Hepatitis Viruses Flashcards
Enterically Transmitted
HAV
HEV
Parenterally Transmitted
HBV
HCV
Requires co-infection w/ HBV
HDV
Causes acute hepatitis
HAV
HEV
Can cause chronic hepatitis and lead to hepatocellular carcinoma
HBV (D)
HCV
HAV structure?
Non-enveloped icosahedral capsid. ssRNA+ virus. 1 serotype. Human reservoir.
HEV structure?
Non-enveloped icosadhedral capsid. ssRNA+ virus. Animal reservoir. Developing countries.
HEV infection is most dangerous to what patient population?
Pregnant women. 20% mortality rate.
How is HAV spread?
Fecal-oral route
Early childhood dz with HAV presents how?
Asymptomatic
What are the patient groups at risk for HAV?
- Household or sexual contacts
- Travelers to endemic areas
- Inhabitants of American Indian reservations
What are the patient groups at risk for HAV during an outbreak?
- Diners
- Day care center workers
- Gay men
- IV drug users
What has decreased the number of HAV outbreaks?
Development of vaccine for it.
HBV structure?
Enveloped virus termed Dane particle. Partially dsDNA genome 3200 bp. Hepadnavirus family.
What are the 4 major proteins produced by HBV?
- DNA polymerase (reverse transcriptase)
- HSsAg
- HBcAg/HBeAg
- X Antigen
What does HBsAg do?
Serves as attachment protein. Overwhelms cell membrane causing blebs. These rupture and released into blood as 20 nm particles and filaments. Tons of this in the blood hides actual virus from immune system.
What does HBcAg do?
Capsid protein. HBeAg is a secreted derivative of HBcAg which serves as an important serologic marker.
What does X antigen do?
Influences gene expression and is present in hepatocytes.
Transmission of HBV?
Parenteral route.
Where in the human body is HBV present upon infection?
Blood, semen, and vaj secretions
Where does transcription for HBV take place?
Nucleus. mRNAs are made for the 4 major proteins and a full copy of the genome is also synthesized.
Where is HBV endemic?
China and sub-Saharan Africa. Early infection. (Late infection in US and Europe.)
How many weeks after exposure to HBV will ALT spike?
16 weeks
Chronic HBV patients clinically appear?
Asymptomatic until cirrhosis or HCC appear