FIG 4.

Dynamic relationship between level of anti-P. acnes antibody and survival rates. Based on the different IgG titers at the indicated time points, all mice immunized with P. acnes with astragalus polysaccharide adjuvant were divided into eight groups (group 1, PBS control group, solid triangles; group 2, astragalus polysaccharide control group, solid circles; group 3, IgG titer of <100 at day 35, crosses; group 4, IgG titer of 400, open triangles; group 5, IgG titer of 800, open circles; group 6, IgG titer of 1,600, squares; group 7, IgG titer of 3,200, diamonds; group 8, IgG titer of 6,400, stars). Selected mice in each group were challenged with A. pleuropneumoniae serotype 1 (5× LD₅₀). The survival rates of all groups were calculated at day 7 postchallenge. There were no significant differences among groups 3 to 8 (P > 0.05). Also, the survival rates of groups 3 to 8 were significantly higher than those of control groups 1 and 2. *, P < 0.05; **, P < 0.01; #, P > 0.05.