Figure 1.

IgG antibody titers against P. multocida after vaccination. Blood samples were collected before each immunization (days 0 and 21) and before challenge (day 35). ‘C44-1 vaccine’ indicates mice inoculated with the inactivated Alh–C44-1 vaccine on days 21 and 35. ‘EO630 vaccine’ indicates mice inoculated with the live EO630 vaccine on days 21 and 35. ‘PBS control’ indicates mice inoculated with sterile PBS buffer on days 21 and 35. The P. multocida-specific antibody titers in the experimental and control groups were measured with an indirect ELISA and recorded at OD₄₅₀. The error bars represent the SE. ** p < 0.01; * p < 0.05; ns, not significant.