Establishing bacterial infectivity models in striped Catfish Pangasianodon hypophthalmus (Sauvage) with Edwardsiella ictaluri |
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Authors: | Nguyen Ngoc Phuoc Randolph Richards Margaret Crumlish |
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Institution: | 1. University of Agriculture and Forestry, Hue University, Hue, Vietnam;2. Institute of Aquaculture, University of Stirling, Stirling, UK |
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Abstract: | A bacterial infectivity challenge model of Edwardsiella ictaluri in striped catfish was developed. All experiments were conducted using a bacterial isolate of E. ictaluri that had been recovered during a natural outbreak of bacillary necrosis of Pangasianodon (BNP) in farmed striped catfish Pangasianodon hypophthalmus in Vietnam. Time of immersion in 107 CFU.ml?1 had a significant effect on mortality. The immersion bacterial dose of 107 CFU/ml for 30 s resulted in a cumulative percentage mortality of 63%. Three to four days post-bacterial challenge, fish showed gross clinical signs of natural BNP and E. ictaluri was recovered and identified from these fish. Moreover, a cohabitation challenge was evaluated as an alternative challenge method, although the mortalities among the infected fish were lower at around 15%–40%. This study confirmed the horizontal transmission of E. ictaluri in striped catfish and elucidated that cohabitation challenge could be used in reproducing the disease under controlled conditions. |
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Keywords: | bacillary necrosis of Pangasianodon cohabitation challenge Edwardsiella ictaluri immersion challenge Pangasianodon hypophthalmus |
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