Hyalomma anatolicum anatolicum (H.a. anatolicum) (Acari: Ixodidae) ticks are globally distributed ectoparasites with veterinary and medical importance. These ticks not only weaken animals by sucking their blood but also transmit different species of parasitic protozoans. Multiple factors influence these
parasitic infections including
miRNAs, which are non-coding, small regulatory
RNA molecules essential for the complex life cycle of parasites. To identify and characterize
miRNAs in H.a. anatolicum, we developed an integrative approach combining deep sequencing, bioinformatics and real-time PCR analysis. Here we report the use of this approach to identify
miRNA expression, family distribution, and
nucleotide characteristics, and discovered novel
miRNAs in H.a. anatolicum. The result showed that miR-1-3p, miR-275-3p, and miR-92a were expressed abundantly. There was a strong bias on
miRNA, family members, and
nucleotide compositions at certain positions in H.a. anatolicum
miRNA.
Uracil was the dominant
nucleotide, particularly at positions 1, 6, 16, and 18, which were located approximately at the beginning, middle, and end of conserved
miRNAs. Analysis of the conserved
miRNAs indicated that
miRNAs in H.a. anatolicum were concentrated along three diverse phylogenetic branches of bilaterians, insects and coelomates. Two possible roles for the use of
miRNA in H.a. anatolicum could be presumed based on its parasitic life cycle: to maintain a large category of
miRNA families of different animals, and/or to preserve stringent conserved seed regions with active changes in other places of
miRNAs mainly in the middle and the end regions. These might help the parasite to undergo its complex life style in different hosts and adapt more readily to the host changes. The present study represents the first large scale characterization of H.a. anatolicum
miRNAs, which could further the understanding of the complex biology of this zoonotic parasite, as well as initiate
miRNA studies in other related species such as Haemaphysalis longicornis and Rhipicephalus sanguineus of human and animal health significance.