(A) Plaque assays performed with indicated virus on MDCK cells. (B) Quantification of plaque diameter from 34–64 individual plaques per virus identified from 2–3 independent experiments. *p < 0.05. No conditions were statistically significant compared to rUd M2-WT. Low MOI multistep growth curves performed on (C) MDCK cells or (D) hNECs with the indicated viruses at 32°C. Data are pooled from two independent replicates each with n = 3 wells per virus (total n = 6 wells per virus). *p < 0.05 compared to rUd M2-WT (two-way ANOVA with Dunnett’s posttest). In (C) no time points were significantly different while in (D) rUd M2-A83M (48, 72, 96, and 120 HPI), rUd M2-A83K (24, 36, and 48 HPI) showed differences. Dotted line indicates limit of detection.