FIG. 4.
Antibody response to ZZ-DTR, ZZ-DT168–220, and Dtx in Blanc de Bouscat rabbits. The rabbits were immunized with either Freund’s adjuvant or aluminum hydroxide (Alum). Blood samples were collected, and sera were serially diluted in 0.1 M Tris buffer–0.1% caseine (pH 7.4) and incubated overnight at 4°C on DT-coated microtiter ELISA plates. Antibody binding was revealed with a goat anti-rabbit–PhoA conjugate. Titers are defined as the highest serum dilution that led to an absorbance of 0.6 at 414 nm in 1 h. Each dot represents the titer obtained for one rabbit.