Abstract
Severe economic losses due to diseases in marine larviculture may be linked to vibriosis. To better understand the pathogenesis of vibriosis and evaluate new ways to prevent and combat this important disease, there is a great need for reliable and reproducible experimental infection models. The present study aimed at developing a challenge model for vibriosis in Dover sole larvae and testing its applicability to study the effect of the probiotic treatment. For that purpose, larvae were challenged at 10 days post hatching with Vibrio anguillarum WT, V. anguillarum HI610 or V. harveyi WT. Following administration of V. anguillarum WT via immersion at 1 × 107 colony forming units/mL, a larval mortality of 50% was observed at 17 days post-inoculation. In a next step, the probiotic potential of 371 isolates retrieved from Dover sole was assessed by screening for their inhibitory effects against Vibrio spp. and absence of haemolytic activity. One remaining isolate (V. proteolyticus) and V. lentus, known for its protective characteristics in seabass larvae, were further tested in vivo by means of the pinpointed experimental infection model. Neither isolate provided via the water or feed proved to be protective for the Dover sole larvae against challenge with V. anguillarum WT. This developed challenge model constitutes a firm basis to expedite basic and applied research regarding the pathogenesis and treatment of vibriosis as well as for studying the impact of (a)biotic components on larval health.
Highlights
Dover sole (Solea solea L.) is greatly appreciated in high quality restaurants and has a high market value, making it a very promising candidate for European aquaculture [1, 2]
Experimental infection model In the first challenge experiment to develop the infection model, no significant difference in survival at 17 dph was observed between the negative control group and the larvae inoculated with 105 colony forming units (CFU)/ mL V. anguillarum HI610 (OR = 0.66, 95% CI [0.26;1.66], p = 0.367), V. anguillarum WT (OR = 0.56, 95% CI [0.23;1.37], p = 0.195) and V. harveyi (OR = 1.55, 95% CI [0.52;4.64], p = 0.423)
In the second challenge experiment, no significant difference in survival at 17 dph was noted between the negative control group and the larvae inoculated with 106 CFU/mL V. anguillarum HI610 (OR = 1.48, 95% CI [0.53;4.16], p = 0.448) or V. harveyi WT (OR = 0.90, 95% CI [0.36;2.27], p = 0.817)
Summary
Dover sole (Solea solea L.) is greatly appreciated in high quality restaurants and has a high market value, making it a very promising candidate for European aquaculture [1, 2]. The emerging antimicrobial resistance, De Swaef et al Vet Res (2018) 49:24 the potential transfer of antimicrobial resistance genes to fish or human pathogens [14] and the possibility that antimicrobials can enter the human food chain [15], stress the need to develop reliable alternatives These latter should ensure a healthy microbial environment in the larval rearing tanks and decrease disease and mortality [16]. There is a clear paucity of information in our understanding of the mode of action of probiotics and their interaction with the aquatic organism especially in the marine larval stage [20, 23, 24] To remediate this and to elucidate the mechanism by which these treatments exert their beneficial impact, more knowledge on how the bacterium interacts with its host and causes disease is needed. A reproducible and reliable experimental infection model eliciting vibriosis is nonexisting, hampering in-depth research on the interplay between Vibrio and its larval host
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
