Detection, Genetic Characterization, and Evolutionary Analysis of Jingmen Tick Virus in Ticks from Border Regions of Yunnan Province, China
This study reveals a high prevalence of Jingmen tick virus (JMTV) exclusively in *Rhipicephalus microplus* ticks from Yunnan's border regions, characterized by a distinct Asian lineage and unsuccessful isolation attempts, thereby highlighting significant potential public health risks in the area.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
In the borderlands where China meets its neighbors, the air is thick with the hum of insects and the rustle of livestock. Among the creatures that hitch rides on cattle are ticks, small arachnids that have long been known to carry diseases. For decades, scientists have focused on a specific group of viruses called flaviviruses, which include well-known pathogens like dengue fever and Japanese encephalitis. These viruses typically carry their genetic instructions on a single, continuous strand of RNA, a molecular blueprint that dictates how they replicate and spread. However, nature occasionally surprises us with exceptions. A relatively new discovery, the Jingmen tick virus, breaks this rule. Unlike its cousins, this virus carries its genome on four separate pieces of RNA. This segmented structure is rare among flaviviruses and suggests a different, perhaps more flexible, way of evolving. Because this virus has been found in ticks across the globe and has recently been linked to human illness in a few cases, understanding where it lives and how it moves is a matter of public health. The question remains: how widespread is this unique virus in the border regions of southwestern China, and what role do the local ticks play in its life cycle?
To answer this, a team of researchers from Kunming University and the Kunming Customs Technical Center set out to survey the cattle ticks in five border regions of Yunnan Province. Between May 2024 and August 2025, they collected 1,035 ticks from cattle grazing near the borders with Myanmar, Laos, and Vietnam. The team first had to identify exactly which species of tick they were holding. By analyzing specific genetic markers within the tick's own DNA, they confirmed the presence of three distinct species: Rhipicephalus microplus, Haemaphysalis longicornis, and Haemaphysalis bispinosa. The most common of these was Rhipicephalus microplus, which was found in every location they visited.
Once the ticks were identified, the researchers turned their attention to the virus itself. They used a highly sensitive laboratory technique to scan the ticks for the genetic signature of the Jingmen tick virus. The results were striking. Out of the 1,035 ticks tested, 733 were found to be carrying the virus, representing a positive rate of roughly 71 percent. However, this high number was not spread evenly. The virus was found exclusively in the Rhipicephalus microplus ticks; the other two species tested negative. Furthermore, the infection rate varied dramatically by location. In the Ruili area, bordering Myanmar, nearly 94 percent of the Rhipicephalus microplus ticks carried the virus. In contrast, in the Malipo area, bordering Vietnam, the rate was about 71 percent. This difference was statistically significant, suggesting that the virus is not just present but is actively circulating at very high levels in specific border zones.
The researchers then looked deeper into the genetic makeup of the virus to understand its history and relationships. Because the Jingmen tick virus has four separate segments of RNA, the team analyzed each piece individually to see if they all told the same story. They compared the genetic sequences of the virus found in their ticks against known strains from around the world. The analysis revealed that all four segments of the virus found in Yunnan belonged to a distinct lineage within the Asian group of the virus. Interestingly, the four segments did not always cluster together on the same branch of the evolutionary tree. Some segments grouped closely with strains found in other parts of China, while others showed connections to different hosts or regions. This pattern suggests that while the virus generally stays within a specific geographic and host family, its separate genetic segments can sometimes swap places or evolve independently, a process known as reassortment. This flexibility allows the virus to adapt while maintaining its core identity.
Despite finding so much viral genetic material, the team faced a significant challenge when they tried to grow the live virus in the laboratory. They attempted to infect three different types of cells commonly used for growing viruses, as well as a group of mice, with samples from the infected ticks. They hoped to see the virus multiply and cause visible changes in the cells or illness in the animals. However, the virus refused to grow. While traces of viral genetic material could be detected in the first few days of the cell cultures, the virus failed to establish a stable infection and disappeared by the third attempt. Similarly, the mice showed no signs of infection, and no virus was found in their tissues. This outcome aligns with previous findings that this virus is difficult to grow outside of its natural tick environment, likely because it relies on specific biological conditions found only in tick cells that are missing in standard laboratory setups.
The study concludes that the Jingmen tick virus is highly prevalent in the Rhipicephalus microplus ticks along the Yunnan border, particularly in the region bordering Myanmar. The virus appears to be a stable part of the local ecosystem, circulating actively among cattle and their ticks. While the researchers were unable to grow the live virus in their lab, the high rate of detection in the field confirms that the virus is a real and present factor in these border regions. The findings highlight the importance of monitoring these specific ticks, as they serve as a bridge for the virus between animals and potentially humans. The study also notes that because the sampling was concentrated heavily in one area, the overall numbers might not represent the entire province, but the evidence is clear enough to warrant continued surveillance. The work underscores that this segmented virus, with its unique genetic structure, is a persistent and evolving presence in the region, requiring careful attention from public health officials and veterinarians alike.
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