Evaluating the Ability of the Invasive Asian Longhorned Tick, Haemaphysalis longicornis, to Maintain and Transmit North American Tick-borne Viruses

项目概要和摘要 入侵的亚洲长角蜱，长角血蜱，原产于东亚，但最近 在美国建立了种群，并继续扩大其地理范围。这是公共 健康威胁，因为在其原产地，H.长角线虫是一种与 Heartland病毒（HRTV）和鹿蜱病毒（DTV），这是两种主要的北美蜱传病毒。 H.长角蜱传播北美蜱传白蛉病毒（HRTV）和黄病毒 (DTV)是未知的，让我们不知道这种入侵蜱物种的流行病学影响。整体 本申请的目的是评估H. longicornis获取，维护，并传送北 美洲蜱传静脉病毒和黄病毒。中心假设是H. longicornis是一个有能力的 HRTV和DTV的媒介，以及受感染的原生蜱和 未感染H.长角蜱可在没有宿主病毒血症的情况下发生。该项目的基本原理是，如果 H.长角蜱能够在蜱虫种群中维持HRTV和DTV，并将这些病毒传播给 哺乳动物宿主，我们可以开始预测这些病毒的流行病学和传播动力学的演变 在北美中心假设将通过追求两个具体目标进行检验：1）评估载体 H的能力。长角蜱的HRTV和DTV;和，2）调查是否非病毒血症传播 HRTV或DTV发生在受感染的本地蜱（美洲钝眼蜱或肩突硬蜱）之间， 在同一个宿主上感染未感染的H长角的在第一个目标下，H. longicornis将感染HRTV或 DTV和蜱中的病毒复制动力学将被检查。评估HRTV的水平传播， DTV、感染H.长角虫将接受血餐，暴露的宿主将经历血清学和病毒血症 筛选在蜕皮到下一个生命阶段后，将检测蜱虫是否存在病毒，以评估垂直 传输第二个目标是，未感染的H.将与HRTV在同一宿主上共同饲养长角蚁- 感染A. americanum或DTV感染的I.成年人肩胛肌螺杆longicornis longicornis将进行测试， 病毒存在于宿主上不同的取食接近度。所提出的研究在概念上是创新的 因为它是第一个评估H的。longicornis的载体能力，北美病毒，HRTV和 DTV，在侵入性H。最近建立的longicornis种群这一贡献 将是重要的，因为它框架的基本生物学，这种入侵蜱物种与北美 蜱传病毒，这是非常重要的，因为我们试图了解H。 在这些病毒流行的北美地区建立了长角线虫。

PROJECT SUMMARY & ABSTRACT The invasive Asian Longhorned tick, Haemaphysalis longicornis, is native to eastern Asia but recently established populations in the United States and continues to expand its geographic range. This is a public health threat, because in its native range, H. longicornis is an established vector of viruses closely related to Heartland virus (HRTV) and Deer tick virus (DTV), which are the two main North American tick-borne viruses. The capacity of H. longicornis to transmit North American tick-borne phleboviruses (HRTV) and flaviviruses (DTV) is unknown, leaving us unaware of the epidemiologic impact of this invasive tick species. The overall objective for this application is to assess the ability of H. longicornis to acquire, maintain, and transmit North American tick-borne phleboviruses and flaviviruses. The central hypothesis is that H. longicornis is a competent vector for HRTV and DTV, and co-feeding transmission of HRTV or DTV between infected native ticks and uninfected H. longicornis ticks can occur in the absence of host viremia. The rationale for this project is that if H. longicornis is capable of maintaining HRTV and DTV in tick populations and transmitting these viruses to mammalian hosts, we can begin to forecast evolving epidemiologic and transmission dynamics of these viruses in North America. The central hypothesis will be tested by pursuing two specific aims: 1) Assess the vector competence of H. longicornis ticks for HRTV and DTV; and, 2) Investigate whether non-viremic transmission of HRTV or DTV occurs between infected native ticks (Amblyomma americanum or Ixodes scapularis) co-feeding on the same host with uninfected H. longicornis. Under the first aim, H. longicornis will be infected with HRTV or DTV, and viral replication kinetics in the tick will be examined. To assess horizontal transmission of HRTV and DTV, infected H. longicornis will receive a bloodmeal and exposed hosts will undergo serology and viremia screening. After molting to the next life stage, ticks will be tested for the presence of virus to evaluate vertical transmission. For the second aim, uninfected H. longicornis nymphs will be co-fed on the same host with HRTV- infected A. americanum or DTV-infected I. scapularis adults. The H. longicornis nymphs will be tested for the presence of virus at different feeding proximities on the host. The proposed research is conceptually innovative because it is the first to evaluate H. longicornis’ vector competency for the North American viruses, HRTV and DTV, which circulate in regions where invasive H. longicornis populations recently established. This contribution will be significant because it frames the basic biology of this invasive tick species in relation to North American tick-borne viruses, which is extremely important as we seek to understand the public health implications of H. longicornis establishment in regions of North America where these viruses are endemic.