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Lou E, Vérollet C, Winkler F, Zurzolo C, Valdebenito-Silva S, Eugenin E. Tunneling nanotubes and tumor microtubes-Emerging data on their roles in intercellular communication and pathophysiology: Summary of an International FASEB Catalyst Conference October 2023. FASEB J 2024; 38:e23514. [PMID: 38466151 DOI: 10.1096/fj.202302551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 02/12/2024] [Indexed: 03/12/2024]
Abstract
In the past decade, there has been a steady rise in interest in studying novel cellular extensions and their potential roles in facilitating human diseases, including neurologic diseases, viral infectious diseases, cancer, and others. One of the exciting new aspects of this field is improved characterization and understanding of the functions and potential mechanisms of tunneling nanotubes (TNTs), which are actin-based filamentous protrusions that are structurally distinct from filopodia. TNTs form and connect cells at long distance and serve as direct conduits for intercellular communication in a wide range of cell types in vitro and in vivo. More researchers are entering this field and investigating the role of TNTs in mediating cancer cell invasion and drug resistance, cellular transfer of proteins, RNA or organelles, and intercellular spread of infectious agents, such as viruses, bacteria, and prions. Even further, the elucidation of highly functional membrane tubes called "tumor microtubes" (TMs) in incurable gliomas has further paved a new path for understanding how and why the tumor type is highly invasive at the cellular level and also resistant to standard therapies. Due to the wide-ranging and rapidly growing applicability of TNTs and TMs in pathophysiology across the spectrum of biology, it has become vital to bring researchers in the field together to discuss advances and the future of research in this important niche of protrusion biology.
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Affiliation(s)
- Emil Lou
- Division of Hematology, Oncology, and Transplantation, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Christel Vérollet
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, Centre National de la Recherche Scientifique, Université Toulouse III - Paul Sabatier (UPS), Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Toulouse, France
- International Research Laboratory (IRP) CNRS "IM-TB/HIV", Buenos Aires, Argentina
| | - Frank Winkler
- Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany
- Clinical Cooperation Unit Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Chiara Zurzolo
- Institut Pasteur, Université Paris Cité, CNRS UMR 3691, Membrane Traffic and Pathogenesis, Paris, France
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
| | | | - Eliseo Eugenin
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Galveston, Texas, USA
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2
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Xie M. Virus-Induced Cell Fusion and Syncytia Formation. Results Probl Cell Differ 2024; 71:283-318. [PMID: 37996683 DOI: 10.1007/978-3-031-37936-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Most enveloped viruses encode viral fusion proteins to penetrate host cell by membrane fusion. Interestingly, many enveloped viruses can also use viral fusion proteins to induce cell-cell fusion, both in vitro and in vivo, leading to the formation of syncytia or multinucleated giant cells (MGCs). In addition, some non-enveloped viruses encode specialized viral proteins that induce cell-cell fusion to facilitate viral spread. Overall, viruses that can induce cell-cell fusion are nearly ubiquitous in mammals. Virus cell-to-cell spread by inducing cell-cell fusion may overcome entry and post-entry blocks in target cells and allow evasion of neutralizing antibodies. However, molecular mechanisms of virus-induced cell-cell fusion remain largely unknown. Here, I summarize the current understanding of virus-induced cell fusion and syncytia formation.
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Affiliation(s)
- Maorong Xie
- Division of Infection and Immunity, UCL, London, UK.
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3
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Valdebenito S, Ono A, Rong L, Eugenin EA. The role of tunneling nanotubes during early stages of HIV infection and reactivation: implications in HIV cure. NEUROIMMUNE PHARMACOLOGY AND THERAPEUTICS 2023; 2:169-186. [PMID: 37476291 PMCID: PMC10355284 DOI: 10.1515/nipt-2022-0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/30/2022] [Indexed: 07/22/2023]
Abstract
Tunneling nanotubes (TNTs), also called cytonemes or tumor microtubes, correspond to cellular processes that enable long-range communication. TNTs are plasma membrane extensions that form tubular processes that connect the cytoplasm of two or more cells. TNTs are mostly expressed during the early stages of development and poorly expressed in adulthood. However, in disease conditions such as stroke, cancer, and viral infections such as HIV, TNTs proliferate, but their role is poorly understood. TNTs function has been associated with signaling coordination, organelle sharing, and the transfer of infectious agents such as HIV. Here, we describe the critical role and function of TNTs during HIV infection and reactivation, as well as the use of TNTs for cure strategies.
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Affiliation(s)
- Silvana Valdebenito
- Department of Neurobiology, University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | - Akira Ono
- Department of Microbiology & Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Libin Rong
- Department of Mathematics, University of Florida, Gainesville, FL, USA
| | - Eliseo A. Eugenin
- Department of Neurobiology, University of Texas Medical Branch (UTMB), Galveston, TX, USA
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Itabashi K, Miyazawa T, Uchimaru K. How Can We Prevent Mother-to-Child Transmission of HTLV-1? Int J Mol Sci 2023; 24:ijms24086961. [PMID: 37108125 PMCID: PMC10138424 DOI: 10.3390/ijms24086961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
The perception of human T-cell leukemia virus type 1 (HTlV-1) infection as a "silent disease" has recently given way to concern that its presence may be having a variety of effects. HTLV-1 is known to cause adult T-cell leukemia (ATL), an aggressive cancer of peripheral CD4 T cells; however, it is also responsible for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Most patients develop ATL as a result of HTLV-1 mother-to-child transmission. The primary route of mother-to-child transmission is through the mother's milk. In the absence of effective drug therapy, total artificial nutrition such as exclusive formula feeding is a reliable means of preventing mother-to-child transmission after birth, except for a small percentage of prenatal infections. A recent study found that the rate of mother-to-child transmission with short-term breastfeeding (within 90 days) did not exceed that of total artificial nutrition. Because these preventive measures are in exchange for the benefits of breastfeeding, clinical applications of antiretroviral drugs and immunotherapy with vaccines and neutralizing antibodies are urgently needed.
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Affiliation(s)
- Kazuo Itabashi
- Aiseikai-Memorial Ibaraki Welfare and Medical Center, Ibaraki 3100836, Japan
| | - Tokuo Miyazawa
- Department of Pediatrics, Showa University School of Medicine, Tokyo 1428666, Japan
| | - Kaoru Uchimaru
- Department of Hematology/Oncology, Research Hospital, The Institute of Medical Science, The University of Tokyo, Tokyo 1088639, Japan
- Laboratory of Tumor Cell Biology, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 1088639, Japan
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5
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Cellular Targets of HIV-1 Protease: Just the Tip of the Iceberg? Viruses 2023; 15:v15030712. [PMID: 36992421 PMCID: PMC10053624 DOI: 10.3390/v15030712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/05/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Human immunodeficiency virus 1 (HIV-1) viral protease (PR) is one of the most studied viral enzymes and a crucial antiviral target. Despite its well-characterized role in virion maturation, an increasing body of research is starting to focus on its ability to cleave host cell proteins. Such findings are apparently in contrast with the dogma of HIV-1 PR activity being restricted to the interior of nascent virions and suggest catalytic activity within the host cell environment. Given the limited amount of PR present in the virion at the time of infection, such events mainly occur during late viral gene expression, mediated by newly synthesized Gag-Pol polyprotein precursors, rather than before proviral integration. HIV-1 PR mainly targets proteins involved in three different processes: those involved in translation, those controlling cell survival, and restriction factors responsible for innate/intrinsic antiviral responses. Indeed, by cleaving host cell translation initiation factors, HIV-1 PR can impair cap-dependent translation, thus promoting IRES-mediated translation of late viral transcripts and viral production. By targeting several apoptotic factors, it modulates cell survival, thus promoting immune evasion and viral dissemination. Additionally, HIV-1 PR counteracts restriction factors incorporated in the virion that would otherwise interfere with nascent virus vitality. Thus, HIV-1 PR appears to modulate host cell function at different times and locations during its life cycle, thereby ensuring efficient viral persistency and propagation. However, we are far from having a complete picture of PR-mediated host cell modulation, which is emerging as a field that needs further investigation.
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Xu J. Dynamic analysis of a cytokine-enhanced viral infection model with infection age. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2023; 20:8666-8684. [PMID: 37161216 DOI: 10.3934/mbe.2023380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Recent studies reveal that pyroptosis is associated with the release of inflammatory cytokines which can attract more target cells to be infected. In this paper, a novel age-structured virus infection model incorporating cytokine-enhanced infection is investigated. The asymptotic smoothness of the semiflow is studied. With the help of characteristic equations and Lyapunov functionals, we have proved that both the local and global stabilities of the equilibria are completely determined by the threshold $ \mathcal{R}_0 $. The result shows that cytokine-enhanced viral infection also contributes to the basic reproduction number $ \mathcal{R}_0 $, implying that it may not be enough to eliminate the infection by decreasing the basic reproduction number of the model without considering the cytokine-enhanced viral infection mode. Numerical simulations are carried out to illustrate the theoretical results.
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Affiliation(s)
- Jinhu Xu
- School of Sciences, Xi'an University of Technology, Xi'an 710048, China
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7
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Majeed S, Adetuyi O, Borbat PP, Majharul Islam M, Ishola O, Zhao B, Georgieva ER. Insights into the oligomeric structure of the HIV-1 Vpu protein. J Struct Biol 2023; 215:107943. [PMID: 36796461 PMCID: PMC10257199 DOI: 10.1016/j.jsb.2023.107943] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/10/2023] [Accepted: 02/11/2023] [Indexed: 02/16/2023]
Abstract
The HIV-1-encoded protein Vpu forms an oligomeric ion channel/pore in membranes and interacts with host proteins to support the virus lifecycle. However, Vpu molecular mechanisms are currently not well understood. Here, we report on the Vpu oligomeric organization under membrane and aqueous conditions and provide insights into how the Vpu environment affects the oligomer formation. For these studies, we designed a maltose-binding protein (MBP)-Vpu chimera protein and produced it in E. coli in soluble form. We analyzed this protein using analytical size-exclusion chromatography (SEC), negative staining electron microscopy (nsEM), and electron paramagnetic resonance (EPR) spectroscopy. Surprisingly, we found that MBP-Vpu formed stable oligomers in solution, seemingly driven by Vpu transmembrane domain self-association. A coarse modeling of nsEM data as well as SEC and EPR data suggests that these oligomers most likely are pentamers, similar to what was reported regarding membrane-bound Vpu. We also noticed reduced MBP-Vpu oligomer stability upon reconstitution of the protein in β-DDM detergent and mixtures of lyso-PC/PG or DHPC/DHPG. In these cases, we observed greater oligomer heterogeneity, with MBP-Vpu oligomeric order generally lower than in solution; however, larger oligomers were also present. Notably, we found that in lyso-PC/PG, above a certain protein concentration, MBP-Vpu assembles into extended structures, which had not been reported for Vpu. Therefore, we captured various Vpu oligomeric forms, which can shed light on Vpu quaternary organization. Our findings could be useful in understanding Vpu organization and function in cellular membranes and could provide information regarding the biophysical properties of single-pass transmembrane proteins.
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Affiliation(s)
- Saman Majeed
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, United States
| | - Oluwatosin Adetuyi
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, United States
| | - Peter P Borbat
- Department of Chemistry and Chemical Biology and ACERT, Cornell University, Ithaca, NY 14853, United States
| | - Md Majharul Islam
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, United States
| | - Olamide Ishola
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, United States
| | - Bo Zhao
- College of Arts & Sciences Microscopy (CASM), Texas Tech University, Lubbock, TX 79409, United States
| | - Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, United States.
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Deng J, Shu H, Wang L, Wang XS. Viral dynamics with immune responses: effects of distributed delays and Filippov antiretroviral therapy. J Math Biol 2023; 86:37. [PMID: 36695964 DOI: 10.1007/s00285-023-01869-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/17/2022] [Accepted: 01/06/2023] [Indexed: 01/26/2023]
Abstract
In this paper, we propose a general viral infection model to incorporate two infection modes (virus-to-cell mode and cell-to-cell mode), the CTL immune response, and the distributed intracellular delays during the processes of viral infection, viral production, and CTLs recruitment. We investigate the existence, the uniqueness, and the global stability of three equilibria: infection-free equilibrium [Formula: see text], immune-inactivated equilibrium [Formula: see text] and immune-activated equilibrium [Formula: see text], respectively. We prove that the viral dynamics are determined by two threshold parameters: the basic reproduction number for infection [Formula: see text] and the basic reproduction number for immune response [Formula: see text]. We also numerically explore the viral dynamics beyond stability. We use bifurcation diagrams to show that increasing the delay in CTL immune cell recruitment can induce a switch in viral load from a stable constant level to sustained oscillations, and then back to a stable equilibrium. We also compare the contributions of the two infection modes to the total infection level and identify the key parameters that would affect the percentages of virus-to-cell infection and cell-to-cell infection. Finally, we explore how Filippov control can be applied in antiretroviral therapy to reduce the viral loads.
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Affiliation(s)
- Jiawei Deng
- School of Mathematics and Statistics, Shaanxi Normal University, Xi'an, 710062, People's Republic of China
| | - Hongying Shu
- School of Mathematics and Statistics, Shaanxi Normal University, Xi'an, 710062, People's Republic of China.
| | - Lin Wang
- Department of Mathematics and Statistics, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada
| | - Xiang-Sheng Wang
- Department of Mathematics, University of Louisiana at Lafayette, Lafayette, LA, 70503, USA
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9
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AlShamrani NH, Alshaikh MA, Elaiw AM, Hattaf K. Dynamics of HIV-1/HTLV-I Co-Infection Model with Humoral Immunity and Cellular Infection. Viruses 2022; 14:v14081719. [PMID: 36016341 PMCID: PMC9415130 DOI: 10.3390/v14081719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/30/2022] [Accepted: 07/30/2022] [Indexed: 12/04/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) and human T-lymphotropic virus type I (HTLV-I) are two retroviruses which infect the same target, CD4+ T cells. This type of cell is considered the main component of the immune system. Since both viruses have the same means of transmission between individuals, HIV-1-infected patients are more exposed to the chance of co-infection with HTLV-I, and vice versa, compared to the general population. The mathematical modeling and analysis of within-host HIV-1/HTLV-I co-infection dynamics can be considered a robust tool to support biological and medical research. In this study, we have formulated and analyzed an HIV-1/HTLV-I co-infection model with humoral immunity, taking into account both latent HIV-1-infected cells and HTLV-I-infected cells. The model considers two modes of HIV-1 dissemination, virus-to-cell (V-T-C) and cell-to-cell (C-T-C). We prove the nonnegativity and boundedness of the solutions of the model. We find all steady states of the model and establish their existence conditions. We utilize Lyapunov functions and LaSalle’s invariance principle to investigate the global stability of all the steady states of the model. Numerical simulations were performed to illustrate the corresponding theoretical results. The effects of humoral immunity and C-T-C transmission on the HIV-1/HTLV-I co-infection dynamics are discussed. We have shown that humoral immunity does not play the role of clearing an HIV-1 infection but it can control HIV-1 infection. Furthermore, we note that the omission of C-T-C transmission from the HIV-1/HTLV-I co-infection model leads to an under-evaluation of the basic HIV-1 mono-infection reproductive ratio.
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Affiliation(s)
- Noura H. AlShamrani
- Department of Mathematics, Faculty of Science, University of Jeddah, P.O. Box 80327, Jeddah 21589, Saudi Arabia
| | - Matuka A. Alshaikh
- Department of Mathematics, College of Science, Taif University, P.O. Box 11099, Taif 21974, Saudi Arabia
| | - Ahmed M. Elaiw
- Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
- Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut 71524, Egypt
- Correspondence: or
| | - Khalid Hattaf
- Equipe de Recherche en Modélisation et Enseignement des Mathématiques (ERMEM), Centre Régional des Métiers de l’Education et de la Formation (CRMEF), Derb Ghalef, Casablanca 20340, Morocco
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10
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Wang SF, Hung YH, Tsao CH, Chiang CY, Teoh PG, Chiang ML, Lin WH, Hsu DK, Jan HM, Lin HC, Lin CH, Liu FT, Chen HY. Galectin-3 facilitates cell-to-cell HIV-1 transmission by altering the composition of membrane lipid rafts in CD4 T cells. Glycobiology 2022; 32:760-777. [PMID: 35789267 DOI: 10.1093/glycob/cwac040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 05/28/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Galectin-3 (GAL3) is a β-galactoside-binding lectin expressed in CD4 T cells infected with human immunodeficiency virus-1 (HIV-1). GAL3 promotes HIV-1 budding by associating with ALIX and Gag p6. GAL3 has been shown to localize in membrane lipid rafts in dendritic cells and positively regulate cell migration. HIV-1 spreads between T cells by forming supramolecular structures (virological synapses [VSs]), whose integrity depends on lipid rafts. Here, we addressed the potential role of GAL3 in cell-to-cell transmission of HIV-1 in CD4 T cells. GAL3 expressed in donor cells was more important for facilitating HIV-1 cell-to-cell transfer than GAL3 expressed in target cells. GAL3 was found to be co-transferred with Gag from HIV-1-positive donor to HIV-1-negative target T cells. HIV-1 infection induced translocation of GAL3 together with Gag to the cell-cell interfaces and colocalize with GM1, where GAL3 facilitated VS formation. GAL3 regulated the coordinated transfer of Gag and flotillin-1 into plasma membrane fractions. Finally, depletion of GAL3 reduced the cholesterol levels in membrane lipid rafts in CD4 T cells. These findings provide evidence that endogenous GAL3 stimulates lipid raft components and facilitates intercellular HIV-1 transfer among CD4 T cells, offering another pathway by which GAL3 regulates HIV-1 infection. These findings may inform the treatment of HIV-1 infection based on targeting GAL3 to modulate lipid rafts.
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Affiliation(s)
- Sheng-Fan Wang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Hsien Hung
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ching-Han Tsao
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Ph.D. Program in Translational Medicine, Kaohsiung Medical University and Academia Sinica, Taiwan
| | - Cho-Ying Chiang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Pak-Guan Teoh
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Meng-Lin Chiang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Wei-Han Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Daniel K Hsu
- Department of Dermatology, University of California Davis, California, USA
| | - Hau-Ming Jan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsiu-Chu Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chun-Hung Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Fu-Tong Liu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Department of Dermatology, University of California Davis, California, USA
| | - Huan-Yuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Department of Dermatology, University of California Davis, California, USA
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Unique Mode of Antiviral Action of a Marine Alkaloid against Ebola Virus and SARS-CoV-2. Viruses 2022; 14:v14040816. [PMID: 35458549 PMCID: PMC9028129 DOI: 10.3390/v14040816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/24/2022] [Accepted: 04/02/2022] [Indexed: 11/16/2022] Open
Abstract
Lamellarin α 20-sulfate is a cell-impenetrable marine alkaloid that can suppress infection that is mediated by the envelope glycoprotein of human immunodeficiency virus type 1. We explored the antiviral action and mechanisms of this alkaloid against emerging enveloped RNA viruses that use endocytosis for infection. The alkaloid inhibited the infection of retroviral vectors that had been pseudotyped with the envelope glycoprotein of Ebola virus and SARS-CoV-2. The antiviral effects of lamellarin were independent of the retrovirus Gag-Pol proteins. Interestingly, although heparin and dextran sulfate suppressed the cell attachment of vector particles, lamellarin did not. In silico structural analyses of the trimeric glycoprotein of the Ebola virus disclosed that the principal lamellarin-binding site is confined to a previously unappreciated cavity near the NPC1-binding site and fusion loop, whereas those for heparin and dextran sulfate were dispersed across the attachment and fusion subunits of the glycoproteins. Notably, lamellarin binding to this cavity was augmented under conditions where the pH was 5.0. These results suggest that the final action of the alkaloid against Ebola virus is specific to events following endocytosis, possibly during conformational glycoprotein changes in the acidic environment of endosomes. Our findings highlight the unique biological and physicochemical features of lamellarin α 20-sulfate and should lead to the further use of broadly reactive antivirals to explore the structural mechanisms of virus replication.
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Perez-Zsolt D, Raïch-Regué D, Muñoz-Basagoiti J, Aguilar-Gurrieri C, Clotet B, Blanco J, Izquierdo-Useros N. HIV-1 trans-Infection Mediated by DCs: The Tip of the Iceberg of Cell-to-Cell Viral Transmission. Pathogens 2021; 11:39. [PMID: 35055987 PMCID: PMC8778849 DOI: 10.3390/pathogens11010039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 02/07/2023] Open
Abstract
HIV-1 cell-to-cell transmission is key for an effective viral replication that evades immunity. This highly infectious mechanism is orchestrated by different cellular targets that utilize a wide variety of processes to efficiently transfer HIV-1 particles. Dendritic cells (DCs) are the most potent antigen presenting cells that initiate antiviral immune responses, but are also the cells with highest capacity to transfer HIV-1. This mechanism, known as trans-infection, relies on the capacity of DCs to capture HIV-1 particles via lectin receptors such as the sialic acid-binding I-type lectin Siglec-1/CD169. The discovery of the molecular interaction of Siglec-1 with sialylated lipids exposed on HIV-1 membranes has enlightened how this receptor can bind to several enveloped viruses. The outcome of these interactions can either mount effective immune responses, boost the productive infection of DCs and favour innate sensing, or fuel viral transmission via trans-infection. Here we review these scenarios focusing on HIV-1 and other enveloped viruses such as Ebola virus or SARS-CoV-2.
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Affiliation(s)
- Daniel Perez-Zsolt
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
| | - Dàlia Raïch-Regué
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
| | - Jordana Muñoz-Basagoiti
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
| | - Carmen Aguilar-Gurrieri
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
| | - Bonaventura Clotet
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
- Infectious Diseases and Immunity Department, Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), 08500 Vic, Spain
| | - Julià Blanco
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
- Infectious Diseases and Immunity Department, Faculty of Medicine, University of Vic-Central University of Catalonia (UVic-UCC), 08500 Vic, Spain
- Germans Trias i Pujol Research Institute (IGTP), Can Ruti Campus, 08916 Badalona, Spain
| | - Nuria Izquierdo-Useros
- IrsiCaixa AIDS Research Institute, Can Ruti Campus, 08916 Badalona, Spain; (D.P.-Z.); (D.R.-R.); (J.M.-B.); (C.A.-G.); (B.C.); (J.B.)
- Germans Trias i Pujol Research Institute (IGTP), Can Ruti Campus, 08916 Badalona, Spain
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13
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Bystander CD4 T-cell death is inhibited by broadly neutralizing anti-HIV antibodies only at levels blocking cell-to-cell viral transmission. J Biol Chem 2021; 297:101098. [PMID: 34418431 PMCID: PMC8446805 DOI: 10.1016/j.jbc.2021.101098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 06/28/2021] [Accepted: 08/17/2021] [Indexed: 11/23/2022] Open
Abstract
The progressive loss of CD4+ T cells during HIV infection of lymphoid tissues involves both the apoptotic death of activated and productively infected CD4 T cells and the pyroptotic death of large numbers of resting and abortively infected bystander CD4 T cells. HIV spreads both through cellular release of virions and cell-to-cell transmission involving the formation of virological synapses. Cell-to-cell transmission results in high-level transfer of large quantities of virions to the target cell exceeding that achieved with cell-free virions. Broadly neutralizing anti-HIV antibodies (bNAbs) binding to HIV envelope protein capably block cell-free virus spread, and when added at higher concentrations can also interdict cell-to-cell transmission. Exploiting these distinct dose–response differences, we now show that four different bNAbs block the pyroptotic death of bystander cells, but only when added at concentrations sufficient to block cell-to-cell transmission. These findings further support the conclusion that HIV killing of abortively infected bystander CD4 T cells requires cell-to-cell transfer of virions. As bNAbs attract more interest as potential therapeutics, it will be important to consider the higher concentrations of these antibodies required to block the inflammatory death of bystander CD4 T cells.
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14
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Guo T, Qiu Z, Shen M, Rong L. Dynamics of a new HIV model with the activation status of infected cells. J Math Biol 2021; 82:51. [PMID: 33860365 PMCID: PMC8049625 DOI: 10.1007/s00285-021-01604-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/28/2021] [Accepted: 04/03/2021] [Indexed: 11/06/2022]
Abstract
The activation status can dictate the fate of an HIV-infected CD4+ T cell. Infected cells with a low level of activation remain latent and do not produce virus, while cells with a higher level of activation are more productive and thus likely to transfer more virions to uninfected cells during cell-to-cell transmission. How the activation status of infected cells affects HIV dynamics under antiretroviral therapy remains unclear. We develop a new mathematical model that structures the population of infected cells continuously according to their activation status. The effectiveness of antiretroviral drugs in blocking cell-to-cell viral transmission decreases as the level of activation of infected cells increases because the more virions are transferred from infected to uninfected cells during cell-to-cell transmission, the less effectively the treatment is able to inhibit the transmission. The basic reproduction number \documentclass[12pt]{minimal}
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\begin{document}$$R_{0}$$\end{document}R0 of the model is shown to determine the existence and stability of the equilibria. Using the principal spectral theory and comparison principle, we show that the infection-free equilibrium is locally and globally asymptotically stable when \documentclass[12pt]{minimal}
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\begin{document}$$R_{0}$$\end{document}R0 is less than one. By constructing Lyapunov functional, we prove that the infected equilibrium is globally asymptotically stable when \documentclass[12pt]{minimal}
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\begin{document}$$R_{0}$$\end{document}R0 is greater than one. Numerical investigation shows that even when treatment can completely block cell-free virus infection, virus can still persist due to cell-to-cell transmission. The random switch between infected cells with different activation levels can also contribute to the replenishment of the latent reservoir, which is considered as a major barrier to viral eradication. This study provides a new modeling framework to study the observations, such as the low viral load persistence, extremely slow decay of latently infected cells and transient viral load measurements above the detection limit, in HIV-infected patients during suppressive antiretroviral therapy.
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Affiliation(s)
- Ting Guo
- School of Science, Nanjing University of Science and Technology, Nanjing, 210094, China.,Department of Mathematics, University of Florida, Gainesville, FL, 32611, USA
| | - Zhipeng Qiu
- Center for Basic Teaching and Experiment, Nanjing University of Science and Technology Jiangyin Campus, Jiangyin, 214443, China
| | - Mingwang Shen
- Department of Epidemiology and Biostatistics, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Libin Rong
- Department of Mathematics, University of Florida, Gainesville, FL, 32611, USA.
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15
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Hikichi Y, Van Duyne R, Pham P, Groebner JL, Wiegand A, Mellors JW, Kearney MF, Freed EO. Mechanistic Analysis of the Broad Antiretroviral Resistance Conferred by HIV-1 Envelope Glycoprotein Mutations. mBio 2021; 12:e03134-20. [PMID: 33436439 PMCID: PMC7844542 DOI: 10.1128/mbio.03134-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023] Open
Abstract
Despite the effectiveness of antiretroviral (ARV) therapy, virological failure can occur in some HIV-1-infected patients in the absence of mutations in drug target genes. We previously reported that, in vitro, the lab-adapted HIV-1 NL4-3 strain can acquire resistance to the integrase inhibitor dolutegravir (DTG) by acquiring mutations in the envelope glycoprotein (Env) that enhance viral cell-cell transmission. In this study, we investigated whether Env-mediated drug resistance extends to ARVs other than DTG and whether it occurs in other HIV-1 isolates. We demonstrate that Env mutations can reduce susceptibility to multiple classes of ARVs and also increase resistance to ARVs when coupled with target-gene mutations. We observe that the NL4-3 Env mutants display a more stable and closed Env conformation and lower rates of gp120 shedding than the WT virus. We also selected for Env mutations in clinically relevant HIV-1 isolates in the presence of ARVs. These Env mutants exhibit reduced susceptibility to DTG, with effects on replication and Env structure that are HIV-1 strain dependent. Finally, to examine a possible in vivo relevance of Env-mediated drug resistance, we performed single-genome sequencing of plasma-derived virus from five patients failing an integrase inhibitor-containing regimen. This analysis revealed the presence of several mutations in the highly conserved gp120-gp41 interface despite low frequency of resistance mutations in integrase. These results suggest that mutations in Env that enhance the ability of HIV-1 to spread via a cell-cell route may increase the opportunity for the virus to acquire high-level drug resistance mutations in ARV target genes.IMPORTANCE Although combination antiretroviral (ARV) therapy is highly effective in controlling the progression of HIV disease, drug resistance can be a major obstacle. Recent findings suggest that resistance can develop without ARV target gene mutations. We previously reported that mutations in the HIV-1 envelope glycoprotein (Env) confer resistance to an integrase inhibitor. Here, we investigated the mechanism of Env-mediated drug resistance and the possible contribution of Env to virological failure in vivo We demonstrate that Env mutations can reduce sensitivity to major classes of ARVs in multiple viral isolates and define the effect of the Env mutations on Env subunit interactions. We observed that many Env mutations accumulated in individuals failing integrase inhibitor therapy despite a low frequency of resistance mutations in integrase. Our findings suggest that broad-based Env-mediated drug resistance may impact therapeutic strategies and provide clues toward understanding how ARV-treated individuals fail therapy without acquiring mutations in drug target genes.
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Affiliation(s)
- Yuta Hikichi
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Rachel Van Duyne
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Phuong Pham
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Jennifer L Groebner
- Translational Research Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Ann Wiegand
- Translational Research Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - John W Mellors
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mary F Kearney
- Translational Research Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
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16
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Analysis of a within-host HIV/HTLV-I co-infection model with immunity. Virus Res 2020; 295:198204. [PMID: 33157165 DOI: 10.1016/j.virusres.2020.198204] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 10/07/2020] [Accepted: 10/16/2020] [Indexed: 12/16/2022]
Abstract
Human immunodeficiency virus (HIV) and human T-lymphotropic virus type I (HTLV-I) are two retroviruses that attack the immune cells and impair their functions. Both HIV and HTLV-I can be transmitted between individuals through direct contact with certain body fluids from infected individuals. Therefore, a person can be co-infected with both viruses. HIV causes acquired immunodeficiency syndrome, while HTLV-I is the causative agent for adult T-cell leukemia and HTLV-I-associated myelopathy/tropical spastic paraparesis. Several mathematical models have been developed in the literature to describe the within-host dynamics of HIV and HTLV-I mono-infections. However, modeling a within-host dynamics of HIV/HTLV-I co-infection has not been involved. In the present paper, we are concerned to formulate and analyze a new HIV/HTLV co-infection model under the effect of Cytotoxic T lymphocytes (CTLs) immune response. The model describes the interaction between susceptible CD4+T cells, silent HIV-infected cells, active HIV-infected cells, silent HTLV-infected cells, Tax-expressing HTLV-infected cells, free HIV particles, HIV-specific CTLs and HTLV-specific CTLs. The HIV can spread by two routes of transmission, virus-to-cell and cell-to-cell. On the other side, HTLV-I has two modes of transmission, (i) horizontal transmission via direct cell-to-cell contact, and (ii) vertical transmission through mitotic division of Tax-expressing HTLV-infected cells. The well-posedness of the model is established by showing that the solutions of the model are nonnegative and bounded. We define a set of threshold parameters which govern the existence and stability of all equilibria of the model. We explore the global asymptotic stability of all equilibria by utilizing Lyapunov function and LaSalle's invariance principle. We have presented numerical simulations to justify the applicability and effectiveness of the theoretical results. In addition, we evaluate the effect of HTLV-I infection on the HIV dynamics and vice versa.
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17
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Geng Y, Xu J. Stability and bifurcation analysis for a delayed viral infection model with full logistic proliferation. INT J BIOMATH 2020. [DOI: 10.1142/s1793524520500333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, we study a delayed viral infection model with cellular infection and full logistic proliferations for both healthy and infected cells. The global asymptotic stabilities of the equilibria are studied by constructing Lyapunov functionals. Moreover, we investigated the existence of Hopf bifurcation at the infected equilibrium by regarding the possible combination of the two delays as bifurcation parameters. The results show that time delays may destabilize the infected equilibrium and lead to Hopf bifurcation. Finally, numerical simulations are carried out to illustrate the main results and explore the dynamics including Hopf bifurcation and stability switches.
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Affiliation(s)
- Yan Geng
- School of Science, Xi’an Polytechnic University, Xi’an 710048, Shaanxi, P. R. China
| | - Jinhu Xu
- School of Sciences, Xi’an University of Technology, Xi’an 710049, Shaanxi, P. R. China
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18
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Modeling the role of macrophages in HIV persistence during antiretroviral therapy. J Math Biol 2020; 81:369-402. [PMID: 32583031 DOI: 10.1007/s00285-020-01513-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 06/13/2020] [Indexed: 12/17/2022]
Abstract
HIV preferentially infects activated CD4+ T cells. Current antiretroviral therapy cannot eradicate the virus. Viral infection of other cells such as macrophages may contribute to viral persistence during antiretroviral therapy. In addition to cell-free virus infection, macrophages can also get infected when engulfing infected CD4+ T cells as innate immune sentinels. How macrophages affect the dynamics of HIV infection remains unclear. In this paper, we develop an HIV model that includes the infection of CD4+ T cells and macrophages via cell-free virus infection and cell-to-cell viral transmission. We derive the basic reproduction number and obtain the local and global stability of the steady states. Sensitivity and viral dynamics simulations show that even when the infection of CD4+ T cells is completely blocked by therapy, virus can still persist and the steady-state viral load is not sensitive to the change of treatment efficacy. Analysis of the relative contributions to viral replication shows that cell-free virus infection leads to the majority of macrophage infection. Viral transmission from infected CD4+ T cells to macrophages during engulfment accounts for a small fraction of the macrophage infection and has a negligible effect on the total viral production. These results suggest that macrophage infection can be a source contributing to HIV persistence during suppressive therapy. Improving drug efficacies in heterogeneous target cells is crucial for achieving HIV eradication in infected individuals.
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19
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Grossman Z, Singh NJ, Simonetti FR, Lederman MM, Douek DC, Deeks SG. 'Rinse and Replace': Boosting T Cell Turnover To Reduce HIV-1 Reservoirs. Trends Immunol 2020; 41:466-480. [PMID: 32414695 DOI: 10.1016/j.it.2020.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 12/22/2022]
Abstract
Latent HIV-1 persists indefinitely during antiretroviral therapy (ART) as an integrated silent genome in long-lived memory CD4+ T cells. In untreated infections, immune activation increases the turnover of intrinsically long-lived provirus-containing CD4+ T cells. Those are 'washed out' as a result of their activation, which when coupled to viral protein expression can facilitate local inflammation and recruitment of uninfected cells to activation sites, causing latently infected cells to compete for survival. De novo infection can counter this washout. During ART, inflammation and CD4+ T cell activation wane, resulting in reduced cell turnover and a persistent reservoir. We propose accelerating reservoir washout during ART by triggering sequential waves of polyclonal CD4+ T cell activation while simultaneously enhancing virus protein expression. Reservoir reduction as an adjunct to other therapies might achieve lifelong viral control.
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Affiliation(s)
- Zvi Grossman
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA; Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Nevil J Singh
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Francesco R Simonetti
- 'L. Sacco' Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | | | - Daniel C Douek
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Steven G Deeks
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
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20
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Virgilio MC, Collins KL. The Impact of Cellular Proliferation on the HIV-1 Reservoir. Viruses 2020; 12:v12020127. [PMID: 31973022 PMCID: PMC7077244 DOI: 10.3390/v12020127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/16/2020] [Accepted: 01/18/2020] [Indexed: 12/25/2022] Open
Abstract
Human immunodeficiency virus (HIV) is a chronic infection that destroys the immune system in infected individuals. Although antiretroviral therapy is effective at preventing infection of new cells, it is not curative. The inability to clear infection is due to the presence of a rare, but long-lasting latent cellular reservoir. These cells harboring silent integrated proviral genomes have the potential to become activated at any moment, making therapy necessary for life. Latently-infected cells can also proliferate and expand the viral reservoir through several methods including homeostatic proliferation and differentiation. The chromosomal location of HIV proviruses within cells influences the survival and proliferative potential of host cells. Proliferating, latently-infected cells can harbor proviruses that are both replication-competent and defective. Replication-competent proviral genomes contribute to viral rebound in an infected individual. The majority of available techniques can only assess the integration site or the proviral genome, but not both, preventing reliable evaluation of HIV reservoirs.
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Affiliation(s)
- Maria C. Virgilio
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA;
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kathleen L. Collins
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA;
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA
- Correspondence:
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21
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Zhang T, Wang J, Li Y, Jiang Z, Han X. Dynamics analysis of a delayed virus model with two different transmission methods and treatments. ADVANCES IN DIFFERENCE EQUATIONS 2020; 2020:1. [PMID: 32226454 PMCID: PMC7100214 DOI: 10.1186/s13662-019-2438-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 11/29/2019] [Indexed: 05/07/2023]
Abstract
In this paper, a delayed virus model with two different transmission methods and treatments is investigated. This model is a time-delayed version of the model in (Zhang et al. in Comput. Math. Methods Med. 2015:758362, 2015). We show that the virus-free equilibrium is locally asymptotically stable if the basic reproduction number is smaller than one, and by regarding the time delay as a bifurcation parameter, the existence of local Hopf bifurcation is investigated. The results show that time delay can change the stability of the endemic equilibrium. Finally, we give some numerical simulations to illustrate the theoretical findings.
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Affiliation(s)
- Tongqian Zhang
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, P.R. China
| | - Junling Wang
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, P.R. China
| | - Yuqing Li
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, P.R. China
| | - Zhichao Jiang
- Fundamental Science Department, North China Institute of Aerospace Engineering, Langfang, P.R. China
| | - Xiaofeng Han
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, P.R. China
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22
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Grossman Z. Immunological Paradigms, Mechanisms, and Models: Conceptual Understanding Is a Prerequisite to Effective Modeling. Front Immunol 2019; 10:2522. [PMID: 31749803 PMCID: PMC6848063 DOI: 10.3389/fimmu.2019.02522] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 10/10/2019] [Indexed: 12/18/2022] Open
Abstract
Most mathematical models that describe the individual or collective actions of cells aim at creating faithful representations of limited sets of data in a self-consistent manner. Consistency with relevant physiological rules pertaining to the greater picture is rarely imposed. By themselves, such models have limited predictive or even explanatory value, contrary to standard claims. Here I try to show that a more critical examination of currently held paradigms is necessary and could potentially lead to models that pass the test of time. In considering the evolution of paradigms over the past decades I focus on the “smart surveillance” theory of how T cells can respond differentially, individually and collectively, to both self- and foreign antigens depending on various “contextual” parameters. The overall perspective is that physiological messages to cells are encoded not only in the biochemical connections of signaling molecules to the cellular machinery but also in the magnitude, kinetics, and in the time- and space-contingencies, of sets of stimuli. By rationalizing the feasibility of subthreshold interactions, the “dynamic tuning hypothesis,” a central component of the theory, set the ground for further theoretical and experimental explorations of dynamically regulated immune tolerance, homeostasis and diversity, and of the notion that lymphocytes participate in nonclassical physiological functions. Some of these efforts are reviewed. Another focus of this review is the concomitant regulation of immune activation and homeostasis through the operation of a feedback mechanism controlling the balance between renewal and differentiation of activated cells. Different perspectives on the nature and regulation of chronic immune activation in HIV infection have led to conflicting models of HIV pathogenesis—a major area of research for theoretical immunologists over almost three decades—and can have profound impact on ongoing HIV cure strategies. Altogether, this critical review is intended to constructively influence the outlook of prospective model builders and of interested immunologists on the state of the art and to encourage conceptual work.
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Affiliation(s)
- Zvi Grossman
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Showa SP, Nyabadza F, Hove-Musekwa SD. On the efficiency of HIV transmission: Insights through discrete time HIV models. PLoS One 2019; 14:e0222574. [PMID: 31532803 PMCID: PMC6750597 DOI: 10.1371/journal.pone.0222574] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 09/03/2019] [Indexed: 11/18/2022] Open
Abstract
There are different views on which of the two forms of viral spread is more efficient in vivo between cell-free and cell-associated virus. In this study, discrete time human immunodeficiency virus models are formulated and analysed with the goal of determining the form of viral spread that is more efficient in vivo. It is shown that on its own, cell-free viral spread cannot sustain an infection owing to the low infectivity of cell-free virus and cell-associated virus can sustain an infection because of the high infectivity of cell-associated virus. When acting concurrently, cell-associated virus is more efficient in spreading the infection upon exposure to the virus. However, in the long term, the two forms of viral spread contribute almost equally. Both forms of viral spread are shown to be able to initiate an infection.
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Affiliation(s)
- Sarudzai P Showa
- Department of Applied Mathematics, National University of Science and Technology, Bulawayo, Zimbabwe
| | - Farai Nyabadza
- Department of Mathematics and Applied Mathematics, Auckland Park Campus, University of Johannesburg, Johannesburg, South Africa
| | - Senelani D Hove-Musekwa
- Department of Applied Mathematics, National University of Science and Technology, Bulawayo, Zimbabwe
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24
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Raezah AA, Elaiw AM, Alofi BS. Global Properties of Latent Virus Dynamics Models with Immune Impairment and Two Routes of Infection. High Throughput 2019; 8:ht8020016. [PMID: 31163653 PMCID: PMC6630556 DOI: 10.3390/ht8020016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/19/2019] [Accepted: 05/15/2019] [Indexed: 11/24/2022] Open
Abstract
This paper studies the global stability of viral infection models with CTL immune impairment. We incorporate both productively and latently infected cells. The models integrate two routes of transmission, cell-to-cell and virus-to-cell. In the second model, saturated virus–cell and cell–cell incidence rates are considered. The basic reproduction number is derived and two steady states are calculated. We first establish the nonnegativity and boundedness of the solutions of the system, then we investigate the global stability of the steady states. We utilize the Lyapunov method to prove the global stability of the two steady states. We support our theorems by numerical simulations.
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Affiliation(s)
- Aeshah A Raezah
- Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
- Department of Mathematics, Faculty of Science, King Khalid University, P.O. Box 25145, Abha 61466, Saudi Arabia.
| | - Ahmed M Elaiw
- Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
| | - Badria S Alofi
- Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
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25
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Accounting for Space—Quantification of Cell-To-Cell Transmission Kinetics Using Virus Dynamics Models. Viruses 2018; 10:v10040200. [PMID: 29673154 PMCID: PMC5923494 DOI: 10.3390/v10040200] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/11/2018] [Accepted: 04/12/2018] [Indexed: 12/12/2022] Open
Abstract
Mathematical models based on ordinary differential equations (ODE) that describe the population dynamics of viruses and infected cells have been an essential tool to characterize and quantify viral infection dynamics. Although an important aspect of viral infection is the dynamics of viral spread, which includes transmission by cell-free virions and direct cell-to-cell transmission, models used so far ignored cell-to-cell transmission completely, or accounted for this process by simple mass-action kinetics between infected and uninfected cells. In this study, we show that the simple mass-action approach falls short when describing viral spread in a spatially-defined environment. Using simulated data, we present a model extension that allows correct quantification of cell-to-cell transmission dynamics within a monolayer of cells. By considering the decreasing proportion of cells that can contribute to cell-to-cell spread with progressing infection, our extension accounts for the transmission dynamics on a single cell level while still remaining applicable to standard population-based experimental measurements. While the ability to infer the proportion of cells infected by either of the transmission modes depends on the viral diffusion rate, the improved estimates obtained using our novel approach emphasize the need to correctly account for spatial aspects when analyzing viral spread.
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26
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Abstract
While HIV-1 infection of target cells with cell-free viral particles has been largely documented, intercellular transmission through direct cell-to-cell contact may be a predominant mode of propagation in host. To spread, HIV-1 infects cells of the immune system and takes advantage of their specific particularities and functions. Subversion of intercellular communication allows to improve HIV-1 replication through a multiplicity of intercellular structures and membrane protrusions, like tunneling nanotubes, filopodia, or lamellipodia-like structures involved in the formation of the virological synapse. Other features of immune cells, like the immunological synapse or the phagocytosis of infected cells are hijacked by HIV-1 and used as gateways to infect target cells. Finally, HIV-1 reuses its fusogenic capacity to provoke fusion between infected donor cells and target cells, and to form infected syncytia with high capacity of viral production and improved capacities of motility or survival. All these modes of cell-to-cell transfer are now considered as viral mechanisms to escape immune system and antiretroviral therapies, and could be involved in the establishment of persistent virus reservoirs in different host tissues.
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Affiliation(s)
- Lucie Bracq
- Inserm U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France.,International Associated Laboratory (LIA VirHost), Institut Pasteur Shanghai-Chinese Academy of Sciences, Shanghai, China.,International Associated Laboratory (LIA VirHost), CNRS, Université Paris-Descartes, Institut Pasteur, Paris, France
| | - Maorong Xie
- Inserm U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France.,International Associated Laboratory (LIA VirHost), CNRS, Université Paris-Descartes, Institut Pasteur, Paris, France
| | - Serge Benichou
- Inserm U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France.,International Associated Laboratory (LIA VirHost), Institut Pasteur Shanghai-Chinese Academy of Sciences, Shanghai, China.,International Associated Laboratory (LIA VirHost), CNRS, Université Paris-Descartes, Institut Pasteur, Paris, France
| | - Jérôme Bouchet
- Inserm U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris-Descartes, Sorbonne Paris-Cité, Paris, France.,International Associated Laboratory (LIA VirHost), CNRS, Université Paris-Descartes, Institut Pasteur, Paris, France
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27
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The pentameric complex drives immunologically covert cell-cell transmission of wild-type human cytomegalovirus. Proc Natl Acad Sci U S A 2017; 114:6104-6109. [PMID: 28533400 DOI: 10.1073/pnas.1704809114] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human cytomegalovirus (HCMV) strains that have been passaged in vitro rapidly acquire mutations that impact viral growth. These laboratory-adapted strains of HCMV generally exhibit restricted tropism, produce high levels of cell-free virus, and develop susceptibility to natural killer cells. To permit experimentation with a virus that retained a clinically relevant phenotype, we reconstructed a wild-type (WT) HCMV genome using bacterial artificial chromosome technology. Like clinical virus, this genome proved to be unstable in cell culture; however, propagation of intact virus was achieved by placing the RL13 and UL128 genes under conditional expression. In this study, we show that WT-HCMV produces extremely low titers of cell-free virus but can efficiently infect fibroblasts, epithelial, monocyte-derived dendritic, and Langerhans cells via direct cell-cell transmission. This process of cell-cell transfer required the UL128 locus, but not the RL13 gene, and was significantly less vulnerable to the disruptive effects of IFN, cellular restriction factors, and neutralizing antibodies compared with cell-free entry. Resistance to neutralizing antibodies was dependent on high-level expression of the pentameric gH/gL/gpUL128-131A complex, a feature of WT but not passaged strains of HCMV.
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28
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JAK-STAT Signaling Pathways and Inhibitors Affect Reversion of Envelope-Mutated HIV-1. J Virol 2017; 91:JVI.00075-17. [PMID: 28202754 DOI: 10.1128/jvi.00075-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/08/2017] [Indexed: 11/20/2022] Open
Abstract
HIV can spread by both cell-free and cell-to-cell transmission. Here, we show that many of the amino acid changes in Env that are close to the CD4 binding pocket can affect HIV replication. We generated a number of mutant viruses that were unable to infect T cells as cell-free viruses but were nevertheless able to infect certain T cell lines as cell-associated viruses, which was followed by reversion to the wild type. However, the activation of JAK-STAT signaling pathways caused the inhibition of such cell-to-cell infection as well as the reversion of multiple HIV Env mutants that displayed differences in their abilities to bind to the CD4 receptor. Specifically, two T cell activators, interleukin-2 (IL-2) and phorbol 12-myristate 13-acetate (PMA), both capable of activation of JAK-STAT pathways, were able to inhibit cell-to-cell viral transmission. In contrast, but consistent with the above result, a number of JAK-STAT and mTOR inhibitors actually promoted HIV-1 transmission and reversion. Hence, JAK-STAT signaling pathways may differentially affect the replication of a variety of HIV Env mutants in ways that differ from the role that these pathways play in the replication of wild-type viruses.IMPORTANCE Specific alterations in HIV Env close to the CD4 binding site can differentially change the ability of HIV to mediate infection for cell-free and cell-associated viruses. However, such differences are dependent to some extent on the types of target cells used. JAK-STAT signaling pathways are able to play major roles in these processes. This work sheds new light on factors that can govern HIV infection of target cells.
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Abstract
Human immunodeficiency virus type 1 (HIV-1) gives rise to a chronic infection that progressively depletes CD4(+) T lymphocytes. CD4(+) T lymphocytes play a central coordinating role in adaptive cellular and humoral immune responses, and to do so they migrate and interact within lymphoid compartments and at effector sites to mount immune responses. While cell-free virus serves as an excellent prognostic indicator for patient survival, interactions of infected T cells or virus-scavenging immune cells with uninfected T cells can greatly enhance viral spread. HIV can induce interactions between infected and uninfected T cells that are triggered by cell surface expression of viral Env, which serves as a cell adhesion molecule that interacts with CD4 on the target cell, before it acts as the viral membrane fusion protein. These interactions are called virological synapses and promote replication in the face of selective pressure of humoral immune responses and antiretroviral therapy. Other infection-enhancing cell-cell interactions occur between virus-concentrating antigen-presenting cells and recipient T cells, called infectious synapses. The exact roles that these cell-cell interactions play in each stage of infection, from viral acquisition, systemic dissemination, to chronic persistence are still being determined. Infection-promoting immune cell interactions are likely to contribute to viral persistence and enhance the ability of HIV-1 to evade adaptive immune responses.
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Affiliation(s)
- K M Law
- Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - N Satija
- Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - A M Esposito
- Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - B K Chen
- Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY, United States.
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30
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Kumberger P, Frey F, Schwarz US, Graw F. Multiscale modeling of virus replication and spread. FEBS Lett 2016; 590:1972-86. [PMID: 26878104 DOI: 10.1002/1873-3468.12095] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 01/21/2016] [Accepted: 02/07/2016] [Indexed: 01/16/2023]
Abstract
Replication and spread of human viruses is based on the simultaneous exploitation of many different host functions, bridging multiple scales in space and time. Mathematical modeling is essential to obtain a systems-level understanding of how human viruses manage to proceed through their life cycles. Here, we review corresponding advances for viral systems of large medical relevance, such as human immunodeficiency virus-1 (HIV-1) and hepatitis C virus (HCV). We will outline how the combination of mathematical models and experimental data has advanced our quantitative knowledge about various processes of these pathogens, and how novel quantitative approaches promise to fill remaining gaps.
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Affiliation(s)
- Peter Kumberger
- BioQuant-Center, Heidelberg University, Germany.,Center for Modeling and Simulation in the Biosciences (BIOMS), Heidelberg University, Germany
| | - Felix Frey
- BioQuant-Center, Heidelberg University, Germany.,Institute for Theoretical Physics, Heidelberg University, Germany
| | - Ulrich S Schwarz
- BioQuant-Center, Heidelberg University, Germany.,Institute for Theoretical Physics, Heidelberg University, Germany
| | - Frederik Graw
- BioQuant-Center, Heidelberg University, Germany.,Center for Modeling and Simulation in the Biosciences (BIOMS), Heidelberg University, Germany
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31
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Mussil B, Javed A, Töpfer K, Sauermann U, Sopper S. Increased BST2 expression during simian immunodeficiency virus infection is not a determinant of disease progression in rhesus monkeys. Retrovirology 2015; 12:92. [PMID: 26554913 PMCID: PMC4641394 DOI: 10.1186/s12977-015-0219-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/23/2015] [Indexed: 12/21/2022] Open
Abstract
Background Bone marrow stromal cell antigen 2 (BST2), also known as tetherin, HM1.24 or CD317 represents a type 2 integral membrane protein, which has been described to restrict the production of some enveloped viruses by inhibiting the virus release from the cell surface. This innate antiviral mechanism is counteracted by the HIV-1 viral factor Vpu, targeting BST2 for cellular degradation. Since antiviral BST2 activity has been mainly confirmed by in vitro data, we investigated its role in vivo on the disease progression using the SIV/macaque model for AIDS. We determined BST2 expression in PBMC and leukocyte subsets of uninfected and SIV-infected rhesus macaques by real-time PCR and flow cytometry and correlated it with disease progression and viral load. Results Compared to pre-infection levels, we found increased BST2 expression in PBMC, purified CD4+ lymphocytes and CD14+ monocytes of SIV-infected animals, which correlated with viral load. Highest BST2 levels were found in progressors and lowest levels comparable to uninfected macaques were observed in long-term non-progressors (LTNPs). During acute viremia, BST2 mRNA increased in parallel with MX1, a prototype interferon-stimulated gene. This association was maintained during the whole disease course. Conclusion The detected relationship between BST2 expression and viral load as well as with MX1 indicate a common regulation by the interferon response and suggest rather limited influence of BST2 in vivo on the disease outcome. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0219-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bianka Mussil
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Aneela Javed
- Unit of Infection Models, German Primate Centre, Goettingen, Germany. .,Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Science and Technology (NUST), H12, Islamabad, Pakistan.
| | - Katharina Töpfer
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Ulrike Sauermann
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Sieghart Sopper
- Department of Hematology and Oncology, Medical University Innsbruck, ZVG 7G5 009A, Anichstr. 35, 6020, Innsbruck, Austria. .,Tyrolean Cancer Research Institute, Innsbruck, Austria.
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32
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Precharattana M. Stochastic modeling for dynamics of HIV-1 infection using cellular automata: A review. J Bioinform Comput Biol 2015; 14:1630001. [PMID: 26620040 DOI: 10.1142/s021972001630001x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recently, the description of immune response by discrete models has emerged to play an important role to study the problems in the area of human immunodeficiency virus type 1 (HIV-1) infection, leading to AIDS. As infection of target immune cells by HIV-1 mainly takes place in the lymphoid tissue, cellular automata (CA) models thus represent a significant step in understanding when the infected population is dispersed. Motivated by these, the studies of the dynamics of HIV-1 infection using CA in memory have been presented to recognize how CA have been developed for HIV-1 dynamics, which issues have been studied already and which issues still are objectives in future studies.
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Affiliation(s)
- Monamorn Precharattana
- 1 Institute for Innovative Learning, Mahidol University, 999 Salaya, Phutthamonthon District Nakhon Pathom 73170, Thailand
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33
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Iwami S, Takeuchi JS, Nakaoka S, Mammano F, Clavel F, Inaba H, Kobayashi T, Misawa N, Aihara K, Koyanagi Y, Sato K. Cell-to-cell infection by HIV contributes over half of virus infection. eLife 2015; 4. [PMID: 26441404 PMCID: PMC4592948 DOI: 10.7554/elife.08150] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/04/2015] [Indexed: 12/14/2022] Open
Abstract
Cell-to-cell viral infection, in which viruses spread through contact of infected cell with surrounding uninfected cells, has been considered as a critical mode of virus infection. However, since it is technically difficult to experimentally discriminate the two modes of viral infection, namely cell-free infection and cell-to-cell infection, the quantitative information that underlies cell-to-cell infection has yet to be elucidated, and its impact on virus spread remains unclear. To address this fundamental question in virology, we quantitatively analyzed the dynamics of cell-to-cell and cell-free human immunodeficiency virus type 1 (HIV-1) infections through experimental-mathematical investigation. Our analyses demonstrated that the cell-to-cell infection mode accounts for approximately 60% of viral infection, and this infection mode shortens the generation time of viruses by 0.9 times and increases the viral fitness by 3.9 times. Our results suggest that even a complete block of the cell-free infection would provide only a limited impact on HIV-1 spread. DOI:http://dx.doi.org/10.7554/eLife.08150.001 Viruses such as HIV-1 replicate by invading and hijacking cells, forcing the cells to make new copies of the virus. These copies then leave the cell and continue the infection by invading and hijacking new cells. There are two ways that viruses may move between cells, which are known as ‘cell-free’ and ‘cell-to-cell’ infection. In cell-free infection, the virus is released into the fluid that surrounds cells and moves from there into the next cell. In cell-to-cell infection the virus instead moves directly between cells across regions where the two cells make contact. Previous research has suggested that cell-to-cell infection is important for the spread of HIV-1. However, it is not known how much the virus relies on this process, as it is technically challenging to perform experiments that prevent cell-free infection without also stopping cell-to-cell infection. Iwami, Takeuchi et al. have overcome this problem by combining experiments on laboratory-grown cells with a mathematical model that describes how the different infection methods affect the spread of HIV-1. This revealed that the viruses spread using cell-to-cell infection about 60% of the time, which agrees with results previously found by another group of researchers. Iwami, Takeuchi et al. also found that cell-to-cell infection increases how quickly viruses can infect new cells and replicate inside them, and improves the fitness of the viruses. The environment around cells in humans and other animals is different to that found around laboratory-grown cells, and so more research will be needed to check whether this difference affects which method of infection the virus uses. If the virus does spread in a similar way in the body, then blocking the cell-free method of infection would not greatly affect how well HIV-1 is able to infect new cells. It may instead be more effective to develop HIV treatments that prevent cell-to-cell infection by the virus. DOI:http://dx.doi.org/10.7554/eLife.08150.002
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Affiliation(s)
- Shingo Iwami
- Mathematical Biology Laboratory, Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.,PRESTO, Japan Science and Technology Agency, Saitama, Japan.,CREST, Japan Science and Technology Agency, Saitama, Japan
| | - Junko S Takeuchi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Shinji Nakaoka
- Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Fabrizio Mammano
- INSERM-Genetics and Ecology of viruses, Hospital Saint Louis, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - François Clavel
- INSERM-Genetics and Ecology of viruses, Hospital Saint Louis, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Hisashi Inaba
- Graduate School of Mathematical Sciences, University of Tokyo, Tokyo, Japan
| | - Tomoko Kobayashi
- Laboratory for Animal Health, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, Kanagawa, Japan
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Kazuyuki Aihara
- Institute of Industrial Science, University of Tokyo, Tokyo, Japan.,Graduate School of Information Science and Technology, University of Tokyo, Tokyo, Japan
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Kei Sato
- CREST, Japan Science and Technology Agency, Saitama, Japan.,Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
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34
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Zhang T, Meng X, Zhang T. Global Dynamics of a Virus Dynamical Model with Cell-to-Cell Transmission and Cure Rate. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2015; 2015:758362. [PMID: 26504489 PMCID: PMC4609528 DOI: 10.1155/2015/758362] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 06/30/2015] [Accepted: 07/07/2015] [Indexed: 01/12/2023]
Abstract
The cure effect of a virus model with both cell-to-cell transmission and cell-to-virus transmission is studied. By the method of next generation matrix, the basic reproduction number is obtained. The locally asymptotic stability of the virus-free equilibrium and the endemic equilibrium is considered by investigating the characteristic equation of the model. The globally asymptotic stability of the virus-free equilibrium is proved by constructing suitable Lyapunov function, and the sufficient condition for the globally asymptotic stability of the endemic equilibrium is obtained by constructing suitable Lyapunov function and using LaSalle invariance principal.
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Affiliation(s)
- Tongqian Zhang
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao 266590, China
- State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
| | - Xinzhu Meng
- College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao 266590, China
- State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
| | - Tonghua Zhang
- Department of Mathematics, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122, Australia
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35
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Galloway NLK, Doitsh G, Monroe KM, Yang Z, Muñoz-Arias I, Levy DN, Greene WC. Cell-to-Cell Transmission of HIV-1 Is Required to Trigger Pyroptotic Death of Lymphoid-Tissue-Derived CD4 T Cells. Cell Rep 2015; 12:1555-1563. [PMID: 26321639 PMCID: PMC4565731 DOI: 10.1016/j.celrep.2015.08.011] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 06/17/2015] [Accepted: 08/04/2015] [Indexed: 12/27/2022] Open
Abstract
The progressive depletion of CD4 T cells underlies clinical progression to AIDS in untreated HIV-infected subjects. Most dying CD4 T cells correspond to resting nonpermissive cells residing in lymphoid tissues. Death is due to an innate immune response against the incomplete cytosolic viral DNA intermediates accumulating in these cells. The viral DNA is detected by the IFI16 sensor, leading to inflammasome assembly, caspase-1 activation, and the induction of pyroptosis, a highly inflammatory form of programmed cell death. We now show that cell-to-cell transmission of HIV is obligatorily required for activation of this death pathway. Cell-free HIV-1 virions, even when added in large quantities, fail to activate pyroptosis. These findings underscore the infected CD4 T cells as the major killing units promoting progression to AIDS and highlight a previously unappreciated role for the virological synapse in HIV pathogenesis.
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Affiliation(s)
- Nicole LK Galloway
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
| | - Gilad Doitsh
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
| | - Kathryn M. Monroe
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
| | - Zhiyuan Yang
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
| | - Isa Muñoz-Arias
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
| | - David N Levy
- Department of Basic Sciences and Craniofacial Biology, New York
University College of Dentistry, New York, NY, USA
| | - Warner C. Greene
- Gladstone Institute of Virology and Immunology, 1650 Owens Street,
San Francisco, CA 94158
- Department of Medicine, University of California, San Francisco, San
Francisco, CA 94143
- Department of Microbiology and Immunology, University of California,
San Francisco, San Francisco, CA 94143
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36
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Vpu Protein: The Viroporin Encoded by HIV-1. Viruses 2015; 7:4352-68. [PMID: 26247957 PMCID: PMC4576185 DOI: 10.3390/v7082824] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 06/29/2015] [Accepted: 07/28/2015] [Indexed: 02/06/2023] Open
Abstract
Viral protein U (Vpu) is a lentiviral viroporin encoded by human immunodeficiency virus type 1 (HIV-1) and some simian immunodeficiency virus (SIV) strains. This small protein of 81 amino acids contains a single transmembrane domain that allows for supramolecular organization via homoligomerization or interaction with other proteins. The topology and trafficking of Vpu through subcellular compartments result in pleiotropic effects in host cells. Notwithstanding the high variability of its amino acid sequence, the functionality of Vpu is well conserved in pandemic virus isolates. This review outlines our current knowledge on the interactions of Vpu with the host cell. The regulation of cellular physiology by Vpu and the validity of this viroporin as a therapeutic target are also discussed.
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37
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Shimura K, Miyazato P, Oishi S, Fujii N, Matsuoka M. Impact of HIV-1 infection pathways on susceptibility to antiviral drugs and on virus spread. Virology 2015; 484:364-376. [PMID: 26186575 DOI: 10.1016/j.virol.2015.06.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 06/08/2015] [Accepted: 06/26/2015] [Indexed: 11/19/2022]
Abstract
The infection routes of HIV-1 can affect several viral properties, including dissemination, pathogenesis, and immune evasion. In this study, we evaluated the inhibitory activity of a wide variety of anti-HIV drugs, focusing on the impact that different infection pathways have on their efficacy. Compared to cell-free infection, inhibitory activities were reduced in cell-to-cell productive transmission for all drugs tested. We detected weak reporter-expressing target cells after cell-to-cell transmission in the presence of integrase strand transfer inhibitors (INSTIs). Further analysis revealed that this expression was mainly due to unintegrated circular HIV (cHIV) DNAs, consisting of 1-LTR and 2-LTR circles. When in vitro-constructed cHIV DNAs were introduced into cells, the production of infectious and intercellular transmittable virions was observed, suggesting that cHIV DNA could be a source of infectious virus. These results highlight some advantages of the cell-to-cell infection mode for viral expansion, particularly in the presence of anti-retroviral drugs.
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Affiliation(s)
- Kazuya Shimura
- Institute for Virus Research, Kyoto University, Kyoto, Japan.
| | - Paola Miyazato
- Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Shinya Oishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Nobutaka Fujii
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Masao Matsuoka
- Institute for Virus Research, Kyoto University, Kyoto, Japan
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38
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Graw F, Martin DN, Perelson AS, Uprichard SL, Dahari H. Quantification of Hepatitis C Virus Cell-to-Cell Spread Using a Stochastic Modeling Approach. J Virol 2015; 89:6551-61. [PMID: 25833046 PMCID: PMC4468510 DOI: 10.1128/jvi.00016-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/24/2015] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED It has been proposed that viral cell-to-cell transmission plays a role in establishing and maintaining chronic infections. Thus, understanding the mechanisms and kinetics of cell-to-cell spread is fundamental to elucidating the dynamics of infection and may provide insight into factors that determine chronicity. Because hepatitis C virus (HCV) spreads from cell to cell and has a chronicity rate of up to 80% in exposed individuals, we examined the dynamics of HCV cell-to-cell spread in vitro and quantified the effect of inhibiting individual host factors. Using a multidisciplinary approach, we performed HCV spread assays and assessed the appropriateness of different stochastic models for describing HCV focus expansion. To evaluate the effect of blocking specific host cell factors on HCV cell-to-cell transmission, assays were performed in the presence of blocking antibodies and/or small-molecule inhibitors targeting different cellular HCV entry factors. In all experiments, HCV-positive cells were identified by immunohistochemical staining and the number of HCV-positive cells per focus was assessed to determine focus size. We found that HCV focus expansion can best be explained by mathematical models assuming focus size-dependent growth. Consistent with previous reports suggesting that some factors impact HCV cell-to-cell spread to different extents, modeling results estimate a hierarchy of efficacies for blocking HCV cell-to-cell spread when targeting different host factors (e.g., CLDN1 > NPC1L1 > TfR1). This approach can be adapted to describe focus expansion dynamics under a variety of experimental conditions as a means to quantify cell-to-cell transmission and assess the impact of cellular factors, viral factors, and antivirals. IMPORTANCE The ability of viruses to efficiently spread by direct cell-to-cell transmission is thought to play an important role in the establishment and maintenance of viral persistence. As such, elucidating the dynamics of cell-to-cell spread and quantifying the effect of blocking the factors involved has important implications for the design of potent antiviral strategies and controlling viral escape. Mathematical modeling has been widely used to understand HCV infection dynamics and treatment response; however, these models typically assume only cell-free virus infection mechanisms. Here, we used stochastic models describing focus expansion as a means to understand and quantify the dynamics of HCV cell-to-cell spread in vitro and determined the degree to which cell-to-cell spread is reduced when individual HCV entry factors are blocked. The results demonstrate the ability of this approach to recapitulate and quantify cell-to-cell transmission, as well as the impact of specific factors and potential antivirals.
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Affiliation(s)
- Frederik Graw
- Center for Modeling and Simulation in the Biosciences, BioQuant Center, Heidelberg University, Heidelberg, Germany
| | - Danyelle N Martin
- Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Loyola University Medical Center, Maywood, Illinois, USA
| | - Alan S Perelson
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Susan L Uprichard
- Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Loyola University Medical Center, Maywood, Illinois, USA Department of Microbiology and Immunology, Loyola University Medical Center, Maywood, Illinois, USA
| | - Harel Dahari
- Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Loyola University Medical Center, Maywood, Illinois, USA Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
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39
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MIV-150/zinc acetate gel inhibits cell-associated simian-human immunodeficiency virus reverse transcriptase infection in a macaque vaginal explant model. Antimicrob Agents Chemother 2015; 59:3829-37. [PMID: 25870063 DOI: 10.1128/aac.00073-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/07/2015] [Indexed: 12/22/2022] Open
Abstract
The transmission of both cell-free and cell-associated immunodeficiency viruses has been demonstrated directly in multiple animal species and possibly occurs in humans, as suggested by genotyping of the infecting human immunodeficiency virus (HIV) in acutely infected women and in semen from their partners. Therefore, a microbicide may need to block both mechanisms of HIV transmission to achieve maximum efficacy. To date, most of the preclinical evaluation of candidate microbicides has been performed using cell-free HIV. New models of mucosal transmission of cell-associated HIV are needed to evaluate candidate microbicide performance. The MIV-150/zinc acetate/carrageenan (MZC) gel protects Depo-Provera-treated macaques against cell-free simian-human immunodeficiency virus reverse transcriptase (SHIV-RT) infection when applied vaginally up to 8 h before challenge. We recently demonstrated the potent activity of MZC gel against cell-free SHIV-RT in macaque vaginal explants. In the current study, we established a cell-associated SHIV-RT infection model of macaque vaginal tissues and tested the activity of MZC gel in this model. MZC gel protected tissues against cell-associated SHIV-RT infection when present at the time of viral exposure or when applied up to 4 days prior to viral challenge. These data support clinical testing of the MZC gel. Overall, our ex vivo model of cell-associated SHIV-RT infection in macaque vaginal mucosa complements the cell-free infection models, providing tools for prioritization of products that block both modes of HIV transmission.
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40
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Madison MN, Jones PH, Okeoma CM. Exosomes in human semen restrict HIV-1 transmission by vaginal cells and block intravaginal replication of LP-BM5 murine AIDS virus complex. Virology 2015; 482:189-201. [PMID: 25880110 DOI: 10.1016/j.virol.2015.03.040] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/20/2015] [Accepted: 03/23/2015] [Indexed: 11/17/2022]
Abstract
Exosomes are membranous extracellular nanovesicles secreted by diverse cell types. Exosomes from healthy human semen have been shown to inhibit HIV-1 replication and to impair progeny virus infectivity. In this study, we examined the ability of healthy human semen exosomes to restrict HIV-1 and LP-BM5 murine AIDS virus transmission in three different model systems. We show that vaginal cells internalize exosomes with concomitant transfer of functional mRNA. Semen exosomes blocked the spread of HIV-1 from vaginal epithelial cells to target cells in our cell-to-cell infection model and suppressed transmission of HIV-1 across the vaginal epithelial barrier in our trans-well model. Our in vivo model shows that human semen exosomes restrict intravaginal transmission and propagation of murine AIDS virus. Our study highlights an antiretroviral role for semen exosomes that may be harnessed for the development of novel therapeutic strategies to combat HIV-1 transmission.
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Affiliation(s)
- Marisa N Madison
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Philip H Jones
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Chioma M Okeoma
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA; Interdisciplinary Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA 52242, USA.
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Showa SP, Nyabadza F, Hove-Musekwa SD, Magombedze G. A comparison of elasticities of viral levels to specific immune response mechanisms in human immunodeficiency virus infection. BMC Res Notes 2014; 7:737. [PMID: 25331717 PMCID: PMC4221687 DOI: 10.1186/1756-0500-7-737] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 10/02/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The presence of an asymptomatic phase in an HIV infection indicates that the immune system can partially control the infection. Determining the immune mechanisms that contribute significantly to the partial control of the infection enhance the HIV infection intervention strategies and is important in vaccine development. Towards this goal, a discrete time HIV model, which incorporates the life cycle aspects of the virus, the antibody (humoral) response and the cell-mediated immune response is formulated to determine immune system components that are most efficient in controlling viral levels. Ecological relationships are used to model the interplay between the immune system components and the HIV pathogen. Model simulations and transient elasticity analysis of the viral levels to immune response parameters are used to compare the different immune mechanisms. RESULTS It is shown that cell-mediated immune response is more effective in controlling the viral levels than the antibody response. Killing of infected cells is shown to be crucial in controlling the viral levels. Our results show a negative correlation between the antibody response and the viral levels in the early stages of the infection, but we predicted this immune mechanism to be positively correlated with the viral levels in the late stage of the infection. A result that suggests lack of relevance of antibody response with infection progression. On the contrary, we predicted the cell-mediated immune response to be always negatively correlated with viral levels. CONCLUSION Neutralizing antibodies can only control the viral levels in the early days of the HIV infection whereas cell-mediated immune response is beneficial during all the stages of the infection. This study predicts that vaccine design efforts should also focus on stimulating killer T cells that target infected cells.
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Affiliation(s)
- Sarudzai P Showa
- Department of Applied Mathematics, National University of Science and Technology, P,O, Box AC 939 Ascot, Bulawayo, Zimbabwe.
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Quan Y, Xu H, Kramer VG, Han Y, Sloan RD, Wainberg MA. Identification of an env-defective HIV-1 mutant capable of spontaneous reversion to a wild-type phenotype in certain T-cell lines. Virol J 2014; 11:177. [PMID: 25287969 PMCID: PMC4283149 DOI: 10.1186/1743-422x-11-177] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 09/26/2014] [Indexed: 04/08/2023] Open
Abstract
Background Attempts to eradicate HIV from cellular reservoirs are vital but depend on a clear understanding of how viral variants are transmitted and survive in the different cell types that constitute such reservoirs. Mutations in the env gene of HIV may be able to exert a differential influence on viral transmission ability in regard to cell-free and cell-associated viral forms. Methods The ability of HIV containing an env G367R mutation in cell-free and cell-associated viruses to cause infection and to revert to wild-type was measured using several T cell lines. To determine factors that might potentially influence the reversion of G367R, we studied each of entry inhibitors, inhibitors of cellular endocytosis, and modulators of cell growth and activation. Results We demonstrate that an HIV-1 variant containing a G367R substitution within the CD4 binding site of gp120 was non-infectious as free virus in culture but was infectious when infected cells were co-cultured with certain T cell lines or when cells were transfected by a relevant proviral plasmid. Differences in viral infectivity by cell-associated G367R viruses were determined by the type of target cell employed, regardless which type of donor cell was used. Reversion was slowed or inhibited by entry inhibitors and by inhibitors of cellular endocytosis. Interleukin 2 was able to block G367R reversion in only one of the T cell lines studied but not in the other, while phorbol 12-myristate 13-acetate (PMA) inhibited G367R reversion in all the T cell lines. Conclusions Env-defective HIV may have a different phenotype as cell-free versus cell-associated virus. The persistence of defective forms can potentially lead to the emergence of virulent forms. The heterogeneity of cell types that constitute the HIV reservoir can contribute to viral variability, even among similar types of cells. This is the first demonstration of a mutation in the HIV envelope, i.e. G367R, that can compromise infection by cell-free virus but less severely by cell-associated virus and that does so in a cell type-dependent manner.
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Affiliation(s)
| | | | | | | | | | - Mark A Wainberg
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Cote Sainte Catherine, Montreal, QC H3T 1E2, Canada.
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Distinct mechanisms regulate exposure of neutralizing epitopes in the V2 and V3 loops of HIV-1 envelope. J Virol 2014; 88:12853-65. [PMID: 25165106 DOI: 10.1128/jvi.02125-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Broadly neutralizing antibodies targeting the HIV-1 envelope (Env) are key components for protection against HIV-1. However, many cross-reactive epitopes are often occluded. This study investigates the mechanisms contributing to the masking of V2i (variable loop V2 integrin) epitopes compared to the accessibility of V3 epitopes. V2i are conformation-dependent epitopes encompassing the integrin α4β7-binding motif on the V1V2 loop of HIV-1 Env gp120. The V2i monoclonal antibodies (MAbs) display extensive cross-reactivity with gp120 monomers from many subtypes but neutralize only few viruses, indicating V2i's cryptic nature. First, we asked whether CD4-induced Env conformational changes affect V2i epitopes similarly to V3. CD4 treatment of BaL and JRFL pseudoviruses increased their neutralization sensitivity to V3 MAbs but not to the V2i MAbs. Second, the contribution of N-glycans in masking V2i versus V3 epitopes was evaluated by testing the neutralization of pseudoviruses produced in the presence of a glycosidase inhibitor, kifunensine. Viruses grown in kifunensine were more sensitive to neutralization by V3 but not V2i MAbs. Finally, we evaluated the time-dependent dynamics of the V2i and V3 epitopes. Extending the time of virus-MAb interaction to 18 h before adding target cells increased virus neutralization by some V2i MAbs and all V3 MAbs tested. Consistent with this, V2i MAb binding to Env on the surface of transfected cells also increased in a time-dependent manner. Hence, V2i and V3 epitopes are highly dynamic, but distinct factors modulate the antibody accessibility of these epitopes. The study reveals the importance of the structural dynamics of V2i and V3 epitopes in determining HIV-1 neutralization by antibodies targeting these sites. IMPORTANCE Conserved neutralizing epitopes are present in the V1V2 and V3 regions of HIV-1 Env, but these epitopes are often occluded from Abs. This study reveals that distinct mechanisms contribute to the masking of V3 epitopes and V2i epitopes in the V1V2 domain. Importantly, V3 MAbs and some V2i MAbs display greater neutralization against relatively resistant HIV-1 isolates when the MAbs interact with the virus for a prolonged period of time. Given their highly immunogenic nature, V3 and V2i epitopes are valuable targets that would augment the efficacy of HIV vaccines.
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HIV-1 Tat protein induces viral internalization through Env-mediated interactions in dose-dependent manner. AIDS 2013; 27:2355-64. [PMID: 23842123 DOI: 10.1097/01.aids.0000432452.83604.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To study the dose-dependent manner of HIV-1 Tat-induced effects on viral replication, internalization and spread, and to directly observe these effects on soluble Env immunogens and virus-like particles. DESIGN In order to determine the manner through which Tat affects viral replication, we incubated cells, virions and soluble Env spikes with Tat at different concentrations, and directly visualized the effects of such incubation. METHODS Cell-based infectivity assays were carried out to assay Tat dose-dependency of viral infectivity. Transmission electron microscopy of virus-like particles and soluble gp140 immunogens incubated with Tat at various concentrations was performed to directly observe Tat-induced effects. RESULTS Treating virus with exogenous Tat increased infectivity in a dose-dependent manner. In the presence of anti-Tat antibodies, virus replication and spread were repressed, postulating Tat contributions to disease progression. When CXCR4 coreceptors were blocked, Tat treatment overcame the inhibition relative to absence of Tat treatment. Similarly, syncytium formation between chronically infected and uninfected target cells was also increased by exogenous Tat treatment. Inhibiting the CD4 receptor for virus entry abolished syncytium formation and Tat treatment was unable to overcome CD4 dependency. We show that Tat reduces virus infectivity at higher Tat concentrations through Env interactions resulting in viral aggregation. CONCLUSION Treating virions or chronically infected cells with exogenous Tat could enhance virus infectivity and spread through coreceptor tropism switch or through another undetermined mechanism. The aggregation potential of Tat suggests a mechanism of negative-feedback regulation of viral replication, providing another regulative function to control viral replication.
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Skinner AM, Chakkaramakkil Verghese S, Kurre P. Cell-cell transmission of VSV-G pseudotyped lentivector particles. PLoS One 2013; 8:e74925. [PMID: 24040363 PMCID: PMC3769293 DOI: 10.1371/journal.pone.0074925] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 08/07/2013] [Indexed: 12/22/2022] Open
Abstract
Many replicating viruses, including HIV-1 and HTLV-1, are efficiently transmitted from the cell surface of actively infected cells upon contact with bystander cells. In a previous study, we reported the prolonged cell surface retention of VSV-G replication-deficient pseudotyped lentivector prior to endocytic entry. However, the competing kinetics of cell surface versus dissociation, neutralization or direct transfer to other cells have received comparatively little attention. Here we demonstrate that the relative efficiency of cell-cell surface transmission can outpace "cell-free" transduction at limiting vector input. This coincides with the prolonged half-life of cell bound vector but occurs, unlike HTLV-1, without evidence for particle aggregation. These studies suggest that cell-surface attachment stabilizes particles and alters neutralization kinetics. Our experiments provide novel insight into the underexplored cell-cell transmission of pseudotyped particles.
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Affiliation(s)
- Amy M. Skinner
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Santhosh Chakkaramakkil Verghese
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Peter Kurre
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon, United States of America
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Russell RA, Martin N, Mitar I, Jones E, Sattentau QJ. Multiple proviral integration events after virological synapse-mediated HIV-1 spread. Virology 2013; 443:143-9. [DOI: 10.1016/j.virol.2013.05.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/21/2013] [Accepted: 05/03/2013] [Indexed: 11/25/2022]
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Clustering and mobility of HIV-1 Env at viral assembly sites predict its propensity to induce cell-cell fusion. J Virol 2013; 87:7516-25. [PMID: 23637402 DOI: 10.1128/jvi.00790-13] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
HIV-1 Env mediates virus attachment to and fusion with target cell membranes, and yet, while Env is still situated at the plasma membrane of the producer cell and before its incorporation into newly formed particles, Env already interacts with the viral receptor CD4 on target cells, thus enabling the formation of transient cell contacts that facilitate the transmission of viral particles. During this first encounter with the receptor, Env must not induce membrane fusion, as this would prevent the producer cell and the target cell from separating upon virus transmission, but how Env's fusion activity is controlled remains unclear. To gain a better understanding of the Env regulation that precedes viral transmission, we examined the nanoscale organization of Env at the surface of producer cells. Utilizing superresolution microscopy (stochastic optical reconstruction microscopy [STORM]) and fluorescence recovery after photobleaching (FRAP), we quantitatively assessed the clustering and dynamics of Env upon its arrival at the plasma membrane. We found that Gag assembly induced the aggregation of small Env clusters into larger domains and that these domains were completely immobile. Truncation of the cytoplasmic tail (CT) of Env abrogated Gag's ability to induce Env clustering and restored Env mobility at assembly sites, both of which correlated with increased Env-induced fusion of infected and uninfected cells. Hence, while Env trapping by Gag secures Env incorporation into viral particles, Env clustering and its sequestration at assembly sites likely also leads to the repression of its fusion function, and thus, by preventing the formation of syncytia, Gag helps to secure efficient transfer of viral particles to target cells.
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Abstract
Human immunodeficiency virus type 1 is the cause of a modern global pandemic associated with progressive acquired immune deficiency. The infection is characterized by the loss of the primary target of viral infection, the CD4+ T cell. The measurement of plasma viremia in patients can predict the rate of CD4+ cell decline; however, it is not clear whether this cell-free plasma virus represents the engine that drives viral spread. Active viral replication is mainly observed within lymphoid tissues that are hotbeds of cell-cell interactions that initiate and organize immune responses. It is well established that cell-cell interactions enhance viral spread in vitro. Dendritic cell-T cell interactions, which lie at the heart of adaptive immune responses, enhance viral infection in vitro. Interactions between infected and uninfected CD4+ T cells are a dominant route of viral spread in vitro and are likely to play a central role in viral dissemination in vivo. Future studies will test existing paradigms of HIV-1 dissemination to determine whether virus-transmitting contacts between infected and uninfected T cells called virological synapses are the dominant mode of viral spread in vivo. Here, we review the status of our understanding of this mode of infection with a focus on T cell-T cell interactions and examine how it may explain resistance to neutralizing antibodies and or the generation of genetic diversity of HIV.
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Affiliation(s)
- Benjamin K Chen
- Division of Infectious Disease, Department of Medicine, Immunology Institute, Mount Sinai School of Medicine, One Gustave Levy Place, Box 1630, New York, NY 10029, USA.
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Schweitzer CJ, Jagadish T, Haverland N, Ciborowski P, Belshan M. Proteomic analysis of early HIV-1 nucleoprotein complexes. J Proteome Res 2013; 12:559-72. [PMID: 23282062 PMCID: PMC3564510 DOI: 10.1021/pr300869h] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
After entry into the cell, the early steps of the human immunodeficiency virus type 1 (HIV-1) replication cycle are mediated by two functionally distinct nucleoprotein complexes, the reverse transcription complex (RTC) and preintegration complex (PIC). These two unique viral complexes are responsible for the conversion of the single-stranded RNA genome into double-stranded DNA, transport of the DNA into the nucleus, and integration of the viral DNA into the host cell chromosome. Prior biochemical analyses suggest that these complexes are large and contain multiple undiscovered host cell factors. In this study, functional HIV-1 RTCs and PICs were partially purified by velocity gradient centrifugation and fractionation, concentrated, trypsin digested, and analyzed by LC-MS/MS. A total of seven parallel infected and control biological replicates were completed. Database searches were performed with Proteome Discoverer and a comparison of the HIV-1 samples to parallel uninfected control samples was used to identify unique cellular factors. The analysis produced a total data set of 11055 proteins. Several previously characterized HIV-1 factors were identified, including XRCC6, TFRC, and HSP70. The presence of XRCC6 was confirmed in infected fractions and shown to be associated with HIV-1 DNA by immunoprecipitation-PCR experiments. Overall, the analysis identified 94 proteins unique in the infected fractions and 121 proteins unique to the control fractions with ≥ 2 protein assignments. An additional 54 and 52 were classified as enriched in the infected and control samples, respectively, based on a 3-fold difference in total Proteome Discoverer probability score. The differential expression of several candidate proteins was validated by Western blot analysis. This study contributes additional novel candidate proteins to the growing published bioinformatic data sets of proteins that contribute to HIV-1 replication.
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MESH Headings
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Nuclear/genetics
- Antigens, Nuclear/metabolism
- Cell Line
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Cell Nucleus/virology
- Centrifugation, Density Gradient
- Chromatography, Liquid
- DNA, Viral/genetics
- DNA, Viral/metabolism
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Gene Expression Profiling
- HIV-1/genetics
- HIV-1/metabolism
- HSP70 Heat-Shock Proteins/genetics
- HSP70 Heat-Shock Proteins/metabolism
- Host-Pathogen Interactions
- Humans
- Ku Autoantigen
- Lymphocytes/metabolism
- Lymphocytes/virology
- Nucleoproteins/genetics
- Nucleoproteins/metabolism
- Protein Binding
- Proteome/genetics
- Proteome/metabolism
- Receptors, Transferrin/genetics
- Receptors, Transferrin/metabolism
- Reverse Transcription
- Tandem Mass Spectrometry
- Viral Proteins/genetics
- Viral Proteins/metabolism
- Virus Integration
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Affiliation(s)
| | - Teena Jagadish
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Nicole Haverland
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Pawel Ciborowski
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
- The Nebraska Center for Virology, University of Nebraska, Lincoln, NE
| | - Michael Belshan
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE
- The Nebraska Center for Virology, University of Nebraska, Lincoln, NE
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Spatial Aspects of HIV Infection. LECTURE NOTES ON MATHEMATICAL MODELLING IN THE LIFE SCIENCES 2013. [DOI: 10.1007/978-1-4614-4178-6_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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