Determination of diphtheria toxin neutralizing antibody titers with a cell protein synthesis inhibition assay.
A method which allows an accurate determination of very low titers of antibodies able to neutralize diphtheria toxin has been developed. The assay is based on the incubation of a reference amount of diphtheria toxin with different dilution of the serum and the evaluation of the residual toxicity of diphtheria toxin on Vero cells. The cells are seeded in 96-well plastic plates with the toxin-serum mixtures and the residual toxin activity is measured as the block of cell protein synthesis after incubation with [14C]leucine. Antitoxin titers as low as 0.002 IU can be reproducibly and accurately measured and the method gives a linear response in the range 0.002 to 8.0 IU/ml.
Padovan
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Centro C.N.R. Biomembrane e Istituto di Patologia Generale, Università di Padova, Italy.
Papini
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Rappuoli
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R
Montecucco
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C
D000818:Animals; D001681:Biological Assay / Q000379:methods*; D004166:Diphtheria Antitoxin / Q000032:analysis*; D004167:Diphtheria Toxin / Q000633:toxicity; D006801:Humans; D009500:Neutralization Tests; D014176:Protein Biosynthesis; D014709:Vero Cells
D004166:Diphtheria Antitoxin; D004167:Diphtheria Toxin