title: Zebrafish larvae are unable to mount a protective antiviral response against waterborne infection by spring viremia of carp virus.
abstract: Interferons (IFNs) and their receptors exist in all classes of vertebrates, where they represent early elements in innate and adaptive immunity. Both types I and II IFNs have been discovered in fish and type I IFN has recently been classified into two groups based on their primary protein sequences and biological activities. Thus, although groups I and II zebrafish IFN show powerful antiviral activities, only group I (IFNphi1) is able to protect the fish against bacterial infection. In addition, group II IFNs (IFNphi2 and IFNphi3) induce a rapid and transient expression of antiviral genes, while group I IFN exerts a slow but more powerful induction of several antiviral and pro-inflammatory genes. To gain further insight into the IFN system of fish, we have developed a waterborne infection model of zebrafish larvae with the spring viremia of carp virus (SVCV). Larvae were challenged 3 days post-fertilization by immersion, which considerably reduces the manipulation of fish and represents a more natural route of infection. Using this infection model, we unexpectedly found an inability on the part of zebrafish larvae to mount a protecting antiviral response to waterborne SVCV. Nevertheless, zebrafish larvae showed a functional antiviral system since ectopic expression of the cDNA of both groups I and II IFN was able to protect them against SVCV via the induction of IFN-stimulated genes (ISGs). Interestingly, group II IFNs also induced group I IFN, suggesting crosstalk between these two kinds of antiviral IFN. These results further confirm the antiviral activities of type I IFN in the zebrafish and provide the first viral infection model for zebrafish larvae using a natural route of infection. This model, in combination with the powerful gene overexpression and morpholino-mediated knockdown techniques, will help to illuminate the IFN system of teleost fish.
authors.affiliation: Department of Cell Biology and Histology, Faculty of Biology, University of Murcia, Murcia, Spain.
authors.forename: Azucena
authors.initials: A
authors.lastname: López-Muñoz
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Roca
authors.forename: María P
authors.initials: MP
authors.lastname: Sepulcre
authors.forename: José
authors.initials: J
authors.lastname: Meseguer
authors.forename: Victoriano
authors.initials: V
authors.lastname: Mulero
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation; D007113:Immunity, Innate / Q000235:genetics; D007370:Interferon Type I / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D007814:Larva / Q000276:immunology / Q000821:virology; D012209:Rhabdoviridae / Q000276:immunology* / Q000472:pathogenicity; D018353:Rhabdoviridae Infections / Q000276:immunology*; D019076:Transgenes / Q000235:genetics; D014774:Virulence; D015027:Zebrafish / Q000254:growth & development / Q000276:immunology
chemical_list: D016207:Cytokines; D029941:Fish Proteins; D007370:Interferon Type I; D007371:Interferon-gamma