哈萨克斯坦和中亚地区 TBEV 的载体、分子流行病学和系统发育。
Vectors, molecular epidemiology and phylogeny of TBEV in Kazakhstan and central Asia.
机构信息
Center for International Health, Ludwig-Maximilians-Universität, Munich, Germany.
National Scientific Center for Highly Dangerous Infections, Almaty, Kazakhstan.
出版信息
Parasit Vectors. 2020 Oct 6;13(1):504. doi: 10.1186/s13071-020-04362-1.
BACKGROUND
In the South of Kazakhstan, Almaty Oblast' (region) is endemic for tick-borne encephalitis, with 0.16-0.32 cases/100,000 population between 2016-2018. The purpose of this study was to determine the prevalence and circulating subtypes of tick-borne encephalitis virus (TBEV) in Almaty Oblast' and Kyzylorda Oblast'.
METHODS
In 2015 we investigated 2341 ticks from 7 sampling sites for the presence of TBEV. Ticks were pooled in 501 pools and isolated RNA was tested for the presence of TBEV by RT-qPCR. For the positive samples, the E gene was amplified, sequenced and a phylogenetic analysis was carried out.
RESULTS
A total of 48 pools were TBEV-positive by the RT-qPCR. TBEV-positive ticks were only detected in three districts of Almaty Oblast' and not in Kyzylorda Oblast'. The positive TBEV pools were found within Ixodes persulcatus, Haemaphysalis punctata and Dermacentor marginatus. These tick species prevailed only in Almaty Oblast' whereas in Kyzylorda Oblast' Hyalomma asiaticum and D. marginatus are endemic. The minimum infection rates (MIR) in the sampling sites were 4.4% in Talgar, 2.8% in Tekeli and 1.1% in Yenbekshikazakh, respectively. The phylogenetic analysis of the generated sequences indicates that TBEV strains found in Almaty Oblast' clusters in the Siberian subtype within two different clades.
CONCLUSIONS
We provided new data about the TBEV MIR in ticks in Almaty Oblast' and showed that TBEV clusters in the Siberian Subtype in two different clusters at the nucleotide level. These results indicate that there are different influences on the circulating TBEV strains in south-eastern Kazakhstan. These influences might be caused by different routes of the virus spread in ticks which might bring different genetic TBEV lineages to Kazakhstan. The new data about the virus distribution and vectors provided here will contribute to an improvement of monitoring of tick-borne infections and timely anti-epidemic measures in Kazakhstan.
背景
在哈萨克斯坦南部，阿拉木图州（地区）是蜱传脑炎的地方性流行区，2016-2018 年期间每 10 万人中有 0.16-0.32 例病例。本研究的目的是确定阿拉木图州和克孜勒奥尔达州蜱传脑炎病毒（TBEV）的流行率和循环亚型。
方法
2015 年，我们在 7 个采样点调查了 2341 只蜱，以确定 TBEV 的存在。将蜱分为 501 个池，并通过 RT-qPCR 检测 RNA 中 TBEV 的存在。对阳性样本进行 E 基因扩增、测序和系统发育分析。
结果
共有 48 个 RT-qPCR 池为 TBEV 阳性。TBEV 阳性蜱仅在阿拉木图州的三个区发现，而在克孜勒奥尔达州未发现。阳性 TBEV 池存在于 Ixodes persulcatus、Haemaphysalis punctata 和 Dermacentor marginatus 中。这些蜱种仅在阿拉木图州流行，而在克孜勒奥尔达州，亚洲璃眼蜱和 D. marginatus 是地方性的。采样点的最小感染率（MIR）分别为塔尔加尔 4.4%、特凯利 2.8%和叶恩别克希卡扎卡兹 1.1%。生成序列的系统发育分析表明，阿拉木图州发现的 TBEV 株在核苷酸水平上聚类为西伯利亚亚型中的两个不同分支。
结论
我们提供了关于阿拉木图州蜱中 TBEV MIR 的新数据，并表明 TBEV 在两个不同的聚类中聚类为西伯利亚亚型。这些结果表明，哈萨克斯坦东南部对循环 TBEV 株有不同的影响。这些影响可能是由蜱传播病毒的不同途径引起的，这可能会给哈萨克斯坦带来不同的遗传 TBEV 谱系。这里提供的有关病毒分布和传播媒介的新数据将有助于改善哈萨克斯坦的蜱传感染监测和及时的防疫措施。
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