Human Type-I Interferon Omega Holds Potent Antiviral Properties and Promotes Cytolytic CD8⁺ T Cell Responses

The type-I interferon family is well known for its critical role in innate immunity. It comprises several members, among which IFN-α₂ and IFN-β are the most extensively studied, with important antiviral and immune-modulatory functions. Recent findings linking autoantibodies against type-I interferons to severe COVID-19 suggest a potential role for IFN-ω in combating SARS-CoV-2 infection. However, little is known about human IFN-ω, as most research on this interferon has been conducted in feline models. Here, we demonstrate that human IFN-ω is secreted at levels comparable to those of IFN-α₂ or IFN-β upon stimulation with inflammatory agonists and triggers a robust antiviral response, inhibiting SARS-CoV-2 infection in vitro. Moreover, IFN-ω enhances the effector functions of antigen-specific CD8⁺ T cells primed de novo from healthy donor cells, highlighting its capacity to promote strong cellular immunity. Our results position IFN-ω as a key member of the type-I interferon family, with promising potential for therapeutic and vaccine applications.