title: In vitro and in vivo characterization of molecular determinants of virulence in reassortant betanodavirus.
abstract: We previously reported that betanodavirus reassortant strains [redspotted grouper nervous necrosis virus/striped jack nervous necrosis 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 the possible role of both residues as putative virulence determinants. Three recombinant viruses harbouring site-specific mutations in the capsid protein sequence, rSs160.03247 (S247A), rSs160.03270 (S270N) and rSs160.03247+270 (S247A/S270N), were generated using a reverse genetics system. These recombinant viruses were studied in cell culture and in vivo in the natural fish host. The three mutant viruses were shown to be infectious and able to replicate in E-11 cells, reaching final titres similar to the WT virus, although with a somewhat slower kinetics of replication. When the effect of the amino acid substitutions on virus pathogenicity was evaluated in Senegalese sole, typical clinical signs of betanodavirus infection were observed in all groups. However, fish mortality induced by all three mutant viruses was clearly affected. Roughly 40 % of the fish survived in these three groups in contrast with the WT virus which killed 100 % of the fish. These data demonstrated that aa 247 and 270 play a major role in betanodavirus virulence although when both mutated aa 247 and 270 are present, corresponding recombinant virus was not further attenuated.
authors: Instituto de Acuicultura, Universidad de Santiago de Compostela, A Coruña, Spain.
authors: Sandra
authors: S
authors: Souto
authors: Unité de Virologie et Immunologie Moléculaires, INRA, Jouy en Josas, France.
authors: Emilie
authors: E
authors: Mérour
authors: Unité de Virologie et Immunologie Moléculaires, INRA, Jouy en Josas, France.
authors: Stéphane
authors: S
authors: Biacchesi
authors: Unité de Virologie et Immunologie Moléculaires, INRA, Jouy en Josas, France.
authors: Michel
authors: M
authors: Brémont
authors: Instituto de Acuicultura, Universidad de Santiago de Compostela, A Coruña, Spain.
authors: José G
authors: JG
authors: Olveira
authors: Instituto de Acuicultura, Universidad de Santiago de Compostela, A Coruña, Spain.
authors: Isabel
authors: I
authors: Bandín
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D005393:Fish Diseases / Q000473:pathology* / Q000821:virology*; D005412:Flatfishes / Q000821:virology; D020125:Mutation, Missense; D030381:Nodaviridae / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology*; D017354:Point Mutation; D012327:RNA Virus Infections / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D016865:Reassortant Viruses / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology*; D059386:Reverse Genetics; D016019:Survival Analysis; D019562:Viral Load; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D037521:Virulence Factors