Detection of hepatitis B viral DNA by polymerase chain reaction in patients with hepatitis B surface antigen. 
Hepatitis B virus (HBV) DNA was assayed using the polymerase chain reaction in serum samples of 116 hepatitis B surface antigen (HBsAg) carriers, including 30 positive for hepatitis B e antigen (HBeAg) and 86 negative for HBeAg.  In the HBeAg-positive group, all were positive for HBV DNA.  In the HBeAg-negative group, 80.2% were positive for HBV DNA (80.0% in the healthy carrier group, 90.0% in the chronic active liver disease group, and 69.2% in patients with cirrhosis).  This study indicated that every HBeAg-positive carrier as well as the majority of HBeAg-negative carriers were infectious and, in the latter group, that viral replication is most active in patients with chronic active liver disease.