Understanding the Hepatitis B e-Antigen (HBeAg)

HBeAg stands for hepatitis B e-antigen. This antigen is a protein from the hepatitis B virus that circulates in infected blood when the virus is actively reproducing.

If you are HBeAg positive, it means the antigen is present in your blood. This HBeAG test result suggests that a person is infectious and is able to spread the virus to other people.

What HBeAg Test Results Mean

A positive test for the hepatitis B e-antigen (HBeAG) means that there is an active infection with the hepatitis B virus, likely in someone with chronic hepatitis B. The virus is actively multiplying.

Anyone who is in contact with your blood without protection may be at risk of contracting hepatitis B from you.

If the HBeAG test result is negative, it means that the e-antigen is no longer present in someone diagnosed with hepatitis B. However, it is possible for the virus to keep replicating and for the HBeAG-negative person to require treatment. They're likely to require careful monitoring.

HBeAg Tests During Pregnancy

Pregnant people are screened for a different antigen, called the hepatitis B surface antigen (HBsAg). It also shows an active infection with hepatitis B.

If the HBsAG test is positive, the HBeAg test may be done along with other tests. These tests may include the HBV DNA concentration (or viral load) test and the alanine aminotransferase (ALT) test. The ALT focuses on a specific enzyme to assess for liver function.

If the HBeAg test is positive, the Centers for Disease Control and Prevention (CDC) recommends that the person be referred to a specialist immediately for care during the rest of their pregnancy.

Whether or not the HBeAg is positive and the virus active, the newborn will need to be treated with both passive and active immunization (both HBIG and Hepatitis B vaccine) to keep them from becoming infected. 

HBeAg in Chronic Hepatitis B

People with chronic hepatitis B can show seroconversion. This means the levels of HBeAg drop until they're no longer detected while levels of anti-HBe antibodies develop. This is seen as a good sign for prognosis and an indication that your treatment may be working successfully.

Understanding HBeAG and HBsAG

An antigen is a protein that stimulates an immune system response, causing your body to produce antibodies to fight invaders.

In hepatitis B, it's common to test for the hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg). These antigens are attached to the inside and the outside of the virus. While HBsAg can be detected directly in the blood, HBcAg can only be detected by testing for hepatitis B core antibodies (anti-HBc).

The hepatitis B e-antigen (HBeAG) is different. It's a protein that the virus manufactures and secretes. It isn't circulating while attached to the virus but instead is free in your bloodstream and tissues.

The HBeAG is produced when the virus is actively multiplying, so it's a sign that you have an active infection and people in contact with your blood and body fluids are at risk of contracting the virus.

Interestingly, there are strains of hepatitis B virus that don't produce HBeAg. People who acquire the infection in the Middle East and Asia may have one of these strains. In this case, a negative HBeAg test has little meaning. They can have an active Hepatitis B infection without a positive HBeAg test.