There was no significant difference in viral titer between MHC Class I6b2M-/-mice and WT mice at three and five days postinfection, indicating that MHC Class I and b2M were not required in MNV infection at early time points ( Figure 4B II-/-compared to WT mice at seven days post-infection (p = 0.04, Figure 4E ). By eight days post-infection, MLN infection was cleared. Together these data indicated that MHC Class II, and by inference CD4 T cells, were necessary for control of acute MNV infection but are not required for eventual clearance of MNV infection.