Fig. 5.

SadA induces an antibody response in mice. (A) Experimental design of challenge experiment. (B) Numbers of CFU recovered from the livers and spleens of mice 2 days after challenge. Mice dosed with SadA-Alum had lower levels of S. enterica in both the spleen and liver than the control, whereas mice dosed with SadA only had lower bacterial numbers in the liver. (C) Sera taken from mice prior to challenge with S. enterica SL1344 were tested for relative amounts of SadA-specific IgG. SadA-specific IgG was found in mice dosed with SadA and SadA-Alum. (D) SadA-specific IgM was found in serum from PBS control mice collected postchallenge but not in serum collected prechallenge, indicating SadA expression in vivo during S. enterica SL1344 infection. (E) Numbers of CFU recovered from the spleens of mice infected with opsonized S. enterica SL1344. Bacteria opsonized with the serum from SadA-immunized mice had a reduction in bacterial numbers compared to bacteria opsonized with the PBS control serum.