Kaufman W R, Nuttall P A
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Exp Parasitol. 1996 Apr;82(3):316-23. doi: 10.1006/expr.1996.0039.
Saliva is considered to be the conduit by which pathogens are transmitted from blood-sucking arthropod vectors to their vertebrate hosts, but supporting evidence for this is fragmentary. To determine if Thogoto (THO) virus, a tick-borne member of the influenza virus family, is transmitted via tick saliva, and whether virus replication is a prerequisite for such transmission, two experimental conditions were compared: (1) "biological transmission" and (2) "mechanical transmission." In (1), THO virus was allowed to infect and replicate in a natural vector, Amblyomma variegatum: virus was detected in saliva collected from 3/22 (14%) ticks. In (2), virus was inoculated directly into the hemocoel with the drug used to induce salivation and saliva was collected immediately to preclude the possibility of virus replication: virus was detected in saliva collected from 31/170 (18%) ticks. The results demonstrate that THO virus is secreted in tick saliva and that virus can pass from the hemolymph to the salivary glands independently of viral replication within the tick. The comparatively low numbers of ticks that yielded virus-positive saliva samples together with the results from assays of serial saliva samples suggested that virus secretion may not be a continuous process during salivation. Ticks in which THO virus had established an infection showed an impaired secretory response compared with uninfected ticks and ticks used for mechanical transmission.
唾液被认为是病原体从吸血节肢动物媒介传播到脊椎动物宿主的渠道，但支持这一观点的证据并不完整。为了确定流感病毒家族中由蜱传播的托戈托（THO）病毒是否通过蜱唾液传播，以及病毒复制是否是这种传播的先决条件，比较了两种实验条件：（1）“生物传播”和（2）“机械传播”。在（1）中，让THO病毒在自然媒介变异革蜱中感染和复制：在从22只蜱中采集的3只（14%）蜱的唾液中检测到病毒。在（2）中，将病毒与用于诱导唾液分泌的药物一起直接接种到血腔中，并立即收集唾液以排除病毒复制的可能性：在从170只蜱中采集的31只（18%）蜱的唾液中检测到病毒。结果表明，THO病毒在蜱唾液中分泌，并且病毒可以独立于蜱体内的病毒复制从血淋巴进入唾液腺。产生病毒阳性唾液样本的蜱数量相对较少，以及连续唾液样本检测结果表明，在唾液分泌过程中病毒分泌可能不是一个连续的过程。与未感染的蜱和用于机械传播的蜱相比，感染了THO病毒的蜱的分泌反应受损。
