Serpins (serine protease inhibitors) are a large family of structurally related proteins found in
a wide variety of organisms, including hematophagous arthropods. Protein analyses
revealed that Iris, previously described as an immunomodulator secreted in the tick saliva, is
related to the leukocyte elastase inhibitor and possesses serpin motifs, including the
reactive center loop (RCL), which is involved in the interaction between serpins and serine
proteases. Only serine proteases were inhibited by purified recombinant Iris (rIris), whereas …