Fig. 3. Arithmetic means of serum virus neutralizing antibody titers of calves vaccinated with 6 PD50 vaccine. (A) 6 PD50 single < 1.50, (B) 6 PD50 single 1.50–1.80, (C) 6 PD50 single > 1.80, (D) 6 PD50 booster < 1.50, (E) 6 PD50 booster 1.50–1.80, (F) 6 PD50 booster > 1.80. Arrows indicate the time of vaccination. Serum samples were collected before vaccination as day 0 and additional blood samples were obtained on days 28, 60, 90, and 120 postvaccination and analyzed via virus neutralization test. Horizontal red lines indicate the cut-off level of antibody titers for estimated protection.
