Changes in immunity to Ixodes ricinus by rabbits infested at different levels

Area of Science:

• Veterinary Entomology
• Immunology
• Parasitology

Background:

• Host immune responses to tick infestations are crucial for controlling tick populations.
• Understanding the dynamics of host resistance and susceptibility is vital for managing tick-borne diseases.

Purpose of the Study:

• To investigate the impact of different intensities of Ixodes ricinus adult tick infestations on rabbit host resistance.
• To analyze the effects of infestation levels on tick biology and host immune parameters.

Main Methods:

• Rabbits were subjected to varying numbers of Ixodes ricinus adult tick infestations.
• Tick feeding, egg production, and embryogenesis were monitored.
• Lymphocyte proliferation (blastogenic response) and specific antibody production against tick antigens were assessed.
• Non-specific lymphocyte proliferation was evaluated using concanavalin A.

Main Results:

• Higher tick burdens (high infestation) initially perturbed tick feeding and egg production more than lower burdens (low infestation).
• Embryogenesis was affected only in ticks from high infestation rabbits.
• Host resistance increased significantly in low infestation rabbits by the third infestation, surpassing high infestation rabbits.
• Specific antibody responses were highest in high infestation rabbits, while lymphocyte proliferation varied with infestation stage and level.
• Non-specific lymphocyte proliferation decreased during early infestations in both groups.

Conclusions:

• Ixodes ricinus infestation elicits dose-dependent host immune responses.
• Lower tick burdens can induce a more robust and sustained host resistance compared to higher burdens.
• Tick-induced immunosuppression may play a role in the host-parasite interaction, warranting further investigation.