Does virulence assessment of Vibrio anguillarum using sea bass (Dicentrarchus labrax) larvae correspond with genotypic and phenotypic characterization?
BACKGROUND
Vibriosis is one of the most ubiquitous fish diseases caused by bacteria belonging to the genus Vibrio such as Vibrio (Listonella) anguillarum. Despite a lot of research efforts, the virulence factors and mechanism of V. anguillarum are still insufficiently known, in part because of the lack of standardized virulence assays.


RESULTS
We investigated and compared the virulence of 15 V. anguillarum strains obtained from different hosts or non-host niches using a standardized gnotobiotic bioassay with European sea bass (Dicentrarchus labrax L.) larvae as model hosts. In addition, to assess potential relationships between virulence and genotypic and phenotypic characteristics, the strains were characterized by random amplified polymorphic DNA (RAPD) and repetitive extragenic palindromic PCR (rep-PCR) analyses, as well as by phenotypic analyses using Biolog's Phenotype MicroArray™ technology and some virulence factor assays.


CONCLUSIONS
Virulence testing revealed ten virulent and five avirulent strains. While some relation could be established between serotype, genotype and phenotype, no relation was found between virulence and genotypic or phenotypic characteristics, illustrating the complexity of V. anguillarum virulence. Moreover, the standardized gnotobiotic system used in this study has proven its strength as a model to assess and compare the virulence of different V. anguillarum strains in vivo. In this way, the bioassay contributes to the study of mechanisms underlying virulence in V. anguillarum.
Laboratory for Process Microbial Ecology and Bioinspirational Management, PME&BIM, Thomas More Mechelen, Campus De Nayer, Department of Microbial and Molecular Systems, KU Leuven Association, Sint-Katelijne-Waver, Belgium.
Ingeborg
I
Frans
Kristof
K
Dierckens
Sam
S
Crauwels
Ado
A
Van Assche
Jørgen J
JJ
Leisner
Jørgen
J
Leisner
Marianne H
MH
Larsen
Chris W
CW
Michiels
Kris A
KA
Willems
Bart
B
Lievens
Peter
P
Bossier
Hans
H
Rediers
D000818:Animals; D001492:Bass / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D007814:Larva / Q000382:microbiology; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D014733:Vibrio / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence
D004269:DNA, Bacterial