EDNRA and pulmonary arterial hypertension: In a study for a novel PAH treatment, Dia et al. developed a vaccine (ETRQβ-002) against the ET-1 receptor (ETA) ETA peptide (ETA-002, second extracellular loop of ETA receptor, conjugated to the Qβ bacteriophage virus-like particle carrier protein, ETRQβ-002) [82].