Fig. 3.

Localization of B. anthracis spore proteins within the spore by immunoelectron microscopy. Spores were labeled with immunogold by incubation with affinity-purified anti-spore protein polyclonal IgG followed by a gold-labeled secondary antibody. Labeling occurred either before or following embedding in 4% formaldehyde in PBS (pH 7.0) for a minimum of 8 h as described in Section 2.