Ticks from diverse genera encode chemokine-inhibitory evasin proteins

Area of Science:

• Immunology
• Molecular Biology
• Parasitology

Background:

• Ticks secrete salivary proteins to evade host immune responses.
• Evasins are tick salivary glycoproteins that neutralize host chemokines, preventing leukocyte recruitment.
• The hard tick *Rhipicephalus sanguineus* produces evasins that target host defense mechanisms.

Purpose of the Study:

• To identify and characterize new evasin sequences in various hard tick species.
• To investigate the functional role of evasins in tick-host interactions.
• To explore the therapeutic potential of evasins as anti-inflammatory agents.

Main Methods:

• Sequence similarity searches were performed to identify putative evasin sequences across Ixodidae family tick genomes and transcriptomes.
• Nine representative evasin sequences were expressed recombinantly in *Escherichia coli*.
• Chemokine-binding assays were conducted to evaluate the functional activity of expressed evasins.

Main Results:

• 257 new putative evasin sequences were identified in *Rhipicephalus*, *Amblyomma*, and *Ixodes* ticks.
• Eight of nine expressed evasins demonstrated high-affinity binding to human chemokines.
• Evasins were classified into C8 and C6 subfamilies based on conserved cysteine residues and disulfide bond patterns.
• Predicted post-translational modifications include secretion leaders, N-linked glycosylation sites, and tyrosine sulfation sites.

Conclusions:

• Chemokine-binding evasins are broadly distributed among Ixodidae ticks.
• Evasins play a significant role in subverting host immunity during tick feeding.
• These evasin proteins represent a promising source of novel anti-inflammatory therapeutics.