PDF(Pubmed)
Abstract：
BACKGROUND: Powassan virus, a North American tick-borne flavivirus, can cause severe neuroinvasive disease in humans. While Ixodes scapularis are the primary vectors of Powassan virus lineage II (POWV II), also known as deer tick virus, recent laboratory vector competence studies showed that other genera of ticks can horizontally and vertically transmit POWV II. One such tick is the Haemaphysalis longicornis, an invasive species from East Asia that recently established populations in the eastern USA and already shares overlapping geographic range with native vector species such as I. scapularis. Reports of invasive H. longicornis feeding concurrently with native I. scapularis on multiple sampled hosts highlight the potential for interspecies co-feeding transmission of POWV II. Given the absence of a clearly defined vertebrate reservoir host for POWV II, it is possible that this virus is sustained in transmission foci via nonviremic transmission between ticks co-feeding on the same vertebrate host. The objective of this study was to evaluate whether uninfected H. longicornis co-feeding in close proximity to POWV II-infected I. scapularis can acquire POWV independent of host viremia.
METHODS: Using an in vivo tick transmission model, I. scapularis females infected with POWV II (\"donors\") were co-fed on mice with uninfected H. longicornis larvae and nymphs (\"recipients\"). The donor and recipient ticks were infested on mice in various sequences, and mouse infection status was monitored by temporal screening of blood for POWV II RNA via quantitative reverse transcription polymerase chain reaction (q-RT-PCR).
RESULTS: The prevalence of POWV II RNA was highest in recipient H. longicornis that fed on viremic mice. However, nonviremic mice were also able to support co-feeding transmission of POWV, as demonstrated by the detection of viral RNA in multiple H. longicornis dispersed across different mice. Detection of viral RNA at the skin site of tick feeding but not at distal skin sites indicates that a localized skin infection facilitates transmission of POWV between donor and recipient ticks co-feeding in close proximity.
CONCLUSIONS: This is the first report examining transmission of POWV between co-feeding ticks. Against the backdrop of multiple unknowns related to POWV ecology, findings from this study provide insight on possible mechanisms by which POWV could be maintained in nature.
METHODS: Using an in vivo tick transmission model, I. scapularis females infected with POWV II (\"donors\") were co-fed on mice with uninfected H. longicornis larvae and nymphs (\"recipients\"). The donor and recipient ticks were infested on mice in various sequences, and mouse infection status was monitored by temporal screening of blood for POWV II RNA via quantitative reverse transcription polymerase chain reaction (q-RT-PCR).
RESULTS: The prevalence of POWV II RNA was highest in recipient H. longicornis that fed on viremic mice. However, nonviremic mice were also able to support co-feeding transmission of POWV, as demonstrated by the detection of viral RNA in multiple H. longicornis dispersed across different mice. Detection of viral RNA at the skin site of tick feeding but not at distal skin sites indicates that a localized skin infection facilitates transmission of POWV between donor and recipient ticks co-feeding in close proximity.
CONCLUSIONS: This is the first report examining transmission of POWV between co-feeding ticks. Against the backdrop of multiple unknowns related to POWV ecology, findings from this study provide insight on possible mechanisms by which POWV could be maintained in nature.
摘要：
背景：Powassan病毒，一种北美蜱传黄病毒,会导致人类严重的神经侵袭性疾病.虽然肩capularis是Powassan病毒谱系II（POWVII）的主要载体，也被称为鹿蜱病毒，最近的实验室矢量能力研究表明，蜱的其他属可以水平和垂直传播POWVII。一种这样的蜱虫是长毛钩虫，一种来自东亚的入侵物种，最近在美国东部建立了种群，并且已经与诸如肩胛骨I等本地媒介物种具有重叠的地理范围。在多个采样宿主上，侵袭性H.longicornis与天然I.cap虫同时摄食的报道突显了POWVII的种间共同摄食传播的潜力。鉴于缺乏明确定义的POWVII脊椎动物储库宿主，这种病毒有可能通过在同一脊椎动物宿主上共同饲养的壁虱之间的非病毒传播而在传播灶中持续存在。这项研究的目的是评估与POWVII感染的肩胛骨I紧密接近的未感染H.longicornis共食是否可以独立于宿主病毒血症获得POWV。
方法：使用体内滴答传播模型，I.将感染POWVII的肩胛骨雌性（“供体”）与未感染的H.longicornis幼虫和若虫（“受体”）共同饲喂小鼠。供体和受体蜱以不同的顺序感染小鼠，通过定量逆转录聚合酶链反应（q-RT-PCR）对血液中的POWVIIRNA进行临时筛查来监测小鼠的感染状态。
结果：在以病毒血症小鼠为食的受体H.longicornis中，POWVIIRNA的患病率最高。然而,非病毒血症小鼠也能够支持POWV的共同喂养传播，如通过在分散在不同小鼠中的多个长柄H.longicornis中检测到的病毒RNA所证明的。在壁虱摄食的皮肤部位但不在远端皮肤部位检测到病毒RNA，表明局部皮肤感染促进了POWV在紧邻的供体和受体共同摄食的壁虱之间的传播。
结论：这是第一份研究POWV在共饲养蜱之间传播的报告。在与POWV生态学有关的多个未知因素的背景下，这项研究的发现为POWV在自然界中维持的可能机制提供了见解。
方法：使用体内滴答传播模型，I.将感染POWVII的肩胛骨雌性（“供体”）与未感染的H.longicornis幼虫和若虫（“受体”）共同饲喂小鼠。供体和受体蜱以不同的顺序感染小鼠，通过定量逆转录聚合酶链反应（q-RT-PCR）对血液中的POWVIIRNA进行临时筛查来监测小鼠的感染状态。
结果：在以病毒血症小鼠为食的受体H.longicornis中，POWVIIRNA的患病率最高。然而,非病毒血症小鼠也能够支持POWV的共同喂养传播，如通过在分散在不同小鼠中的多个长柄H.longicornis中检测到的病毒RNA所证明的。在壁虱摄食的皮肤部位但不在远端皮肤部位检测到病毒RNA，表明局部皮肤感染促进了POWV在紧邻的供体和受体共同摄食的壁虱之间的传播。
结论：这是第一份研究POWV在共饲养蜱之间传播的报告。在与POWV生态学有关的多个未知因素的背景下，这项研究的发现为POWV在自然界中维持的可能机制提供了见解。
