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Infectious pancreatic necrosis virus (IPNV) is an unenveloped icosaedrical virus found in fishes of Spain. Restriction fragment length polymorphism (RFLP) analysis yielded seven geno groups and further analyses suggested that the two-step restriction analysis assay is the best method for typing new isolates of aquabirnaviruses aquabirnaviruses.

Comparisons between the biological, serological and molecular characteristics of a group of Vibrio anguillarum-related (VAR) organisms of varied origins and Vibrio anguillarum were undertaken. The studies employed numerical taxonomy, lipopolysaccharide and protein profiles, immunoblot assays and plasmid analysis. The degree of virulence of VAR organisms present in fish was also measured. The study proved that VAR strains connected with infection must be combined with V. anguillarum to develop vaccines against vibriosis.

Pasteurella piscida is the causative agent of pasteurellosis in fish. Phenotypic, antigenic and molecular characterizations were carried out on P. piscida strains representing European, Japanese and American species. The results showed that the geographically separated strains constitute a single taxon based on all criteria analyzed. These results have implications in the development of vaccines as well as DNA hybridization probes for P. piscida.

The potency of a whole-cell bacterin (WCB) and a toxoid enriched whole-cell vaccine (WCEB) administered intraperitoncally into raibow trout, Oncorhynchus mykiss (Richardson), were compared. The most effective vaccine was further evaluated by bathing turbot, Scophthalmus maximus (L). These vaccienes were composed of three strains of V. anguillarum, of the serotypes 01 and 02. Both vaccines conferred the highest protection against strains of serotype 01 within 4 weeks, with the toxoid enriched vaccine giving the best results (77 RPS). When trout were revaceinated after 7 weeks with this vaccine, good protection was achieved against strains of serotypes 01 and 02. Interestingly, when the WCEB was administered by bath to turbot, acceptable levels of protection against strains of both serotypes were obtained after 4 weeks of immunization. [ABSTRACT FROM AUTHOR]

Senegalese sole is susceptible to marine VHSV isolates but is not affected by freshwater isolates, which may indicate differences regarding virus-host immune system interaction. IFN I induces an antiviral state in fish, stimulating the expression of genes encoding antiviral proteins (ISG). In this study, the stimulation of the Senegalese sole IFN I by VHSV infections has been evaluated by the relative quantification of the transcription of several ISG (Mx, Isg15 and Pkr) after inoculation with marine (pathogenic) and freshwater (non-pathogenic) VHSV isolates. Compared to marine VHSV, lower levels of RNA of the freshwater VHSV induced transcription of ISG to similar levels, with the Isg15 showing the highest fold induction. The protective role of the IFN I system was evaluated in poly I:C-inoculated animals subsequently challenged with VHSV isolates. The cumulative mortality caused by the marine isolate in the control group was 68%, whereas in the poly I:C-stimulated group was 5%. The freshwater VHSV isolate did not cause any mortality. Furthermore, viral RNA fold change and viral titers were lower in animals from the poly I:C + VHSV groups than in the controls. The implication of the IFN I system in the protection observed was confirmed by the transcription of the ISG in animals from the poly I:C + VHSV groups. However, the marine VHSV isolate exerts a negative effect on the ISG transcription at 3 and 6 h post-inoculation (hpi), which is not observed for the freshwater isolate. This difference might be partly responsible for the virulence shown by the marine isolate.