FIG. 4.

Serum antibody levels after immunization of C3H/HeN mice with plasmids encoding cell-associated (AgD or CgD) or secreted (SgD) antigens. Experimental groups consisted of 10 mice and included a null plasmid control group and a subunit gD vaccine group. Mice 6 to 7 weeks of age were immunized in each quadriceps muscle mass with 50 μg of DNA (total of 100 μg) or subcutaneously with 400 ng of affinity-purified rtgD in 100 μl of VSA3 plus HBSS. All mice were given a booster injection at 2 weeks after initial immunization with the same dose. Serum ELISA titers were determined as described for Fig. 3. Plasmid construct or subunit gD designations are indicated in the top center of each graph. Each symbol represents a single mouse. The horizontal line in each column represents the mean antibody titer for the group.