Microbiology of the Hepatitis Viruses Flashcards
What group of people living in the U.S. accounts for greater than 50% of Americans living with chronic HBV?
Asian and Pacific islanders, most likely acquired in-utero from parents that were not originally from the U.S.
- hepatocellular carcinoma is leading cause of CANCER death in this population.
What type of virus is Hepatitis A (HAV)? (SKETCHY)
Picornavirus (+ ss RNA) naked icosahedral virus.
Does infection with HAV confer lifelong immunity?
YES :)
What type of virus is Hepatitis E (HEV)?
Hepeviridae (+ ss RNA) naked icosahedral virus.
*resembles Calicivirus
What HEV genotype is common in the U.S. and the world, respectively?
U.S.= genotype 3; porcine zoonotic disease World= Asia, Middle East, Africa, and Central America.
What group of people must you be most concerned with acquiring HEV?
- pregnant women (associated with fulminant hepatitis; liver failure with massive liver necrosis).
What is the Hepatitis B surface antigen (HBsAg)?
surface glycoprotein, which has 3 initiation codons:
1. small
2. medium (Dane particle)= infectious particle
3 large
*combination of these form the HBsAg
What happens once antibody is generated against HBsAg?
you have immunity against infection/reinfection :)
*antibody will remove small, medium, and large antigens/particles
When will antibody against HBsAg (HBsAB) be detected in the blood?
Not until the HBV infection is resolved!
What are the 2 CORE antigens?
- HBcAg= core
- HBeAg= envelope (secreted form of the core protein)
* they will each induce their own antibody response
What is Hepatitis D (HDV)?
subviral particle that uses HBsAg to form an envelope and allow spread from cell to cell.
Does HDV superinfection with HBV increase the severity of HBV?
YES
What type of viruses are Hepatitis C and G?
Flaviviruses= (+ SS RNA virus) also Yellow Fever, Dengue, and West Nile (however these are transmitted by mosquito, whereas HCV and HGV are NOT).
What is HGV also called?
GBV-C
Are many people with HCV also co-infected with HIV?
YES (30-50%)
*worsens HIV infection
What does HGV infection do to HIV co-infection?
slows HIV progression
How is HGV acquired?
via blood transfusions only
What forms of hepatitis can be asymptomatic?
all except HDV
What is the incubation period for Hepatitis B,C, and D viruses?
6 weeks to 6 months.
What is the incubation period for Hepatitis A and E?
about 4 weeks.
Is jaundice occurring as a result of HBV more or less likely to occur as a patient gets older?
MORE likely
Are you more or less likely to have chronic HBV infection if you are an infant?
MORE (90%), but more likely to be asymptomatic compared to adults (6%), whom are more likely to be symptomatic. AKA inverse relationship.
*** What is CHRONIC immune TOLERANT HBV?
- persistently NORMAL hepatic aminotransferase levels - high levels of circulation HBeAg and HBV DNA.
- usually infected prenatally (NEWBORNS).
*** What is HBeAg+ immune ACTIVE CHRONIC HBV?
- HBsAg is positive longer than 6 months.
- HBeAg is positive, anti-HBe is negative.
- High levels of HBV DNA in serum (>20,000 IU/mL).
- persistent or intermittent ELEVATION in hepatic aminotransferase level.
*** What is CHRONIC INACTIVE carrier of HBV?
- HBsAg positive for longer than 6 months.
- HBeAg negative, anti-HBe positive.
- serum HBV DNA LESS than 2,000 IU/mL.
- persistently NORMAL hepatic aminotransferase levels.
- AKA virus is there but not as high.
*** What is HBeAg-negative; immune REACTIVATION?
SAME as CHRONIC inactive carrier of HBV except:
- serum HBV DNA GREATER than 2,000 IU/mL.
- persistently ELEVATED or intermittently normal hepatic aminotransferase levels.
- associated with core promoter mutations (takes longer so will be seen in older pts).
Do most people with HCV viremia (HCV RNA in the blood) have a chronic infection?
YES (with antibody response)
How do you diagnose HAV?
- ELISA for alpha-HAV IgM for acute infection.
- alpha- HAV IgG indicates prior exposure and protective immunity.
- increased AST and ALT
How do you diagnose HEV?
no clinical test available but the markers would be the same as HAV
What is TOTAL anti-HBc?
IgM + IgG antibodies against HBc
** What antibody confers immunity in HBV?
anti-HBs (HBsAB= IgG)
Why don’t you see anti-HBs in serum during the window period?
because even though it is present, it is bound to HBsAg in the blood, therefore FREE anti-HBs is not detected for a few weeks on serology until more is made.
What does HBeAg indicate?
Infectivity
*remember E for envelope and when you send a letter (aka transmission) you need an envelope.
Doe antibody against HBe indicate that the virus is cleared?
NO (only HBs antibody).
What does HBc antibody (IgM or IgG) indicate?
just current or previous exposure to HBV.
*IgM= acute infection
Are there tests available for HDV?
NO, just research settings.
With co-infection of HDV and HBV, will antibodies (IgM and IgG) drop over time as acute infection resolves?
YES
With superinfection of HDV and HBV, will antibodies drop over time?
NO, high titers of anti-HDV remain high as chronic infection of HBV persists.
How do you test for whether a pt is acutely or chronically infected with HCV?
You can’t. All you can know is that they had an antibody response and were previously infected.
*You can test for HCV-RNA, but again all that tells you is that you have an active infection, not whether it is acute or chronic. If this is negative, but anti-HCV is positive, repeat in 6 months. If it is again negative, studies now say you can assume the infection has been resolved.
So, what does +anti-HCV, but - HCV RNA test result mean?
no current HCV infection, but follow up in 6 months to make sure HCV RNA is still negative.
