Identification of novel Jingmen tick virus from parasitic ticks fed on a giant panda and goats in Sichuan Province, southwestern China

Distribution prediction of the habitat of Jingmen tick virus in China

Jingmen tick virus (JMTV) is widely distributed in China, and human cases have been reported. Therefore, the objectives of this study were to understand the distribution of the JMTV in suitable areas in China under the current and projected future climates. We used two pairs of JMTV primers to detect ticks in Guizhou Province via PCR and obtained data on JMTV detection in other regions through literature research. We obtained climate data from China. Finally, maximum entropy, a boosted regression tree model, and a random forest model were used for prediction. The predictive performance of the model was evaluated by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve. The JMTV positivity rate in Guizhou Province was 11.02%, which was lower than the overall national positivity rate of 16.9%. The predicted probability increased monotonically with increasing monthly mean temperature. China's high JMTV habitat is concentrated in the Daxinganling region of Heilongjiang, Shanghai, and Hainan Provinces, with the total area of high JMTV habitat accounting for 1.94% of the country's total land area. In the future, from 2021 to 2040, the area of JMTV habitat area in China will show an expanding trend. Our maps of JMTV distributions provide effective early warning information for monitoring JMTV and rapidly detecting outbreaks. The potential distribution of JMTV in China is expected to increase in size in the future, requiring continuous attention and surveillance.IMPORTANCESince the first detection of the Jingmen tick virus (JMTV) in ticks in 2014, it has been detected on several continents around the world. JMTV has also been detected in several regions of China, and human cases have been reported. JMTV has many types of hosts, including ticks, mice, bats, and turtles. It can be spread with these hosts in close proximity or over long distances. As a segmented virus, JMTV is capable not only of genetic mutation and recombination but also of genetic reassortment, resulting in changes in viral infectivity or pathogenicity. However, many uninvestigated areas still exist in China. Therefore, we investigated ticks carrying JMTV in Guizhou Province. We also predicted the distribution of JMTV in China by combining previous data.

Diversity of species and geographic distribution of tick-borne viruses in China

Introduction

Tick-borne pathogens especially viruses are continuously appearing worldwide, which have caused severe public health threats. Understanding the species, distribution and epidemiological trends of tick-borne viruses (TBVs) is essential for disease surveillance and control.

Methods

In this study, the data on TBVs and the distribution of ticks in China were collected from databases and literature. The geographic distribution of TBVs in China was mapped based on geographic locations of viruses where they were prevalent or they were detected in vector ticks. TBVs sequences were collected from The National Center for Biotechnology Information and used to structure the phylogenetic tree.

Results

Eighteen TBVs from eight genera of five families were prevalent in China. Five genera of ticks played an important role in the transmission of TBVs in China. According to phylogenetic analysis, some new viral genotypes, such as the Dabieshan tick virus (DTV) strain detected in Liaoning Province and the JMTV strain detected in Heilongjiang Province existed in China.

Discussion

TBVs were widely distributed but the specific ranges of viruses from different families still varied in China. Seven TBVs belonging to the genus Orthonairovirus of the family Nairoviridae such as Nairobi sheep disease virus (NSDV) clustered in the Xinjiang Uygur Autonomous Region (XUAR) and northeastern areas of China. All viruses of the family Phenuiviridae except Severe fever with thrombocytopenia syndrome virus (SFTSV) were novel viruses that appeared in the last few years, such as Guertu virus (GTV) and Tacheng tick virus 2 (TcTV-2). They were mainly distributed in the central plains of China. Jingmen tick virus (JMTV) was distributed in at least fourteen provinces and had been detected in more than ten species of tick such as Rhipicephalus microplus and Haemaphysalis longicornis, which had the widest distribution and the largest number of vector ticks among all TBVs. Parainfluenza virus 5 (PIV5) and Lymphatic choriomeningitis virus (LCMV) were two potential TBVs in Northeast China that could cause serious diseases in humans or animals. Ixodes persulcatus carried the highest number of TBVs, followed by Dermacentor nuttalli and H. longicornis. They could carry as many as ten TBVs. Three strains of Tick-borne encephalitis (TBEV) from Inner Mongolia Province clustered with ones from Russia, Japan and Heilongjiang Province, respectively. Several SFTSV strains from Zhejiang Province clustered with strains from Korea and Japan. Specific surveillance of dominant TBVs should be established in different areas in China.