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1
McKenna, Philip M., Roger J. Pomerantz, Bernhard Dietzschold, James P. McGettigan, and Matthias J. Schnell. "Covalently Linked Human Immunodeficiency Virus Type 1 gp120/gp41 Is Stably Anchored in Rhabdovirus Particles and Exposes Critical Neutralizing Epitopes." Journal of Virology 77, no. 23 (December 1, 2003): 12782–94. http://dx.doi.org/10.1128/jvi.77.23.12782-12794.2003.
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ABSTRACT Rabies virus (RV) vaccine strain-based vectors show significant promise as potential live-attenuated vaccines against human immunodeficiency virus type 1 (HIV-1). Here we describe a new RV construct that will also likely have applications as a live-attenuated or killed-particle immunogen. We have created a RV containing a chimeric HIV-1 Env protein, which contains introduced cysteine residues that give rise to an intermolecular disulfide bridge between gp120 and the ectodomain of gp41. This covalently linked gp140 (gp140 SOS) is fused in frame to the cytoplasmic domain of RV G glycoprotein and is efficiently incorporated into the RV virion. On the HIV-1 virion, the gp120 and gp41 moieties are noncovalently associated, which leads to extensive shedding of gp120 from virions and virus-infected cells. The ability to use HIV-1 particles as purified, inactivated immunogens has been confounded by the loss of gp120 during preparation. Additionally, monomeric gp120 and uncleaved gp160 molecules have been shown to be poor antigenic representations of virion-associated gp160. Because the gp120 and gp41 portions are covalently attached in the gp140 SOS molecule, the protein is maintained on the surface of the RV virion throughout purification. Surface immunostaining and fluorescence-activated cell sorting analysis with anti-envelope antibodies show that the gp140 SOS protein is stably expressed on the surface of infected cells and maintains CD4 binding capabilities. Furthermore, Western blot and immunoprecipitation experiments with infected-cell lysates and purified virions show that a panel of neutralizing anti-envelope antibodies efficiently recognize the gp140 SOS protein. The antigenic properties of this recombinant RV particle containing covalently attached Env, as well as the ability to present Env in a membrane-bound form, suggest that this approach could be a useful component of a HIV-1 vaccine strategy.
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Binley, James M., Rogier W. Sanders, Brian Clas, Norbert Schuelke, Aditi Master, Yong Guo, Francis Kajumo, et al. "A Recombinant Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Complex Stabilized by an Intermolecular Disulfide Bond between the gp120 and gp41 Subunits Is an Antigenic Mimic of the Trimeric Virion-Associated Structure." Journal of Virology 74, no. 2 (January 15, 2000): 627–43. http://dx.doi.org/10.1128/jvi.74.2.627-643.2000.
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ABSTRACT The few antibodies that can potently neutralize human immunodeficiency virus type 1 (HIV-1) recognize the limited number of envelope glycoprotein epitopes exposed on infectious virions. These native envelope glycoprotein complexes comprise three gp120 subunits noncovalently and weakly associated with three gp41 moieties. The individual subunits induce neutralizing antibodies inefficiently but raise many nonneutralizing antibodies. Consequently, recombinant envelope glycoproteins do not elicit strong antiviral antibody responses, particularly against primary HIV-1 isolates. To try to develop recombinant proteins that are better antigenic mimics of the native envelope glycoprotein complex, we have introduced a disulfide bond between the C-terminal region of gp120 and the immunodominant segment of the gp41 ectodomain. The resulting gp140 protein is processed efficiently, producing a properly folded envelope glycoprotein complex. The association of gp120 with gp41 is now stabilized by the supplementary intermolecular disulfide bond, which forms with approximately 50% efficiency. The gp140 protein has antigenic properties which resemble those of the virion-associated complex. This type of gp140 protein may be worth evaluating for immunogenicity as a component of a multivalent HIV-1 vaccine.
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Khattar, Sunil K., Anthony L. DeVico, Celia C. LaBranche, Aruna Panda, David C. Montefiori, and Siba K. Samal. "Enhanced Immune Responses to HIV-1 Envelope Elicited by a Vaccine Regimen Consisting of Priming with Newcastle Disease Virus Expressing HIV gp160 and Boosting with gp120 and SOSIP gp140 Proteins." Journal of Virology 90, no. 3 (November 18, 2015): 1682–86. http://dx.doi.org/10.1128/jvi.02847-15.
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Newcastle disease virus (NDV) expressing HIV-1 BaL gp160 was evaluated either alone or with monomeric BaL gp120 and BaL SOSIP gp140 protein in a prime-boost combination in guinea pigs to enhance envelope (Env)-specific humoral and mucosal immune responses. We showed that a regimen consisting of an NDV prime followed by a protein boost elicited stronger serum and mucosal Th-1-biased IgG responses and neutralizing antibody responses than NDV-only immunizations. Additionally, these responses were higher after the gp120 than after the SOSIP gp140 protein boost.
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Klinman, D. M., K. W. Higgins, and J. Conover. "Sequential immunizations with rgp120s from independent isolates of human immunodeficiency virus type 1 induce the preferential expansion of broadly crossreactive B cells." Journal of Experimental Medicine 173, no. 4 (April 1, 1991): 881–87. http://dx.doi.org/10.1084/jem.173.4.881.
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The gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) is a dominant target against which the host's humoral immune response is directed. Unfortunately, gp120 proteins from different isolates of HIV are antigenically distinct, complicating the use of the envelope glycoprotein in vaccines designed to prevent acquired immunodeficiency syndrome. Using an enzyme-linked immunosorbent spot assay (ELISA), BALB/c mice immunized and boosted with recombinant purified gp120 were studied at the single cell level for their humoral immune response to HIV-1 envelope proteins. Approximately 90% of responding B cells produced antibodies reactive with the immunizing form of gp120 but not with gp120s from other strains of HIV. A novel sandwich ELISA was then used to analyze the frequency with which individual in vivo activated B cells produced antibodies that crossreacted with heterologous gp120s. Repeated immunizations with a single gp120 or with a mixture of different gp120s resulted in the activation of primarily mono-specific (noncrossreactive) B cells. In contrast, the sequential immunization of mice with recombinant purified envelope proteins from different strains of HIV (IIIB, SF2, and Zr6) induced the selective expansion of B cells producing highly crossreactive antibodies.
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Beddows, Simon, Norbert Schülke, Marc Kirschner, Kelly Barnes, Michael Franti, Elizabeth Michael, Thomas Ketas, et al. "Evaluating the Immunogenicity of a Disulfide-Stabilized, Cleaved, Trimeric Form of the Envelope Glycoprotein Complex of Human Immunodeficiency Virus Type 1." Journal of Virology 79, no. 14 (July 2005): 8812–27. http://dx.doi.org/10.1128/jvi.79.14.8812-8827.2005.
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ABSTRACT The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) complex comprises three gp120 exterior glycoproteins each noncovalently linked to a gp41 transmembrane glycoprotein. Monomeric gp120 proteins can elicit antibodies capable of neutralizing atypically sensitive test viruses in vitro, but these antibodies are ineffective against representative primary isolates and the gp120 vaccines failed to provide protection against HIV-1 transmission in vivo. Alternative approaches to raising neutralizing antibodies are therefore being pursued. Here we report on the antibody responses generated in rabbits against a soluble, cleaved, trimeric form of HIV-1JR-FL Env. In this construct, the gp120 and gp41 moieties are covalently linked by an intermolecular disulfide bond (SOS gp140), and an I559P substitution has been added to stabilize gp41-gp41 interactions (SOSIP gp140). We investigated the value of DNA priming and compared the use of membrane-bound and soluble priming antigens and of repeat boosting with soluble and particulate protein antigen. Compared to monomeric gp120, SOSIP gp140 trimers elicited approximately threefold lower titers of anti-gp120 antibodies. Priming with DNA encoding a membrane-bound form of the SOS gp140 protein, followed by several immunizations with soluble SOSIP gp140 trimers, resulted in antibodies capable of neutralizing sensitive strains at high titers. A subset of these sera also neutralized, at lower titers, HIV-1JR-FL and some other primary isolates in pseudovirus and/or whole-virus assays. Neutralization of these viruses was immunoglobulin mediated and was predominantly caused by antibodies to gp120 epitopes, but not the V3 region.
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Schülke, Norbert, Mika S. Vesanen, Rogier W. Sanders, Ping Zhu, Min Lu, Deborah J. Anselma, Anthony R. Villa, et al. "Oligomeric and Conformational Properties of a Proteolytically Mature, Disulfide-Stabilized Human Immunodeficiency Virus Type 1 gp140 Envelope Glycoprotein." Journal of Virology 76, no. 15 (August 1, 2002): 7760–76. http://dx.doi.org/10.1128/jvi.76.15.7760-7776.2002.
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ABSTRACT We describe the further properties of a protein, designated SOS gp140, wherein the association of the gp120 and gp41 subunits of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein is stabilized by an intersubunit disulfide bond. HIV-1JR-FL SOS gp140, proteolytically uncleaved gp140 (gp140UNC), and gp120 were expressed in stably transfected Chinese hamster ovary cells and analyzed for antigenic and structural properties before and after purification. Compared with gp140UNC, SOS gp140 reacted more strongly in surface plasmon resonance and radioimmunoprecipitation assays with the neutralizing monoclonal antibodies (MAbs) 2G12 (anti-gp120), 2F5 (anti-gp41), and 17b (to a CD4-induced epitope that overlaps the CCR5-binding site). In contrast, gp140UNC displayed the greater reactivity with nonneutralizing anti-gp120 and anti-gp41 MAbs. Immunoelectron microscopy studies suggested a model for SOS gp140 wherein the gp41 ectodomain (gp41ECTO) occludes the “nonneutralizing” face of gp120, consistent with the antigenic properties of this protein. We also report the application of Blue Native polyacrylamide gel electrophoresis (BN-PAGE), a high-resolution molecular sizing method, to the study of viral envelope proteins. BN-PAGE and other biophysical studies demonstrated that SOS gp140 was monomeric, whereas gp140UNC comprised a mixture of noncovalently associated and disulfide-linked dimers, trimers, and tetramers. The oligomeric and conformational properties of SOS gp140 and gp140UNC were largely unaffected by purification. An uncleaved gp140 protein containing the SOS cysteine mutations (SOS gp140UNC) was also oligomeric. Surprisingly, variable-loop-deleted SOS gp140 proteins were expressed (although not yet purified) as cleaved, noncovalently associated oligomers that were significantly more stable than the full-length protein. Overall, our findings have relevance for rational vaccine design.
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Christina Nilofer and Arumugam Mohanapriya. "Insights from the interfaces of HIV-1 envelope (ENV) trimer viral protein GP160 (GP120-GP41)." International Journal of Research in Pharmaceutical Sciences 12, no. 1 (January 6, 2021): 513–22. http://dx.doi.org/10.26452/ijrps.v12i1.4111.
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The Human Immunodeficiency Virus (HIV-1) type 1 viral protein is a life threatening virus causing HIV/AIDS in infected humans. The HIV-1 envelope (ENV) trimer glycoprotein GP160 (GP120-GP41) is gaining attention in recent years as a potential vaccine candidate for HIV-1/AIDS. However, the sequence variation and charge polarity at the interacting sites across clades is a shortcoming faced in the development of an effective HIV-1 vaccine. We analyzed the interfaces in terms of its interface area, interface size, and interface energies (van der Waals, hydrogen bonds, and electrostatics). The interfaces were divided as dominant (≥60%) and subdominant (<60%) based on van der Waals contribution to total energies. 88% of GP120 and 74% of GP41 interfaces are highly pronounced with van der Waals energy having large interfaces with interface size (98±65 (GP120) and 73±65 (GP41)) and interface area (882±1166Å2 (GP120) and 921±1288Å2 (GP41)). Nevertheless, 12% of GP120 and 26% of GP41 interfaces have subdominant van der Waals energies having small interfaces with interface size (58±20 (GP120) and 27±9 (GP41)) and interface area (581±1605Å2 (GP120) and 483±896Å2 (GP41)). It was interesting to observe GP41 small interfaces with subdominant van der Waals are stabilized by electrostatics (r2=0.63) without hydrogen bonds (r2=0). However, GP120 small interfaces were found to have two fold more hydrogen bonds (r2=0.59) than electrostatics (r2=0.20). Therefore, our previous finding stating that small protein-protein interfaces rich in electrostatics holds true in case of GP41 whereas not with GP120 protein interfaces.
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Stansell, Elizabeth, and Ronald C. Desrosiers. "Fundamental Difference in the Content of High-Mannose Carbohydrate in the HIV-1 and HIV-2 Lineages." Journal of Virology 84, no. 18 (July 7, 2010): 8998–9009. http://dx.doi.org/10.1128/jvi.00996-10.
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ABSTRACT The virus-encoded envelope proteins of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) typically contain 26 to 30 sites for N-linked carbohydrate attachment. N-linked carbohydrate can be of three major types: high mannose, complex, or hybrid. The lectin proteins from Galanthus nivalis (GNA) and Hippeastrum hybrid (HHA), which specifically bind high-mannose carbohydrate, were found to potently inhibit the replication of a pathogenic cloned SIV from rhesus macaques, SIVmac239. Passage of SIVmac239 in the presence of escalating concentrations of GNA and HHA yielded a lectin-resistant virus population that uniformly eliminated three sites (of 26 total) for N-linked carbohydrate attachment (Asn-X-Ser or Asn-X-Thr) in the envelope protein. Two of these sites were in the gp120 surface subunit of the envelope protein (Asn244 and Asn460), and one site was in the envelope gp41 transmembrane protein (Asn625). Maximal resistance to GNA and HHA in a spreading infection was conferred to cloned variants that lacked all three sites in combination. Variant SIV gp120s exhibited dramatically decreased capacity for binding GNA compared to SIVmac239 gp120 in an enzyme-linked immunosorbent assay (ELISA). Purified gp120s from six independent HIV type 1 (HIV-1) isolates and two SIV isolates from chimpanzees (SIVcpz) consistently bound GNA in ELISA at 3- to 10-fold-higher levels than gp120s from five SIV isolates from rhesus macaques or sooty mangabeys (SIVmac/sm) and four HIV-2 isolates. Thus, our data indicate that characteristic high-mannose carbohydrate contents have been retained in the cross-species transmission lineages for SIVcpz-HIV-1 (high), SIVsm-SIVmac (low), and SIVsm-HIV-2 (low).
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Balasubramanian, Anuradha, Ramesh K. Ganju, and Jerome E. Groopman. "HCV and HIV Envelope Proteins Co-Operatively Induce Fas-Mediated Apoptosis Via a Novel Stat1 Signaling Pathway." Blood 104, no. 11 (November 16, 2004): 604. http://dx.doi.org/10.1182/blood.v104.11.604.604.
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Abstract Hepatitis C virus (HCV) co-infects approximately 40% of patients with human immunodeficiency virus (HIV). HCV/HIV co-infected patients often have progressive liver disease that can lead to cirrhosis and death. We observed that hepatocytes exposed to HCV and HIV envelope proteins undergo apoptosis via an ‘innocent bystander’ mechanism due to cell surface binding of viral proteins independent of direct viral infection. HCV envelope protein E2 (1.5 nM) and HIV envelope protein gp120 (0.8 nM) derived from M-tropic and T-tropic viruses induce significant apoptosis in both hepatocytic cell lines and primary hepatocytes, while either of these viral proteins alone does not. Now, we have elucidated the signaling mechanisms that mediate this effect. HCV-E2 and HIV-gp120 were found to significantly upregulate Fas ligand (FasL). We then examined the Stat family of proteins known to participate in FasL and apoptotic pathways. We observed an increased DNA binding activity of Stat1 upon HCV-E2 and HIV-gp120 stimulation. Furthermore, overexpression of wild type Stat1αincreased apoptosis and FasL expression in HepG2 cells, whereas a C-terminal domain deleted mutant, Stat1β, decreased HCV-E2 and HIV-gp120 mediated apoptosis and FasL upregulation. Overexpression of Stat1αand Stat1β in primary hepatocytes confirmed that Stat1αenhanced apoptosis upon HCV-E2 and HIV-gp120 treatment. We observed a tyrosine dependent activation of Stat1 and a subsequent serine phosphorylation of Stat1. TYK2, lyn kinase, RAFTK and MAP kinases were activated upstream of Stat1. In addition, Stat1 associated with the death domain-containing adapter protein TRADD. TRADD is known to induce inflammatory signaling through the NFκB pathway. Here, the association of Stat1 with TRADD would reduce the availability of TRADD to induce NFκB. Thus, Stat1 sequestration of downstream apoptotic signaling molecules would block the host inflammatory response. Further characterization of Fas-mediated apoptosis revealed that caspase 3 and caspase 7 were activated following HCV-E2 and HIV-gp120 stimulation. However, we were not able to detect significant activity of either caspase 8 or caspase 9. We also found a loss in mitochondrial membrane potential upon HCV-E2 and HIV-gp120 stimulation, which leads to the release of cytochrome C and AIF into the cytosol. Taken together, these studies indicate that the viral proteins of HCV and HIV co-operate in causing the apoptosis of hepatocytes, independent of direct infection, by induction of novel Stat1 downstream signaling pathways at the expense of a normal host inflammatory response.
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Anand, Appakkudal R., Anil Prasad, Ritu R. Bradley, Yadwinder S. Deol, Tirumuru Nagaraja, Xianghui Ren, Ernest F. Terwilliger, and Ramesh K. Ganju. "HIV-1 gp120-induced migration of dendritic cells is regulated by a novel kinase cascade involving Pyk2, p38 MAP kinase, and LSP1." Blood 114, no. 17 (October 22, 2009): 3588–600. http://dx.doi.org/10.1182/blood-2009-02-206342.
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AbstractTargeting dendritic cell (DC) functions such as migration is a pivotal mechanism used by HIV-1 to disseminate within the host. The HIV-1 envelope protein is the most important of the virally encoded proteins that exploits the migratory capacity of DCs. In the present study, we elucidated the signaling machinery involved in migration of immature DCs (iDCs) in response to HIV-1 envelope protein. We observed that M-tropic HIV-1 glycoprotein 120 (gp120) induces phosphorylation of the nonreceptor tyrosine kinase, Pyk2. Inhibition of Pyk2 activity using a pharmacologic inhibitor, kinase-inactive Pyk2 mutant, and Pyk2-specific small interfering RNA blocked gp120-induced chemotaxis, confirming the role of Pyk2 in iDC migration. In addition, we also illustrated the importance of Pyk2 in iDC migration induced by virion-associated envelope protein, using aldithriol-2–inactivated M-tropic HIV-1 virus. Further analysis of the downstream signaling mechanisms involved in gp120-induced migration revealed that Pyk2 activates p38 mitogen-activated protein kinase, which in turn activates the F-actin–binding protein, leukocyte-specific protein 1, and enhances its association with actin. Taken together, our studies provide an insight into a novel gp120-mediated pathway that regulates DC chemotaxis and contributes to the dissemination of HIV-1 within an infected person.
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Yang, Xinzhen, Juliette Lee, Erin M. Mahony, Peter D. Kwong, Richard Wyatt, and Joseph Sodroski. "Highly Stable Trimers Formed by Human Immunodeficiency Virus Type 1 Envelope Glycoproteins Fused with the Trimeric Motif of T4 Bacteriophage Fibritin." Journal of Virology 76, no. 9 (May 1, 2002): 4634–42. http://dx.doi.org/10.1128/jvi.76.9.4634-4642.2002.
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ABSTRACT The envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) function as a trimer composed of three gp120 exterior glycoproteins and three gp41 transmembrane proteins. Soluble gp140 glycoproteins composed of the uncleaved ectodomains of gp120 and gp41 form unstable, heterogeneous oligomers, but soluble gp140 trimers can be stabilized by fusion with a C-terminal, trimeric GCN4 motif (X. Yang et al., J. Virol. 74:5716-5725, 2000). To understand the influence of the C-terminal trimerization domain on the properties of soluble HIV-1 envelope glycoprotein trimers, uncleaved, soluble gp140 glycoproteins were stabilized by fusion with another trimeric motif derived from T4 bacteriophage fibritin. The fibritin construct was more stable to heat and reducing conditions than the GCN4 construct. Both GCN4- and fibritin-stabilized soluble gp140 glycoproteins exhibited patterns of neutralizing and nonneutralizing antibody binding expected for the functional envelope glycoprotein spike. Of note, two potently neutralizing antibodies, immunoglobulin G1b12 and 2G12, exhibited the greatest recognition of the stabilized, soluble trimers, relative to recognition of the gp120 monomer. The observed similarities between the GCN4 and fibritin constructs indicate that the HIV-1 envelope glycoprotein ectodomains dictate many of the antigenic and structural features of these fusion proteins. The melting temperatures and ligand recognition properties of the GCN4- and fibritin-stabilized soluble gp140 glycoproteins suggest that these molecules assume conformations distinct from that of the fusion-active, six-helix bundle.
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Meschi, Joseph, Erika C. Crouch, Paul Skolnik, Khabirah Yahya, Uffe Holmskov, Rikke Leth-Larsen, Ida Tornoe, Tesfaldet Tecle, Mitchell R. White, and Kevan L. Hartshorn. "Surfactant protein D binds to human immunodeficiency virus (HIV) envelope protein gp120 and inhibits HIV replication." Journal of General Virology 86, no. 11 (November 1, 2005): 3097–107. http://dx.doi.org/10.1099/vir.0.80764-0.
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The envelope protein (gp120) of human immunodeficiency virus (HIV) contains highly conserved mannosylated oligosaccharides. These glycoconjugates contribute to resistance to antibody neutralization, and binding to cell surface lectins on macrophages and dendritic cells. Mannose-binding lectin (MBL) binds to gp120 and plays a role in defence against the virus. In this study it is demonstrated that surfactant protein D (SP-D) binds to gp120 and inhibits HIV infectivity at significantly lower concentrations than MBL. The binding of SP-D was mediated by its calcium-dependent carbohydrate-binding activity and was dependent on glycosylation of gp120. Native dodecameric SP-D bound to HIV gp120 more strongly than native trimeric SP-D. Since one common polymorphic form of SP-D is predominantly expressed as trimers and associated with lower blood levels, these individuals may have less effective innate defence against HIV. A chimeric protein containing the N-terminal and collagen domains of SP-D linked to the neck and carbohydrate-recognition domains of MBL (called SP-D/MBLneck+CRD) had greater ability to bind to gp120 and inhibit virus replication than either SP-D or MBL. The enhanced binding of SP-D/MBLneck+CRD was dependent on assembly into higher molecular mass multimers (i.e. a trimeric form of the chimera did not bind to a greater extent than MBL). Hence, the enhanced binding of SP-D compared with MBL results from distinctive properties of its N-terminal and/or collagen domains. SP-D is present in lung and airway fluids, as well as in blood and various mucosal locations, and could, like MBL, play a role in restricting HIV transmission or replication in vivo.
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Earl, Patricia L., Wataru Sugiura, David C. Montefiori, Christopher C. Broder, Susan A. Lee, Carl Wild, Jeffrey Lifson, and Bernard Moss. "Immunogenicity and Protective Efficacy of Oligomeric Human Immunodeficiency Virus Type 1 gp140." Journal of Virology 75, no. 2 (January 15, 2001): 645–53. http://dx.doi.org/10.1128/jvi.75.2.645-653.2001.
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ABSTRACT The biologically active form of the human immunodeficiency virus type 1 (HIV-1) envelope (Env) glycoprotein is oligomeric. We previously described a soluble HIV-1 IIIB Env protein, gp140, with a stable oligomeric structure composed of uncleaved gp120 linked to the ectodomain of gp41 (P. L. Earl, C. C. Broder, D. Long, S. A. Lee, J. Peterson, S. Chakrabarti, R. W. Doms, and B. Moss, J. Virol. 68:3015–3026, 1994). Here we compared the antibody responses of rabbits to gp120 and gp140 that had been produced and purified in an identical manner. The gp140 antisera exhibited enhanced cross-reactivity with heterologous Env proteins as well as greater neutralization of HIV-1 compared to the gp120 antisera. To examine both immunogenicity and protective efficacy, we immunized rhesus macaques with oligomeric gp140. Strong neutralizing antibodies against a homologous virus and modest neutralization of heterologous laboratory-adapted isolates were elicited. No neutralization of primary isolates was observed. However, a substantial fraction of the neutralizing activity could not be blocked by a V3 loop peptide. After intravenous challenge with simian-HIV virus SHIV-HXB2, three of the four vaccinated macaques exhibited no evidence of virus replication.
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Yolitz, Jason, Catherine Schwing, Julia Chang, Donald Van Ryk, Fatima Nawaz, Danlan Wei, Claudia Cicala, James Arthos, and Anthony S. Fauci. "Signal peptide of HIV envelope protein impacts glycosylation and antigenicity of gp120." Proceedings of the National Academy of Sciences 115, no. 10 (February 20, 2018): 2443–48. http://dx.doi.org/10.1073/pnas.1722627115.
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The HIV-1 envelope protein (Env) of early-replicating viruses encodes several distinct transmission signatures. One such signature involves a reduced number of potential N-linked glycosylation sites (PNGs). This transmission signature underscores the importance of posttranslational modifications in the fitness of early-replicating isolates. An additional signature in Env involves the overrepresentation of basic amino acid residues at a specific position in the Env signal peptide (SP). In this report, we investigated the potential impact of this SP signature on gp120 glycosylation and antigenicity. Two recombinant gp120s were constructed, one derived from an isolate that lacks this signature and a second from an early-replicating isolate that includes this signature. Chimeric gp120s were also constructed in which the two SPs were swapped between the isolates. All four gp120s were probed with glycan-, structure- and receptor- specific probes in a surface plasmon resonance binding assay. We found that the SP of Env influences qualitative aspects of Env glycosylation that in turn affect the antigenicity of Env in a major way. The SP impacts the affinity of Env for DC-SIGN, a lectin receptor expressed on dendritic cells that is believed to play a role in mucosal transmission. Additionally, affinity for the monoclonal antibodies 17b and A32, which recognize a CD4-induced, open conformation of Env is also altered. These results demonstrate that natural variation in the SP of HIV Env can significantly impact the antigenicity of mature gp120. Thus, the SP is likely subject to antibody-mediated immune pressure.
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Pritchard, Laura K., David J. Harvey, Camille Bonomelli, Max Crispin, and Katie J. Doores. "Cell- and Protein-Directed Glycosylation of Native Cleaved HIV-1 Envelope." Journal of Virology 89, no. 17 (June 17, 2015): 8932–44. http://dx.doi.org/10.1128/jvi.01190-15.
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ABSTRACTThe gp120/gp41 HIV-1 envelope glycoprotein (Env) is highly glycosylated, with up to 50% of its mass consisting ofN-linked glycans. This dense carbohydrate coat has emerged as a promising vaccine target, with its glycans acting as epitopes for a number of potent and broadly neutralizing antibodies (bnAbs). Characterizing the glycan structures present on native HIV-1 Env is thus a critical goal for the design of Env immunogens. In this study, we used a complementary, multistep approach involving ion mobility mass spectrometry and high-performance liquid chromatography to comprehensively characterize the glycan structures present on HIV-1 gp120 produced in peripheral blood mononuclear cells (PBMCs). The capacity of different expression systems, including pseudoviral particles and recombinant cell surface trimers, to reproduce native-like glycosylation was then assessed. A population of oligomannose glycans on gp120 was reproduced across all expression systems, supporting this as an intrinsic property of Env that can be targeted for vaccine design. In contrast, Env produced in HEK 293T cells failed to accurately reproduce the highly processed complex-type glycan structures observed on PBMC-derived gp120, and in particular the precise linkage of sialic acid residues that cap these glycans. Finally, we show that unlike for gp120, the glycans decorating gp41 are mostly complex-type sugars, consistent with the glycan specificity of bnAbs that target this region. These findings provide insights into the glycosylation of native and recombinant HIV-1 Env and can be used to inform strategies for immunogen design and preparation.IMPORTANCEDevelopment of an HIV vaccine is desperately needed to control new infections, and elicitation of HIV bnAbs will likely be an important component of an effective vaccine. Increasingly, HIV bnAbs are being identified that bind to theN-linked glycans coating the HIV envelope glycoproteins gp120 and gp41, highlighting them as important targets for vaccine design. It is therefore important to characterize the glycan structures present on native, virion-associated gp120 and gp41 for development of vaccines that accurately mimic native-Env glycosylation. In this study, we used a number of analytical techniques to precisely study the structures of both the oligomannose and complex-type glycans present on native Env to provide a reference for determining the ability of potential HIV immunogens to accurately replicate the glycosylation pattern on these native structures.
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Kant, Sanket, Ningyu Zhang, Jean-Pierre Routy, Cécile Tremblay, Réjean Thomas, Jason Szabo, Pierre Côté, et al. "Quantifying Anti-HIV Envelope-Specific Antibodies in Plasma from HIV Infected Individuals." Viruses 11, no. 6 (May 28, 2019): 487. http://dx.doi.org/10.3390/v11060487.
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Quantifying HIV Envelope (Env)-specific antibodies in HIV+ plasma is useful for interpreting antibody dependent cellular cytotoxicity assay results. HIV Env, the only viral protein expressed on the surface of infected cells, has a native trimeric closed conformation on cells infected with wild-type HIV. However, CD4+ uninfected bystander cells in HIV+ cell cultures bind gp120 shed from HIV+ cells exposing CD4-induced epitopes normally hidden in native Env. We used flow-cytometry based assays to quantify antibodies in HIV+ plasma specific for native trimeric Env or gp120/CD4 conjugates using CEM.NKr.CCR5 (CEM) cells infected with HIV (iCEM) or coated with recombinant gp120 (cCEM), as a surrogate for gp120+ HIV- bystander cells. Results from both assays were compared to those of a plate-based ELISA to monomeric gp120. The levels of Env-specific antibodies to cCEM and iCEM, measured by flow cytometry, and to gp120 by ELISA were positively correlated. More antibodies in HIV+ plasma recognized the gp120 conformation exposed on cCEM than on iCEM. Comparisons of plasma from untreated progressors, treated progressors, and elite controllers revealed that antibodies to Env epitopes were the lowest in treated progressors. Plasma from elite controllers and untreated progressors had similarly high levels of Env-specific antibodies, despite elite controllers having undetectable HIV viral loads, while untreated progressors maintained high viral loads.
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Lin, P. F., H. Samanta, C. M. Bechtold, C. A. Deminie, A. K. Patick, M. Alam, K. Riccardi, R. E. Rose, R. J. White, and R. J. Colonno. "Characterization of siamycin I, a human immunodeficiency virus fusion inhibitor." Antimicrobial Agents and Chemotherapy 40, no. 1 (January 1996): 133–38. http://dx.doi.org/10.1128/aac.40.1.133.
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The human immunodeficiency virus (HIV) fusion inhibitor siamycin I, a 21-residue tricyclic peptide, was identified from a Streptomyces culture by using a cell fusion assay involving cocultivation of HeLa-CD4+ cells and monkey kidney (BSC-1) cells expressing the HIV envelope gp160. Siamycin I is effective against acute HIV type 1 (HIV-1) and HIV-2 infections, with 50% effective doses ranging from 0.05 to 5.7 microM, and the concentration resulting in a 50% decrease in cell viability in the absence of viral infection is 150 microM in CEM-SS cells. Siamycin I inhibits fusion between C8166 cells and CEM-SS cells chronically infected with HIV (50% effective dose of 0.08 microM) but has no effect on Sendai virus-induced fusion or murine myoblast fusion. Siamycin I does not inhibit gp120 binding to CD4 in either gp120- or CD4-based capture enzyme-linked immunosorbent assays. Inhibition of HIV-induced fusion by this compound is reversible, suggesting that siamycin I binds noncovalently. An HIV-1 resistant variant was selected by in vitro passage of virus in the presence of increasing concentrations of siamycin I. Drug susceptibility studies on a chimeric virus containing the envelope gene from the siamycin I-resistant variant indicate that resistance maps to the gp160 gene. Envelope-deficient HIV complemented with gp160 from siamycin I-resistant HIV also displayed a resistant phenotype upon infection of HeLa-CD4-LTR-beta-gal cells. A comparison of the DNA sequences of the envelope genes from the resistant and parent viruses revealed a total of six amino acid changes. Together these results indicate that siamycin I interacts with the HIV envelope protein.
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Dey, Barna, Danica L. Lerner, Paolo Lusso, Michael R. Boyd, John H. Elder, and Edward A. Berger. "Multiple Antiviral Activities of Cyanovirin-N: Blocking of Human Immunodeficiency Virus Type 1 gp120 Interaction with CD4 and Coreceptor and Inhibition of Diverse Enveloped Viruses." Journal of Virology 74, no. 10 (May 15, 2000): 4562–69. http://dx.doi.org/10.1128/jvi.74.10.4562-4569.2000.
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ABSTRACT Cyanovirin-N (CV-N) is a cyanobacterial protein with potent neutralizing activity against human immunodeficiency virus (HIV). CV-N has been shown to bind HIV type 1 (HIV-1) gp120 with high affinity; moreover, it blocks the envelope glycoprotein-mediated membrane fusion reaction associated with HIV-1 entry. However, the inhibitory mechanism(s) remains unclear. In this study, we show that CV-N blocked binding of gp120 to cell-associated CD4. Consistent with this, pretreatment of gp120 with CV-N inhibited soluble CD4 (sCD4)-dependent binding of gp120 to cell-associated CCR5. To investigate possible effects of CV-N at post-CD4 binding steps, we used an assay that measures sCD4 activation of the HIV-1 envelope glycoprotein for fusion with CCR5-expressing cells. CV-N displayed equivalently potent inhibitory effects when added before or after sCD4 activation, suggesting that CV-N also has blocking action at the level of gp120 interaction with coreceptor. This effect was shown not to be due to CV-N-induced coreceptor down-modulation after the CD4 binding step. The multiple activities against the HIV-1 envelope glycoprotein prompted us to examine other enveloped viruses. CV-N potently blocked infection by feline immunodeficiency virus, which utilizes the chemokine receptor CXCR4 as an entry receptor but is CD4 independent. CV-N also inhibited fusion and/or infection by human herpesvirus 6 and measles virus but not by vaccinia virus. Thus, CV-N has broad-spectrum antiviral activity, both for multiple steps in the HIV entry mechanism and for diverse enveloped viruses. This broad specificity has implications for potential clinical utility of CV-N.
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Stamatos, Nicholas M., John R. Mascola, Vaniambadi S. Kalyanaraman, Mark K. Louder, Lynn M. Frampton, Deborah L. Birx, and Thomas C. VanCott. "Neutralizing Antibodies from the Sera of Human Immunodeficiency Virus Type 1-Infected Individuals Bind to Monomeric gp120 and Oligomeric gp140." Journal of Virology 72, no. 12 (December 1, 1998): 9656–67. http://dx.doi.org/10.1128/jvi.72.12.9656-9667.1998.
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ABSTRACT Antibodies that neutralize primary isolates of human immunodeficiency virus type 1 (HIV-1) appear during HIV-1 infection but are difficult to elicit by immunization with current vaccine products comprised of monomeric forms of HIV-1 envelope glycoprotein gp120. The limited neutralizing antibody response generated by gp120 vaccine products could be due to the absence or inaccessibility of the relevant epitopes. To determine whether neutralizing antibodies from HIV-1-infected patients bind to epitopes accessible on monomeric gp120 and/or oligomeric gp140 (ogp140), purified total immunoglobulin from the sera of two HIV-1-infected patients as well as pooled HIV immune globulin were selectively depleted of antibodies which bound to immobilized gp120 or ogp140. After passage of each immunoglobulin preparation through the respective columns, antibody titers against gp120 and ogp140 were specifically reduced at least 128-fold. The gp120- and gp140-depleted antibody fraction from each serum displayed reduced neutralization activity against three primary and two T-cell line-adapted (TCLA) HIV-1 isolates. Significant residual neutralizing activity, however, persisted in the depleted sera, indicating additional neutralizing antibody specificities. gp120- and ogp140-specific antibodies eluted from each column neutralized both primary and TCLA viruses. These data demonstrate the presence and accessibility of epitopes on both monomeric gp120 and ogp140 that are specific for antibodies that are capable of neutralizing primary isolates of HIV-1. Thus, the difficulties associated with eliciting neutralizing antibodies by using current monomeric gp120 subunit vaccines may be related less to improper protein structure and more to ineffective immunogen formulation and/or presentation.
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Casini, Antonio, Michele Olivieri, Lara Vecchi, Oscar R. Burrone, and Anna Cereseto. "Reduction of HIV-1 Infectivity through Endoplasmic Reticulum-Associated Degradation-Mediated Env Depletion." Journal of Virology 89, no. 5 (December 24, 2014): 2966–71. http://dx.doi.org/10.1128/jvi.02634-14.
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During the HIV-1 replicative cycle, the gp160 envelope is processed in the secretory pathway to mature into the gp41 and gp120 subunits. Misfolded proteins located within the endoplasmic reticulum (ER) are proteasomally degraded through the ER-associated degradation (ERAD) pathway, a quality control system operating in this compartment. Here, we exploited the ERAD pathway to induce the degradation of gp160 during viral production, thus leading to the release of gp120-depleted viral particles.
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Yang, Xinzhen, Vesko Tomov, Svetla Kurteva, Liping Wang, Xinping Ren, Miroslaw K. Gorny, Susan Zolla-Pazner, and Joseph Sodroski. "Characterization of the Outer Domain of the gp120 Glycoprotein from Human Immunodeficiency Virus Type 1." Journal of Virology 78, no. 23 (December 1, 2004): 12975–86. http://dx.doi.org/10.1128/jvi.78.23.12975-12986.2004.
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ABSTRACT The core of the gp120 glycoprotein from human immunodeficiency virus type 1 (HIV-1) is comprised of three major structural domains: the outer domain, the inner domain, and the bridging sheet. The outer domain is exposed on the HIV-1 envelope glycoprotein trimer and contains binding surfaces for neutralizing antibodies such as 2G12, immunoglobulin G1b12, and anti-V3 antibodies. We expressed the outer domain of HIV-1YU2 gp120 as an independent protein, termed OD1. OD1 efficiently bound 2G12 and a large number of anti-V3 antibodies, indicating its structural integrity. Immunochemical studies with OD1 indicated that antibody responses against the outer domain of the HIV-1 gp120 envelope glycoprotein are rare in HIV-1-infected human sera that potently neutralize the virus. Surprisingly, such outer-domain-directed antibody responses are commonly elicited by immunization with recombinant monomeric gp120. Immunization with soluble, stabilized HIV-1 envelope glycoprotein trimers elicited antibody responses that more closely resembled those in the sera of HIV-1-infected individuals. These results underscore the qualitatively different humoral immune responses elicited during natural infection and after gp120 vaccination and help to explain the failure of gp120 as an effective vaccine.
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Ullrich, Christina K., Jerome E. Groopman, and Ramesh K. Ganju. "HIV-1 gp120- and gp160-induced apoptosis in cultured endothelial cells is mediated by caspases." Blood 96, no. 4 (August 15, 2000): 1438–42. http://dx.doi.org/10.1182/blood.v96.4.1438.
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Abstract The immune dysfunction and cell destruction that occur in the human immunodeficiency virus (HIV)-infected host appear to result from the direct cytopathic effects of viral infection and the effects of viral proteins on uninfected bystander cells. Recently, the α-chemokine receptor CXCR4 has been reported to mediate apoptosis in neuronal cells and in CD4+ and CD8+ T cells after its binding to HIV-1 envelope proteins. In the current study, it was observed that human umbilical vein endothelial cells (HUVEC) undergo apoptosis after their treatment with the HIV-1 envelope proteins gp120/160. Anti-CXCR4 monoclonal antibody decreased HIV-1 gp120/160-induced apoptosis, suggesting that the CXCR4 chemokine receptor mediates the apoptotic effects of these HIV envelope glycoproteins. Further studies revealed that caspases play an important role in this process because the pretreatment of cells with a general caspase enzyme inhibitor decreased the extent of HUVEC apoptosis induced by gp120/160. In addition, it was found that caspase-3 was activated on HIV-1 gp120/160 treatment of these cells. It was also observed that gp120/160 treatment slightly increased the expression of the pro-apoptotic molecule Bax. These results suggest that HIV-1 envelope glycoproteins can disrupt endothelial integrity through the interaction with CXCR4, thereby facilitating virus transit out of the bloodstream and contributing to the vascular injury syndromes seen in acquired immunodeficiency syndrome.
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Ullrich, Christina K., Jerome E. Groopman, and Ramesh K. Ganju. "HIV-1 gp120- and gp160-induced apoptosis in cultured endothelial cells is mediated by caspases." Blood 96, no. 4 (August 15, 2000): 1438–42. http://dx.doi.org/10.1182/blood.v96.4.1438.h8001438_1438_1442.
Full textAbstract:
The immune dysfunction and cell destruction that occur in the human immunodeficiency virus (HIV)-infected host appear to result from the direct cytopathic effects of viral infection and the effects of viral proteins on uninfected bystander cells. Recently, the α-chemokine receptor CXCR4 has been reported to mediate apoptosis in neuronal cells and in CD4+ and CD8+ T cells after its binding to HIV-1 envelope proteins. In the current study, it was observed that human umbilical vein endothelial cells (HUVEC) undergo apoptosis after their treatment with the HIV-1 envelope proteins gp120/160. Anti-CXCR4 monoclonal antibody decreased HIV-1 gp120/160-induced apoptosis, suggesting that the CXCR4 chemokine receptor mediates the apoptotic effects of these HIV envelope glycoproteins. Further studies revealed that caspases play an important role in this process because the pretreatment of cells with a general caspase enzyme inhibitor decreased the extent of HUVEC apoptosis induced by gp120/160. In addition, it was found that caspase-3 was activated on HIV-1 gp120/160 treatment of these cells. It was also observed that gp120/160 treatment slightly increased the expression of the pro-apoptotic molecule Bax. These results suggest that HIV-1 envelope glycoproteins can disrupt endothelial integrity through the interaction with CXCR4, thereby facilitating virus transit out of the bloodstream and contributing to the vascular injury syndromes seen in acquired immunodeficiency syndrome.
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Srivastava, Indresh K., Keating VanDorsten, Lucia Vojtech, Susan W. Barnett, and Leonidas Stamatatos. "Changes in the Immunogenic Properties of Soluble gp140 Human Immunodeficiency Virus Envelope Constructs upon Partial Deletion of the Second Hypervariable Region." Journal of Virology 77, no. 4 (February 15, 2003): 2310–20. http://dx.doi.org/10.1128/jvi.77.4.2310-2320.2003.
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ABSTRACT Immunization of macaques with the soluble oligomeric gp140 form of the SF162 envelope (SF162gp140) or with an SF162gp140-derived construct lacking the central region of the V2 loop (ΔV2gp140) results in the generation of high titers of antibodies capable of neutralizing the homologous human immunodeficiency virus type 1 (HIV-1), SF162 virus (Barnett et al. J. Virol. 75 :5526-5540, 2001). However, the ΔV2gp140 immunogen is more effective than the SF162gp140 immunogen in eliciting the generation of antibodies capable of neutralizing heterologous HIV-1 isolates. This indicates that deletion of the V2 loop alters the immunogenicity of the SF162gp140 protein. The present studies were aimed at identifying the envelope regions whose immunogenicity is altered following V2 loop deletion. We report that the antibodies elicited by the SF162gp140 immunogen recognize elements of the V1, V2, and V3 loops, the CD4-binding site, and the C1 and C2 regions on the homologous SF162 gp120. With the exception of the V1 and V2 loops, the same regions are recognized on heterologous gp120 proteins. Surprisingly, although a minority of the SF162gp140-elicited antibodies target the V3 loop on the homologous gp120, the majority of the antibodies elicited by this immunogen that are capable of binding to the heterologous gp120s tested recognize their V3 loops. Deletion of the V2 loop has two effects. First, it alters the immunogenicity of the V3 and V1 loops, and second, it renders the C5 region immunogenic. Although deletion of the V2 loop does not result in an increase in the immunogenicity of the CD4-binding site per se, the relative ratio of anti-CD4-binding site to anti-V3 loop antibodies that bind to the heterologous gp120s tested is higher in sera collected from the ΔV2gp140-immunized animals than in the SF162gp140-immunized animals. Overall, our studies indicate that it is possible to alter the immunogenic structure of the HIV envelope by introducing specific modifications.
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Tamma, Seetha M. Lakshmi, Narendra Chirmule, Hirosuka Yagura, Naoki Oyaizu, Vaniambadi Kalyanaraman, and Savita Pahwa. "CD4 Cross-Linking (CD4XL) Induces RAS Activation and Tumor Necrosis Factor-α Secretion in CD4+ T Cells." Blood 90, no. 4 (August 15, 1997): 1588–93. http://dx.doi.org/10.1182/blood.v90.4.1588.
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Abstract CD4 molecules are the primary receptors for human immunodeficiency virus (HIV) and bind the envelope glycoprotein gp120 of HIV with high-affinity. We have previously shown that cross-linking of CD4 molecules (CD4XL) in normal peripheral blood mononuclear cells (PBMC) results in secretion of cytokines tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), but not of interleukin-2 (IL-2) or IL-4. To investigate the intracellular signaling events associated with CD4-gp120 interaction, we incubated CD4+ T cells from peripheral blood of HIV-negative healthy donors with HIV envelope protein gp160 alone or performed CD4XL with gp160 and anti-gp160 antibody. This procedure resulted in tyrosine phosphorylation of intracellular substrates p59fyn, zap 70, and p95vav and also led to ras activation, as assessed by conversion of rasGDP to rasGTP. The role of ras in CD4 signaling was further investigated using CD4+ Jurkat cells transfected with a dominant negative ras mutant. CD4+ T cells expressing dn-ras secreted significantly reduced levels of TNF-α in response to CD4XL. These studies indicate that interaction of HIV gp160 with CD4 molecules activates the ras pathway in T cells, which may result in the cells becoming unresponsive to subsequent stimulation.
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Tamma, Seetha M. Lakshmi, Narendra Chirmule, Hirosuka Yagura, Naoki Oyaizu, Vaniambadi Kalyanaraman, and Savita Pahwa. "CD4 Cross-Linking (CD4XL) Induces RAS Activation and Tumor Necrosis Factor-α Secretion in CD4+ T Cells." Blood 90, no. 4 (August 15, 1997): 1588–93. http://dx.doi.org/10.1182/blood.v90.4.1588.1588_1588_1593.
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CD4 molecules are the primary receptors for human immunodeficiency virus (HIV) and bind the envelope glycoprotein gp120 of HIV with high-affinity. We have previously shown that cross-linking of CD4 molecules (CD4XL) in normal peripheral blood mononuclear cells (PBMC) results in secretion of cytokines tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), but not of interleukin-2 (IL-2) or IL-4. To investigate the intracellular signaling events associated with CD4-gp120 interaction, we incubated CD4+ T cells from peripheral blood of HIV-negative healthy donors with HIV envelope protein gp160 alone or performed CD4XL with gp160 and anti-gp160 antibody. This procedure resulted in tyrosine phosphorylation of intracellular substrates p59fyn, zap 70, and p95vav and also led to ras activation, as assessed by conversion of rasGDP to rasGTP. The role of ras in CD4 signaling was further investigated using CD4+ Jurkat cells transfected with a dominant negative ras mutant. CD4+ T cells expressing dn-ras secreted significantly reduced levels of TNF-α in response to CD4XL. These studies indicate that interaction of HIV gp160 with CD4 molecules activates the ras pathway in T cells, which may result in the cells becoming unresponsive to subsequent stimulation.
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Zhang, Xuefeng, Jian Feng Wang, and Jerome E. Groopman. "HIV Envelope Protein gp120 Stimulates Expression of Specific Chemokines in Lymphatic Endothelial Cells." Blood 104, no. 11 (November 16, 2004): 3102. http://dx.doi.org/10.1182/blood.v104.11.3102.3102.
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Abstract Lymphoid organs are the major anatomical home of HIV, where the virus replicates during both the acute and chronic phases of infections. In this regard, there are significantly more infected cells in lymph nodes (LNs) than in circulating blood, and these infected cells are a major reservoir of infectious HIV. Certain chemokines like CCL19 (MIP-3β) and CCL21 (SLC) play key roles in immune cell trafficking to LNs. They induce specific homing of naïve T cells and dendritic cells into the T cell zone of secondary lymphoid organs. There, the T cells become activated by the dendritic cells. A network of channels composed of lymphatic endothelium exists in LNs that provides a route for this dendritic cell and T cell movement. To date, how this lymphatic endothelium may contribute to the pathogenesis of HIV infection has not been studied. This prompted us to investigate whether HIV may alter immune cell trafficking via interaction with this lymphatic network. Lymphatic endothelial cells (LEC) were separated from primary dermal microvascular endothelial cells. The phenotype of LEC was confirmed by immunostaining with specific lymphatic markers including VEGFR-3, LYVE-1, and podoplanin. Since HIV envelope proteins are presented to endothelial cells in the microenvironment, we studied the effects of X4 gp120 on LEC. Using a pathway specific cDNA array, we detected enhanced expression of a restricted repertoire of chemokines in LEC upon HIV-1 gp120 stimulation. Gp120 upregulated expression of the chemokine genes GRO-α, GRO-γ, MIP-3β, and SDF-1α and β in LEC. These chemokines can act to enhance T cell and dendritic cell homing to LNs. Furthermore, we also detected GRO-α, SDF-1, and SLC proteins in culture supernatants of the gp120-treated LEC. We did not observe upregulation of the chemokines RANTES and MCP-1 upon gp120 stimulation. Since dendritic cells mediate the HIV infectivity of CD4+ T cells by presenting HIV particles, our study suggests that HIV-1 gp120-induced production of a restricted repertoire of chemokines in LEC may accelerate the trafficking of infected dendritic cells to LNs and foster HIV infection in this reservoir.
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Hirano, Makoto. "Glycoform-Dependent Antigenicity in gp120 of HIV-1 Envelope Protein." Trends in Glycoscience and Glycotechnology 26, no. 147 (2014): 29–32. http://dx.doi.org/10.4052/tigg.26.29.
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Haynes, B. F., L. O. Arthur, P. Frost, T. J. Matthews, A. J. Langlois, T. J. Palker, M. K. Hart, R. M. Scearce, D. M. Jones, and C. McDanal. "Conversion of an immunogenic human immunodeficiency virus (HIV) envelope synthetic peptide to a tolerogen in chimpanzees by the fusogenic domain of HIV gp41 envelope protein." Journal of Experimental Medicine 177, no. 3 (March 1, 1993): 717–27. http://dx.doi.org/10.1084/jem.177.3.717.
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The fusogenic (F) domain of human immunodeficiency virus (HIV) gp41 envelope (env) protein has sequence similarities to many virus and mediates the fusion of HIV-infected cells. During a survey of the immunogenicity of HIV env peptides in chimpanzees, we have observed that HIV peptide immunogenicity was dramatically altered by the NH2-terminal synthesis of the gp41 F domain to an otherwise immunogenic peptide. We compared two hybrid peptide types comprised of T helper (Th) and B cell epitopes of HIV gp120 env protein for their immunogenicity in chimpanzees. The Th-B epitope hybrid peptides contained the HIV gp120 Th cell determinant, T1 (amino acids [aa] 428-440)-synthesized NH2 terminal to gp120 V3 loop peptides, which contain B cell epitopes that induce anti-HIV-neutralizing antibodies (SP10IIIB [aa 303-321] and SP10IIIB [A] [aa 303-327]). The F-Th-B peptide contained the HIV gp41 F domain of HIVIIIB gp41 (aa 519-530)-synthesized NH2 terminal to the Th-B peptide. Whereas Th-B peptides were potent immunogens for chimpanzee antibody and T cell-proliferative responses, the F-Th-B peptide induced lower anti-HIV gp120 T and B cell responses. Moreover, immunization of chimpanzees with F-Th-B peptide but not Th-B peptides induced a significant decrease in peripheral blood T lymphocytes (mean decrease during immunization, 52%; p < 0.02). Chimpanzees previously immunized with F-Th-B peptide did not respond well to immunization with Th-B peptide with T or B cell responses to HIV peptides, demonstrating that the F-Th-B peptide induced immune hyporesponsiveness to Th and B HIV gp120 env determinants. These observations raise the hypothesis that the HIV gp41 env F domain may be a biologically active immunoregulatory peptide in vivo, and by an as yet uncharacterized mechanism, promotes primate immune system hyporesponsiveness to otherwise immunogenic peptides.
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Archibald, David W., Carla A. Hebert, Kevin L. Gregory, and George K. Lewis. "Effects of Human Salivas on Recombinant HIV-1 Proteins." Critical Reviews in Oral Biology & Medicine 4, no. 3 (April 1993): 475–78. http://dx.doi.org/10.1177/10454411930040033101.
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Human saliva appears to contain factors that are inhibitory to HIV-1 infectivity in vitro. We investigated the effect of incubating human whole, parotid, labial minor salivary gland and sublingual/submandibular salivas with recombinant HIV-1 envelope protein (gpl60). Saliva/gpl60 mixtures were run on polyacrylamide gels, transferred to nitrocellulose, and assayed for the presence of gp 160 using monoclonal antibodies or HIV-1-positive sera. Incubation of the gp 160 with whole saliva reduced the intensity of gp 160 bands to 35% of control values. Minor salivary gland saliva reduced the band intensities to 65% of control values, while other saliva types diminished gp160 to 75% of control values. Protease inhibitors had no effect. Components of untreated whole human saliva prevent the detection of the HIV-1 envelope protein gp 160 by antibodies to gp120 and gp41 in immunoblots. The results suggest that complexes between whole saliva factors and certain domains of gp160 block monoclonal antibody binding or are unable to migrate through polyacrylamide gels.
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Corasaniti, M. Tiziana, Giacinto Bagetta, Domenicantonio Rotiroti, and Giuseppe Nisticò. "The HIV Envelope Protein gp120 in the Nervous System." Biochemical Pharmacology 56, no. 2 (July 1998): 153–56. http://dx.doi.org/10.1016/s0006-2952(98)00044-6.
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Guo, Qi, Hsu-Tso Ho, Ira Dicker, Li Fan, Nannan Zhou, Jacques Friborg, Tao Wang, et al. "Biochemical and Genetic Characterizations of a Novel Human Immunodeficiency Virus Type 1 Inhibitor That Blocks gp120-CD4 Interactions." Journal of Virology 77, no. 19 (October 1, 2003): 10528–36. http://dx.doi.org/10.1128/jvi.77.19.10528-10536.2003.
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ABSTRACT BMS-378806 is a recently discovered small-molecule human immunodeficiency virus type 1 (HIV-1) attachment inhibitor with good antiviral activity and pharmacokinetic properties. Here, we demonstrate that the compound targets viral entry by inhibiting the binding of the HIV-1 envelope gp120 protein to cellular CD4 receptors via a specific and competitive mechanism. BMS-378806 binds directly to gp120 at a stoichiometry of approximately 1:1, with a binding affinity similar to that of soluble CD4. The potential BMS-378806 target site was localized to a specific region within the CD4 binding pocket of gp120 by using HIV-1 gp120 variants carrying either compound-selected resistant substitutions or gp120-CD4 contact site mutations. Mapping of resistance substitutions to the HIV-1 envelope, and the lack of compound activity against a CD4-independent viral infection confirm the gp120-CD4 interactions as the target in infected cells. BMS-378806 therefore serves as a prototype for this new class of antiretroviral agents and validates gp120 as a viable target for small-molecule inhibitors.
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Lee, Young-Jung, In Jun Yeo, Dong Young Choi, Jaesuk Yun, Dong Ju Son, Sang-Bae Han, and Jin Tae Hong. "Amyloidogenic, neuroinflammatory and memory dysfunction effects of HIV-1 gp120." Archives of Pharmacal Research 44, no. 7 (July 2021): 689–701. http://dx.doi.org/10.1007/s12272-021-01340-8.
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AbstractHuman immunodeficiency virus 1 (HIV-1) infection can cause several HIV-associated neurocognitive disorders a variety of neurological impairments characterized by the loss of cortical and subcortical neurons and decreased cognitive and motor function. HIV-1 gp120, the major envelope glycoprotein on viral particles, acts as a binding protein for viral entry and is known to be an agent of neuronal cell death. To determine the mechanism of HIV-1 gp120-induced memory dysfunction, we performed mouse intracerebroventricular (i.c.v.) infusion with HIV-1 gp120 protein (300 ng per mouse) and investigated memory impairment and amyloidogenesis. Infusion of the HIV-1 gp120 protein induced memory dysfunction, which was evaluated using passive avoidance and water maze tests. Infusion of HIV-1 gp120 induced neuroinflammation, such as the release of iNOS and COX-2 and the activation of astrocytes and microglia and increased the mRNA and protein levels of IL-6, ICAM-1, M-CSF, TIM, and IL-2. In particular, we found that the infusion of HIV-1 gp120 induced the accumulation of amyloid plaques and signs of elevated amyloidogenesis, such as increased expression of amyloid precursor protein and BACE1 and increased β-secretase activity. Therefore, these studies suggest that HIV-1 gp120 may induce memory impairment through Aβ accumulation and neuroinflammation.
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Derby, Nina R., Zane Kraft, Elaine Kan, Emma T. Crooks, Susan W. Barnett, Indresh K. Srivastava, James M. Binley, and Leonidas Stamatatos. "Antibody Responses Elicited in Macaques Immunized with Human Immunodeficiency Virus Type 1 (HIV-1) SF162-Derived gp140 Envelope Immunogens: Comparison with Those Elicited during Homologous Simian/Human Immunodeficiency Virus SHIVSF162P4 and Heterologous HIV-1 Infection." Journal of Virology 80, no. 17 (September 1, 2006): 8745–62. http://dx.doi.org/10.1128/jvi.00956-06.
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ABSTRACT The antibody responses elicited in rhesus macaques immunized with soluble human immunodeficiency virus (HIV) Env gp140 proteins derived from the R5-tropic HIV-1 SF162 virus were analyzed and compared to the broadly reactive neutralizing antibody responses elicited during chronic infection of a macaque with a simian/human immunodeficiency virus (SHIV) expressing the HIV-1 SF162 Env, SHIVSF162P4, and humans infected with heterologous HIV-1 isolates. Four gp140 immunogens were evaluated: SF162gp140, ΔV2gp140 (lacking the crown of the V2 loop), ΔV3gp140 (lacking the crown of the V3 loop), and ΔV2ΔV3gp140 (lacking both the V2 and V3 loop crowns). SF162gp140 and ΔV2gp140 have been previously evaluated by our group in a pilot study, but here, a more comprehensive analysis of their immunogenic properties was performed. All four gp140 immunogens elicited stronger anti-gp120 than anti-gp41 antibodies and potent homologous neutralizing antibodies (NAbs) that primarily targeted the first hypervariable region (V1 loop) of gp120, although SF162gp140 also elicited anti-V3 NAbs. Heterologous NAbs were elicited by SF162gp140 and ΔV2gp140 but were weak in potency and narrow in specificity. No heterologous NAbs were elicited by ΔV3gp140 or ΔV2ΔV3gp140. In contrast, the SHIVSF162P4-infected macaque and HIV-infected humans generated similar titers of anti-gp120 and anti-gp41 antibodies and NAbs of significant breadth against primary HIV-1 isolates, which did not target the V1 loop. The difference in V1 loop immunogenicity between soluble gp140 and virion-associated gp160 Env proteins derived from SF162 may be the basis for the observed difference in the breadth of neutralization in sera from the immunized and infected animals studied here.
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Park, Eun Ju, Miroslav K. Gorny, Susan Zolla-Pazner, and Gerald V. Quinnan. "A Global Neutralization Resistance Phenotype of Human Immunodeficiency Virus Type 1 Is Determined by Distinct Mechanisms Mediating Enhanced Infectivity and Conformational Change of the Envelope Complex." Journal of Virology 74, no. 9 (May 1, 2000): 4183–91. http://dx.doi.org/10.1128/jvi.74.9.4183-4191.2000.
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ABSTRACT We have described previously genetic characterization of neutralization-resistant, high-infectivity, and neutralization-sensitive, low-infectivity mutants of human immunodeficiency virus type 1 (HIV-1) MN envelope. The distinct phenotypes of these clones are attributable to six mutations affecting functional interactions between the gp120 C4-V5 regions and the gp41 leucine zipper. In the present study we examined mechanisms responsible for the phenotypic differences between these envelopes using neutralization and immunofluorescence assays (IFA). Most monoclonal antibodies (MAbs) tested against gp120 epitopes (V3, CD4 binding site, and CD4-induced) were 20 to 100 times more efficient at neutralizing pseudovirus expressing sensitive rather than resistant envelope. By IFA cells expressing neutralization sensitive envelope bound MAbs to gp120 epitopes more, but gp41 epitopes less, than neutralization-resistant envelope. This binding difference appeared to reflect conformational change, since it did not correlate with the level of protein expression or gp120-gp41 dissociation. This conformational change was mostly attributable to one mutation, L544P, which contributes to neutralization resistance but not to infectivity enhancement. The V420I mutation, which contributes a major effect to both high infectivity and neutralization resistance, had no apparent effect on conformation. Notably, a conformation-dependent V3 neutralization epitope remained sensitive to neutralization and accessible to binding by MAbs on neutralization-resistant HIV-1 envelope. Sensitivity to sCD4 did not distinguish the clones, suggesting that the phenotypes may be related to post-CD4-binding effects. The results demonstrate that neutralization resistance can be determined by distinguishable effects of mutations, which cause changes in envelope conformation and/or function(s) related to infectivity. A conformation-dependent V3 epitope may be an important target for neutralization of resistant strains of HIV-1.
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Valenzuela-Fernández, Agustín, Susana Álvarez, Mónica Gordon-Alonso, Marta Barrero, Ángeles Ursa, J. Román Cabrero, Gerónimo Fernández, et al. "Histone Deacetylase 6 Regulates Human Immunodeficiency Virus Type 1 Infection." Molecular Biology of the Cell 16, no. 11 (November 2005): 5445–54. http://dx.doi.org/10.1091/mbc.e05-04-0354.
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Efficient human immunodeficiency virus (HIV)-1 infection depends on multiple interactions between the viral gp41/gp120 envelope (Env) proteins and cell surface receptors. However, cytoskeleton-associated proteins that modify membrane dynamics may also regulate the formation of the HIV-mediated fusion pore and hence viral infection. Because the effects of HDAC6-tubulin deacetylase on cortical α-tubulin regulate cell migration and immune synapse organization, we explored the possible role of HDAC6 in HIV-1-envelope-mediated cell fusion and infection. The binding of the gp120 protein to CD4+-permissive cells increased the level of acetylated α-tubulin in a CD4-dependent manner. Furthermore, overexpression of active HDAC6 inhibited the acetylation of α-tubulin, and remarkably, prevented HIV-1 envelope-dependent cell fusion and infection without affecting the expression and codistribution of HIV-1 receptors. In contrast, knockdown of HDAC6 expression or inhibition of its tubulin deacetylase activity strongly enhanced HIV-1 infection and syncytia formation. These results demonstrate that HDAC6 plays a significant role in regulating HIV-1 infection and Env-mediated syncytia formation.
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Forsman, Anna, Els Beirnaert, Marlén M. I. Aasa-Chapman, Bart Hoorelbeke, Karolin Hijazi, Willie Koh, Vanessa Tack, et al. "Llama Antibody Fragments with Cross-Subtype Human Immunodeficiency Virus Type 1 (HIV-1)-Neutralizing Properties and High Affinity for HIV-1 gp120." Journal of Virology 82, no. 24 (October 8, 2008): 12069–81. http://dx.doi.org/10.1128/jvi.01379-08.
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ABSTRACT Members of the Camelidae family produce immunoglobulins devoid of light chains. We have characterized variable domains of these heavy chain antibodies, the VHH, from llamas immunized with human immunodeficiency virus type 1 (HIV-1) envelope protein gp120 in order to identify VHH that can inhibit HIV-1 infection. To increase the chances of isolating neutralizing VHH, we employed a functional selection approach, involving panning of phage libraries expressing the VHH repertoire on recombinant gp120, followed by a competitive elution with soluble CD4. By immunizing with gp120 derived from an HIV-1 subtype B′/C primary isolate, followed by panning on gp120 from HIV-1 isolates of subtypes A, B, and C, we could select for VHH with cross-subtype neutralizing activity. Three VHH able to neutralize HIV-1 primary isolates of subtypes B and C were characterized. These bound to recombinant gp120 with affinities close to the suggested affinity ceiling for in vivo-maturated antibodies and competed with soluble CD4 for this binding, indicating that their mechanism of neutralization involves interacting with the functional envelope spike prior to binding to CD4. The most potent VHH in terms of low 50% inhibitory concentration (IC50) and IC90 values and cross-subtype reactivity was A12. These results indicate that camelid VHH can be potent HIV-1 entry inhibitors. Since VHH are stable and can be produced at a relatively low cost, they may be considered for applications such as HIV-1 microbicide development. Antienvelope VHH might also prove useful in defining neutralizing and nonneutralizing epitopes on HIV-1 envelope proteins, with implications for HIV-1 vaccine design.
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Hart, T. K., A. M. Klinkner, J. Ventre, and P. J. Bugelski. "Morphometric analysis of envelope glycoprotein gp120 distribution on HIV-1 virions." Journal of Histochemistry & Cytochemistry 41, no. 2 (February 1993): 265–71. http://dx.doi.org/10.1177/41.2.7678271.
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The surface of HIV-1, like that of other retroviruses, is studied with virally encoded glycoproteins which appear ultrastructurally as electron-dense spikes or knobs. The glycoprotein that forms the spike structure, gp120, is non-covalently bound to the transmembrane glycoprotein gp41. Mature HIV-1 virions do not have as many spikes as the genetically related retroviruses HIV-2 and SIV. gp120 is lost from HIV-1 during viral morphogenesis and after incubation of the virus with the soluble form of cellular receptor CD4. In this study we used ultrastructural cytochemistry and morphometry to quantitate the distribution of envelope glycoprotein spikes on budding and mature HIV-1 virions and to look for alternatives to the laborious and somewhat subjective spike-counting technique for envelope spike analysis on HIV-1. HIV-1, strain HTLV-IIIB, was examined after staining of envelope glycoproteins with either tannic acid, immunogold staining for gp120 (gp120-immunogold), or lectin-gold staining with concanavalin A for mannose residues (ConA-HRP-gold) and frequency distributions of spikes or gold particles per micron HIV-1 membrane generated. Envelope spikes were normally distributed on membranes of budding and mature HIV-1. However, the density of spikes per micron viral membrane on mature HIV-1 virions was approximately 50% of that observed on budding virions. ConA-HRP-gold and gp120-immunogold did not efficiently label budding virions. The shape of the frequency distribution for ConA-HRP-gold particles on mature virions was similar to that for envelope spikes and could be used to quantitate envelope glycoproteins on HIV-1. In addition, ConA-HRP-gold staining was able to detect the loss of envelope proteins after treatment of virus with soluble CD4. gp120-immunogold labeling was patchy and many virions were unlabeled. ConA-HRP-gold staining proved to be a rapid, reliable, and easily quantifiable method for estimation of envelope glycoprotein density on mature HIV-1. However, the loss of spike structures throughout the life cycle of HIV-1 can effectively be determined only by direct spike counting.
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Valentín-Guillama, Gabriel, Sheila López, Yuriy Kucheryavykh, Nataliya Chorna, Jose Pérez, Jescelica Ortiz-Rivera, Michael Inyushin, et al. "HIV-1 Envelope Protein gp120 Promotes Proliferation and the Activation of Glycolysis in Glioma Cell." Cancers 10, no. 9 (September 1, 2018): 301. http://dx.doi.org/10.3390/cancers10090301.
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Patients infected with human immunodeficiency virus (HIV) are more prone to developing cancers, including glioblastomas (GBMs). The median survival for HIV positive GBM patients is significantly shorter than for those who are uninfected, despite the fact that they receive the same treatments. The nature of the GBM–HIV association remains poorly understood. In this study, we analyzed the effect of the HIV envelope glycoprotein gp120 on GBM cell proliferation. Specifically, we performed cell cycle, western blot, protein synthesis and metabolomics analysis as well as ATP production and oxygen consumption assays to evaluate proliferation and metabolic pathways in primary human glioma cell line, U87, A172 cells and in the HIVgp120tg/GL261 mouse model. Glioma cells treated with gp120 (100 ng/mL for 7–10 days) showed higher proliferation rates and upregulation in the expression of enolase 2, hexokinase and glyceraldehyde-3-phosphate dehydrogenase when compared to untreated cells. Furthermore, we detected an increase in the activity of pyruvate kinase and a higher glycolytic index in gp120 treated cells. Gp120 treated GBM cells also showed heightened lipid and protein synthesis. Overall, we demonstrate that in glioma cells, the HIV envelope glycoprotein promotes proliferation and activation of glycolysis resulting in increased protein and lipid synthesis.
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Li, Y., K. Svehla, N. L. Mathy, G. Voss, J. R. Mascola, and R. Wyatt. "Characterization of Antibody Responses Elicited by Human Immunodeficiency Virus Type 1 Primary Isolate Trimeric and Monomeric Envelope Glycoproteins in Selected Adjuvants." Journal of Virology 80, no. 3 (February 1, 2006): 1414–26. http://dx.doi.org/10.1128/jvi.80.3.1414-1426.2006.
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ABSTRACT We previously reported that soluble, stable YU2 gp140 trimeric human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein immunogens could elicit improved breadth of neutralization against HIV-1 isolates compared to monomeric YU2 gp120 proteins. In this guinea pig immunization study, we sought to extend these data and determine if adjuvant could quantitatively or qualitatively alter the neutralizing response elicited by trimeric or monomeric immunogens. Consistent with our earlier studies, the YU2 gp140 immunogens elicited higher-titer neutralizing antibodies against homologous and heterologous isolates than those elicited by monomeric YU2 gp120. Additionally, the GlaxoSmithKline family of adjuvants AS01B, AS02A, and AS03 induced higher levels of neutralizing antibodies compared to emulsification of the same immunogens in Ribi adjuvant. Further analysis of vaccine sera indicated that homologous virus neutralization was not mediated by antibodies to the V3 loop, although V3 loop-directed neutralization could be detected for some heterologous isolates. In most gp120-inoculated animals, the homologous YU2 neutralization activity was inhibited by a peptide derived from the YU2 V1 loop, whereas the neutralizing activity elicited by YU2 gp140 trimers was much less sensitive to V1 peptide inhibition. Consistent with a less V1-focused antibody response, sera from the gp140-immunized animals more efficiently neutralized heterologous HIV-1 isolates, as determined by two distinct neutralization formats. Thus, there appear to be qualitative differences in the neutralizing antibody response elicited by YU2 gp140 compared to YU2 monomeric gp120. Further mapping analysis of more conserved regions of gp120/gp41 may be required to determine the neutralizing specificity elicited by the trimeric immunogens.
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Go, Eden P., Alon Herschhorn, Christopher Gu, Luis Castillo-Menendez, Shijian Zhang, Youdong Mao, Haiyan Chen, et al. "Comparative Analysis of the Glycosylation Profiles of Membrane-Anchored HIV-1 Envelope Glycoprotein Trimers and Soluble gp140." Journal of Virology 89, no. 16 (May 27, 2015): 8245–57. http://dx.doi.org/10.1128/jvi.00628-15.
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ABSTRACTThe human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer, which consists of the gp120 and gp41 subunits, is the focus of multiple strategies for vaccine development. Extensive Env glycosylation provides HIV-1 with protection from the immune system, yet the glycans are also essential components of binding epitopes for numerous broadly neutralizing antibodies. Recent studies have shown that when Env is isolated from virions, its glycosylation profile differs significantly from that of soluble forms of Env (gp120 or gp140) predominantly used in vaccine discovery research. Here we show that exogenous membrane-anchored Envs, which can be produced in large quantities in mammalian cells, also display a virion-like glycan profile, where the glycoprotein is extensively decorated with high-mannose glycans. Additionally, because we characterized the glycosylation with a high-fidelity profiling method, glycopeptide analysis, an unprecedented level of molecular detail regarding membrane Env glycosylation and its heterogeneity is presented. Each glycosylation site was characterized individually, with about 500 glycoforms characterized per Env protein. While many of the sites contain exclusively high-mannose glycans, others retain complex glycans, resulting in a glycan profile that cannot currently be mimicked on soluble gp120 or gp140 preparations. These site-level studies are important for understanding antibody-glycan interactions on native Env trimers. Additionally, we report a newly observedO-linked glycosylation site, T606, and we show that the fullO-linked glycosylation profile of membrane-associated Env is similar to that of soluble gp140. These findings provide new insight into Env glycosylation and clarify key molecular-level differences between membrane-anchored Env and soluble gp140.IMPORTANCEA vaccine that protects against human immunodeficiency virus type 1 (HIV-1) infection should elicit antibodies that bind to the surface envelope glycoproteins on the membrane of the virus. The envelope glycoproteins have an extensive coat of carbohydrates (glycans), some of which are recognized by virus-neutralizing antibodies and some of which protect the virus from neutralizing antibodies. We found that the HIV-1 membrane envelope glycoproteins have a unique pattern of carbohydrates, with many high-mannose glycans and also, in some places, complex glycans. This pattern was very different from the carbohydrate profile seen for a more easily produced soluble version of the envelope glycoprotein. Our results provide a detailed characterization of the glycans on the natural membrane envelope glycoproteins of HIV-1, a carbohydrate profile that would be desirable to mimic with a vaccine.
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Kashyn, I. A., G. I. Nikolaev, M. A. Tuzikov, and A. M. Andrianov. "Molecular dynamics for structural complexes of potential HIV-1 inhibitors with the viral envelope gp120 protein." Doklady of the National Academy of Sciences of Belarus 62, no. 5 (October 30, 2018): 576–84. http://dx.doi.org/10.29235/1561-8323-2018-62-5-576-584.
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Molecular dynamics simulations for the structural complexes of potential HIV-1 inhibitors with the viral envelope gp120 protein were carried out. Free energies of the formation of these supramolecular structures and contributions of individual amino-acid residues of gp120 to the enthalpy binding were calculated. The residues of gp120 critical for interactions with the ligands were identified. Based on the data obtained, five compounds promising for synthesis and testing for antiviral activity were selected. It is suggested that these compounds may be successfully used in the design of novel, potent and broad anti-HIV drugs.
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Biragyn, Arya, Igor M. Belyakov, Yen-Hung Chow, Dimiter S. Dimitrov, Jay A. Berzofsky, and Larry W. Kwak. "DNA vaccines encoding human immunodeficiency virus–1 glycoprotein 120 fusions with proinflammatory chemoattractants induce systemic and mucosal immune responses." Blood 100, no. 4 (August 15, 2002): 1153–59. http://dx.doi.org/10.1182/blood-2002-01-0086.
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DNA immunizations with glycoprotein 120 (gp120) of human immunodeficiency virus–1 (HIV-1) usually require boosting with protein or viral vaccines to achieve optimal efficacy. Here, we demonstrate for the first time that mice immunized with DNA encoding gp120 fused with proinflammatory chemoattractants of immature dendritic cells, such as β-defensin 2, monocyte chemoattractant protein–3 (MCP-3/CCL7) or macrophage-derived chemokine (MDC/CCL22), elicited anti-gp120 antibodies with high titers of virus-neutralizing activity. The immunogenicity was further augmented with the use of chemokine fusion constructs with gp140, gp120 linked to the extracellular domain of gp41 via a 14–amino acid spacer peptide sequence. This construct elicited antibodies with more effective neutralizing activity than corresponding constructs expressing gp120. Responses were dependent on physical linkage with chemokine moiety, as no immunity was detected following immunization of mice with DNA encoding a free mixture of chemokine and gp120. Although the route of immunization was inoculation into skin, both systemic and mucosal CD8+ cytolytic immune responses were elicited in mice immunized with DNA expressing MCP-3 or β-defensin 2 fusion constructs. In contrast, no cytotoxic T lymphocyte activity (CTL) was detected in mice immunized with DNA encoding gp120 either alone or as fusion with MDC. Therefore, the potential for broad application of this approach lies in the induction of mucosal CTL and neutralizing antibodies to HIV-1 envelope, both key requirements for prevention of viral transmission and clearance of pathogenic HIV from mucosal reservoirs.
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Yang, Xinzhen, Richard Wyatt, and Joseph Sodroski. "Improved Elicitation of Neutralizing Antibodies against Primary Human Immunodeficiency Viruses by Soluble Stabilized Envelope Glycoprotein Trimers." Journal of Virology 75, no. 3 (February 1, 2001): 1165–71. http://dx.doi.org/10.1128/jvi.75.3.1165-1171.2001.
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ABSTRACT Human immunodeficiency virus (HIV-1) envelope glycoprotein subunits, such as the gp120 exterior glycoprotein, typically elicit antibodies that neutralize T-cell-line-adapted (TCLA), but not primary, clinical isolates of HIV-1. Here we compare the immunogenicity of gp120 and soluble stabilized trimers, which were designed to resemble the functional envelope glycoprotein oligomers of primary and TCLA HIV-1 strains. For both primary and TCLA virus proteins, soluble stabilized trimers generated neutralizing antibody responses more efficiently than gp120 did. Trimers derived from a primary isolate elicited antibodies that neutralized primary and TCLA HIV-1 strains. By contrast, trimers derived from a TCLA isolate generated antibodies that neutralized only the homologous TCLA virus. Thus, soluble stabilized envelope glycoprotein trimers derived from primary HIV-1 isolates represent defined immunogens capable of eliciting neutralizing antibodies that are active against clinically relevant HIV-1 strains.
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Doria-Rose, N. A., G. H. Learn, A. G. Rodrigo, D. C. Nickle, F. Li, M. Mahalanabis, M. T. Hensel, et al. "Human Immunodeficiency Virus Type 1 Subtype B Ancestral Envelope Protein Is Functional and Elicits Neutralizing Antibodies in Rabbits Similar to Those Elicited by a Circulating Subtype B Envelope." Journal of Virology 79, no. 17 (September 1, 2005): 11214–24. http://dx.doi.org/10.1128/jvi.79.17.11214-11224.2005.
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ABSTRACT Human immunodeficiency virus type 1 (HIV-1) is a difficult target for vaccine development, in part because of its ever-expanding genetic diversity and attendant capacity to escape immunologic recognition. Vaccine efficacy might be improved by maximizing immunogen antigenic similarity to viruses likely to be encountered by vaccinees. To this end, we designed a prototype HIV-1 envelope vaccine using a deduced ancestral state for the env gene. The ancestral state reconstruction method was shown to be >95% accurate by computer simulation and 99.8% accurate when estimating the known inoculum used in an experimental infection study in rhesus macaques. Furthermore, the deduced ancestor gene differed from the set of sequences used to derive the ancestor by an average of 12.3%, while these latter sequences were an average of 17.3% different from each other. A full-length ancestral subtype B HIV-1 env gene was constructed and shown to produce a glycoprotein of 160 kDa that bound and fused with cells expressing the HIV-1 coreceptor CCR5. This Env was also functional in a virus pseudotype assay. When either gp160- or gp140-expressing plasmids and recombinant gp120 were used to immunize rabbits in a DNA prime-protein boost regimen, the artificial gene induced immunoglobulin G antibodies capable of weakly neutralizing heterologous primary HIV-1 strains. The results were similar for rabbits immunized in parallel with a natural isolate, HIV-1 SF162. Further design efforts to better present conserved neutralization determinants are warranted.
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Ivey-Hoyle, M., and M. Rosenberg. "Rev-dependent expression of human immunodeficiency virus type 1 gp160 in Drosophila melanogaster cells." Molecular and Cellular Biology 10, no. 12 (December 1990): 6152–59. http://dx.doi.org/10.1128/mcb.10.12.6152.
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Expression of the human immunodeficiency virus (HIV) structural proteins in mammalian cells is regulated posttranscriptionally by the viral Rev protein. Rev has been shown to trans-activate expression by relieving the nuclear sequestration of RNAs containing viral gag or env coding regions. We have studied the effects of Rev on expression of the HIV type 1 env gene in Drosophila melanogaster cells. We demonstrated that synthesis of the gp160 envelope protein was fully Rev dependent; that is, gp160 was produced only when Rev function was coexpressed in the cell. Analysis of total cellular RNA indicated that Rev did not significantly affect the overall levels of gp160 RNA production. Instead, mRNA encoding gp160 was found in the cytoplasm only in cells expressing Rev, whereas in cells lacking Rev, this RNA was present only in the nucleus. Furthermore, comparison of these results with the previously demonstrated Rev-independent expression of gp120 envelope protein with this system indicated that information contained in the gp41 coding region appears to be critical to the selective nuclear retention of gp160 transcripts in the absence of Rev. Our results clearly demonstrate that the mechanism of Rev action is conserved in the insect cell system, and, thus, Rev must function via cellular machinery common to most, if not all, higher cell systems.
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Ivey-Hoyle, M., and M. Rosenberg. "Rev-dependent expression of human immunodeficiency virus type 1 gp160 in Drosophila melanogaster cells." Molecular and Cellular Biology 10, no. 12 (December 1990): 6152–59. http://dx.doi.org/10.1128/mcb.10.12.6152-6159.1990.
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Expression of the human immunodeficiency virus (HIV) structural proteins in mammalian cells is regulated posttranscriptionally by the viral Rev protein. Rev has been shown to trans-activate expression by relieving the nuclear sequestration of RNAs containing viral gag or env coding regions. We have studied the effects of Rev on expression of the HIV type 1 env gene in Drosophila melanogaster cells. We demonstrated that synthesis of the gp160 envelope protein was fully Rev dependent; that is, gp160 was produced only when Rev function was coexpressed in the cell. Analysis of total cellular RNA indicated that Rev did not significantly affect the overall levels of gp160 RNA production. Instead, mRNA encoding gp160 was found in the cytoplasm only in cells expressing Rev, whereas in cells lacking Rev, this RNA was present only in the nucleus. Furthermore, comparison of these results with the previously demonstrated Rev-independent expression of gp120 envelope protein with this system indicated that information contained in the gp41 coding region appears to be critical to the selective nuclear retention of gp160 transcripts in the absence of Rev. Our results clearly demonstrate that the mechanism of Rev action is conserved in the insect cell system, and, thus, Rev must function via cellular machinery common to most, if not all, higher cell systems.
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Bower, Joseph F., Xinzhen Yang, Joseph Sodroski, and Ted M. Ross. "Elicitation of Neutralizing Antibodies with DNA Vaccines Expressing Soluble Stabilized Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Trimers Conjugated to C3d." Journal of Virology 78, no. 9 (May 1, 2004): 4710–19. http://dx.doi.org/10.1128/jvi.78.9.4710-4719.2004.
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ABSTRACT DNA vaccines expressing the envelope (Env) of human immunodeficiency virus type 1 (HIV-1) have been relatively ineffective at generating high-titer, long-lasting immune responses. Oligomeric or trimeric (gp140) forms of Env that more closely mimic the native proteins on the virion are often more effective immunogens than monomeric (gp120) envelopes. In this study, several forms of Env constructed from the HIV-1 isolate YU-2 (HIV-1YU-2) were tested for their immunogenic potential: a trimeric form of uncleaved (−) Env stabilized with a synthetic trimer motif isolated from the fibritin (FT) protein of the T4 bacteriophage, sgp140YU-2(−/FT), was compared to sgp140YU-2(−) without a synthetic trimerization domain, as well as to monomeric gp120YU-2. DNA plasmids were constructed to express Env alone or fused to various copies of murine C3d (mC3d). BALB/c mice were vaccinated (day 1 and week 4) with DNA expressing a codon-optimized envelope gene insert, alone or fused to mC3d. Mice were subsequently boosted (week 8) with the DNA or recombinant Env protein. All mice had high anti-Env antibody titers regardless of the use of mC3d. Sera from mice vaccinated with DNA expressing non-C3d-fused trimers elicited neutralizing antibodies against homologous HIV-1YU-2 virus infection in vitro. In contrast, sera from mice inoculated with DNA expressing Env-C3d protein trimers elicited antibody that neutralized both homologous HIV-1YU-2 and heterologous HIV-1ADA, albeit at low titers. Therefore, DNA vaccines expressing trimeric envelopes coupled to mC3d, expressed in vivo from codon-optimized sequences, elicit low titers of neutralizing antibodies against primary isolates of HIV-1.
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Esser, Mark T., Toshiyuki Mori, Isabelle Mondor, Quentin J. Sattentau, Barna Dey, Edward A. Berger, Michael R. Boyd, and Jeffrey D. Lifson. "Cyanovirin-N Binds to gp120 To Interfere with CD4-Dependent Human Immunodeficiency Virus Type 1 Virion Binding, Fusion, and Infectivity but Does Not Affect the CD4 Binding Site on gp120 or Soluble CD4-Induced Conformational Changes in gp120." Journal of Virology 73, no. 5 (May 1, 1999): 4360–71. http://dx.doi.org/10.1128/jvi.73.5.4360-4371.1999.
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ABSTRACT Cyanovirin-N (CV-N), an 11-kDa protein isolated from the cyanobacterium Nostoc ellipsosporum, potently inactivates diverse strains of human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus. While it has been well established that the viral surface envelope glycoprotein gp120 is a molecular target of CV-N, the detailed mechanism of action is of further interest. We compared matched native and CV-N-treated virus preparations in a panel of assays that measure viral replication, assessing successive stages of the viral life cycle. CV-N-treated virions failed to infect cells as detected by p24 production and quantitative PCR for HIV-1 reverse transcription products, whereas treatment of the target cells did not block infection, confirming that CV-N acts at the level of the virus, not the target cell, to abort the initial infection process. Compared to native HIV-1 preparations, CV-N-treated HIV-1 virions showed impaired CD4-dependent binding to CD4+ T cells and did not mediate “fusion from without” of CD4+ target cells. CV-N also blocked HIV envelope glycoprotein Env-induced, CD4-dependent cell-cell fusion. Mapping studies with monoclonal antibodies (MAbs) to defined epitopes on the HIV-1 envelope glycoprotein indicated that CV-N binds to gp120 in a manner that does not occlude or alter the CD4 binding site or V3 loop or other domains on gp120 recognized by defined MAbs and does not interfere with soluble CD4-induced conformational changes in gp120. Binding of CV-N to soluble gp120 or virions inhibited subsequent binding of the unique neutralizing MAb 2G12, which recognizes a glycosylation-dependent epitope. However, prior binding of 2G12 MAb to gp120 did not block subsequent binding by CV-N. These results help clarify the mechanism of action of CV-N and suggest that the compound may act in part by preventing essential interactions between the envelope glycoprotein and target cell receptors. This proposed mechanism is consistent with the extensive activity profile of CV-N against numerous isolates of HIV-1 and other lentiviruses and supports the potential broad utility of this protein as a microbicide to prevent the sexual transmission of HIV.
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Pérez, Patricia, María Q. Marín, Adrián Lázaro-Frías, Carlos Óscar S. Sorzano, Mauro Di Pilato, Carmen E. Gómez, Mariano Esteban, and Juan García-Arriaza. "An MVA Vector Expressing HIV-1 Envelope under the Control of a Potent Vaccinia Virus Promoter as a Promising Strategy in HIV/AIDS Vaccine Design." Vaccines 7, no. 4 (December 6, 2019): 208. http://dx.doi.org/10.3390/vaccines7040208.
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Highly attenuated poxviral vectors, such as modified vaccinia virus ankara (MVA), are promising vaccine candidates against several infectious diseases. One of the approaches developed to enhance the immunogenicity of poxvirus vectors is increasing the promoter strength and accelerating during infection production levels of heterologous antigens. Here, we have generated and characterized the biology and immunogenicity of an optimized MVA-based vaccine candidate against HIV/AIDS expressing HIV-1 clade B gp120 protein under the control of a novel synthetic late/early optimized (LEO) promoter (LEO160 promoter; with a spacer length of 160 nucleotides), termed MVA-LEO160-gp120. In infected cells, MVA-LEO160-gp120 significantly increased the expression levels of HIV-1 gp120 mRNA and protein, compared to the clinical vaccine MVA-B vector expressing HIV-1 gp120 under the control of the commonly used synthetic early/late promoter. When mice were immunized with a heterologous DNA-prime/MVA-boost protocol, the immunization group DNA-gp120/MVA-LEO160-gp120 induced an enhancement in the magnitude of gp120-specific CD4+ and CD8+ T-cell responses, compared to DNA-gp120/MVA-B; with most of the responses being mediated by the CD8+ T-cell compartment, with a T effector memory phenotype. DNA-gp120/MVA-LEO160-gp120 also elicited a trend to a higher magnitude of gp120-specific CD4+ T follicular helper cells, and modest enhanced levels of antibodies against HIV-1 gp120. These findings revealed that this new optimized vaccinia virus promoter could be considered a promising strategy in HIV/AIDS vaccine design, confirming the importance of early expression of heterologous antigen and its impact on the antigen-specific immunogenicity elicited by poxvirus-based vectors.