CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Conclusions: As the only platform of algorithms that can reliably infer the tropism of the major global HIV-1 subtypes, PhenoSeq has the potential to inform the appropriate use of maraviroc and future CCR5 blocking drugs in regions of the world where non-B HIV-1 predominates, and which are burdened the most by the HIV-1 pandemic. 634 Accuracy of Re-Reading HIV Rapid Tests and the Effect of Prolonged High Temperature AugustineT. Choko 1 ; DeusThindwa 1 ; Peter MacPherson 2 ; Rodrick Sambakunsi 1 ; Aaron Mdolo 1 ; Kondwani Chiumya 1 ; Owen Malema 3 ; Simon Makombe 4 ; Emily L.Webb 6 ; Elizabeth L. Corbett 6 1 Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi; 2 University of Liverpool, Liverpool, United Kingdom; 3 Ministry of Health, Blantyre, Malawi; 4 Ministry of Health, Lilongwe, Malawi; 5 London School of Hygiene and Tropical Medicine, London, United Kingdom; 6 London School of Hygiene and Tropical Medicine, London, United Kingdom Background: Accurate rapid diagnostic test (RDT) results are critical to HIV testing, care and prevention services. However, suboptimal storage at ambient temperatures above manufacturer-recommendation is common in sub-Saharan Africa. Re-reading of used test kits can provide valuable programmatic quality-assurance, and “late” reading is also commonly reported following HIV self-testing. We evaluated the effects of prolonged exposure to high temperatures on both initial accuracy, and reproducibility of late reads. Methods: A cross-sectional diagnostic evaluation in Blantyre, Malawi. Consenting participants attending HIV testing services had parallel testing with 3 RDTs (OraQuick (oral), Determine 1/2™, Alere, Waltham, USA and Uni-Gold™ Recombigen ® HIV, Trinity Biotech, Bray, Ireland): a) preincubated for 28 days at 37 s C as intact packages and b) the same 3 RDTs stored under optimal conditions (6 tests in total). All 6 kits were read by the study nurse at the recommended time, and then again by a laboratory technician on the same day and monthly for 12 months (although with reference to previous results). Optimally stored Uni-Gold/Determine/SD Bioline were used for the gold standard. Results: Of 378 participants, 198 (53.4%) were male with median age 31 years (IQR 25-40). Compared to gold standard, sensitivity for normal and high temperature OraQuick, Determine and Uni-Gold are shown in the table below. All but 6 participants had concordant results from each of the 6 kits, with no discernable effect on accuracy from preincubation. One participant was positive on both OraQuick (optimal) and Determine (optimal), but negative on the other RDTs, and was classified as HIV-negative. A further 5 participants had false-negative results on one or more RDTs. Notably, 108 (28.6%) reported being on antiretroviral treatment (ART). Over 12 months of re-reading used OraQuick kits; 1 (0.3%) in both optimal-stored and high temperature groups changed from negative to positive (different clients). In both cases participants were known to be on ART.

Conclusions: This study showed that rapid diagnostic HIV test kits stored at prolonged high temperature did not appreciably affect diagnostic performance. Repeated reading of OraQuick kits up to 12 months after testing appears to be highly reproducible, although not recommended by the manufacturer. Clients seeking retesting while on ART maybe an increasing common cause of inaccuracy in HTC clinics. 635 Analysis of False Negative HIV Tests Based on Oral Fluid in 3 Clinical Trials Marcel E. Curlin 1 ; MichaelT. Martin 1 ;Wanna Leelawiwat 2 ; Roman Gvetadze 1 ; Charles Rose 1 ; Sarika Pattanasin 2 ; Richard Niska 1 ;Timothy Holtz 1 ; Kachit Choopanya 3 ; Janet McNicholl 1 1 US Centers for Disease Control and Prevention, Apo, US; 2 Thailand Ministry of Public Health–Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; 3 Bangkok Tenofovir Study Group, Bangkok, Thailand Background: The OraQuick Advance Rapid HIV-1/2 Antibody Test (OraSure, Bethlehem, PA) is a non-invasive, point-of-care, rapid HIV test capable of detecting HIV-specific antibodies in blood and oral fluid. The test is convenient and promises to increase HIV testing in at-risk populations. However, concerns regarding test sensitivity in oral fluid suggest that OraQuick Oral fluid (OQOF) test performance should be further studied before relying on this assay in clinical trials and other contexts where negative predictive value may be lower than in typical clinical settings. Methods: We examined OQOF performance among all seroconverting participants in the Botswana Tenofovir PrEP Study (TDF2), the Bangkok Tenofovir Study, and the Bangkok Men Who Have Sex With Men Cohort Study, three longitudinal clinical studies conducted in Botswana and Thailand. OQOF screening test results were compared with estimated time of infection determined by enzyme immunoassay and/or nucleic acid amplification tests on stored blood samples. We used generalized estimating equations log-binomial regression to examine the association between FN OQOF test results and participant age and gender, time since infection, viral subtype, plasma viral load (PVL), exposure to antiretroviral drugs, test operator, clinical site, and test lot. Results: In total, we identified 208 false negative (FN) OQOF test results among 81 of 290 (28%) seroconverters (all studies). Median estimated OQOF reactivity delay time was 98 days (range 14-547 days). FN tests were correlated with testing within 90 days of estimated date of infection, randomization to ARV-based pre-exposure prophylaxis, lower plasma viral loads, individual test operators, and specific testing sites, in one or more studies ( p < 0.05). Age, gender, HIV subtype and test kit lot were not associated with FN tests ( p > 0.05). Conclusions: Failure of OQOF to detect HIV-1 infection was frequently observed in these three studies. Factors contributing to FN OQOF test results include recent infection, exposure to antiretroviral agents, low PVL, and operator-related factors. In the context of clinical trials, where a FN test may be more likely than in routine clinical settings, negative screening tests based on oral fluid should be confirmed by laboratory-based tests in blood, and measures should be taken to ensure proper training and ongoing quality assurance.

Poster Abstracts

399

CROI 2015