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Transmission electron micrograph of S. flexneri 2a vaccine strain CVD 1208S expressing CFA/I fimbriae. CVD 1208S-CFA/I was suspended on a 300 mesh Formvar coated grid and stained with 2% ammonium molybdate. The image was examined using a JEOL electron microscope JEM-1200EX and is shown at 1500X; the scale bar represents 100 nm.
