RESUMEN
Most commercially available enzyme immunoassay-based methods have limited sensitivity to detect antibody responses to varicella-zoster virus (VZV) in vaccinated individuals, who produce lower antibody levels than those with natural infection. However, more sensitive methods are either not commercially available or less amenable to high-throughput testing. The BioPlex 2200 measles, mumps, rubella, and varicella (MMRV) IgG assay (Bio-Rad Laboratories, Hercules, CA) is an automated high-throughput platform based on the microsphere Luminex technology that measures antibodies against measles, mumps, rubella, and varicella viruses simultaneously. Although it has U.S. Food and Drug Administration approval as a qualitative diagnostic test for measles, mumps, rubella, and varicella virus immunity, in this study, we have validated the assay to produce quantitative titers (off label) against the VaccZyme VZV glycoprotein (VZVgp) low-level IgG kit (The Binding Site Ltd., Birmingham, UK) using the World Health Organization international standard. Here, we show that the BioPlex 2200 MMRV IgG assay has sensitivity superior to that of the Zeus enzyme-linked immunosorbent assay (ELISA) VZV IgG assay (Zeus Diagnostics, Branchburg, NJ). Using receiver operating characteristic (ROC) analysis and adjusting the cutoff levels, we improved the sensitivity of the quantitative BioPlex 2200 MMRV IgG assay to 97.4%, while maintaining 100% specificity.
Asunto(s)
Anticuerpos Antivirales/sangre , Inmunoensayo/normas , Inmunoglobulina G/sangre , Infección por el Virus de la Varicela-Zóster/diagnóstico , Calibración , Fluorescencia , Herpesvirus Humano 3 , Ensayos Analíticos de Alto Rendimiento/métodos , Ensayos Analíticos de Alto Rendimiento/normas , Humanos , Inmunoensayo/métodos , Técnicas para Inmunoenzimas/métodos , Técnicas para Inmunoenzimas/normas , Microesferas , Juego de Reactivos para Diagnóstico/normas , Sensibilidad y Especificidad , Infección por el Virus de la Varicela-Zóster/sangre , Infección por el Virus de la Varicela-Zóster/inmunologíaRESUMEN
The BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA) is a rapid, automated platform, which can screen large numbers of specimens for antibodies to measles, mumps, rubella, and varicella. Although approved for producing qualitative results, in this study we validated the test (off-label) to allow reporting of quantitative results. To do this, we used the third anti-measles World Health Organization standard to generate a calibration curve that allowed relative fluorescence intensity to be translated into quantitative antibody titer (antibody units [AU]/ml). The results from the BioPlex 2200 and the reference plaque reduction neutralization test (PRNT) exhibited a reasonable correlation following an exponential function, but correlation was poor in low-titer samples. Using a receiver operating characteristics analysis, an equivocal zone for the BioPlex 2200 was established between ≥0.13 and <1.10 AU/ml to achieve 100% specificity (95% confidence interval [CI] = 83.2 to 100%) and 100% sensitivity (95% CI = 93.5 to 100%) versus PRNT. By determining an equivocal range requiring confirmation by PRNT, we can avoid underestimating the levels of immunity through false-negative results and optimize methods for seroepidemiological studies.
Asunto(s)
Anticuerpos Antivirales/sangre , Inmunoensayo/métodos , Inmunoensayo/normas , Virus del Sarampión/inmunología , Automatización de Laboratorios , Calibración , Humanos , Sensibilidad y EspecificidadRESUMEN
The BioRad BioPlex 2200 Vasculitis kit demonstrates excellent relative sensitivity and relative specificity for the semi-quantitative detection of IgG autoantibodies to MPO, PR3 and GBM. The fully-automated platform simultaneously measures three analytes in a single tube, offering superior advantage in speed and ease of use over current assays. The availability of a fully-automated platform with 24-hour availability for these three antibodies may be of considerable value in the differential diagnosis of patients with rapidly progressive glomerulonephritis.