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首页> 外文期刊>Frontiers in Microbiology >Differential Growth of Francisella tularensis, Which Alters Expression of Virulence Factors, Dominant Antigens, and Surface-Carbohydrate Synthases, Governs the Apparent Virulence of Ft SchuS4 to Immunized Animals
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Differential Growth of Francisella tularensis, Which Alters Expression of Virulence Factors, Dominant Antigens, and Surface-Carbohydrate Synthases, Governs the Apparent Virulence of Ft SchuS4 to Immunized Animals

机译：italic tularensis的差异生长会改变毒力因子，优势抗原和表面碳水化合物合酶的表达，从而控制免疫动物的italic Ft italic Sc​​huS4的毒力。

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The gram-negative bacterium Francisella tularensis ( Ft ) is both a potential biological weapon and a naturally occurring microbe that survives in arthropods, fresh water amoeba, and mammals with distinct phenotypes in various environments. Previously, we used a number of measurements to characterize Ft grown in Brain-Heart Infusion (BHI) broth as (1) more similar to infection-derived bacteria, and (2) slightly more virulent in na?ve animals, compared to Ft grown in Mueller Hinton Broth (MHB). In these studies we observed that the free amino acids in MHB repress expression of select Ft virulence factors by an unknown mechanism. Here, we tested the hypotheses that Ft grown in BHI (BHI- Ft ) accurately displays a full protein composition more similar to that reported for infection-derived Ft and that this similarity would make BHI- Ft more susceptible to pre-existing, vaccine-induced immunity than MHB- Ft . We performed comprehensive proteomic analysis of Ft grown in MHB, BHI, and BHI supplemented with casamino acids (BCA) and compared our findings to published “omics” data derived from Ft grown in vivo . Based on the abundance of ~1,000 proteins, the fingerprint of BHI- Ft is one of nutrient-deprived bacteria that—through induction of a stringent-starvation-like response—have induced the FevR regulon for expression of the bacterium's virulence factors, immuno-dominant antigens, and surface-carbohydrate synthases. To test the notion that increased abundance of dominant antigens expressed by BHI- Ft would render these bacteria more susceptible to pre-existing, vaccine-induced immunity, we employed a battery of LVS-vaccination and S4-challenge protocols using MHB- and BHI-grown Ft S4. Contrary to our hypothesis, these experiments reveal that LVS-immunization provides a barrier to infection that is significantly more effective against an MHB-S4 challenge than a BHI-S4 challenge. The differences in apparent virulence to immunized mice are profoundly greater than those observed with primary infection of na?ve mice. Our findings suggest that tularemia vaccination studies should be critically evaluated in regard to the growth conditions of the challenge agent.
机译：革兰氏阴性菌弗朗西斯菌（Ft）是一种潜在的生物武器，也是一种自然存在的微生物，它可以在节肢动物，淡水变形虫和具有不同表型的哺乳动物中生存。以前，我们使用多种测量方法来描述在脑心浸液（BHI）肉汤中生长的Ft与（1）与感染的细菌相比更相似，以及（2）在幼稚动物中比生长的Ft更具毒性位于Mueller Hinton Broth（MHB）。在这些研究中，我们观察到MHB中的游离氨基酸通过未知机制抑制了某些Ft毒力因子的表达。在这里，我们测试了BHI中生长的Ft（BHI- Ft）准确显示出与报道的感染性Ft更相似的完整蛋白质组成的假设，并且这种相似性将使BHI-Ft更易于感染已有的疫苗-诱导的免疫力比MHB-Ft高。我们对MHB，BHI和补充了酪蛋白氨基酸（BCA）的BHI中生长的Ft进行了全面的蛋白质组学分析，并将我们的发现与已发表的体内生长Ft的“组学”数据进行了比较。根据约1000种蛋白质的丰度，BHI-Ft的指纹图谱是营养缺乏的细菌之一，它通过诱导严格饥饿样反应而诱导了FevR调控因子表达细菌的毒力因子，显性抗原和表面碳水化合物合酶。为了测试BHI-Ft表达的优势抗原的丰度增加会使这些细菌更容易受到疫苗诱导的既存免疫的观念，我们采用了MVS和BHI-的LVS疫苗接种和S4攻击方案Ft S4。与我们的假设相反，这些实验表明，LVS免疫提供了一种感染屏障，与MHI-S4攻击相比，它对MHB-S4攻击的抵抗力明显更高。对免疫小鼠的表观毒力差异远远大于对初次感染的初次感染小鼠所观察到的差异。我们的发现表明，应针对挑战剂的生长条件严格评估图拉血疫苗的研究。

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