MA NS1 mutants M106I+L98S and D125G temporally increase cytoplasmic NS1 localization in infected mouse cells.

<p>Mouse M1 cells were infected at MOI = 3 with the rHK NS mutant viruses, the HK-wt virus, or prototype mouse-adapted viruses A/PR/8/34 (H1N1) (PR8) or A/WSN/33 (H1N1) (WSN). Following 4, 8, 16, and 24 hpi, cells were fixed and stained using a polyclonal anti-NS1 antibody and Cy3-conjugated secondary as well as DAPI to localize the nucleus. (A) Representative images are shown, taken at 63× using oil immersion. (B) Data represent the average percentage of cells positive for the NS1 antigen detected in the cytoplasm ± SD (analysis of n = 5 randomly selected images) for 4–24 hpi (*p<0.05, ***p<0.001, ****p<0.0001, *****p<0.00001; two-tailed student’s t-test compared to HK-wt values).