Neutral-red reaction is related to virulence and cell wall methyl-branched lipids in Mycobacterium tuberculosis
Neutral-red reaction is related to virulence and cell wall methyl-branched lipids in Mycobacterium tuberculosis
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DOI：
10.1016/j.micinf.2005.06.011
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发表时间：
2006-01-01
影响因子：
5.8
通讯作者：
Luquin, M
中科院分区：
文献类型：
--
作者：
Cardona, PJ;Soto, CY;Luquin, M
为了寻找结核分枝杆菌的毒力标记试验，杜博斯和米德尔布鲁克在1948年报告说，在中性红色的碱性水溶液中，毒力强的H37Rv结核分枝杆菌菌株的细胞固定了染料并变成了红色，而无毒的H37Ra结核分枝杆菌菌株的细胞却没有染色。在20世纪50年代和60年代，对新鲜分离的结核分枝杆菌进行了中性红细胞化学反应测试，据报道，它们呈中性红阳性，而其他不同环境来源的分枝杆菌对豚鼠无致病性，呈中性红阴性。然而，中性红色并没有真正被证明是一个毒力标记。为了测试毒性是否与中性红有关，我们研究了结核分枝杆菌的临床分离株，该株最初为中性红阳性，但在培养基中经过一年多后，变为中性红阴性。我们发现，与原始的中性红阳性菌株相比，这种中性红阴性变体在两种实验性结核病小鼠模型中被减弱。脂质分析表明，这种中性红色阴性自然突变体失去了合成硫代酚二真菌酸酯的能力，这是一种细胞壁甲基支链脂质，与结核分枝杆菌的毒力有关。我们还研究了不同基因靶向结核分枝杆菌突变体的中性红色，这些突变体不能产生硫代酚二真菌酸酯或其他细胞壁甲基支链脂质，如亚脂质和聚酰基海藻糖。我们发现在缺乏一种以上甲基支化脂质的突变体中存在负中性红反应。我们得出结论，中性红色确实是毒力的标志，它表明结核分枝杆菌细胞外表面的重要扰动。(c) 2005 Elsevier SAS。版权所有。
Searching for virulence marking tests for Mycobacteritan tuberculosis, Dubos and Middlebrook reported in 1948 that in an alkaline aqueous solution of neutral-red, the cells of the virulent H37Rv M. tuberculosis strain fixed the dye and became red in color, whereas the cells of the avirulent H37Ra M. tuberculosis strain remained unstained. In the 1950 and 1960s, fresh isolates of M. tuberculosis were tested for this neutral-red cytochemical reaction and it was reported that they were neutral-red positive, whereas other mycobacteria of diverse environmental origins that were non-pathogenic for guinea pigs were neutral-red negative. However, neutral-red has not really been proven to be a virulence marker. To test if virulence is in fact correlated to neutral-red, we studied a clinical isolate of M. tuberculosis that was originally neutral-red positive but, after more than I year passing through culture mediums, turned neutral-red negative. We found that, in comparison to the original neutral-red positive strain, this neutral-red negative variant was attenuated in two murine models of experimental tuberculosis. Lipid analysis showed that this neutral-red negative natural mutant lost the capacity to synthesize pthiocerol dimycocerosates, a cell wall methyl-branched lipid that has been related to virulence in M. tuberculosis. We also studied the neutral-red of different gene-targeted M. tuberculosis mutants unable to produce pthiocerol dimycocerosates or other cell wall methyl-branched lipids such as sulfolipids, and polyacyltrehaloses. We found a negative neutral-red reaction in mutants that were deficient in more than one type of methyl-branched lipids. We conclude that neutral-red is indeed a marker of virulence and it indicates important perturbations in the external surface of M. tuberculosis cells. (c) 2005 Elsevier SAS. All rights reserved.