Figure 3.

Comparative photomicrograph of tissue sections from BTV-4- infected and control animals. H&E, 100X. IFNAR(-/-) mice (n = 3) were infected subcutaneosuly with 10³ PFU of BTV-4. Representative pictures of tissues from the spleen, thymus, and lung collected at 72 h.p.i. and stained with hematoxylin and eosin, are shown. Extensive necrosis and lymphoid depletion, mainly located in the marginal zone bordering the white pulp (asterisk), was detected in the spleen from BTV-infected specimens, as well as a population of neutrophils and macrophages invading necrotic tissue. The thymus of BTV-infected animals showed extensive necrosis and lymphoid depletion (asterisk), with loss of the boundaries between the medulla (M) and the cortex (C). In the lungs of BTV-infected animals a diffuse interstitial pneumonia was encountered, showing multifocal atelectasis and increased septum size (arrows), with infiltration of mononuclear cells and scarce neutrophils.