FIG 4.

Upregulation of IFN-β and TNF-α gene expression in IBDV-infected HeLa cells upon IFN treatment is dependent on PKR expression. HeLa control and HeLa PKR-silenced cells were infected with IBDV (MOI of 2) and treated or not with 1,000 IU/ml of hIFN-α at 3 h p.i. Mock-infected (M and M+3) and IBDV-infected (I and I+3) cells were harvested at 24 h p.i. and subjected to RNA extraction. The expression levels of the selected genes, as indicated, were determined by SYBR green-based RT-qPCR. The expression level of each cellular target gene was normalized to the HPRT mRNA content and is presented on a log₁₀ scale as the fold change over the level in mock-infected HeLa silencing control or HeLa PKR-silenced cells. Bars indicate means ± standard deviations based on data for triplicate samples. Dotted bars, mock-infected cell samples treated with IFN; striped bars, infected cell samples not treated with IFN; solid bars, infected cell samples treated with IFN. *, **, and *** indicate P values of <0.05, <0.01, and <0.001, respectively, as determined by unpaired Student's t test. ns, not significant.