We corroborated this finding and extended the observation period to more than one year, by comparing viral titers of two mouse strains that lack CD4 T cells, namely MHC class II knockout (MHCII-/-) and CD4 knockout mice (CD4-/-), with wild type C57BL/6 (B6) mice at different stages post MCMV-Δm157 (herein after referred to MCMV) infection. This evidence concerns the gene CD4 and infection.