Influenza viral load in lung tissues and BAL. Quantitation of influenza RNA was performed by RT-qPCR at day 23, 25 and 28 PI (corresponding to day 2, 4 and 7 after pH1N1 inoculation). Bars indicate average values of positive samples in genome equivalent copies (GEC) of plasmid per swab in group Mock/pH1N1 for lung tissue (A) and BAL (B). The number of positive samples from the total number of animals was indicated above each bar. Samples from animals in groups Mock/Mock and SwH1N1/pH1N1 were all below the detection limit, indicated by the dotted line. Error bars represent one SD above and below the mean.