Experimental infection of turbot, Scophthalmus maximus (L.), by Moritella viscosa, vaccination effort and vaccine‐induced side‐effects

Abstract

Moritella viscosa is the causative agent of winter ulcers in farmed salmonids and Atlantic cod in countries around the North Atlantic. The bacterium has also been isolated from various marine fish species. Bacterial diseases have been a limiting factor in farming of turbot, but M. viscosa has not so far been isolated. In this study, turbot was shown to be sensitive to M. viscosa infection in experimental challenges. Pathological changes in infected turbot were comparable with those previously described for winter ulcers in salmon. A multivalent commercial salmon vaccine, containing M. viscosa as one of five antigens and a mineral oil adjuvant, did not protect turbot against challenge 13 weeks post-vaccination. Weight gain of vaccinated turbot compared with controls was not reduced 7 weeks post-vaccination. Vaccination did not induce a specific anti-M. viscosa response, while elevated anti-M. viscosa antibody levels were detected both in vaccinated and unvaccinated fish 5 weeks post-challenge. The vaccine did, however, induce an antibody response against Aeromonas salmonicida, another vaccine component. Minor intra-abdominal adhesions were detected in vaccinated fish and fish injected with a mineral oil adjuvant. The measurement of various innate humoral immune parameters did not reveal significant differences between vaccinated and control groups.

Isolation and experimental infection with Vibrio alginolyticus in the sea horse, Hippocampus reidi Ginsburg, 1933 (Osteichthyes: Syngnathidae) in Brazil

“…In infected fish hyperplasia, necrotic foci, sinusoidal and bile duct deformation (Figure 2g,h) were found. Our results corroborated the observations in brill Colistium guntheri suffering from septicemic bacterial by V. campbellii (Diggles et al, 2000) and in turbot infected by Moritella viscosa (Björnsdóttir et al, 2004). The liver is an organ that may be used as an indicator of alterations in nutritional or physiological status as commented by Segner and Juario (1986).…”

Antibody responses of turbot Psetta maxima against various antigen formulations of scuticociliates Ciliophora

“…Polyvalent vaccines have been used for some bacterial diseases in fish, although inhibition of the specific responses can occur (Nikoskelainen et al 2007). The absence of protection against some bacteria included in polyvalent turbot vaccines has also been reported (Björnsdóttir et al 2004(Björnsdóttir et al , 2005. In the present work, no advantage was obtained using the V5 ciliate preparation.…”

Atlantic salmon bath challenged with Moritella viscosa – Pathogen invasion and host response

“…In cross-species challenge experiments using M. viscosa isolated from diseased Atlantic salmon (Salmo salar), turbot (Scophthalmus maximus) and cod (Gadus morhua) were found to be susceptible to infection, while Atlantic halibut (Hippoglossus hippoglossus) was more resistant [4,5]. In addition to strains isolated from Atlantic salmon and rainbow trout (Oncorhynchus mykiss), M. viscosa has also been isolated from farmed cod [6] and wild lumpsucker (Cyclopterus lumpus) [7].…”