Akari Therapeutics, Plc, formerly Celsus Therapeutics Plc, is a clinical-stage biopharmaceutical company. It is focused on the development and commercialization of treatments for a range of rare and orphan autoimmune and inflammatory diseases caused by dysregulation of complement component 5 (C5), including paroxysmal nocturnal hemoglobinuria, Guillain Barre syndrome and atypical Hemolytic Uremic Syndrome. Its lead drug, Coversin, a complement inhibitor, acts on complement C5, preventing release of C5a and formation of C5b-9. Coversin is a recombinant small protein derived from a protein discovered in the saliva of the Ornithodoros moubata tick, where it modulates the host immune system to allow the parasite to feed without alerting the host to its presence or provoking an immune response. It is conducting Phase Ib clinical trial of Coversin. It focuses on rare and orphan diseases, including disease states spanning hematology, nephrology, transplantation, neurology and ophthalmology.