title: IPNV modulation of pro and anti-inflammatory cytokine expression in Atlantic salmon might help the establishment of infection and persistence.
abstract: IPNV is the agent of a well-characterized acute disease that produces a systemic infection and high mortality in farmed fish species and persistent infection in surviving fish after outbreaks. Because modulation of the host expression of pro and anti-inflammatory cytokines can help establish persistence, in this study, we examined the expression of IL-1β, IL-8, IFNα1 and IL-10 during acute and persistent IPNV infection of Atlantic salmon. Results showed that IPNV infection induces an increase of the IFNα1 and IL-10 mRNA levels in the spleen and head kidney (HK) of fish after acute experimental infection. Levels of the pro-inflammatory cytokines IL-1β and IL-8 did not rise in the spleen although an increase of IL-1β, but not of IL-8, was observed in head kidney. In carrier asymptomatic salmon, cytokine gene expression of IFNα1 in the spleen and IL-10 in head kidney were also significantly higher than expression in non-carrier fish. Interestingly, a decrease of IL-8 expression was also observed. IPNV infection of SHK-1, which is a macrophage-like cell line of salmon, also induced an increase of expression of the anti-inflammatory cytokine IL-10 with no effects on the expression of IL-1β and IL-8. The effects are induced by an unknown mechanism during viral infection because poly I:C and the viral genomic dsRNA showed the opposite effects on cytokine expression in SHK-1 cells. In summary, IPNV always induces up-regulation of the anti-inflammatory cytokine IL-10 in Atlantic salmon. As this is accompanied by a lack of induction of the pro-inflammatory cytokines IL-1β and IL-8, the anti-inflammatory milieu may explain the high frequency, prevalence and persistence of IPNV in salmon. Effects might be part of the viral mechanisms of immune evasion.
authors.affiliation: Laboratorio de Inmunología, Centro de Biotecnología Acuícola, Facultad de Química y Biología, Universidad de Santiago de Chile, Chile.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Reyes-Cerpa
authors.forename: Felipe E
authors.initials: FE
authors.lastname: Reyes-López
authors.forename: Daniela
authors.initials: D
authors.lastname: Toro-Ascuy
authors.forename: Jorge
authors.initials: J
authors.lastname: Ibañez
authors.forename: Kevin
authors.initials: K
authors.lastname: Maisey
authors.forename: Ana María
authors.initials: AM
authors.lastname: Sandino
authors.forename: Mónica
authors.initials: M
authors.lastname: Imarai
mesh_terms: D000818:Animals; D018175:Birnaviridae Infections / Q000276:immunology / Q000662:veterinary*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D005393:Fish Diseases / Q000276:immunology* / Q000821:virology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005880:Gills / Q000276:immunology; D060226:Head Kidney / Q000276:immunology; D018061:Infectious pancreatic necrosis virus / Q000502:physiology*; D020317:Salmo salar
chemical_list: D016207:Cytokines