Complement inhibitor (PubMed:31871188). Prevents complement-mediated activation of C5 by sterically preventing direct binding of C5 to its convertase (binding with domains MG4 and MG5) (PubMed:31871188). Binds C5 at a different binding site than the other tick complement inbibitors OmCI and RaCI3, and the drug eculizumab (PubMed:31871188). Inhibits the complement in human, rat and guinea pig, and also shows a reduced inhibition in rabbit and pig (PubMed:31871188). Expressed by the salivary glands. Belongs to the CirpT family.