Ixodes ticks: Serum species sensitivity of anticomplement activity

Ixodid ticks feed for extended periods of up to 2 weeks or more. To complet e engorgement, they must overcome their host's innate immune mechanisms of which the complement system is a major component. Using in vitro assays, sa livary gland extracts of the ixodid ticks, Ixodes ricinus, I. hexagonus, an d I. uriae, were shown to inhibit activity of the alternative pathway of co mplement. The ability of the different Ixodes species to inhibit complement activity varied with the animal species used as a complement serum source. Serum species sensitivity correlates to the reported host range of the tic k species tested. (C) 1999 Academic Press.