RmTIL, a cysteine-rich protein as a putative microbiota modulator from Rhipicephalus microplus tick

Area of Science:

• Parasitology
• Molecular Biology
• Biochemistry

Background:

• The cattle tick, Rhipicephalus microplus, causes substantial economic losses globally.
• Understanding tick-specific proteins is crucial for developing control strategies.

Purpose of the Study:

• To identify and characterize immunogenic proteins in Rhipicephalus microplus.
• To investigate the function of a novel trypsin inhibitor-like (TIL) protein (RmTIL) in tick biology and reproduction.

Main Methods:

• Phage display and third-generation sequencing (TGS) for protein identification.
• Recombinant protein expression and functional assays for protease inhibition.
• RNA interference (RNAi) for gene silencing and assessment of reproductive and microbial impacts.

Main Results:

• A novel cysteine-rich protein, RmTIL, with a trypsin inhibitor-like (TIL) domain was identified.
• Recombinant RmTIL inhibited host proteases (human neutrophil elastase, cathepsin G) and subtilisin A.
• Gene silencing of RmTIL affected tick egg viability and altered ovarian and egg bacterial loads, impacting host-microbe interactions and embryo development pathways.

Conclusions:

• RmTIL is an immunogenic protein essential for Rhipicephalus microplus.
• RmTIL plays dual roles in inhibiting host proteases and regulating tick microbiota, both vital for tick survival and reproduction.