Lecture 4 Viral Hepatitis Flashcards
What effects does HAV infection have on heme degradation?
Stops breakdown pathway of billrubin (degradatory product of heme)
jaundice, dark urine, pale feces
What is most common cause of hepatocellular carcinoma? Mechanism?
HBV; causes >500,000 cancer death annually
Two proposed mechs:
1) integration of vDNA into genome (HCV doesn’t do that)
2) hepatocyte destruction and rapid regrowth incr risk of mutation
increased risk of HBV—>cancer w/ EtOH abuse
Hepatitis A
Family = ?
Epidem = ?
Trans = ?
Pathogen w/ s/sx = ?
Dx = ?
Vaccines? = ?
Tx = ?
Family = picornaviridae
Epidem = overt dz less common in developing countries b/c nearly everyone seroconverts by age 5 and virus is mild chez les petits enfants; MAIS, dans les pays plus developés, il y a plus des adults immuno-naïve
Examples: 1) outdoor events w/o sanit, 2) raw shellfish contam w/ sewage; 3) within fam w/ small kid, 4) infected foodhandler, 5) imported contam food
Trans = F-to-O trans; blood if pt is viremic
Pathogen w/ s/sx = incub is 30 days; viremia—>liver—>anorexia, nausea, fever, jaundice elev. LFTs (e.g. AST); liver damage to cell lysis by replicating virions
There is no chronic stage
Dx = Anti-HAV-IgG and IgM sero assays
Vaccines? = killed IM vaccine
Tx = pooled Ig
Hepatitis B
Family = ?
Epidem = ?
Trans = ?
Pathogen w/ s/sx = ?
Dx = ?
Vaccines? = ?
Tx = ?
Family = Hepadnaviridae
Epidem =
Trans = sexual, blood, perinatal, needles
Pathogen w/ s/sx = 70 incubation;
Has chronic phase in 5% of cases. —>liver carcinoma and chornic hepatitis
Dx = HB-Ags from serum
Vaccines? = Yes, inactivated subunit vaccine given IM (only contain antigenic subunits)
Tx = pooled IgG for infants of known-infected mothers
Give alpha-INF w/ lamivudine, a chain-terminating RT inhibitor from HIV txs past
Hepatitis C
Family = ?
Epidem = ?
Trans = ?
Pathogen w/ s/sx = ?
Dx = ?
Vaccines? = ?
Tx = ?
Family = Flaviviridae
Epidem
20,000,000 chronically infected worldwide; men > women; caucasianc > Afr. Amer.; Age > 40 y/o; increased risk factors: coinfection (HBV, HIV), EtOH, steatosis (fat droplets in liver)
Trans
Mostly injection drug users, also: sex, vertical, tatoos; needlestick and transfusion RARE
Pathogen w/ s/sx
60 day incub.; 70-80% become chronic hepatitis pts!
Dx
PCR test of HCV RNA
Vaccines?
no, mutates incredibly fast
Tx
chronic: alpha-INF (expensive and not very effacious); consider ribavirin; new: HCV protease inhibs (telaprevir and boceprevir) can be given with other two
Hepatitis D
Family = ?
Epidem = ?
Trans = ?
Pathogen w/ s/sx = ?
Family = n/a b/c not true virus (Deltavirus genus)
Epidem = only those with Hep B; break-outs among pops w/ high HBV prev
Trans = venereal, parenteral, perinatal
Pathogen w/ s/sx = acute onset; can be life-threatening
Hepatitis E
Family = ?
Epidem = ?
Trans = ?
Pathogen w/ s/sx = ?
non-env (+)ssRNA from Hepeviridae
trans = f-to-o
contam water/food
only in developing countries
20% mortality w/ preg women
togavirus
Nucleic acid set-up?
Virion structure?
How does it multiply?
Examples?
NA = single (+)ssRNA
virion = icosahedral enveloped
REPLICATION:
1) uncoats in cytosol, 2) (+)ssRNA genome is translated into several structural and non-structural proteins (i.e. not just one large polypeptide like poliovirus), 3) makes RDRP to make (-)ssRNA template of its genome, 4) buds out through plasmalemma
EXAMPLES: rubella, arboviral encephalitises (WNV, EEE, WEE, etc.)
Hepadnavirus
Nucleic acid set-up?
Virion structure?
How does it multiply?
Examples?
NA = single, circular dsDNA (for most of its length; bizzare)
virion = icosahedral enveloped PLUS spherical and filamentous antigenic/sub-viral particles (also bizzare!)
REPLICATION:
1) in nucleus, virion’s DNA pol synths rest of DNA making circular viral genome
2) template for mRNA synth w/ host RNA pol
3) full-length (-)RNA made from this which will be converted into new DNA genome w/ reverse transcriptase encoded for by virion’s genome
EXAMPLES: HBV
