Yunnan Tropical and Subtropical Animal Virus Diseases Laboratory, Yunnan Animal Science and Veterinary Institute, Kunming, Yunnan Province, China.
Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia.
Parasit Vectors. 2019 Oct 4;12(1):464. doi: 10.1186/s13071-019-3736-9.
Bluetongue disease of ruminants is a typical insect-borne disease caused by bluetongue virus (BTV) of the genus Orbivirus (family Reoviridae) and transmitted by some species of Culicoides (Diptera: Ceratopogonidae). Recently, the detection of BTV in yaks in high altitude meadows of the Shangri-La district of Yunnan Province, China, prompted an investigation of the Culicoides fauna as potential vectors of BTV.
A total of 806 Culicoides midges were collected by light trapping at three sites at altitudes ranging from 1800 to 3300 m. The species were identified based on morphology and the DNA sequences of cytochrome c oxidase subunit 1 (cox1). PCR and quantitative PCR following reverse transcription were used to test for the presence of BTV RNA in Culicoides spp. A phylogenetic analysis was used to analyze the cox1 sequences of some specimens.
Four species dominated these collections and cox1 barcoding revealed that at least two of these appear to belong to species new to science. Culicoides tainanus and a cryptic species morphologically similar to C. tainanus dominated low altitude valley collections while C. nielamensis was the most abundant species in the high-altitude meadow. A species related to C. obsoletus occurred at all altitudes but did not dominate any of the collections. BTV RT-qPCR analysis detected BTV RNA in two specimens of C. tainanus, in one specimen closely related to C. tainanus and in one specimen closely related to C. obsoletus by barcode sequencing.
This study suggests that BTV in high altitude areas of Yunnan is being transmitted by three species of Culicoides, two of which appear to be new to science. This research may be useful in improving understanding of the effects of global warming on arboviral disease epidemiology and further study is important in research into disease control and prevention.
反刍动物蓝舌病是一种由蓝舌病毒（BTV）引起的典型虫媒病，该病毒属于呼肠孤病毒科环状病毒属，由某些库蠓属（双翅目：蠓科）传播。最近，在中国云南省香格里拉地区高海拔草地的牦牛中检测到 BTV，促使人们调查库蠓属的动物群，以确定它们是否是 BTV 的潜在传播媒介。
在海拔 1800 至 3300 米的三个地点，通过灯光诱捕共收集了 806 只库蠓。根据形态学和细胞色素 c 氧化酶亚基 1（cox1）的 DNA 序列对物种进行鉴定。采用 PCR 和逆转录定量 PCR 检测库蠓属中 BTV RNA 的存在。对一些标本的 cox1 序列进行了系统发育分析。
这四种物种在这些采集物中占主导地位，cox1 条形码显示，其中至少有两种似乎属于新的科学物种。库蠓属taiwanensis 和形态上与 C. tainanus 相似的隐种在低海拔山谷采集物中占主导地位，而 C. nielamensis 是高海拔草地中最丰富的物种。一种与 C. obsoletus 相关的物种出现在所有海拔高度，但没有在任何采集物中占主导地位。BTV RT-qPCR 分析在两例 C. tainanus 标本、一例与 C. tainanus 密切相关的标本和一例与 C. obsoletus 密切相关的标本中检测到 BTV RNA。
本研究表明，云南高海拔地区的 BTV 由三种库蠓属传播，其中两种似乎是新的科学物种。这项研究可能有助于提高对全球变暖对虫媒病流行病学影响的认识，进一步的研究对于疾病控制和预防的研究很重要。
