Saturday, February 16, 2013
Auditorium/Exhibit Hall C (Hynes Convention Center)
The genus Edwardsiella comprises a genetically distinct taxon related to other members of the Enterobacteriaceae family. It consists of bacteria differing strongly in their biochemical and physiological features, natural habitats, and pathogenic properties. Intrinsic resistance to the cyclic cationic antimicrobial peptides is a specific property of the genus Edwardsiella. Particularly E. ictaluri, an important pathogen of the catfish (Ictalurus punctatus) aquaculture and the causative agent of a fatal systemic infection, is highly resistant to cationic antimicrobial peptides (CAMPs). Previously, we determined that deletion of UDP-glucose dehydrogenase, a required enzyme for the synthesis of E. ictaluri lipopolysaccharide (LPS), strongly influences the resistance to CAMPs. Here we evaluated the influence of wabG, a gene that encodes for the UDP-glucoronic acid transferase, in the resistance to CAMPs and fish virulence. UDP-glucoronic acid transferase links the lipid A–outer core to the inner core–oligopolysaccharides. In general, mutants of wabG gene present a truncated LPS. E. ictaluri ΔwabG mutants showed a pleiotropic effect, influencing not only LPS synthesis, but also CAMPs resistance, growth and biofilm formation. E. ictaluri ΔwabG showed a similar phenotype than E. ictaluri Δugd, indicating that these genes are in the same biochemical pathway. E. ictaluri ΔwabG was attenuated in zebrafish indicating the important role of LPS during fish pathogenesis. Here we conclude that deletion of E. ictaluri wabG has a pleiotropic effect in E. ictaluri physiology influencing LPS synthesis, CAMPs resistance and fish virulence.