Akademik Veri Yönetim Sistemi
Fish and Shellfish Immunology Reports, cilt.2, ss.1-14, 2021 (Hakemli Dergi)
Gill diseases may cause high mortalities in farmed Atlantic salmon. In seawater reared fish co-infections
involving the epitheliocystis associated bacterium Ca. Branchiomonas cysticola, the microsporidian Desmozoon
lepeophtherii, the causative agent of amoebic gill disease Paramoeba perurans and salmon gill poxvirus are
common and histopathological lesions may be complex. Here, we report detection of these agents utilising
multiplex real-time PCR and link the presence of agents to histopathologically visible gill lesions by in situ
hybridisation (ISH) utilising RNAscope®. We show that Ca. Branchiomonas cysticola infections may remain
undetected if diagnostic investigations are restricted to histopathology alone. Further, positive in situ labelling of
Ca. Branchiomonas cysticola was observed within epitheliocysts, but also in small foci within areas of inflammation
and necrosis in which histologically detectable epitheliocysts were not visible. In situ labelling of
D. lepeophtherii corresponded well with tissue distribution patterns previously associated with this microsporidian.
Salmon gill poxvirus was associated with apoptotic gill epithelial cells, while Ca. Piscichlamydia
salmonis could not be associated with pathological changes. The multiplex real-time PCRs utilised were rapid
and sensitive diagnostic tools and the results corresponded well with ISH. This study shows that the agents
involved in complex gill disease can be linked to lesions using ISH and suggests that Ca. B. cysticola plays a
crucial role in the development of gill disease in the farming of salmon in Norway.