FIG 6.

HSV-1 replication in IE1-expressing or IE1-negative cell lines. (A and B) Growth curve assays. U-251 MG (or HELF) or U-251 MG-IE1 (or HELF-IE1) cells were infected with WT HSV-1 (strain 17) (A) or FXE strain (ICP0 RING finger helix mutation) (B) at an MOI of 0.01. The cells and supernatant samples were collected at the time points indicated. PFU assay was performed to count the viral particle numbers. Viral growth curves were determined. A Student's t test was applied to perform the comparison between two groups. Significance was set at a P value of <0.001 (*). (C and D) Western blot assays. The cells were infected with HSV-1 at an MOI of 0.01 for different times as shown. The whole-cell lysates were used for Western blot assays to examine the proteins as indicated. The ICP0 band was first compared to tubulin for normalization, and then the normalized ICP0 levels were compared between the non-IE1-expressing cells and the IE1-expressing cells. The ratios are shown under each group. Significance was set at a P value of <0.001 (*). Statistical analysis was carried out using pairwise two-tailed t test to compare the two groups (IE1-expressing cells versus non-IE1 cells) and the differences were significant, as shown by an asterisk (P < 0.001).