Figure 2.

Glycoprotein D (gD)-specific antibody isotypes in mice immunized with pgD (plasmid vector pCAN1 expressing the full-length glycoprotein D protein from bovine herpesvirus type 1 under the cytomegalovirus promoter). Toll-like receptor 9 (TLR9)^–/– and TLR^+/+ mice were immunized with pgD (at doses of 0·1 µg, 1 µg or 10 µg) or gD protein (1 µg) plus CpG 1826 (10 µg). Primary immunization was on day 1 and the secondary immunization was 4 weeks later. Two weeks after the secondary immunization, mouse sera were assessed for gD-specific immunoglobulin G (IgG)1 and IgG2a titres by enzyme-linked immunosorbent assay (ELISA). Data presented are values for individual mice and the bar represents the group mean (n = 5). P < 0·001: TLR9^–/– and TLR^+/+ mice versus control for both IgG1 and IgG2a by one-way analysis of variance (anova) followed by Tukey's multiple comparison test. P < 0·05: IgG2a titre. P < 0·01: IgG1/IgG2a ratio by t-test comparing gD protein with CpG oligonucleotide (ODN)-immunized TLR9^–/– mice versus gD protein with CpG ODN-immunized TLR9^+/+ mice. Unvaccinated control mice remained negative (titre < 1). There were no significant differences in antibody titres between TLR9^–/– and TLR^+/+ mice.