Serpins in the Spotlight: Novel Bioinformatic Insights Into Hyalomma dromedarii Sialotranscriptome

Ticks pose a significant global threat to human and animal health as vectors of numerous pathogens, including bacteria, viruses, and parasites. Beyond their harmful impact, tick salivary glands contain serine protease inhibitors (serpins) known for their potential pharmaceutical properties. Traditional methods for studying tick serpins are labor-intensive, but recent advancements in bioinformatics have enabled comprehensive analyses of these molecules. In this study, we employed in silico tools to identify, classify, and analyze serpins encoded within the sialotranscriptome of the camel tick, Hyalomma dromedarii. Through sequence analysis, conserved motifs and domains have been identified, shedding light on evolutionary relationships and functional conservation among serpins both within and between tick species. The complexity of H. dromedarii serpins (HDS) exceeded prior expectations, with the identification of 15 transcripts exclusively expressed in male and 4 transcripts in female H. dromedarii salivary glands, while 91 transcripts are common to both genders. Interestingly, each HDS has a distinct reactive center loop (RCL) sequence at the protein sequence level. These RCL sequences extend from P17 to P4', are similar to those of other serpins, comprise 21 amino acids, and are situated near the C-terminus. All RCLs feature a diverse array of eight amino acid residues at the P1 sites, with the majority (47.06%) having polar basic residues. Moreover, our predictions imply that some HDSs may exert regulatory control over a wide array of proteolytic pathways, indicating their potential involvement in modulating numerous biological processes. Overall, our findings provide valuable insights into tick serpins and lay a solid foundation for future research aiming to exploit these molecules for the development of novel therapeutics and vaccines against tick-borne diseases.