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Background: Ticks are obligate haematophagous ectoparasites considered second to mosquitos as vectors and reservoirs of multiple pathogens of global concern. Individual variation in tick infestation has been reported in indigenous sheep, but its genetic control remains unknown., Results: Here, we report 397 genome-wide signatures of selection overlapping 991 genes from the analysis, using ROH, LR-GWAS, XP-EHH, and F ST , of 600 K SNP genotype data from 165 Tunisian sheep showing high and low levels of tick infestations and piroplasm infections. We consider 45 signatures that are detected by consensus results of at least two methods as high-confidence selection regions. These spanned 104 genes which included immune system function genes, solute carriers and chemokine receptor. One region spanned STX5, that has been associated with tick resistance in cattle, implicating it as a prime candidate in sheep. We also observed RAB6B and TF in a high confidence candidate region that has been associated with growth traits suggesting natural selection is enhancing growth and developmental stability under tick challenge. The analysis also revealed fine-scale genome structure indicative of cryptic divergence in Tunisian sheep., Conclusions: Our findings provide a genomic reference that can enhance the understanding of the genetic architecture of tick resistance and cryptic divergence in indigenous African sheep., (© 2022. The Author(s).)

Background: Tick-borne encephalitis virus (TBEv) is a flavivirus that circulates in a complex cycle involving small mammals as amplifying hosts and ticks as vectors and reservoirs. The current study aimed to investigate the presence of TBEv in Tunisian sheep. A sample of 263 adult sheep were selected from 6 localities where Ixodes ricinus is well established. Sera were screened using ELISA for TBEv IgG detection, then the doubtful and positive sera were tested by the seroneutralisation test (SNT) and screened for West Nile Virus (WNv) IgG for cross-reaction assessment., Results: The ELISA for TBEv IgG detected one positive serum and 17 borderlines. The SNT showed one positive serum among the 18 tested, giving an overall antibody prevalence of 0.38% (95% CI = 0.07-2.12%). All but one serum tested negative to WNv ELISA. None of the sheep farmers reported neurological signs among sheep or humans in their households., Conclusions: The results may indicate the circulation of TBEv for the first time in Tunisia and in North Africa. Further studies based on either virus isolation or RNA detection, are needed to confirm the presence of TBEv in North Africa.