NF Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russia.
Vector Borne Zoonotic Dis. 2010 Jun;10(5):453-8. doi: 10.1089/vbz.2009.0033.
The tick Ixodes pavlovskyi is taxonomically, morphologically, and ecologically close to the taiga tick Ixodes persulcatus, a major host and vector of Borrelia spirochetes. The recent range of I. pavlovskyi is disjoined into the Western Siberian and Far Eastern parts, with this tick being almost always sympatric with I. persulcatus. A total of 56 unfed adult I. pavlovskyi ticks from the biotope where this species was absolutely dominant (within the city limits of Tomsk, Western Siberia) and 50 I. persulcatus ticks from the vicinity of this city, where I. pavlovskyi was almost absent, were collected by flagging in May-June 2006, at the seasonal peak of their abundance. The guts and internal organs of individual ticks were inoculated into the Barbour-Stoenner-Kelly (BSK) medium. Thus, 35 Borrelia isolates were obtained and identified by means of polymerase chain reaction-restriction fragment length polymorphism analysis and sequencing of the rrfA-rrlB spacer and, selectively, an rrs gene fragment. The Borrelia infection rate in I. pavlovskyi (35.7 +/- 12.8%) was almost the same as in I. persulcatus (30.0 +/- 13.0%). Such a high infection rate in I. pavlovskyi shows that this vector can itself maintain natural foci of borreliosis, regardless of very low abundance or even absence of I. persulcatus. In both foci compared, Borrelia garinii prevailed in ixodid ticks (31 isolates). Three B. afzelii VS461 isolates were obtained from I. pavlovskyi. Therefore, independently of whether I. pavlovskyi or I. persulcatus is the main vector, B. garinii of two genomic groups, 20047 and NT29, can circulate in a natural focus, but B. garinii NT29 is more closely associated with I. persulcatus. Moreover, two isolates (one from I. pavlovskyi and one from I. persulcatus) proved to be completely identical to B. garinii ChY13p from I. persulcatus collected in China. The hypothesis is that these and other similar isolates described previously comprise an individual genomic group of B. garinii.
帕夫洛夫斯基硬蜱在分类学、形态学和生态学上与针叶林硬蜱 Ixodes persulcatus 密切相关，后者是螺旋体伯氏疏螺旋体的主要宿主和传播媒介。最近，帕夫洛夫斯基硬蜱的分布范围被分割成西西伯利亚和远东地区，而且这种蜱类几乎总是与 I. persulcatus 共存。总共从生物群落中收集了 56 只未进食的成年帕夫洛夫斯基硬蜱，这些蜱类在该物种绝对占主导地位的地方（在西伯利亚西部的托木斯克市范围内），以及 50 只来自该市附近的 I. persulcatus 蜱类，那里几乎没有帕夫洛夫斯基硬蜱。这些蜱类是在 2006 年 5 月至 6 月的丰水期通过标记法采集的。从个体蜱的肠道和内脏器官中接种到 Barbour-Stoenner-Kelly (BSK) 培养基中。因此，通过聚合酶链反应-限制性片段长度多态性分析以及 rrfA-rrlB 间隔区和选择性 rrs 基因片段的测序，获得了 35 株伯氏疏螺旋体分离株并进行了鉴定。帕夫洛夫斯基硬蜱（35.7%±12.8%）的伯氏疏螺旋体感染率几乎与 I. persulcatus（30.0%±13.0%）相同。帕夫洛夫斯基硬蜱如此高的感染率表明，这种媒介本身可以维持自然的疏螺旋体病疫区，而不管 I. persulcatus 的丰度非常低甚至不存在。在比较的两个疫源地中，伯氏疏螺旋体加氏亚种在硬蜱中占优势（31 株）。从帕夫洛夫斯基硬蜱中获得了 3 株伯氏疏螺旋体 VS461 分离株。因此，无论帕夫洛夫斯基硬蜱还是 I. persulcatus 是主要媒介，两个基因组组 20047 和 NT29 的伯氏疏螺旋体都可以在自然疫源地中循环，但伯氏疏螺旋体 NT29 与 I. persulcatus 的关联更为密切。此外，两种分离株（一种来自帕夫洛夫斯基硬蜱，一种来自 I. persulcatus）与从中国采集的 I. persulcatus 中分离的伯氏疏螺旋体 ChY13p 完全相同。假设这些以及以前描述的其他类似分离株构成了伯氏疏螺旋体的一个单独的基因组组。
