FIG 3.
Assessment of the virulence of P. multocida in mice. (A) Confirmation of C48-ΔPmorf0222 mutant strain by Western blot analysis. The whole protein of the C48-1 wild-type strain (lane 1), C48-ΔPmorf0222 mutant strain (lane 2), and C48-ΔPmorf0222C complemented strain (lane 3) was detected with anti-rPM0222 sera. (B) SDS-PAGE analysis of the outer membrane vesicles (OMVs) of P. multocida. Isolation of OMVs from wild-type strain (lane 1) and mutant strain (lane 2). (C) Total proteins of OMVs extracted from the wild-type strain and mutant strain reacted with the anti-rPM0222 sera as demonstrated by Western blot analysis. Isolation of OMVs from wild-type strain (lane 1) and mutant strain (lane 2). (D) Survival rates of each group of mice (n = 7) exposed to the wild-type strain, mutant strain, or complemented strain and sterile PBS (200 μL). (E and F) The bacterial load in each group of mice (n = 10) infected with the wild-type strain, mutant strain, or complemented strain in the liver (E) and spleen (F) 6 h postinfection. **, P < 0.01; ***, P < 0.001.