土耳其东色雷斯的龟类和埃及血蜱中的克里米亚-刚果出血热病毒：潜在的隐匿传播周期。
Crimean-Congo hemorrhagic fever virus in tortoises and Hyalomma aegyptium ticks in East Thrace, Turkey: potential of a cryptic transmission cycle.
机构信息
Galveston National Laboratory, Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.
Department of Biology, Tekirdag Namik Kemal University, Tekirdag, Turkey.
出版信息
Parasit Vectors. 2020 Apr 19;13(1):201. doi: 10.1186/s13071-020-04074-6.
BACKGROUND
Recent reports have demonstrated the presence of Crimean-Congo hemorrhagic fever virus (CCHFV) genomic material in Hyalomma aegyptium ticks feeding primarily on tortoises belonging to the genus Testudo. This raises the question if these ticks and their hosts play a role in the natural transmission dynamics of CCHFV. However, the studies are limited, and assessing the relevance of H. aegyptium in perpetuating the virus in nature, and a potential spillover to humans remains unknown. This study aimed to detect CCHFV in H. aegyptium ticks and their tortoise hosts in the East Thrace region of Turkey, where H. aegyptium is the most common human-biting tick and where a high density of tortoises of the genus Testudo can be found.
METHODS
During the study period, 21 blood samples from different tortoises (2 T. hermanni and 19 T. graeca), 106 tick pools (containing 448 males, 152 females, 93 nymphs and 60 larvae) collected from 65 tortoises (5 T. hermanni and 60 T. graeca), 38 adult unfed questing ticks (25 males and 13 females, screened individually) and 14 pools (containing 8 nymphs and 266 larvae) of immature unfed questing ticks collected from the ground were screened for CCHFV genome by nested PCR and partial genomes sequenced.
RESULTS
As a result of the screening of these 179 samples, 17 (9.5%) were detected as positive as follows: 2 of 21 blood samples (9.52%), 13 (containing 18 nymphs in 3 pools, and 52 males and 8 females in 10 pools) of 106 tick pools from tortoises (12.26%), and 2 of 38 adult questing ticks (5.26%). No positive result was determined in 14 pools of immature questing ticks.
CONCLUSIONS
Previous studies have shown that reptiles can participate in the transmission of arthropod-borne viruses, but they may contribute to different aspects of the disease ecology and evolution of tick-borne viral pathogens. Our results indicate the presence of CCHFV in questing and feeding H. aegyptium ticks as well as tortoise hosts. This may indicate that CCHFV circulates in a cryptic transmission cycle in addition to the primary transmission cycle that could play a role in the natural dynamic of the virus and the transmission to humans.
背景
最近的报告表明，在主要以龟鳖目属（Testudo）龟类为食的璃眼蜱（Hyalomma aegyptium）中存在克里米亚-刚果出血热病毒（CCHFV）的基因组物质。这引发了一个问题，即这些蜱虫及其宿主是否在 CCHFV 的自然传播动态中发挥作用。然而，相关研究有限，评估璃眼蜱在自然界中持续传播病毒的相关性以及潜在的向人类溢出的风险仍不清楚。本研究旨在检测土耳其东色雷斯地区的璃眼蜱（Hyalomma aegyptium）和其龟类宿主中是否存在 CCHFV，该地区是最常见的人类叮咬蜱虫，也是龟鳖目属龟类高密度存在的地区。
方法
在研究期间，从 65 只龟（5 只赫曼陆龟和 60 只希腊陆龟）中采集了 21 份来自不同龟类（2 只赫曼陆龟和 19 只希腊陆龟）的血液样本、106 个蜱虫样本（448 只雄性、152 只雌性、93 只若虫和 60 只幼虫）、38 只未吸血的成年游离蜱虫（25 只雄性和 13 只雌性，单独筛查）和 14 个未吸血的幼体游离蜱虫样本（8 只若虫和 266 只幼虫），通过巢式 PCR 对这些样本的 CCHFV 基因组进行筛查，并对部分基因组进行测序。
结果
对这 179 个样本进行筛查后，发现有 17 个（9.5%）样本呈阳性，具体如下：21 份血液样本中的 2 份（9.52%）、106 个来自龟类的蜱虫样本中的 13 个（3 个样本中包含 18 只若虫，10 个样本中包含 52 只雄性和 8 只雌性）以及 38 只未吸血的成年游离蜱虫中的 2 只（5.26%）。14 个未吸血的幼体游离蜱虫样本未检出阳性结果。
结论
之前的研究表明，爬行动物可以参与节肢动物传播病毒的传播，但它们可能对疾病的生态和蜱传病毒病原体的进化的不同方面做出贡献。我们的结果表明，在游离和吸血的璃眼蜱中以及龟类宿主中存在 CCHFV。这可能表明，除了主要的传播循环外，CCHFV 还在一个隐匿的循环中传播，这可能在病毒的自然动态和向人类的传播中发挥作用。
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