CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

Methods: We developed and validated an HIV-2 total nucleic acid (TNA) test using the Abbott m2000 platform. Amplification of human DNA and internal control RNA was used to assess for sample quality and assay inhibitors. Assay sensitivity was evaluated by testing known copies of HIV-2 plasmid DNA mixed with 1 million PBMC. Matched plasma and PBMC samples were collected from 25 HIV-1, 30 HIV-2, 8 HIV-1/2 dual-seropositive and 25 HIV-seronegative participants. Diagnostic performance was evaluated by comparing the outcome of the HIV-2 TNA assay with the results obtained by the Abbott HIV Ag/Ab Combo assay (Combo) and the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test. Results: The assay sensitivity was 26 TNA copies/million cells (95% CI, 18-55 copies/million cells). Thirty of thirty (100%; 95%CI lower bound 88.4%) PBMC samples from HIV-2 seropositive participants tested positive for HIV-2 TNA, including 21 samples from participants with undetectable HIV-2 plasma RNA. All thirty matching plasma samples from the HIV-2 TNA-positive participants were reactive for Combo. Among these thirty Combo-reactive samples, twenty nine were confirmed HIV-2 Ab positive and one was nonreactive by Multispot. Plasma samples from 50 HIV-2 TNA-negative individuals were confirmed non-reactive for HIV-2 Ab. Thus, the overall agreement between the HIV-2 TNA assay and the combined results of the immunoassays was 98.8% (79 of 80). The TNA assay also detected HIV-2 in 7/8 PBMC samples from HIV-1/-2 dually infected participants with undifferentiated Multispot and Geenius HIV-1/HIV-2 assays seroreactivity. Conclusion: Our HIV-2 TNA assay detected HIV-2 in PBMC from serologically HIV-2 reactive, HIV indeterminate, and HIV undifferentiated individuals with undetectable plasma HIV-2 RNA, and is suitable for confirming HIV-2 infection in the CDC HIV testing algorithm. 509 EVALUATION OF FDA-APPROVED RAPID HIV TESTS FOR LABORATORY DIAGNOSIS OF HIV INFECTION Kevin P. Delaney , Steven Ethridge, Hongwei Jia, Silvina Masciotra, Laura Wesolowski CDC, Atlanta, GA, USA Background: The 2014 revised CDC/APHL Guidelines for Laboratory Diagnosis of HIV infection recommend that reactive antigen/antibody (ag/ab) screening tests be followed by a supplemental antibody test capable of differentiating HIV-1 from HIV-2. However, there is currently only one such supplemental test approved and available for use in the United States. We investigated the performance of other FDA-approved single-use HIV tests when used in this step in an HIV testing algorithm. Methods: Stored plasma or serum specimens from a study conducted in Los Angeles, California from 2003-2007 were used in this analysis. 707 specimens previously reactive on at least one FDA-approved ag/ab screening test, from 5,470 persons screened for HIV and 403 persons recruited with known HIV infection, were tested with 8 FDA-approved rapid HIV tests. We compared these test results with those from the Geenius HIV-1/HIV-2 differentiation assay. As in the guidelines, specimens with non-reactive results on the supplemental test after a reactive ag/ab test were categorized as HIV-infected or false-reactive on the screening test based on the Aptima HIV-1 qualitative RNA test result. Results: All FDA-approved rapid tests performed similarly to the Geenius assay in terms of ability to differentiate true infection from false-reactive results for specimens from persons without early HIV infection (Table 1). The Insti HIV-1/HIV-2 antibody test and Determine HIV-1/HIV-2 Combo correctly identified 5/8 early infection specimens; all had been non-reactive using Geenius and all other rapid tests. However, these two tests also returned reactive results in 3-4 specimens (<1/1000 screened) that were HIV-1 Western blot and Aptima negative. Conclusion: All FDA-approved rapid tests could serve the role of a supplemental test in the HIV-1 diagnostic algorithm. Although they don’t differentiate HIV-1 from HIV-2, HIV-2 remains rare in the US and would be identified when a quantitative HIV-1 viral load was performed at HIV care initiation. Likewise, the few false-reactive rapid tests could also be resolved during clinical follow-up. Factors such as speed with which results can be returned and care initiated and simplicity of both testing and result reporting make these other rapid tests good alternatives for the second step in the HIV diagnostic algorithm. These data suggest other rapid tests should be considered as options for this step in future updates to laboratory testing algorithm guidelines.

Poster and Themed Discussion Abstracts

510 PERFORMANCE OF DRIED BLOOD SPOTS AS A SAMPLE TYPE FOR HIV AG/AB COMBO ASSAY Vera Holzmayer , Kelly Coller, Jill Fuhrman, Mary Rodgers, Gavin Cloherty Abbott Labs, Abbott Park, IL, USA Background: In resource limited settings, the use of Dried Blood Spots (DBS) for HIV viral diagnosis and monitoring has become a necessity for improved patient management. In this study, we evaluated the performance of the Abbott ARCHITECT HIV Ag/Ab Combo assay using DBS samples. Methods: Whole blood (WB) frommatched pairs of HIV infected plasma/WB samples was spotted on the Whatman 903 cards, dried overnight, eluted, and tested with HIV Ag/ Ab Combo assay. Reproducibility of the test results was assessed using triplicates of the 12mm and 6mm DBS from four HIV samples. DBS stability was evaluated on samples

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