These data indicate that the automated, microparticle-based chemiluminescent HCV core antigen assay can reduce the window period for detection of potentially infected blood donors by 32.7 days, and it represents a viable alternative to HCV RNA testing.

The distribution of immune complexes has been studied in mouse spleen stimulated to contain many germinal centers (GC's). Horseradish peroxidase (HRP)-anti-HRP complexes were used as an appropriately precise and sensitive model. We were primarily interested in the relative abilities of three cell types to interact with complexes: lymphocytes, macrophages, and follicular dendritic cells (FDC's). The latter are distinctive, nonendocytic, stellate cells located primarily at the transition of mantle and GC zones of 2 ~ lymphoid follicles (Chen, L. L., J. C. Adams, and R. M. Steinman, 1978, J. Cell Biol. 77"148).Binding of immune complexes to lymphocytes could not be visualized in situ. Macrophages avidly interiorized complexes into lysosomes, but did not retain them extracellularly. In contrast, FDC's could retain HRP-anti-HRP extracellulady under appropriate conditions, but did not endocytose them. Cytochemical reactivity accumulated progressively on FDC's 1-6 h after administration of complexes i.v., remained stable in amount and location for 1 day, and then was progressively lost over a 1-to 5-day period.Several variables in the association of complexes with macrophages and FDC's were pursued. Only 1 /~g of complexed HRP had to be administered to visualize binding to both cell types. Macrophages interiorized complexes formed in a wide range of HRP/anti-HRP ratios, while FDC's associated with complexes formed in HRP excess only. Quantitative studies with [12SI]HRP-anti-HRP demonstrated that 20% of the splenic load of HRP associated with FDC's. Complexes formed with an F(ab')~ anti-HRP were distributed primarily in macrophages. When the levels of the third component of serum complement were depleted by prior treatment with cobra venom factor, uptake of complexes by macrophages was reduced some 50% whereas association with FDC's was abolished.The fact that antigen excess complexes are retained extracellularly strengthens the idea that they are immunogenic. Finally, the association of complexes with FDC's seems to retard the entry of antigen into the GC proper.J. CELL BIOLOGY 9 The Rockefeller University Press 9 0021-9525/78

The results demonstrated that the Abbott RealTime HIV-1 assay with DBS sample protocol is highly sensitive, specific and precise across a wide dynamic range and correlates well with plasma values. The Abbott RealTime HIV-1 assay with DBS sample protocol provides an alternative sample collection and transfer option in resource-limited settings and expands the utility of a viral load test to monitor HIV-1 ART treatment for infected patients.

Nucleic acid amplification test (NAAT)-based assays provide fast and sensitive results compared to conventional TB tests. The performance of the new Abbott Molecular MTB assay for the qualitative detection of MTB complex using the automated m2000™ system or manual sample preparation is summarized in this paper. The assay detects eight MTB complex subspecies. The observed limit of detection (LOD) when used to test an MTB H37Rv panel was 2.45 colony forming units (cfu)/mL, while the claimed assay LOD with this MTB strain is 17 cfu/mL. No cross reactivity, or carryover were observed in the study. The clinical sensitivity of the assay was 93% overall; 99% in smear positive, culture positive specimens, and 81% in smear negative, culture positive samples. The clinical specificity was 97%. The inhibition rate in the study was 0.34%. The data suggest that Abbott RealTime MTB is a reliable, robust and sensitive assay for the molecular detection of MTB.