Figure 1.

M1 and the Vβ4⁺ CD8 T cell response are required for virus-induced inflammation and fibrosis in IFNγ-unresponsive mice. IFNγR^−/− mice were infected with 10³ PFU of the indicated virus intranasally and analyzed at 28 d after infection in A–D. (A) Hematoxylin and eosin staining of pathological changes in the spleen, liver, and lung. Bars: (spleen and liver) black, 200 μm; (spleen and liver) white, 80 μm; (lung) black, 400 μm; (lung) white, 40 μm. (B) Representative flow cytometric plots of Vβ4⁺ CD8⁺ T cell populations from mice infected with each virus. Numeric values are given for the proportion of CD8⁺ cells (right quadrants only). (C) Immunohistochemical staining for CD8⁺ cells and Vβ4⁺ cells in inflammatory lesions of the lung from M1.MR-infected animals, as indicated by brown chromogen deposition. Bars, 160 μm. (D) Persistent replication of each virus from each organ as measured by plaque assay. (E) Masson trichrome staining of lung sections at 180 d after infection from mice infected with 10⁵ PFU of WT or M1Δ511 virus. Blue indicates areas of collagen deposition. Bars, 200 μm.