|
|||||
|
|
Luminal uptake of Vibrio (Listonella) anguillarum by shed enterocytes – a novel early defence strategy in larval fish |
|
| Authors: | A Rekecki E Ringø R Olsen R Myklebust K Dierckens Ø Bergh S Laureau M Cornelissen R Ducatelle A Decostere P Bossier W Van den Broeck |
| Institution: | 1. Department of Morphology, Faculty of Veterinary Medicine, Ghent University, , Merelbeke, Belgium;2. Faculty of Biosciences, Fisheries and Economics, Norwegian College of Fishery Science, University of Troms?, , Breivika, Norway;3. Laboratory of Electron Microscopy, Department of Medical Biology, Faculty of Health Sciences, University of Troms?, , Troms?, Norway;4. Molecular Imaging Centre (MIC), Institute for Biomedicine, University of Bergen, , Bergen, Norway;5. Laboratory of Aquaculture & Artemia Reference Center, Ghent University, , Gent, Belgium;6. Institute of Marine Research, , Bergen, Norway;7. Ecloserie Marine de Gravelines, Voie des Enrochements, , Gravelines, France;8. Department of Anatomy, Embryology and Histology, Ghent University, , Gent, Belgium;9. Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, , Merelbeke, Belgium |
| Abstract: | As adhesion and translocation through fish gut enterocytes of the pathogen Vibrio (Listonella) anguillarum are not well investigated, the effective cause of disease and mortality outbreaks in larval sea bass, Dicentrarchus labrax, suffering from vibriosis is unknown. We detected V. anguillarum within the gut of experimentally infected gnotobiotic sea bass larvae using transmission electron microscopy and immunogold labelling. Intact bacteria were observed in close contact with the apical brush border in the gut lumen. Enterocytes contained lysosomes positive for protein A‐gold particles suggesting intracellular elimination of bacterial fragments. Shed intestinal cells were regularly visualized in the gut lumen in late stages of exposure. Some of the luminal cells showed invagination and putative engulfment of bacterial structures by pseudopod‐like formations. The engulfed structures were positive for protein A‐colloidal gold indicating that these structures were V. anguillarum. Immunogold positive thread‐like structures secreted by V. anguillarum suggested the presence of outer membrane vesicles (MVs) hypothesizing that MVs are potent transporters of active virulence factors to sea bass gut cells suggestive for a substantial role in biofilm formation and pathogenesis. We put forward the hypothesis that MVs are important in the pathogenesis of V. anguillarum in sea bass larvae. |
| Keywords: | bacterial outer membrane vesicles gnotobiotic sea bass immunogold labelling luminal phagocytosis Vibrio anguillarum |