Collection of Medicine MCQs (Cardiovascular system) for medical students. Concept based MCQs with detailed explanations which help students to gain valuable insights and gain an edge in competitive examinations. More than just answering MCQs, the explanations will improve the knowledge and understanding about the conditions discussed. Also useful for MD students who are preparing for Superspeciality entrance examinations. Medicine MCQs - Cardiovascular System Kindle Edition: Click Here for a Preview. Comments and suggestions are most welcome.

A 26-year-old man with HIV infection comes to the physician for a follow-up examination. Six months ago, he had an acute infection characterized by jaundice. Current medications include zidovudine (AZT), delavirdine, and ritonavir. Laboratory studies 6 months ago and today show:

6 months ago Today
Total bilirubin 2.5 mg/dL  3.5 mg/dL
ALT 68 U/L  45 U/L
Hepatitis B surface antigen (HBsAg) positive positive
Hepatitis B e antigen (HBeAg) positive negative
IgM anti-hepatitis B core antigen (anti-HBcAg) positive negative
Anti-HBsAg negative negative
Anti-HBeAg negative positive
Anti-HBcAg positive positive

This patient’s infection is most likely to resolve when he develops antibodies to which of the following?

A. Cytotoxic T lymphocytes
B. HBcAg
C. HBeAg
D. HBsAg
E. Natural killer cells

Correct answer : D. HBsAg

Lets review the various antigens and antibodies in viral hepatitis B:

  • HBsAg – Hepatitis B surface antigen. Seen in acute infection. Persistence more than 6 months indicates chronic infection.
  • Anti-HBs – Antibody to HBsAg. Implies previous infection / vaccination. In case of previous infection, Anti-HBc is also present usually. But in case of vaccination, Anti-HBc is not present.
  • HBcAg – Hepatitis B core antigen – Not seen in blood
  • Anti-HBc – Antibody to HBcAg. Appears early in the disease.  Reaches a high titre which then subsides, but persists. It is of 2 types – IgM and IgG. IgM appears first, IgG later.
  • HBeAg – Appears only transiently. Indicates active replication of virus in liver.
  • Anti-HBe – Antibody to HBeAg. Indicates that low level replication of virus is taking place / HBV-DNA has integrated into host hepatocyte DNA
  • Chronic infection is indicated by presence of HBsAg and anti-HBc (IgG)
So now let us look at the question. 6 months back, he had active infection (HBsAg) with active replication of virus in liver (HBeAg). Now he has chronic hepatitis (HBsAg with anti-HBc IgG) with low level replication of virus (Anti-HBe).
The infection would have resolved by the time he develops antibody to HBsAg.

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