Fukunaga M, Takahashi Y, Tsuruta Y, Matsushita O, Ralph D, McClelland M, Nakao M
Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Hiroshima, Japan.
Int J Syst Bacteriol. 1995 Oct;45(4):804-10. doi: 10.1099/00207713-45-4-804.
The ixodid tick Ixodes persulcatus is the most important vector of Lyme disease in Japan. Most spirochete isolates obtained from I. persulcatus ticks have been classified as Borrelia burgdorferi sensu lato because of their genetic, biological, and immunological characteristics. However, we found that a small number of isolates obtained from I. persulcatus contained a smaller 38-kDa endoflagellar protein and single 23S-5S rRNA gene unit. Representative isolate HT31T (T = type strain) had the same 23S rRNA gene physical map as Borrelia turicatae. The DNA base composition of strain HT31T was 28.6 mol% G+C. DNA-DNA hybridization experiments revealed that strain HT31T exhibited moderate levels of DNA relatedness (24 to 51%) with Borrelia hermsii, B. turicatae, Borrelia parkeri, and Borrelia coriaceae. However, the levels of DNA reassociation with the previously described Lyme disease borreliae (B. burgdorferi, Borrelia garinii, and Borrelia afzelii) were only 8 to 13%. None of the previously described species examined exhibited a high level of DNA relatedness with strain HT31T. In addition, the 16S rRNA gene sequence (length, 1,368 nucleotides) of strain HT31T was determined and aligned with the 16S rRNA sequences of other Borrelia species. Distance matrix analyses were performed, and a phylogenetic tree was constructed. The results showed that isolate HT31T is only distantly related to both previously described Lyme disease borreliae and relapsing fever borreliae. Thus, the spirochetes isolated from I. persulcatus and closely related isolates should be classified as members of a new Borrelia species. We propose the name Borrelia miyamotoi sp. nov. for this spirochete; strain HT31 is the type strain.
全沟硬蜱是日本莱姆病最重要的传播媒介。从全沟硬蜱中分离出的大多数螺旋体菌株，由于其遗传、生物学和免疫学特征，已被归类为广义的伯氏疏螺旋体。然而，我们发现从全沟硬蜱中分离出的少数菌株含有较小的38-kDa内鞭毛蛋白和单个23S-5S rRNA基因单位。代表性菌株HT31T（T = 模式菌株）具有与图莱里疏螺旋体相同的23S rRNA基因物理图谱。菌株HT31T的DNA碱基组成为28.6 mol% G+C。DNA-DNA杂交实验表明，菌株HT31T与赫氏疏螺旋体、图莱里疏螺旋体、帕克疏螺旋体和科氏疏螺旋体表现出中等水平的DNA相关性（24%至51%）。然而，与先前描述的莱姆病疏螺旋体（伯氏疏螺旋体、伽氏疏螺旋体和阿氏疏螺旋体）的DNA重新结合水平仅为8%至13%。所检测的先前描述的物种中，没有一个与菌株HT31T表现出高度的DNA相关性。此外，测定了菌株HT31T的16S rRNA基因序列（长度为1368个核苷酸），并与其他疏螺旋体物种的16S rRNA序列进行比对。进行了距离矩阵分析，并构建了系统发育树。结果表明，分离株HT31T与先前描述的莱姆病疏螺旋体和回归热疏螺旋体都只有远缘关系。因此，从全沟硬蜱中分离出的螺旋体及密切相关的分离株应被归类为一个新的疏螺旋体物种的成员。我们提议将这种螺旋体命名为宫本疏螺旋体新种；菌株HT31为模式菌株。
