CD4 and infection: In mice, RSV-specific antibodies appeared to have only a minor role in the resolution of infection (33), and cellular immune responses are mainly thought to play an important role in clearing RSV, since RSV clearance from the lung could be mediated by an adoptive RSV-specific T-cell transfer in infected nu/nu mice (8) and duration of RSV shedding was shortened in the presence of RSV-specific CD4 and CD8 T cells (10).