FIG. 5.
IR2 to IR5 are not accessible to antibody at the surface of spirochetes. B. garinii strain IP90 spirochetes either were fixed with acetone or left unfixed. Unfixed spirochetes were resuspended in PBS containing preimmune or immune rabbit antipeptide antiserum or positive control mouse antiserum, while fixed spirochetes were incubated in PBS-human serum supplemented with the same antiserum samples. Sensitized spirochetes were probed with goat anti-rabbit or -mouse IgG–fluorescein conjugate.