Meriläinen Leena, Herranen Anni, Schwarzbach Armin, Gilbert Leona
Department of Biological and Environmental Sciences and NanoScience Center, University of Jyväskylä, Jyväskylä, Finland
Department of Biological and Environmental Sciences and NanoScience Center, University of Jyväskylä, Jyväskylä, Finland.
Microbiology (Reading). 2015 Mar;161(Pt 3):516-27. doi: 10.1099/mic.0.000027. Epub 2015 Jan 6.
The spirochaete bacterium Borrelia burgdorferi sensu lato is the causative agent of Lyme disease, the most common tick-borne infection in the northern hemisphere. There is a long-standing debate regarding the role of pleomorphic forms in Lyme disease pathogenesis, while very little is known about the characteristics of these morphological variants. Here, we present a comprehensive analysis of B. burgdorferi pleomorphic formation in different culturing conditions at physiological temperature. Interestingly, human serum induced the bacterium to change its morphology to round bodies (RBs). In addition, biofilm-like colonies in suspension were found to be part of B. burgdorferi's normal in vitro growth. Further studies provided evidence that spherical RBs had an intact and flexible cell envelope, demonstrating that they are not cell wall deficient, or degenerative as previously implied. However, the RBs displayed lower metabolic activity compared with spirochaetes. Furthermore, our results indicated that the different pleomorphic variants were distinguishable by having unique biochemical signatures. Consequently, pleomorphic B. burgdorferi should be taken into consideration as being clinically relevant and influence the development of novel diagnostics and treatment protocols.
疏螺旋体伯氏疏螺旋体复合群是莱姆病的病原体，莱姆病是北半球最常见的蜱传感染疾病。关于多形性形式在莱姆病发病机制中的作用存在长期争论，而对于这些形态变体的特征却知之甚少。在此，我们对生理温度下不同培养条件下伯氏疏螺旋体的多形性形成进行了全面分析。有趣的是，人血清诱导该细菌将其形态转变为圆体（RBs）。此外，悬浮状态下类似生物膜的菌落被发现是伯氏疏螺旋体正常体外生长的一部分。进一步的研究提供了证据，表明球形RBs具有完整且灵活的细胞膜，证明它们并非如先前所暗示的那样缺乏细胞壁或发生退化。然而，与螺旋体相比，RBs显示出较低的代谢活性。此外，我们的结果表明，不同的多形性变体具有独特的生化特征，从而可以区分。因此，多形性伯氏疏螺旋体在临床上应被视为具有相关性，并会影响新型诊断和治疗方案的开发。
