Variation in the Microbiota of Ixodes ticks with geography, species and sex illumina. Meshnick Ixodes ticks NY CT NC

Ixodes scapularis is the principle vector of Lyme disease in the East coast and upper Midwest regions of the United States, yet the tick is also present in the Southeast, where Lyme disease is absent or rare. A closely related species, I. affinis also carries the pathogen in the South but does not seem to transmit to humans. In order to better understand the geographic diversity of the tick, we analyzed the microbiota of 104 adult I. scapularis and 13 adult I. affinis ticks captured in 19 locations in South Carolina, North Carolina, Virginia, Connecticut and New York. Initially ticks from 4 sites were analyzed by 454-pyrosequencing. Subsequently, ticks from these sites plus 15 others were analyzed by Illumina MiSeq. By both analyses female tick microbiomes were significantly less diverse than those of male ticks. The dissimilarity between tick microbiomes increased with distance between sites and the state in which a tick was collected could be inferred from its microbiota. The genus Rickettsia was prominent in all locations. Borrelia was also present in most locations, and was especially high in one site in Western Virginia. In contrast, Enterobacteriaceae was very common in North Carolina I. scapularis but uncommon in I. scapularis from other sites or in North Carolina I. affinis. These data suggest substantial variations in the Ixodes microbiota associated with geography, species, and sex.

肩突硬蜱（Ixodes scapularis）是美国东海岸及上中西部地区莱姆病的主要传播媒介，该蜱类在东南部地区亦有分布，但该区域莱姆病的发病情况极为罕见或几乎不存在。与其近缘的安氏硬蜱（I. affinis）虽可携带莱姆病的致病病原体，但似乎无法将其传播给人类。为更好地解析该蜱类的地理多样性，本研究对采集自美国南卡罗来纳州、北卡罗来纳州、弗吉尼亚州、康涅狄格州及纽约州共19个采样点的104只成年肩突硬蜱与13只成年安氏硬蜱的微生物组进行了分析。最初，研究人员采用454焦磷酸测序技术对4个采样点的蜱类样本完成了初步分析；后续又结合Illumina MiSeq测序平台，对上述4个采样点及新增的15个采样点的蜱类样本开展了进一步测序分析。两种测序方法均显示，雌性蜱类的微生物组多样性显著低于雄性蜱类。蜱类微生物组的群落差异随采样点间距的增加而增大，且可通过蜱类的微生物组特征推断其采集地所属的州。立克次体属（Rickettsia）在所有采样点均为优势类群。疏螺旋体属（Borrelia）在多数采样点亦有检出，且在弗吉尼亚州西部的某一采样点中丰度极高。与之形成鲜明对比的是，肠杆菌科（Enterobacteriaceae）在北卡罗来纳州的肩突硬蜱样本中极为常见，但在其他采样点的肩突硬蜱样本，或是北卡罗来纳州的安氏硬蜱样本中则较为少见。本研究数据表明，硬蜱属的微生物组存在显著的地理、物种及性别相关差异。