Developmental stage specific metabolic and transcriptional activity of chlamydial elementary bodies and reticulate bodies in an axenic medium

Chlamydia trachomatis is a significant human pathogen yet their obligate intracellular nature severe restrictions upon research. Chlamydiae undergo a complex developmental cycle characterized by an infectious cell type known as the elementary body (EB) and an intracellular active replicative form called the reticulate body (RB). EBs have historically been described as metabolically dormant. A cell-free (axenic) culture system was developed which showed high levels of metabolic and biosynthetic activity from both EBs and RBs. EBs preferentially utilized glucose-6-phosphate as an energy source whereas RBs required ATP. Both developmental forms showed improved activity when incubated under microaerobic conditions. Incorporation of isotopically-labeled amino acids into proteins from both developmental forms indicated unique expression profiles which were confirmed by genome-wide transcriptional analysis. The described axenic culture system will greatly enhance biochemical and physiological analyses of chlamydiae. Chlamydia axenic metabolic activity