L17- GI Infections VII (viral hepatitis) Flashcards
Viral Hepatitis:
- (1) are the main viruses that cause primary inflammation of the liver
- (2) are the other viruses causing liver inflammation
- (3) name the types of viral hepatitis (define them)
1- HepA/B/C/D/E
2- HSV, CMV, EBV, YFV (yellow fever)
3- Acute <6mos, Chronic >6mos
for each Hepatitis virus, list its envelope status, genome type, and viral family
HepA: non-enveloped, (+)ssRNA, picornavirus
HepB: enveloped, partial dsDNA, hepadnavirus
HepC: enveloped, (+)ssRNA, flavivirus
HepD: enveloped, (-)ssRNA, deltavirus
HepE: non-enveloped, (+)ssRNA, hepevirus
list the Viral Hepatitis symptoms (including phases)
1) Prodrome / pre-icteric: fever, n/v, loss of appetite, chronic fatigue, abdominal pain/swelling, leg swelling, easily bruised, itchy skin
2) Icteric / jaundice: jaundice, bilirubinemia, dark urine color, pale stool color (or bloody or tarry)
In LFTs:
- (1) are liver injury indicators
- (2) are liver function indicators
1- AST, ALT, LDH, ALP
2- bilirubin (total, direct, indirect), albumin, PT
describe the distribution of Hepatitis viruses based on infectious type
HepA, HepE = ‘infectious’; enteric transmission (fecal-oral)
HepB, HepD, HepC: ‘serum’, parenteric transmission (transmission thru blood, sex)
HAV:
- (1) genome, structure [family]
- stable in the following conditions, (2)
- inactivated in the following conditions, (3)
1- non-enveloped, icosahedral // (+)ssRNA // picornavirus
2- pH = 1.0, solvents (ether, chloroform), detergents, saltwater, groundwater, drying, temperature (survives wks at 4C, 1/2hr at 56C)
3- formalin, UV radiation, chlorine Tx of drinking water, temperature (partial form at 61C for 20 mins)
HAV replication (initial steps):
- enters the body via (1)
- attached to (2) cells
- genome is delivered to (cytoplasm/nucleus)
1- ingestion (fecal-oral) of contaminated food/water/ect
2- Kupffer cells (liver macrophages)
3- cytoplasm
HAV replication (later steps):
- genome is translated into (1) and then processed via (2)
- (3) is one of the results from (2) and is responsible for (4)
- (5) is the final step
1- (cytoplasm) single long polypeptide
2- cleaved via proteases into protein (peptides)
3- RNA dependent RNA polymerase
4- copies RNA –> (+)/(-)ssRNA
5- viral assembly and release via exocytosis
Most cases of viral hepatitis result from Hep(1). The most deaths from viral hepatitis results from Hep(2).
1- HepA (40%)
2- HepB (~47% of total deaths), HepC (~48%)
describe the transmission of HepA
-fecal-oral: virus can shed before or in the absence symptoms (90% children, 25-50% adults) and is shed at high concentrations
(rarely has person-to-person transmission, via blood)
- extremely stable virus
- most outbreaks occur at schools, camps, daycare, restaurants
- worldwide, all year long
HepA:
- Sxs are milder in (adults/children)
- (2) incubation period
- (3) main Sxs
- (4) main signs (excretions / labs)
1- children
2- 3-4wks (~30 days, range 15-50 days)
3- (abrupt onset, intensified before icteric phase) fever, fatigue, nausea, loss of appetite, abdominal pain [inc chance of jaundice with inc age]
4- (same as other hepatitis) dark urine, pale feces, elevated ALT > AST
describe the detection (/diagnosis) of a HAV infection
-clinically: Sxs time course, common sources
Serology (in chronological order):
1) virus in feces (2-6wks)
2) IgM (starts 4wks, peaks 6wks) –> acute infection
3) IgG (starts 5wks, peaks 8wks and beyond) –> previous infection
HAV:
-(1) is the main prevention method; (2) are other good practices
-(3) is about the only treatment
1- vaccine (killed / inactivated)
2- good sanitation, proper personal hygiene, preventing food/water contamination
3- prophylaxis with Immune Serum Globulin (passive immunity) –> prevents illness if given before or <2wks after exposure
HEV genome, structure [family]
non-enveloped, icosahedral
(+)ssRNA
hepevirus family
HEV:
- (1) main geographic areas
- can result in (acute/chronic/both) viral hepatitis
- worst / life-threatening in (3) patients
1- Asia + India, Africa, Mexico
2- acute (presents like HAV- no chronic infections)
3- pregnant patients
HEV:
- (1) Dx, Tx
- (2) prevention
1- no standard tests (PCR is best but not always available), no standard Tx
2- (NO vaccine) avoid beverages with ice of unknown purity, uncooked shellfish, uncooked fruits/veggies
describe HEV Serology (chronologically- include presence in blood/stool, jaundice timeframe, ALT, IgM, IgG)
1) (1-2 wks before Sxs) HEV in blood
2) (~1wk before Sxs, up to 3wks after) HEV in stool
3) (3-4wks once Sxs start) jaundice
ALT: 2-4wks after Sxs start, peaks at 2wks
IgM: 10wks after Sxs start, peaks at 2wks
IgG: (forever) surpasses IgM at 4wks
HCV:
- (1) genome, structure [family]
- replication in (cytoplasm/nucleus)
- (3) are the main structural proteins (membrane) in mature virons
1- enveloped, icosahedral // (+)ssRNA // flavivirus
2- cytoplasm
3- capsid + E1, E2 (virus-encoded membrane proteins)
HCV replication:
- after inoculation, particles will attach to (1) and enter cells via (2)
- (3) briefly describe genomic replication
1- multiple LDL-R and or VLDL-R
2- receptor mediated endocytosis + acidification
3- translation into single polypeptide –> RNA dep. RNA poly. replicates RNA –> (+)/(-) ssRNA
HCV:
- (1) are the main reservoirs
- (2) predominate transmission
- mostly is seen as a (acute/chronic) infection
1- humans
2- blood (IV drug use, sex, transfusions)
3- chronic (+ asymptomatic) infections [5-30 yr development]
HCV:
- replicates in (1) cells, which will be destroyed via (2)
- (3) is important in the resolution of HCV infections (indicate importance)
- chronic infections lead to a higher risk for (4)
1- hepatocytes (although not cytopathic)
2- immunopathogenesis
3- humoral and cellular immunity- therefore worse in the immuno-compromised (co-morbidities)
4- HCC
HCV Dx:
- (1) and (2) are used to detect Igs
- seroconversion occurs (3) post-infection
- it is difficult to detect Igs in (4) patients
- (5) is used to detect viral genome
1- ELISA 2- RIBA (recombinant immunoblot assay) 3- 7-31 wks 4- viremic, immunocompromised, hemodialysis 5- RT-PCR (in blood or liver)
what are the requirements for diagnosing a chronic HCV infection
- elevated liver enzymes
- positive anti-HCV Ab test
- positive HCV RNA test
- > 6 mos
in HCV serology, (1) peaks first and (2) peaks second
1- ALT
2- IgG
HCV:
- (1) prevention
- (2) Tx
1- (no vaccine) screening of blood for transfusions, eliminate ‘risky’ behavior
2- (prophylactic Igs ineffective) IFN, antiviral polymerase inhibitors (nucleo-side/-tide analogs), antiviral protease inhibitors
GB-C virus = (1)
- (2) describe genome
- (3) reservoirs
- (4) transmission
- (5) is a unique feature
1- HepG virus
2- enveloped, (+)ssRNA, flavivirus
3- humans (GBV-C), monkeys (GBV-A, GBV-B)
4- sex, blood
5- interferes with HIV pathogenesis / replication
-causes decade long chronic infection
