Figure 2.

ANP32B deficiency impairs influenza A virus replication in mice and in murine cells. (A–C) ANP32B^+/+ and ANP32B^−/− mice were either control treated with PBS or infected with 10³ pfu of a seasonal H3N2 subtype (A) or a highly pathogenic H5N1 human isolate (B). (A,B) Viral titers were determined 3 and 6 days p.i. in lung and brain of infected animals. No virus was detected in PBS infected mice (n = 5). Presented are individual organ titers for each animal as well as the means ± SD for each group (n = 5–6). (C) At 3 and 6 d p.i., lungs from infected animals were removed and immunohistochemically (IHC) stained for viral NP antigen. Additionally, hematoxylin and eosin (H/E) staining was performed. Shown are representative images for each group (n = 5). Scale bar represents 10 μm. Original magnification, 10x. (D,E) Viral titers in H3N2 or H5N1 infected murine lung fibroblasts deficient for ANP32B were determined by plaque test at the indicated time points (h p.i., hours post infection). (F) Knockout of ANP32B in murine lung fibroblasts was confirmed by Western blotting. (A–F) Statistical significance was calculated using the two-tailed Student's t-test (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001; ns, not significant).