HIF1A and infection: As can be seen in Figures 6B and 6C, the HRE reporter gene results of infected HFF (Figure 6B) and U251 (Figure 6C) cells indicate that HCMV Titan WT infection induces HIF-1 transcriptional activity to a great extent, which is partially, but significantly reduced in cells infected with the Titan ΔUS28 strain.