Persistence of HBV-DNA in children with chronic hepatitis B who seroconverted to anti-HBs antibodies after interferon-α therapy: correlation with specific IgG subclass responses to HBsAg

Background/Aims We examined the persistence of HBV-DNA in sera collected 4–10 years after IFN-α therapy from patients with chronic hepatitis B who had seroconverted to anti-HBs antibodies. We also wanted to assess whether any association exists between HBV-DNA status and the IgG anti-HBs subclass responses. Methods Sera were obtained from 38 patients and the following parameters were determined in each of them: (1) serological markers of HBV; (2) concentrations of IgM, IgG, IgA; (3) total IgG subclasses. HBV-DNA and IgG anti-HBs subclasses were determined in anti-HBs positive sera. Results Four to 10 years after therapy, anti-HBs were found in 37 of 38 patients (GMT: 775 IU/L). In 13 of them (35.1%) free and/or bound HBV-DNA was present in sera. Significant differences in the profiles of IgG anti-HBs were observed when the HBV-DNA status was considered. Patients with undetectable HBV-DNA responded mainly with IgG1 and/or IgG3, while in the HBV-DNA-positive group, a high contribution of IgG4 was found. Conclusions Our study showed that HBV-DNA may persist for a long time after IFN-α therapy despite the appearance of anti-HBs antibodies. The monitoring of specific IgG subclasses may be of predictive value for HBV-DNA persistence.