title: Molecular epidemiology of betanodaviruses isolated from sea bass and sea bream cultured along the Tunisian coasts.
abstract: Viral nervous necrosis (VNN) is a serious viral disease affecting farmed sea bass (Dicentrarchus labrax). Only scarce molecular data are available on the disease-causing betanodavirus populations in Tunisia. Therefore, we carried out the first molecular survey of betanodaviruses in farmed sea bass and sea bream (Sparus aurata) along the Tunisian coasts. Among 81 samples from five farms, 20 tested positive with RT-PCR, not only in clinical cases but also in asymptomatic fish before and during outbreaks. Positive fish were found in all farms, except in one farm investigated in the south of Tunisia. Sequencing the fragments of both genomic components (RNA1 and RNA2) in 16 isolates revealed that the Tunisian viruses were related to the red-spotted grouper nervous necrosis virus (RGNNV) genotype. Furthermore, the newly sequenced isolates were generally highly related to one another suggesting a recent common ancestor. They also showed high identities with other isolates obtained from wild fishes in the Mediterranean, but were slightly more divergent from strains recently obtained from farmed fishes in the Mediterranean. The poor genetic diversity of the viral population along the Tunisian coasts is striking. One hypothesis is that it is the result of the maintenance of a homogenous genetic pool among infected wild fish, groupers for instance and subsequent dissemination to farmed fish over the seasons.
authors.affiliation: Laboratoire de Virologie, Institut de la Recherche Vétérinaire de Tunisie, Université Tunis-El Manar, 20, rue Djebel Lakhdar-La Rabta, 1006, Tunis, Tunisia. sondes_hadded@yahoo.fr
authors.forename: Sondès
authors.initials: S
authors.lastname: Haddad-Boubaker
authors.forename: Laurent
authors.initials: L
authors.lastname: Bigarré
authors.forename: Nadia
authors.initials: N
authors.lastname: Bouzgarou
authors.forename: Aida
authors.initials: A
authors.lastname: Megdich
authors.forename: Marine
authors.initials: M
authors.lastname: Baud
authors.forename: Joëlle
authors.initials: J
authors.lastname: Cabon
authors.forename: Noureddine Ben
authors.initials: NB
authors.lastname: Chéhida
mesh_terms: D000818:Animals; D017756:Aquaculture; D001492:Bass / Q000821:virology*; D005393:Fish Diseases / Q000453:epidemiology* / Q000821:virology*; D005838:Genotype; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D030381:Nodaviridae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012327:RNA Virus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D021541:Sea Bream / Q000821:virology*; D017422:Sequence Analysis, DNA; D014416:Tunisia / Q000453:epidemiology
chemical_list: D012367:RNA, Viral