Clinical Evaluation of BioPlex 2200 HIV Ag-Ab, an Automated Screening Method Providing Discrete Detection of HIV-1 p24 Antigen, HIV-1 Antibody, and HIV-2 Antibody

Abstract

bEarly and accurate diagnosis is essential for optimal therapeutic outcomes in patients infected with HIV. Currently, none of the commercially available fourth-generation assays differentiate HIV-1 and HIV-2 antibodies (Ab) or the HIV-1 p24 antigen (Ag). The aim of this study was to evaluate the performance of a novel assay, the BioPlex 2200 HIV Ag-Ab. This assay uses a multiplex flow immunoassay design allowing the simultaneous detection and identification of antibodies to HIV-1 (groups M and O), HIV-2, and the HIV-1 p24 antigen, in addition to providing a traditional composite result. A total of 1,505 routine serum samples were prospectively tested. Results were compared with those from the Architect HIV Combo assay. The sensitivity of the BioPlex 2200 was 100%. The specificity assessed on repeated false-positive samples was 99.5%. In addition, 524 frozen specimens from patients known to be infected with HIV-1 or HIV-2 were tested. Of these specimens, 420 were infected with HIV-1, including 156 of known genotypes, 86 were infected with HIV-2, 7 were infected with HIV-1 and HIV-2, and 11 were from patients with acute HIV infection. Sensitivity was 100% for the HIV genotypes tested. The differentiation capabilities of the BioPlex 2200 HIV Ag-Ab assay for HIV-1, HIV-2, dual HIV-1/HIV-2, and early infections were 100%, 90.7%, 100%, and 90.9%, respectively. The BioPlex 2200 is a sensitive and specific assay that offers advantages over conventional HIV combo assays, also referred to as fourth-generation assays, to accurately differentiate and report HIV-1 p24 antigen and HIV-1 and HIV-2 antibodies.

New Automated Chemiluminescence Immunoassay for Simultaneous but Separate Detection of Human Immunodeficiency Virus Antigens and Antibodies

“…In our study, we recorded 6 false-positive results: 3 in samples from subset A (prospective) and 3 in samples from subset C (screen positive only). The specificity of Liaison XL Murex HIV Ab/Ag was 99.2% in the prospective and confirmed positive populations (98.5% when samples from subset C were included), i.e., similar to that reported by Salmona et al (99.5%) (16).…”

“…Salmona et al (16) recently evaluated the BioPlex 220 assay, which also separately detects antibody and antigen. The sensitivity of the BioPlex 2200 was also 100%.…”

“…In the literature, specificity values for fourth-generation assays range between 97.6% and 99.8% (16,17). Several studies have suggested lower specificity of fourth-generation assays because of the combination of 2 different test principles (3,12,18).…”

“…Since the prevalence of HIV type 2 is low in Spain (22), the use of a HIV-1 WB assay as the sole confirmatory test is common. Consequently, HIV-2-infected individuals can be misclassified as HIV-1 positive because of the cross-reactivity between HIV-2 antibody and envelope glycoproteins of HIV-1 (16). In the present study, 1 specimen was considered non-HIV infected by the standard algorithm because the WB was nonreactive; the HIV-2 WB assay was performed based on the patient's epidemiological history.…”

Human Immunodeficiency Virus Diagnostic Testing: 30 Years of Evolution

“…Specimens reactive only for the p24 antigen do not need an antibody confirming procedure, and specimens reactive only for antibody do not require an antigen confirmatory procedure. Salmona et al evaluated the BioPlex fifth-generation assay and found 100% sensitivity and 99.5% specificity in a study of 1,505 patients (16). As of January 2016, the CDC has not published a fifth-generation testing algorithm.…”