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首页> 外文期刊>Infection and immunity >Decreased Infectivity in Borrelia burgdorferi Strain B31 Is Associated with Loss of Linear Plasmid 25 or 28-1
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Decreased Infectivity in Borrelia burgdorferi Strain B31 Is Associated with Loss of Linear Plasmid 25 or 28-1

机译：伯氏疏螺旋体B31株的感染力降低与线性质粒25或28-1的丢失有关

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Previous reports indicated a correlation between loss of plasmids and decreased infectivity of Borrelia burgdorferi strain B31, suggesting that plasmids may encode proteins that are required for pathogenesis. In this study, we expand on this correlation. Using theB. burgdorferi genomic sequence, we designed primers specific for each plasmid, and by using PCR we catalogued 11 linear and 2 circular plasmids from 49 clonal isolates of a mid-passage B. burgdorferi strain B31, initially derived from infected mouse skin, and 20 clones obtained from mouse skin infected with a low-passage isolate of B. burgdorferi strain B31. Among the 69 clones analyzed, nine distinct genotypes were identified relative to wild-type B. burgdorferi strain B31. Among the nine clonal genotypes obtained, only the 9-kb circular plasmid (cp9), the 25-kb linear plasmid (lp25), and either the 28-kb linear plasmid 1 or 4 (lp28-1 and lp28-4, respectively) were missing, in different combinations. We compared the infectivity of the wild-type strain, containing all known B. burgdorferi plasmids, with those of single mutants lacking either lp28-1, lp28-4, or lp25 and a double mutant missing both cp9 and lp28-1. The infectivity data indicated thatB. burgdorferi strain B31 cells lacking lp28-4 were modestly attenuated in all tissues analyzed, whereas samples missing lp25 were completely attenuated in all tissues, even at the highest inoculum tested. Isolates without lp28-1 infected the joint tissue yet were not able to infect other tissues as effectively. In addition, we have observed a selection in vivo in the skin, bladder, and joint for cells containing lp25 and in the skin and bladder for cells containing lp28-1, indicating that lp25 and lp28-1 encode proteins required for colonization and short-term maintenance in these mammalian tissues. In contrast, there was no selection in the joint for cells containing lp28-1, suggesting that genes on lp28-1 are not required for colonization of B. burgdorferi within the joint. These observations imply that the dynamic nature of the B. burgdorferi genome may provide the genetic heterogeneity necessary for survival in the diverse milieus that this pathogen occupies in nature and may contribute to tropism in certain mammalian host tissues.
机译：先前的报道表明质粒的缺失与Borrelia burgdorferi B31菌株的感染力降低之间存在相关性，这表明质粒可能编码致病所需的蛋白质。在这项研究中，我们扩展了这种相关性。使用 B。 burgdorferi 基因组序列，我们设计了对每种质粒特异的引物，并通过PCR从中途传代的 B的49个克隆分离物中分类了11个线性和2个环状质粒。最初来自感染小鼠皮肤的burgdorferi B31菌株，以及从感染了 B低通道菌株的小鼠皮肤获得的20个克隆。 burgdorferi菌株B31。在分析的69个克隆中，相对于野生型 B鉴定出9个不同的基因型。 burgdorferi菌株B31。在获得的9种克隆基因型中，仅9 kb环状质粒（cp9），25 kb线性质粒（lp25）和28 kb线性质粒1或4（分别为lp28-1和lp28-4）丢失，以不同的组合。我们比较了包含所有已知 B的野生型菌株的感染性。 burgdorferi质粒，单个突变体缺少lp28-1，lp28-4或lp25，而双突变体则缺少cp9和lp28-1。传染性数据表明 B。缺少lp28-4的burgdorferi菌株B31细胞在所有分析的组织中均被适度减毒，而缺少lp25的样品在所有组织中均被完全减毒，即使在最高接种量下也是如此。没有lp28-1的分离株感染了关节组织，但不能同样有效地感染其他组织。此外，我们已经观察到体内对lp25和lp28-1细胞的选择是在皮肤，膀胱和关节中进行的，而对于lp28-1的细胞则在皮肤和膀胱中进行了选择，这表明lp25和lp28-1编码了定殖和短-这些哺乳动物组织中的长期维护。相反，对于含有lp28-1的细胞，在关节中没有选择，这表明lp28-1上的基因对于 B的定殖不是必需的。联合中的burgdorferi 。这些观察结果暗示了 B的动态性质。 burgdorferi基因组可能提供该病原体在自然环境中生存的多样化环境中必需的遗传异质性，并且可能在某些哺乳动物宿主组织中导致嗜性。

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