File:Selective-Infection-of-Antigen-Specific-B-Lymphocytes-by-Salmonella-Mediates-Bacterial-Survival-and-pone.0050667.s007.ogv

English: GFP-Salmonellae excreted from human primary B cells are capable of infecting 3T3-CD40L fibroblasts. Living primary human B cells infected with GFP-expressing Salmonella were co-cultured with CD40L-expressing 3T3 cells, and imaged by widefield fluorescence microscopy at 37°C. Depicted are GFP and Texas-Red signals projected on the transmission image. Images are collected every 30 min. 5 hours after the onset of the experiment a single human primary B cell infected with a GFP-expressing Salmonella moves from a distant location into the viewing plane from the upper right corner. The bacterium is excreted from the B cell and subsequently infects the 3T3-CD40L monolayer followed by rapid growth of Salmonella in the 3T3-CD40L cells. This further demonstrates that growth of the bacterium is actively suppressed inside the human primary B cell, while its viability is maintained. Primary B cells thus form a survival niche for Salmonella. Total duration: 15 hours.