Davies C R, Jones L D, Nuttall P A
Am J Trop Med Hyg. 1986 Nov;35(6):1256-62. doi: 10.4269/ajtmh.1986.35.1256.
Thogoto (THO) virus, a candidate orthomyxovirus, replicated in and was transmitted by larvae, nymphs, and adults of the brown ear tick, Rhipicephalus appendiculatus. Larvae fed on viremic hamsters (10(7-8) PFU/ml blood) acquired an average of 10(2.5) PFU per tick. Following engorgement the titer dropped to 10(1.9) PFU on day 2 but increased by day 6 to 10(3.3) PFU. Virus survived transstadially in these ticks as demonstrated by the fact that, on day 10, newly moulted nymphs contained, on average, 10(3.5) PFU/tick. When 10 such infected nymphs were placed on a hamster a fatal infection of the animal developed involving a viremia of 10(6.7) PFU/ml blood. Another group of 6 infected nymphs did not elicit a detectable viremia in a hamster, or cause death. However the animal seroconverted to THO, virus indicating that virus transmission had occurred. Following acquisition of THO virus at the larval stage, virus was detected in adult ticks 138 days later. Uninfected nymphs fed on viremic hamsters acquired an average of 10(4) PFU/nymph. No virus was detected in the nymphs 4 days post-engorgement. Virus was, however, recovered by 6 days post-engorgement (10(4.7) PFU/nymph). Virus persisted transstadially as shown by the presence of an average of 10(3.4) PFU in newly moulted adults. Three groups of these infected adults (5-6 ticks/group) induced viremia in hamsters with blood titers of the order 10(2.8-3.5) PFU/ml. Virus persisted in engorged adults for up to 66 days following nymphal engorgement.(ABSTRACT TRUNCATED AT 250 WORDS)
托戈托（THO）病毒是一种正黏病毒候选毒株，可在褐耳蜱（Rhipicephalus appendiculatus）的幼虫、若虫和成虫体内复制并通过它们传播。以病毒血症期仓鼠（血液中病毒含量为10⁷⁻⁸ PFU/ml）为食的幼虫，每只蜱平均感染10²·⁵ PFU病毒。饱血后，病毒滴度在第2天降至10¹·⁹ PFU，但到第6天增加至10³·³ PFU。病毒可经变态期在这些蜱体内存活，这一事实表明，在第10天，新羽化的若虫平均每只含有10³·⁵ PFU病毒。当将10只这种感染的若虫置于一只仓鼠身上时，动物会发生致命感染，病毒血症水平达到10⁶·⁷ PFU/ml血液。另一组6只感染的若虫在仓鼠体内未引发可检测到的病毒血症，也未导致死亡。然而，该动物血清转化为针对THO病毒的抗体，表明病毒已发生传播。在幼虫阶段感染THO病毒后，138天后在成年蜱中检测到病毒。以病毒血症期仓鼠为食的未感染若虫，每只若虫平均感染10⁴ PFU病毒。饱血后4天在若虫中未检测到病毒。然而，饱血后6天可检测到病毒（每只若虫10⁴·⁷ PFU）。新羽化的成虫中平均含有10³·⁴ PFU病毒，表明病毒可经变态期持续存在。三组这些感染的成虫（每组5 - 6只蜱）在仓鼠体内引发病毒血症，血液滴度为10²·⁸⁻³·⁵ PFU/ml。若虫饱血后，病毒在饱血的成虫中可存活长达66天。（摘要截选至250字）
