<p>(A) Viral titers in nasal wash samples of infected guinea pigs are plotted on days 2 and 4 p.i. On day 2 p.i., titers of the wild-type virus were significantly different from rPan99 627E (p = 0.0020) and from rPan99 627E 701N (p = 0.0057). On day 4 p.i., titers of the wild-type virus were not significantly different from those of either PB2 mutant virus (p≥0.03). (B) Titers of virus recovered from the supernatant of homogenized lung tissue at 2 d and 4 d p.i. Virus in three tissue samples from each of two animals was quantified; titers from one guinea pig are shown with open squares and titers from the second guinea pig are shown with closed diamonds. Titers of the wild-type virus were not significantly different from rPan99 627E (p = 0.39 on day 2 and p = 0.011 on day 4) or from rPan99 627E 701N (p = 0.067 on day 2 and p = 0.025 on day 4). All p-values were determined by Student's t-test. * indicates a significant difference relative to the wild-type, with p<0.01 as determined by Student's t-test. The mean and standard deviation for each data set are shown above the corresponding data points.</p
