Occult hepatitis B virus infection with positive hepatitis B e antigen.

BACKGROUND: Hepatitis B e antigen (HBeAg) is a marker to indicate active replication of hepatitis B virus (HBV). Occult HBV infection (OBI), referred to persistence of HBV DNA in serum and/or liver without detectable serum hepatitis B surface (HBsAg), usually has low HBV DNA levels. The presence of HBeAg in OBI is unusual.

METHODS: We report 2 patients who presented negative for HBsAg but positive for HBeAg and HBV DNA. HBV markers were quantified in the longitudinal sera in a period of 1-2years. The HBV DNA sequences were analyzed in 2 patients' sera and 1 patient's liver.

RESULTS: Both patients were also positive for total anti-HBs and anti-HBc but negative for anti-HBe and anti-HBc IgM. HBV DNA levels were 234-567IU/ml in case 1 and 42-1130IU/ml in case 2. The alignment analysis of the S gene showed that HBV in both patients was genotype C, serotype adr. Cloning analysis of the a determinant of HBsAg showed that the immune escape mutants were predominant in both patients over the follow-up period. The HBV had double mutations (A1762T and G1764A) in the basal core promoter but had no mutation in the pre C/C gene in both patients.

CONCLUSIONS: The patients with negative HBsAg but positive HBeAg may represent a unique type of OBI. Test for HBeAg would be critical to identifying such type of OBI.