Serology of Hepatitis (A, B, C, D, E)

Jun 16, 2024

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Serology of Hepatitis (A, B, C, D, E)

Introduction

  • Importance of understanding hepatitis serology for exams and clinical practice.
  • Focus on Hepatitis B virus (HBV) antigens and antibodies.

Hepatitis B Virus (HBV) Serology

Key Antigens

  1. Surface Antigen (HBsAg) (Envelope)
    • On the outer surface of the virus.
    • Positive result indicates infection (acute or chronic).
  2. Envelope Antigen (HBeAg)
    • Between envelope and capsid.
    • Positive result indicates increased replication and infectivity.
  3. Core Antigen (HBcAg) (Capsid) (Not measured directly)
    • Antibodies against core antigen are measured.

Key Antibodies

  1. Anti-HBs (against Surface Antigen) (cure or vaccination)
    • Positive result indicates cure or successful vaccination.
  2. Anti-HBc (against Core Antigen)
    • IgM: acute infection.
    • IgG: chronic infection.
  3. Anti-HBe (against Envelope Antigen)
    • Positive result indicates decreased replication and infectivity.

HBV DNA

  • Positive result indicates increased replication and infectivity.

Stages of Infection

Acute Infection

  • HBsAg: Positive
  • HBeAg: Positive
  • HBV DNA: Positive
  • Anti-HBs: Negative (takes ~6 months to appear)
  • Anti-HBc IgM: Positive
  • Anti-HBe: Negative

Window Period

  • HBsAg: Negative
  • HBeAg: Negative
  • HBV DNA: Negative or low
  • Anti-HBs: Negative
  • Anti-HBc: Positive (IgM and IgG mix)
  • Anti-HBe: Negative

Recovery

  • HBsAg: Negative
  • HBeAg: Negative
  • HBV DNA: Negative
  • Anti-HBs: Positive
  • Anti-HBc IgG: Positive
  • Anti-HBe: Not applicable

Immunized

  • HBsAg: Negative
  • HBeAg: Negative
  • HBV DNA: Negative
  • Anti-HBs: Positive
  • Anti-HBc: Negative

Chronic Infection

Replicative (replicating)
  • HBsAg: Positive
  • HBeAg: Positive
  • HBV DNA: Positive
  • Anti-HBs: Negative
  • Anti-HBc IgG: Positive
  • Anti-HBe: Negative
Non-Replicative (not replicating)
  • HBsAg: Positive
  • HBeAg: Negative or decreased
  • HBV DNA: Negative or low
  • Anti-HBs: Negative
  • Anti-HBc IgG: Positive
  • Anti-HBe: Positive

Hepatitis C Virus (HCV) Serology

  • Initial test: Anti-HCV antibodies (IgG)
  • Positive result: Check HCV RNA by PCR
    • If HCV RNA is positive, patient is infected
    • If HCV RNA is negative, patient has cleared the virus

Acute vs Chronic HCV

  • Acute: HCV RNA positive for < 6 months
  • Chronic: HCV RNA positive for > 6 months

Fibrosis Testing

  • Options: Liver biopsy, FibroSure test, APRI score (AST to platelet ratio index)
    • APRI > 1.5 indicates significant fibrosis

Hepatitis D Virus (HDV) Serology

  • Requires HBV co-infection

Acute Infection

  • HDV RNA: Positive
  • HDV antigen: Positive
  • Anti-HDV IgM: Positive

Chronic Infection

  • HDV RNA: Positive
  • HDV antigen: Negative
  • Anti-HDV IgG: Positive

Hepatitis A Virus (HAV) Serology

  • Acute infection: HAV RNA positive, Anti-HAV IgM positive
  • Past exposure/immunization: HAV RNA negative, Anti-HAV IgG positive

Hepatitis E Virus (HEV) Serology

Acute Infection

  • HEV RNA: Positive
  • Anti-HEV IgM: Positive

Past Exposure/Cleared Infection

  • HEV RNA: Negative
  • Anti-HEV IgG: Positive (only persists for 2-3 years)

Additional Info

  • HEV in pregnancy increases risk of fulminant hepatitis and death.

Summary

  • Detailed overview of serology for hepatitis viruses A, B, C, D, and E.
  • Key markers and their interpretations for diagnosing different types and stages of hepatitis infections.

Note

  • Hepatitis A and B have vaccines.
  • Hepatitis C and E do not have vaccines.