Several studies indicate that I. ricinus ticks harbour undiscovered viruses in Europe. In this thesis, we aimed to analyse the virome of I. ricinus ticks in Slovenia. We were interested in the composition of the RNA virome, comparison between different developmental stages of ticks (larva, nymph and adult tick) and in specific geographical locations. We were interested in the presence of potentially pathogenic viruses in tick pools. We included 1056 I. ricinus ticks sampled by the flagging method in 7 statistical regions from April to September 2022. Ticks were homogenised and pooled. RNA was extracted and transcribed into ds cDNA by the SISPA method. Libraries were constructed, sequenced and a two-stage bioinformatic analysis was performed. Reads from each tick pool were classified within the orders Bunyavirales and Reovirales. Contigs were classified within the families Nairoviridae, Phenuiviridae and Partitiviridae. Infection rates within the families Nairoviridae, Phenuiviridae and Partitiviridae were the highest in adult ticks and varied between tick collection sites. Reads in one sample were mapped on the reference genome of the Uukuniemi virus. We also confirmed through reads and contigs presence of tick-borne meningoencephalitis virus. The results of the master's thesis indicate the presence of yet unidentified viruses in the I. ricinus tick virome in Slovenia. Further investigation is required to determine whether they could potentially cause diseases in humans.
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