7 Hepatitis B

Question 1

what genome does hep A have

Answer 1

RNA

Question 2

what is the RNA like in hep A

Answer 2

+ve single stranded RNA

Question 3

how is hep A transmitted

Answer 3

faecal-oral route of transmission

• Entry via contaminated food or water
• Excreted in faeces

Question 4

what are the viral and serological markers of infection

Answer 4

ALT increases - acute hep
Virus replicate in small bowel into blood stream to liver and release in faeces
When reach liver = ill but before not detected in blood = blood donor = transmit hep
IgM AB disappear
IgG response slower but then persists

Question 5

Hepatitis A Virus – Consequences of Infection

Answer 5

• Asymptomatic infection
• Acute icteric hepatitis
• Fulminant hepatitis (rare)

Question 6

Prevention of hepatitis A

Answer 6

Care with food and water
Vaccination
> Whole killed virus

Question 7

what is hep B genome

Answer 7

Unusual genome – partially ds = family is called Hepadnavirus
compact– encodes few proteins

Question 8

what forms around DNA in hep B

Answer 8

Core forms capsid around DNA

Question 9

what are the 6 diagnostic markers for hep B

Answer 9

HBsAg; HBcAg; HBeAg

Anti-HBs; Anti-HBc; Anti-HBe

Question 10

HBV replication

Answer 10

• Enters cell as partially ds DNA
• 2nd strand is completed covalently closed circular DNA (cccDNA)
• Synthesis and packaging of pregenomic RNA
• Reverse transcription of pregenomic RNA within capsid partially dsDNA

Question 11

Natural History of HBV Infection – Adults and neonates

Answer 11

acute infection:

• subclinical infection
• acute iceteric hep
• fulminant hep (1%)
• chronic infection (5-10%) = healthy or chronic hep or cirrhosis ca liver

Question 12

what is Cirrhosis ca liver

Answer 12

normal liver architecture replaced by fibrous (increased risk in hep b – transforming virus)

Question 13

what is a chronic

Answer 13

virus continually replicating

Question 14

what causes most chronic HBV in UK

Answer 14

imported

Question 15

Hepatitis B: Modes of Transmission

Answer 15

• Perinatal (mother to baby at birth)
• Sexual
• Parenteral (exposure to someones blood - unsafe injections and transfusion)

Question 16

Acute hepatitis B detection

Answer 16

HBsAg positive – doesn’t say when got infected
IgM anti-HBc positive - IgM AB as marker of recent infection – as come and go
Acute infection will either resolve or become chronic

Question 17

Resolved acute HBV infection

Answer 17

If resolved = Would have lost surface antigen = surface antigen negative 
HBsAg disappears (may take up to 6 months)

Question 18

what is a marker of past infection

Answer 18

anti-HBc (IgG)

Question 19

what may arise from result of vaccination

Answer 19

anti-HBs

Question 20

Chronic HBV infection

Answer 20

Defined as persistence of HBsAg for > 6 months

Question 21

Chronic HBV infection - HBeAg positive

Answer 21

• high infectivity eg needlestick

- increased risk of inflammatory liver disease

Question 22

Chronic HBV infection - Anti-HBe positive

Answer 22

• low infectivity

- low risk of CLD

Question 23

Prevention of HBV infection

Answer 23

• Simple precautions
• Hepatitis B immunoglobulin (passive immunisation)
• Hepatitis B vaccine (active immunisation)
• Recombinant HBsAg – induces anti-HBs

Question 24

what are the risk groups that should be vaccinated

Answer 24

• Healthcare workers
• Baby for infected mother
• Sexual partners

Question 25

what must healthcare workers that perform EPP be tested for

Answer 25

• Be tested for HBsAg
• If HBsAg +ve, check for HBeAg
• If HBeAg +ve, BANNED from EPPs