Characterization of ACA-01 a Chemokine-Binding Tick Evasin

The complexity of the chemokine-receptor interaction network makes it difficult to engineer targeted drug therapy. Ticks have the solution to this complexity. As a strategy to suppress the inflammatory responses of their mammalian hosts and thereby prolong their feeding and residence times, ticks have evolved the ability to produce salivary proteins, known as Evasins, which bind to host chemokines, blocking activation of chemokine receptors and preventing leukocyte migration. ACA-01 is an Evasin found in the tick species Amblyomma cajanennense. We aimed to establish that ACA-01 is a chemokine-binding protein and solve its crystal structure. We report binding of ACA-01 to a panel of six CC chemokines using a Fluorescence Anisotropy (FA) assay. After crystallization trials, we successfully obtained needles of ACA-01 protein crystals. These studies will establish a foundation for developing ACA-01 as a potential anti-inflammatory therapeutic.