Serological Diagnosis of Hepatitis A and Hepatitis B virus infection

Serological Diagnosis of Hepatitis A virus Infection

Hepatitis A cannot be distinguished from other types of viral hepatitis on the basis of clinical or epidemiologic features alone.

Serology is the primary method for the laboratory diagnosis of Hepatitis A Virus infection. IgM anti-HAV is the Reliable marker of acute infection with Hepatitis A Virus. Virtually all patients with acute hepatitis A have detectable IgM anti-HAV.

Timeline for Hepatitis A Virus Infection

 Laboratory testing for IgM anti-HAV is typically positive at the time of onset of symptoms (detectable 5/6 days prior to onset of system) . It remains positive for 3-6 months after primary infection.

The antibody test for total anti-HAV measures both IgG anti-HAV and IgM anti-HAV. Persons who are total anti-HAV positive and IgM anti-HAV negative i.e. presence of IgG anti-HAV in the absence of IgM anti-HAV indicates past infection or vaccination rather than acute infection.

Serological Diagnosis of Hepatitis B virus Infection

HBsAg and hepatitis B e antigen (HBeAg) are the first markers identified in the serum of patients acutely infected with HBV.

Detection of Antigen:

1.       HBsAg (also called Australia antigen or hepatitis-associated antigen):

Timeline for Acute Hepatitis B Virus Infection

 HBsAg generally appears before symptom onset and peaks during overt disease. In patients who successfully clear the HBV infection and do not progress to the chronic carrier stage, HBsAg typically is undetectable 4 to 6 months after infection

2.       HBeAg:
HBeAg, a soluble protein which is contained in the core of Hepatitis B Virus. HBeAg is generally considered to be a marker of HBV replication and infectivity.

Detection of Antibody

1.       IgM anti-HBc (IgM class antibody to HBcAg)
The first antibody to appear is IgM antibody to hepatitis B core antigen (IgM anti-HBc). The presence of the IgM anti-HBc antibody is diagnostic of acute HBV infection. IgM anti-HBc is first detectable in the serum shortly before the onset of symptoms at a time generally concurrent with the onset of elevated transaminase levels.

2.       IgG anti-HBc (IgG class antibody to HBcAg)
The presence of IgG anti-HBc indicates that the patient has a history of infection with HBV. Within several weeks, the IgM anti-HBc disappears, and IgG anti-HBc is detected. IgG anti-HBc may remain present for life.

Timeline for Chronic Hepatitis B Virus Infection

3.       Anti-HBs
The presence of anti-HBs is likely to be protective against repeated HBV exposure, and the anti-HBs may persist for life.

4.       Anti-HBe
When viral replication slows and infectivity declines, the HBeAg disappears and antibodies to hepatitis B e antigen (anti-HBe) may be detected. HBeAg to anti-HBe seroconversion occurs early in patients with acute infection, before HBsAg to anti-HBs seroconversion. Anti-HBe may persist for years.