Development of an RT-qPCR Assay for the Detection of an Emerging Duck Egg-Reducing Syndrome.

Duck egg-reducing syndrome virus (DERSV) is a novel Avihepatovirus and is responsible for a gradual decline in the laying rate of ducks, decreasing from a peak of 90% to 50%. The development of a rapid detection method for DERSV is crucial for the identification and control of virus infections. In this study, we developed a quantitative reverse transcription PCR (RT-qPCR) assay for detecting DERSV. Specific primers and a probe were designed to target a conserved region of the 3D gene. The assay demonstrated high specificity, with no cross-reactivity to other non-target duck viruses. It had a detection limit of 10 copies and a linear range from 10 to 10 copies per reaction. The assay's efficiency was 92.59%, with a regression coefficient (R) of 0.999. The coefficient of variation for both intra-and inter-assays was less than 2.00%. Among the 153 clinical samples collected from 2016 to 2023, the RT-qPCR detected a DERSV positive ratio of 47.06% (72/153). In conclusion, the utilization of the real-time RT-qPCR assay holds potential for the detection of DERSV in epidemiological and pathogenesis studies.