Evaluation of a new third-generation ARCHITECT rHTLV-I/II assay for blood screening and diagnosis.

In comparison to current on-market assays, the ARCHITECT rHTLV-I/II assay is the first fully automated assay that simultaneously detects human T-cell lymphotropic virus type I (HTLV-I) and type II (HTLV-II) in human serum and plasma. Specificity was assessed on 5646 blood donors and 692 clinical specimens. For sensitivity determination, 301 HTLV-I-positive and 105 HTLV-II-positive specimens were tested. Precision was between 3.98% and 4.31% coefficient of variation (CV) for specimens with 1 to 6 sample to cutoff. Specificity was 99.95% and 99.86% on specimens from blood donors and hospitalized patients, respectively. Sensitivity evaluation showed 100% detection on 301 HTLV-I and 105 HTLV-II specimens. HTLV-I and HTLV-II viruses are still circulating among general populations even in the low prevalence areas. To control the further spread of these retroviruses, we need to know that it is important to continue screening of blood. The performance evaluation data from this study demonstrate that the high throughput and fully automated ARCHITECT rHTLV-I/II chemiluminescence immunoassay effectively serves this purpose.

Evaluation of the Abbott ARCHITECT Toxo IgM assay.

Development of the ARCHITECT Toxo IgM assay has been done to assist the clinician in acute Toxoplasma gondii infection detection, especially in pregnant women. Its use, in conjunction with ARCHITECT Toxo IgG and Toxo Avidity assays, will provide an array of assays particularly useful in the monitoring of pregnant females to determine the risk of maternal transmission of the parasite. Specificity results from 2 testing sites, using populations of pregnant females, hospital patients, and blood donors, demonstrated that the assay has an overall resolved relative specificity of 99.89% (confidence interval, 99.68-99.98%). Relative specificity for pregnant female specimens was 99.95% (n = 2031). Excellent seroconversion sensitivity was observed for the ARCHITECT Toxo IgM assay, which was similar to the Abbott AxSYM Toxo IgM assay (Abbott Laboratories, Abbott Park, IL). In more than 90% of the panels tested, the 1st bleed detected in the serial bleeds was the same for both assays.

Performance characteristics of the new ARCHITECT Toxo IgG and Toxo IgG Avidity assays.

The ARCHITECT Toxo IgG and IgG Avidity assays have been developed as a fully automated panel for immune status determination and acute infection exclusion. Resolved relative specificity and sensitivity of the ARCHITECT Toxo IgG assay were 99.6% (1359/1365) and 99.7% (1096/1099) as determined on pregnant females, blood donor, and diagnostic specimens. Seroconversion sensitivity of the ARCHITECT assay was comparable with the AxSYM Toxo IgG assay. The ARCHITECT Toxo IgG Avidity assay detected 100.0% (124/124) of acute phase specimens (<4 months after infection) as low avidity, whereas the Vidas Toxo IgG Avidity assay detected 98.9% (89/90) as low avidity. In summary, the ARCHITECT Toxo IgG assay, using recombinant antigens, showed excellent specificity and sensitivity for acute phase as well as past infection specimens. The ARCHITECT Toxoplasmosis panel can be reliably used to rule out acute Toxoplasma gondii infection in pregnant women.

Performance evaluation of the new fully automated human immunodeficiency virus antigen-antibody combination assay designed for blood screening.

BACKGROUND: Before the introduction of human immunodeficiency virus (HIV) combination assays, serologic diagnosis of HIV infection was performed with assays that detected either antibodies or p24 antigen. Owing to the capability to detect the early appearance of p24 antigen, combination assays that are designed for simultaneous detection of antibodies and antigen can significantly reduce the diagnostic window. STUDY DESIGN AND METHODS: Specificity and sensitivity of a commercially available HIV antigen-antibody combination assay (Abbott PRISM; assay is not licensed by the FDA for use in the United States) were evaluated in a multicenter study by testing volunteer blood donors, hospitalized patients, seroconversion panels, and p24 antigen and HIV antibody subtype panels. Performance data were compared to a commercially available HIV combination assay and the PRISM HIV O Plus assay. RESULTS: Apparent specificity of 99.95 percent was observed in the donor population for the PRISM HIV antigen-antibody combination assay, and better seroconversion sensitivity was demonstrated compared with another combination assay and the PRISM HIV O Plus assay. Analytical HIV antigen detection sensitivity averaged 33 pg per mL on the Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSAPS) panel. Furthermore, comparable antigen sensitivity was demonstrated for 32 HIV-1 group M subtype and group O panels. The PRISM HIV combination assay detected all HIV-1 group M and O and HIV-2 antibody-positive specimens evaluated. CONCLUSIONS: The PRISM HIV antigen-antibody combination assay demonstrated a significant reduction of the window period for diagnosis of HIV infection. The assay demonstrated enhanced specificity and sensitivity along with broad subtype detection. The assay performance represents the "state-of-the art" technology for serologic blood screening of HIV infection.

Multicenter evaluation of a new, automated enzyme-linked immunoassay for detection of human immunodeficiency virus-specific antibodies and antigen.

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 combined-format 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 = 1938) was 99.90%. In a random population of 7900 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