CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Results: Most HIV replication variability in MDM was accounted for by viral strain (75.3%, p<0.001), although a significant, but smaller, proportion of variability was attributed to the donor (9.49%, p<0.001; n=5). Among the 13 viral strains, 11 significantly reduced MDM HO-1, but not HO-2, protein expression (p<0.05). This reduced HO-1 protein expression correlated significantly with increased viral replication, supernatant neurotoxicity, and extracellular glutamate (p<0.001). The viral inoculum of a single viral strain (89.6) predictably correlated positively with viral replication and supernatant neurotoxicity and negatively with HO-1 protein expression. Despite altered replication kinetics, infection of MDM with mutant 89.6 HIV molecular clones lacking Nef, Vpr, or Vpu, nonetheless reduced HO-1 protein expression (p<0.05). Chronic exposure (9 days) to the cytokines TNF α , IL-1 β , IL-18, IL-23, and GM-CSF also reduced HO-1 protein expression in uninfected MDM (p<0.05). Conclusions: Infection with most, if not all, macrophage-tropic HIV-1 strains reduce HO-1 protein expression in human macrophages. This reduction of HO-1 protein expression correlates with viral replication and likely augments HIV-MDM neurotoxin production. The HIV accessory proteins Nef, Vpr, and Vpu are not required for HIV-mediated HO-1 deficiency in macrophages. However, chronic inflammatory signaling associated with HIV replication may play a role in HIV-mediated reduction of HO-1. 502 Atorvastatin Reverses the HIV-induced HO-1 Defect in Primary Human Macrophages Melanie R. Duncan ; Alexander J. Gill; AnjanaYadav; Dennis L. Kolson; Ronald G. Collman University of Pennsylvania, Philadelphia, PA, US Background: HIV-associated neurocognitive disorders (HAND) are a collection of neurological deficits characterized by cognitive, motor, and behavior abnormalities, and remains a significant problem in ART-treated infected individuals. Neurological injury in HAND is a consequence of both persistent immune activation and the release of neurotoxins, such as glutamate, by HIV-infected and/or activated macrophages and microglia. Previous studies have implicated several macrophage enzymes in these neurodegenerative processes, including the cytoprotective enzyme heme oxygenase-1 (HO-1), glutaminase isoforms, and indoleamine 2,3-dioxygenase (IDO), that are disturbed by HIV infection. Statins (HMG-CoA reductase inhibitors) have pleiotropic immunomodulatory effects independent from their cholesterol-lowering abilities, such as downregulating monocyte/ macrophage activation and inflammation. Therefore, we hypothesized that statins would modulate the levels of proteins associated with inflammation and neurological injury in HIV-1 infected macrophages. Methods: Primary monocyte-derived macrophages (MDM) were infected in vitro with the macrophage-tropic HIV-1 strain YU-2. After 4-8 days, following establishment of infection (verified by supernatant p24 Gag antigen), cells were treated with atorvastatin (10 μ M). After 6-48 hours, cells were lysed and protein expression of HO-1, IDO, and glutaminase isoforms were assessed by Western blot analysis. Results: HIV-1 infection of MDM reduced HO-1 and increased IDO protein expression, as previously reported. We found that treatment with atorvastatin for 12-24 hours on day 8 post-infection increased HO-1 protein expression, partially reversing the HIV-mediated reduction. Similarly, treatment with atorvastatin for 6 hours on day 4 post-infection increased the level of HO-1. In contrast, atorvastatin had no effect on two isoforms of glutaminase, KGA and GAC. Effects on IDO were modest and inconsistent. Conclusions: Atorvastatin partially reverses the HIV-mediated reduction of HO-1 in macrophages. Brain and macrophage HO-1 deficiency in HIV-infection has been implicated in HAND pathogenesis. Thus, statin drugs through HO-1 induction could be useful as an adjunctive therapy for HAND in HIV-infected ART-treated individuals. 503 Enhanced Antagonism of BST-2 by Neurovirulent SIV Envelope Kenta Matsuda ; Chia-Yen Chen; FanWu; Ronald Plishka; Alicia Buckler-White; Klaus Strebel;Vanessa M. Hirsch National Institutes of Health (NIH), Bethesda, MD, US Background: Although neuroAIDS or AIDS dementia caused by HIV-1 has been declining in clinical practice due to the use of Highly Active Antiretroviral Therapy (HAART), a milder neurologic disorder termed Minor Cognitive Motor Disorder (MCMD) continues to be a significant clinical problem. To develop new strategies to intervene in HIV disease progression in the brain, our lab has been developing a novel nonhuman primate neuroAIDS model by in vivo passage of SIVsmE543-3, a strain that is capable of inducing AIDS in the infected rhesus macaques but not SIV encephalitis (SIVE). As a result, we have recently isolated a viral strain, SIVsm804E, which can cause neuroAIDS in infected animals at high frequencies (Matsuda et al., JVI 2013, Matsuda et al., JVI 2014). A molecular clone, SIVsm804E CL757 was then isolated from the SIVsm804E viral swarm. Introduction of the gp41 cytoplasmic tail of Env of this molecular clone into the parental SIVsmE543-3 backbone, resulted in improvement of viral replication in monocyte derived macrophages (MDMs) in vitro. It has been previously reported that the cytoplasmic tail of gp41 of SIV plays an important role in the antagonism of the host factor, bone marrow stromal antigen 2 (BST-2, also known as Tetherin), that impairs the release of nascent viral particles from the virus-producing cells (Serra-Moreno et al., Cell host microbes 2011). Methods: To determine whether efficient antagonism of BST-2 is responsible for the improvement of replication in macrophages, pulse-chase and immmunoprecipitation assays were conducted to compare the efficacy of BST-2 antagonism by the original SIVsmE543 to that of a variant with the cytoplasmic tail mutations found in SIVsm804E CL757. Results: Preliminary data show that multiple mutations in the cytoplasmic tail of gp41 individually enhance viral release from the cells expressing BST-2. Since macrophages are the main target for viral infection and replication in the brain of SIV infected animals, our results suggest that our virus acquired mutations in the cytoplasmic tail of gp41 for efficient replication in the central nervous system (CNS). Conclusions: Although SIV and HIV-1 utilize different viral proteins to antagonize BST-2, our data suggest that BST-2 may play an important role in the suppression of viral replication in the CNS and intervention of viral factors that antagonize BST-2 could be a novel strategy for prevention of disease progression in the CNS during HAART. 504 MEMRI Reflects HIV-1-Associated Human Pathobiology in a Rodent NeuroAIDS Model Aditya N. Bade ; Santhi Gorantla; Prasanta K. Dash; Edward Makarov; Balasrinivasa R. Sajja; Larisa Poluektova; Howard Gendelman; Michael Boska;Yutong Liu University of Nebraska Medical Center, Omaha, NE, US Background: Progressive human immunodeficiency viral (HIV) infection commonly leads to a constellation of cognitive, motor and behavioral impairments. While antiretroviral therapy (ART) reduces disease severity, it does not affect disease prevalence. There are no diagnostic biomarkers for neuroAIDS and co-morbid conditions must first be excluded. To this end, we applied manganese (Mn 2+ )-enhanced magnetic resonance imaging (MEMRI) to noninvasively assess virus-induced neuropathology in a human disease relevant rodent neuroAIDS model. Methods: Humanized mice (NOD/scid-IL-2R γ c null ) reconstituted at birth with human CD34+ hematopoietic stem cells were infected with HIV-1 ADA (i.p. at 10 4 TCID 50 ) at 22 weeks of age. Infection was followed for 16 weeks. Uninfected humanized mice used as controls. Flow cytometry for peripheral blood leukocytes was performed at 2, 4, 7, 10, 13 and 16 weeks post infection (WPI) to determine proportions of peripheral human immune cells. Plasma viral RNA copies/ml (viral load, VL) measures were performed at 2, 7, 16 WPI. Animals were MEMRI tested at 16 wpi to measure signal enhancement and morphological changes. Furthermore, an MEMRI-based brain atlas, the T 1 -wt signal enhancement on 41-brain regions/sub-regions was calculated and student’s t-test performed to examine enhancement significance. Immunohistochemistry was performed at study termination. Brain sections were stained for human cells, virus infected human cells, neuronal, oligodendrocytes and glial inflammatory markers. Results: CD4+ T cell decline and concomitant increases in CD8+ T cells were seen in the HIV-1 infected mice. Control uninfected animals showed no changes in cell numbers. VL values peaked at the 2 nd week after HIV-1 infection and were sustained throughout the study. Human (HLA-DR+) cells infiltrated the brains of infected and control mice were

Poster Abstracts

333

CROI 2015