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Immunisation by intraperitoneal injection of an oil-emulgated recombinant partial capsid protein (rT2) from striped jack nervous necrosis virus (SJNNV) was performed on adult turbot Scophthalmus maximus and Atlantic halibut Hippoglossus hippoglossus. A specific humoral immune response was recorded in both species, and the levels of rT2-specific antibodies increased markedly in all groups during the 20 wk experiment. A challenge model for SJNNV was established by intramuscular injection of juvenile turbot. The turbot developed viral encephalopathy and retinopathy (VER), also known as viral nervous necrosis (VNN), with cumulative mortality in the range of 25 to 66%, after intramuscular inoculation with SJNNV propagated in the striped snake head cell line (SSN-1). Although neither clinical signs nor mortality were registered, SJNNV was neuroinvasive after bath exposure. The infection after both modes of challenge was verified by means of immunohistochemistry and RT-PCR, and SJNNV was reisolated in cell culture. The results indicate that SJNNV may have entered the central nervous system (CNS) by axonal transport through motor nerves after intramuscular inoculation. A vaccine efficacy test was performed on juvenile turbot, employing oil emulsified rT2 as a test vaccine and intramuscular inoculation of SJNNV. Significant protection was observed when the challenge was performed 10 wk post-vaccination. KEY WORDS: Viral encephalopathy and retinopathy (VER) · Nodavirus · Challenge model · Recombinant vaccine · Turbot · Atlantic halibut Resale or republication not permitted without written consent of the publisherDis Aquat Org 45: [33][34][35][36][37][38][39][40][41][42][43][44] 2001 The causative agents of VER are viruses belonging to the Nodaviridae (Mori et al. 1992, Comps et al. 1994. These viruses are unenveloped and icosahedral, with diameters of approximately 25 nm. Their bipartite genomes consist of single-stranded, positive-sense nonpolyadenylated RNA molecules, encoding the putative RNA-dependent RNA polymerase (RNA1) (Nagai & Nishizawa 1999) and the capsid protein precursor (RNA2) (Nishizawa et al. 1995).It has been demonstrated that the broodstock of some teleost species act as reservoirs of nodavirus by shedding viruses through gonadal fluids and infecting offspring (Mushiake et al. 1994, Yoshimizu et al. 1997. Prophylaxis of VER in striped jack Pseudocaranx dentex, barfin flounder Verasper moseri and Japanese flounder Paralychthys olivaceus has been attempted through prevention of vertical transmission by selection of non-carrier spawners identified by RT-PCR on gonadal fluids (Mushiake et al. 1994) or by serodiagnostic methods (Mushiake et al. 1993, Yoshimizu et al. 1997. Although prevention of the disease during larval and juvenile stages may be possible through broodstock management and disinfection of hatchery water, nodavirus in the environment may infect the fish when they are transferred to on-growing sites. Particularly in species whose adult fish are susceptible to VER, additional means ...

In this investigation, the efficacy of a single intraperitoneal injection of flumequine in the treatment of systemic vibriosis in corkwing wrasse Symphodus melops was examined. In a population of corkwing wrasse that was experiencing daily mortality, the dominant bacterium cultivated from kidney samples of dead fish was tentatively classified as a species of Vibrio resembling V. splendidus. The infected fish were randomly divided into two groups, each of 60 individuals. Group 1 was treated with flumequine (25 mg/kg of fish) administered by a single intraperitoneal injection, whereas the fish from group 2 were injected with saline. The mortality was observed daily for 21 d. The cumulative mortality was significantly (P < 0.005) higher in the control group (58%) compared with the medicated group (11%). Bacterial examination of kidneys from dead and surviving fish of both groups indicated the Vibrio to be quickly and effectively eliminated by the antibacterial agent.

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