MAPK3 and infection: To determine whether the deletion of IFNαβR from normal memory T cells prior to secondary viral infection would limit T cell attrition and/or abrogate MHC class I or Qa-1 expression, LCMV-immune UBC-Cre-ERT2+ and UBC-Cre-ERT2- IFNαβRfl/fl mice were treated with tamoxifen, then rechallenged with LCMV-Arm, as outlined in Fig 4A, or given a sham infection.