FIG 7.

GTV and HRTV infection activate three branches of the UPR. (A) HEK 293 cells were infected by GTV, HRTV, or SFTSV, and then, at the indicated time intervals, the cells were fixed, and the intracellular level of NP was monitored by using immunofluorescence. (B) The supernatants of infected cells were also collected, and viral titers were measured by determining the TCID₅₀. All experiments were performed at least three times, and values represent means ± the SDs from three replicates. ***, P < 0.001 (Fisher LSD tests). GTV (C)- or HRTV (E)-infected HEK 293 cells were collected at the indicated time intervals, and total proteins were extracted and subjected to Western blot analyses for GRP78, ATF6 p90, phos-eIF2α (Ser51), total eIF2α, Gn, NP, and the internal control actin. Anti-SFTSV Gn (anti-Gn) and anti-HRTV NP (anti-HNP) were used to detect GTV GP and HRTV NP, respectively. (D and F) RNA samples from the cells described above were also analyzed for spliced XBP1 mRNA by using reverse transcription-PCR. The intensity of protein band was measured by ImageJ_v1.8.0. For each time point, the protein intensity was first normalized to actin and then normalized to the corresponding mock-treated group.