Fig. 6.

Effects of testosterone-replacement on the outcome of ma2009 virus infection in aged male mice. Aged male mice were either treated with placebo (P) or time-release testosterone capsules (T) for 1 wk prior to inoculation with IAV (ma2009). A: concentrations of testosterone were measured in serum samples collected 21 days dpi (n = 9–10/treatment). Following intranasal inoculation with IAV, body mass (B), clinical disease (C), and survival (D) were monitored for 21 dpi (n = 24–34). Titers of infectious virus were measured 3, 7, 14, or 21 dpi (E; n = 4–8/treatment/time point). Lung tissue was collected from mock-infected and IAV-infected aged mice that were treated with placebo or testosterone and euthanized 7, 14, or 21 days dpi (n = 5–10/treatment/time point). Lung tissue sections were scored for markers of inflammation, and cumulative inflammation scores are presented (F). *Significant difference between testosterone-treated and placebo-treated aged male mice (P < 0.05).