Project description:Background: Hyalomma asiaticum, which acts as a vector of zoonotic pathogens, relies on its innate immune system for defense. Methods: This study employed comparative transcriptomics to investigate defensin expression and immune pathway activation in ticks exposed to Staphylococcus aureus and Escherichia coli bacteria. Unfed adult female ticks were injected with bacteria, followed by RNA-Seq analysis after 24 h. Results: De novo assembly generated 195,132 unigenes. A total of 15 defensin genes were identified. Functional enrichment demonstrated pathogen-specific immune responses: E. coli challenge led to significant enrichment of the IMD pathway, while S. aureus stimulation resulted in enrichment of the Toll pathway. A shared response to both E. coli and S. aureus infection was the significant up-regulation of the MAPK signaling pathway (P < 0.01). Key defensin isoforms showed significant differential up-regulation, up to 8-12-fold, suggesting functional diversification. Beyond direct antimicrobial activity, defensin-associated genes were enriched in apoptosis and oxidative stress responses. Conclusions: These findings reveal distinct signaling mechanisms underlying H. asiaticum antibacterial defense and highlight defensins as multifunctional effector molecules. This study offers a preliminary reference for comprehending immune mechanisms of H. asiaticum.
