BHK cell monolayers were transfected with infectious clone (D2/IC) RNAs containing a WT cHP sequence and mutations predicted to disrupt (HP3.4) and restore (HP11.9) cHP basepairing. Viral titer was assessed at 24, 48, 72, 96 and 120 hours post-transfection and normalized for transfection efficiency as determined by qRT-PCR at 2 hours post-transfection. (A) Schematic diagram of pD2/IC and pD2/IC-HP3.4 and pD2/IC-HP11.9 variants. (B) Kinetics of viral replication in BHK cells. In experiments where HP3.4 virus was below the limit of detection, titer was recorded as the limit of detection, 1.06 LOG10 PFU/ml. Data represent an average of at least 3 experiments, and error bars indicate SD. *, p < 0.002 relative to WT by Wilcoxon rank sum test.