Characterization of a Novel Virus Causing a Lethal Disease in Carp and Koi

Koi herpesvirus (KHV) causes a highly infectious disease afflicting common carp and koi, Cyprinus carpio L. Various molecular and antibody-based detection methods have been used to elucidate the rapid attachment and dissemination of the virus throughout carp tissues, facilitating ongoing development of effective diagnostic approaches. In situ hybridization (ISH) was used here to determine the target tissues of KHV during very early infection, after infecting carp with a highly virulent KHV isolate. Analysis of paraffin-embedded tissues (i.e. gills, skin, spleen, kidney, gut, liver and brain) during the first 8 h and following 10 days post-infection (hpi; dpi) revealed positive signals in skin mucus, gills and gut sections after only 1 hpi. Respiratory epithelial cells were positive as early as 2 hpi. Viral DNA was also detected within blood vessels of various tissues early in the infection. Notable increases in signal abundance were observed in the gills and kidney between 5 and 10 dpi, and viral DNA was detected in all tissues except brain. This study suggests that the gills and gut play an important role in the early pathogenesis of this Alloherpesvirus, in addition to skin, and demonstrates ISH as a useful diagnostic tool for confirmation of acutely infected carp.

Section: Discussionsupporting

confidence: 65%

Examination of the early infection stages of koi herpesvirus (KHV) in experimentally infected carp, Cyprinus carpio L. using in situ hybridization

Monaghan

Thompson

Adams

et al. 2014

“…Since then, it has spread to at least 30 different countries (Haenen & Olesen ) and is now the cause of considerable mortality in the third most farmed freshwater fish in the world, the common carp ( Cyprinus carpio ; FAO ), and in its ornamental variety, koi carp. Losses tend to occur when water temperatures range from 17 to 28 °C (Ilouze, Dishon & Kotler ), and a great deal of effort has been expended on developing methods to control the disease, for example the use of vaccines and ‘natural’ vaccination (Ronen et al . ; Perelberg et al .…”

Section: Introductionmentioning

confidence: 99%

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non‐target species

McColl

Sunarto

Slater

et al. 2016

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV-3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV-3 of a range of non-target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100-1000 times the approximate minimum amount of CyHV-3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post-challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV-3, and, in particular, all RT-PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV-3 as a potential biocontrol agent that is specific for carp.

“…CyHV‐3 was found to spread rapidly and was soon found in almost every country around the world, including Thailand (Chansue & Tangtrongpiros, ). Scientists postulated that the virus enters fish via the gills (Dishon et al., ; Gilad et al., ; Ilouze, Dishon, & Kotler, ; Miyazaki, Kuzuya, Yasumoto, Yasuda, & Kobayashi, ; Pikarsky et al., ), skin (Costes et al., ; Raj et al., ) and periodontal pharyngeal mucosa, where it also resides (Fournier et al., ). CyHV‐3 DNA could be detected via fish excretions (Dishon et al., ) in habitat water, pond sediments and plankton from locations where the disease was reported to have spread (Honjo, Minamoto, & Kawabata, ; Honjo et al., ; Minamoto et al., ).…”

Section: Introductionmentioning

confidence: 99%

Antiviral activities of Clinacanthus nutans (Burm.f.) Lindau extract against Cyprinid herpesvirus 3 in koi (Cyprinus carpio koi)

Haetrakul

Dunbar

Chansue

2018

Cyprinid herpesvirus 3 (CyHV-3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well-known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract against human herpes simplex virus have been reported. In this study, C. nutans crude extract was tested for antiviral activities against CyHV-3 in koi carp. Results showed effective antiviral activity against CyHV-3 pre- and post-infection. The 50% lethal concentration (LC ) of extract was higher than 5 mg/ml. The 50% effective dose (ED ) was 0.99 mg/ml, 0.78 mg/ml, 0.75 mg/ml and 0.71 mg/ml at 1, 2, 3 and 4 hr pre-infection, respectively. The ED from post-infection tests was 2.05 mg/ml and 2.34 mg/ml at 0 and 24 hr, respectively. These results demonstrated that crude extract expressed antiviral activity against CyHV-3 and can be applied as a therapeutic agent in common carp and koi aquaculture.