Hepatitis B virus DNA in blood samples positive for antibodies to core antigen and negative for surface antigen

Anti-hepatitis B core antigen (HBcAg)-positive hepatitis B surface antigen (HBsAg)-negative plasma samples from blood donors were tested by nested PCR . DNA positivity was more significantly associated with high levels of anti -HBcAg than with low levels of anti-HBsAg antibodies. Analysis of a dilutio n of anti-HBcAg antibodies might result in a more rational exclusion of ant i-HBcAg-positive HBsAg-negative samples, reducing the number of donations d iscarded and enabling more countries to incorporate anti-HBcAg testing.