The B6 WT model also differs from the IFNAR KO model in the type of cellular infiltration and immune response in the CNS at the peak of infection, with IFNAR KO displaying extensive infiltration of neutrophils and macrophage as well as upregulation of inflammatory genes such as IL-6, TNFa and IL-1, whereas B6 WT mice show cellular infiltrates composed primarily of T cells and upregulation of genes associated with Th1 CD4+T cells and IFN-driven cytotoxic CD8+ T cell responses. The gene discussed is CD4; the disease is infection.