Isocitrate lyase activity is required for virulence of the intracellular pathogen Rhodococcus equi
Isocitrate lyase activity is required for virulence of the intracellular pathogen Rhodococcus equi
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DOI：
10.1128/iai.73.10.6736-6741.2005
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发表时间：
2005-10-01
影响因子：
3.1
通讯作者：
Meijer, WG
中科院分区：
文献类型：
--
作者：
Wall, DM;Duffy, PS;Meijer, WG
马红球菌是马驹的重要病原菌，可引起严重的化脓性肉芽肿性肺炎。维尤恩特河马属菌株在巨噬细胞内生长，这是一个特征仍然很差的过程。巨噬细胞内R. Equi是膜脂质衍生的脂肪酸，其在β氧化后通过乙醛酸旁路被同化。评估异柠檬酸裂合酶（乙醛酸旁路的第一种酶）在R.马的一个突变体，通过单一同源重组策略，使用自杀质粒含有R.马aceA基因编码异柠檬酸裂解酶。用aceA互补所得到的突变体表明突变体对该基因具有特异性。在小鼠巨噬细胞系中的毒力评估显示，与亲本菌株相比，突变体被杀死。对静脉感染小鼠肝脏的研究表明，突变体的清除率提高。当四个3周龄的马驹感染内支气管，aceA突变体是完全减毒，与亲本菌株。因此，aceA基因是决定R. equi，表明膜脂可能是被吞噬的R.等。
Rhodococcus equi is an important pathogen of foals, causing severe pyogranulomatous pneumonia. Virulent R. equi strains grow within macrophages, a process which remains poorly characterized. A potential source of carbon for intramacrophage R. equi is membrane lipid-derived fatty acids, which following beta oxidation are assimilated via the glyoxylate bypass. To assess the importance of isocitrate lyase, the first enzyme of the glyoxylate bypass, in virulence of a foal isolate of R. equi, a mutant was constructed by a strategy of single homologous recombination using a suicide plasmid containing an internal fragment of the R. equi aceA gene encoding isocitrate lyase. Complementation of the resulting mutant with aceA showed that the mutant was specific for this gene. Assessment of virulence in a mouse macrophage cell line showed that the mutant was killed, in contrast to the parent strain. Studies in the liver of intravenously infected mice showed enhanced clearance of the mutant. When four 3-week-old foals were infected intrabronchially, the aceA mutant was completely attenuated, in contrast to the parent strain. In conclusion, the aceA gene was shown to be essential for virulence of R. equi, suggesting that membrane lipids may be an important source of carbon for phagocytosed R. equi.