Limitations and improvements of the quantiplex branched-DNA assay in Hepatitis B virus-infected patients receiving lamivudine

The branched DNA (bDNA) assay for hepatitis B virus (Chiron Corporation Eme rville, USA) was investigated by application to HBV-infected patients in Ta iwan, where the B and C genotypes of hepatitis B virus are most prevalent. The study group included sera with hepatitis B surface antigen (HBsAg) and e antigen (HBeAg); Group 1 (n = 70) without treatment; Group 2 (n = 28) lam ivudine treatment less than 3 months; Group 3 (n = 73) lamivudine treatment 3-12 months; Group 4 (n = 45) HBeAg-negative sera after I year treatment w ith lamivudine; control group (n = 36) HBsAg-negative sera. Comparison of i dentical-sample results showed a significantly higher coefficient of variat ion for low-level HBV DNA ( < 100 MEq/rnl) than for high-level (greater tha n or equal to 100 MEq/ml), indicating increasing assay inaccuracy uncertain ty as the sample HBV DNA concentration decreased. It is thus concluded that low-titered sera should receive special careful pipetting and processing. It was also found that using the relative luminescence of the negative cont rol plus two standard deviations (S.D.) as a new cutoff could promote sensi tivity (97.1 --> 97.1%, 89.3 --> 100%, 76.7 --> 84.9%, and 17.8 --> 22.2% i n Groups 1-4, respectively) and specificity (94.4 --> 97.2%). In summary, t he bDNA HBV assay showed only moderate assay performance for samples with l ow HBV DNA levels. This problem can be improved partially by choosing a new cutoff value based on the relative luminescence of the negative controls i n the kit. (C) 2001 Elsevier Science B.V. All rights reserved.