CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

specific FRRs increased above 1% at ODn thresholds above 2.0, resulting in poorer precision, as shown in the figure. In scenarios I and II, precision was best at ODn≤1.25, and in III at ODn≤2.25. Conclusion: MDRI and FRR vary by substantially HIV-1 subtype and sex. Optimal performance was achieved at ODn thresholds from 1.0-2.5. RITA properties depend strongly on population-level subtype and sex distributions.

of HIV infection, accounting for repeat sampling from the same individuals. An independent sample set from the same cohort was used to validate results (72 samples from 32 women infected 84 days to 9.1 years). Results: We identified 309 peptides that had a significant association between Ab binding and duration of infection (p<0.05 after adjusting for multiple comparisons); 266 peptides had increasing Ab binding over time and 43 peptides had decreasing Ab binding over time. Four peptides were selected for further analysis (two with increased binding: in gp120 and gp41; two with decreased binding: in gag and pol). The binding scores for these four peptides were combined in a simple, unweighted, linear model to estimate the duration of infection. This estimate was highly correlated with the observed (true) duration of infection (p <3 x 10 -36 in the independent sample set). The predictive value of the 4-peptide «serosignature» did not appear to be impacted by low viral load, low CD4 cell count, or HIV subtype. We also demonstrated that peptide engineering could be used to improve the association of Ab binding and duration of HIV infection. Conclusion: Deep profiling of the antibody response to HIV infection identified novel peptide biomarkers for the duration of HIV infection. Peptides identified using this approach could be incorporated into simpler, high-throughput assays for cross-sectional HIV incidence estimation and other applications. 944 INCIDENCE OF HIV IN A NATIONAL COHORT RECEIVING PREEXPOSURE PROPHYLAXIS Puja Van Epps 1 , Brigid M. Wilson 1 , Will Garner 2 , Lauren Beste 3 , Marissa M. Maier 4 , Michael Ohl 5 1 Case Western Reserve University, Cleveland, OH, USA, 2 University Hospitals Cleveland Medical Center, Cleveland, OH, USA, 3 VA Puget Sound Health Care System, Seattle, WA, USA, 4 VA Portland Health Care System, Portland, OR, USA, 5 University of Iowa, Iowa City, IA, USA Background: Once daily tenofovir disoproxil fumarate/emtricitabine (TDF/ FTC) was FDA approved for pre-exposure prophylaxis (PrEP) for HIV prevention in July 2012. Veterans Health Administration (VHA) is the largest single provider of HIV care nationally thus offers a unique opportunity to examine PrEP in a large cohort. We aimed to determine the incidence of HIV infection in patients initiating PrEP and to describe relationships between HIV cases and patterns of PrEP use. Methods: We conducted a retrospective cohort study among patients initiating PrEP in VHA between July 2012 and April 2016 using national VHA data and a previously described algorithm. We identified cases of HIV infection after PrEP initiation based on lab data (i.e. HIV serology and viral load results). We defined the date of PrEP initiation by date of first TDF/FTC fill. Adherence measure was calculated by determining the number of days with TDF/FTC in possession between the first day of the first TDF/FTC fill and the first day of the last fill in the year and dividing this by the number of days in this interval. We defined days without pills as numbers of days without TDF/FTC in possession prior to send date of first positive HIV test. To calculate HIV incidence, we considered the total patient time from first fill to the date of the last pill of the last fill available. We used chart review to determine patient-reported PrEP use around time of diagnosis. Results: We identified 825 unique patients initiating PrEP with a median observed PrEP duration of 8 months and a cohort total of 736.6 years. Our cohort was composed of 97%men, 67%white patients, and with a mean age of 41 years. Two HIV infections occurred during active PrEP use for an incidence of 0.3 cases per 100 person years (Poisson exact 95% CI = (0.03, 0.98)). Both patients were infected with viruses containing the M184V mutation and had perfect adherence based on fill data. Four additional cases were observed in this cohort, diagnosed during periods without PrEP. Among these 4, days without pills ranged from 4 to 162 days. Conclusion: HIV infection was rare in this nationwide cohort of PrEP users. Most HIV infections occurred off PrEP, emphasizing the need for interventions to improve PrEP persistence in persons with ongoing risk. 945 HIV-1 INCIDENCE AND RISK FACTORS FOR ACQUISITION AMONG KENYAN MSMWITH ACCESS TO PrEP Elizabeth Wahome 1 , Susan M. Graham 2 , Alexander N. Thiong’o 1 , Khamisi Mohamed 1 , Tony H. Oduor 1 , Evans Gichuru 1 , John Mwambi 1 , Eduard Sanders 1

Poster Abstracts

943 ANTIBODY PROFILING IDENTIFIES NOVEL BIOMARKERS FOR DURATION OF HIV INFECTION Oliver Laeyendecker 1 , Kai Kammers 1 , Athena Chen 2 , Mariya V. Sivay 1 , Brandon Sie 1 , Tiezheng Yuan 1 , Divya Mohan 1 , Daniel Wansley 1 , Tomasz Kula 3 , Charles S. Morrison 4 , Stephen Elledge 3 , Ron Brookmeyer 5 , Ingo Ruczinski 2 , H. Benjamin Larman 1 , Susan H. Eshleman 1 1 Johns Hopkins University School of Medicine, Baltimore, MD, USA, 2 Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA, 3 Harvard University, Boston, MA, USA, 4 FHI 360, Durham, NC, USA, 5 University of California Los Angeles, Los Angeles, CA, USA Background: Improved methods for cross-sectional HIV incidence estimation are needed for surveillance of the epidemic and for evaluating the impact of HIV prevention interventions. We used a massively-multiplexed system, VirScan, to identify novel biomarkers for estimating the duration of HIV infection. This system uses phage display immunoprecipitation sequencing to quantify antibody (Ab) binding to >3,300 peptides spanning the HIV genome. Methods: We analyzed 403 samples from 57 African women with known duration of infection (14 days to 8.7 years). Ab binding to each peptide in the VirScan library was quantified, and peptides with the strongest association of Ab binding with duration of HIV infection were identified. We used generalized estimating equations to analyze the association of Ab binding with duration

CROI 2019 369