Performance of the cobas® HBV RNA automated investigational assay for the detection and quantification of circulating HBV RNA in chronic HBV patients

•HBV RNA in blood may reflect cccDNA transcriptional activity in infected cells.•Circulating HBV RNA is a promising biomarker for monitoring antiviral treatment.•cobas HBV RNA is sensitive (LLOQ: 10 copies/mL), specific, and genotype inclusive.•cobas HBV RNA has high throughput and may be useful for management of HBV infection. The amount of HBV RNA in peripheral blood may reflect HBV covalently closed circular DNA (cccDNA) transcriptional activity within infected hepatocytes. Quantification of circulating HBV RNA (cirB-RNA) is thus a promising biomarker for monitoring antiviral treatment. We evaluated the performance of an automated, prototype quantitative HBV RNA assay for use on the Roche cobas® 6800/8800 systems. The sensitivity, specificity, linearity, and potential interference by HBV DNA of the cobas® HBV RNA assay were assessed using synthetic HBV armored RNA and clinical specimens. cobas® HBV RNA results were linear between 10 and 107 copies/mL in clinical samples of several HBV genotypes, and up to 109 copies/mL with synthetic RNA. Precision and reproducibility were excellent, with standard deviation below 0.15 log10 copies/mL and coefficients of variation below 5% throughout the linear range. The presence of HBV DNA had minimal (