Surveillance of Lyme disease borreliae and vector ticks

我们从悉尼地区的澳大利亚莱姆病患者的皮肤标本中分离到一种螺旋体，并对其进行了鉴定.通过鞭毛蛋白和rDNA序列比较，该分离物与欧洲伽氏疏螺旋体亲缘关系较近。结果表明，莱姆病疏螺旋体也可能分布在澳大利亚。因此，我们调查了蜱在悉尼地区的分布和感染的疏螺旋体在澳大利亚蜱，硬蜱holocyclus。利用5.8S和28 SrRNA基因的ITS 2序列和线粒体rrs序列分析了硬蜱的系统关系。引起莱姆病的疏螺旋体螺旋体的蜱媒。我们在5%的蜱中肠组织中发现了螺旋体，但它们在BSKII培养基中不生长。使用16 S rDNA和/或鞭毛蛋白基因序列的已知引物组进行的PCR扩增对此类蜱中肠组织样品也无活性。ITS 2序列的系统发育分析表明，I. Horocyclus与其他与莱姆病相关的蜱种Borreliae相距甚远。以上结果表明：（1）澳大利亚蜱中存在未知种类的螺旋体;全环虫（2）它们似乎与媒介蜱虫物种有特定的联系（3）目前还不知道它会传播导致人类莱姆病的疏螺旋体。疏螺旋体分类群的系统发育和氧化物蜱类之间的系统发育关系具有高度的一致性，这表明蜱-螺旋体组合中存在共同物种形成的历史。结果表明，在澳大利亚疏螺旋体的发生和分布取决于特定蜱种的媒介能力。

We have isolated and characterizedspirochete from skin sample of Australian Lyme disease patient in Sydney area. The isolate was closely related with European Borrelia garinii by comparing its flagellin and rDNA sequences. The outcome indicated that Lyme disease borreliae may also distributed in Australia. We, therefore, investigated tick distribution in Sydney area and infestation of borreliae in Australian tick, Ixodes holocyclus. An internal transcribed spacer (ITS2) sequence between the 5.8S and 28S rRNA genes and mitochondrial rrs sequence were used to estimate the phyletic relationship among Lxodes spp. Tick vectors of Lyme disease-causing Borrelia spirochetes. We found spirochetes in 5% of the tick-mid-gut tissues examined but they did not grow in BSKII medium. PCR amplification using known primer sets for 16S rDNA and/or flagellin gene sequence was also inactive against such tick mid-gut tissue samples. Phyletic analysis by ITS2 sequence indicated that I. Horocyclus is far from the other tick species associated with Lyme disease borreliae. All of out results indicate (1) unknown species of spirochetes is infest in Australian ticks, I. Holocyclus (2) they appear to have a specific association with vector tick species (3) it is not known to transmit the Borrelia-that cause Lyme disease in humans. There is a high degree of concordance in the phylogenetic of Borrelia taxa and the phylogenetic relationships among Oxides ticks, which suggests a history of cospeciation in the tick-spirochete assemblage. The results suggest that the occurrence and distribution of Borrelia in Australia are depend on the vector competence of particular tick species.