CROI 2016 Abstract eBook

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Poster Abstracts

C1+KIR2DS2+, and 5.4 vs 4.7 log copies/ml (p=0.006) at I104X vs 104I by HLA-Bw4+KIR3DS1+). In longitudinal analysis, higher number of the mutations associated with higher viremia (E93X and I104X) among subjects expressing relevant HLA-KIR combination also had a higher mortality rate (p=0.02) (Figure) and remained significant in multivariate analysis (adjusted HR 1.5 [95%CI 1.1-2.1], p=0.03), independent of sex (2.5 [1.6-3.9], p<0.001 and age (1.0 [0.9-1.0], p=0.3). The number of mutations associated with lower viremia (T122X and M31X) did not have a significant effect on mortality rate (p=0.4). Conclusions: In this study we identified several predominant sites of NK cell-induced immune pressure, and viral adaptation to it, especially with deleterious effects on clinical outcome. These findings will impact the existence of the unique anti-HIV innate immune pressure and viral adaptation to it in each endemic area.

315 Blockade of KIR2DL1/3 Significantly Improves the Anti-HIV-1 Activity of KIR+ NK Cells

Christian Körner 1 ; Camille R. Simoneau 2 ; Mitchell E. Granoff 2 ; Björn Corleis 2 ; Eileen P. Scully 3 ; Douglas S. Kwon 2 ; Stephanie Jost 2 ; Marcus Altfeld 1 1 Heinrich Pette Inst, Hamburg, Germany; 2 Ragon Inst of MGH, MIT, and Harvard, Cambridge, MA, USA; 3 Massachusetts General Hosp, Boston, MA, USA Background: NK-cell function is controlled by inhibitory KIR receptors through their interactions with HLA class I molecules, a process termed “licensing”. However, it remains unclear whether the increased functional competence of licensed NK cells directly translates into increased antiviral activity in HIV-1 infection. We determined the antiviral capacity of KIR2DL1 + and KIR2DL3 + NK cells in the context of the cognate HLA class I ligand HLA-C. Methods: Primary NK cells derived from HIV-1(-) individuals (N=32) were used to quantify the ability of NK cells to inhibit HIV-1 replication in vitro . HIV-1-infected autologous CD4 + T cells were co-cultured with either sorted KIR2DL1 + , KIR2DL3 + or bulk NK cells in the presence or absence of KIR-blocking antibodies for 7 days. Viral RNA was quantified in the supernatant to monitor NK-cell-mediated inhibition of HIV-1 replication. In addition, KIR binding to infected and uninfected CD4 + T cells was assessed using KIR-Fc constructs. Results: NK cells expressing the self-inhibitory receptors KIR2DL1 and KIR2DL3 displayed a reduced ability to inhibit HIV-1 replication as compared to bulk NK cells ( p =0.02). Although infection of CD4 + T cells was associated with significantly reduced KIR binding (p=0.002 for both KIR2DL1-Fc and KIR2DL3-Fc), infected CD4 + T cells displayed residual KIR binding (KIR2DL1 RFI, median: HIV(-):135 vs. HIV(+):28; KIR2DL3 MFI: HIV(-):15 vs. HIV(+):4; n=24). Blockade of self-inhibitory KIRs was associated with improved antiviral capacity ( p <0.0001) while blockade with KIR antibodies not matching donor HLA class I molecules did not affect inhibition of HIV-1 replication ( p =0.8, n=14). Conclusions: Our results show that the ability of NK cells to inhibit HIV-1 replication was limited by expression of self-inhibitory KIR2DL molecules, potentially due to residual KIR binding to infected CD4 + T cells and subsequent inhibition of KIR2DL + NK cells. Blocking of inhibitory KIRs on NK cells unleashed the antiviral activity of these cells. These data provide a rationale for therapeutic blocking of specific inhibitory KIRs in HIV-1 cure approaches, as already investigated in clinical trials in the setting of tumor therapies. 316 IFN-a Augments NK-Mediated ADCC Lysis via VRC01 or HIV-1 Infected Subject Plasma Costin Tomescu 1 ; Brian Ross 1 ; PabloTebas 2 ; Luis J. Montaner 1 1 The Wistar Inst, Philadelphia, PA, USA; 2 Univ of Pennsylvania, Philadelphia, PA, USA Background: Interferon-alpha (IFN-alpha) is a potent clinical immuno-stimulatory agent able to limit viral replication and increase NK activity against HIV-1 infected target cells. We have previously shown that IFN-alpha stimulation augments traditional NK lysis of autologous HIV-1 infected CD4 + primary T cells through the NK activating receptors NKp46 and NKG2D. Here, we investigated if IFN-alpha stimulation could also independently increase NK-mediated Antibody-Dependent Cellular Cytotoxicity (ADCC) of autologous HIV-1 infected CD4 + primary T cells in the presence of antibodies against the HIV-1 viral envelope protein, gp120. Methods: ADCC was triggered with a monoclonal antibody to CD4-binding site of gp120 (VRC01) or plasma from HIV-1 infected subjects (whole or IgG depleted). Autologous CD4 + primary T cells infected in vitro with a panel of lab adapted or primary HIV-1 isolates (IIIB, NL4-3, TYBE) were used as ADCC targets in chromium release assays. In parallel, uninfected CD4 + T cells coated with recombinant gp120 were used as ADCC targets in CD107a degranulation assays. Autologous PBMC (Total or NK-depleted) were used as effectors both ADCC assays in the presence or absence of IFN-alpha pre-stimulation (5000 U/ml). Results: The combination of IFN-alpha pre-stimulation and ADCC antibodies against gp120 including VRC01 or HIV-infected subject plasma significantly increased NK cell- mediated cytotoxicity against autologous HIV-1 infected CD4 + primary T cells ( p<0.05) when compared to either therapy alone. IFN-alpha stimulation also significantly increased ( p<0.01, n=6) CD107a degranulation of NK cells against gp120-coated CD4 + T cells over uncoated background (median=27.5%, Inter-quartile range=8) compared to unstimulated NK cells (median=18.5%, Inter-quartile range=6). Conclusions: In addition to increasing traditional NK cytotoxicity of HIV-infected targets, IFN-alpha also independently augments NK-mediated ADCC lysis of HIV-1 infected autologous CD4 + primary T cells. Our data supports that an increase in ADCC by IFN-alpha can lead to the greater eradication of HIV-1 infected target cells following IFN-alpha immunotherapy alone, or in combination with the anti-gp120 broadly neutralizing monoclonal antibody, VRC01. 317 Immunogenicity and Efficacy of ALVAC-HIV/gp120-Clade C in Alum Regimen in Macaques Luca Schifanella 1 ; DavidVenzon 1 ; Susan Barnett 2 ; Sanjay Phogat 3 ; GeorgiaTomaras 4 ; David Montefiori 4 ; Massimiliano Bissa 1 ;Veronica Galli 1 ; Ruth M. Ruprecht 5 ; Genoveffa Franchini 1 1 NIH, Bethesda, MD, USA; 2 Novartis, Cambridge, MA, USA; 3 Sanofi, Swiftwater, PA, USA; 4 Duke Univ, Durham, NC, USA; 5 Texas Biomed Rsr Inst, San Antonio, TX, USA Background: The RV144, a phase 3 trial held in Thailand, reduced the risk of HIV infection by 31.2%. In our lab we replicated the results of this study in a SIV mac251 models using an ALVAC/SIV-gp120/Alum Alhydrogel vaccine (44% vaccine efficacy). A trial has begun in South Africa (SA) to test a similar vaccine using clade C immunogens. We design a study in which we tested the ALVAC HIV/gp120 Clade C Alum in macaques model Methods: 27 all-female Indian rhesus macaques received at weeks (wk) 0, 4, 12 and 24 intramuscularly 10^8 PFU of both ALVAC vCP172 expressing SIV gag-pol and another and ALVAC vCP1521 expressing ZM96 Clade C HIV gp120 env trans-membrane anchor and the Clade B gag , pro . 200μg of each gp120 (TV1 and 1086) in alum hydroxide (proprietary formulation) were given at weeks 12 and 24. 20 controls received only Alum. 4 wk after last immunization, all the animals were challenged with repeated low doses SHIV1157ipd3N4 via vaginal route 17 times

Poster Abstracts

121

CROI 2016