scholarly journals Activity of a Sulfated Polysaccharide Extracted from the Red Seaweed Aghardhiella Tenera against Human Immunodeficiency Virus and Other Enveloped Viruses

1994 ◽  
Vol 5 (5) ◽  
pp. 297-303 ◽  
Author(s):  
M. Witvrouw ◽  
J. A. Este ◽  
M. Q. Mateu ◽  
D. Reymen ◽  
G. Andrei ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dextran Sulfate ◽  
Cytopathic Effect ◽  
Syncytium Formation ◽  
Sulfated Polysaccharide ◽  
Red Seaweed ◽  
Enveloped Viruses ◽  
Immunodeficiency Virus ◽  
Spectrum Activity ◽  
Hiv 1

A galactan sulfate (GS) was isolated from an aqueous extract of the red seaweed Aghardhiella tenera and partially purified. GS inhibited the cytopathic effect of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) in MT-4 cells at concentrations 10-fold higher than those required for the inhibition by dextran sulfate (MW 5000) of the cytopathic effect of HIV-1 and HIV-2 (50% inhibitory concentrations: 0.5 and 0.05 μg ml−1, respectively). GS suppressed syncytium formation between MOLT-4 cells and persistently HIV-1- or HIV-2-infected HUT-78 cells at concentrations higher than 5 μg ml−1. Like dextran sulfate (DS) and aurintricarboxylic acid (ATA), GS inhibited the binding of HIV-1 to the cells and the binding of anti-gp120 mAb to HIV-1 gp120. Like DS and ATA, GS proved active not only against HIV-1 and HIV-2 but also against other enveloped viruses, i.e. herpes-, toga-, arena-, myxo- and rhabdoviruses. GS represents a natural polysaccharide with broad-spectrum activity against a number of important viral pathogens.

Dimeric Macrocyclic Polyamines with Potent Inhibitory Activity against Human Immunodeficiency Virus

1995 ◽  
Vol 6 (5) ◽  
pp. 337-344 ◽  
Author(s):  
Y. Inouye ◽  
T. Kanamori ◽  
M. Sugiyama ◽  
T. Yoshida ◽  
T. Koike ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cytopathic Effect ◽  
Syncytium Formation ◽  
Physiological Conditions ◽  
Structure Activity ◽  
Immunodeficiency Virus ◽  
Macrocyclic Polyamines ◽  
Anti Hiv ◽  
Viral Cytopathic Effect ◽  
Potent Inhibitory Activity

The structure-activity relationships of monomeric and dimeric macrocyclic polyamines were studied in an attempt to find potent inhibitors of human immunodeficiency virus (HIV) types 1 and 2. In general, dimeric polyamines are superior as HIV inhibitors to their monomeric counterparts, and the activity of a dimer is proportional to that of its constituent monomers. For the monomeric compounds, the amount of positive charge on the monomer rings under physiological conditions was more important for anti-HIV activity than the ring size. On the basis of these findings, the 14-membered tetraamine cyclam was selected as the component of dimeric compounds with potentially high activity. Of the series of newly synthesized bicyclams, in which the monomeric cyclams were linked at each C-6 position, a compound with an aIkyI chain bridge three carbons in length was found to exhibit the maximum anti-HIV activity. For one particular strain (HIV-2GH-1), syncytium formation was inhibited by the bicyclams at a similar concentration to that required to inhibit the viral cytopathic effect.

scholarly journals A rat CD4 mutant containing the gp120-binding site mediates human immunodeficiency virus type 1 infection.

1993 ◽  
Vol 177 (4) ◽  
pp. 949-954 ◽  
Author(s):  
J H Simon ◽  
C Somoza ◽  
G A Schockmel ◽  
M Collin ◽  
S J Davis ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Gp120 Binding ◽  
Ability To Act ◽  
Immunodeficiency Virus ◽  
Inhibitory Antibodies ◽  
Hiv 1

CD4 is the primary receptor for the human immunodeficiency virus type 1 (HIV-1). Early mutational studies implicated a number of residues of CD4, centered in the region 41-59, in binding to gp120. However, further mutational analyses, together with studies using inhibitory antibodies or CD4-derived peptides, have suggested that other regions of CD4 are also involved in binding or postbinding events during infection. To resolve these ambiguities, we used rat CD4 mutants in which particular regions were replaced with the corresponding sequence of human CD4. We have previously shown that some of these are able to bind HIV-1 gp120, and here we test their ability to act as functional receptors. We find that the presence of human CD4 residues 33-62 is enough to confer efficient receptor function to rat CD4, and we conclude that it is unlikely that regions of CD4 outside this sequence are involved in specific interactions with HIV-1 during either infection or syncytium formation.

scholarly journals Differential CD4/CCR5 Utilization, gp120 Conformation, and Neutralization Sensitivity between Envelopes from a Microglia-Adapted Human Immunodeficiency Virus Type 1 and Its Parental Isolate

2001 ◽  
Vol 75 (8) ◽  
pp. 3568-3580 ◽  
Author(s):  
Julio Martı́n ◽  
Celia C. LaBranche ◽  
Francisco González-Scarano
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Luciferase Reporter ◽  
Recombinant Viruses ◽  
Amino Terminal ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) infects and induces syncytium formation in microglial cells from the central nervous system (CNS). A primary isolate (HIV-1BORI) was sequentially passaged in cultured microglia, and the isolate recovered (HIV-1BORI-15) showed high levels of fusion and replicated more efficiently in microglia (J. M. Strizki, A. V. Albright, H. Sheng, M. O'Connor, L. Perrin, and F. González-Scarano, J. Virol. 70:7654–7662, 1996). The parent and adapted viruses used CCR5 as coreceptor. Recombinant viruses demonstrated that the syncytium-inducing phenotype was associated with four amino acid differences in the V1/V2 region of the viral gp120 (J. T. C. Shieh, J. Martin, G. Baltuch, M. H. Malim, and F. González-Scarano, J. Virol. 74:693–701, 2000). We produced luciferase-reporter, env-pseudotyped viruses using plasmids containing env sequences from HIV-1BORI, HIV-1BORI-15, and the V1/V2 region of HIV-1BORI-15 in the context of HIV-1BORI env (named rBORI, rB15, and rV1V2, respectively). The pseudotypes were used to infect cells expressing various amounts of CD4 and CCR5 on the surface. In contrast to the parent recombinant, the rB15 and rV1V2 pseudotypes retained their infectability in cells expressing low levels of CD4 independent of the levels of CCR5, and they infected cells expressing CD4 with a chimeric coreceptor containing the third extracellular loop of CCR2b in the context of CCR5 or a CCR5 Δ4 amino-terminal deletion mutant. The VH-rB15 and VH-rV1V2 recombinant viruses were more sensitive to neutralization by a panel of HIV-positive sera than was VH-rBORI. Interestingly, the CD4-induced 17b epitope on gp120 was more accessible in the rB15 and rV1V2 pseudotypes than in rBORI, even before CD4 binding, and concomitantly, the rB15 and rV1V2 pseudotypes were more sensitive to neutralization with the human 17b monoclonal antibody. Adaptation to growth in microglia—cells that have reduced expression of CD4 in comparison with other cell types—appears to be associated with changes in gp120 that modify its ability to utilize CD4 and CCR5. Changes in the availability of the 17b epitope indicate that these affect conformation. These results imply that the process of adaptation to certain tissue types such as the CNS directly affects the interaction of HIV-1 envelope glycoproteins with cell surface components and with humoral immune responses.

scholarly journals Determinants of Syncytium Formation in Microglia by Human Immunodeficiency Virus Type 1: Role of the V1/V2 Domains

2000 ◽  
Vol 74 (2) ◽  
pp. 693-701 ◽  
Author(s):  
Joseph T. C. Shieh ◽  
Julio Martín ◽  
Gordon Baltuch ◽  
Michael H. Malim ◽  
Francisco González-Scarano
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Single Amino Acid ◽  
Single Amino Acid Change ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Microglia are the main reservoir for human immunodeficiency virus type 1 (HIV-1) in the central nervous system (CNS), and multinucleated giant cells, the result of fusion of HIV-1-infected microglia and brain macrophages, are the neuropathologic hallmark of HIV dementia. One potential explanation for the formation of syncytia is viral adaptation for these CD4+ CNS cells. HIV-1BORI-15, a virus adapted to growth in microglia by sequential passage in vitro, mediates high levels of fusion and replicates more efficiently in microglia and monocyte-derived-macrophages than its unpassaged parent (J. M. Strizki, A. V. Albright, H. Sheng, M. O'Connor, L. Perrin, and F. Gonzalez-Scarano, J. Virol. 70:7654–7662, 1996). Since the interaction between the viral envelope glycoprotein and CD4 and the chemokine receptor mediates fusion and plays a key role in tropism, we have analyzed the HIV-1BORI-15 env as a fusogen and in recombinant and pseudotyped viruses. Its syncytium-forming phenotype is not the result of a switch in coreceptor use but rather of the HIV-1BORI-15envelope-mediated fusion of CD4+CCR5+ cells with greater efficiency than that of its parental strain, either by itself or in the context of a recombinant virus. Genetic analysis indicated that the syncytium-forming phenotype was due to four discrete amino acid differences in V1/V2, with a single-amino-acid change between the parent and the adapted virus (E153G) responsible for the majority of the effect. Additionally, HIV-1BORI-15 env-pseudotyped viruses were less sensitive to decreases in the levels of CD4 on transfected 293T cells, leading to the hypothesis that the differences in V1/V2 alter the interaction between this envelope and CD4 or CCR5, or both. In sum, the characterization of the envelope of HIV-1BORI-15, a highly fusogenic glycoprotein with genetic determinants in V1/V2, may lead to a better understanding of the relationship between HIV replication and syncytium formation in the CNS and of the importance of this region of gp120 in the interaction with CD4 and CCR5.

scholarly journals Cystamine inhibits human immunodeficiency virus-1 replication in cord blood-derived mononuclear phagocytes and lymphocytes

Blood ◽  
1996 ◽  
Vol 88 (3) ◽  
pp. 928-933 ◽  
Author(s):  
WZ Ho ◽  
D Kaufman ◽  
L Song ◽  
JR Cutillii ◽  
SD Douglas
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cord Blood ◽  
Syncytium Formation ◽  
Mononuclear Phagocytes ◽  
Pediatric Hiv ◽  
Blue Dye ◽  
Blood Monocytes ◽  
Immunodeficiency Virus ◽  
Hiv 1

Abstract The effects of cystamine on the human immunodeficiency virus (HIV-1) expression in cord blood monocytes-derived macrophages (CBMDM) and lymphocytes were investigated. Cystamine suppressed HIV-1 expression in CBMDM and lymphocytes in a concentration-dependent fashion as determined by HIV-1 reverse transcriptase (RT) activity. This inhibitory effect of cystamine occurred with all five HIV-1 strains (both laboratory adopted and fresh isolates) tested in the study. The addition of cystamine to cultures of HIV-1 chronically infected CBMDM also suppressed 80% to 90% of RT activity in comparison with untreated controls. Cystamine also decreased HIV-1 protein expression in CBMDM as determined by indirect immunofluorescence assay. The inhibitory effects of cystamine on HIV-1 did not appear to be caused by toxicity to CBMDM or lymphocytes because there was no change in cell viability or cellular DNA synthesis as evaluated by trypan blue dye exclusion and [3H]-thymidine incorporation at doses of cystamine that inhibit the virus. HIV-1 infected CBMDM or lymphocyte cultures (without cystamine treatment) demonstrated giant syncytium formation or cytopathic effect (CPE), respectively, whereas cystamine-treated cultures lacked the giant syncytia or CPE induced by HIV-1 infection. Thus, these observations indicate that cystamine may have the potential to limit HIV-1 replication in monocytes/macrophages and lymphocytes in vivo and may represent a potentially useful compound in the treatment of pediatric HIV-1 infection and acquired immunodeficiency syndrome.

scholarly journals Formation of Syncytia Is Repressed by Tetraspanins in Human Immunodeficiency Virus Type 1-Producing Cells

2009 ◽  
Vol 83 (15) ◽  
pp. 7467-7474 ◽  
Author(s):  
Jia Weng ◽  
Dimitry N. Krementsov ◽  
Sandhya Khurana ◽  
Nathan H. Roy ◽  
Markus Thali
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT In vitro propagation studies have established that human immunodeficiency virus type 1 (HIV-1) is most efficiently transmitted at the virological synapse that forms between producer and target cells. Despite the presence of the viral envelope glycoprotein (Env) and CD4 and chemokine receptors at the respective surfaces, producer and target cells usually do not fuse with each other but disengage after the viral particles have been delivered, consistent with the idea that syncytia, at least in vitro, are not required for HIV-1 spread. Here, we tested whether tetraspanins, which are well known regulators of cellular membrane fusion processes that are enriched at HIV-1 exit sites, regulate syncytium formation. We found that overexpression of tetraspanins in producer cells leads to reduced syncytium formation, while downregulation has the opposite effect. Further, we document that repression of Env-induced cell-cell fusion by tetraspanins depends on the presence of viral Gag, and we demonstrate that fusion repression requires the recruitment of Env by Gag to tetraspanin-enriched microdomains (TEMs). However, sensitivity to fusion repression by tetraspanins varied for different viral strains, despite comparable recruitment of their Envs to TEMs. Overall, these data establish tetraspanins as negative regulators of HIV-1-induced cell-cell fusion, and they start delineating the requirements for this regulation.

scholarly journals Rational Site-Directed Mutations of the LLP-1 and LLP-2 Lentivirus Lytic Peptide Domains in the Intracytoplasmic Tail of Human Immunodeficiency Virus Type 1 gp41 Indicate Common Functions in Cell-Cell Fusion but Distinct Roles in Virion Envelope Incorporation

2003 ◽  
Vol 77 (6) ◽  
pp. 3634-3646 ◽  
Author(s):  
Vandana Kalia ◽  
Surojit Sarkar ◽  
Phalguni Gupta ◽  
Ronald C. Montelaro
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Immunodeficiency Virus ◽  
Arginine Residues ◽  
Hiv 1 ◽  
Cell Cell

ABSTRACT Two highly conserved cationic amphipathic α-helical motifs, designated lentivirus lytic peptides 1 and 2 (LLP-1 and LLP-2), have been characterized in the carboxyl terminus of the transmembrane (TM) envelope glycoprotein (Env) of lentiviruses . Although various properties have been attributed to these domains, their structural and functional significance is not clearly understood. To determine the specific contributions of the Env LLP domains to Env expression, processing, and incorporation and to viral replication and syncytium induction, site-directed LLP mutants of a primary dualtropic infectious human immunodeficiency virus type 1 (HIV-1) isolate (ME46) were examined. Substitutions were made for highly conserved arginine residues in either the LLP-1 or LLP-2 domain (MX1 or MX2, respectively) or in both domains (MX4). The HIV-1 mutants with altered LLP domains demonstrated distinct phenotypes. The LLP-1 mutants (MX1 and MX4) were replication defective and showed an average of 85% decrease in infectivity, which was associated with an evident decrease in gp41 incorporation into virions without a significant decrease in Env expression or processing in transfected 293T cells. In contrast, MX2 virus was replication competent and incorporated a full complement of Env into its virions, indicating a differential role for the LLP-1 domain in Env incorporation. Interestingly, the replication-competent MX2 virus was impaired in its ability to induce syncytia in T-cell lines. This defect in cell-cell fusion did not correlate with apparent defects in the levels of cell surface Env expression, oligomerization, or conformation. The lack of syncytium formation, however, correlated with a decrease of about 90% in MX2 Env fusogenicity compared to that of wild-type Env in quantitative luciferase-based cell-cell fusion assays. The LLP-1 mutant MX1 and MX4 Envs also exhibited an average of 80% decrease in fusogenicity. Altogether, these results demonstrate for the first time that the highly conserved LLP domains perform critical but distinct functions in Env incorporation and fusogenicity.

scholarly journals Anti-Human Immunodeficiency Virus Activity of YK-FH312 (a Betulinic Acid Derivative), a Novel Compound Blocking Viral Maturation

2001 ◽  
Vol 45 (4) ◽  
pp. 1225-1230 ◽  
Author(s):  
Taisei Kanamoto ◽  
Yoshiki Kashiwada ◽  
Kenji Kanbara ◽  
Kazuyo Gotoh ◽  
Manabu Yoshimori ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Betulinic Acid ◽  
Electron Microscopic Observation ◽  
Syncytium Formation ◽  
Inhibition Assay ◽  
Hiv Replication ◽  
Electron Microscopic ◽  
Immunodeficiency Virus ◽  
Anti Hiv ◽  
Hiv 1

ABSTRACT Betulinic acid, a triterpenoid isolated from the methyl alcohol extract of the leaves of Syzigium claviflorum, was found to have a potent inhibitory activity against human immunodeficiency virus type 1 (HIV-1). Betulinic acid derivatives were synthesized to enhance the anti-HIV activity. Among the derivatives, 3-O-(3′,3′-dimethylsuccinyl) betulinic acid, designated YK-FH312, showed the highest activity against HIV-induced cytopathic effects in HIV-1-infected MT-4 cells. To determine the step(s) of HIV replication affected by YK-FH312, a syncytium formation inhibition assay in MOLT-4/HIV-1IIIB and MOLT-4 coculture, a multinuclear-activation-of-galactosidase-indicator (MAGI) assay in MAGI-CCR5 cells, electron microscopic observation, and a time-of-addition assay were performed. In the syncytium formation inhibition assay or in the MAGI assay for de novo infection, the compound did not show inhibitory effects against HIV replication. Conversely, no virions were detected in HIV-1-infected cell cultures treated with YK-FH312 either by electron microscopic observation or by viral yield in the supernatant. In accordance with a p24 enzyme-linked immunosorbent assay of culture supernatant in the time-of-addition assay, YK-FH312 inhibited virus expression in the supernatant when it was added 18 h postinfection. However, Western blot analysis of the cells in the time-of-addition assay revealed that the production of viral proteins in the cells was not inhibited completely by YK-FH312. These results suggest that YK-FH312 might affect the step(s) of virion assembly and/or budding of virions, and this is a novel mechanism of action of an anti-HIV compound.

scholarly journals Potent and Selective Inhibitors of Human Immunodeficiency Virus Protease Structurally Related to L-694,746

1998 ◽  
Vol 9 (4) ◽  
pp. 21-27
Author(s):  
P Franchetti ◽  
P Perlini ◽  
G Abu Sheikha ◽  
L Cappellacci ◽  
M Grifantini ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cytopathic Effect ◽  
Selectivity Index ◽  
Hiv Protease ◽  
Enzyme Assays ◽  
Hiv Protease Inhibitors ◽  
Human Immunodeficiency Virus Protease ◽  
Immunodeficiency Virus ◽  
Anti Hiv ◽  
Hiv 1

A series of human immunodeficiency virus (HIV) protease inhibitors, which are analogues of N-[2( R)-hydroxy-1( S)-indanyl]-5( S)-[( tert-butyloxycarbonyl)amino]-4( S)-hydroxy-6-phenyl-2-( R)-[[4-(carboxymethoxy)phenyl]methyl]hexanamide (L-694,746), a metabolite of the anti-HIV agent L-689,502, were synthesized. In these compounds, the acetic group linked to the para position of the P1′ phenyl in the reference inhibitor was replaced either by the bioisosteric phosphonomethoxy group and its diisopropyl/dibenzyl derivatives, or the 1H-tetrazol-5-yl-methoxy group and its 1-benzyl derivative. In enzyme assays, phosphonomethoxy and tetrazolmethoxy analogues proved to be potent inhibitors of the HIV-1 protease, with IC50 values as low as 0.04 nM. When tested for anti-HIV-1 activity in cell-based assays, most of the new derivatives proved active, with benzyl derivatives being more active than their highly polar, unsubstituted counterparts. The dibenzylphosphonomethoxy analogue was the most active compound, with an EC50 value of 10 nM and a selectivity index of 20 000. When compounds were examined for their capability to reduce p24 levels in both acutely and chronically infected MT-4 and H9/IIIB cells, all of them were found to be active at concentrations close to those capable of preventing HIV-1-induced cytopathic effect.

scholarly journals Cystamine inhibits human immunodeficiency virus-1 replication in cord blood-derived mononuclear phagocytes and lymphocytes

Blood ◽  
1996 ◽  
Vol 88 (3) ◽  
pp. 928-933
Author(s):  
WZ Ho ◽  
D Kaufman ◽  
L Song ◽  
JR Cutillii ◽  
SD Douglas
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cord Blood ◽  
Syncytium Formation ◽  
Mononuclear Phagocytes ◽  
Pediatric Hiv ◽  
Blue Dye ◽  
Blood Monocytes ◽  
Immunodeficiency Virus ◽  
Hiv 1

The effects of cystamine on the human immunodeficiency virus (HIV-1) expression in cord blood monocytes-derived macrophages (CBMDM) and lymphocytes were investigated. Cystamine suppressed HIV-1 expression in CBMDM and lymphocytes in a concentration-dependent fashion as determined by HIV-1 reverse transcriptase (RT) activity. This inhibitory effect of cystamine occurred with all five HIV-1 strains (both laboratory adopted and fresh isolates) tested in the study. The addition of cystamine to cultures of HIV-1 chronically infected CBMDM also suppressed 80% to 90% of RT activity in comparison with untreated controls. Cystamine also decreased HIV-1 protein expression in CBMDM as determined by indirect immunofluorescence assay. The inhibitory effects of cystamine on HIV-1 did not appear to be caused by toxicity to CBMDM or lymphocytes because there was no change in cell viability or cellular DNA synthesis as evaluated by trypan blue dye exclusion and [3H]-thymidine incorporation at doses of cystamine that inhibit the virus. HIV-1 infected CBMDM or lymphocyte cultures (without cystamine treatment) demonstrated giant syncytium formation or cytopathic effect (CPE), respectively, whereas cystamine-treated cultures lacked the giant syncytia or CPE induced by HIV-1 infection. Thus, these observations indicate that cystamine may have the potential to limit HIV-1 replication in monocytes/macrophages and lymphocytes in vivo and may represent a potentially useful compound in the treatment of pediatric HIV-1 infection and acquired immunodeficiency syndrome.

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