Analytical and clinical validation of 3′ RACE RT-qPCR assay for detection and quantification of hepatitis B virus (HBV) serum RNA

Abstract

BackgroundOver 296 million people worldwide are living with chronic Hepatitis B (CHB) infection who require monitoring of viral activity and disease progression. Serum HBV RNA is a promising new biomarker in CHB management. No standardized method for serum HBV RNA quantification has been established. ObjectivesTo develop and validate, both analytically and clinically, a 3′ RACE RT-qPCR assay for quantification of serum HBV RNA. Study designThe 3′ RACE RT-qPCR method was developed using published primers. The analytical limit of detection and quantification, linearity, inter- and intra-assay repeatability, and clinical specificity and sensitivity were evaluated using synthetic pre-genomic RNA and specimens from various patient populations. Intra- and inter-laboratory ring trials involving three laboratories were completed. ResultsThe 3′ RACE RT-qPCR assay dynamic range is 25 to 108 copies/µL of synthetic RNA. Theoretical and measured serum HBV RNA quantities from a serially diluted sample showed excellent linearity (R2=0.9795). The inter- and intra-assay repeatability were 94.91% and 95.12%, respectively. Clinical specificity and sensitivity were 100% and 90%, respectively, in treated patients. Inter-laboratory analysis demonstrated moderate to high agreement among participating laboratories (κ = 0.581 to 0.867). High agreement was also observed between both operators participating in the intra-laboratory evaluation (κ = 0.867). ConclusionsOur methodology for the quantification of serum HBV RNA is specific and repeatable and employs a biologically relevant RNA standard suitable for medium throughput laboratories. Method standardization is required to facilitate the comparison of studies and better understand the clinical role of this novel biomarker.