Hepatitis Viruses Flashcards
What is the only DNA hepatitis virus?
HBV (B for Both)
Which hepatitis viruses are fecal-oral transmission?
A and E.
Which can cause acute viral hepatitis?
All of them.
Which can cause chronic disease?
B,C,D. (The ones transmitted by blood).
What family of virus is HAV in?
RNA picornavirus.
What are the structural characteristics of HAV/picorna?
naked. icosahedral. +ssRNA.
How long is the incubation period in HAV before pt develops acute viral hepatitis (if they do)?
Short, weeks (15-40 days). Often asymptomatic.
What does +HAV IgM indicate?
Acute hepatits A infection.
What does +HAV IgG indicate?
IgG antibody indicates prior HAV infection and/or prior vaccination. Protects against reinfection.
Who should be vaccinated?
Travelers to endemic areas. Starting in 2005, part of routine peds vaccinations.
What kind of virus is HBV?
DNA hepadnavirus. DNA = circular!
How is HBV transmitted?
Parenteral, sexual, perinatal.
What is the HBV virus called with it is intact?
Dane particle. Big ol’ Bad HBV. dsDNA w/ DNA polymerase surrounded by icosahedral capsid with antigenic protein spikes sticking out, all surrounded by an envelope.
What exactly is HBsAg?
Filamentous structures composed of the envelope and some capsid proteins that have broken off from the virion.
Forms spheres and tubules 22nm in diameter.
Not infective.
Why do we care about HBsAg?
Antibodies against HBsAg are protective.
What exactly is HBcAg?
It is the core of the virion, the capsid w/out the protein spikes. Antibodies against this are NOT protective.
What exactly is HBeAg?
A soluble component of the core that is released during active infection and viral growth. Indicates highly infectious state.
What is the job of the polymerase of HBV?
1) DNA polymerase will complete the partial dsDNA of the virus
2) Host RNA polymerase makes mRNA out of this, host machinery makes proteins
3) Viral DNA polymerase then REVERSE TRANSCRIBES viral RNA to DNA for genome of progeny
What are the four disease states that may be caused by HBV?
1) Acute hepatits
2) Fulminant hepatitis - severe acute hepatitis with rapid dxn of liver
3) Chronic hepatitis
4) Co-infection with HDV
What are the different possibilities with chronic HBV hepatitis?
1) asymptomatic carrier state
2) chronic persistent hepatitis - low-grade smoldering
3) chronic active hepatitis - has an acute hepatitis state that does not resolve w/in 6-12 months
How does liver injury occur in HBV?
Cell mediated immune system attack:
1) Viral antigens on the surface of infected hepatocytes are targets for cytotoxic T-cells.
2) Immune complexes of Ab-HbsAg deposit in tissues and activate immune system, resulting in arthritis, skin, kidney damage
How are immunosuppressed patients with HBV likely to present?
Asymptomatically. Liver injury is mediated by immune system.
What are some complications of chronic HBV?
1) Primary hepatocellular carcinoma. DNA gets incorporated into host DNA, janks shit up, triggers malignant growth.
2) Cirrhosis
What does the presence of HBsAG indicate?
Always means there is live virus and infection (either acute, chronic or carrier).
What does the presence of Anti-HBsAG indicate?
Immune/Cured –> Disease is cleared.
What does the presence of HBcAg indicate?
Antigen to core.
What is the difference between IgM anti-HBcAg and IgG anti-HBcAg?
IgM: New infection.
IgG: Old/chronic infection.
What may the sole marker of HBV be during the window period?
IgM Anti HBcAg
What does presence of HBeAg indicate?
High infectivity, virus going wild. V bad for preggos.
What does anti-HBeAg indicate?
Low infectivity.
What are the treatment options for chronic active/persistent HBV?
1) interferons
2) nucleoside/tide analogs
3) Combo of the two.
How does interferon help in the treatment of HBV?
1) Direct antiviral effect, inhibiting synthesis of viral
DNA and activating antiviral enzymes.
2) Exaggerates the cellular
immune response against hepatocytes infected with HBV by increasing the expression of class I histocompatibility antigens and by stimulating the activity
of helper T lymphocytes and natural killer lymphocytes
What kind of virus is HDV?
RNA delta virus. Nucleocapsid guy.
Why is HDV a Dumb virus?
It can only replicate with the help of HBV. Uses HBV’s envelope, HBsAg. Needs the HBsAg coat! Similarly, antibodies against HBV are protective against HDV.
When is HDV bad?
When it is superimposed on a person who has chronic HBV infection. Can take the envelope it needs, no antibodies to stop him. Results in acute hepatitis, often severe (mortality 5-15%).
Treatment for HDV?
No specific treatment, just try and control HBV.
What kind of virus is HCV? Structural characterisitics?
RNA flavivirus. +ssRNA, icosahedral. Enveloped.
How long is the incubation period for HCV?
6-12 weeks (long).
What percentage of ppl who get infected with HCV go on to develop chronic hepatitis? What is a feared long term complication.
85% go chronic. Of those 20% get cirrhosis. Carcinoma is a feared complication.
How long after exposure is HCV detectable by anti-HCV antibodies?
6-8 weeks after exposure
How is diagnosis of HCV confirmed?
HCV viral PCR.
What are the indications for treatment of HCV?
At least 18 yrs old, HCV RNA detectable in serum, liver bx results showing chronic hep and significant fibrosis, in the setting of compensated liver disease.
What is the response rate to interferon + ribavirin for Hep C genotypes 1 and genotypes 2 and 3?
geno 1: 30-45%. Genos 2-3: 70-80%.
Most ppl in the US have geno 1 :(
What are the new antiviral agents that target Hep C genotype 1?
Protease inhibitors: telaprevir and boceprevir. Inhibits Hepatitis C protease NS3. 60-80% success.
What kind of virus is HEV?
RNA hepevirus.
Who has high mortality with HEV?
pregnant women.
How is HEV transmitted?
Fecal oral, esp waterborne. Endemic in Asia/India/Africa/Central America.
