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Persistent infections with infectious pancreatic necrosis virus ( IPNV ) of different virulence in Atlantic salmon, Salmo salar L
Author(s) -
Julin K,
Johansen LH,
Sommer AI,
Jørgensen J B
Publication year - 2015
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.12317
Subject(s) - infectious pancreatic necrosis virus , biology , salmo , virus , virulence , virology , outbreak , immune system , pathogen , innate immune system , microbiology and biotechnology , immunology , fishery , fish <actinopterygii> , gene , genetics
Infectious pancreatic necrosis virus ( IPNV ) is a prevalent pathogen in fish worldwide. The virus causes substantial mortality in Atlantic salmon juveniles and smolts when transferred to sea water and persistent infection in surviving fish after disease outbreaks. Here, we have investigated the occurrence of the virus as well as the innate immune marker Mx in the head kidney ( HK ) of Atlantic salmon throughout an experimental challenge covering both a fresh and a seawater phase. The fish were challenged with a high ( HV ) and low virulence ( LV ) IPNV . Both isolates caused mortality due to reactivation of the virus after transfer to sea water. In the freshwater phase, higher levels of virus transcripts were detected in the HK of fish infected with LV IPNV compared to HV , suggesting that the HV isolate is able to limit its own replication to a level where the innate immune system is not alerted. Further, ex vivo HK leucocytes derived from fish infected with the two isolates were stimulated with CpG DNA . Significantly, higher IFN levels were found in the LV compared to the HV group in the freshwater phase. This suggests that the viruses attenuate the antiviral host immune response at different levels which may contribute to the observed differences in disease outcome.