Journal of Clinical Virology 30S1 (2004) S19–S22

The ADVIA Centaur® imunoassay system—designedfor infectious disease testing

David Okrongly∗

Bayer HealthCare LLC, Diagnostics Division, 511 Benedict Avenue, Tarrytown, NY 10591-5097, USA

Abstract

The ability to automate immunodiagnostics testing is critical for the efficiency of clinical laboratories. For automation of Infectious Diseasetesting, special design considerations must be made to ensure the integrity of the testing result while at the same time delivering productivity.The ADVIA Centaur® was designed with the intent of performing a complete Infectious Disease panel including HBV, HCV, and HIV markers.Features such as disposable sample tips, sample and reagent delivery verification, and clog and clog detection have been incorporated in thedesign for assay robustness. Productivity features deliver best in class throughput performance for the Infectious Disease assays. Moreover, theunderlying technology incorporating flexible assay protocols, universal solid phases and proprietary acridinium ester technology contributeto the assay design flexibility and analytical performance of the ADVIA Centaur® immunoassay system.© 2004 Published by Elsevier B.V.

Keywords:ADVIA Centaur® imunoassay system; Infectious disease testing; HIV; HBV; HCV

1. Introduction

Automation in infectious disease serology is rapidly ad-vancing as new technical developments are being made inmethodologies, robotics, and computerization and as a resultof the increasing demand by laboratory managers to improveefficiency, reliability, and quality of testing. In fact, automa-tion is vital for diagnostic laboratories to achieve higher pro-ductivity and better cost efficiencies. Automation can helpto control and guide the workflow and results in a more re-producible process with less direct interaction, which cansignificantly contribute to cost reductions in the laboratory.

Significant advances in automated methods have been ob-tained specifically through the development of modern com-puter systems and engineering techniques. Substantial im-provements have occurred in the solid phase matrix with theuse of microparticles which provide a larger binding sur-face and allow for more uniform and rapid reaction kinetics(Gorman et al., 1997; Wheeler, 2001). Finally, the synthesisof special chemiluminescent compounds has made possiblemultiple measurements in extremely short periods of time(Law et al., 1989; Weeks, 1997).

Abbreviations:IVD, in vitro diagnostics; STAT, statim= immedi-ately; NAD, nucleic acid diagnostics; RLU, relative light units

∗ Tel.: +1-914-524-2090; fax:+1-914-524-2183.E-mail address:david.okrongly.b@bayer.com (D. Okrongly).

Bayer HealthCare, Diagnostics Division continues tomake significant contributions to the progress in laboratoryautomation through the research and development, produc-tion and marketing of clinical diagnostics systems for themajor industry markets of self-testing, near patient testing,laboratory testing, and nucleic acid diagnostics. Bayer isone of the largest and fastest growing medical diagnosticsbusinesses in the world, currently ranking fourth in theworld, with 8000 employees and sales in more than 100countries worldwide. The automated analyzers developedby Bayer are all high throughput systems that process invitro diagnostics (IVDs) and integrate clinical chemistry,immunochemistry, infectious serology, hematology, urinal-ysis, and other hospital and laboratory areas.

2. ADVIA Centaur® immunoassay system

The ADVIA® of Bayer HealthCare represents a familyof products and services designed to improve the long-termvalue of the laboratory within the health care system. Theyhave been designed to offer customized solutions for eachlaboratory applying technology to meet current and futureneeds. Ultimately, the ADVIA portfolio helps the clinicallaboratory to maximize resources and to develop automationand integration approaches.

1386-6532/$ – see front matter © 2004 Published by Elsevier B.V.doi:10.1016/j.jcv.2004.02.006

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Fig. 1. ADVIA Centaur® immunoassay system.

The fully automated, random access ADVIA Centaur im-munoassay system (Fig. 1) has been designed specificallyfor use in large-volume laboratories (Hendriks et al., 2000).New immunoassays for infectious serology of hepatitis Bvirus, hepatitis C virus, and human immunodeficiency virus(HIV) have been developed for the ADVIA Centaur sys-tem. The hepatitis assay panel is composed of assays forHBsAg and HBsAg confirmatory, anti-HBc total, anti-HBcIgM, anti-HBs, and anti-HCV. The infectious disease panelis complemented by an assay for the concomitant detec-tion of anti-HIV-1 (including subtype O) and anti-HIV-2.Other assays currently in development include anti-HAVIgM, anti-HAV total, HBeAg, and anti-HBe.

2.1. Characteristics of ADVIA Centaur assays for HBV,HCV1 and HIV1 markers

The ADVIA Centaur system provides for format flexi-bility, which, in turn allows for many types of particles,coupling chemistries and multiple solid phases in one as-

Table 1ADVIA Centaur immunoassay system—types of infectious disease assays

Name 1-Pass assay 1-Pass extended assay 2-Pass extended assay

Protocol (min) 7.5 20 20:20Time to first reportable result (min) 18 29 58Assays Anti-HBs Rubella G, HBsAg Toxoplasma G, Toxoplasma M, Rubella M, Anti-HBc

total, Anti-HBc IgM, HCV, HIV 1/O/2, Anti-HAVIgM, Anti-HAV total

say (Hendriks et al., 2000; Wheeler, 2001). This flexibilitymakes possible alternative assay architectures with antibodycapture assays (e.g., anti-HBc IgM) and antigen and anti-bodies sandwich assays (e.g., anti-HBs, HBsAg) (Table 1).Such flexibility is supported by the use of small volumeswith onboard pre-treatment steps and dilutions in combina-tion with multiple reagent additions and multiple incubationand wash steps. A very low background signal provides forhigh levels of sensitivity and specificity. For example, theassay for HBsAg, which is a 29 min sandwich assay with apre-incubation of sample and antibodies prior to addition ofsolid phase, offers an analytical sensitivity of 0.066 IU/mlusing the WHO international standard, and 0.1–0.15 ng/mlusing highly purified human-derived HBsAg ad and ay. TheADVIA Centaur can also be set-up for an automated an HB-sAg confirmatory assay or to reflex to other HBV assays.

The anti-HBs assay, which is an 18 min antigen-bridgingassay with a single incubation and wash step, offers alinear measurement between 1 and 1000 mIU/ml. Theassay for anti-HB core total, an antigen-bridging assay

D. Okrongly / Journal of Clinical Virology 30S1 (2004) S19–S22 S21

with two incubations and wash steps, has a throughput of120 tests/h.

The assay for anti-HB Core IgM, a� antibody captureassay with two wash steps and an indirect label, also hasa throughput of 120 tests/h. The assay for anti-HCV onlyrequires 10�l of serum or plasma and has a throughputof 120 tests/h. Finally, the assay for anti-HIV 1/O/2 is amulti-epitope assay with excellent specificity and sensitivity.This assay offers the ability to detect low affinity antibodiesand seroconverters, in great part due to the architecturalflexibility of the ADVIA Centaur that permits incorporatingfour different solid phases bearing different epitopes into theassay.

2.2. Features of the ADVIA Centaur immunoassay system

2.2.1. The system is always ready to startContinuous operation is possible even during the loading

of all reagents, samples and supplies. There are no dailystartup tasks. The samples, which are accommodated intouniversal racks, are loaded and the system runs without anyadditional set-up. The samples can be loaded continuouslyupon receipt, guaranteeing a fast turn-around time (TAT).The system has a true STAT capability. In fact, a dedicatedSTAT port prioritizes STAT samples automatically, withoutfurther operator intervention or disrupting work in progress.The STAT results are available within 18 min, also promptlyproducing initial results much faster than other systems.

2.2.2. The system offers optimal productivityThe ADVIA Centaur system, with its high-throughput

process efficiency of 240 tests/h and a total walk-away timeof 840 tests, is the fastest immunoassay system available to-day. The effective throughput varies with the mix of assaytypes and the number of tests per run (Table 2).

The operator intervention and interaction is significantlyreduced (with up to 3.5 h of unattended operation) due to thehigh sample capacity combined with advanced automationfeatures—including automatic repeat, dilution, and reflextesting.

Minimal hands-on time is required as a result of the largeon-board capacity for reagents and supplies combined withautomated maintenance and monitoring features to stream-line operations.

Table 2Comparison of infectious disease testing across different commerciallyavailable platforms

Instrument Totalprocessingtime (min)

Throughput(tests/h)

ADVIA Centaur 163.0 147Immulite 2000 314.5 76ElecSys 2010 341.7 70AxSYM 398.5 60Vitros Eci 427.4 56

Worklist 400: 200 HBsAg tests; 100 anti-HBs tests; 100 anti-HBc tests.

The system has a large, onboard reagent capacity with re-frigeration for up to 30 different reagent packs and 15 ancil-lary reagents including the waste and water, all of which canbe added and removed at any time. Also the bulk reagentscan be replaced at any time. The computer system that hasbeen selected for the system presents an interface with intu-itive icon-driven software that relies on dual Sun Microsys-tems SPARC® II processors.

2.2.3. The system offers extensive flexibility

• The sample can be loaded directly from the track with apositive identification.

• Up to 180 samples can be onboard when the instrumentis fully loaded.

• The volume for assay controls vary between 10 and 150�land an unlimited number of controls per test can be de-fined with additionally up to 50 tests per control. The in-strument has the ability to store up to 300 data points foreach combination of test and control.

The sample loading is very flexible as samples can beintroduced to the front of the system or from an automationtrack in the back. A stand-alone operation is possible becausethe instrument functions independently of track even whenthe track is not operational. The instrument has been designfor universal applications, thus, allowing its integration toany currently existing laboratory automation system withoutrobotic interfaces.

2.2.4. The system offers robust infectious disease testing

• Disposable sample tips are used to collect and deliver thesample, thus preventing sample carryover.

• A unique process for the verification of sample and reagentdelivery as well as for dispense-integrity is operational onthe instrument.

• The verification of sample aspiration is performed bymeans of a patented air pressure circuit which at the sametime◦ monitors tip pick up and removal;◦ provides liquid level sense detection and clot detection;

and◦ verifies delivery of sample.

• The verification of sample delivery takes place by mea-suring the diluter movement to verify the volume of eachsample.

• A circuitry for bubble detection and volume check ensuresreagent aspiration and dispense-integrity. An additionalvolume check for each reagent dispense is carried out byverifying the diluter movement.

• All reagent probes are washed inside and out after eachreagent delivery to prevent contamination and carryover.

• When the samples are in the queue the clot detection andclot management are active.

• All dilutions and repeats are performed automatically.

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2.2.5. The system offers maximal performanceThe assays for infectious disease testing represent maxi-

mized system performance as a result of

• utilization of multiple solid phases in a single assay (withresultant ability to include multiple epitopes for sensitivityand assay optimization);

• flexible assay protocols with variable incubation times andon-board pre-treatment and dilutions;

• utilization of many types of particles (e.g., para-magnetic)and coupling chemistries (flexibility and reagent optimiza-tion);

• very low background signal (sensitivity and specificity);• use of direct chemiluminescent detection with acridinium

esters with multiple tracers per assay;• the proprietary acridinium esters (e.g., DMAE-NHS and

NSP-DMAE) generate high quantum yields, are easyto couple to both large and small molecules, and dueto their small size, permit maximal diffusion rates andcause virtually no steric hindrance in immunochemistryreactions.

3. Conclusions

Automation in infectious disease testing has experienceda rapid progress because of increased market demands,which the diagnostics industry has been able to satisfythrough the availability of better analytical platforms. Thesemodern systems feature a blend of engineering, immuno-chemical, and software technologies, featuring recombi-nant antigens, high specificity and avidity monoclonalantibodies, low non-specific binding paramagnetic parti-cles, advanced robotics, and automated computer-drivenprocesses.

The ADVIA Centaur immunoassay system represents anoptimal automated analyzer for development of assays forinfectious disease due to its flexibility in assay formats andprotocols with multiple incubation steps and washes andfrom its utilization of chemiluminescent signal detectiontechnology.

Further features of the system designed with infectiousdisease in mind are the sample integrity verification/check,the use of disposable sample pipette tips, clot and clog de-tection, liquid level sensing, the reagent aspiration verifica-tion/check as well as the automatic cascade reflex testingand repeat testing. These features are coupled with the con-venience of on-the-fly loading of samples, STAT samples,all consumables, and off-loading of waste.

Automation will increasingly become a crucial mecha-nism for clinical laboratories to better cope with the growingrequest of infectious disease testing and at the same time toachieve higher productivity and cost efficiency.

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