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|
This patient’s infection is most likely to resolve when he develops antibodies to which of the following?
A. Cytotoxic T lymphocytes
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)