CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: The main determinant for macrophage tropism is the HIV-1 envelope. Our findings demonstrate that recombinant viruses containing envelopes isolated at rebound after ATI are able to fuse and spread infection to macrophages. Phylogenetic relationships indicate that from the beginning of rebound to sampling there was not enough time for macrophage tropic variants to evolve from T-tropic ones, suggesting that M-tropic variants may constitute part of an independent HIV-1 reservoir. Thomas D. Zaikos , Valeri Terry, Nadia T. Sebastian Kettinger, Andrew J. Neevel, Ryan Yucha, Kathleen L. Collins University of Michigan, Ann Arbor, MI, USA Background: Long-lived reservoirs of HIV are a major barrier to cure. Resting memory CD4+ T cells are the best-characterized and largest reservoir of persistent HIV. However, non-T cell reservoirs have also been described. Hematopoietic stem and progenitor cells (HSPCs) have the capacity for life-long survival, self-renewal, and are susceptible to HIV infection. Here, we investigate the contribution of HIV-infected HSPCs to the persistent viral reservoir in 43 optimally-treated, HIV-infected people. Methods: Nucleic acid was isolated from peripheral blood mononuclear cells (PBMCs), bone marrow-derived HSPCs, HSPC-depleted bone marrow mononuclear cells (BMMCs), and residual plasma virus (rPV) from treated HIV-infected people with undetectable viral loads (<50 copies/mL) for at least 6 months. Single-genome PCR products were directly sequenced to compare the genetic relatedness of HIV from each tissue source. Results: We obtained HIV sequences from HSPCs of 25 donors and amplified rPV from all but one. Interestingly, proviruses in HSPCs from 8 donors were identical to rPV across the amplified regions. One donor harbored a provirus lacking the primer binding site within the 5’ LTR. This signature deletion was recovered from HSPCs, BMMCs, PBMCs, and rPV (Fig. a). As this defect is predicted to render HIV non-infectious but capable of viral outgrowth, these data support the conclusion that HSPCs can harbor and propagate HIV genomes to other cell types by cellular proliferation and differentiation. Consistent with this, HSPC-derived proviral genomes were more likely than PBMC-derived sequences to exactly match other proviral genomes (27% vs. 9%; Fig. b). In addition, HSPC-derived sequences were 3-fold more likely to be identical to rPV amplicons than those isolated from PBMCs (Fig. b). Remarkably, we also evaluated 18 HSPC-derived near full-length HIV proviral sequences, of which 5 (28%) contained intact open reading frames and cis elements (Fig. c), a much higher proportion than the ~2-5% published for T cells. Moreover, of these 5 intact, near full-length genomes, 3 (60%) were identical to rPV sub-genomic amplicons (Fig. c). Conclusion: These results provide evidence that HIV-infected HSPCs form a small, but functionally significant reservoir of persistent HIV in infected people. Compared to sequences from other cellular sources, HSPC-associated HIV proviral genomes were more frequently intact and more frequently matched rPV, indicating that they form a unique population with distinct characteristics.

375 SIV PROVIRAL LANDSCAPE DIFFERS FROM THAT OF HIV-1 AND SHOWS GROSS HYPERMUTATION Alexandra J. Murray 1 , Katherine Bruner 1 , Mithra R. Kumar 1 , Andrew Timmons 1 , Po-Ting Liu 2 , Janice E. Clements 1 , Dan Barouch 2 , Janet Siliciano 1 , Robert Siliciano 1 1 Johns Hopkins Hospital, Baltimore, MD, USA, 2 Beth Israel Deaconess Medical Center, Boston, MA, USA Background: HIV-1 establishes latency in a small pool of resting memory CD4+ T cells that represent the major barrier to cure. Various cure strategies are being tested in SIV-infected rhesus macaques as a model for HIV-1 infection. While the proviral genomic landscape has been characterized in HIV-1-infected patients, little is known about the proviruses persisting in SIV-infected macaques. Methods: We developed an unbiased, single-genome-amplification method to capture both intact and defective proviral genomes from CD4+ T cells isolated from 7 long-term chronically SIV-infected ART-suppressed rhesus macaques. PCR primers were designed to amplify near-full-length proviral genomes. PCRs were set up at a limiting dilution, with one or fewer proviruses per well. Reactions were visualized on agarose gels and resulting bands were directly sequenced using either Sanger or Illumina platforms. Results: At least 75% of proviruses were defective. Strikingly, over half of these proviruses showed gross hypermutation, including a subset that also contained internal deletions. Proviruses containing small, internal deletions at the 3’ end of the genome were also frequently detected. These deletions ranged in size and affected the env, tat, rev, and nef genes, while a distinct subset contained much larger deletions (>6 kb), encompassing most of the genome. In contrast to what was seen in CD4+ T cells isolated from HIV-1-infected patients on ART, a significantly larger proportion of proviruses had intact genomes. These findings differ from the proviral landscape of HIV-1-infected individuals who began ART during chronic infection, in whom 80% of proviruses had internal deletions, 7% strikingly different than that in HIV-1-infected CD4+ T cells. A marked majority of SIV proviruses were grossly hypermutated. The pattern of hypermutation differs from HIV-1 proviruses in its severity, both across and within proviral genomes. Additionally, far more intact proviruses were detected in SIV-infected, ART-suppressed macaques than in HIV-infected, ART-suppressed patients. Other populations of SIV-infected monkeys will need to be studied, as these major differences between the HIV-1 and SIV pools of latent proviruses have implications for NHP models of HIV latency and treatment. 376 IL-10 SIGNALING IS A KEY MECHANISM OF SIV PERSISTENCE IN ART- TREATED RHESUS MACAQUES Justin L. Harper 1 , Maria Pino 1 , Luca Micci 1 , Susan P. Ribeiro 2 , Claire Deleage 3 , Hong Wang 1 , Colin T. King 1 , Daniel Gorman 4 , Jacob D. Estes 3 , Rafick-Pierre Sekaly 2 , Mirko Paiardini 1 1 Yerkes National Primate Research Center, Atlanta, GA, USA, 2 Case Western Reserve University, Cleveland, OH, USA, 3 Leidos Biomedical Research, Inc, Frederick, MD, USA, 4 Merck & Co, Inc, Palo Alto, CA, USA Background: The mechanisms regulating the establishment/maintenance of HIV reservoirs are still to be determined, thus impeding the design of strategies limiting HIV persistence. Interleukin (IL)-10 is a key component of the host anti-inflammatory activities triggered by pathogen induced pro-inflammatory responses. IL-10 signaling inhibits the production of Th1 cytokines and stimulates the production of Th2 cytokines; upregulates the expression of co-inhibitory receptors such as PD-1 and CTLA-4; reduces antigen presentation and increases T cell anergy. As a result of these anti-inflammatory activities, we hypothesized that IL-10 can negatively impact on T cell function, lead to a status of immunosenescence, and favor HIV persistence. Methods: 15 RMs were infected with SIVmac239 and started on ART (tenofovir, emtricitabine, raltegravir, darunavir, and ritonavir) at day 58 post-infection (p.i.). ART was maintained for 7 months. Blood (PB), lymph node (LN), and rectal biopsy (RB) were collected longitudinally for flow cytometric and DNAscope analyses. Cell-associated SIV DNA was quantified in CD4 T cell subsets, including Tfh. Results: Plasma and LN levels of IL-10 increased upon SIV infection (p=0.0001 as compared to pre infection) and did not fully normalize with ART. Plasma IL-10 at pre-ART correlate with markers of disease progression such as plasma viremia (p=0.0016); the depletion of CD4 T cells in PB (p=0.0003) and RB (p=0.0422); and plasma IP-10 (p=0.0001). Additionally, plasma IL-10 at pre-ART correlates were hypermutated, and 8% had both hypermutations and deletions. Conclusion: The proviral landscape in these SIV-infected macaques is

374LB HEMATOPOIETIC STEM AND PROGENITOR CELLS ARE A UNIQUE FUNCTIONAL HIV RESERVOIR

Poster Abstracts

CROI 2018 131