Detection and Differentiation of the Vaccine Strain and Field Isolates of Duck Hepatitis a Virus Type 1 Using Real-Time Rt-PCR and High Resolution Melting Assays

Duck hepatitis A virus type 1 (DHAV-1) infection is a highly contagious and fatal disease of young ducklings. A live attenuated vaccine strain designated as 5886 has been used in Taiwan for the control of DHAV-1. Although several molecular biological methods are reported for diagnosis of DHAV-1 infection, none of them is able to discriminate between the vaccine strain and field viruses of DHAV-1. In the present study, a real-time reverse transcriptase polymerase chain reaction (RT-PCR) and high resolution melting (HRM) assay was developed for rapid detection and differentiation between the vaccine strain and field viruses of DHAV-1. This assay is highly specific for DHAV-1 and the detection limit is about 100 copies of the viral RNA. Experiments using fecal samples collected from ducklings experimentally infected with DHAV-1 showed that DHAV-1 could be detected in fecal samples as early as 6 h post-infection. In summary, a real-time RT-PCR and HRM assay is developed in this study and this assay could be valuable for diagnosis and surveillance of DHAV-1 infection in the field.