International Journal of Molecular Sciences Review Insights into the Role of Tick Salivary Protease Inhibitors during Ectoparasite–Host Crosstalk Mohamed Amine Jmel 1,† , Hajer Aounallah 2,3,† , Chaima Bensaoud 1, Imen Mekki 1,4, JindˇrichChmelaˇr 4, Fernanda Faria 3 , Youmna M’ghirbi 2 and Michalis Kotsyfakis 1,* 1 Laboratory of Genomics and Proteomics of Disease Vectors, Biology Centre CAS, Institute of Parasitology, Branišovská 1160/31, 37005 Ceskˇ é Budˇejovice,Czech Republic;
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[email protected] (C.B.);
[email protected] (I.M.) 2 Institut Pasteur de Tunis, Université de Tunis El Manar, LR19IPTX, Service d’Entomologie Médicale, Tunis 1002, Tunisia;
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[email protected] (Y.M.) 3 Innovation and Development Laboratory, Innovation and Development Center, Instituto Butantan, São Paulo 05503-900, Brazil;
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[email protected] † These authors contributed equally. Abstract: Protease inhibitors (PIs) are ubiquitous regulatory proteins present in all kingdoms. They play crucial tasks in controlling biological processes directed by proteases which, if not tightly regulated, can damage the host organism. PIs can be classified according to their targeted proteases or their mechanism of action. The functions of many PIs have now been characterized and are showing clinical relevance for the treatment of human diseases such as arthritis, hepatitis, cancer, AIDS, and cardiovascular diseases, amongst others. Other PIs have potential use in agriculture as insecticides, anti-fungal, and antibacterial agents.