Tacheng tick virus 1 in ticks, livestock, and wildlife in Border Regions of China-Kazakhstan

Tacheng tick virus 1 (TcTV-1), emerging tick-borne orthonairoviruses, was firstly isolated from a tick bite patient in northwestern China. However, TcTV-1 in livestock, wildlife, and potential vectors was still unknown. From 2017 to 2021, 1495 samples included 180 engorged adult female ticks, 180 egg batches, 84 larvae, 896 adult ticks, 148 livestock blood samples, and 7 spleens from red foxes were collected from 14 counties or cities of southern and eastern Kazakhstan, and northwestern China. The samples were tested for the presence of TcTV-1 using the viral L segments by reverse transcriptase–polymerase chain reaction (RT-PCR). The infection rates of TcTV-1 were 7.78% (14/180), 3.89% (7/180), and 2.47% (2/84) in engorged adult female Hyalommaasiaticum ticks and their offsprings (eggs and larvae), respectively. 6.45% (9/148) blood samples of livestock and 14.29% (1/7) spleen samples of red foxes tested positive to TcTV-1. TcTV-1 was detected in 13.08% (34/260) adult hard ticks from Kazakhstan and 5.35% (34/636) ticks from China. This findings suggests that i) the pastured cattle, sheep, camel and wild red fox act as natural reservoirs for TcTV-1; ii) TcTV-1 is detected in genera of Hyalomma, Dermacentor, Rhipicephalus and Ixodes both originated from northwestern China and southeastern Kazakhstan; and iii) Hy. asiaticum is a potential vector of TcTV-1 due to its transovarial transmission.