CROI 2017 Abstract e-Book

Abstract eBook

Oral Abstracts

spinoculation. Lymph node cells (LN) from HIV+ untreated subjects were sorted into EF, EF Treg, TFH and TFR, and RNA quantified by RT PCR. Data were log transformed. Mixed- effects models and repeated-measures ANOVA were used with pairwise tests if overall p<0.05. Geometric means and 95% CIs are reported. Results: GFP expression differed by cell type (p≤0.001) with %GFP+ cells in TFR (2.0%; 1.3, 2.8) > EF Treg (0.6%; 0.4, 0.9), TFH (0.3%; 0.2, 0.5) > EF (0.09%; 0.04, 0.18), and TFR > TFH (n=6; p<0.01). The same pattern was observed for p24 Ag expression in T/F infections (n=6; overall p<0.01). %Ki67 expression differences between cell subsets at day 0 (n=6; p<0.001) paralleled differences in %GFP and %p24 expression, but CCR5, CD95, and CD69 expression did not. At day 0 for each 1 log10 increase in %Ki67 expression, there was a 0.8 (0.6, 1.1) log10 increase in %GFP expression (p<0.001). Compared to untreated cells, imatinib reduced Ki67 expression by 34% (6, 53; p=0.02) and reduced GFP expression by 77% (61, 87; p<0. 001), without affecting viability. In sorted HIV+ LN, TFR harbored more (1167; 207, 6577) HIV RNA copies/ng total RNA than TFH (585; 113, 3020), EF Treg (516; 163, 1641), and EF (71; 10, 507) (n=6; overall p=0.04; pairwise p<0.05). LN Ki67 expression was higher in TFR (20%; 13, 30) than TFH (10%; 7, 15) and higher in EF Treg (19%; 15, 24) than EF (4.7%; 2, 10) (n=6; overall p=0.01; pairwise p<0.05). Conclusion: TFR are highly permissive to HIV, likely due to heightened proliferation, and harbor the highest concentrations of HIV RNA in vivo . 64LB VIRION INCORPORATION OF INTEGRIN α4β7: IMPLICATIONS FOR HIV-1 PATHOGENESIS Christina Guzzo , David Ichikawa, Chung Park, Cathy Rehm, Claudia Cicala, James Arthos, Anthony S. Fauci, John Kehrl, Paolo Lusso NIAID, Bethesda, MD, USA Background: The intestinal mucosa is a key anatomical site for HIV-1 replication and CD4+ T-cell depletion. Accordingly, a series of in vivo studies in macaques showed that antibody-mediated blockade of the principal gut-homing integrin, α4β77, resulted in reduced SIV transmission, delayed disease progression, and effective virus control persisting for months after antibody withdrawal. We aimed at elucidating the potential mechanism(s) underlying the protective effects of anti-α4β77 antibody treatment. Methods: HIV-1 strains were grown in human PBMC activated in the presence/absence of retinoic acid; virion-capture assays were performed using magnetic beads armed with antibodies to α44β77 or other cellular receptors, or recombinant MAdCAM-1 or ICAM-1; α44β77+ or – viral particles were produced by co-transfection of 293T cells with HIV-1 clones with or without α44 and β77; for virion-homing studies, fluorescent α44β77+ or – virus was injected into the tail vein of C57BL/6 mice, and tissues were harvested after 30 min. Results: We found that integrin α44β77 is incorporated with remarkably high efficiency into the envelope of mature HIV-1 particles. Virion-incorporated α4β7 is functionally active as it binds the specific integrin ligand, MAdCAM-1, promoting HIV-1 capture by and infection of MAdCAM-expressing cells, which in turn mediates trans-infection of bystander susceptible cells. In vivo homing experiments in mice documented a selective and specific uptake of α4β7+, but not α4β7- HIV-1 virions by high endothelial venules in the Peyer’s patches of the intestinal mucosa. The physiological relevance of α44β77 incorporation was corroborated by the observation that circulating virions from both HIV- infected patients and SIV-infected macaques invariably carry functional α44β77 in their envelope, with peak incorporation levels occurring during the early stages of infection, when the intestinal mucosa is still richly populated with α44β7-7high CD4+ T cells. Conclusion: Our results provide new insights to interpret the protective effects of anti-α44β77 antibody treatment and may be relevant for the pathogenesis, therapy and prevention of HIV-1 infection. 65 DEFINING THE NATURE OF CD8+ T-CELL RESPONSES IN LYMPH NODES OF HIV ELITE CONTROLLER Son Nguyen 1 , Marcus Buggert 1 , Ali Naji 2 , Perla Del Río-Estrada 3 , Gustavo Reyes-Terán 3 , Steven G. Deeks 4 , Michael R. Betts 1 1 Univ of Pennsylvania, Philadelphia, PA, USA, 2 Hosp of the Univ of Pennsylvania, Philadelphia, PA, USA, 3 Rsr Cntr in Infectious Diseases, Mexico City, Mexico, 4 Univ of California San Francisco, San Francisco, CA, USA Background: CD8+ T cells are strongly linked to viral control mechanisms in HIV elite controllers. Substantial evidence has suggested that cytolytic activity and other effector functions are the mechanism by which these cells control HIV, at least in blood. However, the vast majority of HIV replication in elite controllers likely occurs in lymphoid tissue, where CD8+ T cell immune surveillance mechanisms are undefined. Here we directly assessed the functional and phenotypic properties of tissue-based HIV-specific CD8+ T cells in the lymphoid tissues controllers. Methods: We obtained human peripheral blood mononuclear cells (PBMC) and lymph node mononuclear cells (LNMC) from HIV-infected controllers, non-controllers and ART-treated individuals. We performed multi-parametric flow cytometry to define the phenotypic and functional profile of HIV-specific CD8+ T cells as identified by MHC-class I tetramers or responsiveness to peptide stimulation. The results were analyzed using FlowJo, GraphPad Prism, and SPICE. Results: We here demonstrate that cytolytic memory CD8+ T cells, as defined by the expression of perforin and granzyme B, are almost absent in lymph nodes (LN) of elite controllers. While high frequencies of HIV-specific CD8+ T cells could readily be detected in LN by MHC-class I tetramers, these cells very rarely express perforin and granzyme B. Instead, HIV-specific CD8+ T cells from LN of controllers possess high levels of non-cytolytic polyfunctional responses directed against HIV peptides. Such responses were low or absent in non-controllers or those on ART. HLA-B27/57+ elite controllers demonstrate a selective and high frequencies of CD8+ T cells targeting immunodominant Gag epitopes. Finally, HIV-specific LN CD8+ T cells from EC do not display enhanced ability to enter B cell follicles as defined by the expression of the chemokine receptor CXCR5, nor are those CXCR5+ cells more cytolytic compared to non-controllers and those on ART. Conclusion: Together these findings redefine previous concepts of CD8+ T cell mediated control of HIV disease progression. During established infection, HIV replication appears to be controlled in lymphoid tissues by non-cytolytic rather than cytolytic mechanisms. Knowledge regarding how HIV is controlled in this setting should be used to inform the identification and development of potentially curative interventions.

Oral Abstracts

66 HIV-SPECIFIC BINDING ANTIBODY PROFILES ASSOCIATED WITH BROADLY NEUTRALIZING ACTIVITY Claus Kadelka , Thomas Liechti, Hanna Ebner, Peter Rusert, Roger Kouyos, Huldrych F. Günthard, Alexandra Trkola Univ of Zurich, Zurich, Switzerland Background: Potent broadly neutralizing antibodies (bnAbs) are a key focus of vaccine and therapy development but they are only elicited at low frequency in natural infection. Understanding and overcoming these restrictions in bnAb induction will be decisive for HIV vaccine design. To define factors that govern bnAb induction we recently conducted the Swiss 4.5K Screen, a systematic survey of bnAb activity in 4,484 HIV-1 infected individuals (Rusert, Kouyos Nat Med 2016). This led to the identification of 239 bnAb inducers as well as the definition of several viral and disease parameters associated with bnAb development. Here, we report on an in-depth analysis of HIV-1 binding antibody data to define if and which binding antibody responses predict bnAb activity. Methods: 4,391 plasma samples previously analyzed within the Swiss 4.5K Screen for neutralization activity were probed for binding antibodies of IgG subclasses 1, 2 and 3 against 13 HIV-1 proteins and peptides encompassing Gag (p17, p24) and Env (see Figure) using an in-house established Luminex bead assay. The area under the ROC-curve (AUC) was used to measure predictive power. Results: Plasma samples with bnAb activity exhibited a generally higher Env binding reactivity. IgG1 binding activities to the gp140 BG505 trimer (AUC=0.85), followed by IgG2 trimer binding (AUC=0.76) and IgG2 binding to gp120 JR-FL (AUC=0.72) were particularly good predictors of HIV-1 neutralization breadth (see Figure). While

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CROI 2017