High-Resolution Detection of Sphingolipids During Chlamydia trachomatis Infection via Expansion Microscopy.

The obligate intracellular bacterial pathogen Chlamydia trachomatis establishes a membrane-bound compartment called the inclusion, which serves as a replicative niche, within host cells. Sphingolipids, a major class of eukaryotic membrane lipids, are acquired from the host and incorporated into chlamydial membranes. Visualization of individual bacteria within inclusions or sub-bacterial structures by fluorescence microscopy remains challenging due to the limited resolution of conventional light microscopy. Expansion microscopy (ExM), a super-resolution imaging technique, enables nanoscale resolution on standard confocal microscopes and is an ideal tool to study Chlamydia infections. However, current ExM protocols are not compatible with sphingolipid visualization. Here, we present a strategy that enables ExM-based imaging of sphingolipids during C. trachomatis infection.