Coxiella Pathogenesis Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
Annu Rev Microbiol. 2011;65:111-28. doi: 10.1146/annurev-micro-090110-102927.
For over seven decades, Coxiella burnetii, the causative agent of human Q fever, has been considered a prototypical obligate intracellular bacterium that relies exclusively on a eukaryotic cell for growth. Intracellularly, the organism prospers in an acidified, phagolysosome-like vacuole. C. burnetii has evolved to replicate in this harsh compartment by a mechanism involving acid activation of metabolism. The ?2 Mb genome of C. burnetii is about twice the size of genomes of most obligate intracellular bacteria, and the organism's central metabolic pathways are largely intact. The absence of extensive genome reduction suggests the adaptation of C. burnetii to an obligate intracellular lifestyle is a recent evolutionary event. Indeed, insight from early work on C. burnetii metabolism, along with new information gained from metabolic pathway reconstructions, nutrient typing, and expression profiling, allowed the rescue of C. burnetii from its host cell to regain the axenic growth capacity of its ancestors. This advance removes the extensive experimental obstacles associated with intracellular obligatism and opens the door for a renaissance in C. burnetii research.
七十多年来，柯克斯体（Q 热的病原体）一直被认为是一种典型的专性细胞内细菌，其生长完全依赖真核细胞。在细胞内，该生物在酸化的、类似吞噬体的空泡中茁壮成长。柯克斯体通过一种涉及代谢的酸激活机制在这种恶劣的环境中进行复制。约氏立克次体的?2 Mb 基因组大约是大多数专性细胞内细菌基因组的两倍，其中心代谢途径基本完整。基因组没有广泛减少表明，柯克斯体适应专性细胞内生活方式是最近的进化事件。事实上，早期关于柯克斯体代谢的工作所提供的见解，以及从代谢途径重建、营养类型和表达谱获得的新信息，使得能够从宿主细胞中拯救出柯克斯体，恢复其祖先的无菌生长能力。这一进展消除了与细胞内专性相关的广泛实验障碍，并为柯克斯体研究的复兴打开了大门。
