Crosstalk between the Type 1 Interferon and Nuclear Factor Kappa B Pathways Confers Resistance to a Lethal Virus Infection

Nuclear factor kappa B (NF-kappa B) and type 1 interferon (T1-IFN) signaling are innate immune mechanisms activated upon viral infection. However, the role of NF-kappa B and its interplay with T1-IFN in antiviral immunity is poorly understood. We show that NF-kappa B is essential for resistance to ectromelia virus (ECTV), a mouse orthopoxvirus related to the virus causing human smallpox. Additionally, an ECTV mutant lacking an NF-kappa B inhibitor activates NF-kappa B more effectively in vivo, resulting in increased proinflammatory molecule transcription in uninfected cells and organs and decreased viral replication. Unexpectedly, NF-kappa B activation compensates for genetic defects in the T1-IFN pathway, such as a deficiency in the IRF7 transcription factor, resulting in virus control. Thus, overlap between the T1-IFN and NF-kappa B pathways allows the host to overcome genetic or pathogen-induced deficiencies in T1-IFN and survive an otherwise lethal poxvirus infection. These findings may also explain why some pathogens target both pathways to cause disease.