Variations in free radical scavenging activities and antioxidant responses in salivary glands of Hyalomma anatolicum anatolicum and Hyalomma dromedarii (Acari: Ixodidae) ticks

Aim: Hyalomma anatolicum anatolicum and Hyalomma dromedarii ticks are of major economic importance in the livestock sector as the vector of tropical theileriosis causing huge production loss, mostly in tropical countries. The release of different reactive oxygen and nitrogen species by exogenous and endogenous means can potentially induce oxidative damage to the ticks during their prolonged feeding on their vertebrate hosts. Hence, ticks need an effective free radical scavenging and antioxidant defense system for their successful feeding of a blood meal. Therefore, the present study was undertaken to evaluate the interspecies variations in antioxidant response, free radical scavenging, and anti-inflammatory activities in salivary gland extracts (SGE) of the two species as they differ considerably in relation to feeding behavior and host specificity. Materials and Methods: Tick salivary glands were dissected out under ice from semi-fed female ticks of both the species and homogenized at low temperature to prepare SGE. SGE was stored at −40°C for analysis of free radical scavenging activities and antioxidant status. Results: Significant depletion in reduced glutathione concentrations, malondialdehyde level and elevation in free radical scavenging activity, superoxide dismutase, anti-inflammatory activity were found in SGE of engorging female H. dromedarii ticks as compared to H. a. anatolicum. Conclusion: Higher antioxidant status and free radical scavenging activities in H. dromedarii might have enabled these ticks to suck more blood from the host in spite of continuous host’s immune responses. These findings about tick biology will help in improving tick control strategies.