Hepatitis Be Antigen

The Hepatitis B e antigen (HBeAg, HBV e antigen) assay is used with other serologic markers and HBV DNA testing to assess replicative activity and infectiousness in persons with hepatitis B virus infection. In chronic disease, it supports staging and guides decisions on when to initiate therapy, how to monitor during treatment, and how to document response, including HBeAg loss and seroconversion. Detection or clearance of HBeAg also contributes to infection‑control planning and transmission risk counseling. This assay is not intended for the diagnosis of acute hepatitis B infection.

Hepatitis B virus (HBV) is a DNA virus that causes both acute and chronic hepatitis worldwide and is associated with substantial morbidity. Transmission occurs through blood and body fluids, including percutaneous exposure, sexual contact, and perinatal spread. Populations at increased risk include healthcare personnel with blood exposure, hemodialysis patients, people who inject drugs, individuals with multiple sexual partners, and infants born to HBV‑infected mothers. HBV expresses several antigens relevant to laboratory testing: HBsAg (surface), HBcAg (core), and HBeAg, a secreted product of the precore/core region. In acute infection, HBeAg appears at about the same time as, or shortly after, HBsAg and usually clears earlier. Its presence signifies active viral replication and high infectivity; HBeAg‑positive serum is several‑fold more infectious than HBsAg‑positive/HBeAg‑negative serum. Persistence of HBeAg beyond approximately 8–10 weeks suggests evolution toward chronic infection, whereas loss of HBeAg with the emergence of anti‑HBe generally indicates reduced replicative activity and therapeutic response. In chronic hepatitis B, reappearance of HBeAg can indicate viral reactivation, frequently in the context of immunosuppression. Mutations in the precore or basal core promoter region may prevent HBeAg production, leading to HBeAg‑negative chronic hepatitis B with ongoing infectivity and replication that are demonstrable by HBV DNA testing. Interpretation of HBeAg should be integrated with HBsAg, anti‑HBe, anti‑HBc (IgM and total), and HBV DNA results. This assay is not intended for diagnosis of acute hepatitis B infection.