M- Hepatitis Viruses Flashcards
What is the mode of transmission of HepA?
Where is infection with this virus most common?
What can stop the spread?
Fecal-Oral
- food and water
- household contacts (most common)
- sexual contacts
Common in developing countries- hand washing can stop spread
What is the mode of transmission of HepE?
It is transmitted by the fecal-oral route.
- Water (most common route)
- some food (pork)
Common in developing countries
Describe the genome of Hep A and Hep E.
HepA is RNA with 3 domains encoding structural and non-structural proteins
HepE is RNA with 2 domains encoding structural and non-structural proteins
What characteristic of the virion of HepA and HepE allow it to spread by the fecal oral route?
They have no lipid coat so detergents are not able to digest and destroy their infectivity.
How does HAV infection present in:
- young children
- older children and adults
- asymptomatic
2. jaundice
Who is most likely to present with acute liver failure (fulminant hepatitis) from an HEV infection?
Women in the third trimester of pregnancy
What serology markers are measured for HepA?
Which are markers of acute infection?
Which are markers of prior infection?
Acute infection:
- IgM HAV Ab
- Total (IgG+IgM) HAV Ab
Prior infection:
1. Total (IgG+IgM) Ab
What serology markers are measured for HepA?
Which are for acute?
Which are for prior infection?
Acute:
- IgM HEV Ab
- IgG HEV Ab
Prior:
IgG HEV Ab
What is the therapy for HAV and HEV?
- Supportive- anti-emetics, IV fluid, cholestyramine
If they have fulminant hepatitis they need a transplant
What is prevention AFTER exposure for HAV?
within 2 weeks the person can get intramuscular injection of ISG (immune serum globulin) an antibody titer to prevent clinical HepA
What is prevention of HAV before exposure?
Active immunoprophylaxis:
a vaccine made of formalin activated HepA antigen
Describe the virion and genome of HBV.
Virion: Coat with host lipids
Genome: DNA with overlapping strands
Describe the structural genes and proteins of HBV.
Describe the non-structural genes and proteins of HBV.
Which gene is viral specific and consequently a drug target?
Structural:
- pre-S1, pre-S2, S (surface antigens)
- C gene (core antigen)
Non-structural:
- P (polymerase)*** viral specific so drug target
- pre-C (e antigen)
- X gene
What part of HBV is done by host machinery?
What part of HBV replication is done by viral machinery (polymerase)?
Host:
HBV DNA is used to generate RNA transcripts to translate viral proteins (specifically polymerase)
Viral:
- polymerase does reverse transcription
- RNAse
- DNA-dependent DNA synthesis
When can HBc be detected in the blood?
Where does immunohistochemical staining show HBc?
It can only be detected in the blood if the surface coat is removed.
Immunohistochemical staining using HBc antibody can demonstrate the presence of HBc in the nucleus of infected cells
What are the 3 ORFs of HBV? Which genes are in each?
- Polymerase has its own
- HBc, HBe and HBs are on one ORF
- HBs from a much shorter RNA transcript… This makes surface coat too small to attach to hepatocytes but makes spheres and filaments