title: Quantitative detection of type A staphylococcal enterotoxin by Laurell electroimmunodiffusion.
abstract: The detection of staphylococcal enterotoxin A by the quantitative technique of electroimmunodiffusion is described. High dilutions of type-specific rabbit antiserum were used in 1% agarose gels, 1 mm thick, and prepared in 0.05-mug barbital buffer, pH 8.6. Volumes of 10 muliters containing 1.5 to 10 ng of toxin were electrophoresed out of 4-mm diameter wells at 5 mA/cm width of gel. The precipitin cones formed were made visible by first immersing the agarose gels in 0.2 M NaCl and then overlaying the surface with the purified globulin fraction of sheep serum against rabbit globulin, followed by soaking of the gels in 1% aqueous cadmium acetate and staining with 0.1% thiazine red in 1% glacial acetic acid. Fully extended cones, 4 to 23 mm in length depending on toxin concentration and antiserum dilution, were developed in 2 to 5 h of electrophoresis, and visualization was achieved within 2 to 3 h. Because the method is qualitative, quantitative, simple, rapid, and sensitive, it offers a practical tool for the detection of small amounts of bacterial toxins in contaminated foods. The method should also qualify as a sensitive detection device in biochemical procedures which attempt to trace, detect, and identify biological substances in nanogram quantities, provided these substances are antigenic and capable of forming a precipitate with their specific antibodies.
mesh_terms: D000818:Animals; D004586:Electrophoresis; D004768:Enterotoxins / Q000032:analysis*; D005069:Evaluation Studies as Topic; D005506:Food Contamination; D005516:Food Microbiology; D007106:Immune Sera; D005779:Immunodiffusion; D008722:Methods; D011817:Rabbits / Q000276:immunology; D012703:Serotyping; D013210:Staphylococcus / Q000032:analysis*
chemical_list: D004768:Enterotoxins; D007106:Immune Sera