Figure 6.

Cleaved caspase-3 is found in infected areas of the lungs suggesting host cells are undergoing apoptosis. Left lower lobe sections of lungs harvested 1 hour (A and E), 24 hours (B and F), or 48 hours (C, D, G, and H) after infection were perfused in 10% formalin followed by immunohistochemistry with antibodies to cleaved caspase-3. C and G: In moderate lesions, caspase-3 staining appears limited to the periphery of the lesion. D and H: More intense staining and higher background were found in congested areas. Images are representative of lesions found in the tissues. Original magnifications: ×100 (A–D); ×400 (E–H).