ISG15 and infection: Furthermore, key proteins that were differentially regulated during infection with these strains included IL-1B (Supplementary Figure S2B), NF-kB 2 (Supplementary Figure S2C), retinoic acid-inducible gene I (Rig-I/DDX58) (Supplementary Figure S2D) and Interferon stimulated gene 15 (ISG15) (Supplementary Figure S2E), indicative of both altered interleukin and interferon responses, all of which can be controlled by NF-kB signalling.