Relapsing Fever Spirochetes Retain Infectivity After Prolonged in vitro Cultivation
Relapsing Fever Spirochetes Retain Infectivity After Prolonged in vitro Cultivation
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DOI：
10.1089/vbz.2008.0033
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发表时间：
2008-12-01
影响因子：
2.1
通讯作者：
Schwan, Tom G.
中科院分区：
文献类型：
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作者：
Lopez, Job E.;Schrumpf, Merry E.;Schwan, Tom G.
赫氏疏螺旋体（Borrelia hermsii）和伯氏疏螺旋体（Borrelin burgdorferi）是两种密切相关的螺旋体，分别是蜱传回归热和莱姆病的病原体。以前的研究表明B的传染性丧失。Burgdorferi与体外培养有关。这降低了B的传染性。早在三次体外传代时就发生了伯氏螺旋体感染，并且在这些毒性较低的培养物到非感染性培养物中观察到质粒的丢失。长期体外培养对B. hermsii没有被研究过。然而，了解螺旋体在体外培养过程中基因组降解的程度对于研究螺旋体的致病机制非常重要。本研究分析了连续体外培养对B的基因组组成和感染性的影响。hermsii和B. turiclavia。我们报告所有七个分离的B。hermsii和B.在体外连续培养1年后，检测了turiclavin在小鼠中的保留感染性。此外，长期培养后质粒谱几乎没有明显差异。两株B. hermsii在高传代后保持感染性，尽管丢失了含有编码因子H结合蛋白的fhbA基因的200-kb线性质粒的一部分。此外，多个B的序列分析。hermsii分离物显示两种类型的fhbA，与B的两个基因组完全一致。赫姆氏螺旋体因此，这些结果表明回归热螺旋体在体外培养过程中是遗传稳定的，并且在培养过程中丢失的含有fhbA的DNA片段不是感染所必需的。
Borrelia hermsii and Borrelin burgdorferi, two closely related spirochetes, are the etiological agents of tick-borne relapsing fever and Lyme disease, respectively. Previous studies have shown the loss of infectivity of B. burgdorferi is associated with in vitro cultivation. This diminished infectivity of B. burgdorferi has occurred as early as three in vitro passages, and the loss of plasmids have been observed with these less virulent to noninfective cultures. The effects of long-term in vitro cultivation on B. hermsii have not been investigated. However, understanding the degree of genomic degradation during in vitro cultivation is important for investigating pathogenic mechanisms of spirochetes. In this study, we analyzed the effects of continuous in vitro cultivation on the genomic composition and infectivity of B. hermsii and B. turicatae. We report that all seven isolates of B. hermsii and the one isolate Of B. turicatae examined retained infectivity in mice after 1 year of continuous in vitro cultivation. Furthermore, there were few apparent differences in the plasmid profiles after long-term cultivation. Two isolates of B. hermsii remained infective after high passage despite losing a portion of the 200-kb linear plasmid containing the fhbA gene encoding the factor H binding protein. Also, sequence analysis of multiple B. hermsii isolates demonstrated two types of fhbA with complete congruence with the two genomic groups of B. hermsii spirochetes. Therefore, these results suggest that relapsing fever spirochetes are genetically stable during in vitro cultivation, and the fhbA-containing segment of DNA that is lost during cultivation is not required for infection.