STUDY SUBJECT: We longitudinally evaluated the virological behaviour and the hepatitis B virus (HBV) genomic variability in inactive HBV surface antigen (HBsAg) chronic carriers.
Patients and methods: Fourteen HBsAg-positive healthy workers (13 inactive carriers and 1 with active HBV infection) were followed up for 12 months by monthly evaluation of aminotransferase, HBV DNA, and IgM anti HBV core antigen (IgM anti-HBc) values. Moreover, HBV serum isolates from each case were amplified, cloned and sequenced to evaluate the presence of the potentially clinical relevant core-promoter and precore mutations. The same technical procedures were used to examine the S gene of isolates from 3 randomly selected inactive carriers and the patients with active HBV infections.
Results: Aminotransferase values were constantly normal in all cases. Viremia levels appear to fluctuate widely over time in each individual case, although the HBV DNA remained below 2 x 10(4) copies/ml in all samples. Only four serum samples from two inactive carriers had IgM anti-HBc values higher than the specific cut-off limit of the assay. Either wild type or core-promoter/precore HBV variants or a mixture of them were detected in the inactive carriers. S gene nucleotide homology among the clones from the three inactive carriers and the subject with active infection was 98.9%, 98.3%, 98.1% and 98.2%, respectively.
Conclusions: The degree of suppression of HBV replication in inactive carriers is variable over time, and the entity and quality of HBV variability is comparable between active and inactive carriers.