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Diaz J, Sears J, Chang CK, Burdick J, Law I, Sanders W, Linnertz C, Sylvester P, Moorman N, Ferris MT, Heise MT. U-CAN-seq: A Universal Competition Assay by Nanopore Sequencing. Viruses 2024; 16:636. [PMID: 38675976 PMCID: PMC11054411 DOI: 10.3390/v16040636] [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: 02/29/2024] [Revised: 04/09/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
RNA viruses quickly evolve subtle genotypic changes that can have major impacts on viral fitness and host range, with potential consequences for human health. It is therefore important to understand the evolutionary fitness of novel viral variants relative to well-studied genotypes of epidemic viruses. Competition assays are an effective and rigorous system with which to assess the relative fitness of viral genotypes. However, it is challenging to quickly and cheaply distinguish and quantify fitness differences between very similar viral genotypes. Here, we describe a protocol for using reverse transcription PCR in combination with commercial nanopore sequencing services to perform competition assays on untagged RNA viruses. Our assay, called the Universal Competition Assay by Nanopore Sequencing (U-CAN-seq), is relatively cheap and highly sensitive. We used a well-studied N24A mutation in the chikungunya virus (CHIKV) nsp3 gene to confirm that we could detect a competitive disadvantage using U-CAN-seq. We also used this approach to show that mutations to the CHIKV 5' conserved sequence element that disrupt sequence but not structure did not affect the fitness of CHIKV. However, similar mutations to an adjacent CHIKV stem loop (SL3) did cause a fitness disadvantage compared to wild-type CHIKV, suggesting that structure-independent, primary sequence determinants in this loop play an important role in CHIKV biology. Our novel findings illustrate the utility of the U-CAN-seq competition assay.
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Affiliation(s)
- Jennifer Diaz
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
| | - John Sears
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
| | - Che-Kang Chang
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
| | - Jane Burdick
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Isabella Law
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Wes Sanders
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
| | - Colton Linnertz
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Paul Sylvester
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Nathaniel Moorman
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
- The Rapidly Emerging Antiviral Drug Development Initiative (READDI), Chapel Hill, NC 275114, USA
| | - Martin T. Ferris
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Mark T. Heise
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; (J.D.)
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
- The Rapidly Emerging Antiviral Drug Development Initiative (READDI), Chapel Hill, NC 275114, USA
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Koutsoudakis G, Paris de León A, Herrera C, Dorner M, Pérez-Vilaró G, Lyonnais S, Grijalvo S, Eritja R, Meyerhans A, Mirambeau G, Díez J. Oligonucleotide-Lipid Conjugates Forming G-Quadruplex Structures Are Potent and Pangenotypic Hepatitis C Virus Entry Inhibitors In Vitro and Ex Vivo. Antimicrob Agents Chemother 2017; 61:e02354-16. [PMID: 28193659 PMCID: PMC5404530 DOI: 10.1128/aac.02354-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 02/07/2017] [Indexed: 12/14/2022] Open
Abstract
A hepatitis C virus (HCV) epidemic affecting HIV-infected men who have sex with men (MSM) is expanding worldwide. In spite of the improved cure rates obtained with the new direct-acting antiviral drug (DAA) combinations, the high rate of reinfection within this population calls urgently for novel preventive interventions. In this study, we determined in cell culture and ex vivo experiments with human colorectal tissue that lipoquads, G-quadruplex DNA structures fused to cholesterol, are efficient HCV pangenotypic entry and cell-to-cell transmission inhibitors. Thus, lipoquads may be promising candidates for the development of rectally applied gels to prevent HCV transmission.
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Affiliation(s)
- George Koutsoudakis
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Alexia Paris de León
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Carolina Herrera
- Section of Virology, Faculty of Medicine, St. Mary's Campus, Imperial College London, London, United Kingdom
| | - Marcus Dorner
- Section of Virology, Faculty of Medicine, St. Mary's Campus, Imperial College London, London, United Kingdom
| | - Gemma Pérez-Vilaró
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Sébastien Lyonnais
- AIDS Research Group, Institut D'Investigacions Biomèdics August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Santiago Grijalvo
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) and Networking Centre on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Ramon Eritja
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC) and Networking Centre on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Andreas Meyerhans
- Infection Biology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
- ICREA, Barcelona, Spain
| | - Gilles Mirambeau
- AIDS Research Group, Institut D'Investigacions Biomèdics August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Faculté de Biologie, Sorbonne Universités, UPMC Université Paris 06, Paris, France
| | - Juana Díez
- Molecular Virology Group, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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Beauparlant D, Rusert P, Magnus C, Kadelka C, Weber J, Uhr T, Zagordi O, Oberle C, Duenas-Decamp MJ, Clapham PR, Metzner KJ, Günthard HF, Trkola A. Delineating CD4 dependency of HIV-1: Adaptation to infect low level CD4 expressing target cells widens cellular tropism but severely impacts on envelope functionality. PLoS Pathog 2017; 13:e1006255. [PMID: 28264054 PMCID: PMC5354460 DOI: 10.1371/journal.ppat.1006255] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/16/2017] [Accepted: 02/22/2017] [Indexed: 02/07/2023] Open
Abstract
A hallmark of HIV-1 infection is the continuously declining number of the virus' predominant target cells, activated CD4+ T cells. With diminishing CD4+ T cell levels, the capacity to utilize alternate cell types and receptors, including cells that express low CD4 receptor levels such as macrophages, thus becomes crucial. To explore evolutionary paths that allow HIV-1 to acquire a wider host cell range by infecting cells with lower CD4 levels, we dissected the evolution of the envelope-CD4 interaction under in vitro culture conditions that mimicked the decline of CD4high target cells, using a prototypic subtype B, R5-tropic strain. Adaptation to CD4low targets proved to severely alter envelope functions including trimer opening as indicated by a higher affinity to CD4 and loss in shielding against neutralizing antibodies. We observed a strikingly decreased infectivity on CD4high target cells, but sustained infectivity on CD4low targets, including macrophages. Intriguingly, the adaptation to CD4low targets altered the kinetic of the entry process, leading to rapid CD4 engagement and an extended transition time between CD4 and CCR5 binding during entry. This phenotype was also observed for certain central nervous system (CNS) derived macrophage-tropic viruses, highlighting that the functional perturbation we defined upon in vitro adaptation to CD4low targets occurs in vivo. Collectively, our findings suggest that CD4low adapted envelopes may exhibit severe deficiencies in entry fitness and shielding early in their evolution. Considering this, adaptation to CD4low targets may preferentially occur in a sheltered and immune-privileged environment such as the CNS to allow fitness restoring compensatory mutations to occur.
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Affiliation(s)
- David Beauparlant
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Peter Rusert
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Carsten Magnus
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Claus Kadelka
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
| | - Jacqueline Weber
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Therese Uhr
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Osvaldo Zagordi
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Corinna Oberle
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Maria J. Duenas-Decamp
- Program in Molecular Medicine, Biotech II, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Paul R. Clapham
- Program in Molecular Medicine, Biotech II, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Karin J. Metzner
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
| | - Huldrych F. Günthard
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
| | - Alexandra Trkola
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- * E-mail:
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4
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Godinho-Santos A, Hance AJ, Gonçalves J, Mammano F. CIB1 and CIB2 are HIV-1 helper factors involved in viral entry. Sci Rep 2016; 6:30927. [PMID: 27489023 PMCID: PMC4973253 DOI: 10.1038/srep30927] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 07/05/2016] [Indexed: 01/05/2023] Open
Abstract
HIV-1 relies on the host-cell machinery to accomplish its replication cycle, and characterization of these helper factors contributes to a better understanding of HIV-host interactions and can identify potential novel antiviral targets. Here we explored the contribution of CIB2, previously identified by RNAi screening as a potential helper factor, and its homolog, CIB1. Knockdown of either CIB1 or CIB2 strongly impaired viral replication in Jurkat cells and in primary CD4+ T-lymphocytes, identifying these proteins as non-redundant helper factors. Knockdown of CIB1 and CIB2 impaired envelope-mediated viral entry for both for X4- and R5-tropic HIV-1, and both cell-free and cell-associated entry pathways were affected. In contrast, the level of CIB1 and CIB2 expression did not influence cell viability, cell proliferation, receptor-independent viral binding to the cell surface, or later steps in the viral replication cycle. CIB1 and CIB2 knockdown was found to reduce the expression of surface molecules implicated in HIV-1 infection, including CXCR4, CCR5 and integrin α4β7, suggesting at least one mechanism through which these proteins promote viral infection. Thus, this study identifies CIB1 and CIB2 as host helper factors for HIV-1 replication that are required for optimal receptor-mediated viral entry.
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Affiliation(s)
- Ana Godinho-Santos
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.,INSERM, U941, Paris, F-75010, France
| | - Allan J Hance
- INSERM, U941, Paris, F-75010, France.,Univ Paris Diderot, Sorbonne Paris Cité, F-75475, Paris, France
| | - João Gonçalves
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Fabrizio Mammano
- INSERM, U941, Paris, F-75010, France.,Univ Paris Diderot, Sorbonne Paris Cité, F-75475, Paris, France
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Pan-genotypic Hepatitis C Virus Inhibition by Natural Products Derived from the Wild Egyptian Artichoke. J Virol 2015; 90:1918-30. [PMID: 26656684 DOI: 10.1128/jvi.02030-15] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/25/2015] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infection is the leading cause of chronic liver diseases. Water extracts of the leaves of the wild Egyptian artichoke (WEA) [Cynara cardunculus L. var. sylvestris (Lam.) Fiori] have been used for centuries in the Sinai Peninsula to treat hepatitis symptoms. Here we isolated and characterized six compounds from the water extracts of WEA and evaluated their HCV inhibition capacities in vitro. Importantly, two of these compounds, grosheimol and cynaropicrin, inhibited HCV with half-maximal effective concentrations (EC50s) in the low micromolar range. They inhibited HCV entry into target cells and were active against both cell-free infection as well as cell-cell transmission. Furthermore, the antiviral activity of both compounds was pan-genotypic as HCV genotypes 1a, 1b, 2b, 3a, 4a, 5a, 6a, and 7a were inhibited. Thus, grosheimol and cynaropicrin are promising candidates for the development of new pan-genotypic entry inhibitors of HCV infection. IMPORTANCE Because there is no preventive HCV vaccine available today, the discovery of novel anti-HCV cell entry inhibitors could help develop preventive measures against infection. The present study describes two compounds isolated from the wild Egyptian artichoke (WEA) with respect to their structural elucidation, absolute configuration, and quantitative determination. Importantly, both compounds inhibited HCV infection in vitro. The first compound was an unknown molecule, and it was designated "grosheimol," while the second compound is the known molecule cynaropicrin. Both compounds belong to the group of sesquiterpene lactones. The mode of action of these compounds occurred during the early steps of the HCV life cycle, including cell-free and cell-cell infection inhibition. These natural compounds present promising candidates for further development into anti-HCV therapeutics.
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Gordts SC, Férir G, D’huys T, Petrova MI, Lebeer S, Snoeck R, Andrei G, Schols D. The Low-Cost Compound Lignosulfonic Acid (LA) Exhibits Broad-Spectrum Anti-HIV and Anti-HSV Activity and Has Potential for Microbicidal Applications. PLoS One 2015; 10:e0131219. [PMID: 26132818 PMCID: PMC4488490 DOI: 10.1371/journal.pone.0131219] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 05/30/2015] [Indexed: 12/24/2022] Open
Abstract
Objectives Lignosulfonic acid (LA), a low-cost lignin-derived polyanionic macromolecule, was extensively studied for its anti-HIV and anti-HSV activity in various cellular assays, its mechanism of viral inhibition and safety profile as potential microbicide. Results LA demonstrated potent inhibitory activity of HIV replication against a wide range of R5 and X4 HIV strains and prevented the uptake of HIV by bystander CD4+ T cells from persistently infected T cells in vitro (IC50: 0.07 – 0.34 μM). LA also inhibited HSV-2 replication in vitro in different cell types (IC50: 0.42 – 1.1 μM) and in rodents in vivo. Furthermore, LA neutralized the HIV-1 and HSV-2 DC-SIGN-mediated viral transfer to CD4+ T cells (IC50: ∼1 μM). In addition, dual HIV-1/HSV-2 infection in T cells was potently blocked by LA (IC50: 0.71 μM). No antiviral activity was observed against the non-enveloped viruses Coxsackie type B4 and Reovirus type 1. LA is defined as a HIV entry inhibitor since it interfered with gp120 binding to the cell surface of T cells. Pretreatment of PBMCs with LA neither increased expression levels of cellular activation markers (CD69, CD25 and HLA-DR), nor enhanced HIV-1 replication. Furthermore, we found that LA had non-antagonistic effects with acyclovir, PRO2000 or LabyA1 (combination index (CI): 0.46 – 1.03) in its anti-HSV-2 activity and synergized with tenofovir (CI: 0.59) in its anti-HIV-1 activity. To identify mechanisms of LA resistance, we generated in vitro a mutant HIV-1 NL4.3LAresistant virus, which acquired seven mutations in the HIV-1 envelope glycoproteins: S160N, V170N, Q280H and R389T in gp120 and K77Q, N113D and H132Y in gp41. Additionally, HIV-1 NL4.3LAresistant virus showed cross-resistance with feglymycin, enfuvirtide, PRO2000 and mAb b12, four well-described HIV binding/fusion inhibitors. Importantly, LA did not affect the growth of vaginal Lactobacilli strains. Conclusion Overall, these data highlight LA as a potential and unique low-cost microbicide displaying broad anti-HIV and anti-HSV activity.
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Affiliation(s)
| | - Geoffrey Férir
- Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
- * E-mail:
| | - Thomas D’huys
- Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Mariya I. Petrova
- Centre of Microbial and Plant Genetics, University of Leuven, Leuven, Belgium
- Department of Bioscience Engineering, Antwerp University, Antwerp, Belgium
| | - Sarah Lebeer
- Centre of Microbial and Plant Genetics, University of Leuven, Leuven, Belgium
- Department of Bioscience Engineering, Antwerp University, Antwerp, Belgium
| | - Robert Snoeck
- Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Graciela Andrei
- Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Dominique Schols
- Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
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HIV-1 fitness cost associated with escape from the VRC01 class of CD4 binding site neutralizing antibodies. J Virol 2015; 89:4201-13. [PMID: 25631091 DOI: 10.1128/jvi.03608-14] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED Broadly neutralizing antibodies (bNAbs) have been isolated from selected HIV-1-infected individuals and shown to bind to conserved sites on the envelope glycoprotein (Env). However, circulating plasma virus in these donors is usually resistant to autologous isolated bNAbs, indicating that during chronic infection, HIV-1 can escape from even broadly cross-reactive antibodies. Here, we evaluate if such viral escape is associated with an impairment of viral replication. Antibodies of the VRC01 class target the functionally conserved CD4 binding site and share a structural mode of gp120 recognition that includes mimicry of the CD4 receptor. We examined naturally occurring VRC01-sensitive and -resistant viral strains, as well as their mutated sensitive or resistant variants, and tested point mutations in the backbone of the VRC01-sensitive isolate YU2. In several cases, VRC01 resistance was associated with a reduced efficiency of CD4-mediated viral entry and diminished viral replication. Several mutations, alone or in combination, in the loop D or β23-V5 region of Env conferred a high level of resistance to VRC01 class antibodies, suggesting a preferred escape pathway. We further mapped the VRC01-induced escape pathway in vivo using Envs from donor 45, from whom antibody VRC01 was isolated. Initial escape mutations, including the addition of a key glycan, occurred in loop D and were associated with impaired viral replication; however, compensatory mutations restored full replicative fitness. These data demonstrate that escape from VRC01 class antibodies can diminish viral replicative fitness, but compensatory changes may explain the limited impact of neutralizing antibodies during the course of natural HIV-1 infection. IMPORTANCE Some antibodies that arise during natural HIV-1 infection bind to conserved regions on the virus envelope glycoprotein and potently neutralize the majority of diverse HIV-1 strains. The VRC01 class of antibodies blocks the conserved CD4 receptor binding site interaction that is necessary for viral entry, raising the possibility that viral escape from antibody neutralization might exert detrimental effects on viral function. Here, we show that escape from VRC01 class antibodies can be associated with impaired viral entry and replication; however, during the course of natural infection, compensatory mutations restore the ability of the virus to replicate normally.
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8
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Enhanced fusion and virion incorporation for HIV-1 subtype C envelope glycoproteins with compact V1/V2 domains. J Virol 2013; 88:2083-94. [PMID: 24335304 DOI: 10.1128/jvi.02308-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In infected people, the HIV-1 envelope glycoprotein (Env) constantly evolves to escape the immune response while retaining the essential elements needed to mediate viral entry into target cells. The extensive genetic variation of Env is particularly striking in the V1/V2 hypervariable domains. In this study, we investigated the trade-off, in terms of fusion efficiency, for encoding V1/V2 domains of different lengths. We found that natural variations in V1/V2 length exert a profound impact on HIV-1 entry. Variants encoding compact V1/V2 domains mediated fusion with higher efficiencies than related Envs encoding longer V1/V2 domains. By exchanging the V1/V2 domains between Envs of the same infected person or between two persons linked by a transmission event, we further demonstrated that V1/V2 domains critically influence both Env incorporation into viral particles and fusion to primary CD4 T cells and monocyte-derived dendritic cells. Shortening the V1/V2 domains consistently increased Env incorporation and fusion, whereas lengthening the V1/V2 domains decreased Env incorporation and fusion. Given that in a new host transmitted founder viruses are distinguished by compact Envs with fewer glycosylation sites, our study points to fusion and possibly Env incorporation into virions as limiting steps for transmission of HIV-1 to a new host and suggests that the length and/or the N-glycosylation profile of the V1/V2 domain influences these early steps in the HIV life cycle.
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9
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Peters PJ, Richards K, Clapham P. Human immunodeficiency viruses: propagation, quantification, and storage. CURRENT PROTOCOLS IN MICROBIOLOGY 2013; Chapter 15:Unit 15J.1. [PMID: 23408133 DOI: 10.1002/9780471729259.mc15j01s28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Described in this unit are basic protocols frequently used in the research of human immunodeficiency viruses (HIVs). Provided are methods for propagating and quantifying HIV, as well as recommendations for long-term storage. Background information about these methods is also provided and includes their advantages, disadvantages, and troubleshooting.
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Affiliation(s)
- Paul J Peters
- Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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10
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Diskin R, Klein F, Horwitz JA, Halper-Stromberg A, Sather DN, Marcovecchio PM, Lee T, West AP, Gao H, Seaman MS, Stamatatos L, Nussenzweig MC, Bjorkman PJ. Restricting HIV-1 pathways for escape using rationally designed anti-HIV-1 antibodies. ACTA ACUST UNITED AC 2013; 210:1235-49. [PMID: 23712429 PMCID: PMC3674693 DOI: 10.1084/jem.20130221] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mutating anti–HIV-1 broadly neutralizing antibodies increases their breadth and reduces pathways for viral escape through mutation. Recently identified broadly neutralizing antibodies (bNAbs) that potently neutralize most HIV-1 strains are key to potential antibody-based therapeutic approaches to combat HIV/AIDS in the absence of an effective vaccine. Increasing bNAb potencies and resistance to common routes of HIV-1 escape through mutation would facilitate their use as therapeutics. We previously used structure-based design to create the bNAb NIH45-46G54W, which exhibits superior potency and/or breadth compared with other bNAbs. We report new, more effective NIH45-46G54W variants designed using analyses of the NIH45-46–gp120 complex structure and sequences of NIH45-46G54W–resistant HIV-1 strains. One variant, 45-46m2, neutralizes 96% of HIV-1 strains in a cross-clade panel and viruses isolated from an HIV-infected individual that are resistant to all other known bNAbs, making it the single most broad and potent anti–HIV-1 antibody to date. A description of its mechanism is presented based on a 45-46m2–gp120 crystal structure. A second variant, 45-46m7, designed to thwart HIV-1 resistance to NIH45-46G54W arising from mutations in a gp120 consensus sequence, targets a common route of HIV-1 escape. In combination, 45-46m2 and 45-46m7 reduce the possible routes for the evolution of fit viral escape mutants in HIV-1YU-2–infected humanized mice, with viremic control exhibited when a third antibody, 10–1074, was added to the combination.
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Affiliation(s)
- Ron Diskin
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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11
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Broadly neutralizing antibodies developed by an HIV-positive elite neutralizer exact a replication fitness cost on the contemporaneous virus. J Virol 2012; 86:12676-85. [PMID: 22973035 DOI: 10.1128/jvi.01893-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Approximately 1% of those infected with HIV-1 develop broad and potent serum cross-neutralizing antibody activities. It is unknown whether or not the development of such immune responses affects the replication of the contemporaneous autologous virus. Here, we defined a pathway of autologous viral escape from contemporaneous potent and broad serum neutralizing antibodies developed by an elite HIV-1-positive (HIV-1(+)) neutralizer. These antibodies potently neutralize diverse isolates from different clades and target primarily the CD4-binding site (CD4-BS) of the viral envelope glycoprotein. Viral escape required mutations in the viral envelope glycoprotein which limited the accessibility of the CD4-binding site to the autologous broadly neutralizing anti-CD4-BS antibodies but which allowed the virus to infect cells by utilizing CD4 receptors on their surface. The acquisition of neutralization resistance, however, resulted in reduced cell entry potential and slower viral replication kinetics. Our results indicate that in vivo escape from autologous broadly neutralizing antibodies exacts fitness costs to HIV-1.
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12
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Kishko M, Somasundaran M, Brewster F, Sullivan JL, Clapham PR, Luzuriaga K. Genotypic and functional properties of early infant HIV-1 envelopes. Retrovirology 2011; 8:67. [PMID: 21843318 PMCID: PMC3189118 DOI: 10.1186/1742-4690-8-67] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/15/2011] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Understanding the properties of HIV-1 variants that are transmitted from women to their infants is crucial to improving strategies to prevent transmission. In this study, 162 full-length envelope (env) clones were generated from plasma RNA obtained from 5 HIV-1 Clade B infected mother-infant pairs. Following extensive genotypic and phylogenetic analyses, 35 representative clones were selected for functional studies. RESULTS Infant quasispecies were highly homogeneous and generally represented minor maternal variants, consistent with transmission across a selective bottleneck. Infant clones did not differ from the maternal in env length, or glycosylation. All infant variants utilized the CCR5 co-receptor, but were not macrophage tropic. Relatively high levels (IC₅₀ ≥ 100 μg/ml) of autologous maternal plasma IgG were required to neutralize maternal and infant viruses; however, all infant viruses were neutralized by pooled sera from HIV-1 infected individuals, implying that they were not inherently neutralization-resistant. All infant viruses were sensitive to the HIV-1 entry inhibitors Enfuvirtide and soluble CD4; none were resistant to Maraviroc. Sensitivity to human monoclonal antibodies 4E10, 2F5, b12 and 2G12 varied. CONCLUSIONS This study provides extensive characterization of the genotypic and functional properties of HIV-1 env shortly after transmission. We present the first detailed comparisons of the macrophage tropism of infant and maternal env variants and their sensitivity to Maraviroc, the only CCR5 antagonist approved for therapeutic use. These findings may have implications for improving approaches to prevent mother-to-child HIV-1 transmission.
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Affiliation(s)
- Michael Kishko
- Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mohan Somasundaran
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | - Frank Brewster
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | - John L Sullivan
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Paul R Clapham
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Katherine Luzuriaga
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA
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13
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Martínez JP, Bocharov G, Ignatovich A, Reiter J, Dittmar MT, Wain-Hobson S, Meyerhans A. Fitness ranking of individual mutants drives patterns of epistatic interactions in HIV-1. PLoS One 2011; 6:e18375. [PMID: 21483787 PMCID: PMC3069090 DOI: 10.1371/journal.pone.0018375] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 02/28/2011] [Indexed: 11/19/2022] Open
Abstract
Fitness interactions between mutations, referred to as epistasis, can strongly impact evolution. For RNA viruses and retroviruses with their high mutation rates, epistasis may be particularly important to overcome fitness losses due to the accumulation of deleterious mutations and thus could influence the frequency of mutants in a viral population. As human immunodeficiency virus type 1 (HIV-1) resistance to azidothymidine (AZT) requires selection of sequential mutations, it is a good system to study the impact of epistasis. Here we present a thorough analysis of a classical AZT-resistance pathway (the 41–215 cluster) of HIV-1 variants by fitness measurements in single round infection assays covering physiological drug concentrations ex vivo. The sign and value of epistasis varied and did not predict the epistatic effect on the mutant frequency. This complex behavior is explained by the fitness ranking of the variants that strongly depends on environmental factors, i.e., the presence and absence of drugs and the host cells used. Although some interactions compensate fitness losses, the observed small effect on the relative mutant frequencies suggests that epistasis might be inefficient as a buffering mechanism for fitness losses in vivo. While the use of epistasis-based hypotheses to make general assumptions on the evolutionary dynamics of viral populations is appealing, our data caution their interpretation without further knowledge on the characteristics of the viral mutant spectrum under different environmental conditions.
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Affiliation(s)
| | - Gennady Bocharov
- Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russian Federation
| | - Anna Ignatovich
- Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russian Federation
| | - Jochen Reiter
- Department of Virology, University of the Saarland, Homburg, Germany
| | - Matthias T. Dittmar
- Centre for Immunology and Infectious Disease, Barts and The London School of Medicine and Dentistry, London, United Kingdom
| | | | - Andreas Meyerhans
- Department of Virology, University of the Saarland, Homburg, Germany
- ICREA Infection Biology Laboratory, Department of Experimental and Health Sciences, University Pompeu Fabra, Barcelona, Spain
- * E-mail:
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14
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Lynch RM, Rong R, Boliar S, Sethi A, Li B, Mulenga J, Allen S, Robinson JE, Gnanakaran S, Derdeyn CA. The B cell response is redundant and highly focused on V1V2 during early subtype C infection in a Zambian seroconverter. J Virol 2011; 85:905-15. [PMID: 20980495 PMCID: PMC3020014 DOI: 10.1128/jvi.02006-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 10/21/2010] [Indexed: 12/13/2022] Open
Abstract
High-titer autologous neutralizing antibody responses have been demonstrated during early subtype C human immunodeficiency virus type 1 (HIV-1) infection. However, characterization of this response against autologous virus at the monoclonal antibody (MAb) level has only recently begun to be elucidated. Here we describe five monoclonal antibodies derived from a subtype C-infected seroconverter and their neutralizing activities against pseudoviruses that carry envelope glycoproteins from 48 days (0 month), 2 months, and 8 months after the estimated time of infection. Sequence analysis indicated that the MAbs arose from three distinct B cell clones, and their pattern of neutralization compared to that in patient plasma suggested that they circulated between 2 and 8 months after infection. Neutralization by MAbs representative of each B cell clone was mapped to two residues: position 134 in V1 and position 189 in V2. Mutational analysis revealed cooperative effects between glycans and residues at these two positions, arguing that they contribute to a single epitope. Analysis of the cognate gp120 sequence through homology modeling places this potential epitope near the interface between the V1 and V2 loops. Additionally, the escape mutation R189S in V2, which conferred resistance against all three MAbs, had no detrimental effect on virus replication in vitro. Taken together, our data demonstrate that independent B cells repeatedly targeted a single structure in V1V2 during early infection. Despite this assault, a single amino acid change was sufficient to confer complete escape with minimal impact on replication fitness.
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Affiliation(s)
- Rebecca M Lynch
- Emory Vaccine Center, Emory University, 954 Gatewood Rd., Atlanta, GA 30329, USA
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15
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Herrmann M, Ruprecht K, Sauter M, Martinez J, van Heteren P, Glas M, Best B, Meyerhans A, Roemer K, Mueller-Lantzsch N. Interaction of human immunodeficiency virus gp120 with the voltage-gated potassium channel BEC1. FEBS Lett 2010; 584:3513-8. [DOI: 10.1016/j.febslet.2010.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 06/18/2010] [Accepted: 07/08/2010] [Indexed: 01/04/2023]
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16
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Cavrois M, Neidleman J, Galloway N, Derdeyn CA, Hunter E, Greene WC. Measuring HIV fusion mediated by envelopes from primary viral isolates. Methods 2010; 53:34-8. [PMID: 20554044 DOI: 10.1016/j.ymeth.2010.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 05/19/2010] [Accepted: 05/26/2010] [Indexed: 11/19/2022] Open
Abstract
Over the course of infection, the human immunodeficiency virus type 1 (HIV-1) continuously adapts in part to evade the host's neutralizing antibody response. Antibodies often target the HIV envelope proteins that mediate HIV fusion to its cellular targets. HIV virions pseudotyped with primary envelopes have often been used to explore the fusogenic properties of these envelopes. Unfortunately, these pseudotyped virions fuse with greatly reduced efficiency to primary cells. Here, we describe a relatively simple strategy to clone primary envelopes into a provirus and increase the sensitivity of the virion-based fusion assay.
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Affiliation(s)
- Marielle Cavrois
- Gladstone Institute of Virology and Immunology, San Francisco, CA 94158, USA.
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17
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Lynch RM, Rong R, Li B, Shen T, Honnen W, Mulenga J, Allen S, Pinter A, Gnanakaran S, Derdeyn CA. Subtype-specific conservation of isoleucine 309 in the envelope V3 domain is linked to immune evasion in subtype C HIV-1 infection. Virology 2010; 404:59-70. [PMID: 20494390 DOI: 10.1016/j.virol.2010.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 03/17/2010] [Accepted: 04/10/2010] [Indexed: 11/19/2022]
Abstract
The V3 region of the HIV-1 envelope (Env) glycoprotein gp120 is a key functional domain yet it exhibits distinct mutational patterns across subtypes. Here an invariant residue (Ile 309) was replaced with Leu in 7 subtype C patient-derived Envs from recent infection and 4 related neutralizing antibody escape variants that emerged later. For these 11 Envs, I309L did not alter replication in primary CD4 T cells; however, replication in monocyte-derived macrophages was enhanced. Infection of cell lines with low CD4 or CCR5 revealed that I309L enhanced utilization of CD4 but did not affect the ability to use CCR5. This CD4-enhanced phenotype tracked with sensitivity to sCD4, indicating increased exposure of the CD4 binding site. The results suggest that Ile 309 preserves a V3-mediated masking function that occludes the CD4 binding site. The findings point to an immune evasion strategy in subtype C Env to protect this vulnerable immune target.
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Affiliation(s)
- Rebecca M Lynch
- Immunology and Molecular Pathogenesis Program, Emory University, Atlanta, GA 30329, USA
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18
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A novel, rapid method to detect infectious HIV-1 from plasma of persons infected with HIV-1. J Virol Methods 2010; 165:90-6. [DOI: 10.1016/j.jviromet.2010.01.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 01/19/2010] [Accepted: 01/21/2010] [Indexed: 12/21/2022]
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19
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Enhancement of the influenza A hemagglutinin (HA)-mediated cell-cell fusion and virus entry by the viral neuraminidase (NA). PLoS One 2009; 4:e8495. [PMID: 20041119 PMCID: PMC2795206 DOI: 10.1371/journal.pone.0008495] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 11/19/2009] [Indexed: 11/19/2022] Open
Abstract
Background The major role of the neuraminidase (NA) protein of influenza A virus is related to its sialidase activity, which disrupts the interaction between the envelope hemagglutin (HA) protein and the sialic acid receptors expressed at the surface of infected cells. This enzymatic activity is known to promote the release and spread of progeny viral particles following their production by infected cells, but a potential role of NA in earlier steps of the viral life cycle has never been clearly demonstrated. In this study we have examined the impact of NA expression on influenza HA-mediated viral membrane fusion and virion infectivity. Methodology/Principal Findings The role of NA in the early stages of influenza virus replication was examined using a cell-cell fusion assay that mimics HA-mediated membrane fusion, and a virion infectivity assay using HIV-based pseudoparticles expressing influenza HA and/or NA proteins. In the cell-cell fusion assay, which bypasses the endocytocytosis step that is characteristic of influenza virus entry, we found that in proper HA maturation conditions, NA clearly enhanced fusion in a dose-dependent manner. Similarly, expression of NA at the surface of pseudoparticles significantly enhanced virion infectivity. Further experiments using exogeneous soluble NA revealed that the most likely mechanism for enhancement of fusion and infectivity by NA was related to desialylation of virion-expressed HA. Conclusion/Significance The NA protein of influenza A virus is not only required for virion release and spread but also plays a critical role in virion infectivity and HA-mediated membrane fusion.
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Geuenich S, Kaderali L, Allespach I, Sertel S, Keppler OT. Biological signature characteristics of primary isolates from human immunodeficiency virus type 1 group O in ex vivo human tonsil histocultures. J Virol 2009; 83:10494-503. [PMID: 19706709 PMCID: PMC2753123 DOI: 10.1128/jvi.00928-09] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Accepted: 07/30/2009] [Indexed: 01/09/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) group M viruses have achieved a global distribution, while HIV-1 group O viruses are endemic only in particular regions of Africa. Here, we evaluated biological characteristics of group O and group M viruses in ex vivo models of HIV-1 infection. The replicative capacity and ability to induce CD4 T-cell depletion of eight group O and seven group M primary isolates were monitored in cultures of human peripheral blood mononuclear cells and tonsil explants. Comparative and longitudinal infection studies revealed HIV-1 group-specific activity patterns: CCR5-using (R5) viruses from group M varied considerably in their replicative capacity but showed similar levels of cytopathicity. In contrast, R5 isolates from group O were relatively uniform in their replicative fitness but displayed a high and unprecedented variability in their potential to deplete CD4 T cells. Two R5 group O isolates were identified that cause massive depletion of CD4 T cells, to an extent comparable to CXCR4-using viruses and not documented for any R5 isolate from group M. Intergroup comparisons found a five- to eightfold lower replicative fitness of isolates from group O than for isolates from group M yet a similar overall intrinsic pathogenicity in tonsil cultures. This study establishes biological ex vivo characteristics of HIV-1 group O primary isolates. The current findings challenge the belief that a grossly reduced replicative fitness or inherently impaired cytopathicity of viruses from this group underlies their low global prevalence.
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Affiliation(s)
- Silvia Geuenich
- Department of Virology, University of Heidelberg, Heidelberg, Germany
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21
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Richards KH, Clapham PR. Human immunodeficiency viruses: propagation, quantification, and storage. ACTA ACUST UNITED AC 2008; Chapter 15:Unit15J.1. [PMID: 18770581 DOI: 10.1002/9780471729259.mc15j01s02] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Described in this unit are basic protocols frequently used in the research of human immunodeficiency viruses (HIVs). Provided are methods for propagating and quantifying HIV, as well as recommendations for long-term storage. Background information about these methods is also provided and includes their advantages, disadvantages, and troubleshooting.
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Affiliation(s)
- Kathryn H Richards
- University of Massachusetts, Medical School, Worcester, Massachusetts, USA
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22
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Troyer RM, Garver KA, Ranson JC, Wargo AR, Kurath G. In vivo virus growth competition assays demonstrate equal fitness of fish rhabdovirus strains that co-circulate in aquaculture. Virus Res 2008; 137:179-88. [PMID: 18703096 DOI: 10.1016/j.virusres.2008.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2008] [Revised: 07/03/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
Abstract
A novel virus growth competition assay for determining relative fitness of RNA virus variants in vivo has been developed using the fish rhabdovirus, Infectious hematopoietic necrosis virus (IHNV), in juvenile rainbow trout (Oncorhynchus mykiss). We have conducted assays with IHNV isolates designated B, C, and D, representing the three most common genetic subtypes that co-circulate in Idaho trout farm aquaculture. In each assay, groups of 30 fish were immersed in a 1:1 mixture of two genotypes of IHNV, and then held in individual beakers for a 72h period of in vivo competitive virus replication. Progeny virus populations in each fish were analyzed for the presence and proportion of each viral genotype. In two independent assays of the B:C isolate pair, and two assays of the B:D pair, all fish were co-infected and there was a high level of fish-to-fish variation in the ratio of the two competing genotypes. However, in each assay the average ratio in the 30-fish group was not significantly different from the input ratio of 1:1, indicating equal or nearly equal viral fitness on a host population basis, under the conditions tested.
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Affiliation(s)
- Ryan M Troyer
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
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23
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Monitoring early fusion dynamics of human immunodeficiency virus type 1 at single-molecule resolution. J Virol 2008; 82:7022-33. [PMID: 18480458 DOI: 10.1128/jvi.00053-08] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fusion of human immunodeficiency virus type 1 (HIV-1) to host cells is a dynamic process governed by the interaction between glycoproteins on the viral envelope and the major receptor, CD4, and coreceptor on the surface of the cell. How these receptors organize at the virion-cell interface to promote a fusion-competent site is not well understood. Using single-molecule force spectroscopy, we map the tensile strengths, lifetimes, and energy barriers of individual intermolecular bonds between CCR5-tropic HIV-1 gp120 and its receptors CD4 and CCR5 or CXCR4 as a function of the interaction time with the cell. According to the Bell model, at short times of contact between cell and virion, the gp120-CD4 bond is able to withstand forces up to 35 pN and has an initial lifetime of 0.27 s and an intermolecular length of interaction of 0.34 nm. The initial bond also has an energy barrier of 6.7 k(B)T (where k(B) is Boltzmann's constant and T is absolute temperature). However, within 0.3 s, individual gp120-CD4 bonds undergo rapid destabilization accompanied by a shortened lifetime and a lowered tensile strength. This destabilization is significantly enhanced by the coreceptor CCR5, not by CXCR4 or fusion inhibitors, which suggests that it is directly related to a conformational change in the gp120-CD4 bond. These measurements highlight the instability and low tensile strength of gp120-receptor bonds, uncover a synergistic role for CCR5 in the progression of the gp120-CD4 bond, and suggest that the cell-virus adhesion complex is functionally arranged about a long-lived gp120-coreceptor bond.
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Geuenich S, Goffinet C, Venzke S, Nolkemper S, Baumann I, Plinkert P, Reichling J, Keppler OT. Aqueous extracts from peppermint, sage and lemon balm leaves display potent anti-HIV-1 activity by increasing the virion density. Retrovirology 2008; 5:27. [PMID: 18355409 PMCID: PMC2288616 DOI: 10.1186/1742-4690-5-27] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 03/20/2008] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Aqueous extracts from leaves of well known species of the Lamiaceae family were examined for their potency to inhibit infection by human immunodeficiency virus type 1 (HIV-1). RESULTS Extracts from lemon balm (Melissa officinalis L.), peppermint (Mentha x piperita L.), and sage (Salvia officinalis L.) exhibited a high and concentration-dependent activity against the infection of HIV-1 in T-cell lines, primary macrophages, and in ex vivo tonsil histocultures with 50% inhibitory concentrations as low as 0.004%. The aqueous Lamiaceae extracts did not or only at very high concentrations interfere with cell viability. Mechanistically, extract exposure of free virions potently and rapidly inhibited infection, while exposure of surface-bound virions or target cells alone had virtually no antiviral effect. In line with this observation, a virion-fusion assay demonstrated that HIV-1 entry was drastically impaired following treatment of particles with Lamiaceae extracts, and the magnitude of this effect at the early stage of infection correlated with the inhibitory potency on HIV-1 replication. Extracts were active against virions carrying diverse envelopes (X4 and R5 HIV-1, vesicular stomatitis virus, ecotropic murine leukemia virus), but not against a non-enveloped adenovirus. Following exposure to Lamiaceae extracts, the stability of virions as well as virion-associated levels of envelope glycoprotein and processed Gag protein were unaffected, while, surprisingly, sucrose-density equilibrium gradient analyses disclosed a marked increase of virion density. CONCLUSION Aqueous extracts from Lamiaceae can drastically and rapidly reduce the infectivity of HIV-1 virions at non-cytotoxic concentrations. An extract-induced enhancement of the virion's density prior to its surface engagement appears to be the most likely mode of action. By harbouring also a strong activity against herpes simplex virus type 2, these extracts may provide a basis for the development of novel virucidal topical microbicides.
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Affiliation(s)
- Silvia Geuenich
- Department of Virology, University of Heidelberg, Heidelberg, Germany.
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25
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Nora T, Bouchonnet F, Labrosse B, Charpentier C, Mammano F, Clavel F, Hance AJ. Functional diversity of HIV-1 envelope proteins expressed by contemporaneous plasma viruses. Retrovirology 2008; 5:23. [PMID: 18312646 PMCID: PMC2270869 DOI: 10.1186/1742-4690-5-23] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 02/29/2008] [Indexed: 11/10/2022] Open
Abstract
Background Numerous studies have shown that viral quasi-species with genetically diverse envelope proteins (Env) replicate simultaneously in patients infected with the human immunodeficiency virus type 1 (HIV-1). Less information is available concerning the extent that envelope sequence diversity translates into a diversity of phenotypic properties, including infectivity and resistance to entry inhibitors. Methods To study these questions, we isolated genetically distinct contemporaneous clonal viral populations from the plasma of 5 HIV-1 infected individuals (n = 70), and evaluated the infectivity of recombinant viruses expressing Env proteins from the clonal viruses in several target cells. The sensitivity to entry inhibitors (enfuvirtide, TAK-799), soluble CD4 and monoclonal antibodies (2G12, 48d, 2F5) was also evaluated for a subset of the recombinant viruses (n = 20). Results Even when comparisons were restricted to viruses with similar tropism, the infectivity for a given target cell of viruses carrying different Env proteins from the same patient varied over an approximately 10-fold range, and differences in their relative ability to infect different target cells were also observed. Variable region haplotypes associated with high and low infectivity could be identified for one patient. In addition, clones carrying unique mutations in V3 often displayed low infectivity. No correlation was observed between viral infectivity and sensitivity to inhibition by any of the six entry inhibitors evaluated, indicating that these properties can be dissociated. Significant inter-patient differences, independent of infectivity, were observed for the sensitivity of Env proteins to several entry inhibitors and their ability to infect different target cells. Conclusion These findings demonstrate the marked functional heterogeneity of HIV-1 Env proteins expressed by contemporaneous circulating viruses, and underscore the advantage of clonal analyses in characterizing the spectrum of functional properties of the genetically diverse viral populations present in a given patient.
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Affiliation(s)
- Tamara Nora
- Unité de Recherche Antivirale, INSERM U 552, Université Denis Diderot Paris 7, Paris F-75018, France.
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26
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Garcia-Perez J, Perez-Olmeda M, Sanchez-Palomino S, Perez-Romero P, Alcami J. A new strategy based on recombinant viruses for assessing the replication capacity of HIV-1. HIV Med 2008; 9:160-71. [PMID: 18217999 DOI: 10.1111/j.1468-1293.2007.00540.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE In heavily pretreated patients, resistance mutations arise in both protease (PR) and reverse transcriptase (RT) sequences; however, the relative impact of PR and RT mutations on viral fitness cannot be evaluated with the majority of systems. To address this issue we have developed a model based on recombinant viruses (RVs) that allows the analysis of the replication capacity (RC) of viral populations in which PR and RT are cloned either in combination or separately. METHODS RVs were generated for full-length polymerase (pol) gene, PR or RT sequences from nine naïve and 14 heavily pretreated HIV-infected patients in therapeutic failure. The relative RC was assessed by comparing luciferase activity between mutant RV and wild-type (wt) isolates. RESULTS A strong decrease (>60%) in the RC of the pol RV population was observed in the 14 heavily pretreated patients as compared with the wt RVs. The analysis of PR and RT RVs from these patients showed that the decrease in RC was mainly attributable to PR sequences in three of these 14 patients and to RT sequences in seven of these patients. In the four remaining patients, PR and RT sequences independently reduced the RC of the RVs to similar extents. CONCLUSIONS Different patterns of mutations in either PR or RT have a strong impact on RC in highly experienced HIV-infected patients.
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Affiliation(s)
- J Garcia-Perez
- AIDS Immunopathology Unit, National Centre of Microbiology, Instituto de Salud Carlos III, Madrid, Spain
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27
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Quiñones-Mateu ME, Moore-Dudley DM, Jegede O, Weber J, J Arts E. Viral drug resistance and fitness. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2008; 56:257-96. [PMID: 18086415 DOI: 10.1016/s1054-3589(07)56009-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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28
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Anastassopoulou CG, Marozsan AJ, Matet A, Snyder AD, Arts EJ, Kuhmann SE, Moore JP. Escape of HIV-1 from a small molecule CCR5 inhibitor is not associated with a fitness loss. PLoS Pathog 2007; 3:e79. [PMID: 17542646 PMCID: PMC1885273 DOI: 10.1371/journal.ppat.0030079] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 04/18/2007] [Indexed: 11/19/2022] Open
Abstract
Fitness is a parameter used to quantify how well an organism adapts to its environment; in the present study, fitness is a measure of how well strains of human immunodeficiency virus type 1 (HIV-1) replicate in tissue culture. When HIV-1 develops resistance in vitro or in vivo to antiretroviral drugs such as reverse transcriptase or protease inhibitors, its fitness is often impaired. Here, we have investigated whether the development of resistance in vitro to a small molecule CCR5 inhibitor, AD101, has an associated fitness cost. To do this, we developed a growth-competition assay involving dual infections with molecularly cloned viruses that are essentially isogenic outside the env genes under study. Real-time TaqMan quantitative PCR (QPCR) was used to quantify each competing virus individually via probes specific to different, phenotypically silent target sequences engineered within their vif genes. Head-to-head competition assays of env clones derived from the AD101 escape mutant isolate, the inhibitor-sensitive parental virus, and a passage control virus showed that AD101 resistance was not associated with a fitness loss. This observation is consistent with the retention of the resistant phenotype when the escape mutant was cultured for a total of 20 passages in the absence of the selecting compound. Amino acid substitutions in the V3 region of gp120 that confer complete AD101 resistance cause a fitness loss when introduced into an AD101-sensitive, parental clone; however, in the resistant isolate, changes elsewhere in env that occurred prior to the substitutions within V3 appear to compensate for the adverse effect of the V3 changes on replicative capacity. These in vitro studies may have implications for the development and management of resistance to other CCR5 inhibitors that are being evaluated clinically for the treatment of HIV-1 infection.
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Affiliation(s)
- Cleo G Anastassopoulou
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Andre J Marozsan
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Alexandre Matet
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Amy D Snyder
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Eric J Arts
- Division of Infectious Diseases, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Shawn E Kuhmann
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
- * To whom correspondence should be addressed. E-mail: (SEK); (JPM)
| | - John P Moore
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, United States of America
- * To whom correspondence should be addressed. E-mail: (SEK); (JPM)
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Dykes C, Demeter LM. Clinical significance of human immunodeficiency virus type 1 replication fitness. Clin Microbiol Rev 2007; 20:550-78. [PMID: 17934074 PMCID: PMC2176046 DOI: 10.1128/cmr.00017-07] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The relative fitness of a variant, according to population genetics theory, is that variant's relative contribution to successive generations. Most drug-resistant human immunodeficiency virus type 1 (HIV-1) variants have reduced replication fitness, but at least some of these deficits can be compensated for by the accumulation of second-site mutations. HIV-1 replication fitness also appears to influence the likelihood of a drug-resistant mutant emerging during treatment failure and is postulated to influence clinical outcomes. A variety of assays are available to measure HIV-1 replication fitness in cell culture; however, there is no agreement regarding which assays best correlate with clinical outcomes. A major limitation is that there is no high-throughput assay that incorporates an internal reference strain as a control and utilizes intact virus isolates. Some retrospective studies have demonstrated statistically significant correlations between HIV-1 replication fitness and clinical outcomes in some patient populations. However, different studies disagree as to which clinical outcomes are most closely associated with fitness. This may be in part due to assay design, sample size limitations, and differences in patient populations. In addition, the strength of the correlations between fitness and clinical outcomes is modest, suggesting that, at present, it would be difficult to utilize these assays for clinical management.
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Affiliation(s)
- Carrie Dykes
- Infectious Diseases Division, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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Manrique A, Rusert P, Joos B, Fischer M, Kuster H, Leemann C, Niederöst B, Weber R, Stiegler G, Katinger H, Günthard HF, Trkola A. In vivo and in vitro escape from neutralizing antibodies 2G12, 2F5, and 4E10. J Virol 2007; 81:8793-808. [PMID: 17567707 PMCID: PMC1951363 DOI: 10.1128/jvi.00598-07] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 03/28/2007] [Indexed: 02/07/2023] Open
Abstract
Recently, passive immunization of human immunodeficiency virus (HIV)-infected individuals with monoclonal antibodies (MAbs) 2G12, 2F5, and 4E10 provided evidence of the in vivo activity of 2G12 but raised concerns about the function of the two membrane-proximal external region (MPER)-specific MAbs (A. Trkola, H. Kuster, P. Rusert, B. Joos, M. Fischer, C. Leemann, A. Manrique, M. Huber, M. Rehr, A. Oxenius, R. Weber, G. Stiegler, B. Vcelar, H. Katinger, L. Aceto, and H. F. Gunthard, Nat. Med. 11:615-622, 2005). In the light of MPER-targeting vaccines under development, we performed an in-depth analysis of the emergence of mutations conferring resistance to these three MAbs to further elucidate their activity. Clonal analysis of the MPER of plasma virus samples derived during antibody treatment confirmed that no changes in this region had occurred in vivo. Sequence analysis of the 2G12 epitope relevant N-glycosylation sites of viruses derived from 13 patients during the trial supported the phenotypic evaluation, demonstrating that mutations in these sites are associated with resistance. In vitro selection experiments with isolates of four of these individuals corroborated the in vivo finding that virus strains rapidly escape 2G12 pressure. Notably, in vitro resistance mutations differed, in most cases, from those found in vivo. Importantly, in vitro selection with 2F5 and 4E10 demonstrated that resistance to these MAbs can be difficult to achieve and can lead to selection of variants with impaired infectivity. This remarkable vulnerability of the virus to interference within the MPER calls for a further evaluation of the safety and efficacy of MPER-targeting therapeutic and vaccination strategies.
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Affiliation(s)
- Amapola Manrique
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland
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Chinnadurai R, Rajan D, Münch J, Kirchhoff F. Human immunodeficiency virus type 1 variants resistant to first- and second-version fusion inhibitors and cytopathic in ex vivo human lymphoid tissue. J Virol 2007; 81:6563-72. [PMID: 17428857 PMCID: PMC1900115 DOI: 10.1128/jvi.02546-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) fusion inhibitors blocking viral entry by binding the gp41 heptad repeat 1 (HR1) region offer great promise for antiretroviral therapy, and the first of these inhibitors, T20 (Fuzeon; enfuvirtide), is successfully used in the clinic. It has been reported previously that changes in the 3-amino-acid GIV motif at positions 36 to 38 of gp41 HR1 mediate resistance to T20 but usually not to second-version fusion inhibitors, such as T1249, which target an overlapping but distinct region in HR1 including a conserved hydrophobic pocket (HP). Based on the common lack of cross-resistance and the difficulty of selecting T1249-resistant HIV-1 variants, it has been suggested that the determinants of resistance to first- and second-version fusion inhibitors may be different. To further assess HIV-1 resistance to fusion inhibitors and to analyze where changes in HR1 are tolerated, we randomized 16 codons in the HR1 region, including those making contact with HR2 codons and/or encoding residues in the GIV motif and the HP. We found that changes only at positions 37I, 38V, and 40Q near the N terminus of HR1 were tolerated. The propagation of randomly gp41-mutated HIV-1 variants in the presence of T1249 allowed the effective selection of highly resistant forms, all containing changes in the IV residues. Overall, the extent of T1249 resistance was inversely correlated to viral fitness and cytopathicity. Notably, one HIV-1 mutant showing approximately 10-fold-reduced susceptibility to T1249 inhibition replicated with wild type-like kinetics and caused substantial CD4+-T-cell depletion in ex vivo-infected human lymphoid tissue in the presence and absence of an inhibitor. Taken together, our results show that the GIV motif also plays a key role in resistance to second-version fusion inhibitors and suggest that some resistant HIV-1 variants may be pathogenic in vivo.
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Affiliation(s)
- Raghavan Chinnadurai
- Institute for Virology, University Clinic, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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32
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Humbert M, Antoni S, Brill B, Landersz M, Rodes B, Soriano V, Wintergerst U, Knechten H, Staszewski S, von Laer D, Dittmar MT, Dietrich U. Mimotopes selected with antibodies from HIV-1-neutralizing long-term non-progressor plasma. Eur J Immunol 2007; 37:501-15. [PMID: 17236253 DOI: 10.1002/eji.200636560] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A promising approach to identify HIV-1 vaccine candidates is to dissect the natural immune response against the virus in persons controlling the infection over decades without any antiviral therapy. Here we focus on a group of such persons, eight long-term non-progressors (LTNP), in which we proved the presence of broadly neutralizing antibodies against HIV-1 in the plasma as very likely cause for their LTNP status. The aim of this study was to identify the epitopes for these neutralizing antibodies, as these should represent immunogens potentially able to elicit neutralizing antibodies upon vaccination. We screened random peptide phage libraries with plasma antibodies from eight LTNP. After several rounds of positive and negative selection, about 700 HIV-specific mimotopes were sequenced. The mimotope sequences were analyzed for homology to HIV-1 Env, in particular for their capacity to represent conformational epitopes on the surface of the gp120 structure using our software 3DEX. Related phage groups were analyzed for crossreactivity with the LTNP plasma by ELISA as well as for their capacity to induce HIV-1-neutralizing antibodies in mice. Based on this study interesting mimotopes can now be selected for further immunization studies.
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Affiliation(s)
- Michael Humbert
- Georg-Speyer-Haus, Institute for Biomedical Research, Frankfurt am Main, Germany
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33
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Weber J, Weberova J, Carobene M, Mirza M, Martinez-Picado J, Kazanjian P, Quiñones-Mateu ME. Use of a novel assay based on intact recombinant viruses expressing green (EGFP) or red (DsRed2) fluorescent proteins to examine the contribution of pol and env genes to overall HIV-1 replicative fitness. J Virol Methods 2006; 136:102-17. [PMID: 16690137 DOI: 10.1016/j.jviromet.2006.04.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 03/31/2006] [Accepted: 04/04/2006] [Indexed: 12/21/2022]
Abstract
Multiple studies have described a reduction in the replicative fitness of HIV-1 isolates harboring mutations that confer resistance to antiretroviral drugs. Contradictory results, however, have been obtained depending on the methodology used in each study (Quinones-Mateu, M.E., Arts, E.J., 2002. Fitness of drug resistant HIV-I: methodology and clinical implications. Drug Resist. Update 5, 224-233), affecting our understanding of the potential relationship of viral replicative fitness with HIV-1 disease. It has been demonstrated previously that both pol and env genes play a major role in HIV-1 replicative fitness of clinical isolates. Therefore, measuring clinically relevant replicative fitness using recombinant viruses where a single mutation and/or viral gene have been introduced does not seem like a reasonable approach in this era of multi-target antiretroviral therapy. A novel method was developed to measure HIV-1 replicative fitness based on recombinant viruses expressing the enhanced green fluorescent (EGFP) or the Discosoma sp. red fluorescent (DsRed2) proteins in a HIV-1NL4-3 backbone. Contrary to previous designs to analyze HIV-1 fitness, these replication competent viruses were created in an intact viral genetic background (without deleting or affecting the expression of any viral gene). This new system was used to evaluate the contribution of drug-resistance mutations in the pol and env genes to overall viral replicative fitness (in the presence and absence of drug pressure) using direct growth competition experiments. Mutations in pol showed a stronger effect on HIV-1 replicative fitness than mutations in the env gene associated with resistance to enfuvirtide, corroborating the plasticity of the later gene to accept mutations and the sensibility of the protease and reverse transcriptase enzymes to drug-associated primary mutations. In conclusion, a new protocol was used to measure HIV-1 replicative fitness in either the presence or absence of antiretroviral drugs, which may be used as a high-throughput assay to help us understand the clinical significance of viral fitness.
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Affiliation(s)
- Jan Weber
- Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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Quiñones-Mateu ME, Arts EJ. Virus fitness: concept, quantification, and application to HIV population dynamics. Curr Top Microbiol Immunol 2006; 299:83-140. [PMID: 16568897 DOI: 10.1007/3-540-26397-7_4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Viral fitness has been broadly studied during the past three decades, mainly to test evolutionary models and population theories difficult to analyze and interpret with more complex organisms. More recent studies, however, are focused in the role of fitness on viral transmission, pathogenesis, and drug resistance. Here, we used human immunodeficiency virus (HIV) as one of the most relevant models to evaluate the importance of viral quasispecies and fitness in HIV evolution, population dynamics, disease progression, and potential clinical implications.
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Affiliation(s)
- M E Quiñones-Mateu
- Department of Molecular Genetics, Section Virology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue/NN10, Cleveland, OH 44195, USA.
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Lohrengel S, Hermann F, Hagmann I, Oberwinkler H, Scrivano L, Hoffmann C, von Laer D, Dittmar MT. Determinants of human immunodeficiency virus type 1 resistance to membrane-anchored gp41-derived peptides. J Virol 2005; 79:10237-46. [PMID: 16051817 PMCID: PMC1182644 DOI: 10.1128/jvi.79.16.10237-10246.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The expression of a membrane-anchored gp41-derived peptide (M87) has been shown to confer protection from infection through human immunodeficiency virus type 1 (HIV-1) (Hildinger et al., J. Virol. 75:3038-3042, 2001). In an effort to characterize the mechanism of action of this membrane-anchored peptide in comparison to the soluble peptide T-20, we selected resistant variants of HIV-1(NL4-3) and HIV-1(BaL) by serial virus passage using PM1 cells stably expressing peptide M87. Sequence analysis of the resistant isolates showed different patterns of selected point mutations in heptad repeat regions 1 and 2 (HR1 and HR2, respectively) for the two viruses analyzed. For HIV-1(NL4-3) a single amino acid change at position 33 in HR1 (L33S) was selected, whereas for HIV-1(BaL) the majority of the sequences obtained showed two amino acid changes, one in HR1 and one in HR2 (I48V/N126K). In both selections the most important contiguous 3-amino-acid sequence, GIV, within HR1, associated with resistance to soluble T-20, was not changed. Site-directed mutagenesis studies confirmed the importance of the characterized point mutations to confer resistance to M87 as well as to soluble T-20 and T-649. Replication capacity and dual-color competition assays revealed that the double mutation I48V/N126K in HIV-1(BaL) results in a strong reduction of viral fitness, whereas the L33S mutation in HIV-1(NL4-3) did enhance viral fitness compared to the respective parental viruses. However, the selected point mutations did not confer resistance to the more recently described optimized membrane-anchored fusion inhibitor M87o (Egelhofer et al., J. Virol. 78:568-575, 2004), strengthening the importance of this novel antiviral concept for gene therapy approaches.
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Affiliation(s)
- Sabine Lohrengel
- Abt. Virologie, Hygiene-Institut, Universität Heidelberg, D-69120 Heidelberg, Germany
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