Figure 3.

Vaccine induced delayed type hypersensitivity in calf groups. Intradermal skin test performed on calves at 2 months post vaccination (A), and 12 months post challenge (B). Each graph shows the difference of pre injection skin thickness measurement (0 h) from the skin thickness measurement 72 h after purified protein derivatives (PPD) injection. Each data point represents an individual animal, while the horizontal lines indicate the mean value for each group with error bars representing the standard deviation; * p < 0.05 compared to the PBS group. The 0 h skin thickness was subtracted from the 72-h skin thickness prior to statistical analysis.