Hepatitis B virus infection: the impact of molecular biology.

Assays for the detection of nucleic acid in serum are likely to be better systems for determining infectivity than indirect ones dependent on detection of virus-encoded proteins such as HBeAg. The hybridization assays are particularly useful in monitoring spontaneous or treatment-related conversion from the "replicative" to "nonreplicative" phase of HBV infection. The simplified technology described in the papers reported in this issue of Hepatology (9, 14) and their future adaptation to nonisotopic systems will rapidly bring these techniques into everyday clinical practice.