Hepatitis B virus DNA in relation to duration of hepatitis B surface antigen carriage

This study determined the prevalence and concentration of hepatitis B virus (HBV) DNA in chronic carriers of hepatitis B surface antigen (HBsAg) in The Gambia, West Africa. Ninety-nine young child carriers aged three to four years, 115 older child carriers aged five to 14 years, 71 adult carriers and 105 infected children who were not carriers were included. Detection of HBV DNA was performed by dot blot hybridisation using a radioactive phosphorus (32P) method and by non-radioactive enhanced chemiluminescence (ECL). Chromoscan-3 equipment was used to quantify DNA, and ECL and the 32P method were compared. Sensitivity and specificity of ECL were 95.8% and 100% respectively, with a detection limit of 0.3 pg/microL (0.3 x 10(5) genomic copies) compared to 0.15 pg/microL (0.15 x 10(5) genomic copies) for the 32P-labelled probe. The prevalence of HBV DNA was 74% (74/99) in young carriers, 30% (35/115) in older child carriers and 12.6% (9/71) in adult carriers. The geometric mean (GM) values for HBV DNA were significantly different between age groups (P = 0.031) and HBV DNA, which declined significantly with age (r = 0.16, P < 0.001 for log32P values), ranged from 1.48 pg/microL in young carriers to 0.29 pg/microL in adults over 24 years. The GM value of HBV DNA was related to duration of carriage. Higher values were found in young carriers known to be HBsAg-positive for less than three years compared with adult carriers of at least 20 years' duration. The GM (95% confidence limit [CL]) values were 1.48 pg/microL (1.42, 1.53) and 0.29 pg/microL (0.25, 0.33) respectively. The level of HBV DNA in hepatitis B envelope antigen (HBeAg)-positive carriers was higher than in HBeAg-negative carriers, the GM (95% CL) being 1.23 pg/microL (1.19, 1.27) and 0.34 pg/microL (0.25, 0.42) respectively.