Microbiology of the Hepatitis Viruses Flashcards Preview

Gastrointestinal 1 > Microbiology of the Hepatitis Viruses > Flashcards

Flashcards in Microbiology of the Hepatitis Viruses Deck (40)
Loading flashcards...
1
Q

What group of people living in the U.S. accounts for greater than 50% of Americans living with chronic HBV?

A

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.

2
Q

What type of virus is Hepatitis A (HAV)? (SKETCHY)

A

Picornavirus (+ ss RNA) naked icosahedral virus.

3
Q

Does infection with HAV confer lifelong immunity?

A

YES :)

4
Q

What type of virus is Hepatitis E (HEV)?

A

Hepeviridae (+ ss RNA) naked icosahedral virus.

*resembles Calicivirus

5
Q

What HEV genotype is common in the U.S. and the world, respectively?

A
U.S.= genotype 3; porcine zoonotic disease
World= Asia, Middle East, Africa, and Central America.
6
Q

What group of people must you be most concerned with acquiring HEV?

A
  • pregnant women (associated with fulminant hepatitis; liver failure with massive liver necrosis).
7
Q

What is the Hepatitis B surface antigen (HBsAg)?

A

surface glycoprotein, which has 3 initiation codons:
1. small
2. medium (Dane particle)= infectious particle
3 large
*combination of these form the HBsAg

8
Q

What happens once antibody is generated against HBsAg?

A

you have immunity against infection/reinfection :)

*antibody will remove small, medium, and large antigens/particles

9
Q

When will antibody against HBsAg (HBsAB) be detected in the blood?

A

Not until the HBV infection is resolved!

10
Q

What are the 2 CORE antigens?

A
  1. HBcAg= core
  2. HBeAg= envelope (secreted form of the core protein)
    * they will each induce their own antibody response
11
Q

What is Hepatitis D (HDV)?

A

subviral particle that uses HBsAg to form an envelope and allow spread from cell to cell.

12
Q

Does HDV superinfection with HBV increase the severity of HBV?

A

YES

13
Q

What type of viruses are Hepatitis C and G?

A

Flaviviruses= (+ SS RNA virus) also Yellow Fever, Dengue, and West Nile (however these are transmitted by mosquito, whereas HCV and HGV are NOT).

14
Q

What is HGV also called?

A

GBV-C

15
Q

Are many people with HCV also co-infected with HIV?

A

YES (30-50%)

*worsens HIV infection

16
Q

What does HGV infection do to HIV co-infection?

A

slows HIV progression

17
Q

How is HGV acquired?

A

via blood transfusions only

18
Q

What forms of hepatitis can be asymptomatic?

A

all except HDV

19
Q

What is the incubation period for Hepatitis B,C, and D viruses?

A

6 weeks to 6 months.

20
Q

What is the incubation period for Hepatitis A and E?

A

about 4 weeks.

21
Q

Is jaundice occurring as a result of HBV more or less likely to occur as a patient gets older?

A

MORE likely

22
Q

Are you more or less likely to have chronic HBV infection if you are an infant?

A

MORE (90%), but more likely to be asymptomatic compared to adults (6%), whom are more likely to be symptomatic. AKA inverse relationship.

23
Q

*** What is CHRONIC immune TOLERANT HBV?

A
  • persistently NORMAL hepatic aminotransferase levels - high levels of circulation HBeAg and HBV DNA.
  • usually infected prenatally (NEWBORNS).
24
Q

*** What is HBeAg+ immune ACTIVE CHRONIC HBV?

A
  • 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.
25
Q

*** What is CHRONIC INACTIVE carrier of HBV?

A
  • 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.
26
Q

*** What is HBeAg-negative; immune REACTIVATION?

A

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).
27
Q

Do most people with HCV viremia (HCV RNA in the blood) have a chronic infection?

A

YES (with antibody response)

28
Q

How do you diagnose HAV?

A
  • ELISA for alpha-HAV IgM for acute infection.
  • alpha- HAV IgG indicates prior exposure and protective immunity.
  • increased AST and ALT
29
Q

How do you diagnose HEV?

A

no clinical test available but the markers would be the same as HAV

30
Q

What is TOTAL anti-HBc?

A

IgM + IgG antibodies against HBc

31
Q

** What antibody confers immunity in HBV?

A

anti-HBs (HBsAB= IgG)

32
Q

Why don’t you see anti-HBs in serum during the window period?

A

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.

33
Q

What does HBeAg indicate?

A

Infectivity

*remember E for envelope and when you send a letter (aka transmission) you need an envelope.

34
Q

Doe antibody against HBe indicate that the virus is cleared?

A

NO (only HBs antibody).

35
Q

What does HBc antibody (IgM or IgG) indicate?

A

just current or previous exposure to HBV.

*IgM= acute infection

36
Q

Are there tests available for HDV?

A

NO, just research settings.

37
Q

With co-infection of HDV and HBV, will antibodies (IgM and IgG) drop over time as acute infection resolves?

A

YES

38
Q

With superinfection of HDV and HBV, will antibodies drop over time?

A

NO, high titers of anti-HDV remain high as chronic infection of HBV persists.

39
Q

How do you test for whether a pt is acutely or chronically infected with HCV?

A

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.

40
Q

So, what does +anti-HCV, but - HCV RNA test result mean?

A

no current HCV infection, but follow up in 6 months to make sure HCV RNA is still negative.