IRF3 and viral infectious disease: Interestingly, while infection of murine fibroblasts with the rabbit specific leporipoxvirus MYXV (Myxoma virus) can also stimulate ERK1/2 phosphorylation, the activation of this pathway renders these cells non-permissive for virus infection through the activation of the transcription factor IRF-3 (Interferon regulatory factor 3) and upregulation of IFN-β (β-Interferon) expression [9,16].