Mass Mortality Associated With Koi Herpesvirus in Wild Common Carp in Canada

Garver, Kyle A.; Al-Hussinee, Lowia; Hawley, Laura M.; Schroeder, Tamara; Edes, Sandra; LePage, Véronique; Contador, Elena; Russell, Spencer; Lord, Stephen; Stevenson, R. M. W.; Souter, B. W.; Wright, Elizabeth; Lumsden, John S.

doi:10.7589/0090-3558-46.4.1242

Cited by 56 publications

(40 citation statements)

References 13 publications

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“…These laboratories could detect CyHV-3 in experimentally exposed koi displaying clinical signs of infection within 3 d following virus challenge with isolate U-NY1999. The virus load (10 6.81 ± 10 7.07 equivalent plasmid copies per µg DNA) and the wide range of virus quantities (range 10 1.95 to 10 7.87 equivalent plasmid copies per µg DNA) found in the experimentally infected koi were similar to values reported for CyHV-3 in wild carp undergoing an outbreak of KHVD (Garver et al 2010). In the absence of available samples from a natural KHVD outbreak, tissues from the experimentally infected koi served as suitable proxies for a natural acute infection.…”

Section: Discussionsupporting

confidence: 75%

Diagnostic validation of three test methods for detection of cyprinid herpesvirus 3 (CyHV-3)

Clouthier

McClure²,

Schroeder³

et al. 2017

Dis. Aquat. Org.

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Cyprinid herpesvirus 3 (CyHV-3) is the aetiological agent of koi herpesvirus disease in koi and common carp. The disease is notifiable to the World Organisation for Animal Health. Three tests -quantitative polymerase chain reaction (qPCR), conventional PCR (cPCR) and virus isolation by cell culture (VI) -were validated to assess their fitness as diagnostic tools for detection of CyHV-3. Test performance metrics of diagnostic accuracy were sensitivity (DSe) and specificity (DSp). Repeatability and reproducibility were measured to assess diagnostic precision. Estimates of test accuracy, in the absence of a gold standard reference test, were generated using latent class models. Test samples originated from wild common carp naturally exposed to CyHV-3 or domesticated koi either virus free or experimentally infected with the virus. Three laboratories in Canada participated in the precision study. Moderate to high repeatability (81 to 99%) and reproducibility (72 to 97%) were observed for the qPCR and cPCR tests. The lack of agreement observed between some of the PCR test pair results was attributed to cross-contamination of samples with CyHV-3 nucleic acid. Accuracy estimates for the PCR tests were 99% for DSe and 93% for DSp. Poor precision was observed for the VI test (4 to 95%). Accuracy estimates for VI/qPCR were 90% for DSe and 88% for DSp. Collectively, the results show that the CyHV-3 qPCR test is a suitable tool for surveillance, presumptive diagnosis and certification of individuals or populations as CyHV-3 free.KEY WORDS: CyHV-3 · Diagnostic validation · Precision · Accuracy · Quantitative PCR · Virus isolation Resale or republication not permitted without written consent of the publisherDis Aquat Org 123: 2017 ment on the Application of Sanitary and Phytosanitary Measures.An effective CyHV-3 diagnostic assay should detect the virus in diseased fish as well as in asymptomatic carriers of the virus with latent or persistent infections. Three diagnostic assays were evaluated for their performance characteristics in this study: a modified conventional polymerase chain reaction (cPCR) assay targeting the CyHV-3 thymidine kinase gene (cTK;Bercovier et al. 2005), a modified quantitative PCR (qPCR) assay targeting CyHV-3 open reading frame 89 (ORF89) (qORF89; Gilad et al. 2004) and virus isolation by culture on common carp brain (CCB) cells (VI;Neukirch et al. 1999). The unmodified cTK and qORF89 tests have been evaluated in inter-laboratory ring studies (Way 2008) and intralaboratory comparisons (Bergmann et al. 2010, Monaghan et al. 2015a). The qPCR test displayed high analytical specificity (ASp), detecting all known CyHV-3 isolates but not related virus species such as CyHV-1 or CyHV-2 (Gilad et al. 2004, Bergmann et al. 2010. It is currently the most commonly used diag nostic test for CyHV-3 and may prove to be suitable for use in surveillance programs to declare healthy populations of susceptible fish free of the virus (OIE 2015c). The cTK test is one of the PCR assays recommended by the OIE fo...

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Section: Discussionsupporting

confidence: 75%

Diagnostic validation of three test methods for detection of cyprinid herpesvirus 3 (CyHV-3)

Clouthier

McClure²,

Schroeder³

et al. 2017

Dis. Aquat. Org.

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“…Cyprinid herpesvirus-2 is the etiological agent of herpesviral hematopoietic necrosis disease (HVHN) and is found in closely related species, including goldfish Carassius auratus (Jeffery et al 2007, Goodwin et al 2009), Prussian carp Carassius gibelio (Daně k et al 2012, Xu et al 2013, and crucian carp Carassius carassius (Fichi et al 2013). The CyHVs cause serious mortality in fish; carp pox pro-duces a papillomatous disease in carp fry (Sano et al 1991), and koi herpesvirus can result in massive fish kills in the wild (Hedrick et al 2000, Garver et al 2010. Cyprinid herpesvirus-2 (CyHV-2) has a wide geographic distribution, and in North America it has been mainly associated with mortality in goldfish farms (Goodwin et al 2006a).…”

Section: Introductionmentioning

confidence: 99%

Cyprinid herpesvirus-2 causing mass mortality in goldfish: applying electron microscopy to histological samples for diagnostic virology

Lovy¹,

Friend²

2014

Dis. Aquat. Org.

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In June 2013, a major fish kill of adult goldfish Carassius auratus occurred in Runnemede Lake, New Jersey, USA: an estimated 3000 to 5000 fish died within ~5 d. Necropsy of 4 moribund fish revealed severely pale gills, and histopathology showed type I and II fusion of the gills, diffuse necrosis of hematopoietic tissue in anterior and posterior kidney, and multifocal necrosis of the spleen. Within necrotic areas, pyknosis and enlarged nuclei with marginalized chromatin were observed. Cyprinid herpesvirus-2, the etiological agent for herpesviral hematopoietic necrosis disease, was confirmed in all 4 fish using PCR. We assessed the efficacy of identifying herpesviral infections (viral morphogenesis and cellular ultrastructure) using transmission electron microscopy (TEM) when applied to tissues fixed in 10% neutral buffered formalin (NBF) and tissue that was removed from paraffin blocks. Both sample types could be used to detect the virus within cells at similar concentrations. Tissues reprocessed from 10% NBF contained all the known stages of viral morphogenesis including empty capsids, capsids with an inner linear concentric density, capsids with an electron-dense core, and in the cytoplasm, mature capsids containing an envelope. Paraffin-embedded tissues showed similar stages, but viral capsids with an inner linear concentric density were rare and mature enveloped virions were not observed. In previously paraffin-embedded tissues, cellular membranes were not preserved, making identification of cell types and organelles difficult, whereas membrane preservation was good in tissues processed from 10% NBF. The results demonstrated that routinely fixed and paraffin-embedded samples can be successfully utilized to diagnose herpesviruses, and formalin-fixed tissue could be used to describe viral morphogenesis by TEM, making this a useful and reliable method for diagnostic virology when other samples are not available.

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“…Studies around the world show a mortality rate of 80 to 100% in creations of carps infected by both CyHV-2 and CyHV-3 [16,17,18,19,20] as well by IcHV-1 that infects channel catfish [21], the 3 types of fish herpesvirus most frequent. Not yet know here in Brazil, which are the types of herpes viruses that are present in fish.…”

Section: Discussionmentioning

confidence: 99%