Infectious salmon anaemia virus replication and induction of alpha interferon in Atlantic salmon erythrocytes

• Published in: Virology Journal
• Main Authors: Groman David B, Wadowska Dorota W, Wright Glenda M, Kibenge Molly JT, Workenhe Samuel T, Kibenge Frederick SB
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2008
• Subjects: Infectious and parasitic diseases; RC109-216; Atlantic salmon
• Online Access: https://doi.org/10.1186/1743-422X-5-36; https://doaj.org/article/5714cdf006ca4b98bca79910288784e5

Abstract Background Infectious salmon anaemia (ISA) virus (ISAV), which causes ISA in marine-farmed Atlantic salmon, is an orthomyxovirus belonging to the genus Isavirus , family Orthomyxoviridae . ISAV agglutinates erythrocytes of several fish species and it is generally accepted that the ISAV receptor destroying enzyme dissolves this haemagglutination except for Atlantic salmon erythrocytes. Recent work indicates that ISAV isolates that are able to elute from Atlantic salmon erythrocytes cause low mortality in challenge experiments using Atlantic salmon. Previous work on ISAV-induced haemagglutination using the highly pathogenic ISAV strain NBISA01 and the low pathogenic ISAV strain RPC/NB-04-0851, showed endocytosis of NBISA01 but not RPC/NB-04-0851. Real-time RT-PCR was used to assess the viral RNA levels in the ISAV-induced haemagglutination reaction samples, and we observed a slight increase in viral RNA transcripts by 36 hours in the haemagglutination reaction with NBISA01 virus when the experiment was terminated. However, a longer sampling interval was considered necessary to confirm ISAV replication in fish erythrocytes and to determine if the infected cells mounted any innate immune response. This study examined the possible ISAV replication and Type I interferon (IFN) system gene induction in Atlantic salmon erythrocytes following ISAV haemagglutination. Results Haemagglutination assays were performed using Atlantic salmon erythrocytes and one haemagglutination unit of the two ISAV strains, NBISA01 and RPC/NB-04-0851, of differing genotypes and pathogenicities. Haemagglutination induced by the highly pathogenic NBISA01 but not the low pathogenic RPC/NB-04-0851 resulted in productive infection as evidenced by increased ISAV segment 8 transcripts and increase in the median tissue culture infectious dose (TCID 50 ) by 5 days of incubation. Moreover, reverse transcription (RT) quantitative PCR used to compare mRNA levels of key Type I IFN system genes in erythrocyte lysates of haemagglutination reactions ...