One-step real-time PCR assay for detection and quantitation of hepatitis D virus RNA

Hepatitis D virus (HDV) is a defective virus which requires hepatitis B virus (HBV) surface antigen (HBsAg) for its assembly. Hepatitis B infected individuals co-infected or superinfected with HDV often present with more severe hepatitis, progress faster to liver disease, and have a higher mortality rate than individuals infected with HBV alone. Currently, there are no commercially available clinical tests for the detection and quantitation of HDV RNA in the United States. A one-step TaqMan quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for detection of HDV RNA, designing primers located in the region just downstream from the HDV antigen gene. The assay has the potential to detect all eight HDV genotypes. A quantifiable synthetic RNA control was also developed for use in the determination of HDV RNA titers in clinical samples. The limit of detection of this assay is 7.5 × 102 HDV RNA copies/ml with a dynamic range of six logs. Most clinical specimens tested (40/41) fell within the linear range of the assay. The median HDV RNA titer of the tested specimens was 6.24 × 106 copies/ml, with a range of 8.52 × 103-1.79 × 109 copies/ml. Out of 132 anti-HDV-positive specimens 41 (31.1%) were positive for HDV RNA.