Hepatitis E virus persists in the presence of a type III interferon response
Fig 2
Type III IFN response regulates HEV replication.
(A) Immunoblots of IFNAR1, IFNLR1 and β-actin in HepG2 cells transduced with lentiviruses expressing gene-specific shRNA or GFP (Ctrl). (B) ISRE promoter activity in different cells after IFN-α or IFN-λ treatment. HepG2 cells were transfected with an interferon-sensitive response element (ISRE) promoter-driven firefly luciferase reporter plasmid ISRE-Luc and a herpes simplex virus thymidine kinase promoter-driven Renilla luciferase (TK-RLuc) plasmid for 24 h, then treated with IFN-α (100ng/ml) or IFN-λ1 (220ng/ml) for 24 h. Data are expressed as fold changes relative to non-treated cells based on the relative luciferase activities (firefly luciferase vs. Renilla luciferase). Shown are representative results (mean ± SEM) from two independent experiments each performed in triplicate. (C-E) Effects of IFN receptor knockdown on ISG expression and HEV replication. HepG2 cells transduced with lentiviruses expressing gene-specific shRNA or GFP (Ctrl) were infected with HEV for 5 days. (C) Intracellular IFIT1 mRNA expression determined by qRT-PCR. Results are represented as fold changes relative to HEV-infected control cells. (D) HEV RNA abundance determined by qRT-PCR (fold changes relative to HEV-infected control cells). (E) Cells expressing different shRNA or GFP (Ctrl) were infected with HEV for 5 days, harvested and subjected to three rounds of freeze-thaws prior to inoculation to naïve HepG2 cells. Infected cells were detected by IFA and HEV foci were counted after 5 days. Each data point represents the mean ± SEM of at least 2 independent experiments in duplicate each. * P<0.05; ** P<0.01.