COMPARISON OF 4 METHODS FOR QUANTITATIVE MEASUREMENT OF HEPATITIS-B VIRAL-DNA

Aims/Methods: Four assays for measuring HBV-DNA quantitatively have be en compared with regard to sensitivity, precision and linearity. The m ethods were I-125-labelled solution hybridisation assay (liquid hybrid isation, Abbott), an ELISA-based chemiIuminescent RNA-DNA hybrid assay (RNA-DNA, Digene), a chemilumimescent branching oligonucleotide assay (bDNA, Chiron) and a membrane hybridisation assay using slot-blot equ ipment (slot blot). Results: The bDNA assay was linear over three orde rs of magnitude and was the most sensitive assay, being approximately ten times more sensitive than the other assays, so that samples negati ve on RNA-DNA, liquid hybridisation and slot blot gave quantifiable re sults on bDNA, Furthermore, intra- and inter-assay variability showed that the bDNA and liquid hybridisation assays had the greatest precisi on, with coefficients of variation of 6.6% to 11.5% and 2.3% to 10.5%, respectively. However, the nominated amounts of HBV DNA in the standa rds (from all assays) were plot reproducible in the other assays, such that amounts measured with bDNA would give values approximately twice that of RNA-DNA and 60 times that of liquid hybridisation. Conclusion s: The recently developed bDNA assay has advantages compared with the other assays in quantitating samples with low levels of virus present, In addition, since the assays vary considerably by a number of criter ia, the method of measurement should always be reported.