scholarly journals Sensitivity to Monoclonal Antibody 447-52D and an Open Env Trimer Conformation Correlate Poorly with Inhibition of HIV-1 Infectivity by SERINC5

2020 ◽  
Author(s):  
Aaron O. Angerstein ◽  
Charlotte A. Stoneham ◽  
Peter W. Ramirez ◽  
John C. Guatelli ◽  
Thomas Vollbrecht
Keyword(s):  
Monoclonal Antibody ◽  
Specific Antibody ◽  
The Other ◽  
Host Protein ◽  
V3 Loop ◽  
Dependent Manner ◽  
Open Conformation ◽  
Hiv 1

AbstractThe host protein SERINC5 inhibits the infectivity of HIV-1 virions in an Env-dependent manner and is counteracted by Nef. The conformation of the Env trimer reportedly correlates with sensitivity to SERINC5. Here, we tested the hypothesis that the “open” conformation of the Env trimer revealed by sensitivity to the V3-loop specific antibody 447-52D directly correlates with sensitivity to SERINC5. Of five Envs tested, SF162 was the most sensitive to neutralization by 447-52D, but it was not the most sensitive to SERINC5; instead the Env of LAI was substantially more sensitive to SERINC5 than all the other Envs. Mutational opening of the trimer by substitution of two tyrosines that mediate interaction between the V2 and V3 loops sensitized the Envs of JRFL and LAI to 447-52D as previously reported, but only BaL was sensitized to SERINC5. These data suggest that trimer “openness” is not sufficient for sensitivity to SERINC5.

Expression and Functional Activity of Isotype and Subclass Switched Human Monoclonal Antibody Reactive with the Base of the V3 Loop of HIV-1 gp120

2003 ◽  
Vol 19 (7) ◽  
pp. 597-607 ◽  
Author(s):  
Fangbing Liu ◽  
Pablo Lopez Bergami ◽  
Mark Duval ◽  
David Kuhrt ◽  
Marshall Posner ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Functional Activity ◽  
Human Monoclonal Antibody ◽  
V3 Loop ◽  
Hiv 1

A Fibrin Specific Monoclonal Antibody which Interferes with the Fibrinolytic Effect of Tissue Plasminogen Activator

1988 ◽  
Vol 59 (03) ◽  
pp. 426-431 ◽  
Author(s):  
P E Gargan ◽  
V A Ploplis ◽  
J D Scheu
Keyword(s):  
Monoclonal Antibody ◽  
Cell Line ◽  
Specific Antibody ◽  
Myeloma Cell ◽  
Dependent Manner ◽  
Mouse Myeloma Cell Line ◽  
Release Assay ◽  
Dose Dependent ◽  
Mouse Myeloma

SummaryMonoclonal antibodies to human fibrin have been prepared from stable hybridomas, obtained by fusion of a mouse myeloma cell line (NS-1) and spleen cells of Balb/c mice immunized with a suspension of human fibrin. One cell line, DG1, producing a monoclonal antibody of the IgG1 κ subclass, reacted specifically with human fibrin (KD = 1.2 nM). Western blotting analysis indicates that DG1 crossreacts with the fibrin fragment D-dimer. Using both a chromogenic and an 125I-fibrin release assay it was illustrated that in the presence of the fibrin specific antibody the t-PA mediated generation of plasmin was significantly inhibited.An animal model system, developed to monitor thrombosis and induced reactive fibrinolysis, was used to investigate the interference of plasminogen activation, by the antibody, in vivo.This fibrin specific antibody prolonged the onset of reactive fibrinolysis in a dose dependent manner.

scholarly journals A broadly neutralizing macaque monoclonal antibody against the HIV-1 V3-Glycan patch

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Zijun Wang ◽  
Christopher O Barnes ◽  
Rajeev Gautam ◽  
Julio C Cetrulo Lorenzi ◽  
Christian T Mayer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibody ◽  
Neutralizing Antibodies ◽  
Geometric Mean ◽  
High Dose ◽  
Dependent Manner ◽  
Peptide Motif ◽  
Broadly Neutralizing Antibodies ◽  
Cryo Electron Microscopy ◽  
Hiv 1

A small fraction of HIV-1- infected humans develop broadly neutralizing antibodies (bNAbs) against HIV-1 that protect macaques from simian immunodeficiency HIV chimeric virus (SHIV). Similarly, a small number of macaques infected with SHIVs develop broadly neutralizing serologic activity, but less is known about the nature of simian antibodies. Here, we report on a monoclonal antibody, Ab1485, isolated from a macaque infected with SHIVAD8 that developed broadly neutralizing serologic activity targeting the V3-glycan region of HIV-1 Env. Ab1485 neutralizes 38.1% of HIV-1 isolates in a 42-pseudovirus panel with a geometric mean IC50 of 0.055 µg/mLl and SHIVAD8 with an IC50 of 0.028 µg/mLl. Ab1485 binds the V3-glycan epitope in a glycan-dependent manner. A 3.5 Å cryo-electron microscopy structure of Ab1485 in complex with a native-like SOSIP Env trimer showed conserved contacts with the N332gp120 glycan and gp120 GDIR peptide motif, but in a distinct Env-binding orientation relative to human V3/N332gp120 glycan-targeting bNAbs. Intravenous infusion of Ab1485 protected macaques from a high dose challenge with SHIVAD8. We conclude that macaques can develop bNAbs against the V3-glycan patch that resemble human V3-glycan bNAbs.

scholarly journals Functional and Structural Characterization of Human V3-Specific Monoclonal Antibody 2424 with Neutralizing Activity against HIV-1 JRFL

2015 ◽  
Vol 89 (17) ◽  
pp. 9090-9102 ◽  
Author(s):  
Rajnish Kumar ◽  
Ruimin Pan ◽  
Chitra Upadhyay ◽  
Luzia Mayr ◽  
Sandra Cohen ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Binding Mode ◽  
Hiv Vaccine ◽  
The Other ◽  
Specific Monoclonal Antibody ◽  
Virus Envelope ◽  
Neutralizing Activity ◽  
Hiv 1

ABSTRACTThe V3 region of HIV-1 gp120 is important for virus-coreceptor interaction and highly immunogenic. Although most anti-V3 antibodies neutralize only the sensitive tier 1 viruses, anti-V3 antibodies effective against the more resistant viruses exist, and a better understanding of these antibodies and their epitopes would be beneficial for the development of novel vaccine immunogens against HIV. The HIV-1 isolate JRFL with its cryptic V3 is resistant to most V3-specific monoclonal antibodies (MAbs). However, the V3 MAb 2424 achieves 100% neutralization against JRFL. 2424 is encoded by IGHV3-53 and IGLV2-28 genes, a pairing rarely used by the other V3 MAbs. 2424 also has distinct binding and neutralization profiles. Studies of 2424-mediated neutralization of JRFL produced with a mannosidase inhibitor further revealed that its neutralizing activity is unaffected by the glycan composition of the virus envelope. To understand the distinct activity of 2424, we determined the crystal structure of 2424 Fab in complex with a JRFL V3 peptide and showed that the 2424 epitope is located at the tip of the V3 crown (307IHIGPGRAFYT319), dominated by interactions with HisP308, ProP313, and ArgP315. The binding mode of 2424 is similar to that of the well-characterized MAb 447-52D, although 2424 is more side chain dependent. The 2424 epitope is focused on the very apex of V3, away from nearby glycans, facilitating antibody access. This feature distinguishes the 2424 epitope from the other V3 crown epitopes and indicates that the tip of V3 is a potential site to target and incorporate into HIV vaccine immunogens.IMPORTANCEHIV/AIDS vaccines are crucial for controlling the HIV epidemics that continue to afflict millions of people worldwide. However, HIV vaccine development has been hampered by significant scientific challenges, one of which is the inability of HIV vaccine candidates evaluated thus far to elicit production of potent and broadly neutralizing antibodies. The V3 loop is one of the few immunogenic targets on the virus envelope glycoprotein that can induce neutralizing antibodies, but in many viruses, parts of V3 are inaccessible for antibody recognition. This study examined a V3-specific monoclonal antibody that can completely neutralize HIV-1 JRFL, a virus isolate resistant to most V3 antibodies. Our data reveal that this antibody recognizes the most distal tip of V3, which is not as occluded as other parts of V3. Hence, the epitope of 2424 is in one of the vulnerable sites on the virus that may be exploited in designing HIV vaccine immunogens.

scholarly journals Naf1 Regulates HIV-1 Latency by Suppressing Viral Promoter-Driven Gene Expression in Primary CD4+ T Cells

2016 ◽  
Vol 91 (1) ◽  
Author(s):  
Chuan Li ◽  
Hai-Bo Wang ◽  
Wen-Dong Kuang ◽  
Xiao-Xin Ren ◽  
Shu-Ting Song ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell Activation ◽  
Nuclear Export ◽  
Therapeutic Strategy ◽  
Host Protein ◽  
Viral Reactivation ◽  
Viral Transcription ◽  
Dependent Manner ◽  
Ltr Promoter ◽  
Hiv 1

ABSTRACT HIV-1 latency is characterized by reversible silencing of viral transcription driven by the long terminal repeat (LTR) promoter of HIV-1. Cellular and viral factors regulating LTR activity contribute to HIV-1 latency, and certain repressive cellular factors modulate viral transcription silencing. Nef-associated factor 1 (Naf1) is a host nucleocytoplasmic shuttling protein that regulates multiple cellular signaling pathways and HIV-1 production. We recently reported that nuclear Naf1 promoted nuclear export of unspliced HIV-1 gag mRNA, leading to increased Gag production. Here we demonstrate new functions of Naf1 in regulating HIV-1 persistence. We found that Naf1 contributes to the maintenance of HIV-1 latency by inhibiting LTR-driven HIV-1 gene transcription in a nuclear factor kappa B-dependent manner. Interestingly, Naf1 knockdown significantly enhanced viral reactivation in both latently HIV-1-infected Jurkat T cells and primary central memory CD4+ T cells. Furthermore, Naf1 knockdown in resting CD4+ T cells from HIV-1-infected individuals treated with antiretroviral therapy significantly increased viral reactivation upon T-cell activation, suggesting an important role of Naf1 in modulating HIV-1 latency in vivo. Our findings provide new insights for a better understanding of HIV-1 latency and suggest that inhibition of Naf1 activity to activate latently HIV-1-infected cells may be a potential therapeutic strategy. IMPORTANCE HIV-1 latency is characterized mainly by a reversible silencing of LTR promoter-driven transcription of an integrated provirus. Cellular and viral proteins regulating LTR activity contribute to the modulation of HIV-1 latency. In this study, we found that the host protein Naf1 inhibited HIV-1 LTR-driven transcription of HIV genes and contributed to the maintenance of HIV-1 latency. Our findings provide new insights into the effects of host modulation on HIV-1 latency, which may lead to a potential therapeutic strategy for HIV persistence by targeting the Naf1 protein.

scholarly journals Structure of Simian Immunodeficiency Virus Envelope Spikes Bound with CD4 and Monoclonal Antibody 36D5

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Guiqing Hu ◽  
Jun Liu ◽  
Kenneth H. Roux ◽  
Kenneth A. Taylor
Keyword(s):  
Monoclonal Antibody ◽  
Immune System ◽  
Binding Site ◽  
Simian Immunodeficiency Virus ◽  
Conformational Dynamics ◽  
V3 Loop ◽  
Coreceptor Binding ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Coreceptor Binding Site

ABSTRACT The human immunodeficiency virus type 1 (HIV-1)/simian immunodeficiency virus (SIV) envelope spike (Env) mediates viral entry into host cells. The V3 loop of the gp120 component of the Env trimer contributes to the coreceptor binding site and is a target for neutralizing antibodies. We used cryo-electron tomography to visualize the binding of CD4 and the V3 loop monoclonal antibody (MAb) 36D5 to gp120 of the SIV Env trimer. Our results show that 36D5 binds gp120 at the base of the V3 loop and suggest that the antibody exerts its neutralization effect by blocking the coreceptor binding site. The antibody does this without altering the dynamics of the spike motion between closed and open states when CD4 is bound. The interaction between 36D5 and SIV gp120 is similar to the interaction between some broadly neutralizing anti-V3 loop antibodies and HIV-1 gp120. Two conformations of gp120 bound with CD4 are revealed, suggesting an intrinsic dynamic nature of the liganded Env trimer. CD4 binding substantially increases the binding of 36D5 to gp120 in the intact Env trimer, consistent with CD4-induced changes in the conformation of gp120 and the antibody binding site. Binding by MAb 36D5 does not substantially alter the proportions of the two CD4-bound conformations. The position of MAb 36D5 at the V3 base changes little between conformations, indicating that the V3 base serves as a pivot point during the transition between these two states. IMPORTANCE Glycoprotein spikes on the surfaces of SIV and HIV are the sole targets available to the immune system for antibody neutralization. Spikes evade the immune system by a combination of a thick layer of polysaccharide on the surface (the glycan shield) and movement between spike domains that masks the epitope conformation. Using SIV virions whose spikes were “decorated” with the primary cellular receptor (CD4) and an antibody (36D5) at part of the coreceptor binding site, we visualized multiple conformations trapped by the rapid freezing step, which were separated using statistical analysis. Our results show that the CD4-induced conformational dynamics of the spike enhances binding of the antibody.

scholarly journals T-Tropic Human Immunodeficiency Virus Type 1 (HIV-1)-Derived V3 Loop Peptides Directly Bind to CXCR-4 and Inhibit T-Tropic HIV-1 Infection

1998 ◽  
Vol 72 (12) ◽  
pp. 9763-9770 ◽  
Author(s):  
Hitoshi Sakaida ◽  
Toshiyuki Hori ◽  
Akihito Yonezawa ◽  
Akihiko Sato ◽  
Yoshitaka Isaka ◽  
...  
Keyword(s):  
Cell Line ◽  
Viral Entry ◽  
Chemokine Receptors ◽  
V3 Loop ◽  
Dependent Manner ◽  
Immunodeficiency Virus ◽  
Intracellular Ca ◽  
Reverse Transcriptase Assay ◽  
Dose Dependent ◽  
Hiv 1

ABSTRACT Certain types of chemokine receptors have been identified as coreceptors for HIV-1 infection. The process of viral entry is initiated by the interaction between an envelope protein gp120 of HIV-1, CD4, and one of the relevant coreceptors. To understand the precise mechanism of the Env-mediated fusion and entry of HIV-1, we examined whether the V3 region of gp120 of T-cell line tropic (T-tropic) virus directly interacts with the coreceptor, CXCR-4, by using five synthetic V3 peptides: two cyclized V3 peptides (V3-BH10 and V3-ELI) which correspond to the V3 regions of the T-tropic HIV-1 IIIB and HIV-1 ELI strains, respectively, a linear V3 peptide (CTR36) corresponding to that of HIV-1 IIIB strain; and cyclized V3 peptides corresponding to that of the macrophage-tropic (M-tropic) HIV-1 ADA strain (V3-ADA) or the dualtropic HIV-1 89.6 strain (V3-89.6). FACScan analysis with a CXCR-4+ human B-cell line, JY, showed that V3-BH10, V3-ELI, and V3-89.6 but not CTR36 or V3-ADA blocked the binding of IVR7, an anti-CXCR-4 monoclonal antibody (MAb), to CXCR-4 with different magnitudes in a dose-dependent manner, while none of the V3 peptides influenced binding of an anti-CD19 MAb at all. Next, the effects of the V3 peptides on SDF-1β-induced transient increases in intracellular Ca2+ were investigated. Three V3 peptides (V3-BH10, V3-ELI, and V3-89.6) prevented Ca2+mobilization. Furthermore, the three peptides inhibited infection by T-tropic HIV-1 in a dose-dependent manner as revealed by an MTT assay and a reverse transcriptase assay, while the other peptides had no effects. These results present direct evidence that the V3 loop of gp120 of T-tropic HIV-1 can interact with its coreceptor CXCR-4 independently of the V1/V2 regions of gp120 or cellular CD4.

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