Successful interferon treatment in a patient chronically infected with hepatitis B virus carrying unusual S- (and P-) mutants in the presence of anti-HBs antibodies.

Background: Hepatitis B virus (HBV) immune escape mutants with point mutations within the S gene may arise during the natural course of HBV infection, due to a positive selection pressure exerted by the host immune response. Mutations within the immunodominant B and T cell epitopes of hepatitis B surface antigen (HBsAg) allow the resulting S-mutants to propagate even in the presence of neutralizing anti-HBs antibodies and the HBV-specific T-cell immune response.

Aim: To study the antiviral effect of Pegylated-interferon (Peg-IFN) in a patient with chronic hepatitis B carrying unusual S-(and P-) mutants in the presence of anti-HBs antibodies.

Patients, Methods And Results: We report on a 43-year-old male chronically infected with a genotype A HBV strain, with cocirculation of both HBsAg and anti-HBs antibodies, who received treatment with 120 mug of Peg-IFN for 24 weeks. HBeAg seroconversion and clearance of both HBV DNA by polymerase chain reaction and HBsAg were successfully achieved. Improved histology was observed in a biopsy performed 44 weeks after Peg-IFN therapy was completed. It seems plausible that the ascribed genotype A could have contributed to the effective response to Peg-IFN, even though the treatment was provided only throughout a 24-week period.

Conclusion: To our knowledge, this is the first report regarding the successful result obtained by using Peg-IFN as a treatment for a chronically HBV-infected patient carrying HBsAg immune escape mutants.