Effect of multiple mutations in tricarboxylic acid cycle and one-carbon metabolism pathways on Edwardsiella ictaluri pathogenesis

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• 作者：N. Dahal ; H. Abdelhamed ; J. Lu ; A. Karsi ; M.L. Lawrence
• 关键词：Edwardsiella ictaluri ; Ictalurus punctatus ; Channel catfish ; Vaccine ; Tricarboxylic acid cycle ; Glycine cleavage protein
• 刊名：Veterinary Microbiology
• 出版年：21 February, 2014
• 年：2014
• 卷：169
• 期：1-2
• 页码：107-112
• 全文大小：1123 K

文摘

Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC). We have shown recently that tricarboxylic acid cycle (TCA) and one-carbon (C1) metabolism are involved in E. ictaluri pathogenesis. However, the effect of multiple mutations in these pathways is unknown. Here, we report four novel E. ictaluri mutants carrying double gene mutations in TCA cycle (Ei螖mdh螖sdhC, Ei螖frdA螖sdhC), C1 metabolism (Ei螖glyA螖gcvP), and both TCA and C1 metabolism pathways (Ei螖gcvP螖sdhC). In-frame gene deletions were constructed by allelic exchange and mutants鈥?virulence and vaccine efficacy were evaluated using in vivo bioluminescence imaging (BLI) as well as end point mortality counts in catfish fingerlings. Results indicated that all the double gene mutants were attenuated compared to wild-type (wt) E. ictaluri. There was a 1.39-fold average reduction in bioluminescence, and hence bacterial numbers, from all the mutants except for Ei螖frdA螖sdhC at 144 h post-infection. Vaccination with mutants was very effective in protecting channel catfish against subsequent infection with virulent E. ictaluri 93-146 strain. In particular, immersion vaccination resulted in complete protection. Our results provide further evidence on the importance of TCA and C1 metabolism pathways in bacterial pathogenesis.