Hepatitis Viruses Flashcards
What are laboratory indications of liver failure/liver inflammation?
Elevated AST or ALT
Increased prothrombin time or INR
What is the definition of hepatitis?
Inflammation of liver which can lead to damage and potentially liver dysfunction
What are classic signs and symptoms of acute hepatitis?
Fatigue, nausea, vomiting, malaise, headache, chills
Abdominal pain (RUQ), loss of appetite
Chalky stools
Jaundice and icterus (bilirubin in skin & sclerae)
Is hepatitis B a RNA or DNA virus?
DNA virus (hepadnavirus)
What are the different core antigens of Hepatitis B?
Core antigen HBcAg
e antigen HBeAg
What is the e antigen of Hepatitis B?
Role not well characterized
Acts as an indicator of active viral replication and increased transmissibility
What is the surface antigen of Hepatitis B?
HBsAg - forms viral component of lipoprotein envelope
What is cccDNA?
Covalently closed circular DNA (tightly supercoiled)
What is the life cycle of HBV?
Binds via surface antigen
Uncoats into cytoplasm
Nucleocapsids release ‘relaxed’ circular DNA (rcDNA) into nucleus
rcDNA is repaired to yield cccDNA (covalently closed circular DNA)
cccDNA is transcribed to 4 viral mRNA
- Smaller mRNAs transplated into structural proteins
- Larger mRNA packaged with RT into core particle
- Larger mRNA is finally transcribed by reverse transcriptase into negative strand DNA
Virion can then be released
How long does cccDNA persist in host?
Indefinitely, never removed completely from nuclei of host
What causes the liver damage associated with Hepatitis B?
Immune response (primarily cytotoxic T cell response) to viral antigens expressed on hepatocyte cell surface
How many genotypes are there of Hep B?
8 (A-H)
What are modes of HBV transmission?
Sexual, parenteral, perinatal
What body fluids have highest concentration of Hep B virus?
Blood, serum, wound exudates
Semen, vaginal fluid, saliva are moderate
What age will show clinical symptoms of Hep 5?
Usually > age 5
Under age 5 don’t have a fully functional immune system, and immune response is what causes clinical presentation
What age is more likely to develop chronic infection from acute infeciton?
Usually < age 5
Immune system is not fully developed and cannot fight off disease as well
(>90% of children progress to chronic, <5% of adults)
What are the different serologic markers of Hepatitis B?
HBsAg HBeAg Anti-HBs Anti-HBe Anti-HBc (IgM) Anti-HBc (IgG) HBV DNA
What is the definition and clinical use of HBsAg?
Hepatitis B surface antigen
General marker of infection
First serologic marker to appear
Persistence for >6 months = chronic infection
What is the definition and clinical use of HBeAg?
Hepatitis B e antigen
Indicates active replication of virus
What is the definition and clinical use of Anti-HBs?
Antibody to hepatitis B surface antigen
Indicates recovery from natural infection and/or immunity
Detectable after Hep B immunization
What is the definition and clinical use of Anti-HBe?
Antibody to hepatitis B e antigen
Marker of reduced level of replication
Not often done in acute evaluation
What is the definition and clinical use of Anti-HBc (IgM)?
Antibody to hepatitis B core antigen
Marker of current acute hepatitis B infection
What is the definition and clinical use of Anti-HBc (IgG)?
Antibody to hepatitis B core antigen
Marker of current or past infection
What is the definition and clinical use of HBV DNA?
Hepatitis B virus genomic DNA
Marker of HBV replication
Used for monitoring response to therapy
What is the first serologic marker of HBV to appear?
HBsAg
Can you ever see expression of HBsAg and anti-HBs serologic markers at the same time?
No, there is window period between these two
What is serologic profile of someone with an active acute Hepatitis B infection?
HBsAg POSITIVE Anti-HBs NEGATIVE Anti-HBc (IgM) POSITIVE Anti-HBc (IgG) NEGATIVE HBV DNA POSITIVE