Protection of rainbow trout against vibriosis and furunculosis by the use of attenuated strains of Vibrio anguillarum

Abstract

The fish pathogen Vibrio anguillarum causes a lethal infection in rainbow trout (Salmo gairdneri). Three different avirulent mutants, constructed by transposon insertion mutagenesis (VAN20 and VAN70) or as antibiotic-resistant mutants (VAN1000), were isolated by screening 200 individual isolated mutants for avirulence. When used as live vaccines, all three avirulent mutants were able to induce protective immunity against the homologous as well as a heterologous strain of V. anguillarum. When VAN1000 was used, protective immunity could be recorded 1 week after bath vaccination with 107 bacteria per ml of water for 30 min. A single-dose immunization was effective for at least 12 weeks. Western immunoblotting showed that strains of V. anguillarum have antigenic determinants in common with Aeromonas strains. Therefore, we tested and confirmed that VAN1000 also was able to induce protective immunity against challenge with Aeromonas salmonicida.

A comprehensive review of Vibrio (Listonella) anguillarum: ecology, pathology and prevention

“…Vibriosis vaccines can also be delivered by injection in the form of monoclonal anti-idiotype antibodies as surrogate antigens which induce protective immunity against V. anguillarum in fish (Yongjuan et al 2002) and outer-membrane antigens derived from adhesion proteins of Aeromonas hydrophila are also applicable as immunization factors against vibriosis (Fang et al 2000). Live-attenuated vaccines have been developed in which V. anguillarum cultures are mutated but remain viable for effective immunization in fish (Norqvist et al 1989). Plasmid-free V. anguillarum strains are strong candidates for attenuated vaccines and can be genetically modified to produce foreign proteins which enhance immunization in fish depending on the expressed secretion (Shao et al 2005).…”

Chemotactic motility is required for invasion of the host by the fish pathogen Vibrio anguillarum

“…Rainbow trout (Onchorynchus mykiss) weighing approximately 10 to 15 g were infected with V. anguillarum either by intraperitoneal injections or by immersion of fish in water containing bacteria, as previously described (Norqvist et al, 1989). The initial screening of the non-motile mutants for virulence consisted of exposing five fish to a fixed amount of bacteria.…”

Chemotaxis of Vibrio anguillarum to fish mucus: role of the origin of the fish mucus, the fish species and the serogroup of the pathogen

“…Di¡erences in the a Reported previously. Pathogenicity of strain NB10 was studied in rainbow trout (Salmo gairdneri) [17]. Pathogenicity of the other strains was studied in Atlantic salmon (Salmo salar L.) [19].…”

“…b From American Type Culture Collection, Rockville, MD, USA. c [17]. d From a culture collection at the Royal Veterinary and Agricultural University, Frederiksberg, Denmark.…”