Figure 1. Tracking viral antigens during influenza infection in vivo.

C57BL/6 mice were infected intranasally with 10⁶ PFUs of NS1-GFP virus. (A) Six hours post infection (p.i.), GFP levels were assessed by flow cytometry in CD45⁺ lung cells: MHCII^hiCD11c⁺CD103⁺ DC (gate 2), MHCII^hiCD11c⁺CD11b⁺ DC (gate 2), SSC^hiMHCII^loCD11c⁺CD103^–macrophages (gate 1), and epithelial CD45^– cells. Lower panels show a representative percentage of GFP⁺ cells gated among each lung population. Graph represents the percentage of GFP⁺ cells among live lung cells. (B) Images show GFP expression in lung sections 6 hours after infection stained with anti-langerin and anti-CD169 Abs and analyzed by confocal microscopy. White arrows show CD169⁺ macrophage and langerin⁺ DCs. Original magnification, ×40, zoom 6. (C) Percentage of total DCs (left panel) or GFP⁺ DCs (right panel) among live lung cells at the indicated time points after infection (n = 3). (D) Representative dot plots showing the percentage of each DC population in the lung 48 hours after infection (left panel) and the percentage of GFP⁺ cells in each lung DC subset (middle and right panels). (E) Dot plots show the percentage of GFP expression in each MLN DC subset 48 hours after infection. Gating strategy is described in Supplemental Figure 1F. (F) Absolute numbers of total DC subsets (lower panel) or GFP⁺ DC subsets (upper panel) in the MLNs at the indicated time points after NS1-GFP infection. (G) Images show GFP expression in MLN sections isolated 48 hours after infection, stained with anti-langerin and anti-CD169 mAbs, and analyzed by confocal microscopy. White arrows show CD169⁺ subcapsular macrophage and langerin⁺ DCs. Original magnification ×40, zoom 6.