CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

971 ESTIMATED PrEP ELIGIBILITY IN A NATIONAL SEXUAL NETWORK STUDY OF US MSM Kevin M. Weiss , Pragati Prasad, Ramya Ramaraju, Emeli J. Anderson, Samuel Jenness Emory University, Atlanta, GA, USA Background: A 2015 CDC analysis estimated that 24.7% of sexually active men who have sex with men (MSM) had indications for HIV preexposure prophylaxis (PrEP) based on 2014 US Public Health Service (USPHS) clinical practice guidelines. The USPHS revised those guidelines in 2017, with indications for MSM now targeting MSM based on four base indications: age (18+), HIV status (HIV-negative), recent sexual activity (within 6 months), sexual network configurations (not in a monogamous relationship with a HIV-negative partner); and recent behavioral risk (condomless anal intercourse (CAI) or bacterial STD diagnosis (BSTID) in last 6 months). Updated estimates of the fraction of MSM indicated for PrEP overall and stratified by demographic factors and geography are needed to optimally scale-up PrEP for MSM in the US. Methods: We conducted a national web-based study of 2176 MSM (aged 15–65 who had ever had sex with another man) between July 2017 – February 2018. We estimated the proportion of MSMmeeting USPHS-recommended indications for PrEP using the CDC analysis denominator: adult, HIV-negative MSM sexually active in the prior year. Results: Of 1632 MSM (75%) comprising the CDC denominator, 46.1% (95% CI: 43.7, 48.6) met USPHS indications for PrEP, with percentages consistent across US census regions. Younger MSM (ages 15–24) were least likely to meet PrEP indications: 34.9%. PrEP eligibility varied by race/ethnicity (Black: 51.2%, White 46.3%, Hispanic: 47.1%, Other: 40.4%). Among individuals meeting USPHS PrEP indications, 80.5%were indicated due to recent CAI, 1.9%were indicated due to a recent BSTID, and 17.7%met both indications (CAI and BSTID). Conclusion: Estimated percentages of MSMmeeting indications for PrEP exceeded the previous CDC estimate across race/ethnicity, age, and census regions, with nearly one-half of adult, sexually active, HIV-negative MSM exhibiting indications for PrEP. These differences may reflect a combination of the 2017 changes to USPHS guidelines, increasing risky sexual behavior among US MSM, and rising incidence (and therefore diagnoses) of STIs across the US. This study suggests, given current guidelines for PrEP indications, that a lower fraction of eligible MSMmay be receiving PrEP than previously estimated. Additional age- and race/ethnicity-based considerations for PrEP indications may be needed to address rising the higher prevalence of recent STI diagnoses observed among younger and minority MSM in this study and rising HIV case counts in these populations.

of Chlamydia trachomatis (CT) and Trichomonas vaginalis (TV) co-infection that has been shown to increase susceptibility to SHIV. Methods: Adult pig-tailed macaques were inoculated with CT and TV every 3 weeks to maintain infection. Their infection status was monitored with the APTIMA Combo 2 assay. The animals were untreated (n=5) or received CAB-LA intramuscular injections (n=6; 50mg/kg) 7 days prior to the start of biweekly SHIV intravaginal challenge series, and then every 4 weeks during virus exposures. Plasma viral RNA levels were measured by RT-PCR. Drug levels were measured using liquid chromatography coupled with tandemmass spectrometry with a lower quantification limit of 1 and 10 ng/mL for biopsies/ swabs and plasma, respectively. The log-rank test was used to compare the survival distribution between untreated animals and those receiving CAB-LA. Results: STI infections were maintained in all 11 animals during the entire study. The 6 drug-treated STI-infected animals remained protected after 14 SHIV exposures while all untreated animals became SHIV-infected (p<0.0001). Infection in the untreated animals (median=2 [range: 1-10] virus exposures) was seen earlier than in historical STI-naïve controls (median=4 [range: 2-8] virus exposures; p=0.008), demonstrating further that CT and TV infections increase the risk of SHIV acquisition. CAB-LA concentrations in plasma were maintained above 664ng/mL, four times the PA-IC90 (mean 2254ng/mL; range: 892-4280ng/mL). Conclusion: Despite being a single drug agent, CAB-LA at a clinical dose maintained full and durable efficacy against vaginal SHIV acquisition in macaques continuously infected with CT and TV. The data from this model reflect robust protection that may not be sensitive to vaginal inflammation. 970 ANTI-Α4Β7 ANTIBODY REDUCES MACAQUE VIREMIA BUT NOT RISK OF RECTAL SHIV ACQUISITION Chunxia Zhao 1 , Roopa Luthra 1 , Michele Daly 1 , Dawn Little 1 , Gerardo Garcia- Lerma 1 , Debra R. Adams 1 , Jining Zhang 1 , Aftab A. Ansari 2 , Siddappa N. Byrareddy 3 , Janet McNicholl 1 , Sundaram Ajay Vishwanathan 1 1 CDC, Atlanta, GA, USA, 2 Emory University, Atlanta, GA, USA, 3 University of Nebraska Medical Center, Omaha, NE, USA Background: It has been shown that the simianized anti-α4β7 monoclonal antibody (mAb) partially protects against vaginal simian immunodeficiency virus (SIV) acquisition. We hypothesized that infusion of anti-α4β7 mAb in rhesus macaques prior to and during repeat low-dose rectal simian-human immunodeficiency virus (SHIV) exposures would offer significant protection against viral acquisition and suppress viremia in the gut-associated lymphoid tissues. Methods: Adult rhesus macaques (n=6) received intravenous infusions of anti-α4β7 mAb (50mg/kg) 3 days prior to the first of the weekly SHIV162p3 challenges (50TCID50). The antibody dose and timing of first challenge were chosen to be identical to the prior study showing vaginal protection. Plasma viral RNA was measured by RT-PCR. Total SHIV DNA in PBMCs was quantitated using a double-stranded primer assay. Plasma and mucosal secretions were tested by ELISA for levels of anti-α4β7 mAb and rhesus anti-rhesus antibodies (RARA). CD4 levels were measured in PBMCs and rectal biopsies by flow cytometry. Results: All anti-α4β7-treated animals became SHIV infected after a median of 2 challenges. Peak viral loads in anti-α4β7-treated animals were significantly lower (6.1 versus 7.8 log copies/ml; p=0.0023; unpaired 2-tailed t-test) than historical controls. In 4/6 anti-α4β7-treated animals, plasma viremia was rapidly controlled to <3000 copies/ml at 9 weeks; these four also had lower peak viremia compared to the other 2 (5.8 versus 7.1 log copies/ml; p=0.113; Mann- Whitney test). Average CD4 levels post-infection were significantly higher in the 4 animals that controlled versus the other two (p=0.01, rectum; p<0.0001, PBMCs). In all anti-α4β7-treated animals, total SHIV DNA levels in PBMCs began to decline 2 weeks post-peak viremia and were below the level of detection by week 4. RARA levels were close to baseline in all animals at time of challenge, and did not correlate with weeks to infection or viremia. Conclusion: Infusion with anti-α4β7 mAb prior to SHIV exposures resulted in improved control of post-infection viremia in plasma and PBMCs. The antibody did not protect from rectal acquisition. Differences between rectal and vaginal compartments may influence anti-α4β7 antibody distribution and effects, and therefore differently modulate SIV/SHIV acquisition.

Poster Abstracts

972 CHANGES IN HIV PrEP AWARENESS AND USE AMONG MEN WHO HAVE SEX WITH MEN, 2014 VS 2017 Teresa Finlayson 1 , Susan Cha 1 , Damian Denson 1 , Lindsay Trujillo 2 , Mingjing xia 3 , Joseph Prejean 1 , Cyprian Wejnert 1 , for the NHBS Study Group 1 CDC, Atlanta, GA, USA, 2 Oak Ridge Institute for Science and Education, Atlanta, GA, USA, 3 ICF International, Atlanta, GA, USA Background: The US Food and Drug Administration (FDA) approved the first drug for daily HIV pre-exposure prophylaxis (PrEP) use in 2012. Subsequent to FDA approval, efforts have been made to raise awareness and use of HIV PrEP among men who have sex with men (MSM) and those who are at increased risk for acquiring HIV infection. We evaluated changes in PrEP awareness and use

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