Acronym Infectionbiology
Category
Aquaculture
Title Interactions between microorganisms and plants or animals Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National Coordinator Debra Milton Coordinator email debra.milton@molbiol.umu.se
Coordinator institution
UMU - UMEA University (Sweden)
Institutions involved
NA
Start year 2004 End year 2005 Funding (€) € 4,370 Website NA Summary Bacteria, once thought to be primitive single-celled organisms that function independently of other members of their species, are now known to have complex communication networks that allow coordination of activities as a population instead of as single cells. A unified action is advantageous for survival of the bacteria, as they often alter their morphology and physiology quickly to adapt to environmental changes that may be very harsh. The communication network that signals activities in accordance with the population density is called quorum sensing. Quorum sensing (QS) is now known to regulate diverse physiological activities, including production of virulence determinants, biofilm formation and colonization of the eukaryotic host. Thus, methods that disrupt or manipulate the quorum sensing signalling may be promising strategies for disease control. Vibrio anguillarum constitutes part of the normal microflora of the aquatic environment. During the summer months, V. anguillarum causes a haemorrhagic septicaemia in marine fish resulting in severe economical loss in fish production via the fish-farming industry. Successful vaccines are developed, however, they are limited to certain fish species and to the age of the fish. Thus, alternative therapeutic agents need to be developed, based on an understanding of the virulence mechanism and ecology of the fish pathogen. This work has led to novel findings showing that the V. anguillarum quorum sensing regulatory cascade is different to that of Vibrio harveyi and Vibrio fischeri. The functional analysis of this cascade has revealed a novel outer membrane protein required for resistance to the bactericidal effects of bile in the fish intestines and this protein is likely expressed only in the fish making the regulation of this gene an interesting target for drug discovery. Also regulated by QS is a new genetic locus involved in exopolysaccharide transport/biosynthesis that is required for biofilm formation on the outer surface epithelial cells of the fish scales and for entry of the bacterium into the fish from the seawater suggesting that V. anguillarum presides on the surface of the fish in a biofilm community protected from the innate immunity of the host. Moreover, within this new locus, a protein tyrosine kinase and phosphatase were identified and preliminary results show that these two proteins activate and inactivate proteins essential for virulence. Thus far, this is not a common means of regulating genes in prokaryotes and is a very exciting area for gene regulation and control for bacterial pathogens.
Goals:
(1) To better understand the molecular mechanism of virulence for Vibrio anguillarum; (2) To analyse the role of biofilm formation on the emergence of Vibrio anguillarum in the aquatic environment and in the fish host; (3) To characterize the mechanism of cell-cell signalling in V. anguillarum via acylhomoserine lactones (AHLs) and to determine what bacterial activities are regulated by these signal molecules.
Keywords
Fish;
Fish health;
Bacteria;
Disease;
Parasite;
Biology;
Genetic;
Marine Region
76
Not associated to marine areas
0
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