Figure 1. Immunization of C3H/HeJ mice with C. trachomatis L2R.

A) A group of 72 progesterone treated female C3H/HeJ mice were infected intravaginally (1° immunization) with 4×10⁷ IFU/mouse (10 ID₅₀). Control mice were sham infected with SPG only. Chlamydial cervico-vaginal shedding was monitored by swabbing the vaginal vault and performing cultures on monolayers of HeLa 299 cells at 3, 7, 14, 21 and 28 days post infection (dpi). Infectious loads in cervico-vaginal swabs were determined following immunostaining of methanol fixed cells and calculating inclusion forming units (IFU). Fifty mice received a second infection (2° immunization) at 35 dpi, 7 days after clearance of the 1⁰ infection. The filled circles and squares represent the mean number of recoverable IFUs ± SEM in 1⁰ and 2⁰ infected mice, respectively. The number of culture-positive mice per total mice at each culture time point during 1° L2R infection (B), or 2° (C). The numbers in parenthesis represent the percent of infectivity.