Li C, et al. J Vet Sci. 2025 Feb;26:e19. https://doi.org/10.4142/jvs.24196

The CYP450 enzyme is a superfamily enzyme ubiquitously found in nearly all organisms, playing a vital role in the metabolism of both endogenous and exogenous compounds, and in biosynthesis. Unfortunately, an understanding of its classification, functions, expression characteristics, and other biological traits in Hyalomma asiaticum, a vector for Crimean–Congo Hemorrhagic Fever, as well as of the genes implicated in its natural product metabolism, is lacking. Towards this end, this study has identified 120 H. asiaticum CYP450 genes via transcriptome data in the face of a joint genome threat from terpinolene. The proteins these genes encode are of higher molecular weight, devoid of a signal peptide, and composed of unstable hydrophobic proteins principally containing 1–3 variable transmembrane regions. Phylogenetic evolution classifies these H. asiaticum CYP450 genes into four subfamilies. These genes all encompass complete CYP450 conserved domains, and five specific conserved motifs, albeit with different expression levels. GO and KEGG annotation findings suggest a widespread distribution of these CYP450 genes in many physiological systems, predominantly facilitating lipid metabolism, terpenoid compound metabolism, and polyketone compound metabolism, as well as cofactor and vitamin metabolism at a cellular level. Molecular docking results reveal a hydrophobic interaction between the ARG-103, ARG-104, LEU-106, PHE-109, and ILE-119 amino acid residues in CYP3A8, which is primarily expressed in the fat body, and terpinolene, with a notably up-regulated expression, with affinity = −5.6 kcal/mol. The conservation of these five key amino acid residues varies across 12 tick species, implying differences in terpinolene metabolism efficacy among various tick species. This study thereby fills an existing knowledge gap regarding the biological characteristics of H. asiaticum CYP450 genes and paves the way for further research into the functions of these particular genes.

The cytochrome p450 gene family is widely involved in various biological processes in arthropods. Tick p450s are often associated with chemical acaricides, but knowledge of their involvement in the metabolism of plant-derived essential oil components is limited. In this study, we identified the non-redundant number of p450 transcripts (NRNPTs) from Haemaphysalis longicornis and Hyalomma asiaticum under the Cymbopogon citratus essential oil (CCEO) and terpinolene stress using de novo transcriptome data, respectively. In this study, we identified and characterized the NRNPTs of Ha. longicornis and Hy. asiaticum. Their gene expression patterns and biological functions under CCEO and terpinolene stress were further analyzed. Finally, Hy. asiaticum NRNPTs (87) were more numerous than Ha. longicornis (58). Phylogenetic analyses showed that NRNPTs of both Hy. asiaticum and Ha. longicornis could be categorized in clan 2, clan 3, clan 4, and clan mito, this data comes from the NRNPTs. Phylogenetic analyses showed that NRNPTs of both Hy. asiaticum and Ha. longicornis could be categorized in clan 2, clan 3, clan 4, and clan mito. p450 members of both were most distributed in clan 3. In addition, one Hy. asiaticum NRNPT was identified as belonging to the new classification clan 20 (HyasCYP20A1). The biological functions and pathways of p450 family members enriched in Hy. asiaticum and Ha. longicornis under different exogenous substance stresses were different, and the expression patterns of these genes were inconsistent. Molecular docking results showed that Ha. longicornis p450 members (HaloCYP3A4 and HaloCYP4B1), which were significantly up-regulated under CCEO stress, as well as Hy. asiaticum HyasCYP24A1 and HyasCYP4V2 (the HaloCYP3A4 and HaloCYP4B1 homologous genes), encode proteins that differ in their ability to metabolize CCEO components, but they all bind well to Germacrene D and naphthalene. Our study enriches the knowledge of the involvement of p450 family members of different tick species in the metabolism of essential oil components of plants, and provides a theoretical basis for further in-depth studies on the function of tick p450 enzymes.

Background: Hyalomma asiaticum , which acts as a vector of zoonotic pathogens, relies on its innate immune system for defense. Methods: Unfed adult female H. asiaticum ticks were injected with Escherichia coli (Gram-negative) or Staphylococcus aureus (Gram-positive), with PBS-injected ticks as controls. After 24 h, RNA sequencing (RNA-Seq) was performed to compare transcriptomic profiles. Differential expression analysis, KEGG pathway enrichment, and phylogenetic characterization of defensin genes were conducted. RT-qPCR was used to validate selected defensin expression levels. Results: Transcriptome assembly yielded 195,132 unigenes. Principal component analysis (PCA) clearly separated the PBS control, E. coli -challenged (EC), and S. aureus -challenged (SA) groups. A total of 4,294 and 4,582 differentially expressed genes (DEGs) were identified in the EC and SA groups, respectively, compared to the PBS control. KEGG pathway enrichment analysis revealed that the MAPK signaling pathway and the Ras signaling pathway were commonly activated in both infection groups. In contrast, the lysosome pathway was significantly enriched among down-regulated DEGs in both EC and SA groups. Fifteen putative defensin genes were identified from the transcriptome, featuring conserved RVRR, CXXXC and CXC motifs. Several of these defensin isoforms were significantly up-regulated following bacterial challenge, indicating their involvement in the antibacterial response. Conclusion: This comparative transcriptomic study provides a comprehensive characterization of the defensin repertoire and immune signaling responses of H. asiaticum to Gram-negative and Gram-positive bacterial challenges. The shared activation of the MAPK pathway, together with significantly enrichment of Ras signaling pathways, reveals both common and distinct antibacterial defense strategies. The strong up-regulation of defensins and the down-regulation of lysosome highlight key transcriptional events. These findings offer a valuable resource for understanding tick innate immunity and may inform future interventions for tick-borne disease control.

Zhao X, et al. J Vet Sci. 2026 ;27:e56. https://doi.org/10.4142/jvs.25152