Experimental Transmission of Infectious Pancreatic Necrosis Virus from the Blue Mussel, Mytilus edulis, to Cohabitating Atlantic Salmon (Salmo salar) Smolts

Abstract

Integrated multitrophic aquaculture (IMTA) reduces the environmental impacts of commercial aquaculture systems by combining the cultivation of fed species with extractive species. Shellfish play a critical role in IMTA systems by filter-feeding particulate-bound organic nutrients. As bioaccumulating organisms, shellfish may also increase disease risk on farms by serving as reservoirs for important finfish pathogens such as infectious pancreatic necrosis virus (IPNV). The ability of the blue mussel (Mytilus edulis) to bioaccumulate and transmit IPNV to naive Atlantic salmon (Salmo salar) smolts was investigated. To determine the ability of mussels to filter and accumulate viable IPNV, mussels were held in water containing log 4.6 50% tissue culture infective dose(s) (TCID 50 ) of the West Buxton strain of IPNV ml ؊1 . Viable IPNV was detected in the digestive glands (DGs) of IPNV-exposed mussels as early as 2 h postexposure. The viral load in mussel DG tissue significantly increased with time and reached log 5.35 ؎ 0.25 TCID 50 g of DG tissue؊1 after 120 h of exposure. IPNV titers never reached levels that were significantly greater than that in the water. Viable IPNV was detected in mussel feces out to 7 days postdepuration, and the virus persisted in DG tissues for at least 18 days of depuration. To determine whether IPNV can be transmitted from mussels to Atlantic salmon, IPNV-exposed mussels were cohabitated with naive Atlantic salmon smolts. Transmission of IPNV did occur from mussels to smolts at a low frequency. The results demonstrate that a nonenveloped virus, such as IPNV, can accumulate in mussels and be transferred to naive fish.

Spatial and seasonal variability of human and fish viruses in mussels inside and offshore of Ravenna’s harbour (Adriatic Sea, Italy)

“…Furthermore, experimental trials demonstrated that some bivalve mollusk species are able to accumulate and release viable viruses, including NNV (Molloy et al . 2013; Volpe et al . 2017; Kim et al .…”

Infectious Pancreatic Necrosis of Salmonid Fish - Distribution and Laboratory Methods for Diagnosis

“…The disease affected predominantly young salmonidsthe fried trout and Atlantic postsmolts (99). Clinical signs vary and include behavioral changes as spiral swimming, exophthalmos, open operculums bilaterally, anorexia (36).…”

“…After an experimental infection, Molloy et al, demonstrated (2013) that Mytilus edulis has the ability to accumulate and transmit IPNV (99). Other researchers (102) observed viable virus in the digestive gland, muscle, gonads and rectum tissue at 333 day after the experimental injection of IPNV into the adductor muscle of scallop.…”

Discovery of nonnucleoside inhibitors of polymerase from infectious pancreatic necrosis virus (IPNV)

“… 11 Interestingly, while currently unlisted in the Model Aquatic Health Code of the World Organization for Animal Health, the presence of IPNV is continuously being detected worldwide in both aquacultured 12 – 17 and wild fish, including several nonsalmonid species. 15 , 17 – 19 Apart from the fact that this virus is transmitted both vertically and horizontally, 20 , 21 fish that recover or are asymptomatically infected often become carriers of the virus throughout their lives, 11 , 22 contributing to its broad spread. Unfortunately, there is no therapy for this disease, so current protective measures are aimed at avoiding and alleviating its incidence.…”