NEET PG / USMLE – MCQ 25

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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