Sequence typing reveals extensive strain diversity of the Lyme borreliosis agents Borrelia burgdorferi in North America and Borrelia afzelii in Europe
Sequence typing reveals extensive strain diversity of the Lyme borreliosis agents Borrelia burgdorferi in North America and Borrelia afzelii in Europe
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DOI：
10.1099/mic.0.26944-0
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发表时间：
2004-06-01
期刊：
影响因子：
2.8
通讯作者：
Barbour, AG
中科院分区：
文献类型：
--
作者：
Bunikis, J;Garpmo, U;Barbour, AG
本文通过对莱姆病的两个病原体--伯氏疏螺旋体和阿氏疏螺旋体染色体上的rrs-rrlA基因间区（IGS）和外膜蛋白基因p66以及质粒上的外膜蛋白基因ospA和ospC进行序列分型，研究了两个病原体的遗传多态性。用于PCR扩增和测序的DNA的主要来源是B的样品。burgdorferi蜱媒介Ixodes scapularis，在美国东北部流行地区的现场收集，和B。afzelii载体篦麻硬蜱，收集在瑞典南部的类似地点。将序列与参考菌株和皮肤活检分离株的序列以及数据库序列进行比较。为了B。burgdorferi的4个基因座各有10-13个等位基因，共发现9个连锁的无性系。在afzelii中检测到2个基因座ospC和IGS，共鉴定出11种IGS基因型，12个ospC等位基因和9个连锁群。B的遗传变异。burgdorferi和B. afzelii的样品中，从现场网站占了大部分的遗传多样性，以前报告的更大的地区，美国东北部和中欧和北方欧洲。虽然这两个物种的ospC等位基因具有较高的核苷酸多样性比其他位点，ospC位点显示基因内重组的证据，是不适合的系统发育推断。相反，在B的IGS基因座处没有检测到重组。burgdorferi。此外，除了指定10种IGS基因型的签名核苷酸外，还有额外的核粒多态性，共定义了24种亚型。B的最大似然和简约分支图。burgdorferi比对的IGS序列显示亚型序列是进化枝的末端分支，并且在B内存在至少三个单系谱系。burgdorferi。结果表明，B. burgdorferi和B. afzelii有更大的遗传多样性比以前估计的，和IGS基因座单独是足够的菌株分型和系统发育研究。
The genetic polymorphism of Borrelia burgdorferi and Borrelia afzelii, two species that cause Lyme borreliosis, was estimated by sequence typing of four loci: the rrs-rrlA intergenic spacer (IGS) and the outer-membrane-protein gene p66 on the chromosome, and the outer-membrane-protein genes ospA and ospC on plasmids. The major sources of DNA for PCR amplification and sequencing were samples of the B. burgdorferi tick vector Ixodes scapularis, collected at a field site in an endemic region of the north-eastern United States, and the B. afzelii vector Ixodes ricinus, collected at a similar site in southern Sweden. The sequences were compared with those of reference strains and skin biopsy isolates, as well as database sequences. For B. burgdorferi, 10-13 alleles for each of the 4 loci, and a total of 9 distinct clonal lineages with linkage of all 4 loci, were found. For B. afzelii, 2 loci, ospC and IGS, were examined, and 11 IGS genotypes, 12 ospC alleles, and a total of 9 linkage groups were identified. The genetic variants of B. burgdorferi and B. afzelii among samples from the field sites accounted for the greater part of the genetic diversity previously reported from larger areas of the north-eastern United States and central and northern Europe. Although ospC alleles of both species had higher nucleotide diversity than other loci, the ospC locus showed evidence of intragenic recombination and was unsuitable for phylogenetic inference. In contrast, there was no detectable recombination at the IGS locus of B. burgdorferi. Moreover, beyond the signature nucleotides that specified 10 IGS genotypes, there were additional nucleoticle polymorphisms that defined a total of 24 subtypes. Maximum-likelihood and parsimony cladograms of B. burgdorferi aligned IGS sequences revealed the subtype sequences to be terminal branches of clades, and the existence of at least three monophyletic lineages within B. burgdorferi. It is concluded that B. burgdorferi and B. afzelii have greater genetic diversity than had previously been estimated, and that the IGS locus alone is sufficient for strain typing and phylogenetic studies.