Fig. 4

Proliferation of PBMCs. PBMCs were isolated from chickens vaccinated intramuscularly at 2 weeks after second and third inoculations, and the cellular immune response was assessed by monitoring cell proliferation. Stimulation index (SI) was calculated based on cell proliferation, as determined using the ELISA-BrdU assay and the following equation: SI = (OD450 − OD690 of antigen-treated cells)/(OD450 − OD690 of untreated cells). Data are presented as the mean ± standard error of the mean. Statistical significance of differences is illustrated as follows: *P < 0.05, **P < 0.01