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. 2024 Jan 11:14:1331434.
doi: 10.3389/fmicb.2023.1331434. eCollection 2023.

Molecular detection of Rickettsiales and a potential novel Ehrlichia species closely related to Ehrlichia chaffeensis in ticks (Acari: Ixodidae) from Shaanxi Province, China, in 2022 to 2023

Xue Zhang  1 , Wen Lv  2 , Zhongqiu Teng  1 , Na Zhao  1 , Yue Zhou  3 , Di Ma  4 , Lin Ma  2 , Yuqing Cheng  1 , Jianjun Wei  5 , Jia He  1 , Wenke Ma  6 , Dongli Liu  2 , Tian Qin  1
Affiliations

Molecular detection of Rickettsiales and a potential novel Ehrlichia species closely related to Ehrlichia chaffeensis in ticks (Acari: Ixodidae) from Shaanxi Province, China, in 2022 to 2023

Xue Zhang et al. Front Microbiol. .

Abstract

Important tick-borne diseases include spotted fever group Rickettsia (SFGR), Anaplasma, and Ehrlichia, which cause harm to animal and human health. Ixodidae are the primary vectors of these pathogens. We aimed to analyze the prevalence and genetic diversity of SFGR, Anaplasma, and Ehrlichia species in the Ixodidae in Shaanxi Province, China. Herein, 1,113 adult Ixodidae ticks were collected from domestic cattle and goats, and detected using nested PCR. A total of four Ixodidae species were collected and Ca. R. jingxinensis (20.58%, 229/1113), A. bovis (3.05%, 34/1113), A. capra (3.32%, 37/1113), A. marginale (0.18%, 2/1113), E. sp. Yonaguni138 (0.18%, 2/1113), and a potent novel Ehrlichia species named E. sp. Baoji96 (0.09%, 1/1113) were detected. A. marginale was detected for the first time in Rhipicephalus microplus. E. sp. Baoji96 was closely related to E. chaffeensis and was first identified in Haemaphysalis longicornis. In addition, co-infection with two Rickettsiales pathogens within an individual tick was detected in 10 (1.54%) ticks. This study provides a reference for the formulation of biological control strategies for ticks and tick-borne diseases in Shaanxi Province, and could lead to an improved control effect.

Keywords: Anaplasma; Ehrlichia; Ixodidae; SFGR; Shaanxi Province.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Map of Shaanxi Province showing the locations of the study sites.
Figure 2
Figure 2
Phylogenetic trees of Rickettsia strains. The tree was constructed using MEGA 7.0 based on the nucleotide sequences of the 16S rRNA (1,188 bp), gltA (1,000 bp; encoding citrate synthase), and 17kD (440 bp, encoding the 17-kDa antigen) genes. Sequences obtained in this study are marked in red.
Figure 3
Figure 3
Phylogenetic trees of Anaplasma strains. The tree was constructed using MEGA 7.0 based on the nucleotide sequences of the 16S rRNA (1,200 bp), gltA (1,000 bp), and groEL (800 bp, encoding the 60 kDa heat shock protein) genes. Sequences obtained in this study are marked in red.
Figure 4
Figure 4
Phylogenetic trees of Ehrlichia strains. The tree was constructed using MEGA 7.0 based on the nucleotide sequences of the 16S rRNA (1,110 bp), gltA (804 bp), groEL (1,030 bp), dsb (400 bp; encoding the disulfide bond formation protein) and ftsZ (343 bp; encoding a cell division protein) genes. Sequences obtained in this study are marked in red.
Figure 5
Figure 5
The differences in the 16S rRNA gene sequences of E. sp. Baoji96 and representative strains of Ehrlichia in a 50 bp hypervariable region located at the 5′-end of the 16S rRNA gene after multiple sequence alignment.
Figure 6
Figure 6
Levels of genetic identity and divergence between E. sp. Baoji96 and Anaplasmataceae species in the 16S rRNA gene. Twenty one sequences of representative strains of all genera of Anaplasmataceae were selected. The Clustal W algorithm was used to compare these 21 sequences in pairs and to calculate the genetic distance between them. The values on the upper right are the corrected levels of nucleotide identities for 1,390 bases.
See this image and copyright information in PMC

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