Macrophage Tropism of Human Immunodeficiency Virus Type 1 Isolates from Brain and Lymphoid Tissues Predicts Neurotropism Independent of Coreceptor Specificity

Abstract

The viral determinants that underlie human immunodeficiency virus type 1 (HIV-1) neurotropism are unknown, due in part to limited studies on viruses isolated from brain. Previous studies suggest that brainderived viruses are macrophage tropic (M-tropic) and principally use CCR5 for virus entry. To better understand HIV-1 neurotropism, we isolated primary viruses from autopsy brain, cerebral spinal fluid, blood, spleen, and lymph node samples from AIDS patients with dementia and HIV-1 encephalitis. Isolates were characterized to determine coreceptor usage and replication capacity in peripheral blood mononuclear cells (PBMC), monocyte-derived macrophages (MDM), and microglia. Env V1/V2 and V3 heteroduplex tracking assay and sequence analyses were performed to characterize distinct variants in viral quasispecies. Viruses isolated from brain, which consisted of variants that were distinct from those in lymphoid tissues, used CCR5 (R5), CXCR4 (X4), or both coreceptors (R5X4). Minor usage of CCR2b, CCR3, CCR8, and Apj was also observed. Primary brain and lymphoid isolates that replicated to high levels in MDM showed a similar capacity to replicate in microglia. Six of 11 R5 isolates that replicated efficiently in PBMC could not replicate in MDM or microglia due to a block in virus entry. CD4 overexpression in microglia transduced with retroviral vectors had no effect on the restricted replication of these virus strains. Furthermore, infection of transfected cells expressing different amounts of CD4 or CCR5 with M-tropic and non-M-tropic R5 isolates revealed a similar dependence on CD4 and CCR5 levels for entry, suggesting that the entry block was not due to low levels of either receptor. Studies using TAK-779 and AMD3100 showed that two highly M-tropic isolates entered microglia primarily via CXCR4. These results suggest that HIV-1 tropism for macrophages and microglia is restricted at the entry level by a mechanism independent of coreceptor specificity. These findings provide evidence that M-tropism rather than CCR5 usage predicts HIV-1 neurotropism.

Cerebrospinal Fluid HIV Escape from Antiretroviral Therapy

“…As systemic infection progresses, CSF viruses may show more diverse compartmentalization involving R5 viruses that infect macrophages and related cells (referred to as M-tropic) [24][25][26][27][28][29]. While full formal proof of this remains to be shown, it is likely that these viruses are important in the development of encephalitis, in which productive infection can be identified in perivascular and parenchymal macrophages and microglial cells [30].…”

Contribution of Proteoglycans to Human Immunodeficiency Virus Type 1 Brain Invasion

“…We generated a panel of pNL4.3-derived infectious molecular clones in which the envelope gene had been replaced with those encoded by a selection of isolates, including wild-type pNL4.3 (generously contributed by Malcolm Martin through the AIDS Research and Reference Reagent Program) (1), the gp120-deficient virus pNL4.3-E-(generously contributed by Nathaniel Landau through the AIDS Research and Reference Reagent Program) (19,36), pNL-ADA, pNL-JRFL, pNL-YU2, pNL91US005.11, pNL-92MW965.26, pNL-RW020.5, and pNL-92BR020.4 as R5 viruses, pNL-HXB, pNL-92UG021.6, pNL-92UG024.2, and pNL-92HT599.24 as X4 viruses, and finally, pNL-89.6 as R5X4 virus (a generous gift from P. Bieniasz) (97). The primary viruses isolated from matched brain and lymphoid tissues were derived and amplified as described previously (32).…”

“…The following three pairs of viruses isolated from the brain (br) and either the spleen (spln) or lymph nodes (LN) were tested for transmigration by using the assay described above: MACS1-br and MACS1-spln, MACS2-br and MACS2-LN, and MACS3-br and MACS3-LN (32). MACS1-br and MACS1-spln are R5X4 viruses, whereas MACS2-br, MACS2-LN, MACS3-br, and MACS3-LN are R5 viruses (32). The brain-derived viruses did not cross the BMEC monolayer more efficiently than lym- (Fig.…”

“…To address this issue, we compared the transmigration capacities of pairs of primary viruses isolated from the same AIDS patients with dementia, either from the brain (frontal lobe) or from lymphoid tissues (spleen or lymph node) on April 8, 2019 by guest http://jvi.asm.org/ (32). Isolated viruses were amplified in CD8-depleted peripheral blood mononuclear cells as described previously (32). The following three pairs of viruses isolated from the brain (br) and either the spleen (spln) or lymph nodes (LN) were tested for transmigration by using the assay described above: MACS1-br and MACS1-spln, MACS2-br and MACS2-LN, and MACS3-br and MACS3-LN (32).…”

“…We next sought to determine whether viruses isolated from the brain exhibit a higher capacity to cross the BBB than virus isolated from lymphoid tissues. To address this issue, we compared the transmigration capacities of pairs of primary viruses isolated from the same AIDS patients with dementia, either from the brain (frontal lobe) or from lymphoid tissues (spleen or lymph node) on April 8, 2019 by guest http://jvi.asm.org/ (32). Isolated viruses were amplified in CD8-depleted peripheral blood mononuclear cells as described previously (32).…”