Characterization of the IFN pathway in the teleost fish gonad against vertically transmitted viral nervous necrosis virus.
One of the most powerful innate immune responses against viruses is mediated by type I IFN. In teleost fish, it is known that virus infection triggers the expression of ifn and many IFN-stimulated genes, but the viral RNA sensors and mediators leading to IFN production are scarcely known. Thus, we have searched for the presence of these genes in gilt-head sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax), and evaluated their expression after infection with viral nervous necrosis virus (VNNV) in the brain, the main viral target tissue, and the gonad, used to transmit the virus vertically. In sea bream, a fish species resistant to the VNNV strain used, we found an upregulation of the genes encoding MDA5 (melanoma differentiation-associated gene 5), TBK1 (TANK-binding kinase 1), IRF3 (IFN regulatory factor 3), IFN, Mx [myxovirus (influenza) resistance protein] and PKR (dsRNA-dependent protein kinase receptor) proteins in the brain, which were unaltered in the gonad and could favour the dissemination by gonad fluids or gametes. Strikingly, in European sea bass, a very susceptible species, we also identified, transcripts coding for LGP2 (Laboratory of Genetics and Physiology 2), MAVS (mitochondrial antiviral signalling), TRAF3 (TNF receptor-associated factor 3), TANK (TRAF family member-associated NFκB activator) and IRF7 (IFN regulatory factor 7), and found that all the genes analysed were upregulated in the gonad, but only mda5, lgp2, irf3, mx and pkr were upregulated in the brain. These findings supported the notion that the European sea bass brain innate immune response is unable to clear the virus and pointed to the importance of gonad immunity to control the dissemination of VNNV to the progeny--an aspect that is worth investigating in aquatic animals.
Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n, Puerto de Mazarrón, 30860 Murcia, Spain.
Yulema
Y
Valero
Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain.
Patricia
P
Morcillo
Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain.
José
J
Meseguer
Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Italy.
Francesco
F
Buonocore
Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain.
María A
MA
Esteban
Centro Oceanográfico de Murcia, Instituto Español de Oceanografía (IEO), Carretera de la Azohía s/n, Puerto de Mazarrón, 30860 Murcia, Spain.
Elena
E
Chaves-Pozo
Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, 30100 Murcia, Spain.
Alberto
A
Cuesta
D000818:Animals; D001492:Bass; D001921:Brain / Q000276:immunology / Q000821:virology; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology* / Q000635:transmission / Q000821:virology; D029941:Fish Proteins / Q000235:genetics / Q000276:immunology*; D006066:Gonads / Q000276:immunology* / Q000821:virology; D007113:Immunity, Innate; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000276:immunology*; D007372:Interferons / Q000235:genetics / Q000276:immunology*; D030381:Nodaviridae / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D012327:RNA Virus Infections / Q000276:immunology* / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D021541:Sea Bream; D015398:Signal Transduction
D029941:Fish Proteins; D050838:Interferon Regulatory Factor-3; D007372:Interferons