for monitoring response to therapy
what does Hep. B vaccine protect against
Hep. B and D
what family is Hep. D
what is its genome
Deltavirus
+ssRNA - highly complimentary
what us unique about Hep. D infection
it only co-infects with Hep. B
it uses Hep. B surface antigen to gain access to hepatocytes
what family is Hep. C
what is its genome
flaviviridae
+ssRNA
80% of Hep. C infections occur through….
intravenous drug use
what percentage of people develop chronic hep. c infection
70% - high!
is there a vaccine for Hep. C
no - no animal model either
what proteins make up the viral RdRp of Hep. C
NS5B protein and NS3 protein make up the RdRp. it is highly error prone and introduces mutations
what is the incubation period for Hep. C
6-7 weeks
what percentage of people become infected with Hep. C
70% - high!
what is the sequalae of Hep C
liver damage - cirrhosis
is the primary cause of hepatocellular carinoma
can Hep. C be cured?
yes - with antivirals
