Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii.
Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii.
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DOI：
10.1186/1471-2180-12-232
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发表时间：
2012-10-11
期刊：
影响因子：
4.2
通讯作者：
Creuzenet C
中科院分区：
文献类型：
--
作者：
Bui XT;Qvortrup K;Wolff A;Bang DD;Creuzenet C
空肠弯曲菌是欧洲和北美细菌性食源性疾病的主要原因。允许在环境中生存和传播到新宿主的机制尚不清楚。环境中自由生活的原生动物可能促进这两个过程。预先暴露于环境中遇到的热、饥饿、氧化或渗透胁迫可能会影响C.空肠内有自由生活的原生动物。为了验证这一假设，我们研究了环境胁迫对C.空肠和其摄取和细胞内存活的卡氏阿米巴。高温、饥饿和渗透胁迫降低了C.空肠显着，而氧化应激没有影响。定量RT-PCR实验表明，在高温和氧化胁迫下，毒力基因的转录水平略有上调，而在饥饿和渗透胁迫下，毒力基因的转录水平下调，其中htrA基因在渗透胁迫下的下调幅度最大。预先暴露的细菌低营养或渗透压应力减少细菌吸收阿米巴，但没有观察到热或氧化应激的影响。最后，C.空肠在变形虫细胞内迅速丧失活力，并且预先暴露于氧化应激对细胞内存活没有显著影响。然而，庆大霉素处理后5小时恢复的细胞内细菌的数量与饥饿，热处理或热应激的细菌比对照细菌低。此外，虽然用对照细菌进行庆大霉素处理后24 h通常可回收约1.5 × 103菌落形成单位/ml内化细菌，但在该时间点不能回收饥饿、热处理或饥饿应激细菌。总的来说，C.空肠对环境胁迫的反应并不能促进A. castellanii。总之，这些发现表明，C。jejuni及其与A. castellanii是复杂的和多因素的，但预先暴露于各种压力并不启动C。jejuni的存活率。castellanii。
Campylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure to heat, starvation, oxidative or osmotic stresses encountered in the environment may affect the subsequent interaction of C. jejuni with free-living protozoa. To test this hypothesis, we examined the impact of environmental stress on expression of virulence-associated genes (ciaB, dnaJ, and htrA) of C. jejuni and on its uptake by and intracellular survival within Acanthamoeba castellanii. Heat, starvation and osmotic stress reduced the survival of C. jejuni significantly, whereas oxidative stress had no effect. Quantitative RT-PCR experiments showed that the transcription of virulence genes was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the htrA gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect of heat or oxidative stress was observed. Finally, C. jejuni rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved, heat treated or osmotically stressed bacteria than with control bacteria. Also, while ~1.5 × 103 colony forming unit/ml internalized bacteria could typically be recovered 24 h post-gentamicin treatment with control bacteria, no starved, heat treated or osmotically stressed bacteria could be recovered at this time point. Overall, pre-exposure of C. jejuni to environmental stresses did not promote intracellular survival in A. castellanii. Together, these findings suggest that the stress response in C. jejuni and its interaction with A. castellanii are complex and multifactorial, but that pre-exposure to various stresses does not prime C. jejuni for survival within A. castellanii.
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