CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

Methods: To directly evaluate the contribution of the TCR clonotype on the differences observed in effective or ineffective CTL clones, we cloned into TCR-expressing lentivectors the TCR α and β chain genes from one effective and two ineffective CTL clones specific for the same viral peptide, KK10, but with different TCR clonotypes, isolated from an HLA*B2705 elite controller (Chen et al., Nature Immunology 2012;13:691). We used these lentivectors to transduce Jurkat/MA cells, a T cell line engineered to measure TCR signaling using a luciferase reporter, and primary CD8+ T cells to delineate the contribution of the TCR on the functional activity of HIV-specific CTLs. Results: Jurkat/MA cells transduced with lentiviral vectors encoding TCRs cloned from the effective or the two ineffective CTL clones expressed equivalent levels of KK10-specific TCR clonotypes and displayed comparable TCR activation by their cognate peptide, KK10. Primary CD8+ T cells transduced with lentivirus expressing the TCR from the effective CTL clone or the two ineffective CTL clones displayed equivalent levels of the KK10-specific TCR clonotypes and exhibited equivalent potent inhibition (>80%) of in vitro HIV-1 infection. Conclusion: Taken together, these data indicated that TCR clonotypes from ineffective CTLs have the intrinsic capacity to direct primary CD8+ T cells to effectively kill HIV infected cells and support the proposition that other TCR-independent factors such as epigenetic modifications may also contribute to the effective vs. ineffective functions of some CTL clones. The effective control of HIV-1 infection in elite controllers may be due to their capacity to generate and expand these effective clonal CTL populations. 270 HIV-SPECIFIC CD8 T CELLS IN PERSONS TREATED IN FIEBIG I ACUTE INFECTION WHO STOP ART Hiroshi Takata 1 , Donn Colby 2 , Eugene Kroon 2 , Suteeraporn Pinyakorn 1 , Nelson L. Michael 3 , Merlin L. Robb 1 , Jintana Intasan 2 , Jintanat Ananworanich 4 , Lydie Trautmann 1 , for the RV411 and RV254/SEARCH010 Study Groups 1 Walter Reed Army Inst of Rsr, Silver Spring, MD, USA, 2 SEARCH, The Thai Red Cross AIDS Rsr Cntr, Bangkok, Thailand, 3 Walter Reed Army Inst of Rsr, Silver Spring, MD, USA, 4 US Military HIV Rsr Prog, Silver Spring, MD, USA Background: Initiation of antiretroviral therapy (ART) at the earliest stage of acute HIV infection (AHI) partially preserves B cell and mucosal T cell responses. We recently showed that HIV-specific CD8+ T cells generated at Fiebig I were delayed in expanding and acquiring effector functions but were endowed with higher memory potential. Whether these preserved CD8+ T cells play a role in controlling viral rebound following treatment interruption (TI) is unknown. We investigated the HIV-specific CD8+ T cell response after TI in participants who initiated ART during AHI Fiebig I. Methods: Eight HIV infected Thai individuals who initiated ART in during AHI Fiebig I (VL+, p24-, IgM-) were studied longitudinally in AHI and during TI. At the time of TI, all were on ART ≥ 2 years, CD4 T cells ≥ 400 cells/mm 3 and HIV-1 RNA < 50 copies/ml, all rebounded after ART cessation. We analyzed HIV-specific CD8+ T cells defined by the detection of Ki-67 and lack of Bcl-2 longitudinally during AHI and TI by flow cytometry. Results: HIV-specific CD8+ T cells significantly increased at viral rebound compared to baseline prior to TI. Although plasma viral load was significantly lower after TI than at AHI, HIV-specific CD8+ T cell magnitude was higher in TI compared to AHI. Of note, in AHI HIV-specific CD8+ T cells frequencies increased significantly only 10 days after ART initiation. These data suggest that HIV-specific CD8+ T cells expand faster after TI than in AHI. During TI, the frequency of HIV-specific CD8+ T cells and the levels of the transcription factor T-bet (mean fluorescence intensity) were negatively correlated with plasma viremia before ART reinitiation (Fig). Moreover, T-bet expression levels in effector CD8+ T cells in AHI 10 days after ART initiation tended to be associated with T-bet expression at viral rebound in TI (Fig). These data suggest that the frequency of effector HIV-specific CD8+ T cells contributes to limiting viremia after TI and that their differentiation levels in AHI prior to ART imprints their differentiation during TI. Conclusion: Effector CD8+ T cells expand more rapidly after TI than in AHI and contribute to virus control during TI even though they are not sufficient to contain viral rebound. Therefore, pre-TI immune boost strategies to achieve higher quantity and complete effector differentiation of HIV-specific CD8+ T cells may be required for successful viral control after TI in addition to treating early to preserve immune memory.

Poster and Themed Discussion Abstracts

271 EARLY CART OF HIV-1 INFECTED SUBJECTS PRESERVES ANTIVIRAL FUNCTION OF CD8+ T CELLS

Miriam Rosas Umbert 1 , Beatriz Mothe 2 , Gemma Hancock 3 , Hongbing Yang 3 , Christian Manzardo 4 , Josep Coll 1 , Christian Brander 1 , Lucy Dorrell 3 1 IrsiCaixa AIDS Rsr Inst, Badalona, Spain, 2 Hosp Germans Trias i Pujol, Badalona, Spain, 3 Univ of Oxford, Oxford, UK, 4 Univ of Barcelona, Barcelona, Spain

Background: Recent data from several clinical trials highlight the benefits of early antiretroviral treatment, including a better CD4 cell recovery, normalization of CD4/CD8 ratios, smaller HIV reservoir and limited viral diversification. Since such clinical benefits may be mediated, at least in part, by a robust and functionally intact antiviral CD8 T cell response, we assessed the HIV suppressive capacity of CD8 T cells ex vivo in replication inhibition assays in a cohort of early treated individuals. We compared these data with individuals treated at chronic stages of HIV infection. Methods: 24 early-treated individuals (<6m from HIV-1 acquisition, median time of 84 days (Early cART) who initiated TDF/FTC/RAL 1 week after diagnosis were recruited at two HIV outpatient clinics in Barcelona. We measured CD8+ T-cell mediated viral inhibitory capacity against HIV-1 BaL and IIIB isolates at different CD8:CD4 ratios (E:T = 1:1, 1:2 and 1:10) in longitudinal cryopreserved samples obtained at 6 and ~1 year (13 -15 months) after treatment initiation. Changes in activation markers (HLA-DR, CD38, CD69, CD25) on total CD4 and CD8 were assessed by flow cytometry. Total HIV-specific T cell responses were assessed by IFNg ELISPOT. Viral inhibition data from 19 individuals who started treatment in chronic infection and had been virologically suppressed for at least one year (Chronic cART) was used for comparison. Results: At one year after treatment initiation, CD8+ T cell viral inhibition was significantly higher in early treated individuals (median 68%) chronic cART individuals (median 20%, p=0.0001). This higher suppressive

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