DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03768

ABSTRACT: White sturgeon (Acipenser transmontanus) is the primary species used for caviar and sturgeon meat production in the USA. An important pathogen of white sturgeon is Acipenserid herpesvirus 2 (AciHV-2). In this study, four archived isolates from temporally discrete natural outbreaks spanning the past 30 years were sequenced via Illumina and Oxford Nanopore Technologies platforms. Assemblies of approximately 134 Kb were obtained for each isolate, and the putative ATPase subunit of the terminase gene was selected as a potential quantitative PCR (qPCR) target based on sequence conservation among AciHV-2 and low sequence homology with other important viral pathogens. The qPCR was repeatable and reproducible, with a linear dynamic range covering 5 orders of magnitude, an efficiency of approximately 96%, an R² of 0.9872 and an analytical sensitivity of 10³ copies per reaction after 35 cycles. There was no cross-reaction with other known viruses or closely related sturgeon species, and no inhibition by sturgeon DNA. Clinical accuracy was assessed from white sturgeon juveniles exposed to AciHV-2 by immersion. Viral culture (gold standard) and qPCR were in complete agreement for both cell culture negative and cell culture positive samples, indicating this assay has 100% relative accuracy compared to cell culture during an active outbreak. The availability of a whole genome sequence for AciHV-2 and a highly specific and sensitive qPCR assay for detection of AciHV-2 in white sturgeon lays a foundation for further studies on host-pathogen interactions while providing a specific and rapid test for AciHV-2 in captive and wild populations.