Fig. 4
Cross-protection against P. multocida serotypes induced by live Δfis. Scheme of immunization and infection A. Serum IgG antibody titers B. The survival rates of mice subcutaneously immunized with live Δfis and PBS emulsifier and challenged with PmCQ2 (C) and PmB (D), respectively. Serum IgG antibody titers of PmCQ2 and PmB were monitored 7–90 days after immunization with live Δfis E. Scheme of immunization and antibody titer monitoring F. All data are expressed as mean ± SD. * P < 0.05; ** P < 0.01; *** P < 0.001; ns means no significant