Hepatitis Viruses Flashcards
what organ do hepatitis viruses target?
the liver
where do hepatitis viruses primarily infect and replicate?
hepatocytes
what causes the liver damage?
virus and host response
what kind of infections do hepatitis viruses cause?
acute or chronic
what is the virus family, genome and virion for Hep A?
- picornaviridae
- (+)ssRNA
- non-enveloped
what is the virus family, genome and virion for Hep B?
- hepadnaviridae
- circular dsDNA
- enveloped
what is the virus family, genome and virion for Hep C?
- flaviviridae
- (+)ssRNA
- enveloped
what is the virus family, genome and virion for Hep delta?
- deltaviridae
- (-)ssRNA
- enveloped
what is the virus family, genome and virion for Hep E?
- calciviridae
- (+)ssRNA
- non-enveloped
**which hepatitis viruses are transmitted by fecal-oral method?
HAV, HEV
**which hepatitis viruses are transmitted by sexual method?
HAV, HBV, HCV, HDV, HEV
**which hepatitis viruses are transmitted horizontally?
HBV, HCV, HDV
** which hepatitis viruses are transmitted parenterally?
HAV, HBV, HCV, HDV, HEV
which to hepatitis viruses are rare in the US
HDv & HEV
which hepatitis virus is the most prevalent in the US?
hep B then hep A then hep C
**what kind of virus is hep B?
- hepadnaviridae
- genome: dsDNA, smallest genome of the human viruses
- virion: enveloped
- proteins:
- reverse transcriptase: required to complete DNA
can hep B be grown in cell culture?
no
describe hep B replication
- genome has RNA intermediate
- cccDNA is template for transcription
- requires liver specific transcription factors
- produces many empty particles (HNsAy); present in infected people
*RNA pregenome packaged into capsid–>reverse transcriptase and ccDNA formation –>progeny virus
how does hep B spread?
sexual and drug use
what is the hep B incubation period?
30-180 days LONGGG
what is the symptom onset for hep B?
- general malaise, anorexia, vomitting, fatigue, cough, serum-like sickness
- jaundice, elevated alanine transaminase (ALT) levels
what is the recovery like for hep B?
~3-4 months after onset of jaundice
can chronic disease occur with hep B?
yes in about 5% of cases
presence of HBsAg in blood for >6mos confirms chronic infection; marked by poor IgG resposne
what effect does hep B have on the liver?
- causes cirrhosis
- incr. risk for hepatocellular carcinoma (HCC)
- HBV X gene/protein has tumorigenic potential
- liver will go through active regeneration so the more it does this the more chance for mutation –> cancer
how is hep B prevented?
- vaccination:
- available, first recombinant vaccine approved for use in humans
- requires multiple inoculations
- not effective against chronic infection
how is hep B control if chronic?
- interferon-alpha therapy
- nucleoside analogs: adefovir, lamivudine, tenofovir
**what kind of virus is hep D?
- subviral agent:
- rare in human viruses
- only other example is adeno-associated virus (AAV) which requires adenovirus infection
- requires active HBV infection***
- RNA genome encodes a single protein
what kind of virus is hep C?
- flaviviridae
- genome: (+)ssRNA
- virion: enveloped
- proteins:
- E1&E2 attachment and entry
- C: core
- various non-structural
where is the genome replicated?
cytoplasm
T/F: in HCV, chronic infections are much more common (80%) than HBV and there are milder signs and symptoms
T
HCV is an extrahepatic disease… what is meant by this?
-mixed cryoglobulinemia: antibody and virus complexes deposit in other tissues (eg. kidneys) eliciting an immune response and subsequent tissue damage
is there a vaccine for HCV?
no, just interferon-alpha treatment to reduce chances for chronic infection
how is hep A spread?
ingestion of fecally contaminated food or water
absorbed through intestine and moves to liver via portal system
what is the incubation period for hep A?
15-40 days
what are symptoms of hep A infection?
- consistent with hepatitis infection: malaise, anorexia, vomiting, jaundice
- more severe in adults than in children
- resolves approx. 8 weeks post infection
how is hep A prevented?
vaccine available- kill/inactivated vaccine
what does hep E virus cause?
food-borne and waterborne hepatitis
what disease is very similar to HAV?
HEV so must be distinguished by serology
can HEV infection be life threatening?
yes for prego women
is the prevention for HEV?
nope
