Detection of nodavirus in seawater from rearing facilities for Atlantic halibut Hippoglossus hippoglossus larvae

Abstract

We used (1) ultracentrifugation followed by RT-PCR and (2) real-time RT-PCR to detect and quantify nodaviruses in seawater in which Atlantic halibut Hippoglossus hippoglossus larvae/fry had been held at rearing facilities. Evaluated against in vitro propagated viruses, the viral concentration corresponded to 1.6 × 10 4 TCID 50 (50% tissue culture infectious dose) ml-1. Evaluated against in vitro transcribed RNA, the concentration was estimated at 2 × 10 7 virus particles ml-1 seawater.

Real-Time Quantitative PCR Assay for Monitoring of Nervous Necrosis Virus Infection in Grouper Aquaculture

“…The presently developed method was capable of detecting from 1.0 ϫ 10 9 copies to as low as two copies per reaction. Detection of two virus copies per reaction can easily identify fish recently infected with NNV that have been hitherto clinically silent and represents the most sensitive detection method described to date (5,8,10,18,19). Moreover, a linear regression of over 0.99 (r 2 Ͼ 0.99) produces a CV from 0.9% to 6.34% for the plasmid assay and 0.34% to 5.07% for the viral assay, indicating that the assays are highly reproducible.…”

Nodavirus in farmed Atlantic cod Gadus morhua in Norway

“…RNA from tissue samples was extracted using Trizol (Invitrogen) and an RNAeasy kit (Qiagen) according to the manufacturer's instructions and stored at -80°C. Tissues sampled were analysed by 2 assays, both using nodavirus-specific primers and probes (Korsnes et al 2005, Nerland et al 2007). Heart tissues were also screened for the presence of infectious pancreatic necrosis virus (IPNV) as described by Watanabe et al (2006) and kidney tissue for Francisella sp.…”

Betanodavirus of Marine and Freshwater Fish: Distribution, Genomic Organization, Diagnosis and Control Measures

“…Feeding of trash fish to cultured fish is also found to be a source of infection [47]. Some of the betanodavirus infected larval fish can survive and act as a carrier for the next generation [87]. Several authors studied the horizontal transmission of this virus during outbreaks and confirmed it by various experimental studies [3,15,88].…”

“…Realtime PCR also is sometimes used for rapid and sensitive detection of this virus. As nodavirus is very stable and can survive in seawater for a long time [36], it has been possible to detect and quantify the virus in seawater from rearing facilities for Atlantic halibut H. hippoglossus larvae [87]. Real-time PCR assay has been useful to study the transmission and development of this viral infection in juvenile [56].…”

“…It can persist in the host for a long time sub-clinically and may cause severe mortality under extreme environmental conditions [105]. The horizontal transmission may occur from infected fish, feed, contaminated trash fish/carrier animals and contaminated water supply [18,44,47,69,87,119]. The cannibalistic nature of fish such as Asian seabass and brown-marbled grouper fingerlings may also enhance the horizontal transmission of the virus [78].…”