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Overview of Hepatitis B Serology

2 main antigens that are used in serology, 3 antigens in total that are found in the hepatitis B virus

Surface antigen (HBsAg)

  • Found on the surface of the hepatitis B virus
  • If we find this antigen in the blood then we know this person is actively infected either acutely or chronically
  • The vaccine for hepatitis B is a modified form of this surface antigen
  • PATIENT IS INFECTIOUS

E antigen (HBeAg)

  • Found between the core and the surface of the hepatitis virus
  • Released during replication – “E antigen escapes”
  • If you find this antigen in the blood, it implies that the person is acutely infected with hepatitis B
  • Levels of this antigen also correlate to how infective the person is, the higher it is, the more infective they are to others

Core antigen (HBcAg)

  • Found in the core of the virus
  • Not found in the blood
  • Not used as a test

3 main antibodies that correspond to the 3 antigens of the hepatitis B virus

Surface antibody (anti-HBs)

  • Demonstrates an immune response to the HBsAg
  • A positive surface antibody could mean
  • RESOLVED PRIOR INFECTION
  • RECEIVED HEPATITIS B VACCINE

E antibody (anti-HBe)

  • Demonstrates that the patient at one point was infected with this virus where the virus was actively dividing and thus releasing the E antibody
  • A positive E antibody could mean
  • RESOLVED PRIOR INFECTION

Core antibody (anti-HBc)

  • 2 versions: IgM and IgG
  • IgM version implies an acute infection
    • High if acute infection (PATIENT IS INFECTIOUS)
  • IgG
    • If positive but HBsAg is negative then this implies
      • RESOLVED PRIOR INFECTION

HBV DNA

  • Direct count of copies of the virus
  • Also called the viral load

HOW TO DETERMINE IF SOMEONE HAS SIMPLY BEEN VACCINATED INSTEAD OF A RESOLVED PRIOR INFECTION?

  • Anti-HBs antibody positive indicating that the patient has developed antibodies against either the surface antigens from a vaccine or from a prior infection (so we know there is immunity in general)
  • Anti-HBc antibody negative indicating that the patient has never been infected with hepatitis B (because remember we never inject the core in a vaccine, just the surface antigen)

What is typical outpatient testing for hepatitis B look like in PublicHealth Ontario? (from PublicHealth Ontario directly)

  • If HBsAg is reactive, further testing for Anti-HBc (Total) is performed automatically
  • If HBsAg is reactive, but the anti-HBc (total) is non-reactive then the specimen is tested using a HBsAg confirmatory test (‘blocking assay’).
  • If the HBsAg and anti-HBc (total) are both reactive and the patient has acute symptoms indicated on the requisition, then the specimen will have the following tests performed:
    • HBeAg
    • anti-HBe
    • anti-HBc IgM