Identification of the epitope recognized by a specific VHH raised against the Th17 antigen (AID45212)

Segmented filamentous bacteria (SFB) are ubiquitous intestinal commensals that promote immune system development and pathogen protection. The unicellular teardrop-shaped SFB, called intracellular offsprings (IOs), attach to ileal epithelial cells via their unique tip structure and outgrow into filaments. To obtain a more detailed view of the SFB surface, particularly at the tip structure, we used a combination of cryo-EM and cryo-ET to characterize the surface structures present in IOs and filaments from mouse- and rat-SFB. HDX-MS was used to identified the epitope recognized by a specific VHH raised against the Th17 antigen (AID45212) located at the SFB surface.