Evasin‐3‐like anti‐chemokine activity in salivary gland extracts of ixodid ticks during blood‐feeding: a new target for tick control

Ticks exploit many evasion mechanisms to circumvent the immune control of their hosts including subversion of the communication language between cells of the immune system provided by chemokines and other cytokines. One subversive molecule secreted in the saliva of Rhipicephalus sanguineus is Evasin‐3, a structurally unique 7 kDa protein that selectively binds the neutrophil chemoattractants, CXCL8 and (with lower affinity) CXCL1. We compared anti‐human CXCL8 and anti‐mouse CXCL1/KC activities in salivary gland extracts prepared from adult Amblyomma variegatum, Rhipicephalus appendiculatus and Dermacentor reticulatus ticks during blood‐feeding. Both anti‐CXCL8 activity and anti‐CXCL1 activity were detected in all species and in both adult females and males, with consistently higher activity levels against CXCL8. These results suggest that Evasin‐3‐like activity is common amongst metastriate ixodid tick species, and provide further evidence of the importance to ticks in controlling neutrophils during blood‐feeding. As such, Evasin‐3 offers a new target for anti‐tick vaccine development.     

Changes in the lesser circulation as affected by armin

Experiments on narcotized cats have shown that intravenous administration of armine in DL50 (0.2 mg/kg) decreases the pulmonary blood flow by 52%. The reduction of the pulmonary blood flow is accompanied by a drop of pressure in the femoral artery, development of bronchoconstriction, bradycardia and arterial hypoxemia. The pressure in the lung artery remains rather high. At the beginning of intoxication the decrease of the pulmonary blood flow correlates with bronchoconstriction in a greater degree than with other indicators and as the pathological process deepens, the reduction of the pulmonary blood flow gets closely connected with bradycardia.