A, B: Bodyweight loss (A) and mortality (B) of C57BL/6J WT or Daf-/- mice infected with the indicated doses of A/Puerto Rico/8/1934 with segment 4 from A/Hong Kong/1/68 (PR8-HK4). (A: Inf n = 14 and n = 10, mock n = 4 and n = 1 for WT and Daf-/- respectively; B: Inf n = 8 per group, mock n = 4 and n = 1 for WT and Daf-/- respectively). Results are expressed as mean±sd. C: Lung viral titers of C57BL/6J WT or Daf-/- mice infected with 100 PFU of PR8-HK4. Samples collected at 3 d.p.i. (n = 9 and n = 8 for WT and Daf-/- respectively) and 6 d.p.i. (n = 9 per group). Results are expressed as mean±sd. D: Immunohistochemistry detection of IAV nucleoprotein (NP) in WT or Daf-/- 3 d.p.i. with 100 PFU of PR8-HK4 (+ healthy; + infected). E: Quantification of infected bronchioli (n = 5 per group). F, G: Histological score and cell infiltration in lung parenchyma of C57BL/6J WT or Daf-/- mice infected with 100 PFU of PR8-HK4. Samples collected at 3 d.p.i. (F, Inf n = 16 and n = 18, mock n = 6 and n = 7 for WT and Daf-/- respectively) and 6 d.p.i. (G, Inf n = 13 and n = 9, mock n = 4 and n = 2 for WT and Daf-/- respectively). Results are expressed as mean±sd. Statistical analysis detailed in materials and methods.