(A) Survival curve for mice infected with influenza A/PR/8/34 that were given bone marrow transplant with MeCP2^Tg3 or wild-type bone marrow. n = 28 for WT→WT, n = 23 for Tg3→WT, n = 16 for WT→Tg3, and n = 18 for Tg3→Tg3. ***P < 0.001 by log-rank (Mantel-Cox) test. ns, not significant. (B) Flow cytometry of RBCs in bronchoalveolar lavage (BAL) fluid on day 5 post infection (p.i.). Mock infected, n = 4 wild type and 3 MeCP2^Tg3. Day-5 infected, n = 7 wild type and 4 MeCP2^Tg3. Quantification on right shows percentage of cells expressing the erythroid marker Ter119 (mean ± SEM). ***P < 0.001 by 2-way ANOVA with Bonferroni post test. (C) Gross appearance of wild-type and MeCP2^Tg3 lungs on day 7 p.i. (D) Images and quantification of Evans Blue dye (EBD) in BAL fluid taken from uninfected, day 5 p.i., and day 7 p.i. Mice were injected with EBD 1 hour prior to harvest. For day 0, n = 3 wild type and 3 MeCP2^Tg3. For day-5 infected, n = 3 wild type and 4 MeCP2^Tg3. For day-7 infected, n = 5 wild type and 4 MeCP2^Tg3. Mean ± SEM. **P < 0.01 by 2-way ANOVA with Bonferroni post test. (E) Gross appearance of lungs from mice given EBD and analyzed 1 hour later. Lungs were perfused to remove remaining vascular dye and blood, and BAL fluid was taken. Images are representative of n = 3 mice per group for uninfected, and n = 4 mice per group for day 7 p.i. (F) Total BAL cell counts (mean ± SEM) on day 3 and day 8 p.i. n = 3 mice per group. **P < 0.01 by 2-way ANOVA with Bonferroni post test. ns, not significant. (G) Resistance, compliance, and pulmonary artery pressure measured on day 8 p.i. n = 5 for wild type and 3 for MeCP2^Tg3; mean ± SEM. **P = 0.0074 by 2-tailed Student’s t test. (H) H&E staining of day 7 p.i. lungs that were not perfused or inflated demonstrates both arterial narrowing and perivascular edema (black arrowheads, pulmonary arteries). Representative of 2 experiments with at least n = 3 mice per group. Scale bar: 200 μm for large images, and 50 μm for insets.