Multifunctional Adaptive NS1 Mutations Are Selected upon Human Influenza Virus Evolution in the Mouse
Figure 9
Mouse-adapted NS1 mutations enhance virus protein synthesis in untreated and IFN-β primed mouse cells in vitro.
M1 cells were left untreated or were pre-treated with 200 U/mL murine IFN-β for 24 hours, then infected with rHK NS MA or HK-wt virus at an MOI of 2. At 2, 4, 6, and 8 hpi the cells were pulsed with 35S for one hour then lysate was collected in SDS buffer. Autoradiography of collected samples are shown for (A) full time courses of HK-wt and rHK NS M106I + L98S and (B) 8 hour time points of all NS mutants. (+) and (−) symbols indicate whether cells were pre-treated with IFN-β. NP, M1 and NS1 protein positions are indicated, and were verified by western blot (data not shown). Data shown are representative of two independent experiments, which were each subject to densitometry analysis. Data represent the means ± SE (*p<0.05, **p<0.01, *** p<0.001; two-tailed student's t-test) for NS1 and M1 protein band density relative to rHK-wt in untreated cells (C) and in IFN-β primed cells (D).