Hepatitis B markers: decoding antigens and antibodies (HBsAg, HBeAg, anti-HBs)
Diagnosis of hepatitis B virus (HBV) is a complex detective process. Unlike many other infections, where a single test is sufficient, a whole panel of markers is used to assess the condition of the pancreas or liver in hepatitis B. The study is carried out using the method ELISA (enzyme-linked immunosorbent assay), detecting in the blood both specific proteins of the virus itself (antigens) and the immune system response (antibodies).
Let's analyze what each indicator on the laboratory form means and what their presence indicates.
1. Virus antigens (foreign proteins)
Antigens are the structural parts of the virus that first appear in the body and indicate the presence of an infection.
HBs antigen (HBsAg) — surface antigen of the virus. This is the main marker that appears in the blood at the end of the incubation period (before the first symptoms). This indicator is not constant, since the protein structure of the virus is often subject to mutations. The presence of HBsAg indicates that a person is infected (acute or chronic form).
HBe antigen (HBeAg) — core replication antigen. Appears in the serum of patients with acute hepatitis and chronic active hepatitis from the end of the incubation period to the end of the replication phase. It directly indicates active reproduction (replication) of the virus and high infectiousness of the patient.
Importantly: HBeAg is not detected in infection with pre-core mutants of the HBV virus, as well as in HDV superinfection (Delta hepatitis).
HBcor antigen (HBcAg) — nuclear antigen. This protein is found exclusively inside liver cells (hepatocytes) and does not enter the blood free. Therefore, in laboratory tests in blood serum it not investigated(instead, they look for antibodies to it).
2. Antibodies (the body's protective shield)
Antibodies (immunoglobulins) IgM and IgG) are produced by the immune system in response to the appearance of viral antigens. They show what stage the disease is at and whether immunity has been formed.
Antibodies to HBs (Ab HBs / anti-HBs) of IgM and IgG class These are antibodies to the surface antigen. They appear at the end of the acute period of hepatitis or 3–8 months after infection. These antibodies are able to persist in the body 10 years or more. Most importantly: they testify to presence of immunity (after a previous illness or successful vaccination). It is anti-HBs that are used as the main criterion for the effectiveness of vaccine prophylaxis.
Antibodies to HBe (Ab HBe / anti-HBe) of IgM and IgG class These antibodies are produced against the internal HBe protein. They appear from the 2nd to the 3rd week of the jaundice period and can persist in the blood for 2 to 5 years. The appearance of these antibodies is a good sign indicating the beginning of non-replicative phase (the virus is suppressed and stops actively reproducing).
Who needs such research?
A comprehensive ELISA analysis is prescribed in the following cases:
With symptoms of liver damage (jaundice, dark urine, pain in the right hypochondrium, increased ALT/AST).
For screening at-risk groups and pregnant women.
Before vaccination (to check for latent infection).
After a certain time after vaccination (to assess the level of protective antibodies
anti-HBs).To monitor the effectiveness of treatment for chronic hepatitis B.
Pay attention! Only an infectious disease specialist or gastroenterologist can correctly interpret the combination of antigens and antibodies, establish an accurate diagnosis (acute, chronic, past hepatitis or chronic carrier) and prescribe treatment.
Head of the clinical diagnostic laboratory of Medi Lab Plus LLC, Master of Biochemistry with over 15 years of management experience. Monitors compliance of research with international EUCAST protocols and ISO 15189 standard. Acts as a medical editor of the site materials. More details…