Multicenter Evaluation of a New, Automated Enzyme-Linked Immunoassay for Detection of Human Immunodeficiency Virus-Specific Antibodies and Antigen

Abstract

A collaborative multicenter study was conducted to evaluate the sensitivity, specificity, and precision of a three-step, fully automated, qualitative microparticle-based enzyme-linked immunoassay (AxSYM HIV Ag/Ab Combo; Abbott Laboratories), designed to simultaneously detect (i) antibodies against human immunodeficiency virus type 1 (HIV-1) and/or type 2 (HIV-2) and (ii) HIV p24 antigen. A significant reduction in the HIV seroconversion window was achieved by combining detection of HIV antibodies and antigen into a single assay format. For 22 selected, commercial HIV seroconversion panels, the mean time of detection with the combinedformat HIV antigen-antibody assay was reduced by 6.15 days compared to that with a similar third-generation single-format HIV antibody assay. The quantitative sensitivity of the combination assay for the p24 antigen (17.5 pg/ml by use of the p24 quantitative panel VIH SFTS96) was nearly equivalent to that of single-format antigen tests. The combination assay demonstrated sensitive (100%) detection of anti-HIV immunoglobulin in specimens from individuals in CDC stages A, B, and C and from individuals infected with different HIV-1 group M subtypes, group O, or HIV-2. The apparent specificity for hospitalized patients (n ‫؍‬ 1,938) was 99.90%. In a random population of 7,900 volunteer blood donors, the specificity (99.87%) was comparable to that of a third-generation single-format HIV antibody assay (99.92%) on the same donor specimens. In addition, the combination assay was robust to potential interfering specimens. The precision of the combination was high, with intra-and interrun variances of <9.3% for each precision panel specimen or assay control and <5.3% for the negative assay control.

Use of a New Dual-Antigen Enzyme-Linked Immunosorbent Assay To Detect and Characterize the Human Antibody Response to the Human Immunodeficiency Virus Type 2 Envelope gp125 and gp36 Glycoproteins

“…Therefore, 100% clinical specificity was obtained for both polypeptides. The 100% specificity of the ELISA-HIV2 assay compares favorably to the specificity of the two licensed HIV-2 serodiagnosis assays (Ͻ92%) (2, 7) and to the specificity of most mixed HIV-1/HIV-2 assays (mean, 99%; range, 94.6% to 100% for assays based on recombinant proteins; mean, 98%; range 90.4% to 100% for assays based on synthetic peptides) (1,4,5,12,14,22,28,31,38,42,43,45,48).…”

“…The gp36 ectodomain is highly conserved and elicits a type-specific antibody response (13,33). Hence, most licensed diagnostic assays incorporate gp36-derived antigens to detect HIV-2-specific antibodies (1,4,12,28,29,38,42,45,48). The sensitivity of these assays to detect HIV-2 seroconversions has not been formally tested.…”

PHS Guideline for Reducing Human Immunodeficiency Virus, Hepatitis B Virus, and Hepatitis C Virus Transmission through Organ Transplantation

“…36,[154][155][156][158][159][160][161][162] Five studies reported differences in window period time from third-generation Ab and polymerase chain reaction (PCR) assays using seroconversion 292  PHS Guideline Public Health Reports / July-August 2013 / Volume 128 panels. Fourth-generation assays were reactive and ranged from 0 to 6.15 days before thirdgeneration Ab assays.…”

“…Test sensitivity and specificity were calculated in five analytic and three clinical studies, with a sensitivity of 100.0% [154][155][156][157][158][159][160] and a specificity range of 82.5%-100.0%. 36,[154][155][156][158][159][160][161][162] Five studies reported differences in window period time from third-generation Ab and polymerase chain reaction (PCR) assays using seroconversion 292  PHS Guideline Public Health Reports / July-August 2013 / Volume 128 panels.…”

Combination Assay Detecting both Human Immunodeficiency Virus (HIV) p24 Antigen and Anti-HIV Antibodies Opens a Second Diagnostic Window

“…These studies have shown that the diagnostic window period is reduced by several days to as much as 2 weeks depending on the tests used. In one study (7), the AxSYM HIV Ag/Ab Combo assay became reactive a mean of 6.15 days before the AxSYM HIV-1/2 Antibody gO assay.…”