The outcome and special contributions of MHC-I molecule H-2Db (65, 66), the early anti-viral CD8+T cell response to a TMEV-infection, the reaction of CD4+ T helper and effector cells as well as regulatory T cells (Tregs) (67, 68) could not be differentiated in the present study, utilizing a generalized CD28-knockout. The gene discussed is CD4; the disease is infection.