Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8750020 | Microbial Pathogenesis | 2016 | 27 Pages |
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia in fish, particularly in channel catfish. Ferric iron is an essential micronutrient for bacterial survival, and some bacterial pathogens use secreted hydroxamate-type siderophores to chelate iron in host tissues. Siderophore-iron complexes are taken up by these bacteria via the ferric hydroxamate uptake (Fhu) system. In E. ictaluri, the Fhu system consists of fhuC, fhuD, fhuB, and fhuA genes. However, the importance of the Fhu system in E. ictaluri virulence has not been investigated completely. Here, we present construction of E. ictaluri fhuD and fhuB mutants (EiÎfhuD and EiÎfhuB) by in-frame gene deletion and evaluation of the mutants' virulence and immunogenicity in channel catfish fingerlings and fry. Immersion challenges showed that EiÎfhuD was not significantly attenuated (p < 0.05) in catfish fingerlings, whereas EiÎfhuB was significantly attenuated (p < 0.01). Catfish fingerlings immunized with EiÎfhuD and EiÎfhuB showed 100% and 97.62% survival, respectively. Fry immersion challenges indicated EiÎfhuB was also significantly attenuated (p < 0.05) in two-week old fry compared to the wild-type (48.96% vs. 82.14% mortalities). The survival rate in the fry vaccinated with EiÎfhuB was significantly higher (p < 0.05) than that of non-vaccinated fry (96.77% vs. 21.42% survival). Our data indicates that the fhuB gene, but not the fhuD gene, contributes to E. ictaluri virulence.
Keywords
Related Topics
Life Sciences
Immunology and Microbiology
Microbiology
Authors
Hossam Abdelhamed, Jingjun Lu, Mark L. Lawrence, Attila Karsi,