CD226 and infection: As shown in Figure 1, the phenotypically “aggressive” P15- and “moderate” P4-infected HFFs showed enhanced levels of the DNAM-1/CD226 ligand poliovirus receptor (PVR/CD155) mRNA at 48 but not 24 hours post infection (hpi) in comparison with Merlin- or mock-infected cells, while infection with P6, P10, and P14 did not lead to significant changes in PVR/CD155 expression at either time point (Figure 1A).