Comparison of the immune responses to ACAM529 and gD in mice.

<p>Groups of 60 female BALB/c mice received either two doses given three weeks apart of 10⁶ PFU of ACAM529, or three doses given two weeks apart of gD (2 µg adjuvanted with CpG and alum), or PBS, all given IM. The last dose was received on the same day for all groups. Serum was collected nine days after the last dose. (A) Plaque reduction neutralization titer (50% PRNT) in the presence of complement. The vaccine groups are significantly higher than PBS and not significantly different from each other (one way ANOVA). (B) Total IgG ELISA against HSV-2 lysate. All 3 groups are significantly different from each other (* P<0.05; one way ANOVA). (C) IgG endpoint titers determined by ELISA against purified recombinant gD for mice immunized with ACAM529 or gD. Immunization with gD gave significantly higher anti-gD titers than immunization with ACAM529 (*** P<0.0001; two-tailed t test). (D) In parallel with the larger groups of mice discussed above, three groups of six mice were immunized in the same way and their spleens harvested 9 days after the last vaccine dose. Splenocytes were cultured in the presence of the I-A^d-restricted CD4+ T cell epitope represented by gD-2 peptide 245–259, and HSV-specific CD4+ T cell responses were quantitated based on the frequency of interferon-γ-secreting cells following stimulation. The indicated values represent the mean for each group calculated based on triplicate measurements made for each splenocyte sample and error bars indicate the standard error for the group. ACAM529 is significantly different from both the gD and PBS groups (* P<0.05; one way ANOVA). The dotted line indicates the detection limit in (A) and (B) above.