Infectious salmon anemia vlrus (ISAV) was isolated at a marine grow-out site in New Brunswick. Canada, from Atlantic salmon Salmo salar which experienced mortalities due to hemorrhagic kidney syndrome (HKS). Of 20 fish sampled in this study, 14 showed histologically various degrees of interstitial hemorrhaging, tubular epithelia1 degeneration and necrosis, and tubular casts in the posterior kidney, typical of HKS. Posterior kidney and spleen homogenates produced a cytopathic effect on chinook salmon embryo (CHSE-214) cells 10 to 14 d after inoculation. Pleomorphic virus particles in the size range 80 to 120 nm were seen by electron microscopy. The virus was confirmed as ISAV using reverse transcriptase-polymerase chain reaction (RT-PCR) This is a systematic diagnostic study of the isolation of ISAV on the North American continent and the first description of the growth of ISAV on the CHSE-214 cell line.

The role of parasitic sea lice (Siphonostomatoida; Caligidae), especially Lepeophtheirus salmonis, in the epidemiology of Infectious Salmon Anemia Virus (ISAv) has long been suspected. The epidemiological studies conducted during the 1998 major Infectious Salmon Anaemia (ISA) outbreak in Scotland demonstrated a strong correlation between sea lice presence and ISAv positive sites or subsequent clinical outbreaks of ISA. The question posed from this observation was “do sea lice infestations on Atlantic salmon make them more susceptible to viral infections?”This study investigated the role that sea lice infestations have on the severity of ISAv infections and disease mortality in experimental populations of farmed Atlantic salmon (Salmo salar). A series of experiments was carried out that investigated the potential of sea lice to modify the outcome of an ISAv infection. Experimental populations of Atlantic salmon were established that had: no lice and no ISAv, a single infection with either ISAv or lice and a co-infection with lice then ISAV. The results were quite clear, the process of infestation by the parasite prior to ISAv exposure significantly increased the mortality and death rates of Atlantic salmon, when compared to uninfected controls and ISAv infected groups only. This was consistent over two source strains of Atlantic salmon (Pennobscot and Saint John River), but the severity and timing was altered. Immunological responses were also consistent in that pro-inflammatory genes were induced in lice only and co-infected fish, whereas the anti-viral response, Mx, MH class I β, Galectin 9 and TRIM 16, 25 genes were down-regulated by lice infection prior to and shortly after co-infection with ISAv. It is concluded that the sea lice settlement on Atlantic salmon and the parasite’s subsequent manipulation of the host’s immune system, which increases parasite settlement success, also increased susceptibility to ISAv.

Integrated multi-trophic aquaculture (IMTA) is an exciting alternative approach to mono-culture aquaculture that reduces environmental impacts of commercial aquaculture systems by combining the cultivation of fed aquaculture species (finfish) with extractive aquaculture species (e.g., shellfish and seaweed). This increases the sustainability and profitability of finfish culture as the organic particulate wastes can be removed by the shellfish extractive component and dissolved inorganic nutrients are extracted by the seaweed component. Shellfish play a critical role in an IMTA system by extracting particulate bound organic nutrients; however they may also influence pathogen dynamics by serving as a reservoir or as a barrier for finfish pathogens, depending on pathogen physiologies. The sea louse, Lepeophtheirus salmonis, has recently made a spectacular comeback as a major parasitic pest of farmed Atlantic salmon (Salmo salar L.) in the Northeast of the United States. The re-emergence of this parasite is due to development of louse resistance to SLICE™, the drug of choice for treating L. salmonis infestations over the last decade. Incorporation of mussel crops on salmon farms may be an alternative method to reduce the infectious pressure of sea lice on farms if mussels can consume copepodids, the planktonic and infectious stage of sea lice. Our study demonstrated that mussels can remove copepodids from the water column. Individual mussels were exposed to copepodids (200 copepodids l −1) for 30-and 60-min durations. Copepodids were observed in the buccal cavity and in stomach contents. Molecular analyses confirmed the presence of copepodids in mussel stomach contents.

Infectious salmon anemia (ISA) is a severe disease primarily affecting commercially farmed Atlantic salmon (Salmo salar) in seawater. The disease has been reported in portions of Canada, the United Kingdom, the Faroe Islands, and the United States. Infectious salmon anemia virus (ISAV), the causative agent of ISA, has also been isolated from several asymptomatic marine and salmonid fish species. Diagnostic assays for the detection of ISAV include virus isolation in cell culture, a reverse transcriptase-PCR, an enzyme-linked immunosorbent assay, and an indirect fluorescent antibody test. Virus isolation is considered the gold standard, and 5 salmonid cell lines are known to support growth of ISAV. In this study, the relative performance of the salmon head kidney 1 (SHK-1), Atlantic salmon kidney (ASK), and CHSE-214 cell lines in detecting ISAV was evaluated using samples from both experimentally and naturally infected Atlantic salmon. Interlaboratory comparisons were conducted using a quality control-quality assurance ring test. Both the ASK and SHK-1 cell lines performed well in detecting ISAV, although the SHK-1 line was more variable in its sensitivity to infection and somewhat slower in the appearance of cytopathic effect. Relative to the SHK-1 and ASK lines, the CHSE-214 cell line performed poorly. Although the ASK line appeared to represent a good alternative to the more commonly used SHK-1 line, use of a single cell line for diagnostic assays may increase the potential for false-negative results. Thus, the SHK-1 and ASK cell lines can be used in combination to provide enhanced ability to detect ISAV.

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