IgG titers in mice injected with vaccines with different types of aluminium-containing adjuvants. Mice (n = 8/group) were injected twice with WCA (107 cells/dose) alone or combined with four different aluminum-containing adjuvants. The IgG titer in serum was determined two weeks after the second injection. The symbols represent individual mice and the horizontal line indicates the geometric mean. The geometric means of groups with different letters are different at p < 0.05.