1
|
Xue B, Mizianty MJ, Kurgan L, Uversky VN. Protein intrinsic disorder as a flexible armor and a weapon of HIV-1. Cell Mol Life Sci 2012; 69:1211-59. [PMID: 22033837 PMCID: PMC11114566 DOI: 10.1007/s00018-011-0859-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/28/2011] [Accepted: 10/03/2011] [Indexed: 01/19/2023]
Abstract
Many proteins and protein regions are disordered in their native, biologically active states. These proteins/regions are abundant in different organisms and carry out important biological functions that complement the functional repertoire of ordered proteins. Viruses, with their highly compact genomes, small proteomes, and high adaptability for fast change in their biological and physical environment utilize many of the advantages of intrinsic disorder. In fact, viral proteins are generally rich in intrinsic disorder, and intrinsically disordered regions are commonly used by viruses to invade the host organisms, to hijack various host systems, and to help viruses in accommodation to their hostile habitats and to manage their economic usage of genetic material. In this review, we focus on the structural peculiarities of HIV-1 proteins, on the abundance of intrinsic disorder in viral proteins, and on the role of intrinsic disorder in their functions.
Collapse
Affiliation(s)
- Bin Xue
- Department of Molecular Medicine, University of South Florida, College of Medicine, 12901 Bruce B. Downs Blvd, MDC07, Tampa, FL 33612 USA
| | - Marcin J. Mizianty
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4 Canada
| | - Lukasz Kurgan
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4 Canada
| | - Vladimir N. Uversky
- Department of Molecular Medicine, University of South Florida, College of Medicine, 12901 Bruce B. Downs Blvd, MDC07, Tampa, FL 33612 USA
- Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region Russia
| |
Collapse
|
2
|
A V3 loop-dependent gp120 element disrupted by CD4 binding stabilizes the human immunodeficiency virus envelope glycoprotein trimer. J Virol 2010; 84:3147-61. [PMID: 20089638 DOI: 10.1128/jvi.02587-09] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus (HIV-1) entry into cells is mediated by a trimeric complex consisting of noncovalently associated gp120 (exterior) and gp41 (transmembrane) envelope glycoproteins. The binding of gp120 to receptors on the target cell alters the gp120-gp41 relationship and activates the membrane-fusing capacity of gp41. Interaction of gp120 with the primary receptor, CD4, results in the exposure of the gp120 third variable (V3) loop, which contributes to binding the CCR5 or CXCR4 chemokine receptors. We show here that insertions in the V3 stem or polar substitutions in a conserved hydrophobic patch near the V3 tip result in decreased gp120-gp41 association (in the unliganded state) and decreased chemokine receptor binding (in the CD4-bound state). Subunit association and syncytium-forming ability of the envelope glycoproteins from primary HIV-1 isolates were disrupted more by V3 changes than those of laboratory-adapted HIV-1 envelope glycoproteins. Changes in the gp120 beta2, beta19, beta20, and beta21 strands, which evidence suggests are proximal to the V3 loop in unliganded gp120, also resulted in decreased gp120-gp41 association. Thus, a gp120 element composed of the V3 loop and adjacent beta strands contributes to quaternary interactions that stabilize the unliganded trimer. CD4 binding dismantles this element, altering the gp120-gp41 relationship and rendering the hydrophobic patch in the V3 tip available for chemokine receptor binding.
Collapse
|
3
|
Du SX, Xu L, Viswanathan S, Whalen RG. Inhibition of V3-specific cleavage of recombinant HIV-1 gp120 produced in Chinese hamster ovary cells. Protein Expr Purif 2008; 59:223-31. [PMID: 18406166 DOI: 10.1016/j.pep.2008.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 02/06/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Specific proteolytic cleavage of the gp120 subunit of the HIV-1 envelope (Env) glycoprotein in the third variable domain (V3) has previously been reported to occur in several cell lines, including Chinese hamster ovary cells that have been used for production of Env-based HIV vaccine candidates. Here we report that this proteolytic activity on JRCSF gp120 is dependent on cell density, medium conditions, and supernatant concentration. The resulting cleaved polypeptides cannot be separated from intact gp120 by conventional or affinity chromatography under non-reducing conditions. Inhibitor studies reveal that Pefabloc and benzamidine, but not chymostatin, block gp120 cleavage in a dose-dependent fashion, suggesting the presence of a trypsin-like serine protease in CHO-K1 cells. The proteolytic activity is increased with certain types of cell culture growth media. A combination of serum-free OptiMEM media during expression and potent protease inhibitors post-expression can effectively prevent HIV gp120 degradation. The same strategy can be applied to the expression and purification of gp120 of other strains or other forms of envelope-based vaccine candidates containing V3 sequences.
Collapse
Affiliation(s)
- Sean X Du
- Maxygen, Inc., Infectious Diseases, 515 Galveston Drive, Redwood City, CA 94063, USA
| | | | | | | |
Collapse
|
4
|
Abstract
HIV-1 infects host cells by sequential interactions of its fusion protein (gp120-gp41) with receptors CD4, CXCR4 and/or CCR5 followed by fusion of viral and host membranes. Studies indicate that additional factors such as receptor density and composition of viral and cellular lipids can dramatically modulate the fusion reaction. Lipid rafts, which primarily consist of sphingolipids and cholesterol, have been implicated for infectious route of HIV-1 entry. Plasma membrane Glycosphingolipids (GSLs) have been proposed to support HIV-1 infection in multiple ways: (a) as alternate receptor(s) for CD4-independent entry in neuronal and other cell types, (b) viral transmission, and (c) gp120-gp41-mediated membrane fusion. However, the exact mechanism(s) by which GSLs support fusion is still elusive. This article will focus on the contribution of target membrane sphingolipids and their metabolites in modulating viral entry. We will discuss the current working hypotheses underlying the mechanisms by which these lipids promote and/or block HIV-1 entry. Recent approaches in the design and development of novel glycosyl derivatives, as anti-HIV agents will be summarized.
Collapse
Affiliation(s)
- Satinder S Rawat
- Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, P.O. Box B, Bldg. 469, Rm. 211, Miller Drive, Frederick, MD 21702, USA
| | | | | |
Collapse
|
5
|
Noorbakhsh F, Vergnolle N, Hollenberg MD, Power C. Proteinase-activated receptors in the nervous system. Nat Rev Neurosci 2004; 4:981-90. [PMID: 14682360 DOI: 10.1038/nrn1255] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent data point to important roles for proteinases and their cognate proteinase-activated receptors (PARs) in the ontogeny and pathophysiology of the nervous system. PARs are a family of G-protein-coupled receptors that can affect neural cell proliferation, morphology and physiology. PARs also have important roles in neuroinflammatory and degenerative diseases such as human immunodeficiency virus-associated dementia, Alzheimer's disease and pain. These receptors might also influence the pathogenesis of stroke and multiple sclerosis, conditions in which the blood-brain barrier is disrupted. The diversity of effects of PARs on neural function and their widespread distribution in the nervous system make them attractive therapeutic targets for neurological disorders. Here, we review the roles of PARs in the central and peripheral nervous systems during health and disease, with a focus on neuroinflammatory and degenerative disorders.
Collapse
|
6
|
Barbouche R, Feyfant E, Belhaj B, Fenouillet E. Pharmacophore determination of a gp120 C terminal-derived anti-HIV peptide construct interfering with membrane fusion suggesting that processing of the gp120 C terminus is a prelude to fusion. AIDS Res Hum Retroviruses 2002; 18:201-6. [PMID: 11839154 DOI: 10.1089/08892220252781257] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
A multiple antigen peptide [CLIV; (PTKAKRR1VVQREKR2)4-K2-K-betaA] from the C terminus of the gp120 subunit of HIV Env inhibits Env-mediated cell-to-cell fusion through direct interference with the process (Virology 2000;273:169). We have examined various CLIV analogs using a cell-to-cell fusion assay, receptor binding assays, and molecular modeling to further address the characteristics of the peptide responsible for its anti-HIV activity. We show that (1) CLIV does not interfere with Env binding to CD4 and does not interact with the binding site of Env on CXCR4; (2) CLIV does not inhibit protease activities already reported to play a role in fusion; and (3) the pharmacophore is composed of cleavage site1 with amino acid residues at its C terminal end. Based on our data and on the literature, we propose that CLIV interferes with processing of the gp120 C terminus at site1 by the lymphocyte surface after CD4 binding. Our hypothesis implies that the cleavage region of Env is submitted to a stepwise processing including the known intracellular cleavage of gp160 at site2 in order to set the activation of the fusion peptide and a yet unexplored cleavage at site1 by the target cell surface that triggers fusion.
Collapse
Affiliation(s)
- R Barbouche
- CNRS, Faculté de Médecine Nord, Marseille, France and Institut Universitaire de Sciences Biologiques, Monastir, Tunisia
| | | | | | | |
Collapse
|
7
|
Albright AV, Martín J, O'Connor M, González-Scarano F. Interactions between HIV-1 gp120, chemokines, and cultured adult microglial cells. J Neurovirol 2001; 7:196-207. [PMID: 11517394 DOI: 10.1080/13550280152403245] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
HIV dementia (HIVD), a disease that is apparently mediated by neurotoxins and viral proteins secreted by HIV infected microglia, is characterized neuropathologically by an increased number of activated microglia in the brains of affected individuals. Consequently, the rational design of potential therapeutic strategies should take into account the mechanisms that lead to microglial activation and to their increased prominence in the adult brain. In this regard, one leading hypothesis proposes that microglia are recruited to specific sites in the central nervous system (CNS) as a result of interactions between microglial chemokine receptors and chemokines, or even the viral glycoprotein gp120, which binds chemokine receptors in the process of cellular entry. Adult microglia express the functional chemokine receptors CCR5 and CXCR4 molecules that mediate chemotaxis in these and other cell types. We determined that purified adult microglial cultures contain a heterogeneous population with respect to their ability to respond to the alpha- and beta-chemokines, SDF1alpha, and MIP-1beta. A mean of 14.6% of the microglia assayed responded to both alpha- and beta-chemokines (CCR5(+)CXCR4(+) phenotype); 45.4% of microglia were phenotyped as CCR5(+)CXCR4(-); 12.9% of the microglia were CXCR4(+)CCR5(-); and 27.0% of microglia did not respond to either chemokine. No increase in intracellular calcium levels was seen in the vast majority of microglia exposed to the soluble HIV envelope protein, gp120, or to HIV envelope (gp120/gp41) expressed on MLV virus pseudotypes. However, exposure of microglia to soluble fractalkine or to other chemokines resulted in an intracellular calcium flux. Our results raise the possibility of microglial heterogeneity with respect to their response to chemokines, and indicate that any effects due to gp120 are likely to be considerably less robust than the response of microglia to the natural ligands of their chemokine receptors, for example SDF1alpha and MIP-1beta.
Collapse
Affiliation(s)
- A V Albright
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6146, USA.
| | | | | | | |
Collapse
|
8
|
Shugars DC, Alexander AL, Fu K, Freel SA. Endogenous salivary inhibitors of human immunodeficiency virus. Arch Oral Biol 1999; 44:445-53. [PMID: 10401522 DOI: 10.1016/s0003-9969(99)00003-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) is rarely transmitted through salivary secretions, due in part to the presence of endogenous inhibitors. Here, the protective characteristics of the intraoral environment are summarized and inhibitory factors that reduce HIV-1 infectivity in vitro described, focusing on secretory leucocyte protease inhibitor (SLPI), a 12-kDa mucosal protein that blocks HIV infection in several cell-culture systems. SLPI appears to interact with a cellular surface molecule to limit viral entry into target cells. To determine whether the inhibitor has a similar role in vivo, the contribution of salivary SLPI to anti-HIV-1 activity was assessed. Whole unstimulated filtered salivas from infected and uninfected donors contained similar concentrations of the inhibitor. Depletion from SLPI filtered saliva produced a corresponding loss of inhibitory activity. In general, filtered whole salivas obtained from 10 donors had antiviral activities that correlated positively with SLPI concentrations. However, some samples having SLPI well below the concentration required for inhibitory activity in vitro exhibited modest inhibition, suggesting the presence of other anti-HIV-1 components in oral fluids. Thus, SLPI is a major but not sole inhibitor of this virus in saliva.
Collapse
Affiliation(s)
- D C Shugars
- Department of Dental Ecology, School of Dentistry, University of North Carolina at Chapel Hill, USA
| | | | | | | |
Collapse
|
9
|
Papandreou MJ, Fenouillet E. Effect of changes in the glycosylation of the human immunodeficiency virus type 1 envelope on the immunoreactivity and sensitivity to thrombin of its third variable domain. Virology 1998; 241:163-7. [PMID: 9454727 DOI: 10.1006/viro.1997.8930] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The influence of HIV Env glycosylation on the conformation of the third variable domain (V3) of Env was studied by both deglycosylation of mature Env and the use of Env produced by recombinant systems in which alpha-glucosidase activity was inhibited by either deoxynojirimycin (DNM) or mutation. Selective deglycosylation affected anti-V3 antibody binding. The immunoreactivity and sensitivity to thrombin cleavage of V3 presented on Env produced in baby hamster kidney cells were changed by DNM treatment. In contrast, Env expressed in alpha-glucosidase I-deficient Chinese hamster ovary cells or in their parental cells treated by DNM fully retained these V3 properties. These results are discussed in relation to the inconsistent data obtained on V3 property changes resulting from Env glycosylation changes.
Collapse
|
10
|
Niwa Y, Yano M, Futaki S, Okumura Y, Kido H. T-cell membrane-associated serine protease, tryptase TL2, binds human immunodeficiency virus type 1 gp120 and cleaves the third-variable-domain loop of gp120. Neutralizing antibodies of human immunodeficiency virus type 1 inhibit cleavage of gp120. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:64-70. [PMID: 8620895 DOI: 10.1111/j.1432-1033.1996.0064n.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It has been suggested that the third variable domain (V3) loop of human immunodeficiency virus type 1 (HIV-1) gp120 has to interact with a cell-surface-associated protease(s) that acts as a cofactor after binding of gp120 to the CD4 receptor during entry of HIV-1 into susceptible cells. We isolated the membrane-associated serine protease, tryptase TL2, from human CD4-positive lymphocytes. This enzyme specifically binds gp120 through interaction with its V3 domain. To investigate the role of tryptase TL2 in HIV infection, we examined the affinity of the interaction and the proteolytic susceptibility of various recombinant gp120 expressed in mammalian cells to the enzyme, and we determined the cleavage sites. Tryptase TL2 bound gp120 with an apparent dissociation constant of 38 nM. The affinity was lower than that of gp120 for CD4 which suggests that gp120 initially binds to CD4, followed by interaction with tryptase TL2 which is localized close to CD4 on the cell surface. After binding, tryptase TL2 cleaved recombinant gp120 expressed in mammalian cells into two protein species of 70 kDa and 50 kDa but did not cleave gp120 expressed in insect cells, which indicates that the structure of the oligosaccharides linked to the polypeptide backbone of gp120 affects the proteolytic susceptibility. Cleavage was specifically inhibited by a neutralizing antibody against the V3 loop. Cleavage-site determination revealed that tryptase TL2 cleaved gp120 at various sites in the V3 in a strain-dependent manner. The amino acid variability at the cleavage site(s) in almost all HIV-1 isolates was restricted to amino acids which are susceptible to the chymotryptic and/or tryptic activities of tryptase TL2.
Collapse
Affiliation(s)
- Y Niwa
- Division of Enzyme Chemistry, University of Tokushima, Japan
| | | | | | | | | |
Collapse
|
11
|
Olaleye DO, Sheng Z, Howard TM, Rasheed S. Isolation and characterization of a new subtype A variant of human immunodeficiency virus type I from Nigeria. Trop Med Int Health 1996; 1:97-106. [PMID: 8673828 DOI: 10.1046/j.1365-3156.1996.d01-4.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have isolated a new variant of HIV-1 from Nigeria, Africa. The virus was recovered from the peripheral blood mononuclear cells (PBMCs) of an apparently healthy 23-year-old male from Ibadan, Nigeria. The in vitro studies indicated that the virus was highly cytopathic and replicated well in normal PBMCs, established T-cell lines and the monocytic cell line U937. The highest replicative titre of the virus was obtained in freshly isolated primary macrophage/monocyte cells which also showed the least cytopathology. Most other cultures showed single-cell cytolysis and giant cells, and syncytia were not induced in the HTLV-1 infected MT-2 cells. Since no HIV strain has been isolated from Nigeria, we obtained cDNA clones containing the env gene, to further characterize the Nigerian virus. Based on the DNA sequence analysis of 14 clones containing the coding region for its gp 120 protein, the Nigerian HIV isolate has been classified as HIV-1 subtype A. Only one subtype A virus from Rwanda has been characterized and this virus has not been shown to exhibit extreme cytopathicity in various cell types as was observed with the Nigerian strain. Further, the ability of this virus to grow well in lymphocytes, monocytes and macrophages and to exhibit cytopathicity without causing syncytia are uncommon properties distinguishing the Nigerian virus from other HIV-1 strains. Since most macrophage-tropic viruses have been associated with 'neurotropism', the isolation of an HIV-1 strain from the blood of an individual with no known neurological disorder indicates that this rapidly replicating cytopathic virus, with a broad host range, may play an important role in the pathogenesis of HIV disease. This represents the first report of an HIV-1 isolate from Nigeria.
Collapse
Affiliation(s)
- D O Olaleye
- Laboratory of Viral Oncology and AIDS Research, University of Southern California, School of Medicine, Los Angeles 90032-3626, USA
| | | | | | | |
Collapse
|
12
|
Carrillo A, Ratner L. Human immunodeficiency virus type 1 tropism for T-lymphoid cell lines: role of the V3 loop and C4 envelope determinants. J Virol 1996; 70:1301-9. [PMID: 8551600 PMCID: PMC189948 DOI: 10.1128/jvi.70.2.1301-1309.1996] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- A Carrillo
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
13
|
Carrillo A, Ratner L. Cooperative effects of the human immunodeficiency virus type 1 envelope variable loops V1 and V3 in mediating infectivity for T cells. J Virol 1996; 70:1310-6. [PMID: 8551601 PMCID: PMC189949 DOI: 10.1128/jvi.70.2.1310-1316.1996] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Insertion of T-cell line-tropic V3 and V4 loops from the HXB2 strain into the macrophage-tropic YU-2 envelope resulted in a virus with delayed infectivity for HUT78 and Jurkat cells compared with HXB2. Sequence analysis of viral DNA derived from long-term cultures of Jurkat cells revealed a specific mutation that changed a highly conserved Asn residue in the V1 loop of Env to an Asp residue (N-136-->D). Introduction of this mutation into clones containing a T-cell line-tropic V3 loop, either with or without a T-cell line-tropic V4 loop, resulted in viruses that replicated to high levels in Jurkat cells and peripheral blood lymphocytes. The Env proteins from these constructs were expressed with the vaccinia virus/T7 hybrid system and were found to be translated, processed, and cleaved and to bind to soluble CD4 similar to the wild-type HXB2 and YU-2 Env proteins. Env-mediated fusion with HeLa T4+ cells, however, was regulated by both the altered V1 loop and T-cell line-tropic V3 loop. These results suggest that subsequent to the initial gp120-CD4 binding event, a functional interaction can occur between the altered V1 loop and T-cell line-tropic V3 loop that results in infection of Jurkat cells and peripheral blood lymphocytes.
Collapse
Affiliation(s)
- A Carrillo
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
14
|
de Vreese K, Kofler-Mongold V, Leutgeb C, Weber V, Vermeire K, Schacht S, Anné J, de Clercq E, Datema R, Werner G. The molecular target of bicyclams, potent inhibitors of human immunodeficiency virus replication. J Virol 1996; 70:689-96. [PMID: 8551604 PMCID: PMC189868 DOI: 10.1128/jvi.70.2.689-696.1996] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Bicyclams are a novel class of antiviral compounds which act as potent and selective inhibitors of the replication of human immunodeficiency virus type 1 (HIV-1) and HIV-2. They block an early step in the viral life cycle following adsorption to the CD4 receptor and preceding reverse transcription. To identify the molecular target of these compounds, we genetically analyzed variants of the HIV-1 molecular clone NL4-3, which developed resistance against two structurally related bicyclams, JM2763 and the more potent SID791. The resistant strains were obtained after long-term passaging in MT-4 cells in the presence of progressively increasing compound concentrations. Recombinants between selected genes of the resistant strains and the parental NL4-3 provirus were generated by adapting the marker rescue technique to MT-4 cells. The bicyclam-resistant phenotype was rescued by transferring the envelope gp120 gene of bicyclam-resistant virus into the NL4-3 parental genetic background. In the gp120 genes of the resistant strains, we identified several mutations leading to amino acid substitutions in the V3 loop. Furthermore, two substitutions of highly conserved amino acids in close proximity to the disulfide bridges of the V3 and V4 loops were found in both SID791- and JM2763-resistant strains. Additional mutations in regions encoding V3, C4, V5, and C5 were present in SID791-resistant viruses. Recombination experiments with overlapping parts of the envelope gene indicated that most, if not all, of the mutations were necessary to develop the fully SID791 resistant phenotype. The mutations in the C-terminal part of gp120 downstream of the V3 loop sequence conferred partial resistance to JM2763 but did not significantly decrease susceptibility to SID791. The genetic data and the biological properties of the resistant viruses point to inhibition of entry and fusion as the mode of action of the HIV-inhibitory bicyclams. A possible mechanism of binding of bicyclams to gp120 leading to inhibition of unfolding of gp120 and its shedding from the gp41 fusion domain is discussed.
Collapse
Affiliation(s)
- K de Vreese
- Rega Institute for Medical Research, Katholieke Universiteit Leuven, Belgium
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Vallejo A, Bravo R, Heredia A, Soriano V, Dronda F, Hewlett IK. Sequence analysis of the V1/V2 and V3 domains in an HIV-seronegative AIDS patient. AIDS Res Hum Retroviruses 1995; 11:1539-41. [PMID: 8679300 DOI: 10.1089/aid.1995.11.1539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- A Vallejo
- Laboratory of Molecular Virology, CBER, FDA, Rockville, Maryland 20852-1448, USA
| | | | | | | | | | | |
Collapse
|
16
|
Freed EO, Martin MA. The role of human immunodeficiency virus type 1 envelope glycoproteins in virus infection. J Biol Chem 1995; 270:23883-6. [PMID: 7592573 DOI: 10.1074/jbc.270.41.23883] [Citation(s) in RCA: 214] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- E O Freed
- Laboratory of Molecular Microbiology, NIAID, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
| | | |
Collapse
|
17
|
Ebenbichler C, McNearney T, Stoiber H, Möst J, Zangerle R, Vogetseder W, Patsch JR, Ratner L, Dierich MP. Sera from HIV-1 infected individuals in all stages of disease preferentially recognize the V3 loop of the prototypic macrophage-tropic glycoprotein gp120 ADA. Mol Immunol 1995; 32:1039-45. [PMID: 8544853 DOI: 10.1016/0161-5890(95)00083-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The outer membrane glycoprotein gp120 and the transmembrane glycoprotein gp41 are predominant targets of the humoral immune response to infection by human immunodeficiency virus type 1. The third hypervariable region (V3 loop) is the principal neutralizing domain and is the primary target of neutralizing antibodies directed against the envelope proteins of HIV-1. The V3 loop is also the major determinant for HIV-1 cell-specific tropism. To further characterize the humoral immune response directed against the gp120 envelope proteins, we expressed two prototypic gp120 envelope proteins (LAI/HXB2 and ADA) and chimeric gp120 envelope proteins in stable transfected Drosophila melanogaster Schneider 2 cells. Sera from four infected adults over the course of infection [McNearney et al. (1992) Proc. natn. Acad. Sci. U.S.A. 89, p. 10,242] were assayed for reactivity with the respective envelope proteins. Sera obtained at early stages preferentially recognized the gp120 envelope protein ADA, whereas in later stages of infection the sera showed diminished reactivity with both gp120 LAI/HXB2 and gp120 ADA. Chimeric envelope proteins revealed that the humoral response was directed primarily against the V3 loop of gp120 ADA. Furthermore, 22 sera from HIV-1 infected individuals in different stages of the disease were tested. Reactivity of sera with the gp120 envelope protein ADA was seven-fold higher than with the gp120 envelope protein LAI/HXB2. Our results suggest that the humoral immune response is preferentially elicited against the V3 loop of the prototypic macrophage-tropic gp120 envelope protein ADA.
Collapse
Affiliation(s)
- C Ebenbichler
- Institut für Hygiene und Ludwig-Boltzmann-Institut für AIDS-Forschung, Innsbruck, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Xu Y, Murakami T, Kawase S, Uchiyama T, Hattori T. Characterization of V3 loop-binding protein(s) of Molt-4 and U937 cells. AIDS Res Hum Retroviruses 1995; 11:563-70. [PMID: 7576912 DOI: 10.1089/aid.1995.11.563] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The V3 loop in gp120 of human immunodeficiency virus type 1 (HIV-1) is known as a principal neutralizing and cell-tropic determinant. Biotinylated synthetic V3 loop peptides derived from three different HIV-1 strains were used as ligands to identify the cell surface counterreceptor, which may participate in the infection of HIV-1. Two different cell lines, Molt-4 and U937, and three V3 loop peptides derived from LAVELI, HTLV-IIIMN, and HTLV-IIIB strains were used. The binding of HTLV-IIIB-derived peptide to the cell surface was confirmed using 125I-labeled surface proteins of both cell lines. The relative molecular mass of the major radioactive band on the autoradiogram was 32-33 kDa in both cell lines. A protein was purified from the plasma membrane fraction of Molt-4 cells using affinity columns coupled with three different V3 loop peptides. Two major polypeptides (32 and 33 kDa) were eluted from the affinity column. Size-exclusion chromatography showed that the protein migrated as a single peak with a molecular mass of 130 kDa. These proteins were separated by reversed-phase chromatography, which indicated that the 32-kDa protein is more hydrophobic than the 33-kDa protein in Molt-4 cells. A similar but not identical 130-kDa protein with 32- and 33-kDa polypeptides were also purified from U937 cells. These findings indicate that HIV-1 utilizes a tetrameric protein on the surface of Molt-4 and U937 cells on infection.
Collapse
Affiliation(s)
- Y Xu
- Laboratory for AIDS Immunology, Kyoto University, Japan
| | | | | | | | | |
Collapse
|
19
|
Rodriguez GE, Hard RC. IMMUNOPATHOGENESIS OF AIDS. Immunol Allergy Clin North Am 1995. [DOI: 10.1016/s0889-8561(22)00835-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
|
20
|
Kim FM, Kolson DL, Balliet JW, Srinivasan A, Collman RG. V3-independent determinants of macrophage tropism in a primary human immunodeficiency virus type 1 isolate. J Virol 1995; 69:1755-61. [PMID: 7853514 PMCID: PMC188781 DOI: 10.1128/jvi.69.3.1755-1761.1995] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Human immunodeficiency virus type 1 isolates differ in their ability to productively infect macrophages, and several groups have mapped the genetic basis for macrophage tropism to regions of env that include the third hypervariable region (V3 loop). We recently described a primary isolate (89.6) which is highly macrophage tropic and yet differs from other macrophage-tropic strains studied in that it is cytopathic in T cells. Genetic mapping of macrophage tropism determinants in this virus was done by using chimeras generated with the prototypic non-macrophage-tropic strain HXB2. Replacement of a 2.7-kb env-containing region of HXB with corresponding sequences from 89.6 conferred the macrophage-tropic phenotype, but insertion of the 89.6 V3 loop along with V4/V5 sequences did not. Conversely, placement of HXB sequences that included V3 into 89.6 did not impair this strain's ability to replicate in macrophages. Sequence analysis of V3 shows that 89.6 differs markedly from previously described macrophage-tropic consensus sequences and that it is more similar to highly charged non-macrophage-tropic strains. This suggests either that macrophage tropism is defined by structural determinants resulting from complex interactions among multiple env regions rather than V3 sequence-specific requirements or that there are multiple mechanisms by which different strains may establish productive macrophage infection. In addition, because the HXB V3 loop supports productive macrophage infection in the background of 89.6, phenotypic characterization of V3 sequences should be considered specific to the viral context in which they are placed.
Collapse
Affiliation(s)
- F M Kim
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104-6076
| | | | | | | | | |
Collapse
|
21
|
Moore JP, Trkola A, Korber B, Boots LJ, Kessler JA, McCutchan FE, Mascola J, Ho DD, Robinson J, Conley AJ. A human monoclonal antibody to a complex epitope in the V3 region of gp120 of human immunodeficiency virus type 1 has broad reactivity within and outside clade B. J Virol 1995; 69:122-30. [PMID: 7527082 PMCID: PMC188555 DOI: 10.1128/jvi.69.1.122-130.1995] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We have used virus neutralization and antibody-binding techniques to define the epitope for a human monoclonal antibody, designated 19b, within the V3 region of the gp120 surface glycoprotein of human immunodeficiency virus type 1. Unusually, the 19b epitope encompasses residues on both flanks of the V3 loop. However, 19b binding to gp120 is independent of sequences at the crown of the V3 loop, provided that they are compatible with the formation of a type II beta turn that is presumably necessary to juxtapose the antigenic residues on the V3 flanks. By comparing the V3 sequences of virus gp120s able and unable to bind 19b, we were able to define the canonical 19b epitope as -I----G--FY-T, where residues at the positions indicated by the gaps do not contribute directly to the 19b-binding site. A few conservative substitutions at the more critical residues are also compatible with 19b binding. Inspection of V3 sequences in the human immunodeficiency virus database indicated that the canonical 19b epitope is well conserved among isolates from the North American-European clade B and also among clade E isolates from Thailand and clade F isolates from Brazil. A minority of gp120s from clades A and C also possess the 19b epitope. Consistent with the theoretical predictions of its cross-clade reactivity, 19b was found to bind to gp120s from clades A, B, C, E, and F in immunoassays. However, 19b was not able to reduce the infectivity of primary viruses from clades A, E, and F that were predicted to possess the 19b epitope and only modestly reduced the infectivity of a clade C virus at low input virus concentrations. Cross-clade neutralization via V3-directed antibodies may, therefore, be difficult, even if the antibodies show broad reactivities in binding assays and the viruses theoretically possess the relevant binding site.
Collapse
Affiliation(s)
- J P Moore
- Aaron Diamond AIDS Research Center, New York University School of Medicine, New York 10016
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Stamatatos L, Werner A, Cheng-Mayer C. Differential regulation of cellular tropism and sensitivity to soluble CD4 neutralization by the envelope gp120 of human immunodeficiency virus type 1. J Virol 1994; 68:4973-9. [PMID: 8035496 PMCID: PMC236438 DOI: 10.1128/jvi.68.8.4973-4979.1994] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Using recombinant and mutant viruses generated between two human immunodeficiency virus type 1 isolates that display differences in cell tropism and sensitivity to soluble CD4 neutralization, we show that these two properties of the virus are regulated by different mechanisms. Whereas there is an association between V3 loop conformation and a particular cellular tropism, soluble CD4 neutralization sensitivity appears to be determined by amino acid differences in the C2 domain of the envelope gp120 that modulate the stability of gp120-gp41 association. Our findings further illustrate the importance of functional interactions among different regions of the envelope gp120 in regulating the biological phenotypes of human immunodeficiency virus and suggest that additional probing of the V3 loop with monoclonal antibodies may identify specific structural features of this loop that determine cell tropism.
Collapse
Affiliation(s)
- L Stamatatos
- Cancer Research Institute, School of Medicine, University of California, San Francisco 94143-0128
| | | | | |
Collapse
|