Éditeur(s) : Inter-Research
Résumé : Macrobrachium rosenbergii nodavirus (MrNV) and extra small virus (XSV) were purified from diseased freshwater prawns M rosenbergii and used to infect healthy post-larvae (PL) by an immersion method. Three groups of prawns were challenged with various combined doses of MrNV and XSV. Signs of white-tail disease (WTD) were observed in Groups 1 and 2, which had been challenged with combinations containing relatively high proportions of MrNV and low proportions of XSV. By contrast there was little sign of WTD in Group 3, which had been challenged with a higher proportion of XSV than MrNV. A 2-step Taqman real-time RT-PCR was developed and applied to quantify viral copy numbers in each challenged PL. Results showed that genomic copies of both viruses were much higher in Groups 1 and 2 than they were in Group 3, indicating that MrNV plays a key role in WTD of M rosenbergii. The linear correlation between MrNV and XSV genome copies in infected prawns demonstrated that XSV is a satellite virus, dependent on MrNV, but its role in pathogenicity of WTD remains unclear.
Diseases of aquatic organisms (0177-5103) (Inter-Research), 2006-07 , Vol. 71 , N. 1 , P. 11-17

Droits : Inter-Research 2006
http://archimer.ifremer.fr/doc/2006/publication-3568.pdf
DOI:10.3354/dao071011
http://archimer.ifremer.fr/doc/00000/3568/

Éditeur(s) : Université de Montpellier II
Résumé : Penaeid family shrimp constitute the first aquaculture product in the world in terms of commercial value. They are produced in third world countries of the sub-equatorial belt. Among the causes limiting their production, one is the presence of the WSSV (White Spot Syndrome Virus), a pathogenic agent that produces massive mortality. Our aim was to investigate the first stages of the viral infection, in order to be used as target of prophylactic actions. A fish cell line (SSN-1) was used as model to tentatively develop in vitro studies. Only defective particles were produced confirming the high specificity to crustacea of the infection with crustacean virus. Electron microscopy showed structural similarities between the WSSV and B, B2 and Baculo-B viruses of crabs. This suggests B2 may belong also to the family Nimaviridae, genus Whispovirus. This comparison with B2 virus gives the possibility to understand the role played by the tail-like extension of these viruses in the infectious process by attachment to the plasmic membrane at the beginning of the infection in its specific host.
Les crevettes de grande taille de la famille des Penaeidae constituent le premier produit aquacole en valeur commerciale à l'échelle planétaire. Elles sont produites à 99% dans les pays en voie de développement de la ceinture sub-équatoriale. Parmi les causes limitant leur production, le White Spot Syndrome Virus est l'agent pathogène ayant provoqué le plus des pertes dans le monde. Notre étude a été orientée vers la reconnaissance des premiers stades de l'infection, susceptibles d'être la cible d'une action prophylactique. Nous avons testé l'utilisation d'une lignée cellulaire de poisson SSN-1 afin d'étudier les possibilités d'un développement in vitro. Seules des particules défectives ont été produites confirmant la haute spécificité des infections à virus de crustacés. Les recherches en microscopie électronique ont montré une similarité structurale du WSSV avec les virus (B, B2 et Baculo-B) des crabes. Ceci suggère que ces agents (B2 et WSSV) seraient tout deux de la famille des Nimaviridae et du genre Whispovirus. La comparaison avec le virus B2 permet de comprendre le rôle clef joué par la partie caudale de ces virus dans l'infection par son attachement à la membrane plasmique lors de l'infection chez son hôte spécifique.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2008/these-6650.pdf
http://archimer.ifremer.fr/doc/00000/6650/