![]() The assay was tested using a 649-member panel of specimens from diverse global locales, 13 HIV-1 seroconversion panels, a panel representing seven of the primary HIV-1 subtypes, an HIV-2 panel, an HIV-1/HIV-2 mixed panel, and 100 prospectively tested specimens. In order to maximize HIV-specific antibody capture, multibranched peptides (MBP) for both HIV-1 and HIV-2 ( 22) were evaluated for use in a single assay that could detect and differentiate HIV infections. The purpose of this study was to develop a quantifiable lateral-flow test for the detection and differentiation of antibodies to HIV-1 and HIV-2 using magnetic-bead markers (magnetic immunochromatography test ). Thus, detection of antibodies generated to a variety of HIV subtypes might be improved through the use of a broader antigenic mix (chimeric recombinant proteins or synthetic peptides) and/or a more effective antigenic presentation (multibranched peptides), both of which have proven useful in diagnostic assays for HIV and other infectious agents ( 13, 15, 19, 22). Furthermore, the development of assays for HIV incidence determinations has shown that the immune responses to subtype B antigens are not equivalent across HIV subtypes ( 21) and that multisubtype antigens are more effective at establishing comparable incidence measurements in international cross-sectional surveys. However, how these assays perform during early seroconversion with non-subtype B infections has not been assessed, since panels for other subtypes are unavailable. Current commercial assays have been shown to perform well with specimens from individuals infected with other HIV-1 subtypes, even group O ( 4, 23). Such devices could also be used to develop quantitative lateral-flow tests for a variety of diagnostic applications.įor rapid HIV testing, lateral-flow tests primarily use HIV-1 subtype B antigens from the immunodominant transmembrane region to capture HIV-specific antibodies. Diagnostic-instrument manufacturers have responded by developing lateral-flow strip readers that use reflectance, fluorescence, and magnetic measurements to provide a more precise and objective result ( 7, 14). Investigations to determine the sources of these problems have not identified any particular trait other than the subjective interpretation of the results ( 3). Although they are generally easy to interpret by visual inspection, there are reports of false-reactive devices, particularly in low-prevalence settings ( 6). The tests are rapid, inexpensive, and stable over a broad temperature range and are simple to perform, requiring no additional equipment ( 1). These assays are primarily designed as lateral-flow formats that use colored detection reagents, such as colloidal gold or selenium, conjugated to HIV antigens or to proteins that bind to specific human immunoglobulins, such as protein A or G ( 10). The use of rapid HIV antibody-screening assays has permitted the global expansion of HIV testing into rural, nonlaboratory settings and has significantly increased the number of individuals that have been screened. MICT can provide a rapid, low-cost method of determining HIV antibody status requiring no subjective interpretations. Assay reproducibility (observed MAR) for both intra- and interrun testing was excellent, with coefficients of variation of <12%. Additionally, 13 HIV-1 seroconversion panels (total specimens = 85), a worldwide panel containing seven of the major circulating HIV-1 subtypes ( n = 18), an HIV-2 panel, an HIV-1/HIV-2 mixed panel, and 100 prospective specimens were tested with completely concordant results. The panel was comprised of samples from individuals infected with various HIV-1 subtypes ( n = 234) or HIV-2 ( n = 65) and HIV-seronegative specimens ( n = 350). The results of the optimized MICT assay were compared to standard enzyme immunoassay (EIA) and Western blotting (WB) results using a blinded 649-member panel of specimens from the United States, Cameroon, and West Africa. Magnetic immunochromatography testing (MICT) uses a standard lateral-flow platform that incorporates magnetic-bead conjugates for quantitative measurement of the magnetic field distortion associated with the bound magnetic conjugate (reported as adjusted relative magnetic units ). A simplified lateral-flow assay for the detection of antibodies to HIV using magnetic-bead conjugates and multibranched peptides from both HIV-1 and HIV-2 was developed.
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