Fig. 1 a Effect of blockade of the LTβR signaling pathway on FDC status and PrP labeling in the spleen. C57BL mice were treated with a single intraperitoneal injection of 100 µg hu-Ig (control) or 100 µg LTβR–Ig (above photos, times (‘dpi’) relative to scrapie challenge). Spleens were obtained 72 h later and frozen sections were stained for FDCs with the FDC-specific monoclonal antibody FDC-M2 (ref. 9; red) and for PrP with the PrP-specific polyclonal antiserum 1B3 (ref. 10; red). Original magnification,× 400. b and c Blockade of the LTβR signaling pathway significantly extends the incubation period of disease after peripheral infection with the ME7 scrapie strain. Mice were injected intracerebrally (b) or intraperitoneally (c) with a 1% brain ho-a b c