title: Infectious salmon anaemia virus (ISAV) in experimentally challenged Atlantic cod (Gadus morhua).
abstract: Juvenile Atlantic cod, Gadus morhua, (6 g) were challenged with infectious salmon anaemia virus (ISAV) either by intraperitoneal (i.p.) injection or by cohabitation with ISA-diseased Atlantic salmon (Salmo salar). Samplings of cod were performed over a period of 45 days and various tissue samples were collected. The presence of ISAV RNA (segment 8) in samples was assessed by both conventional RT-PCR and a competitive quantitative real-time RT-PCR. In the i.p.-challenged group, ISAV RNA was detected in fish from all samplings, i.e. at days 7, 15, 21, 30 and 45 post-challenge. At day 7 post-challenge, all individual fish were positive, and so were the vast majority of individual tissue samples. At later samplings, the fraction of positive brain samples remained high (approximately 75%). In contrast, the positive fraction of other tissues/organs declined during the experiment. Analysis of positive brain samples by a quantitative real-time RT-PCR analysis showed that the level of ISAV RNA increased significantly (approximately 20 times) between days 7 and 30 post-challenge and remained high at day 45, indicating that a replication of ISAV had taken place. ISAV RNA was not detected in any control or cohabitation-challenged fish. No abnormal behaviour, clinical disease or, most notably, mortality was observed in any of the challenge or control groups.
authors.affiliation: National Veterinary Institute, Oslo, Norway. soren.grove@vetinst.no
authors.forename: S
authors.initials: S
authors.lastname: Grove
authors.forename: M J
authors.initials: MJ
authors.lastname: Hjortaas
authors.forename: L J
authors.initials: LJ
authors.lastname: Reitan
authors.forename: B H
authors.initials: BH
authors.lastname: Dannevig
mesh_terms: D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000821:virology; D002460:Cell Line; D005393:Fish Diseases / Q000821:virology*; D048389:Gadus morhua / Q000821:virology*; D005814:Genes, Viral; D006321:Heart / Q000821:virology; D007422:Intestines / Q000821:virology; D046829:Isavirus / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D007668:Kidney / Q000821:virology; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013154:Spleen / Q000821:virology; D013997:Time Factors; D014018:Tissue Distribution; D014779:Virus Replication
chemical_list: D012367:RNA, Viral