Studies of MNV pathogenesis reveal an important role for interferon (IFN) and STAT-1 mediated innate immunity in resistance to infection and MNV induced lethality [27, 31] . The importance of adaptive immunity in control of MNV infection is indicated by the observation that RAG1-/-mice develop persistent MNV infection while wild type (WT) mice can clear infection with some strains of MNV [9, 27, 31] .