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Evaluation of the Bio-Rad Geenius HIV-1/2 test as a confirmatory assay
© Montesinos et al; licensee BioMed Central Ltd. 2014
- Published: 23 May 2014
HIV testing algorithms include a supplemental assay to confirm and differentiate HIV-1 and HIV-2 on repeated reactive samples by a 4th generation EIA screening test (EIA). In this study we evaluate the recently CE-marked Bio-Rad Geenius HIV1/2 (Geenius) confirmatory assay, a single use immunochromatographic test, in comparison with the MP Diagnostic HIV Blot 2.2 (WB).
A total of 161 serum samples were tested by Geenius test: 72 nonreactive samples by EIA (Liaison XL Murex and/or VIDAS bioMérieux), 8 indeterminate samples by WB confirmed negative after follow up, 5 low reactive samples by EIA negative by WB and confirmed negative after follow up, 44 HIV-1 reactive samples by EIA and WB, 5 HIV-2 reactive samples, 1 HIV-1/HIV-2 co-infection sample, 15 HIV-1 non-B subtype samples (8 CRF02, 1 CRF01, 1 CRF11, 1 CRF15, 2 subtype G, 1 subtype F1, 1 subtype C) and 11 confirmed HIV-1 early seroconversion samples. The samples were tested according to the manufacturer’s guidelines. Geenius cassettes were read and interpreted by an automated reader utilizing a proprietary algorithm. The diagnostic performance and the quality management of the test were analyzed.
Overall sensitivity for Geenius assay was 92%. Five of 11 early seroconversion samples were tested positive, 4 negative and 2 indeterminate. The overall sensitivity of WB was 88%. After excluding early seroconversion samples, the sensitivity reaches 100% for both assays. All HIV-1 non-B subtype samples were tested positive. The ability to differentiate HIV-1 and HIV-2 was as follow: 2 out of the 5 HIV-2 reactive samples were tested positive HIV-2, 2 positive HIV-2 with HIV-1 cross reaction, and 1 HIV positive untypable. The co-infection HIV-1/HIV-2 sample was tested HIV positive untypable. The overall specificity for the Geenius assay was 96%. All 5 low reactive samples by EIA, negative by WB were tested negative by Geenius. Two out of the 8 indeterminate samples by WB confirmed negative were tested indeterminate and one invalid, the other 6 were negative. After excluding these last 13 samples, the specificity of Geenius assay reached 100%. In comparison with WB, the Geenius assay is markedly less time consuming (<30 minutes), allows full traceability, automatic reading and interpretation.
The Bio-Rad Geenius HIV1/2 confirmatory system represents a reliable alternative to other confirmatory assays in HIV testing algorithms and provides clear improvement in quality management.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.