Surveillance of Borrelia miyamotoi-carrying ticks and genomic analysis of isolates in Inner Mongolia, China

Abstract

Background Borrelia miyamotoi is a newly described relapsing fever spirochete transmitted by ixodid tick species. Little is known about the prevalence of B. miyamotoi infections in humans and ticks in Inner Mongolia, China. Therefore, we investigated the prevalence of B. miyamotoi in Ixodes persulcatus ticks, and we aimed to isolateB. miyamotoi from I. persulcatus from four regions of Greater Khingan, Inner Mongolia, China. Methods From May to June each year during the period 2016–2019, host-seeking adult I. persulcatus ticks were collected from vegetation. Genomic DNA was prepared from half of each tick body for PCR template, and the remaining half was used to cultivate B. miyamotoi in BSK-M medium. We employed quantitative real-time PCR (qPCR) to detect Borrelia DNA in the ticks and to calculate the prevalence of B. miyamotoi and infections with other borreliae. For characterization of the isolated B. miyamotoi, we performed draft genome sequencing and multilocus sequencing analysis (MLSA). Results A total of 2656 adult I. persulcatus ticks were collected. The overall prevalence of relapsing fever (RF) borreliae in ticks was 5.0% (134/2656) and that of Lyme disease (LD) borreliae was 43.8% (1164/2656). Co-infection with RF and LD borreliae was observed in 63 ticks (2.4%). Ticks that were positive for RF borreliae by qPCR were subjected to glycerophosphodiester diester phosphodiesterase gene (glpQ) PCR amplification and sequencing, through which we identified the RF borrelia specimens as B. miyamotoi. Furthermore, the B. miyamotoi strain Hetao-1 was isolated from I. persulcatus, and a draft genome sequence was obtained from the isolate. Sequencing determined the strain Hetao-1 genome to be approximately 906.1 kbp in length (28.9% average GC content), and MLSA identified the strain as ST633, which has previously been reported in Japan and Mongolia. Conclusion We detected B. miyamotoi from I. persulcatus ticks collected in Inner Mongolia, and successfully isolated a B. miyamotoi strain. To our knowledge, this is the first study to culture a B. miyamotoi isolate from China. The data on the prevalence of B. miyamotoi and other borreliae in I. persulcatus ticks will be fundamental for future epidemiological studies of B. miyamotoi disease in Inner Mongolia.

Co-infection of tick-borne bacterial pathogens in ticks in Inner Mongolia, China

“…The distribution of I . persulcatus covers Inner Mongolia [ 13 , 14 ], mainland China [ 28 ], and more specifically the southwest and northeast of China [ 29 – 32 ], among other places. D .…”

“…I. persulcatus is a typical forest tick species, which is dominant in conifer and broadleaved mixed forest, and its host range is wide, including domestic or wild medium and small mammals. The distribution of I. persulcatus covers Inner Mongolia [13,14], mainland China [28], and more specifically the southwest and northeast of China [29][30][31][32], among other places. D. nuttalli was the dominant tick species in the central and western grasslands (sample areas 2 and 3).…”

“…Located on the border of China and Russia, the Greater Hinggan Mountains in the eastern part of Inner Mongolia are rich in wildlife and have a diverse ecosystem. This region is one of the major epidemic areas of tick-borne infectious diseases in China because its unique geographical and ecological features make it an ideal habitat for ticks [3,[12][13][14]. In Inner Mongolia, and elsewhere in China and the rest of the world, limited research has been carried out on the occurrence of different genospecies in co-infections in host-questing ticks, despite progress on tick-borne infections.…”

Molecular surveillance reveals a potential hotspot of tick-borne disease in Hulunbuir City, Inner Mongolia

“…Inner Mongolia has been recognized as an endemic region of tick-borne diseases. To date, numerous studies have been carried out on tick-borne pathogens circulating in this area [6, [12][13][14][15][16][17]. However, most of these studies only focused on one or two pathogens, and exhaustive investigations on their genetic characteristics are still very few.…”

Surveillance of tick-borne bacteria infection in ticks and forestry populations in Inner Mongolia, China

“…Inner Mongolia Autonomous Region, located in northern China, is well-known for its various landscapes and is one of the natural foci of various tick-borne diseases in China (7)(8)(9)(10). Arxan, on the border between China and Mongolia in the northeastern Inner Mongolia, features abundant wildlife resources and a developed livestock industry that provides a suitable environment for ticks to survive and reproduce.…”