Interferon-? Inhibits Ebola Virus Infection

Rhein, Bethany A.; Powers, Linda S.; Rogers, Kai; Anantpadma, Manu; Singh, Brajesh K.; Sakurai, Yasuteru; Bair, Thomas; Miller-Hunt, Catherine; Sinn, Patrick; Davey, Robert A.; Monick, Martha M.; Maury, Wendy

Statistical analyses were performed using GraphPad Prism software (GraphPad Software, Inc.). Results are shown as means ± standard error of the means (s.e.m.). Two-tailed, unpaired Student's t-tests were used to compare experimental treatment group to no IFNγ control for the majority of the studies reported here. To assess variance in these studies, F tests to compare variance were performed in parallel to determine that variance was similar between groups. For protein translation inhibition studies, a one-way analysis of variance (ANOVA) was performed to compare the no IFNγ control to the different treatments followed by a Tukey post hoc multiple comparison analysis to determine statistical significance. For nonparametric data, Mann-Whitney U-test was used. Log-rank (Mantel-Cox) tests were used to analyze differences in survival. P values less than 0.05 were considered significant. Death of mice at a particular day is indicated by a cross and value indicating the number of mice that succumb to infection. (B) IFNγ enhances survival of EBOV GP/rVSV infected mice and more modestly enhances survival following wild-type VSV infection. 3.3 μg IFNγ or PBS was administered by i.p. injection to BALB/c IFNAR -/mice 24 hours prior to or 2 hours following 10 3 iu of EBOV GP/rVSV or 10 2 iu VSV infection (n!8/treatment). Protection studies with 3.3 μg of IFNγ were also performed at 6 hours following EBOV GP/rVSV challenge. Significance was determined by Mantel-Cox Test; compared to EBOV GP/rVSV PBS mice, ÃÃ p< 0.01, ÃÃÃ p < 0.001, compared to VSV PBS mice, # p< 0.05, ### p< 0.001, compared EBOV GP/rVSV IFNγ treated groups to VSV IFNγ treated groups, @ p< 0.05. (C) Treatment of mice with 10 μg IFNγ 24 hours prior to or 2, 6, 12 or 48 hours following EBOV GP/rVSV infection prevents weight loss during the first 3 days of EBOV GP/rVSV in vivo infection. (D) IFNγ (10 μg) treatment protects against weight loss at early days following infection. IFNγ was given 24 hours prior or 2, 6, 12 or 48 hours following EBOV GP/rVSV. For C and D, results represent means ± s.e.m. For B-D, treatment groups consist of at least 8 mice per group. Significance was determined by Student's t-test compared to PBS control, ÃÃÃ p < 0.001. Findings in panels A-C represent 7 mice per group from one experiment. (D) IFNγ treatment inhibits MA-EBOV viremia. Serum was collected 4 days following infection and viral loads quantified with 10-fold serial dilutions of serum on Vero-E6 cells to determine PFU/mL. Data represent 2 or 3 mice per group. Significance was determined by Student's t-test compared to PBS control, Ã p < 0.05. (TIF) S1 Table. IFNγ stimulated genes significantly altered in human MDMs treated with 20 ng/ ml of IFNγ as assessed by gene array analysis. ISGs that were assessed further in this study are bolded. (XLSX) S2 Table. IFNγ stimulated genes significantly altered in human alveolar macrophages treated with 20 ng/ml of IFNγ as assessed by gene array analysis. ISGs that were assessed further in this study are bolded. (XLSX)