CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

Methods: The ecto- and transmembrane domains of the vesicular stomatitis virus (VSV)-G gene were replaced with those of HIV-1 Env to make RhIV. Transgenic mice were generated using a construct encoding human CD4 and CCR5 downstream of mouse CD4 transcriptional control elements. Mice deficient in type I IFN receptor signaling were made by backcrossing into IFNAR1-null mice. Results: IFN competent (gray) or null (black) mice expressing hCD4,CCR5 were infected with RhIV.BG505 (red arrows). All animals showed significant CD4 cell depletion in as little as 4 days post infection (A), with the IFNAR1 -/- animals exhibiting an almost complete loss. Viral RNA in plasma peaked in all animals at 1 dpi (B), then rapidly declined. At 14 dpi, BG505.SOSIP-binding antibodies were readily detected by ELISA (C, upper panel). The titers of these antibodies increased significantly following a second infection (C, lower panel). The extent of CD4 depletion and level of plasma viremia were dramatically reduced following each subsequent infection (A&B, red arrows). Conclusion: We have developed a model system in which the efficacy of HIV-1 prevention strategies that focus on blocking envelope/receptor interactions can be quickly assessed in a sensitive, in vivo setting. Additionally, the combination of RhIV with our hCD4/CCR5 mouse model enables the antibody responses to many different HIV-1 envelopes to be rapidly tested. This unique system enables us to investigate envelope immunogenicity in the context of a replication competent RNA virus, including the possibility of evolving interactions between HIV-1 envelope and anti-envelope antibodies.

Poster and Themed Discussion Abstracts 221 RAPID T FOLLICULAR HELPER CELL RECONSTITUTION IN LYMPH NODES AFTER ART INITIATION Chun-Shu Wong 1 , Afroditi Boulougoura 1 , Angela Kibiy 2 , Jeremy Davis 3 , Stefania Pittaluga 3 , Maura Manion 1 , Andrea Lisco 1 , Virginia Sheikh 4 , JoAnn Mican 1 , Irini Sereti 1 1 NIAID, Bethesda, MD, USA, 2 Leidos Biomed Rsr, Bethesda, MD, USA, 3 NCI, Bethesda, MD, USA, 4 FDA, Silver Spring, MD, USA Background: T follicular helper cells (Tfh), defined as CD3+CD4+PD-1+CXCR5+, are specialized T cells, residing in the B cell follicles that assist in B cell survival, proliferation, antibody class switching, and differentiation. The loss of Tfh cells, in chronically infected individuals, is associated with immune dysfunction. Tfh cells have also been implicated as a persistent reservoir of virus-infected cells in persons treated with antiretrovirals (ART) with undetectable plasma HIV RNA levels. Herein, we studied the dynamics of Tfh cells in lymph nodes (LN) before and shortly after ART initiation. Methods: ART-naïve patients with CD4 counts <100cells/µL were enrolled in a prospective study, Inguinal LNs were collected at baseline (pre-ART) and 4-8 weeks post-ART and cells were extracted for immunophenotyping for flow cytometry. Mann-Whitney test and Wilcoxon matched pair test was used to compare groups, while Spearman’s rank correction coefficient was used to test associations. Results: 22 patients, with a median age of 36 (22-53), 6 females and 16 males, were included and underwent LN biopsies including 13 with paired (pre/post-ART) sampling. Median CD4 count at baseline was 23 cells/µL, and median HIV-RNA was 136,677 cp/mL. Median CD4 count after ART was 82 cells/µL, while median HIV-RNA was 78 c/mL (Table). In addition, median CD8 T cells counts in peripheral blood also increased post-ART from 527 to 713 cells/µL. Subsets of CD4 T cells (naïve, effector, central memory and Treg) did not differ significantly post-ART in LN. The CD8 percentage in LN decreased significantly (X vs y, P) post-ART. The percent of CD4 T cells in LN increased post-ART although the difference was only significant in paired analysis of the 13 paired sample subgroup (X vs Y, P). In contrast, the percentage of Tfh cells increased post-ART treatment in both paired and unpaired analysis (Figure). This increase of Tfh cells was not associated with baseline or post-ART HIV-RNA or CD4 count recovery. Conclusion: Tfh emergence in lymph nodes of advanced patients initiating ART occurs early after ART initiation and is independent of plasma viremia or CD4 restoration. The mechanisms of this accumulation are unclear and may have implications in their functionality and their role as HIV reservoirs. 222 INFLAMMASOME AND PYROPTOSIS ARE INVOLVED IN THE LACK OF IMMUNE RESPONSE DURING CART Michela Masetti 1 , Massimiliano Fabbiani 2 , Mara Biasin 1 , Antonio Muscatello 2 , Nicola Squillace 2 , Elisa Colella 2 , Mario Clerici 3 , Andrea Gori 2 , Daria Trabattoni 1 , Alessandra Bandera 2 1 Univ of Milan, Milan, Italy, 2 San Gerardo Hosp, Monza, Italy, 3 Univ of Milan, Segrate, Milan, Italy Background: Inflammasome-mediated activation of caspase-1 regulates inflammatory responses and pyroptosis. Pyroptosis was recently shown to play a major role in CD4 T lymphocyte loss and to contribute to immune activation in HIV infection1.The possible role of inflammasomes and pyroptosis in the lack of immune reconstitution seen in a percentage of ART-treated HIV patients has nevertheless not been investigated. We analyzed possible associations between inflammasome activity, caspase-1 activation, pyroptosis and immune reconstitution in HIV+ ART treated patients1Doitsh G et al., 2014

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CROI 2017