FMDV-specific immune responses in cattle. Groups of cattle (n = 5) immunized with one dose, 1/3 dose, 1/9 dose of FMD VLP, including two healthy cattle as the control, by intramuscular injection. Blood samples were collected at 9 dpi, 16 dpi, 21 dpi and 2 dpc, 5 dpc, 10 dpc for virus-specific antibody response (A) and neutralizing antibody response (B). The titers of virus-specific antibody and neutralizing antibody were expressed by the average titer of cattle in one whole group at different time points. PMBC were isolated from all cattle at 21 dpi. IFN-γ secretion (C) by PMBC was measured and shown as pg/mL. Statistical significance among groups was compared.