Hepatitis B virus surface antigen (HBsAg) | Antibodies

Hepatitis B virus Consists of a nucleus and a membrane. Its genome contains double-stranded DNA. The infection is transmitted through blood or sexual contact. Incubation period - about 70 days (40-160 days).

Hepatitis B virus surface antigen (HBsAg) Is part of the outer membrane of the virus. It is known as the "Australian Antigen" and is one of the first markers to appear in the blood at the end of the incubation period (in parallel with the detection of viral DNA in the blood) and 2 weeks before the appearance of HBcor-IgM (antibody to hepatitis B antigen).

In response to HBsAg, the body produces protective antibodies (Anti-HBs), which are detected 1-4 months after the elimination of HBsAg and their appearance indicates a favorable course of hepatitis B - the end of virus replication and the recovery period. This period is called the "serological window" period, when only common antibodies to the hepatitis B virus nuclear antigen (anti-HBcAg) are detected. The duration of the window phase can vary up to 1 year, depending on the condition of the patient's immune system. In the chronic course of hepatitis B infection, it is possible to detect the surface antigen and antibodies against it in parallel. Detection of anti-HBs antibodies in parallel with the detection of HBsAg in the acute phase of hepatitis B indicates a poor prognosis of the disease.

In addition, common antibodies to the HBV surface antigen (anti-HBs) are produced in response to vaccination with genetically modified HbsAg and provide effective protection against HBV infection (average 5-15 years). Over time, the level of protective antibodies decreases, therefore, it is necessary to further monitor the vaccination every 5 years and revaccinate if necessary.

Passive transfer of anti-HBs antibodies is possible during transfusion.

Determination of the level of these antibodies is used to monitor the effectiveness of vaccination, to control the level of protective immunity, to determine the need for revaccination, and to manage HbsAg-negative patients with antibodies to HBcorAg (nuclear antibody to hepatitis B).

Simultaneous detection of antibodies against HBsAg and HBcorAg allows:

• Differential diagnostics between vaccination results and virus infection. Only HBsAg antibodies are detected after vaccination and no HBcorAg antibodies are detected. Conversely, detection of antibodies to HBcorAg alone indicates a previously transmitted HBV infection (in the absence of other markers);
• Diagnosis of acute hepatitis B in the "serological window" phase or delayed immune response: No antibodies to HBsAg and HBsAg have been detected, but antibodies to HBcorAg have been detected. In this case, antibodies to HBeAg (hepatitis B virus e antigen) are also detected;
• Diagnosis of the recovery phase of acute hepatitis: HBsAg is not detected, antibodies to HbsAg, HbcorAg and HbeAg are detected simultaneously.

When should we take the test?

• Monitoring the progress of acute hepatitis B infection;
• Monitoring the effectiveness of immunization programs;
• Formation of immunity after hepatitis B infection or immunization.

How to prepare for the test?

No special preparation is required for the test.

Research material

Venous blood

Possible interpretation of the results

Positive result:

• Successful vaccination against hepatitis B;
• Acute hepatitis B, recovery phase;
• Chronic hepatitis B;
• Passive transmission during transfusion.

Negative result:

• The effect of vaccination is not achieved;
• History of hepatitis B (in the absence of other markers of hepatitis B, especially common antibodies to HBcorAg).
• Acute hepatitis B (incubation or acute periods) is not excluded;
• Chronic hepatitis B with high infection is not excluded.

Resources

https://www.synevo.bg/anti-hbs/
https://spravochnik.synevo.ua/ru/id1555/id1563.html