Central Research Institute of Epidemiology, 111123, Novogireevskaya st. 3A, Moscow, Russia.
Research Institute of Applied Biology of Guinea, Pastoria, CREMS, Kindia, Guinea.
Acta Trop. 2021 Feb;214:105790. doi: 10.1016/j.actatropica.2020.105790. Epub 2020 Dec 9.
Ngari virus is a mosquito-borne virus belonging to the genus Orthobunyavirus (Peribunyaviridae family). This virus is pathogenic to humans and causes severe illness. Ngari virus is present in several African countries, including Madagascar. Here, we report the detection of Ngari virus in ixodid ticks collected from cows in Guinea. A tick survey was conducted in March-November of 2018 in six regions of Guinea. The sample comprised 710 pools, with a total of 2067 ticks belonging to five species collected from 197 cows. At the initial stage, we screened a subsample of tick pools of vector-borne viruses with a multiplex genus-specific primer panel. In the second stage of the study, we narrowed the search and screened all the samples by qPCR for the detection of Ngari virus. All positive samples were sequenced with primers flanking Ngari virus-specific fragments on the S and M segments. We found Ngari virus in 12 pools that were formed from engorged ticks collected from livestock in three villages of the Kindia and Kankan regions. Sequencing of the S and M segments confirmed that the detected viruses belong to Ngari virus, and the viruses were most similar to the strain Adrar, which was isolated in Mauritania. We detected viral RNA in ticks of the following species: Amblyomma variegatum, Rhipicephalus geigyi, and Rh. (Boophilus) spp. There is no evidence that ixodid ticks are competent vectors of the Ngari virus. Most likely, the ticks obtained the virus through blood from an infected host. The study of engorged ticks can be recommended as a simpler approach for the wide screening of the Ngari virus and subsequent testing of cattle and mosquitos in those locations where the PCR-positive ticks were collected.
纳里病毒是一种蚊媒病毒，属于正布尼亚病毒科（白蛉病毒科）。该病毒对人类具有致病性，可导致严重疾病。纳里病毒存在于多个非洲国家，包括马达加斯加。在这里，我们报告了在从几内亚马蹄蟹中采集的牛身上检测到纳里病毒。2018 年 3 月至 11 月，在几内的六个地区进行了蜱虫调查。样本包括 710 个池，共有 2067 只来自 197 头奶牛的属于五个物种的蜱虫。在初始阶段，我们使用多基因特异性引物组筛选了媒介传播病毒的蜱虫池亚样本。在研究的第二阶段，我们缩小了搜索范围，并通过 qPCR 对所有样本进行了筛查，以检测纳里病毒。所有阳性样本均用侧翼带有纳里病毒特异性片段的引物进行测序，用于 S 和 M 片段。我们在三个 Kindia 和 Kankan 地区村庄的牲畜上采集的饱血蜱形成的 12 个池中发现了纳里病毒。S 和 M 片段的测序证实，检测到的病毒属于纳里病毒，与在毛里塔尼亚分离的 Adrar 株最为相似。我们在以下几种蜱虫中检测到病毒 RNA：变色革蜱、卵形硬蜱和 Rh.（Boophilus）属。没有证据表明硬蜱是纳里病毒的有效媒介。很可能，这些蜱虫通过受感染宿主的血液获得了病毒。饱血蜱的研究可作为广泛筛查纳里病毒的更简单方法，随后可在采集到 PCR 阳性蜱虫的地点对牛和蚊子进行检测。
