Ovine Interferon-Alpha (IFN-α) is a type I interferon produced primarily by plasmacytoid dendritic cells and virus-infected cells in sheep (Ovis aries), where it plays a central role in early innate antiviral immunity. Upon binding to the type I interferon receptor complex (IFNAR1/IFNAR2), ovine IFN-α activates JAK/STAT signaling pathways, leading to induction of interferon-stimulated genes (ISGs) that inhibit viral replication, enhance antigen presentation, and promote activation of natural killer (NK) cells and adaptive immune responses. Ovine IFN-α is critically involved in host defense against economically significant viral infections such as bluetongue virus (BTV), ovine progressive pneumonia virus (maedi-visna; a small ruminant lentivirus), peste des petits ruminants virus (PPRV), and sheep pox virus. Viral modulation or evasion of type I interferon responses can contribute to persistence, chronic inflammation, or systemic disease. The magnitude and timing of IFN-α induction influence disease outcome, viral shedding, and vaccine responsiveness in sheep populations. In veterinary and comparative research, characterization of ovine IFN-α supports studies of lentiviral pathogenesis, arboviral disease, mucosal antiviral immunity, and type I interferon biology in ruminants, contributing to improved disease control strategies and broader understanding of antiviral immune mechanisms relevant to both animal and human health.