Figure 3.

Indirect immunofluorescence assay of the sporulated B. subtilis RB and B. subtilis 168 strains. (A) Spores of B. subtilis 168 under and RB under 40×bright-field of fluorescence microscopy (B) Spores of B. subtilis 168 and RB under 40× fluorescence field, with different serum as primary antibodies and Cy3- conjugated goat anti-mouse IgG was used as secondary antibody. Only the spores of B. subtilis RB incubated with mouse-derived anti-PCV2 hyperimmune serum emit fluorescent signals in the fluorescent field.