CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Conclusions: Rank-based deconvolution based on RCMs can substantially increase the capacity of comprehensive VL monitoring, suggesting its potential utility in RLS.

WEDNESDAY, FEBRUARY 25, 2015 Session P-M2 Poster Session

Poster Hall

2:30 pm– 4:00 pm Comparison of HIV Incidence Assays 620 Evaluation of Determine TM HIV-1/2 Ag/Ab Combo in the Context of Acute HIV Screening Silvina Masciotra 1 ; S. Michele Owen 1 ;Wei Luo 1 ; EmilyWestheimer 2 ; Stephanie Cohen 3 ; Laura Hall 4 ; Cindy L. Gay 5 ; Philip J. Peters 1 1 US Centers for Disease Control and Prevention (CDC), Atlanta, GA, US; 2 New York City Department of Health and Mental Hygiene, New York, NY, US; 3 San Francisco Department of Public Health, San Francisco, CA, US; 4 ICF International, Atlanta, GA, US; 5 University of North Carolina, Chapel Hill, NC, US Background: Determine TM HIV-1/2 Ag/Ab Combo (DC) is an FDA-approved 4 th generation rapid test that can distinguish HIV antigen and antibody reactivity, but performance in the new HIV diagnostic algorithm has not been evaluated. Data on the performance of DC on whole blood from individuals in early phases of infection are limited. We evaluated the performance of DC with plasma and whole blood. Methods: We tested two sets of samples with DC and compared results to previous data from the APTIMA RNA assay (Aptima), Abbott ARCHITECT (ARC), Multispot HIV-1/HIV-2 rapid test (MS), and OraQuick ADVANCE (OQ). The sets included a subset of 178 plasma samples collected in the STOP study, a multi-site, prospective study evaluating methods to detect acute infection and 54 sequential plasma samples from 12 seroconverters to which washed red blood cells were added to simulate whole blood at 40% hematocrit. The number of DC-reactive samples and days after the first positive Aptima were calculated for samples from seroconverters. Statistical analysis was done using the McNemar’s test. Results: Among the STOP specimens, the 4 th generation lab-based ARC detected 19 more infections than DC ( p=0.0001 ) (Table). Of 107 ARC-positive samples, DC detected 52.6% of the acute infections (p<0.0001) and 98.6% of the established infections (p=1.00). DC also identified 93.3% of HIV established infections in plasma that were not detected with OQ using whole blood at the screening sites ( p=0.0001 ). Among seroconverters, of 54 Aptima-positive/ARC-positive/MS-neg or –indeterminate samples, DC was reactive in 52 (96.3%) of plasma and 36 (66.6%) of whole blood ( p=0.003 ) and OQ was reactive in 14 (26%) in plasma. The reactivity of DC in whole blood was 17 Ag+, 2 Ag+Ab+, and 17 Ab+. Whole blood reactivity was delayed in 7/12 seroconverters compared with plasma. Overall, the median delay in reactivity with whole blood compared to plasma was two days.

Poster Abstracts

Conclusions: DC used with plasma detected fewer specimens with acute HIV infection compared to an instrumented lab-based 4 th generation as ARC. DC became reactive later with whole blood than with plasma, but earlier than OQ used with plasma, which may be partially due to detection of antigen in whole blood. Thus, if CLIA-waived, DC would likely represent an advantage over other rapid tests in detecting infections earlier in settings where lab-based testing is not feasible. 621 Performance of the Geenius HIV-1/HIV-2 Assay in the CDC HIV Testing Algorithm Kevin P. Delaney ; Steven Ethridge; Laura G.Wesolowski; MIchele Owen; Bernard M. Branson US Centers for Disease Control and Prevention (CDC), Atlanta, GA, US Background: CDC recently released new guidelines for laboratory diagnosis of HIV infection in the United States (the “CDC algorithm”), which recommends use of an assay that differentiates HIV-1 from HIV-2 after a reactive HIV-1/HIV-2 screening test. Currently only the Multispot HIV-1/HIV-2 differentiation test (MS) is FDA-approved for this use. A new test, the Geenius HIV-1/HIV-2 Supplemental assay (Geenius), has been proposed to replace MS. Methods: We evaluated Geenius with a panel of specimens previously tested with FDA-approved screening tests, MS and the Aptima RNA assay (NAT) and classified by the CDC algorithm. The 873 specimens included 658 classified as HIV-1 by the CDC algorithm (HIV1+), 8 classified as acute HIV-1 infections (acute), and 207 specimens with reactive results on at least one HIV-1/HIV-2 screening test identified from 4500 previously collected specimens classified as negative (HIV-): 176 with a reactive HIV screening test result other than MS, 5 reactive on another screening test and MS, and 26 with only a reactive MS screening test result. We compared Geenius results with those from the CDC algorithm and MS.

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CROI 2015