TRIM63 and infection: To directly test whether the IRF sites in the MCMV enhancer interact with their cognate factors in the context of infection we performed a chromatin immunoprecipitation (ChIP) experiment firstly under low stringency conditions (S10 A Fig) using antibodies against IRFs 1, 3, 5 and 7 to pull down DNA-IRF complexes formed in infected RAW264.7 cells after 24 hpi.