MIVEGEC, UMR 5290 CNRS-IRD-UM1-um2, Centre IRD, 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France.
Infect Genet Evol. 2011 Dec;11(8):2043-8. doi: 10.1016/j.meegid.2011.09.016. Epub 2011 Sep 29.
Ixodes ricinus is a European tick that transmits numerous pathogenic agents, including the bacteria that cause Lyme disease (some genospecies of Borrelia burgdorferi sensu lato complex). This tick has been considered as a classic example of an extreme generalist vector. However, host-associations in such vector species are difficult to determine from field observations alone and recent work suggests that host specificity may be more frequent in ticks than previously thought. The presence of host-associated vector groups can significantly alter the circulation and evolutionary pathway of associated pathogens. In this paper, we explicitly test for host-associated genetic structure in I. ricinus. We analyzed genetic variability at 11 microsatellite markers in a large sample of ticks collected directly from trapped wild animals (birds, rodents, lizards, wild boar and roe deer) at five sites in Western and Central Europe. We found significant levels of genetic structure both among host individuals and among host types within local populations, suggesting that host use is not random in I. ricinus. These results help explain previous patterns of structure found in off-host tick samples, along with epidemiological observations of Lyme disease.
硬蜱属的蓖子硬蜱是一种欧洲蜱，可传播多种病原体，包括引起莱姆病的细菌（几种伯氏疏螺旋体复合种）。这种蜱已被认为是极端广义媒介的经典范例。然而，仅从野外观察很难确定此类媒介物种的宿主关联，最近的研究表明，蜱的宿主特异性可能比以前认为的更为频繁。与宿主相关的媒介群体的存在会显著改变相关病原体的循环和进化途径。在本文中，我们明确测试了蓖子硬蜱的宿主相关遗传结构。我们分析了从西欧和中欧五个地点直接从捕获的野生动物（鸟类、啮齿动物、蜥蜴、野猪和鹿）中采集的大量蜱中 11 个微卫星标记的遗传变异性。我们发现，无论是在宿主个体之间还是在当地种群中的宿主类型之间，都存在显著的遗传结构水平，这表明蓖子硬蜱的宿主利用并非随机。这些结果有助于解释先前在非宿主蜱样本中发现的结构模式，以及莱姆病的流行病学观察。
