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. 2009 Jun 3;83(16):8233–8246. doi: 10.1128/JVI.02672-08

FIG. 8.

FIG. 8.

Influenza A virus NP exhibits increased nuclear retention in Bax KO cells. Nuclear retention of NP due to a lack of caspase activity has been linked to decreased titers of virus. DAPI staining was used for nuclear localization (A, E, I, and M), lysosomes were stained with LysoTracker Red DND-99 (B, F, J, and N), and influenza A virus NP localization was determined using an NP-specific antibody (C, G, K, and O). Images were taken using a confocal microscope. (D, H, L, and P) Merge. Lysosomal localization of influenza A virus NP was not observed in WT cells or any of the KO cells. NP showed near-complete cytoplasmic localization in WT cells (D) and Bax/Bak DKO cells (P). A slight nuclear retention of NP was observed in Bak KO cells (L), while in Bax KO cells (H), a nuclear retention of influenza A virus NP is obvious in all infected cells. Bars, 10 μm. (Q) Nuclear retention of NP in infected Bax KO and, to a lesser extent, Bak KO cells was confirmed by Western blotting of cytoplasmic (C) and nuclear (N) fractions of infected cells. (R) β-Tubulin was used to ensure efficient fractionation.