Viral infections are detected in most cases by the host innate immune system through pattern-recognition receptors (PRR), sensors for pathogen-associated molecular patterns (PAMPs), which induce production of cytokines, such as type I interferons (IFN). Recent identification mammalian and teleost fish cytoplasmic viral RNA sensors, RIG-I-like (RLRs), their mitochondrial adaptor: antiviral signaling (MAVS) protein, also called IPS-1, highlight important role induction IFN at early stage a...

Abstract Non virion (NV) protein expression is critical for fish Novirhabdovirus, viral hemorrhagic septicemia virus (VHSV) and infectious hematopoietic necrosis (IHNV), in vivo pathogenesis. However, the mechanism by which NV promotes replication still unclear. We developed an approach based on reverse genetics interactomic identified several NV-associated cellular partners underlying pathways as potential targets. Among these cell partners, we showed that proteins specifically interact...

Viral hemorrhagic septicemia virus (VHSV) is a highly contagious leading to high mortality in large panel of freshwater and marine fish species. VHSV isolates originating from show low pathogenicity rainbow trout. The analysis several nearly complete genome sequences displaying varying levels virulence trout suggested that only limited number amino acid residues might be involved regulating the level virulence. Based on recent 55 strains, which were entirely sequenced phenotyped vivo trout,...

ABSTRACT The genome sequence of a hypervirulent novirhabdovirus, viral hemorrhagic septicemia virus (VHSV) French strain 23-75, was determined. Compared to the prototype Fil3 strain, number substitutions, deletions, and insertions were observed. Following establishment plasmid-based minigenome replication assay, recombinant VHSV (rVHSV) successfully recovered. rVHSV exhibits wild-type-like growth properties in vitro as well vivo rainbow trout. dispensable role NV for novirhabdovirus...

We previously reported that betanodavirus reassortant strains [redspotted grouper nervous necrosis virus/striped jack virus (SJNNV)] isolated from Senegalese sole (Solea senegalensis) exhibited a modified SJNNV capsid amino acid sequence, with changes at aa 247 and 270. In the current study, we investigated possible role of both residues as putative virulence determinants. Three recombinant viruses harbouring site-specific mutations in protein rSs160.03247 (S247A), rSs160.03270 (S270N)...

The genome of infectious hematopoietic necrosis virus (IHNV), a salmonid novirhabdovirus, has been engineered to modify the gene order and evaluate impact on possible attenuation in vitro vivo By reverse genetics, eight recombinant IHNVs (rIHNVs), termed NxGy according respective positions nucleoprotein (N) glycoprotein (G) genes along genome, have recovered. All rIHNVs fully characterized for their cytopathic effects, kinetics replication, profiles viral transcription. These are stable...

The outbreaks of viral hemorrhagic septicemia (VHS) and encephalopathy retinopathy (VER) caused by the enveloped novirhabdovirus VHSV, non-enveloped betanodavirus nervous necrosis virus (NNV), respectively, represent two main infectious threats for aquaculture worldwide. Non-segmented negative-strand RNA viruses such as VHSV are subject to a transcription gradient dictated order genes in their genomes. With goal developing bivalent vaccine against NNV infection, genome has been engineered...

Sleeping disease in rainbow trout is characterized by an abnormal swimming behaviour of the fish which stay on their side at bottom tanks. This sign due to extensive necrosis and atrophy red skeletal muscle induced sleeping virus (SDV), also called salmonid alphavirus 2. Infections humans with arthritogenic alphaviruses, such as Chikungunya (CHIKV), are global causes debilitating musculoskeletal diseases. The mechanisms these pathologies poorly understood restrictive availability animal...

Novirhabdoviruses like the Viral hemorrhagic septicemia virus (VHSV) are rhabdoviruses infecting fish. In current study, RNA genomes of different VHSV field isolates classified as high, medium or low virulent phenotypes have been sequenced by next-generation sequencing and compared. Various amino acid changes, depending on phenotype, identified in all proteins. As a starting point, we focused our study non-virion (NV) non-structural protein which an arginine residue (R116) is present...

A recombinant sleeping disease virus (rSDV) was previously shown to be totally attenuated and provide long-term protection in trout (C. Moriette, M. Leberre, A. Lamoureux, T. L. Lai, Brémont, J. Virol. 80:4088-4098, 2006). Sequence comparison of the rSDV wild-type genomes exhibited a number nucleotide changes. In current study, we demonstrate that virulent phenotype SDV essentially associated with two amino acid changes, V8A M136T, E2 glycoprotein, change mostly being involved acquisition phenotype.

Infectious haematopoietic necrosis virus (IHNV) and spring viraemia of carp (SVCV) are both rhabdoviruses fish, listed as notifiable disease agents by the World Organization for Animal Health. Recombinant with heterologous gene substitutions have been engineered to study genetic determinants assess potential these recombinant viruses vaccine development. A IHNV (rIHNV), containing full-length genome a European strain, was modified deleting glycoprotein (G) replacing it SVCV G-gene make...

In this study, we aimed to characterize the epitope recognized by neutralizing 17H23 mAb directed against E2 glycoprotein of most salmonid alphavirus (SAV) subtypes and widely used in several laboratories routinely diagnose SAV. We hypothesized that was located major domain B, previously identified mammalian alphaviruses as mAbs. Indeed, SAV B counterpart is contained protein characterized being 17H23. Thus, precisely epitope, developed an alanine scanning mutagenesis approach coupled with...

West Nile Virus (WNV) is a zoonotic mosquito-transmitted flavivirus that can infect and cause disease in mammals including humans. Our study aimed at developing WNV vectored vaccine based on fish Novirhabdovirus, the Viral Hemorrhagic Septicemia virus (VHSV). VHSV replicates temperatures lower than 20°C naturally inactivated higher temperatures. A reverse genetics system has recently been developed our laboratory for allowing addition of genes viral genome recovery respective recombinant...

Novirhabdoviruses like Viral Hemorrhagic Septicemia Virus (VHSV) and Infectious Hematopoietic Necrosis (IHNV) are fish-infecting Rhabdoviruses belonging to the Mononegavirales order. By reverse genetics, we previously showed that a recombinant VHSV expressing West Nile (WNV) E glycoprotein could serve as vaccine platform against WNV. In current study, aimed evaluate potential of Novirhabdovirus influenza virus. Recombinant Novirhabdoviruses, rVHSV-HA rIHNV-HA, at viral surface hemagglutinin...

The first salmonid alphaviruses, Salmon pancreas disease virus (SPDV) and Sleeping (SDV), were discovered molecularly characterized over 15 years ago. This chapter presents an update on what is known of the molecular biology these viruses, diagnostics tools that have been developed, more recent epidemiological studies, existing possible future vaccines to fight against emerging viruses. Salmonid alphavirus (SAV) now classified into three subtypes: SAV1 causing in salmon Ireland Scotland;...

Interferons are the first lines of defense against viral pathogen invasion during early stages infection. Their synthesis is tightly regulated to prevent excessive immune responses and possible deleterious effects on host organism itself. The RIG-I-like receptor signaling cascade one major pathways leading production interferons. This pathway amplifies danger signals mounts an appropriate innate response but also needs be finely allow a rapid return homeostasis. Recent advances have...

Spring viremia of carp virus (SVCV) has a broad fish host spectrum and is responsible for disease that generally affects juvenile fishes with mortality rate up to 90%. In the absence treatments or vaccines against SVCV, search prophylactic therapeutic solutions thus relevant, particularly identify compatible mass vaccination. addition being threat aquaculture ecosystems, SVCV unique pathogen study virus-host interactions in zebrafish model. Establishing first reverse genetics system design...

Viral haemorrhagic septicaemia virus (VHSV) is the cause of an important listed disease in European rainbow trout (Oncorhynchus mykiss) aquaculture and can be present a wide range fish species, including marine fish, which act as viral reservoir. Recent studies revealed putative genetic virulence markers VHSV to highlighting roles nucleoprotein, phosphoprotein non-virion protein. Using reverse genetics, we produced recombinant viruses by introducing parts or entire nucleoprotein from...

Salmonid alphavirus (SAV) is an atypical that has a considerable impact on salmon and trout farms. Unlike other alphaviruses, such as the chikungunya virus, SAV transmitted without arthropod vector, it does not cause cell shutoff during infection. The mechanisms by which escapes host immune system remain unknown. By studying role of proteins RIG-I signaling cascade, first line defense infection, we demonstrated nonstructural protein 2 (nsP2) effectively blocks induction type I interferon...

We have generated defective Viral Hemorrhagic Septicemia Viruses (VHSV) which express either the green fluorescent protein (GFP) or a far-red (mKate) by replacing genes encoding nucleoprotein N polymerase-associated P protein. To recover viable viruses, rVHSV-ΔN-Red and rVHSV-ΔP-Green, fish cells were co-transfected with both deleted cDNA VHSV genomes, together plasmids expressing N, L of RNA-dependent RNA polymerase. After one passage transfected cell supernatant, red foci observed. titer...