Microbial communities associated with the camel tick, Hyalomma dromedarii: 16S rRNA gene-based analysis

Background Hyalomma dromedarii is a very important blood-feeding ectoparasite that affects the health of camels in many parts of the world including the United Arab Emirates (UAE). The current study was conducted to assess the profile of the bacterial communities associated with H. dromedarii in the eastern part of the UAE in 2019 in comparison with ticks collected in 2010. Methods We performed 16S rRNA gene amplicon sequencing using primers flanking the V3 V4 region. Next generation sequencing was done using Illumina MiSeq platform. For each year, we analyzed 10 tick DNA pools representing 10 camel breeding locations. Principle component analysis (PCA) was conducted to determine patterns of diversity in bacterial communities. Results In 2010, we obtained 899,574 read counts (average 89,957 sequences per sample) and these formed 371 operational taxonomic units (OTUs). In 2019, we obtained 781,452 sequences (average 78,145 sequences per sample) and these formed 191 unique OTUs. In both years, 25 bacterial families with high relative abundance were found and 10 of them were common (between the two years): Moraxellaceae, Enterobacteriaceae, Staphylococcaceae, Bacillaceae, Corynebacteriaceae, Flavobacteriaceae, Francisellaceae, Muribaculaceae, Neisseriaceae, and Pseudomonadaceae. Data showed a higher diversity of tick microbiota associated with H. dromedarii in 2010 samples as compared to 2019 samples. In 2010 samples, one location (Al-Wagan) was predominant with richness of microbes whereas a different location (Omghafa) had higher richness of microorganisms in 2019 tick samples. Principle components analysis demonstrated a clear separation between the microbial communities between years with the exception of one site (Malaket) and Pearson’s r correlations exhibited that many bacterial genera were significantly correlated with each other. Conclusions The results presented here provide the first microbial community assessment in H. dromedarii in the UAE, and the first large-scale study in terms of duration and number of samples. The presence of bacterial families containing pathogenic genera and species shows that H. dromedarii could pose a serious health risk to the camels and the people who interact with them. Furthermore, our results can help future shotgun full genome sequencing studies.