A survey of salmon gill poxvirus (SGPV) in wild salmonids in Norway

Abstract

In 2016, the Norwegian health monitoring programme for wild salmonids conducted a real-time PCR-based screening for salmon gill poxvirus (SGPV) in anadromous Arctic char (Salvelinus alpinus L.), anadromous and non-anadromous Atlantic salmon (Salmo salar L.) and trout (Salmo trutta L.). SGPV was widely distributed in wild Atlantic salmon returning from marine migration. In addition, characteristic gill lesions, including apoptosis, were detected in this species. A low amount of SGPV DNA, as indicated by high Ct-values, was detected in anadromous trout, but only in fish cohabiting with SGPV-positive salmon. SGPV was not detected in trout and salmon from non-anadromous water courses, and thus seems to be primarily linked to the marine environment. This could indicate that trout are not a natural host for the virus. SGPV was not detected in Arctic char but, due to a low sample size, these results are inconclusive. The use of freshwater from anadromous water sources may constitute a risk of introducing SGPV to aquaculture facilities. Moreover, SGPV-infected Atlantic salmon farms will hold considerable potential for virus propagation and spillback to wild populations. This interaction should therefore be further investigated.

A molecular assessment of infectious agents carried by Atlantic salmon at sea and in three eastern Canadian rivers, including aquaculture escapees and North American and European origin wild stocks

“…Greater than half of escapees carried PRV-1 and ASCV, often as coinfections; for example, most fish positive for ASCV were also positive for PRV-1, and both SGPV-positive hosts were also positive for PRV-1 and ASCV. SGPV has previously been described in Norway and the Northeast Atlantic Ocean (Nylund et al 2008;Garseth et al 2018). In this study, we detected SGPV solely in escaped aquaculture fish, and its occurrence in eastern Canada has been reported to the ICES (ICES 2018).…”

“…Many wild Atlantic salmon stocks come into contact with aquaculture facilities during seaward or spawning migrations, which may result in infectious agent exchange between farmed and wild fish (Heggberget et al 1993;Garseth et al 2018). There is also a persistent issue of escapees from salmon farms mixing with wild stocks, posing further opportunities for pathogen transmission in addition to potential interbreeding and fitness consequences for wild salmon (Castellani et al 2018).…”

Salmon gill poxvirus disease in Atlantic salmon fry as recognized by improved immunohistochemistry also demonstrates infected cells in non‐respiratory epithelial cells

“…The SGPVD problems appeared very widespread as the cases represented both seawater farms and freshwater farms with both recirculation aquaculture systems (RAS) and flow‐through systems (Gjessing, Thoen, Tengs, Skotheim, & Dale, ). In addition, SGPV was reported as prevalent in gills with lesions characteristic for SGPVD in wild salmon broodfish (Garseth, Gjessing, Moldal, & Gjevre, ). Here, we report a study of SGPVD in the early life stages of salmon.…”

“…was reported as prevalent in gills with lesions characteristic for SGPVD in wild salmon broodfish (Garseth, Gjessing, Moldal, & Gjevre, 2018).…”

Isolation and identification of a novel salmon gill poxvirus variant from Atlantic salmon in Eastern Canada

“…It was subsequently found later that year in gills of Atlantic salmon at two marine sites (Nylund et al, 2008). A recent survey in wild and farmed Atlantic salmon in Norway has revealed the ubiquity of the virus, with high viral loads reported in clinically diseased fish (Garseth, Gjessing, Moldal, & Gjevre, 2018;Gjessing, Thoen, Tengs, Skotheim, & Dale, 2017). The complete genome of the virus was sequenced from Atlantic salmon gill tissue collected from Norwegian salmon farms with suspected SGPV-related diseases (Gjessing et al, 2015).…”