Quiz week 12

This quiz was relatively easy. Those who did not get this right should be working hard to understand what the ABIM would accept as a reasonable answer.

Q1. Which one of the following serologic results is representative of a patient vaccinated with hepatitis B vaccine 2 years ago.

1. HBSAg+ve, HBCAb+ve, HBSAb+ve, HBEAg+ve, HBEAb+ve
2. HBSAg -ve, HBCAb+ve, HBSAb+ve, HBEAg+ve, HBEAb+ve
3. HBSAg -ve,, HBCAb -ve, HBSAb+ve, HBEAg -ve, HBEAb+ve
4. HBSAg -ve, HBCAb -ve, HBSAb+ve, HBEAg -ve, HBEAb -ve
5. HBSAg+ve, HBCAb -ve, HBSAb +ve, HBEAg-ve, HBEAb -ve

Answer is Choice 4. The vaccine for hepatitis B has Surface antigen particles (Australia antigen). If tested within the first couple of weeks, one will detect it in the blood. Thereafter, the antibody response starts and the antigen is cleared from serum and the antibody prevails. The first antibody to appear in any antibody response is IgM type. This is the predominant antibody for 2-3 months and then IgG appears and remains long term. My family name is Malhotra and first name is Gaurav - I remember that the name Malhotra came into existence first and then came Gaurav. You can evolve your own system to memorize this).

In the case of a vaccinated person, there is no exposure to C antigen or E antigen. This is why neither these antigens nor their antibodies are seen.

Q2. The presence of which of the following is associated with high infectivity of hepatitis B?

1. HBSAg (Surface antigen)
2. HBCAb (Core antibody)
3. HBEAb (E antibody)
4. HBSAb (Surface antibody)
5. HBEAg (E antigen)

The answer is Choice 5. (HBEAg (E antigen) ) HBEAg is a measure of the rapidity of replication of the virus in the body. Its existence signifies an active process of replication and thus - a high viral load. These patients are highly infective.