Viral Hepatitis Flashcards
aOf the Hep. viruses, which one is the only one with a DNA genome?
Hep B
Which of the Hep. viruses are transmitted via fecal-oral route? Blood route?
Which Hep virus has the greatest transmission during sexual encounters?
Fecal oral: AE
blood: BCD
greatest transmission: Hep B, followed by Hep D.
Of the hep. viruses, which ones increases one’s risk of hepatocellular carcinoma?
BCD (also the same ones that are transmitted via fecal oral route)
What type of viruses are Hep. A, B, C, D, and E?
A = picoRNAvirus
B = HepaDNAvirus
C = Flavivirus
D = satellite
E = Calcivirus
What is the incubation periods for Hep. A, B, C, D, and E?
Hep A, D, E: 2 wks - 7/9 wks
Hep B: 6 wks - 6 mo. (avg 120d)
Hep C: 2 wks - 6 mo (avg 45d)
What are the main symptoms of chronic hepatitis? (7)
Fatigue
Decreased Exercise Tolerance
Anorexia
Arthralgias
Malaise
Weakness
Depression
Hep A
What is the international age-related prevalence?
How is it spread?
Risk factors?
developing countries = greater prevalence in the young
developed countries = “ ” adults
Spread via fecal oral route
Risk factors
- areas of decreased sanitation (low socioeconmic areas, inadequate hygiene)
- international travel (Mexico, Central/South America)
- Household contact
- Homosexual contact
- Food
- Daycare
- IV
Hep A
What type of virus is it?
What is the genome?
Does it have an envelope?
PicoRNAvirus
+RNA
no envelope
Hep A Life Cycle
What is the incubation period?
What is the disease progression after one is infected?
Are adults or children more likely to be symptomatic of the disease?
2-7 weeks (avg 30d)
- prodromal period (1 wk), followed by:
- increase in liver enzymes (>1000)
- concurrent development of jandice, fever, bausea, vomiting, abdominal pain
- development of antibodies (HAV-IgM - active infection; HAV-IgG - recovery)
- majority recover (no carrier state, no chronic hepatitis, no chronic phase)
Adults
Why do the majority of patients recover without development of chronic hepatitis?
Why would some patients get better but then become jaundiced again?
it’s an RNA virus. Once the infected cells are destroyed, the person is usually clear of the disease.
Relapsing: either due to a new infection or relapse
What two serologic studies would you perform on a HepA patient?
HAV-IgM
HAV-IgG (previous exposure or vaccination)
T/F 24 year old female develops acute Hepatitis 3 months after going to India. You tell her she likely has HAV.
False. HepA does not take that long to develop
T/F 32 year old with acute hepatitis have serologies anti-sAg+ and anti-HAV IgM+ has HAV
True
T/F: 50 year old Dart prof with HCV ab (+) anti-HAV ab (-) wants to go to Central America. You strongly recommend vaccination.
True
When does fecal shedding occur in HepA patients?
before patients become symptomatic
Hep B
Where is it most common? least common?
How is it acquired in these areas?
What are the risk factors of HepB?
most common in Asia and Africa (acquired perinatally, during childhood)
less common in the US (acquired via sex, IVDA, immigrants from high prevalence areas)
Risk Factors:
- Birth in high/intermediate prevalence HBV area
- Household or sexual contacts of HBsAg(+) persons
- History IVDA
- History of multiple sexual partners, STD
- Men who have sex with men
- Inmates of correctional facilities
- Chronic elevation of ALT or AST
- HCV or HIV infectionPatients undergoing renal dialysis
- All pregnant women
Hep B
What family is it?
What is the genome?
What are the 4 major genes and what proteins does they encode? (yep this is actually relevant)
DNA virus
hepaDNAviridae family
genome: relaxed, circular, partially ds-DNA, where the + strand is NOT complete and the – strand is complete
Encodes for
- pre-S1, preS2 and S - encodes for viral envelope/surface antigens
-
pre-Core and Core - encodes for HBeAg and HBcAg, respectively
- these can self-assemble into capsid-like structuresHBeAg is felt to be an immune tolerogen (an antigen that induces tolerance)
- DNA Polymerase - multifunctional (reverse transcriptase, DNA polymerase, ribonuclease)
- X protein - pleiotropic activities, among which is its ability to interfere with cell viability and stimulate HBV replication
What is unique about the Hep B polymerase?
multifunctional: reverse transcriptase, DNA polymerase, ribonuclease)
What is the lifecycle of the hep B virus like?
- Viral DNA polymerase synthesizes the partially ds DNA -> cccDNA (covalently closed circular DNA)
- cccDNA transcribed by host RNA polymerase into RNA, which enters the cytoplasm to be transcribed into:
- sAg envelope proteins in the ER -> can be packaged with polymerase/genome or self-assemble into 3 HBV particle types: spheres, filaments, and intact virions found in high abundance within the serum of an acutely infected individual
- intact virions “Dane particle” – infectious; contains nucleocapsid encasing genome and polymerase that is covered with sAg
- filament and sphere – consists only of sAg; non-infectious
- sAg envelope proteins in the ER -> can be packaged with polymerase/genome or self-assemble into 3 HBV particle types: spheres, filaments, and intact virions found in high abundance within the serum of an acutely infected individual
- Polymerase
- Pol-RT produces (-) DNA from RNA template
- Pol-Rnase degrades RNA, resulting in a single strand of (-) DNA
- Pol-DNA produces (+) DNA g dsDNA and circularizes it
- core proteins
- surrounds the Pol-DNA + dsDNA to form a nucleocapsid, which is transported to the ER to pick up sAg envelope proteins, golgi, and subsequent exit from the cellthe nucleus to increase cccDNA -> amplification
Hep B
Incubation time?
What is the natural progression of the disease once someone is infected?
- 50-65% have no symptoms
- 1% goes on to develop acute fulminant hepatitis
- recovery in 90% of immunocompement patients; 1-2% develop chronic hepatitis
natural progression and effects on liver
- perinatal transmission
- Immune tolerant
- Active
- Seroconversion
- inactive-> clearance, OR inactive -> active
- latter due to to mutation in HBeAg. this results in a virus that is much less efficient in replication, resulting in lower viral loads, but you can still see inflammation and fibrosis in the liver
What does this patient have? How do you know?
Hep B infection
cells rich in HBsAg have a ground-glass appearance (arrow)
What is HBsAg?
When does it appear?
What does its presence indicate?
Surface antigen
- First marker of active infection
- Precedes ALT and clinical symptoms
- Presence indicates HBV infection (no sAg = no HepB infection)
- presence for >6 months defines chronic HBV infection
What is Anti-HBs?
When does it appear?
What does its presence indicate?
Antibody against surface antigen
- appears after HBsAg declines (indicates decline in viral load)
- indicates active immunity (protective antibody), passive immunity (vaccination) or exogenous administration** **(exogenous anti-HBs)
What is Anti-HBc?
When does it appear?
What does its presence indicate?
antibodies against core antigens
- IgM class: remains positive in acute infections and persists during the window phase (aka serologic gap) or reactivation of infection
- IgG class: indicates a history of HBV infection
What is the window phase (aka serologic gap)?
What infection do you normally see this in?
*high yield point*
Hep B infection
phase where HBsAg and anti-HBs are absent
What is HBeAg?
When does it appear?
What does its presence indicate?
e antigen
- Appears concurrent with or soon after HBsAg
- Loss = nonreplicative phase or replicative mutant
- indicator of replicative HBV