Figure 2. CJ2-gD2 is significantly more effective than gD2-alum/MPL subunit vaccine in eliciting an HSV-2-specific neutralizing antibody response in immunized guinea pigs.

A. Female Hartley guinea pigs were randomly assigned to three groups of eight animals each in the first experiment and three groups of six to eight each in the second experiment. They were either sham-immunized with DMEM (n = 8, 8), immunized with 3 µg of purified recombinant gD2 freshly formulated with 7.5 µg of MPL and 75 µg of alum (n = 8, 6) or immunized with CJ2-gD2 (n = 8, 6) at a dose of 5×10⁶ PFU on days 0, 14, and 28. Blood was taken after the first, second, and third immunizations as detailed in the Materials and Methods. Heat inactivated serum from each animal was assayed individually for HSV-2-specific neutralizing antibody titers on Vero cell monolayers. The results represent average titers ± SEM. B and C. Western blot analysis with serum prepared from CJ2-gD2 (B)- and gD2-alum/MPL (C)-immunized guinea pigs as detailed in the Materials and Methods. Lanes 1, 2, and 3 represent cell extracts prepared from mock-infected Vero cells, HSV-2-infected Vero cells, and gD2-transfected U2OS cells, respectively.