ABSTRACTSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes COVID-19, utilizes angiotensin-converting enzyme 2 (ACE2) for entry into target cells.ACE2has been proposed as an interferon-stimulated gene (ISG). Thus, interferon-induced variability inACE2expression levels could be important for susceptibility to COVID-19 or its outcomes. Here, we report the discovery of a novel, primate-specific isoform ofACE2, which we designate asdeltaACE2 (dACE2). We demonstrate thatdACE2, but notACE2, is an ISG.In vitro, dACE2, which lacks 356 N-terminal amino acids, was non-functional in binding the SARS-CoV-2 spike protein and as a carboxypeptidase. Our results reconcile current knowledge onACE2expression and suggest that the ISG-type induction ofdACE2in IFN-high conditions created by treatments, inflammatory tumor microenvironment, or viral co-infections is unlikely to affect the cellular entry of SARS-CoV-2 and promote infection.