| Summary: | With the increasing problem of sea lice (Lepeoptheirus salmonis) in production of Atlantic salmon (Salmo salar), the use of biological and non-drug treatments, such as cleaner fish, like ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus), have become methods of choice in Norwegian aquaculture. Recently, there has been outbreaks of amoebic gill disease (AGD) caused by the amoeba Neoparamoeba perurans in facilities producing ballan wrasse. This raised several issues, including that AGD-affected ballan wrasse may act as a vector for the amoebae and transfer it to salmon when they are put into salmon farms for delousing. As ballan wrasse is a new species in aquaculture, it has only recently been found to be susceptible to AGD and that it can transfer the amoebae to salmon. Although there has been a lot of studies on AGD in Atlantic salmon and other salmonids, there is little to nothing known about AGD in ballan wrasse. This study was part of a six-week in vivo challenge testing infectivity of UV-irradiated amoebae on ballan wrasse, where for this study, only samples from negative and positive controls were used to look at the cellular and inflammatory response to AGD, and a characterization of the lesions. There was found a significant difference in number of eosinophilic granular cells (EGCs), and apoptotic cells in AGD-associated lesions on filaments in AGD-affected wrasse compared to healthy filaments in AGD-affected fish and non-infected fish. For mucous cells, a significant difference between stains (in AB-PAS) was observed, but no significant difference between the groups. These findings suggest that ballan wrasse, though susceptible to AGD, seems to have a quicker response with more infiltration of EGC and other inflammatory cells, which might correlate with the slower development of the disease than in salmon. Lakselus (Lepeoptheirus salmonis) er det største og stadig økende problemet i norsk akvakultur, og grunnet utvikling av resistens har flere aktører begynt å bruke mer og mer biologiske ...
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