在澳大利亚针鼹蜱（同色瘤蜱）中检测到新型疏螺旋体物种。
Novel Borrelia species detected in echidna ticks, Bothriocroton concolor, in Australia.
作者信息
Loh Siew-May, Gofton Alexander W, Lo Nathan, Gillett Amber, Ryan Una M, Irwin Peter J, Oskam Charlotte L
机构信息
Vector and Water-Borne Pathogen Research Laboratory, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
School of Biological Sciences, The University of Sydney, Sydney, New South Wales, Australia.
出版信息
Parasit Vectors. 2016 Jun 14;9(1):339. doi: 10.1186/s13071-016-1627-x.
BACKGROUND
To date, little has been documented about microorganisms harboured within Australian native ticks or their pathogenic potential. Recently, a Borrelia sp. related to the Relapsing Fever (RF) group was identified in a single tick removed from a wild echidna (Tachyglossus aculeatus). The present study investigated the presence of Borrelia in 97 Bothriocroton concolor ticks parasitizing echidnas in Queensland, New South Wales, and Victoria, Australia, using nested PCR with Borrelia-specific primers targeting the 16S rRNA (16S) and flaB genes.
RESULTS
Borrelia-specific PCR assays confirmed the presence of a novel Borrelia sp. related to the RF and reptile-associated (REP) spirochaetes in 38 (39 %) B. concolor ticks. This novel Borrelia sp. was identified in 41 % of the B. concolor ticks in Queensland and New South Wales, but not in any ticks from Victoria. The resulting flaB sequences (407 bp) were 88 and 86 % similar to the flaB sequences from Borrelia turcica and Borrelia hermsii, respectively. Of the ticks confirmed as Borrelia-positive following the flaB assay, 28 were positive with the 16S assay. Phylogenetic analysis of the 16S sequences (1097 bp) suggests that these sequences belong to a novel Borrelia sp., which forms a unique monophyletic clade that is similar to, but distinct from, RF Borrelia spp. and REP-associated Borrelia spp.
CONCLUSIONS
We conclude that the novel Borrelia sp. identified in this study does not belong to the Borrelia burgdorferi (sensu lato) complex, and that the phylogenetic analysis of the partial 16S gene sequences suggests it forms a unique monophyletic cluster in the genus Borrelia, potentially forming a fourth major group in this genus associated with monotremes in Australia. However, a thorough molecular characterisation will be required to confirm the phylogenetic position of this unique Borrelia sp. The zoonotic potential and pathogenic consequences of this novel Borrelia sp. are unknown at the current time.
背景
迄今为止，关于澳大利亚本土蜱虫体内携带的微生物及其致病潜力的文献记载很少。最近，在一只从野生针鼹（短吻针鼹）身上采集的蜱虫中发现了一种与回归热（RF）菌群相关的疏螺旋体。本研究利用针对16S核糖体RNA（16S）和flaB基因的疏螺旋体特异性引物进行巢式聚合酶链反应（PCR），调查了寄生在澳大利亚昆士兰州、新南威尔士州和维多利亚州针鼹身上的97只康氏硬蜱中疏螺旋体的存在情况。
结果
疏螺旋体特异性PCR检测证实，在38只（39%）康氏硬蜱中存在一种与RF和爬行动物相关（REP）螺旋体有关的新型疏螺旋体。在昆士兰州和新南威尔士州41%的康氏硬蜱中发现了这种新型疏螺旋体，但在维多利亚州的蜱虫中未发现。所得的flaB序列（407 bp）分别与土耳其疏螺旋体和赫氏疏螺旋体的flaB序列有88%和86%的相似性。在flaB检测后被确认为疏螺旋体阳性的蜱虫中，有28只在16S检测中呈阳性。对16S序列（1097 bp）的系统发育分析表明，这些序列属于一种新型疏螺旋体，它形成了一个独特的单系分支，与RF疏螺旋体属和REP相关疏螺旋体属相似但不同。
结论
我们得出结论，本研究中鉴定出的新型疏螺旋体不属于伯氏疏螺旋体（广义）复合体，部分16S基因序列的系统发育分析表明，它在疏螺旋体属中形成了一个独特的单系簇，可能在该属中形成与澳大利亚单孔目动物相关的第四个主要类群。然而，需要进行全面的分子特征分析来确认这种独特疏螺旋体的系统发育位置。目前，这种新型疏螺旋体的人畜共患病潜力和致病后果尚不清楚。
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