CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Results: Semen from HIV infected men enhanced HIV infectivity (mean 10.8-fold, range from 0- to >35-fold enhancement). Levels of endogenous amyloidogenic SEM were correlated with the infectivity-enhancing activity of semen samples (r=0.48;p<.0001). For individual subjects with longitudinal samples, levels of both infectivity enhancement and SEM tended to be similar over time (intraclass correlations (ICCs) for infectivity enhancement 0.33, SEM 0.49, semen VL 0.42). Infectivity enhancing activity of semen had little association with ART naïve semen VL (r=-0.08). With interruption of ART (baseline semen VL<200 cp/mL in 18/20 subjects), there was no systematic increase in either infectivity enhancement (mean 18% decrease, p=0.17) or SEM (mean 13% decrease, p=0.054). Conclusions: Our results suggest that semen from HIV infected men can enhance the efficiency with which HIV infects permissive cells, in a manner that persists in men taking ART and is independent of semen VL but is directly associated with levels of amyloidogenic SEM fragments. The HIV-enhancing activities of multiple semen samples from the same individual were relatively similar, even upon ART treatment, suggesting that the HIV enhancing activity of semen can be considered an individual characteristic. Together, these

data suggest that individual semen characteristics other than HIV VL may be important factors in HIV transmission. 210 Hyaluronan Reduces HIV Infection of CD4+ T Cells and Greatly Enhances HIV Inhibition by Tenofovir Peilin Li ; Katsuya Fujimoto; Lilly Bourguignon; StevenYukl; Steven Deeks; Philipp Kaiser; Peggy Kim; Diane Havlir; Harry Lampiris; Joseph K.Wong University of California San Francisco, San Francisco, CA, US

Background: Better strategies are needed to prevent mucosal transmission of HIV. The major extracellular matrix receptorCD44, present on virion and target cells, has been reported to strongly influence viral infectivity. Topical formulations of antiviral drugs like tenofovir (TDF) are being studied in HIV prevention. We investigated how the natural ligand of CD44, hyaluronan, modulates HIV infection in vitro when used alone or with TDF. Methods: HIV stocks were produced with or without CD44. Infection of cell lines (M7 Lue, TZM-bl) and of primary CD4+ T cells were performed with or without exogenous HA, inhibitors to HA signaling through PKCa, and TDF. Infection was gauged by RLU and p24 measurements. IC50 and IC95 of TDF were calculated. Significance was tested using a T-test. Results: HA reduced HIV infectivity only when virions expressed CD44. HA inhibited HIV infection modestly and consistently in a dose dependent manner and removal of endogenous HA enhanced viral infectivity. Treatment with Gö6976, an inhibitor of PKCa, abrogated the effects of HIV to a degree similar to exogenous HA. Notably, co-treatment of cells with HA and tenofovir shifted TDF IC50 by greater than 1 log compared to TDF alone, while TDF IC95 was reduced by over 400 fold in the presence of HA. Similar findings were seen with R5 and X4 virus. HA was synergistic with the entry inhibitor T20 but to a lesser degree. Conclusions: HA interacts with CD44 on virion and cell membranes to modulate HIV infection at the early (binding, entry) and post entry steps in the viral lifecycle. We found marked enhancement of antiviral effects of TDF by HA. Manipulation of CD44-HA interactions, used alone or together with antiviral drugs, deserves further study as a novel strategy to prevent transmission. 211 Alpha-defensins increase HIV transcytosis: role in STI-mediated enhanced HIV transmission Kimyata B. Valere 1 ; Aprille Rapista 1 ; Alison Quayle 2 ;Wuyan Lu 3 ; Eliseo Eugenin 1 ;Theresa Chang 1 1 Rutgers University-New Jersey Medical School, Willingboro, NJ, US; 2 University Health Science Center, New Orleans, LA, US; 3 University of Maryland School of Medicine, Baltimore, MD, US Background: Although mucosal epithelial cells provide the first-line of defense against HIV infection, HIV can cross the genital or intestinal epithelium by transcytosis. The risk of HIV transmission is increased in individuals with Sexually Transmitted Infections (STIs). Defensins are antimicrobial peptides important for mucosal innate immunity. Alpha-defensins, including human defensin 5 (HD5) and human neutrophil defensins 1-3 (HNPs1-3), are elevated at the genital mucosa in individuals with STIs. HD5 promotes HIV infectivity and contributes to enhanced HIV infection by STIs in vitro. Unlike HD5, HNPs exhibit anti-HIV activity in vitro. However, enhanced HIV acquisition is associated with increased levels of HNPs in cervicovaginal fluid. In this study, we examined the effect of alpha-defensins on epithelial integrity and the subsequent impact on HIV transcytosis in polarized epithelial cells. Methods: Defensins were added to the apical side of polarized intestinal epithelial (Caco) cells. Transepithelial electrical resistance was measured by cellZscope to monitor epithelial permeability. Distribution of tight junction markers was observed by immunofluorescent staining of ZO-1 or occludin. To examine HIV transcytosis, HIV-1 BAL was added to the apical side of polarized epithelial cells, and HIV that crossed to the basolateral side was measured by HIV p24 ELISA. Results: HNP significantly increased epithelial permeability in a dose-dependent manner within 4 hours, suggesting transient HNP1-mediated epithelial disruption. However, HD5 at high concentrations slightly reduced TERs. Linear analogs of HNP1 and HD5 did not affect epithelial permeability, indicating that the impact of alpha-defensin on epithelial integrity is structure-dependent and not charge-dependent. Interestingly, both HD5 and HNP1 caused discontinuation and internalization of tight junction proteins in Caco cells. In agreement with their impact on epithelial permeability, HNP1, but not HD5, significantly increased HIV transcytosis in polarized intestinal epithelial cells. Conclusions: Our results demonstrated that HNP1 and HD5 displayed distinct functions in facilitating transmission of HIV. Since HNP1 can alter the integrity of the mucosal epithelium leading to increased HIV transcytosis, defensin-mediated disruption of mucosal barriers offers a window of opportunity for HIV to invade the host. Our study provides a new role of HNP1 in STI-mediated enhancement of HIV transmission. 212 The Design and Investigation of Mechanism of Novel Potent HIV-1 Entry Inhibitor SC12 Marina Tuyishime ; Simon Cocklin Drexel University College of Medicine, Philadelphia, PA, US Background: The process of HIV-1 entry is key to the replication of the virus and viral Env serves as a hot target as a first protein complex encountering the target cell. We designed a novel potent HIV-1 entry inhibitor, SC12 that binds viral Env and prevents the infection. In addition, SC12 has better predicted ADME/PK (absorption, distribution, metabolism and excretion/pharmacokinetic) properties compared to the lead chemotype in HIV-1 entry field, BMS compounds. Given the enormous potential of the small molecule entry inhibitor, SC12, we sought to investigate the mechanism of its action against HIV-1 viruses. Methods: We utilized the single-round infection assay against HIV-1 viruses pseudotyped with HIV-1 Env and AMLV Env to identify the potency and specificity of SC12. Surface Plasmon Resonance (SPR) was employed to determine the binding site of SC12 on viral Env and to investigate its potential to block sCD4-gp120 binding. We designed a novel attachment assay based on the temperature dependence of entry to determine the effect of SC12 on viral attachment and viral fusion. Results: SC12 has low nM to mid m M potency range against numerous isolates of HIV-1 clades A through D. In addition, SC12 was determined to directly bind gp120 and the gradual increase of SC12 concentration did not affect sCD4 binding to gp120. Moreover, SC12 did not block viral attachment to the cells regardless the time of the addition of the compound: before, after or at the time of the viral infection. Conclusions: We have designed a novel small molecule inhibitor that is potent against various HIV-1 isolates proposing that the binding site of SC12 is conserved throughout the clades. We did not observe a concentration-dependent competition of SC12 and sCD4 for the binding site on gp120, proposing that SC12 is not an attachment inhibitor. Moreover, at the concentration of 70nM SC12 did not affect viral attachment to the cells, however, was able to inhibit over 50% of viral infectivity. Taken together, we propose that SC12 is not

Poster Abstracts

206

CROI 2015