Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2023
Höfundar / Authors: Sigurdardottir HS, Casás Casal S., Bjornsdottir TS, Kristmundsson A
Starfsvettvangur / Affiliations: Keldur Institute for Experimental Pathology, University of Iceland, Reykjavik, Iceland
Kynnir / Presenter: Heiða Sigurðardóttir
Infectious salmon anemia (ISA) is a serious viral disease of Atlantic salmon (Salmo salar L.) caused by the ISA virus (ISAV) and is notifiable to the World Organization for Animal Health (OIE). Virulent strains ISAV-HPRdel have deletions in a highly polymorphic region (HPR) of the hemagglutinin-esterase (HE) gene on segment 6, whereas avirulent strains ISAV-HPR0 have none.
ISAV screening with RT-qPCR started at Keldur in 2011. The few samples that have been ISAV positive from broodfish are HPR0 genotypes. A research project carried out at Keldur from 2015-2018 screened both wild and cultured salmon juveniles, cultured salmon in sea pens and wild salmon from rivers (a total of about 800 fish) for ISAV, which was not detected.
In November 2021, increased mortality was experienced in farmed Atlantic salmon in sea pens in Reyðarfjörður, East Iceland. The fish showed macroscopic clinical signs suggestive of ISAV. Tissue samples and organs were sent to Keldur for diagnosis, using ISAV RT-PCR and histopathological analysis. The histopathology of the diseased fish was consistent with previous descriptions of ISAV infections in Atlantic salmon.
RT-qPCR results for ISAV were positive with Ct. values ranging from 14-27. Sequencing of ISAVseg6 PCR amplicons showed that they were HPRdel variants. Confirming the first detection of an ISAV-HPRdel variant in Iceland.