Is the turbot, Scophthalmus maximus (L.), intestine a portal of entry for the fish pathogen Vibrio anguillarum?

Abstract

The role of the intestinal tract in Vibrio anguillarum infection of turbot, Scophthalmus maximus (L.), fingerlings was investigated in two in vivo models and the possible mechanisms involved were studied in vitro. Viable V. anguillarum cells were detected in spleens from more than 50% of the fish administered the pathogen orally or rectally, suggesting that the intestinal tract is a portal of entry for V anguillarum. In transmission electron micrographs, V. anguillarumlike cells were seen close to the rectal epithelium, suggesting penetration of the mucus layer, but no epithelial cell penetration or endocytosis was evident. Attachment to intact turbot intestines was investigated, and 80% or mote of the bacterial cells still remained attached after serial washings. A significantly higher number of cells attached to rectal segments than to the other intestinal segments. In vitro, V. anguillarum cells did not adhere specifically to intestinal mucus, but rather accumulated close to intestinal mucus interfaces and subsequently penetrated them. It is proposed that the intestinal tract of turbot is a portal of entry for V. anguillarum and that the cells penetrate the intestinal mucus overlaying the epithelial cells.

Role for the major outer-membrane protein from Vibrio anguillarum in bile resistance and biofilm formation

“…Resistance to bile should be critical for V. anguillarum to colonize the intestines of the fish host (Horne & Baxendale, 1983;Olsson et al, 1996Olsson et al, , 1998. Therefore, it is puzzling why the ompU mutant was not decreased in virulence.…”

“…anguillarum has been shown to utilize the intestines as a site of attachment, colonization and proliferation (Horne & Baxendale, 1983;Olsson et al, 1996Olsson et al, , 1998 , respectively. These results indicate that ompU is not essential for V. anguillarum to cause disease in fish.…”

Biochemical characterization of different types of adherence of Vibrio species to fish epithelial cells

“…It has been postulated that the portals of entry for Vibrio species into fish are the gastrointestinal tract (Horne & Baxendale, 1983 ;Kanno et al, 1989 ;Olsson et al, 1996), gills (Baudin-Laurencin & German, 1987) and skin (Grimes et al, 1985 ;Kanno et al, 1989). Regardless of the route vibrios use to enter the fish, it is necessary for them to adhere to and penetrate through the epithelial cells to spread systemically.…”

Immune response in Lutjanus erythropterus induced by the major outer membrane protein (OmpU) of Vibrio alginolyticus

“…Resistance to bile is important for bacteria to colonize the intestine of the fish host and biofilm formation provides an adaptive and survival advantage for bacteria in an aquatic environment (Olsson et al 1996(Olsson et al , 1998. The major OMP may be useful as a component of a Vibrio vaccine and also for diagnostic purposes (Jung et al 2005, Hong et al 2009).…”