Study on the use of an enzyme-linked immunosorbent assay in determining human antibodies to diphtheria toxin as compared with a reference toxin neutralization assay.
Serum samples from 156 Greek persons were assessed by an IgG-specific enzyme-linked immunosorbent assay (ELISA) and a reference tissue culture toxin-neutralization (TN) assay for the quantitation of diphtheria toxin antibodies. By the reference method, 7.7% of the persons were susceptible to diphtheria (antitoxin < 0.01 IU/ml), 28.8% had basic protection (antitoxin 0.01-0.09 IU/ml) and 63.5% were fully protective (antitoxin > or = 0.1 IU/ ml), while the corresponding figures were 17.9, 36.5 and 45.5% when they were tested by the immunoassay. None of the samples been susceptible by the TN assay were found to have some protection when tested by ELISA. However, three (6.7%) of the 45 samples showing a basic protection with TN, were fully protective when titrated by the immunoassay. In addition, 31 (31.3%) of the 99 samples been fully protective by the bioassay, were found to be either basically protective or susceptible by means of the ELISA. Overall, validity features of the immunoassay were: sensitivity 68.7%, specificity 94.7%, positive predictive value 95.8% and negative predictive value 63.5%. The ELISA tested in our study could be used to determine diphtheria antitoxin in individuals needed a booster immunization (susceptible or basic protective samples), although it might falsely include in the above categories samples that are within the fully protective levels of antibodies.
Skoura
L
L
Department of Microbiology, AHEPA University Hospital, Thessaloniki, Greece.
Efstratiou
A
A
Tsakris
A
A
Pournaras
S
S
George
R C
RC
Douboyas
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000032:analysis* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004165:Diphtheria / Q000276:immunology*; D004167:Diphtheria Toxin / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis / Q000378:metabolism; D007223:Infant; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests / Q000379:methods*; D012016:Reference Values
D000907:Antibodies, Bacterial; D004167:Diphtheria Toxin; D007074:Immunoglobulin G