Multiple-cycle viral yield assays. In order to complement the information provided by the plaque assay, namely the plaque velocity, we also conducted multiple-cycle viral yield experiments. The results of these experiments for the WT and H275Y mutant strains are shown in Figure 3 . The kinetics of the viral yield experiments can be broken into two different phases: an exponential growth of virus concentration, characterized by the viral titer growth rate, followed by an exponential decay of virus concentration, characterized by the viral titer decay rate, after the viral titer peak. The viral titer decay rate was the same for both strains at 0:19+0:02h {1 .