STAT2 and severe combined immunodeficiency: Specifically, these models have included the interferon-α/β receptor knockout (IFNAR KO), the double interferon-α/β and γ receptor (IFNAGR) KO, interferon-γ receptor (IFNGR) KO, the cytoplasmic signal transducer and activator of transcription-1 protein (STAT-1) KO, the severe combined immunodeficiency (SCID) KO mice, and STAT-2 KO hamsters.