Vaccination enhanced chlamydial clearance from the guinea pigs genital tract. Groups (n =5) of guinea pigs were immunized i.n. with rCPAF/CpG or CpG alone (mock) and boosted twice at two-week intervals. Another group (n = 5) of guinea pigs received one i.n. dose of live C. trachomatis serovar D EBs (CT-D; 1×105 IFUs). One month after the final immunization, guinea pigs were challenged i.vag. with 105 IFU CT-D. Chlamydial shedding was monitored every third day post challenge until day 36 and presented as mean ± SD for each group at each time point. * Significant reductions (p < 0.05; one-way ANOVA) in bacterial shedding by (a) bar graph and (b) overall area and (c) area under the curve between the indicated group and CpG-immunized (mock) guinea pigs are shown. (d) The number of guinea pigs shedding Chlamydia after genital challenge for each immunization group is summarized. (c) ** Significant reduction (p=0.002), ANOVA with Tukey B) between groups; (d) ** Significant reduction (p=0.006 and p=0.0001, respectively, Fisher’s exact test) in number of rCPAF+CpG and CT-D immunized animals, compared to CpG immunized animals, shedding chlamydia across all time-points evaluated. Results are representative of two independent experiments.