Fate of infectious salmon anaemia virus (ISAV) in experimentally challenged blue mussels Mytilus edulis

Abstract

In order to investigate the potential role of blue mussels Mytilus edulis as a vector of the fish pathogenic infectious salmon anaemia virus (ISAV), we developed an experimental bioaccumulation system in which mussels can accumulate virus during normal filtration. Detection of virus in mussels was performed by means of real-time RT-PCR. ISAV-RNA was detected in the mussels until 72 h post-challenge. Hepatopancreas homogenate from experimentally challenged mussels was injected into salmon. All the fish injected with homogenate prepared immediately after accumulations were strongly ISAV positive 4 wk post-challenge. In the group injected with homogenate prepared 24 h after the challenge, 1 fish out of 25 was weakly ISAV positive. All of the fish that were challenged with mussel homogenate prepared 96 h after accumulation were ISAV negative. Mussels sampled from a tank with experimentally infected salmon demonstrating clinical signs consistent with ISA (infectious salmon anaemia) and mussels collected on net pen cages during ISA outbreaks in Atlantic salmon were all ISAV negative. The results indicate that the ISAV is rapidly inactivated in mussels and that mussels are not a likely reservoir host or vector for ISAV.

The Development of Sustainable Saltwater-Based Food Production Systems: A Review of Established and Novel Concepts

“…Organic extractive species (e.g., mussels) have also demonstrated their ability to consume parasites and inactivate pathogens. The novel use of cleaner-fish is also being trialed and has shown promise in, for example, the removal of sea-lice from Atlantic salmon [145,146,177,178]. Culturing species form different trophic levels can achieve environmental stability through the biomitigation of aquaculture wastes, while at the same time providing the farmer economic stability through product diversification [2,129].…”

“…If V. anguillarum can persist in mussel fecal pellets, it is possible that mussels could generate Vibrio reservoirs in sediments and/or fecal matter [4,144]. Other studies, however, have demonstrated that bivalves are not hosts, instead consuming parasites or inactivating pathogens [145,146]. More research into bivalves' ability to act as pathogen reservoirs is required, however, steps can be taken to minimize the risk of transmission.…”

“…Due to filter-feeding organisms' (e.g., bivalves) ability to consume or deactivate potential pathogenic microorganisms and parasites, their inclusion in an IMTA system provides the opportunity to decrease disease outbreaks and control human pathogens. Subsequently the need for antibiotics may be significantly reduced [2,4,129,130,145,146]. It must be noted that there is the possibility that bivalves can act as a vector for fish pathogens, however, studies on this are limited [4,144].…”

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

“…Bivalves bioaccumulate both viral and bacterial finfish pathogens (5)(6)(7)(8)(9)(10). The physiology of the pathogen influences whether the pathogen remains viable in shellfish tissues and is shed back into the environment.…”

Fate of Francisella noatunensis, a pathogen of Atlantic cod Gadus morhua, in blue mussels Mytilus edulis

“…For instance, blue mussels may have a beneficial effect in a net pen environment by reducing the amount of the kidney disease bacterium Renibacterium salmoninarum present (Paclibare et al 1994). Bivalves are also capable of retaining fish pathogenic viruses, but persistence periods vary greatly, presumably reflecting differences in the robustness of the viruses (Mortensen et al 1992, Skår & Mortensen 2007.…”