The High Diversity and Global Distribution of the Intracellular Bacterium Rickettsiella in the Polar Seabird Tick Ixodes uriae
The High Diversity and Global Distribution of the Intracellular Bacterium Rickettsiella in the Polar Seabird Tick Ixodes uriae
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DOI：
10.1007/s00248-015-0702-8
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发表时间：
2016-04-01
影响因子：
3.6
通讯作者：
McCoy, Karen D.
中科院分区：
文献类型：
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作者：
Duron, Olivier;Cremaschi, Julie;McCoy, Karen D.
专性细胞内细菌的立克次氏体属正在出现的广泛和生物多样性的节肢动物。一些立克次氏体菌株是高毒性昆虫病原体，而另一些则是母系遗传的内共生体，对宿主表型施加非常微妙的操纵以促进其自身的传播。最近，各种各样的立克次氏体菌株已被报道从蜱，但他们的生物学是完全未知的。在本研究中，我们研究了在11个不同地理种群的极地海鸟蜱硬蜱uriae立克次体的发病率和多样性。我们在大多数蜱虫种群中发现了立克次氏体，患病率为3%至24%。16S核糖体RNA（rRNA）和GroEL基因序列揭示了立克次氏体的一种意想不到的多样性，在I.尿。系统发育调查进一步揭示，这些立克次体菌株不集群内的蜱特异性分支，而是表现出不同的进化起源，表现出频繁的水平转移之间的远亲节肢动物物种。蜱饲养进一步表明，立克次氏体存在于受感染雌性所产的卵中，没有流产发育的证据。利用该数据集，我们讨论了立克次氏体在海鸟蜱中的潜在生物学意义。最值得注意的是，我们认为这些生物可能不是致病形式，而是使用更微妙的适应性策略在蜱虫种群中持续存在。
Obligate intracellular bacteria of the Rickettsiella genus are emerging as both widespread and biologically diverse in arthropods. Some Rickettsiella strains are highly virulent entomopathogenic agents, whereas others are maternally inherited endosymbionts exerting very subtle manipulations on host phenotype to promote their own spread. Recently, a variety of Rickettsiella strains have been reported from ticks, but their biology is entirely unknown. In the present study, we examined the incidence and diversity of Rickettsiella in 11 geographically distinct populations of the polar seabird tick Ixodes uriae. We found Rickettsiella in most tick populations with a prevalence ranging from 3 to 24 %. 16S ribosomal RNA (rRNA) and GroEL gene sequences revealed an unexpected diversity of Rickettsiella, with 12 genetically distinct Rickettsiella strains present in populations of I. uriae. Phylogenetic investigations further revealed that these Rickettsiella strains do not cluster within a tick-specific clade but rather exhibit distinct evolutionary origins demonstrating frequent horizontal transfers between distantly related arthropod species. Tick rearing further showed that Rickettsiella are present in eggs laid by infected females with no evidence of abortive development. Using this data set, we discuss the potential biological significance of Rickettsiella in seabird ticks. Most notably, we suggest that these organisms may not be pathogenic forms but rather use more subtle adaptive strategies to persist within tick populations.