The T3SS structural and effector genes of Chlamydia trachomatis are expressed in distinct phenotypic cell forms

<i>Chlamydia trachomatis</i>, a sexually transmitted bacterial infection, poses a significant global health threat, causing over 100 million infections annually and leading to complications like ectopic pregnancy and infertility. This study investigates the gene expression patterns of <i>C. trachomatis</i> during its unique life cycle within human cells. As an obligate intracellular parasite, <i>C. trachomatis</i> transitions through distinct developmental stages-one for infection and dissemination, another for replication, and a third for transitioning back to the infectious form. By analyzing gene expression profiles at each stage, we identified key genes involved in these processes. Interestingly, our research also reveals the presence of two separate type III secretion system (T3SS) translocons expressed in distinct stages, suggesting their crucial roles in specific functions during the infection cycle.