Initial studies in OX40 −/− and OX40L −/− mice independently infected with lymphocytic choriomeningitis virus (LCMV), vesicular stomatitis virus (VSV), Theiler's murine encephalomyelitis (TMEV) and influenza virus demonstrated no defect in control of viral replication or the generation of effector CD8 T cell populations (124, (145) (146) (147) (148) .