Short-term treatment with ruxolitinib (Ruxo) promotes long-term survival of LCMV-infected Prf1^−/−mice. (A) Naive and LCMV-infected Prf1^−/− mice were left untreated (UnRx) or were treated with αIFN-γ on days 4 and 7 postinfection or with Ruxo on days 4 to 8 postinfection. αIFN-γ and Ruxo were discontinued on day 9, and survival was monitored until day 35. Data are combined from 3 independent experiments. P < .0001, log-rank test. (B) Mice were treated as in (A) and euthanized on day 20. For comparison, untreated LCMV-infected mice were euthanized and analyzed on day 9 (UnRx). Blood was analyzed for platelet count (PLT) (B) and for red blood cell count (RBC) and hemoglobin (Hb) (C). (D) Levels of serum cytokines. (E) Frequency (left panel) and total numbers (right panel) of splenic neutrophils on day 20 postinfection. Each data point represents 1 mouse. Data (mean ± standard deviation) are combined from 2 independent experiments. The total number of mice per group was n = 6 each (Naive and UnRx), n = 7 (αIFN-γ) and n = 8 (Ruxo). (F) Percentage survival of Naive and LCMV-infected Prf1^−/− mice left untreated (UnRx) or treated with αIFN-γ, Ruxo, neutrophil-depleting antibody (αNeut), or a combination of αNeut and αIFN-γ from days 4 to 8 postinfection, followed by treatment discontinuation. Survival was followed to day 35. Data (mean ± standard deviation) are combined from 2 independent experiments. P < .0004, log-rank test. Total number of mice examined was n = 6 each (Naive, αIFN-γ, and Ruxo), n = 3 (UnRx), and n = 9 each (αNeut and αNeut+αIFN-γ). *P < .05, **P < .01, ***P < .001, **** P < .0001.