scholarly journals Inositol hexakisphosphate (IP6) and inositol pentakisphosphate (IP5) are required for viral particle release of retroviruses belonging to the primate lentivirus genus

2020 ◽  
Author(s):  
Clifton L Ricana ◽  
Terri D Lyddon ◽  
Robert A Dick ◽  
Marc C Johnson
Keyword(s):  
Particle Production ◽  
Virus Production ◽  
Virus Release ◽  
Inositol Hexakisphosphate ◽  
Infectious Particle ◽  
Fold Reduction ◽  
Primate Lentiviruses ◽  
Hiv 1

AbstractInositol hexakisphosphate (IP6) potently stimulates HIV-1 particle assembly in vitro and infectious particle production in vivo. However, knockout cells lacking the enzyme inositol-pentakisphosphate 2-kinase (IPPK-KO), which adds the final phosphate to inositol pentakisphosphate (IP5) to produce IP6, were still able to produce infectious HIV-1 particles at a greatly reduced rate. HIV-1 in vitro assembly can also be stimulated to a lesser extent with IP5, but it was not known if IP5 could also function in promoting assembly in vivo. IPPK-KO cells expressed no detectable IP6 but elevated IP5 levels and displayed a 20-100-fold reduction in infectious particle production, correlating with lost virus release. Transient transfection of an IPPK expression vector stimulated infectious particle production and release in IPPK-KOs but not in wildtype cells. Several attempts to make an IP6 and IP5 deficient stable cell line were not successful, but transient expression of multiple inositol polyphosphate phosphatase-1 (MINPP1) into IPPK-KOs resulted in the near ablation of IP6 and IP5. Under these conditions, HIV-1 infectious particle production and virus release were essentially abolished (1000-fold reduction). However, other retroviruses including a Gammaretrovirus, a Betaretrovirus, and two non-primate Lentiviruses displayed only a modest (3-fold) reduction in infectious particle production from IPPK-KOs and were not significantly altered by expression of IPPK or MINPP1. The only other retrovirus found that showed a clear IP6/IP5 dependence was the primate (macaque) Lentivirus Simian Immunodeficiency Virus (SIV-mac), which displayed similar sensitivity to IP6/IP5 levels as HIV-1. Finally, we found that loss of IP6/IP5 in viral target cells had no effect on permissiveness to HIV-1 infection. However, because it was not possible to generate viral particles devoid of IP6 and IP5, we were not able to determine if IP6 or IP5 derived from the virus producer cells is required at additional steps beyond assembly.Author SummaryInositol hexakisphosphate (IP6) is a co-factor required for efficient production of infectious HIV-1 particles. The HIV-1 structural protein Gag forms a hexagonal lattice structure. The negatively charged IP6 sits in the middle of the hexamer and stabilizes a ring of positively charged lysines. Previously described results show that depletion of IP6 reduces, but does not eliminate, infectious virus production. This depletion was achieved through knock-out of inositol-pentakisphosphate 2-kinase (IPPK-KO), the enzyme responsible for adding the sixth and final phosphate to the molecule. Whether IP6 is required, another inositol phosphate can substitute, or IP6 is simply acting as an enhancer for virus production was unknown. Here, we show that loss of IP6 and inositol pentakisphosphate (IP5) abolishes infectious HIV-1 production from cells. We do this through a cell-based system using transiently expressed proteins to restore or deplete IP6 and IP5 in the IPPK-KO cell line. We further show that the IP6 and IP5 requirement is a feature of primate lentiviruses, but not all retroviruses, and that IP6 and IP5 is required in the producer but not the target cell for HIV-1 infection.

scholarly journals Repair of the UL21 Locus in Pseudorabies Virus Bartha Enhances the Kinetics of Retrograde, Transneuronal Infection In Vitro and In Vivo

2008 ◽  
Vol 83 (3) ◽  
pp. 1173-1183 ◽  
Author(s):  
D. Curanović ◽  
M. G. Lyman ◽  
C. Bou-Abboud ◽  
J. P. Card ◽  
L. W. Enquist
Keyword(s):  
Pseudorabies Virus ◽  
Particle Production ◽  
Neural Circuit ◽  
Neuronal Cultures ◽  
Wild Type ◽  
Infectious Particle ◽  
Viral Spread ◽  
Kinetics Of

ABSTRACT The attenuated pseudorabies virus (PRV) strain Bartha contains several characterized mutations that affect its virulence and ability to spread through neural circuits. This strain contains a small genomic deletion that abrogates anterograde spread and is widely used as a retrograde-restricted neural circuit tracer. Previous studies showed that the retrograde-directed spread of PRV Bartha is slower than that of wild-type PRV. We used compartmented neuronal cultures to characterize the retrograde defect and identify the genetic basis of the phenotype. PRV Bartha is not impaired in retrograde axonal transport, but transneuronal spread among neurons is diminished. Repair of the UL21 locus with wild-type sequence restored efficient transneuronal spread both in vitro and in vivo. It is likely that mutations in the Bartha UL21 gene confer defects that affect infectious particle production, causing a delay in spread to presynaptic neurons and amplification of infection. These events manifest as slower kinetics of retrograde viral spread in a neural circuit.

scholarly journals Maedi-visna virus Vif protein uses motifs distinct from HIV-1 Vif to bind zinc and cofactor required for A3 degradation

2020 ◽  
pp. jbc.RA120.015828
Author(s):  
Kirsten M. Knecht ◽  
Yingxia Hu ◽  
Diana Rubene ◽  
Matthew Cook ◽  
Samantha J Ziegler ◽  
...  
Keyword(s):  
Viral Infections ◽  
Zinc Ion ◽  
Binding Motif ◽  
Cytidine Deaminases ◽  
Visna Virus ◽  
Primate Lentiviruses ◽  
Maedi Visna Virus ◽  
Hiv 1

The mammalian apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3 or A3) family of cytidine deaminases restrict viral infections by mutating viral DNA and impeding reverse transcription. To overcome this antiviral activity, most lentiviruses express a viral accessory protein called Vif, which recruits A3 proteins to Cullin-RING E3 ubiquitin ligases such as Cul5 for ubiquitylation and subsequent proteasomal degradation. While Vif proteins from primate lentiviruses like HIV-1 utilize the transcription factor CBFβ as a non-canonical cofactor to stabilize the complex, maedi-visna virus (MVV) Vif hijacks cyclophilin A (CypA) instead. Since CBFβ and CypA are both highly conserved among mammals, the requirement for two different cellular cofactors suggests that these two A3-targeting Vif proteins have different biochemical and structural properties. To investigate this topic, we used a combination of in vitro biochemical assays and in vivo A3 degradation assays to study motifs required for MVV Vif to bind zinc ion, Cul5, and the cofactor CypA. Our results demonstrate that while some common motifs between HIV-1 Vif and MVV Vif are involved in recruiting Cul5, different determinants in MVV Vif are required for cofactor binding and stabilization of the E3 ligase complex, such as the zinc-binding motif and N- and C-terminal regions of the protein. Results from this study advance our understanding of the mechanism of MVV Vif recruitment of cellular factors and the evolution of lentiviral Vif proteins.

scholarly journals Strong In Vivo Inhibition of HIV-1 Replication by Nullbasic, a Tat Mutant

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Hongping Jin ◽  
Yifan Sun ◽  
Dongsheng Li ◽  
Min-Hsuan Lin ◽  
Mary Lor ◽  
...  
Keyword(s):  
Mutant Form ◽  
Mrna Levels ◽  
Functional Cure ◽  
Fold Reduction ◽  
Infected Cells ◽  
Hiv 1 ◽  
Transcription And Replication ◽  
In Cells

ABSTRACT Nullbasic is a mutant form of the HIV-1 transcriptional activator protein (Tat) that strongly inhibits HIV-1 transcription and replication in lymphocytes in vitro. To investigate Nullbasic inhibition in vivo, we employed an NSG mouse model where animals were engrafted with primary human CD4+ cells expressing a Nullbasic-ZsGreen1 (NB-ZSG) fusion protein or ZSG. NB-ZSG and ZSG were delivered by using a retroviral vector where CD4+ cells were transduced either prior to (preinfection) or following (postinfection) HIV-1 infection. The transduced cells were analyzed in vitro up to 10 days postinfection (dpi) and in vivo up to 39 dpi. Compared to ZSG, NB-ZSG strongly inhibited HIV-1 replication both in vitro and in vivo using preinfection treatment. In vitro, HIV-1 mRNA levels in cells were reduced by up to 60-fold. In vivo, HIV-1 RNA was undetectable in plasma samples during the course of the experiment, and HIV-1 mRNA levels in resident CD4+ cells in organ tissue were reduced up to 2,800-fold. Postinfection treatment of HIV-1-infected cells with NB-ZSG attenuated HIV-1 infection for up to 14 days. In vitro, a 25-fold reduction of viral mRNA in cells was observed but diminished to a <2-fold reduction by 10 dpi. In vivo, HIV-1 RNA was undetectable in plasma of NB-ZSG mice at 14 dpi but afterwards was not significantly different between NB-ZSG mice and control mice. However, we observed higher levels of CD4+ cells in NB-ZSG mice than in control mice, suggesting that NB-ZSG imparted a survival advantage to HIV-1-infected animals. IMPORTANCE HIV-1 infection is effectively controlled by antiviral therapy that inhibits virus replication and reduces viral loads below detectable levels in patients. However, therapy interruption leads to viral rebound due to latently infected cells, which serve as a source of continued viral infection. Interest in strategies leading to a functional cure for HIV-1 infection by long-term or permanent viral suppression is growing. Here, we show that a mutant form of the HIV-1 Tat protein, referred to as Nullbasic, inhibits HIV-1 transcription in infected CD4+ cells in vivo. Analysis shows that stable expression of Nullbasic in CD4+ cells could lead to durable anti-HIV-1 activity. Nullbasic, as a gene therapy candidate, could be a part of a functional-cure strategy to suppress HIV-1 transcription and replication.

scholarly journals Therapeutic Activity of an Anti-Idiotypic Antibody-Derived Killer Peptide against Influenza A Virus Experimental Infection

2008 ◽  
Vol 52 (12) ◽  
pp. 4331-4337 ◽  
Author(s):  
Giorgio Conti ◽  
Walter Magliani ◽  
Stefania Conti ◽  
Lucia Nencioni ◽  
Rossella Sgarbanti ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Inhibitory Activity ◽  
Influenza A ◽  
Particle Production ◽  
Killer Toxin ◽  
Mechanisms Of Action ◽  
Idiotypic Antibody ◽  
Hiv 1

ABSTRACT The in vitro and in vivo activities of a killer decapeptide (KP) against influenza A virus is described, and the mechanisms of action are suggested. KP represents the functional internal image of a yeast killer toxin that proved to exert antimicrobial and anti-human immunodeficiency virus type 1 (HIV-1) activities. Treatment with KP demonstrated a significant inhibitory activity on the replication of two strains of influenza A virus in different cell lines, as evaluated by hemagglutination, hemadsorption, and plaque assays. The complete inhibition of virus particle production and a marked reduction of the synthesis of viral proteins (membrane protein and hemagglutinin, in particular) were observed at a KP concentration of 4 μg/ml. Moreover, KP administered intraperitoneally at a dose of 100 μg/mice once a day for 10 days to influenza A/NWS/33 (H1N1) virus-infected mice improved the survival of the animals by 40% and significantly decreased the viral titers in their lungs. Overall, KP appears to be the first anti-idiotypic antibody-derived peptide that displays inhibitory activity and that has a potential therapeutic effect against pathogenic microorganisms, HIV-1, and influenza A virus by different mechanisms of action.

scholarly journals The Conserved Tyr176/Leu177 Motif in the α-Helix 9 of the Feline Immunodeficiency Virus Capsid Protein Is Critical for Gag Particle Assembly

Viruses ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 816
Author(s):  
César A. Ovejero ◽  
Silvia A. González ◽  
José L. Affranchino
Keyword(s):  
Feline Immunodeficiency Virus ◽  
Particle Production ◽  
Equine Infectious Anemia Virus ◽  
Particle Assembly ◽  
Immunodeficiency Virus ◽  
Immature Particle ◽  
Gag Assembly ◽  
Hiv 1

The capsid domain (CA) of the lentiviral Gag polyproteins has two distinct roles during virion morphogenesis. As a domain of Gag, it mediates the Gag–Gag interactions that drive immature particle assembly, whereas as a mature protein, it self-assembles into the conical core of the mature virion. Lentiviral CA proteins are composed of an N-terminal region with seven α-helices and a C-terminal domain (CA-CTD) formed by four α-helices. Structural studies performed in HIV-1 indicate that the CA-CTD helix 9 establishes homodimeric interactions that contribute to the formation of the hexameric Gag lattice in immature virions. Interestingly, the mature CA core also shows inter-hexameric associations involving helix 9 residues W184 and M185. The CA proteins of feline immunodeficiency virus (FIV) and equine infectious anemia virus (EIAV) exhibit, at equivalent positions in helix 9, the motifs Y176/L177 and L169/F170, respectively. In this paper, we investigated the relevance of the Y176/L177 motif for FIV assembly by introducing a series of amino acid substitutions into this sequence and studying their effect on in vivo and in vitro Gag assembly, CA oligomerization, mature virion production, and viral infectivity. Our results demonstrate that the Y176/L177 motif in FIV CA helix 9 is essential for Gag assembly and CA oligomerization. Notably, mutations converting the FIV CA Y176/L177 motif into the HIV-1 WM and EIAV FL sequences allow substantial particle production and viral replication in feline cells.

scholarly journals Inositol phosphates promote HIV-1 assembly and maturation to facilitate viral spread in human CD4+ T cells

2021 ◽  
Vol 17 (1) ◽  
pp. e1009190
Author(s):  
Gregory A. Sowd ◽  
Christopher Aiken
Keyword(s):  
T Cells ◽  
Particle Production ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Virus Production ◽  
Particle Assembly ◽  
Gag Protein ◽  
Viral Spread ◽  
Hiv 1

Gag polymerization with viral RNA at the plasma membrane initiates HIV-1 assembly. Assembly processes are inefficient in vitro but are stimulated by inositol (1,3,4,5,6) pentakisphosphate (IP5) and inositol hexakisphosphate (IP6) metabolites. Previous studies have shown that depletion of these inositol phosphate species from HEK293T cells reduced HIV-1 particle production but did not alter the infectivity of the resulting progeny virions. Moreover, HIV-1 substitutions bearing Gag/CA mutations ablating IP6 binding are noninfectious with destabilized viral cores. In this study, we analyzed the effects of cellular depletion of IP5 and IP6 on HIV-1 replication in T cells in which we disrupted the genes encoding the kinases required for IP6 generation, IP5 2-kinase (IPPK) and Inositol Polyphosphate Multikinase (IPMK). Knockout (KO) of IPPK from CEM and MT-4 cells depleted cellular IP6 in both T cell lines, and IPMK disruption reduced the levels of both IP5 and IP6. In the KO lines, HIV-1 spread was delayed relative to parental wild-type (WT) cells and was rescued by complementation. Virus release was decreased in all IPPK or IPMK KO lines relative to WT cells. Infected IPMK KO cells exhibited elevated levels of intracellular Gag protein, indicative of impaired particle assembly. IPMK KO compromised virus production to a greater extent than IPPK KO suggesting that IP5 promotes HIV-1 particle assembly in IPPK KO cells. HIV-1 particles released from infected IPPK or IPMK KO cells were less infectious than those from WT cells. These viruses exhibited partially cleaved Gag proteins, decreased virion-associated p24, and higher frequencies of aberrant particles, indicative of a maturation defect. Our data demonstrate that IP6 enhances the quantity and quality of virions produced from T cells, thereby preventing defects in HIV-1 replication.

COVID-19: Opinion in Prevention and dietary based management hypothesis

Coronaviruses ◽  
2020 ◽  
Vol 01 ◽  
Author(s):  
Ashraf Talaat Youssef
Keyword(s):  
Fatty Acids ◽  
Saturated Fatty Acids ◽  
Lung Damage ◽  
Gastric Aspirate ◽  
Enveloped Viruses ◽  
Multiple Organs ◽  
Fold Reduction ◽  
Antiviral Activities

The pandemic of COVID-19 had started in Wuhan city china in late 2019 with a subsequent worldwide spread. The viral infection can seriousely affect multiple organs mainly lungs, kidneys, heart, liver and brain and may lead to respiratory, renal, cardiac or hepatic failure.Vascular thrombosis of unexplained mechanism that may lead to widespread blood clots in multiple organs and cytokine storms that result of overstimulation of the immune system subsequent of lung damage may lead to sudden decompensation due to hypotension and more damage to liver, kidney, brain or lungs.Until now no drug had proved efficient in getting rid of the problem and controlling the pandemic mainly depends on preventive measures.Many preventive measures can be considered to prevent the worldwide spread of viral transmission. Polyunsaturated long chain fatty acids (PUFAs) and the medium chain saturated fatty acids (MCSFAs) and their corresponding monoglycerides had high antiviral activities against the enveloped viruses which reach to more than 10,000 -fold reduction in the viral titres in vitro and in vivo after testing of its gastric aspirate, and can contribute to the systemic immunity against the enveloped viruses.

scholarly journals 1592U89, a novel carbocyclic nucleoside analog with potent, selective anti-human immunodeficiency virus activity.

1997 ◽  
Vol 41 (5) ◽  
pp. 1082-1093 ◽  
Author(s):  
S M Daluge ◽  
S S Good ◽  
M B Faletto ◽  
W H Miller ◽  
M H St Clair ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Oral Bioavailability ◽  
Human Peripheral Blood ◽  
Cross Resistance ◽  
Immunodeficiency Virus ◽  
Carbocyclic Nucleoside ◽  
Hiv 1 ◽  
In Cells

1592U89, (-)-(1S,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol, is a carbocyclic nucleoside with a unique biological profile giving potent, selective anti-human immunodeficiency virus (HIV) activity. 1592U89 was selected after evaluation of a wide variety of analogs containing a cyclopentene substitution for the 2'-deoxyriboside of natural deoxynucleosides, optimizing in vitro anti-HIV potency, oral bioavailability, and central nervous system (CNS) penetration. 1592U89 was equivalent in potency to 3'-azido-3'-deoxythymidine (AZT) in human peripheral blood lymphocyte (PBL) cultures against clinical isolates of HIV type 1 (HIV-1) from antiretroviral drug-naive patients (average 50% inhibitory concentration [IC50], 0.26 microM for 1592U89 and 0.23 microM for AZT). 1592U89 showed minimal cross-resistance (approximately twofold) with AZT and other approved HIV reverse transcriptase (RT) inhibitors. 1592U89 was synergistic in combination with AZT, the nonnucleoside RT inhibitor nevirapine, and the protease inhibitor 141W94 in MT4 cells against HIV-1 (IIIB). 1592U89 was anabolized intracellularly to its 5'-monophosphate in CD4+ CEM cells and in PBLs, but the di- and triphosphates of 1592U89 were not detected. The only triphosphate found in cells incubated with 1592U89 was that of the guanine analog (-)-carbovir (CBV). However, the in vivo pharmacokinetic, distribution, and toxicological profiles of 1592U89 were distinct from and improved over those of CBV, probably because CBV itself was not appreciably formed from 1592U89 in cells or animals (<2%). The 5'-triphosphate of CBV was a potent, selective inhibitor of HIV-1 RT, with Ki values for DNA polymerases (alpha, beta, gamma, and epsilon which were 90-, 2,900-, 1,200-, and 1,900-fold greater, respectively, than for RT (Ki, 21 nM). 1592U89 was relatively nontoxic to human bone marrow progenitors erythroid burst-forming unit and granulocyte-macrophage CFU (IC50s, 110 microM) and human leukemic and liver tumor cell lines. 1592U89 had excellent oral bioavailability (105% in the rat) and penetrated the CNS (rat brain and monkey cerebrospinal fluid) as well as AZT. Having demonstrated an excellent preclinical profile, 1592U89 has progressed to clinical evaluation in HIV-infected patients.

scholarly journals G2-S16 Polyanionic Carbosilane Dendrimer Can Reduce HIV-1 Reservoir Formation by Inhibiting Macrophage Cell to Cell Transmission

2021 ◽  
Vol 22 (16) ◽  
pp. 8366
Author(s):  
Ignacio Relaño-Rodríguez ◽  
María de la Sierra Espinar-Buitrago ◽  
Vanessa Martín-Cañadilla ◽  
Rafael Gómez-Ramírez ◽  
María Ángeles Muñoz-Fernández
Keyword(s):  
T Cells ◽  
Developed Countries ◽  
Main Role ◽  
Viral Particles ◽  
Carbosilane Dendrimer ◽  
Science Community ◽  
New Compounds ◽  
Hiv 1

Human immunodeficiency virus (HIV-1) is still a major problem, not only in developing countries but is also re-emerging in several developed countries, thus the development of new compounds able to inhibit the virus, either for prophylaxis or treatment, is still needed. Nanotechnology has provided the science community with several new tools for biomedical applications. G2-S16 is a polyanionic carbosilane dendrimer capable of inhibiting HIV-1 in vitro and in vivo by interacting directly with viral particles. One of the main barriers for HIV-1 eradication is the reservoirs created in primoinfection. These reservoirs, mainly in T cells, are untargetable by actual drugs or immune system. Thus, one approach is inhibiting HIV-1 from reaching these reservoir cells. In this context, macrophages play a main role as they can deliver viral particles to T cells establishing reservoirs. We showed that G2-S16 dendrimer is capable of inhibiting the infection from infected macrophages to healthy T CD4/CD8 lymphocytes by eliminating HIV-1 infectivity inside macrophages, so they are not able to carry infectious particles to other body locations, thus preventing the reservoirs from forming.

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