We next determined whether the same cell types that were required for vaccination were also required for efficient clearance of acute infection. We focused on the role of T cells in clearance since the role of B cells in clearance has already been demonstrated [39] . To determine the role of T cells in clearance of acute MNV infection we inoculated WT, MHC Class II-/-, and MHC Class I6b2M-/-mice orally with MNV1.CW3 and measured viral titers in the distal ileum and MLN three, five, seven and 21 days post-infection ( Figure 4B-4E) .