Serology of Hepatitis A, B, C, D, and E

Introduction

• Understanding serology for Hepatitis A, B, C, D, and E
• Important for exams and boards

Hepatitis B Virus (HBV) Serology

Key Antigens and Antibodies

1. Surface Antigen (HBsAg)

   • Located on the virus envelope
   • Positive indicates infection (acute or chronic)

2. Envelope Antigen (HBeAg)

   • Located inside the envelope
   • Positive indicates increased replication and infectivity

3. Core Antigen (HBcAg)

   • Located in the capsid
   • Not directly measured, but antibodies against it are measured

4. Anti-HBs

   • Antibody against surface antigen
   • Positive indicates curing or vaccination

5. Anti-HBc

   • Antibody against core antigen
   • Two types: IgM (acute infection) and IgG (chronic infection)

6. Anti-HBe

   • Antibody against envelope antigen
   • Positive indicates decreased replication and infectivity

7. HBV DNA

   • Indicator of virus replication

Acute Infection

• HBsAg: Positive
• HBeAg: Positive
• HBV DNA: Positive
• Anti-HBs: Negative
• Anti-HBc: Positive (IgM)
• Anti-HBe: Negative

Window Period

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

Recovery

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

Immunization

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

Chronic Infection (replicating)

• HBsAg: Positive
• HBeAg: Positive
• HBV DNA: Positive
• Anti-HBs: Negative
• Anti-HBc: Positive (IgG)
• Anti-HBe: Negative

Chronic Infection (non-replicating)

• HBsAg: Positive
• HBeAg: Negative
• HBV DNA: Negative
• Anti-HBs: Negative
• Anti-HBc: Positive (IgG)
• Anti-HBe: Positive

Hepatitis C Virus (HCV) Serology

Diagnostic Steps

1. Check anti-HCV antibodies (IgG).
   • Positive: Proceed to step 2
2. Check HCV RNA via PCR
   • RNA Positive:
     • Infection active
     • Less than 6 months: Acute
     • More than 6 months: Chronic
   • RNA Negative: Virus cleared

Detection of Fibrosis

• Liver biopsy: Invasive
• FibroSure test: Expensive (~$300)
• APRI score: Cost-effective
  • APRI = (AST / AST standard) / Platelet count * 100
  • APRI > 1.5: Significant fibrosis

Hepatitis D Virus (HDV) Serology

Acute Infection

• HDV RNA: Positive
• Anti-HDV (IgM): Positive
• HD Antigen: Positive in early stages, negative later

Chronic Infection

• HDV RNA: Positive
• Anti-HDV (IgG): Positive
• HD Antigen: Negative

Hepatitis A Virus (HAV) Serology

Acute Infection

• HAV RNA: Positive (via blood or stool)
• 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

• HEV RNA: Negative
• Anti-HEV (IgG): Positive for 2-3 years, then declines

Special Note

• Pregnancy: High risk of fulminant hepatitis, requires liver transplant

Conclusion

• Covered serology for hepatitis A, B, C, D, and E
• Detailed understanding required for exams and clinical practice

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