FIG. 5.

Serum ELISA titers of antigen (Ag)-specific total IgG (A) and antigen-specific IgG1 and IgG2a (B) antibodies following immunization with the indicated proteins. Groups of 6-week-old CBA/Ca mice were vaccinated s.c. at days 0 and 28 with 25 μg of the respective protein vaccine mixed in a 1:1 ratio with alum adjuvant. Mice were bled from the tail at days (d) 21 and 42 before bacterial challenge on day 56. Sera were analyzed by ELISAs, and the end-point titers were determined. The values represent the mean ± standard error of the mean for 12 mice.