In the usual sequential addition enzyme immunoassays for drugs, the activity of the drug-labeled enzyme decreases continuously with time as more of it is bound to antibody. Sensitivity also decreases; the activity immediately after mixing is the most sensitive indicator of drug concentration. The reaction of enzyme-drug with antibody can be stopped by saturating the antibody with a larger quant...

Several kinds of laboratory techniques are available to detect Clostridium difficile toxin in fecal samples. Because questions have been raised about the reliability of immunoassays compared to the accepted standard, cytotoxicity assay, we studied three enzyme immunoassays (EIAs) and one rapid EIA, which demonstrated relatively good sensitivities and specificities compared to cytotoxicity assay.

Commercially available immunoassays for assessment of anti-streptolysin-O antibodies use native streptolysin-O obtained by a complex process. We prepared a biologically active recombinant streptolysin-O with higher yield and a simpler purification process. An enzyme-linked immunosorbent assay developed with this recombinant showed good correlation with a commercial test, suggesting that it coul...

background and aims: some nanoparticles can be used in immunoassays to increase sensitivity. this study aimed to evaluate a novel nano-immunoassay based on bovine serum albumin nanoparticles (bsa nps). materials and methods: at first, the nanostructure was synthesized, and then applied as a tag in the nano-immunoassay. then the concentration of β-subunit of human chorionic gonadotropin (βhcg) i...

Enzyme-linked immunoassays based on an antibody-antigen interaction are widely used in biological and medical sciences. However, the conjugation of an enzyme to antibodies needs an additional chemical process, usually resulting in randomly cross-linked molecules and a loss of the binding affinity and enzyme activity. Herein, we present the development of an alkaline phosphatase-fused repebody a...

E70 CMAJ, January 10, 2012, 184(1) © 2012 Canadian Medical Association or its licensors Serological surveillance (serosurveillance) provides estimates of population-level immunity against vaccine-preventable diseases using cross-sectional studies of antibody prevalence. Seroepidemiology is important for evaluating the impact of vaccination programs, as these programs change the immunity of popu...

We investigated the effect of multiple freeze-thaw cycles on mumps, measles, and rubella virus serum antibody levels with whole-virus immunoglobulin G enzyme-linked immunoassays. Fresh serum samples from nine healthy adult volunteers were divided into six sets of five aliquots each. Samples were taken through a total of 10 freeze-thaw cycles and stored at 4 degrees C until assayed. Each assay m...

Third-generation enzyme immunoassays start to de tect anti-HIV antibodies within 20–22 days after exposure; fourthgeneration enzyme immunoassays, which test for p24 antigen and anti-HIV antibodies, can yield positive re sults within 16–18 days. RNA nucleic acid amplification testing starts to de tect HIV infection within 7–14 days. At $75 per test, these RNA tests are too costly for routine use...