In Murex ELISA, the HIV antigens comprise the highly purified immunodominant antigens of the core and envelope proteins of HIV-1 and an immunodominant peptide of the HIV-2 envelope. In Vironostika ELISA, the HIV antigens are a mixture of HIV-1 p24, HIV-1 gp160, HIV-1 ANT70 peptide, and HIV-2 env peptide (amino acids 592 to 603). In HIVSPOT, the capture HIV proteins are the recombinant protein of HIV-1, corresponding to a region overlapping the junction between the gp120 and gp41 fragment of the env protein, plus a highly purified peptide which corresponds to a region of the envelope transmembrane protein of HIV-1. Only discrepant results were then evaluated by WB (HIV Blot 2.2 Genelabs Diagnostics). Specimens testing reactive were then confirmed by another methodologically different ELISA (HIV 1+2 Murex Biotech Ltd., Dartford, United Kingdom). HIV screening for samples from other studies was initially performed with an ELISA (Vironostika-HIV Uni-Form II plus O). The algorithm for HIV testing is shown in Fig. Specimens giving discordant results or those testing reactive by both rapid test and ELISA were then confirmed by WB (HIV Blot 2.2 Genelabs Diagnostics). HIV screening for samples from ENARP cohorts was performed by a rapid test (HIVSPOT Genelabs Diagnostics, Singapore) and ELISA (Vironostika-HIV Uni-Form II plus O Organon Teknika, Boxtel, The Netherlands). The ARC criteria best met the specified objectives for diagnosis in our setting. In general, there was 97.8% concordance between the ARC and WHO criteria and 85.7% concordance between the ARC and CDC criteria for an indeterminate WB result. In addition, 17 indeterminate samples were negative when assessed by a nucleic acid-based amplification assay for HIV-1 viremia. Using CDC and WHO criteria, 6 (19.4%) and 2 (6.5%), respectively, of these WB assays would have been considered falsely positive. Of 31 WB assays initially indeterminate by the ARC criteria and with follow-up samples, 29 (93.5%) became negative when retested subsequently while 2 (6.5%) remained indeterminate for more than a year and were thus considered negative. Only two samples (2.2%) were reactive to both env glycoproteins gp41 and gp120/160 (positive by the World Health Organization criteria). However, 12 samples (13.2%) displayed reactivity to p24 and gp41 or to p24 and gp120/160 proteins (positive by Centers for Disease Control and Prevention criteria). Most (30.4%) of these indeterminate WB results were due to p24 reactivity. Ninety-one (≈0.8%) gave equivocal results because of discordant results among the various screening assays and indeterminate WB profiles by the American Red Cross (ARC) criteria. Overall, 1,437 (11.9%) were positive for HIV-1 antibody. Between 19, a total of 12,124 specimens were tested for HIV-1 antibodies. Here, we describe the profiles of indeterminate WB reactivity in Ethiopians with discordant screening assays. The profiles of WB reactivity among Ethiopians are hardly known. However, indeterminate WB reactivity to HIV-1 proteins may occur in individuals who do not appear to be infected with HIV. Probability of a false-negative HIV antibody test result during the window period: A tool for pre- and post-test counselling.The Western blot (WB) assay is the most widely accepted confirmatory assay for the detection of antibodies to human immunodeficiency virus type 1 (HIV-1). Taylor, D., Durigon, M., Davis, H., Archibald, C., Konrad, B., Coombs, D., … Ogilvie, G.HIV in the United States and Dependent Areas (2019, January).How do HIV tests work and what's involved? (2018, January 24).Detection of HIV-1 p24 antigen in patients with varying degrees of viremia using an ELISA with a photochemical signal amplification system. You can learn more about how we ensure our content is accurate and current by reading our editorial policy. We link primary sources - including studies, scientific references, and statistics - within each article and also list them in the resources section at the bottom of our articles. Medical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations.
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