1. Exploring the microbiomes of camel ticks to infer vector competence: insights from tissue-level symbiont-pathogen relationships.
- Author
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Khogali R, Bastos A, Getange D, Bargul JL, Kalayou S, Ongeso N, Verhoeven JTP, Kabii J, Ngiela J, Masiga D, and Villinger J
- Subjects
- Animals, Salivary Glands microbiology, Ticks microbiology, Coxiella genetics, Coxiella isolation & purification, Bacteria genetics, Bacteria classification, Bacteria isolation & purification, Saliva microbiology, Female, Kenya, Phylogeny, Camelus microbiology, Camelus parasitology, Symbiosis, Microbiota genetics, RNA, Ribosomal, 16S genetics, Rickettsia genetics, Rickettsia isolation & purification
- Abstract
Ticks are blood-feeding ectoparasites that harbor diverse pathogens and endosymbionts. Their microbial communities vary based on tick species, stage, sex, geographical location, surrounding environment, and tissue type. Understanding tick microbiota at the tissue level is crucial for unraveling how microbiomes are distributed in tick tissues and influence pathogen transmission. We used V1-V2 16 S rRNA gene sequencing to analyze tissue-specific bacterial compositions (hemolymph, saliva, salivary glands, and midgut) of Amblyomma gemma, Rhipicephalus pulchellus, Hyalomma dromedarii, and Hyalomma rufipes ticks collected from camels in Marsabit County, northern Kenya. The V1-V2 region of the 16 S rRNA gene effectively differentiated 43 Rickettsia africae and 16 Rickettsia aeschlimannii tick samples from other rickettsial species, as well as Coxiella endosymbionts from Coxiella burnetii. In contrast, the V3-V4 region sequences of these species could not be clearly distinguished. Coxiella endosymbionts were most common in Am. gemma and Rh. pulchellus, while Francisella endosymbionts predominated in Hyalomma ticks; both were primarily localized in the salivary glands. High abundances of Coxiella endosymbionts, as well as Pseudomonas, were associated with the absence or low abundance of Rickettsia pathogens in both Am. gemma and Rh. pulchellus, suggesting competitive interactions between these microbes. Additionally, Proteus mirabilis, an opportunistic pathogen of the urinary tract in humans, was found predominantly in Hyalomma ticks, except for the salivary glands, which were most abundant with Francisella endosymbionts. Furthermore, we detected the Acinetobacter, Pseudomonas, and Corynebacterium genera in all the tick tissues, supporting the hypothesis that these bacteria might circulate between camel blood and ticks. Saliva and hemolymph generally harbored more extracellular bacteria than the salivary glands and midgut. This study provides a new approach to unravel tick-endosymbiont-pathogen interactions by examining the tissue localization of tick-borne pathogens and symbionts in Am. gemma, Rh. pulchellus, Hy. dromedarii, and Hy. rufipes from camels in northern Kenya. Our findings establish a baseline for developing an understanding of the functional capacities of symbionts and for designing symbiont-based control strategies., Competing Interests: Declarations. Competing interests: The authors declare no competing interests. Ethics statement: The animal studies were approved by the Pwani University Ethics Review Committee (Ref: ERC/EXT/002/2020E), a license from the National Commission for Science Technology and Innovation (NACOSTI) under (Ref: NACOSTI/P/22/16467). The studies were conducted in accordance with local legislation and institutional requirements. Written informed consent was not obtained from the owners for the participation of their animals in this study prior to livestock sampling. However, verbal and non-written consent was obtained from the livestock keepers, as most of the participants were unable to read or write. Field assistants from the community assisted in translating the language from English to the local language spoken by the community members to ensure that they understood the purpose of the study and how it would benefit them., (© 2025. The Author(s).)
- Published
- 2025
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