A new type of interferon

In this recent Nature Communications paper, Chen et al. have discovered a new type of interferon, termed interferon u (upsilon), a representative of the type IV interferon family. They show that type IV interferons are expressed in zebrafish and xenopus. Orthologues were identified in in cartilaginous fish, amphibian, reptile, avian and primitive mammals, but not in humans. Involvement of the new interferon u in antiviral responses including the stimulation of interferon-stimulated genes by IFN u, was demonstrated.