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J Clin Virol. 2019 Feb;111:24-28. doi: 10.1016/j.jcv.2018.12.006. Epub 2018 Dec 19.

Performance evaluation of the Bio-Rad Geenius HIV 1/2 supplemental assay.

Author information

1
Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, United States.
2
Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, United States; Oak Ridge Institute for Science and Education, United States.
3
University of North Carolina, Chapel Hill, NC, United States.
4
New York City Department of Health & Mental Hygiene, New York City, NY, United States.
5
San Francisco Department of Public Health, San Francisco, CA, United States.
6
Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, United States. Electronic address: svm6@cdc.gov.

Abstract

BACKGROUND:

In the US, the HIV diagnostic algorithm for laboratory settings recommends the use of an HIV-1/HIV-2 differentiation supplemental assay after an initial reactive antigen/antibody (Ag/Ab) assay result. Since the discontinuation of the Multispot HIV-1/HIV-2 Rapid Test (MS), the Geenius HIV-1/2 Supplemental assay (Geenius) is the only FDA-approved supplemental differentiation test.

OBJECTIVE:

We compared the performance of Geenius to MS and Western Blot (WB).

STUDY DESIGN:

The relative seroconversion plasma reactivity of Geenius and MS was assessed using a 50% cumulative frequency analysis from 17 HIV-1 seroconverters. In addition, previously characterized plasma specimens, 186 HIV-1 positive, 100 HIV-2 positive, and 93 Ag/Ab-positive/HIV-1 RNA-negative, were tested with Geenius v1.1 software. McNemar's test was used for paired comparison analysis. A subset of 48 specimens were retested with the upgraded Geenius v1.3 software.

RESULTS:

In HIV-1 seroconverters, the relative seroconversion reactivity was 2.5 and 2 days before the first positive HIV-1 WB for Geenius and MS, respectively. In HIV-1 positive samples, Geenius performed similarly to HIV-1 WB (p=0.1687) and MS (p=0.8312). In HIV-2 positive samples, Geenius underperformed compared to HIV-2 WB (p=0.0005) and MS (p=0.0012). When using the upgraded software among the HIV-1 positive and Ag/Ab-reactive/HIV-1 RNA-negative samples, gp140 reactivity decreased without affecting characterization of HIV-2 samples.

CONCLUSIONS:

With HIV-1 samples, Geenius, WB and MS performance was similar as supplemental tests. The updated Geenius software reduced false gp140 reactivity, but had no impact on identifying true HIV-2 infections. Further evaluation will assess the impact of the Geenius software update on final diagnostic interpretations.

KEYWORDS:

Confirmatory tests; Geenius; HIV diagnostics; Multispot; Supplemental tests; Western blot

PMID:
30594702
DOI:
10.1016/j.jcv.2018.12.006

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