CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

(R2=0.91) but showing significant differences [≥0.5log, range from -0.55 to 1.07] in 12 (15.4%) of 78 cases with VL above detection limit by both assays. Most (91.7%) of 24 obtained HIV-1 sequences were unique recombinant forms (URF), with >1000 c/ml by both VL tests in all but one sample. Conclusion: POC Xpert HIV-1 assays can successfully detect and quantify URF using DBS, which can improve the EID in HIV and of ART failures in countries with highly recombinants HIV-1 strains.

Poster Abstracts

567 RELATIVE SENSITIVITIES OF 4TH AND 5TH GEN COMBO HIV AG/AB, P24 AND VIRAL LOAD ASSAYS Mars Stone 1 , John Bainbridge 2 , Ana M. Sanchez 2 , Andrea Pappas 2 , Mark M. Manak 3 , Robert Coombs 4 , M Kathleen Shriver 5 , Paul Contestable 6 , Sangeetha Vijaysri Nair 7 , David H. Wilson 8 , Martin Stengelin 9 , Gary Murphy 10 , Indira Hewlett 11 , Thomas M. Denny 2 , Michael P. Busch 1 1 Blood Systems Research Institute, San Francisco, CA, USA, 2 Duke Human Vaccine Institute, Durham, NC, USA, 3 Walter Reed Army Institute of Research, Silver Spring, MD, USA, 4 University of Washington, Seattle, WA, USA, 5 Bio-Rad, Seattle, WA, USA, 6 Ortho Clinical Diagnostics, Rochester, NY, USA, 7 Hologic Corporation, Bedford, MA, USA, 8 Quanterix Corporation, Lexington, MA, USA, 9 Meso Scale Diagnostics, LLC, Rockville, MD, USA, 10 Public Health England, London, UK, 11 FDA, Silver Spring, MD, USA Background: Detection of acute HIV infection is critical to HIV public health and diagnostics. HIV Ag/Ab combo (4th/5th gen) immunoassays have reduced the HIV diagnostic window period by enhancing detection of acute infection, but require ongoing evaluation with currently circulating diverse subtypes. Genetically and geographically diverse, well-characterized HIV clinical isolates assembled by the NIAID Supported EQAPOL (External Quality Assurance Program Oversight Laboratory) Viral Diversity Programwere used for assessment of clinical HIV diagnostic and blood screening assays. Methods: Blinded panels of 20 diverse recent HIV isolates in serial dilution (VL 106-102 virons/mL) were distributed to manufacturers and end user labs to assess relative analytic sensitivity of licensed and pre-licensed 4th/5th gen and stand-alone p24 Ag assays across diverse subtypes. Analysis of immunoassay sensitivity was benchmarked against confirmed VL measurement. Multivariable logistic regression modeling was used to estimate the limits of virus detection (LODs) for the different assays and subtypes relative to the log 10 of viral loads determined on 2 FDA-approved VL assays. Results: Qualitative assessment of 300 observations determined that the five Ag/Ab combo and stand-alone p24 assays performed similarly, with 20-40% of samples reactive. Ag/Ab combo and standard sensitivity p24 Ag assays performed within ½ log LOD of each other, illustrating similar diagnostic utility of these assays. MSD and Simoa ultrasensitive p24 Ag assays achieved dramatically increased sensitivities with 69%-99% of samples reactive. Alere and SD Bioline rapid assays performed poorly at all concentrations. Table 1 summarizes panel performance results. A single multivariable logistic regression analysis showed that the breadth of reactivity was similar among most diverse isolates with no evidence that any one FDA-approved platform performed significantly better in quantifying p24 across diverse HIV subtypes.

566 UTILITY OF POC XPERT HIV-1 TESTS FOR DETECTION-QUANTIFICATION OF COMPLEX RECOMBINANTS Marina Rubio Garrido 1 , Adolphe Ndarabu 2 , Gabriel Reina 3 , David Barquín 4 , Silvia Carlos 1 , Africa Holguin 1 1 Hospital Ramon y Cajal, Madrid, Spain, 2 Centre Hospitalier Monkole, Kinshasa, Congo, Democratic Republic of, 3 Clínica Universidad de Navarra, Pamplona, Spain, 4 Universidad de Navarra, Pamplona, Spain Background: Implementation of simple point-of-care (POC) molecular assays for early infant HIV diagnosis (EID) and viral load (VL) quantification for early treatment failure identification can improve HIV monitoring in settings with limited laboratory infrastructure. However, they should be evaluated in areas with extremely high diversity of HIV-1 variants. We analyzed the efficacy of two POC techniques for EID and VL (Cepheid Xpert HIV-1 Quali and Xpert HIV-1 VL) versus the non-POC Roche CAP/CTM Quantitative test v2.0 in dried blood samples (DBS) collected from children and adults in Kinshasa (Democratic Republic of Congo, DRC), the epicenter of the group M epidemic. Methods: From April to November of 2016, 163 DBS were collected in Monkole Hospital (Kinshasa, DRC) from 84 children (60 HIV-, 18 HIV+, 6 HIV-exposed) and 76 HIV-infected adults (66 treated, 10 naïve). HIV diagnosis was firstly performed in DRC using rapid serological tests. Using one dot, we confirmed HIV status in children (mean age 9.6 years) using Xpert Quali. We compared viraemia with Xpert VL and Roche in all HIV+, providing RNA-HIV-1 copies per dot and per plasma milliliter after considering patient´s hematocrit. HIV-1 variant was characterized by phylogeny in partial pol sequences. Results: HIV-1 infection was confirmed in 13 of 84 children by Xpert Qualy and in 71 (93.4%) of 76 adults by both Xpert VL and Roche VL, identifying false HIV+ diagnosis in DRC in 5 adults and in 5 children (range 12-158 months age), 4 of them under unnecessary ART during a mean time 35.6 months. Among the 84 HIV+ total samples, 80 (95.2%) could be detected by Xpert VL and 82 (97.6%) by Roche VL. Detectable viraemia with Xpert VL vs. Roche VL (>40 vs. >20 c/dot or >936-1078 vs. >468-539 c/ml plasma depending on hematocrit) was observed in 12 (92.3%) HIV+ children by both assays and in 53 (74.6%) or 52 (73.2%) HIV+ adults by Xpert or Roche, respectively. VL in 14/17 samples was below Xpert/ Roche detection limit. A high correlation was observed among both VL assays

CROI 2018 208