Semiautomated quantification of hepatitis B virus DNA in a routine diagnostic laboratory

The Cobas Amplicor HBV Monitor test for quantitative determination of hepat itis B virus (HBV) DNA in serum has recently been introduced. To evaluate t he performance of this assay in a routine diagnostic laboratory, reproducib ility of results was determined with the First European Union Concerted Act ion HBV Proficiency Panel and the Accurun 325 HBV DNA Positive Control, Ser ies 300. Results for 270 routine serum samples were additionally evaluated. To avoid the retesting of a large number of samples due to titers exceedin g the upper limit for the linear range of the assay, sera of patients with chronic hepatitis B (CHB) were diluted prior to the assay to 10(-4) in norm al human plasma, which is included in the assay. The mean coefficient of va riation was 22.9% for all input HBV DNAs. Of 270 routine serum samples, 182 (150 sera from transplant donors and 32 sera from patients who had recover ed from CHB) tested negative. Eighty-six sera were found to be HBV DNA posi tive; in six sera, HBV DNA levels were found to exceed the upper limit for the linear range of the assay and had to be retested. In the remaining two sera, inhibition occurred. The semiautomated Cobas Amplicor HBV Monitor tes t showed sufficient reproducibility and helped in avoiding human error. The relatively narrow linear range of detection is a limitation of the new ass ay.