ABSTRACT
Macrophages play a significant role in HIV infection and contribute to pathogenesis of comorbidities as well as establishment of the viral reservoir in people living with HIV. While CD4+ T cells are considered the main targets of HIV infection, infected macrophages resist the cytopathic effects of infection, contributing to the persistent HIV reservoir. Furthermore, activated macrophages drive inflammation and contribute to the development of comorbidities, including HIV-associated CNS dysfunction. Better understanding the role of macrophages in HIV infection, persistence, and comorbidities can lead to development of innovative therapeutic strategies to address HIV-related outcomes in people living with HIV. In October 2021, the National Institute of Mental Health and the Ragon Institute of MGH, MIT, and Harvard conducted a virtual meeting on role of macrophages in HIV infection, pathogenesis, and cure. This review article captures the key highlights from this meeting and provides an overview of interests and activities of various NIH institutes involved in supporting research on macrophages and HIV.
Subject(s)
HIV Infections , Humans , HIV Infections/drug therapy , Virus Latency , Macrophages/pathology , CD4-Positive T-LymphocytesABSTRACT
Respiratory syncytial virus (RSV) infects polarized epithelia, which have tightly regulated trafficking because of the separation and maintenance of the apical and basolateral membranes. Previously we established a link between the apical recycling endosome (ARE) and the assembly of RSV. The current studies tested the role of a major ARE-associated protein, Rab11 family interacting protein 2 (FIP2) in the virus life cycle. A dominant-negative form of FIP2 lacking its N-terminal C2 domain reduced the supernatant-associated RSV titer 1,000-fold and also caused the cell-associated virus titer to increase. These data suggested that the FIP2 C2 mutant caused a failure at the final budding step in the virus life cycle. Additionally, truncation of the Rab-binding domain from FIP2 caused its accumulation into mature filamentous virions. RSV budding was independent of the ESCRT machinery, the only well-defined budding mechanism for enveloped RNA viruses. Therefore, RSV uses a virus budding mechanism that is controlled by FIP2.
Subject(s)
Carrier Proteins/physiology , Membrane Proteins/physiology , Respiratory Syncytial Virus, Human/growth & development , Respiratory Syncytial Virus, Human/physiology , ATPases Associated with Diverse Cellular Activities , Adenosine Triphosphatases/genetics , Adenosine Triphosphatases/physiology , Animals , Carrier Proteins/genetics , Cell Line , Dogs , Endosomal Sorting Complexes Required for Transport , Endosomes/physiology , Endosomes/virology , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Host-Pathogen Interactions , Humans , Membrane Proteins/genetics , Mutation , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Respiratory Syncytial Virus, Human/genetics , Respiratory Syncytial Virus, Human/pathogenicity , Transfection , Vacuolar Proton-Translocating ATPases , Vesicular Transport Proteins/genetics , Vesicular Transport Proteins/physiology , Viral Matrix Proteins/genetics , Viral Matrix Proteins/physiology , Virus Assembly , Virus Shedding , rab GTP-Binding ProteinsABSTRACT
The HIV-1 Vpu protein is required for efficient viral release from human cells. For HIV-2, the envelope (Env) protein replaces the role of Vpu. Both Vpu and HIV-2 Env enhance virus release by counteracting an innate host-cell block within human cells that is absent in African green monkey (AGM) cells. Here we identify calcium-modulating cyclophilin ligand (CAML) as a Vpu-interacting host factor that restricts HIV-1 release. Expression of human CAML (encoded by CAMLG) in AGM cells conferred a strong restriction of virus release that was reversed by Vpu and HIV-2 Env, suggesting that CAML is the mechanistic link between these two viral regulators. Depletion of CAML in human cells eliminated the need for Vpu in enhancing HIV-1 and murine leukemia virus release. These results point to CAML as a Vpu-sensitive host restriction factor that inhibits HIV release from human cells. The ability of CAML to inhibit virus release should illuminate new therapeutic strategies against HIV.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , HIV-1/metabolism , Human Immunodeficiency Virus Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Adaptor Proteins, Signal Transducing/genetics , Animals , COS Cells , Cell Line , Chlorocebus aethiops , Electroporation , Gene Deletion , Green Fluorescent Proteins/metabolism , HIV-1/genetics , HeLa Cells , Human Immunodeficiency Virus Proteins/genetics , Human Immunodeficiency Virus Proteins/ultrastructure , Humans , Ligands , Plasmids , T-Lymphocytes/ultrastructure , T-Lymphocytes/virology , Transfection , Viral Regulatory and Accessory Proteins/genetics , Viral Regulatory and Accessory Proteins/ultrastructureABSTRACT
The HIV-1 accessory gene product Vpu is required for efficient viral particle release from infected human cells. The mechanism by which Vpu enhances particle assembly or release is not yet defined. Here, we identify an intracellular site that is critical for Vpu-mediated enhancement of particle release. Vpu was found to co-localize with markers for the pericentriolar recycling endosome. Expression of dominant negative mutants of Rab11a and myosin Vb that disrupt protein sorting through the recycling endosome abrogated the ability of Vpu to augment particle release. Remarkably, the effects of blocking recycling endosome function on HIV particle release were demonstrable only in human cell lines known to be responsive to Vpu, while no effect on particle release was seen in African green monkey cells. Inhibition of recycling endosome function in human cells also blocked the ability of HIV-2 envelope to enhance particle release. These studies indicate that Vpu and HIV-2 envelope glycoprotein enhance particle release via a common mechanism that requires the activity of the pericentriolar recycling endosome.
Subject(s)
Centrosome/metabolism , Endosomes/metabolism , HIV-1/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Animals , COS Cells , Cell Line, Tumor , Chlorocebus aethiops , HIV-1/genetics , HeLa Cells , Human Immunodeficiency Virus Proteins , Humans , Immunohistochemistry , Jurkat Cells , Microscopy, Confocal , Myosin Heavy Chains , Myosin Type V , Myosins/genetics , Myosins/metabolism , Viral Regulatory and Accessory Proteins/genetics , rab GTP-Binding Proteins/genetics , rab GTP-Binding Proteins/metabolismABSTRACT
Human cells resist viral infections by a variety of mechanisms. Viruses must overcome host cell restrictions to successfully reproduce their genetic material. Here, we identify a host restriction to viral replication that acts at the stage of particle assembly. Viral protein U (Vpu) is an HIV-1 accessory protein that enhances particle assembly and release in most human cells, but not in simian cells. By using human-simian cell heterokaryons, we show that the inhibition of assembly in human cells is dominant. Vpu overcomes the block to assembly in human cells and in human-simian heterokaryons. The HIV-1 vpu gene may have evolved to counteract an assembly restriction that is present in human cells.
Subject(s)
HIV-1/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Virus Replication , Animals , COS Cells , Cell Fusion , Cell Line , Chlorocebus aethiops , Gene Products, gag/physiology , HeLa Cells , Human Immunodeficiency Virus Proteins , Humans , Phenotype , Plasmids/metabolism , Polyethylene Glycols/chemistry , Time Factors , Transfection , Vero Cells , Viral Proteins/physiologyABSTRACT
Human immunodeficiency virus type-1 (HIV-1) infection dramatically increases the risk of development of Kaposi's sarcoma (KS) in individuals infected with Kaposi's sarcoma-associated herpesvirus (KSHV). In a primary effusion lymphoma (PEL) tissue culture model system, HIV-1 replication potently induced the lytic replication of KSHV and led to the secretion of soluble factors capable of inducing lytic KSHV replication in bystander cells. Here we demonstrate that HIV induces KSHV lytic replication through activation of the KSHV Rta. HIV gene expression activated the KSHV Rta promoter following viral infection or after transfection of proviral DNA. Although HIV-1 Tat has previously been implicated as an activator of KSHV lytic replication, Tat alone was unable to activate lytic replication and failed to activate the Rta promoter. We conclude that HIV activates KSHV lytic replication by inducing the KSHV Rta promoter and that factors other than HIV-1 Tat are required to mediate this effect.
