While MHCII-/- and CD4-/- mice were unable to control wild type (WT) MCMV replication, they were able to control Δm04Δm06Δm152 MCMV by day 28 post infection (Fig. 7A), indicating that the strict requirement for CD4 T cells to control SG MCMV infection no longer holds in absence of MCMV-encoded MHC class I immune evasion genes. This evidence concerns the gene CD4 and infection.