Transcriptional expression of C. abortus 16S rRNA (A) and omp1 (B) RNA. Cells were infected with C. abortus (MOI 2). RNA and DNA were harvested between 6 and 72 h p.i. RNA transcript levels were analyzed by reverse transcription quantitative PCR and normalized against numbers of chlamydial genomes (see Materials and Methods). ± SEM of three independent experiments (see Materials and Methods). * p < 0.05 above baseline levels.