CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

TUESDAY, FEBRUARY 24, 2015 Session P-F1 Poster Session

Poster Hall

2:30 pm– 4:00 pm Immune-Based Strategies in Latency 368 Stimulation of Broad CTL Response Is Required to Clear Latent HIV-1 in Humanized Mice Liang Shan 1 ; Kai Deng 2 ; Richard Flavell 1 ; Robert F. Siliciano 2 1 Yale University, New Haven, CT, US; 2 Johns Hopkins University School of Medicine, Baltimore, MD, US

Background: Despite antiretroviral therapy (ART), HIV-1 persists in a stable latent reservoir, primarily in resting memory CD4 + T cells.To purge the reservoir, pharmacological reactivation of latent HIV-1 has been proposed and tested both in vitro and in vivo . The next step is to eliminate the resting CD4 + T cells in which latent HIV-1 has been induced through virus-specific immune mechanisms including cytolytic T lymphocytes (CTL). However, the vast majority (>98%) of latent viruses in chronic patients carry CTL escape mutations that render the infected cells insensitive to CTLs directed at common epitopes, such as SL9 epitope in HLA-A2-positive patients. Methods: To test whether CD8 + T cells from patients under ART are able to recognize and clear latent HIV-1, we generated patient-derived humanized mice using a recently reported mouse system named MISTRG. With humanization by knockin replacement of the Csf1 , Csf2, Il3, Tpo and Sirpa genes in the Rag2 -/- Il2rg -/- genetic background, MISTRG mice are highly permissive for human hematopoiesis and support the reconstitution of robust human lymphoid and myelomonocytic systems. We infected patient-derived humanized mice with primary HIV-1 isolates grown from resting CD4 + T cells of the same patient and then evaluated antiviral effect of autologous CD8 + T cells. Results: MISTRG mice engrafted with HLA-A2-positive patient bone marrow CD34 + cells successfully developed human T-lymphocyte and monocyte/macrophage subsets, which were sufficient to support HIV-1 infection. In control mice or mice that received autologous patient CD8 + T cells pre-stimulated with the common epitope SL9, levels of plasma HIV-1 RNA and proviral DNA in PBMCs continued to increase from day 14 to day 29 after infection. In sharp contrast, 100- to 1,000-fold decreases in plasma HIV-1 RNA levels were observed in all mice that received patient CD8 + T cells pre-stimulated with the mixture of Gag peptides including unmutated epitopes.

Poster Abstracts

Broad-spectrum cytotoxic T lymphocytes suppress in vivo infection of patient-derived humanized mice with autologous latent HIV-1 . Conclusions: Our results demonstrate that chronically infected patients retain a broad spectrum viral-specific CTL response which is sufficient to inhibit in vivo replication of HIV-1 isolated from latent reservoir. These results suggest that latent HIV-1 can be eliminated in chronically infected patients despite the overwhelming presence of CTL escape variants. Directing efficient CTL responses to unmutated viral epitopes is essential to the clearance of latent HIV-1. 369 In vivo effects of Panobinostat and Romidepsin on HIV-1-specific CD8 T Cell Immunity Rikke Olesen 1 ;Thomas A. Rasmussen 1 ; Mathias Lichterfeld 2 ; Mette E. Graversen 1 ; Steffen Leth 1 ; Lars Østergaard 1 ; Ole S. Søgaard 1 ; MartinTolstrup 1 1 Aarhus University Hospital, Aarhus, Denmark; 2 Ragon Institute of MIT, MGH and Harvard, Boston, MA, US Background: We recently showed that the histone deacetylase inhibitors (HDACi) panobinostat (PANO) and romidepsin (ROMI) activates HIV-1 from latency in HIV-1 infected patients on antiretroviral therapy (ART). However, concern has been raised that HDACi may diminish effector functions of CD8 T cells, thus impairing the elimination virus- expressing cells. Here, we evaluated HIV-1-specific CD8 T cell responses during clinical administration of PANO and ROMI. Methods: In two separate clinical trials, PANO (20 mg per dose) or ROMI (5mg/m 2 per dose) were administered to virologically suppressed HIV-1 infected adults on ART. In 14 of 15 PANO-treated and 6 of 6 ROMI-treated patients, cryo-preserved PBMCs isolated pre-HDACi (baseline), on-HDACi, and post-HDACi (follow-up) were analyzed by intracellular cytokine staining (ICS) following stimulation with a HIV-1 Gag peptide pool. Cells were labelled with Near-IR amino reactive dye, surface antibodies (CD4, CD8, CD45RA and CCR7) and IFN γ (ICS) and analyzed on a BD FACSVerse cytometer. Comparisons were performed using Wilcoxon matched-pairs test. Results: We observed no overall statistical significant changes in total CD8 T cell counts before and after PANO or ROMI treatment. However, during PANO treatment the relative composition of CD8 T cell subsets changed significantly with increased proportions of effector memory (EM) (p=0.005) and central memory CD8 T cells (p=0.03); and decreased proportions of naïve CD8 T cells (p=0.04). These changes had returned to pre-HDACi levels at follow-up. During ROMI treatment we saw no statistical significant change in the CD8 T cell memory subset composition. The majority of HIV-specific cells in all subjects were EM CD8 T cells. In 11 of 14 (79%) PANO-treated patients and 5 of 6 (83%) ROMI-treated

276

CROI 2015