Transformation of mouse fibroblasts alters the induction pattern of type I IFNs after virus infection

Type I interferons (IFNs) have been shown to be involved in many immune defence and inflammatory responses. We here show that IFN-β plays an absolute essential role in the efficient induction of all type I IFNs after infection of primary embryonic as well as primary adult fibroblasts with Sendai virus. In contrast, after immortalization of such fibroblasts with SV40 large T antigen, IFN-α4 can be induced independently of IFN-β. However, efficient secretion of type I IFNs even in immortalized fibroblasts is only found when the complete signalling loop is induced by IFN-β.