FIGURE 6.

The activation of IRE1 pathway promotes CSFV replication. (A) PK-15 cells were pretreated with 4μ8c (0, 1, 5, and 10 μM) for 6 h then infected with CSFV containing the corresponding concentrations of 4μ8c. After 24 h post infection, samples were collected and viral titers and copies were detected as described above. The inhibiting effect of 4μ8C on the IRE1-XBP1 signal was analyzed by detecting the splicing level of XBP1 and the expression of GRP78. Error bars represent the mean ± SD of 2 independent experiments; one-way ANOVA test; ^∗P < 0.05, ^∗∗P < 0.01. (B) PK-15 cells were infected with CSFV, after 12 h post infection, BIX (0, 10, or 20 μM) was added to cell medium to up-regulate the expression of GP78, after 24 h post infection, samples were collected and viral titers and copies were detected as described above. Error bars represent the mean ± SD of 2 independent experiments; one-way ANOVA test; ^∗P < 0.05, ^∗∗P < 0.01. (C) PK-15 was transfected with the shGRP78 or shRNA-Scramble eukaryotic expression plasmid followed by CSFV infection. Samples were collected for viral titers and copies were detected as described above. Error bars represent the mean ± SD of 2 independent experiments; student’s t-test; ^∗P < 0.05. (D) PK-15 were transfected with the PEGFP- GRP78 or PEGFP-N1 eukaryotic expression plasmid followed by CSFV infection. After 24 h post-infection, samples were collected for viral titers, and copies were detected as described above. Error bars represent the mean ± SD of 2 independent experiments; student’s t-test; ^∗P < 0.05, ^∗∗P < 0.01.