To assess the contribution of TGF-β on the anti-viral CD4 T cell response during a respiratory infection, we infected TGF-βRII WT and KO Stg chimeras i.n. with a recombinant influenza virus expressing the LCMV GP66–77 epitope recognized by the Stg TCR (WSN-GP33/66) (Marsolais et al., 2008). The gene discussed is CD4; the disease is respiratory tract infectious disorder.