Improved Specificity of a Multiplex Immunoassay for Quantitation of Anti-Diphtheria Toxin Antibodies with the Use of Diphtheria Toxoid

ABSTRACTA nonspecific binding of antibodies to diphtheria toxin, especially in adult serum samples, was observed in our diphtheria-tetanus-pertussis multiplex immunoassay (DTaP4 MIA). This can be significantly reduced by the use of diphtheria toxoid, achieving a good correlation with the Vero cell neutralization test and the toxin binding inhibition assay.

Binding Inhibition Assay Using Fiber-Optic Based Biosensor for the Detection of Foodborne Pathogens

Frequent outbreaks of foodborne illness have been increasing the need for simple, rapid and sensitive methods to detect foodborne pathogens. Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Among the biosensors, fiber-optic methods have much potential because they can be very sensitive and simple to operate. Fiber-optic biosensors typically use a light transmittable, tapered fiber to send excitation laser light to the detection surface and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to fluorophor-labeled biomolecules immobilized on the fiber surface. A portable and automated fiber-optic biosensor, RAPTOR (Research International, Monroe, WA), was used to detect Salmonella enteritidis in food samples. A binding inhibition assay based on the biosensor was developed to detect the bacteria in hot dog samples. The biosensor and the binding inhibition assay could detect 104 cfu/ml of bacteria in less than 10 min of assay time.