Omsland Anders, Cockrell Diane C, Howe Dale, Fischer Elizabeth R, Virtaneva Kimmo, Sturdevant Daniel E, Porcella Stephen F, Heinzen Robert A
Coxiella Pathogenesis Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
Proc Natl Acad Sci U S A. 2009 Mar 17;106(11):4430-4. doi: 10.1073/pnas.0812074106. Epub 2009 Feb 25.
The inability to propagate obligate intracellular pathogens under axenic (host cell-free) culture conditions imposes severe experimental constraints that have negatively impacted progress in understanding pathogen virulence and disease mechanisms. Coxiella burnetii, the causative agent of human Q (Query) fever, is an obligate intracellular bacterial pathogen that replicates exclusively in an acidified, lysosome-like vacuole. To define conditions that support C. burnetii growth, we systematically evaluated the organism's metabolic requirements using expression microarrays, genomic reconstruction, and metabolite typing. This led to development of a complex nutrient medium that supported substantial growth (approximately 3 log(10)) of C. burnetii in a 2.5% oxygen environment. Importantly, axenically grown C. burnetii were highly infectious for Vero cells and exhibited developmental forms characteristic of in vivo grown organisms. Axenic cultivation of C. burnetii will facilitate studies of the organism's pathogenesis and genetics and aid development of Q fever preventatives such as an effective subunit vaccine. Furthermore, the systematic approach used here may be broadly applicable to development of axenic media that support growth of other medically important obligate intracellular pathogens.
无法在无菌（无宿主细胞）培养条件下繁殖专性细胞内病原体，这带来了严重的实验限制，对理解病原体毒力和疾病机制方面的进展产生了负面影响。人类Q热的病原体伯纳特立克次体是一种专性细胞内细菌病原体，仅在酸化的、类似溶酶体的液泡中复制。为了确定支持伯纳特立克次体生长的条件，我们使用表达微阵列、基因组重建和代谢物分型系统地评估了该生物体的代谢需求。这导致开发出一种复杂的营养培养基，在2.5%的氧气环境中能支持伯纳特立克次体大量生长（约3个对数级（10））。重要的是，无菌培养的伯纳特立克次体对Vero细胞具有高度传染性，并表现出体内生长生物体的发育形态。伯纳特立克次体的无菌培养将有助于对该生物体的发病机制和遗传学进行研究，并有助于开发Q热预防措施，如有效的亚单位疫苗。此外，这里使用的系统方法可能广泛适用于开发支持其他医学上重要的专性细胞内病原体生长的无菌培养基。
