Figure 1.

Chlamydia trachomatis infection is delayed in 3D organotypic cultures. (A) Diagram of the 3D cultures set up for the differentiation, stratification, and infection stages. (B) C. trachomatis L2 inclusions (red) in organotypic cultures infected for 1 or 5 days were only present on the top-most layers. An anti-C. trachomatis LPS antibody was used to detect inclusions. White line represents the bottom of the 3D culture. A representative image from four independent experiments is shown. Scale bar = 10 μm. (C) TEM micrographs show C. trachomatis L2 inclusions containing only normal-size RBs independently of the time of infection, 1, 3, or 5 days. Black arrowheads point at cells that were either being shed or undergoing cell death. A representative image from three independent experiments is shown. (D) Quantification of inclusion contents and the area of elementary bodies (EBs), reticulate bodies (RBs) and intermediate bodies (IB) in 3D cultures infected from the top for 1 (green line) or 3 days (blue line). The dotted line indicates the area distribution for chlamydial organisms in productive infections. White scale bar = 2 μm; black scale bar in inset = 500 nm.