title: Isolation of protective antigen from Bordetella pertussis.
mesh_terms: D000941:Antigens / Q000032:analysis*; D001886:Bordetella pertussis / Q000276:immunology*; D002499:Centrifugation, Density Gradient; D004586:Electrophoresis; D008854:Microscopy, Electron
chemical_list: D000941:Antigens