scholarly journals Properties of human foamy virus relevant to its development as a vector for gene therapy

1999 ◽  
Vol 80 (8) ◽  
pp. 2003-2009 ◽  
Author(s):  
Claire L. Hill ◽  
Paul D. Bieniasz ◽  
Myra O. McClure
Keyword(s):  
Gene Therapy ◽  
Cell Biology ◽  
Foamy Virus ◽  
Reverse Transcriptase Activity ◽  
Virus Infectivity ◽  
Human Foamy Virus ◽  
Virus Particles ◽  
Foamy Viruses ◽  
Vesicular Stomatitis

The Spumaviridae (foamy viruses) are increasingly being considered as potential vectors for gene therapy, yet little has been documented of their basic cell biology. This study demonstrates that human foamy virus (HFV) has a broad tropism and that the receptor for HFV is expressed not only on many mammalian, but on avian and reptilian cells. Receptor interference assays using an envelope-expressing cell line and a vesicular stomatitis virus/HFV pseudotype virus demonstrate that the cellular receptor is common to all primate members of the genus. The majority of foamy virus particles assemble and remain sequestered intracellularly. A rapid and quantitative method of assaying foamy virus infectivity by reverse transcriptase activity facilitates the use of classical protocols to increase infectious virus titres in vitro to ⩾106 TCID/ml.

scholarly journals RNA and Protein Requirements for Incorporation of the Pol Protein into Foamy Virus Particles

2005 ◽  
Vol 79 (11) ◽  
pp. 7005-7013 ◽  
Author(s):  
Katrin Peters ◽  
Tatiana Wiktorowicz ◽  
Martin Heinkelein ◽  
Axel Rethwilm
Keyword(s):  
Foamy Virus ◽  
Genomic Rna ◽  
Rna Packaging ◽  
Gag Protein ◽  
Protein Precursor ◽  
Protein Requirements ◽  
Virus Particles ◽  
Foamy Viruses ◽  
Protein Incorporation ◽  
The Individual

ABSTRACT Foamy viruses (FVs) generate their Pol protein precursor molecule independently of the Gag protein from a spliced mRNA. This mode of expression raises the question of the mechanism of Pol protein incorporation into the viral particle (capsid). We previously showed that the packaging of (pre)genomic RNA is essential for Pol encapsidation (M. Heinkelein, C. Leurs, M. Rammling, K. Peters, H. Hanenberg, and A. Rethwilm, J. Virol. 76:10069-10073, 2002). Here, we demonstrate that distinct sequences in the RNA, which we termed Pol encapsidation sequences (PES), are required to incorporate Pol protein into the FV capsid. Two PES were found, which are contained in the previously identified cis-acting sequences necessary to transfer an FV vector. One PES is located in the U5 region of the 5′ long terminal repeat and one at the 3′ end of the pol gene region. Neither element has any significant effect on RNA packaging. However, deletion of either PES resulted in a significant reduction in Pol encapsidation. On the protein level, we show that only the Pol precursor, but not the individual reverse transcriptase (RT) and integrase (IN) subunits, is incorporated into FV particles. However, enzymatic activities of the protease (PR), RT, or IN are not required. Our results strengthen the view that in FVs, (pre)genomic RNA functions as a bridging molecule between Gag and Pol precursor proteins.

scholarly journals Sequences in pol Are Required for Transfer of Human Foamy Virus-Based Vectors

1998 ◽  
Vol 72 (7) ◽  
pp. 5510-5516 ◽  
Author(s):  
Otto Erlwein ◽  
Paul D. Bieniasz ◽  
Myra O. McClure
Keyword(s):  
Cell Lines ◽  
Foamy Virus ◽  
Infectious Clone ◽  
Helper Virus ◽  
Kidney Cells ◽  
Human Foamy Virus ◽  
Vector Systems ◽  
Sequence Requirements ◽  
Baby Hamster Kidney Cells

ABSTRACT A series of vectors with heterologous genes was constructed from HSRV1, an infectious clone of human foamy virus (HFV), and transfected into baby hamster kidney cells to generate stably transfected vector cell lines. Two cis-acting sequences were required to achieve efficient rescue by helper virus. The first element was located at the 5′ end upstream of position 1274 of the proviral DNA. Interestingly, a mutation in the leader sequence which decreased the ability to dimerize in vitro inhibited transfer by helper HFV. A second element that was important for vector transfer was located in thepol gene between positions 5638 and 6317. Constructs lacking this element were only poorly transferred by helper HFV, even though their RNA was produced in the vector cell lines. This finding rules out the possibility that the observed lack of transfer was due to RNA instability. A minimal vector containing only these two elements could be successfully delivered by helper HFV, confirming that all essential cis-acting sequences were present. The presence of a sequence described as a second polypurine tract in HFV was not necessary for transfer. Our data identified the minimal sequence requirements for HFV vector transfer for the development of useful vector systems.

scholarly journals Acetylation of the foamy virus transactivator Tas by PCAF augments promoter-binding affinity and virus transcription

2007 ◽  
Vol 88 (1) ◽  
pp. 259-263 ◽  
Author(s):  
Jochen Bodem ◽  
Hans-Georg Kräusslich ◽  
Axel Rethwilm
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Foamy Virus ◽  
Effective Means ◽  
Histone Acetyltransferases ◽  
Virus Transcription ◽  
Foamy Viruses ◽  
Direct Gene

It was shown recently that retrovirus transactivators interact with transcriptional coactivators, such as histone acetyltransferases (HATs). Foamy viruses (FVs) direct gene expression from the long terminal repeat and from an internal promoter. The activity of both promoters is strictly dependent on the DNA-binding transactivator Tas. Recently, it was shown that Tas interacts with the HATs p300 and PCAF. Based on these findings, it is demonstrated here that PCAF has the ability to acetylate Tas in vitro and in vivo. Tas acetylation resulted in enhanced DNA binding to the virus promoters. In vitro transcription reactions on non-chromatinized template showed that only acetylated Tas enhanced transcription significantly. These results demonstrate that acetylation of the FV transactivator Tas may be an effective means to regulate virus transcription.

A New Indicator Cell Line to Monitor Human Foamy Virus Infection and Stability in vitro

Intervirology ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 79-84 ◽  
Author(s):  
Zhi Li ◽  
Ping Yang ◽  
Hui Liu ◽  
Wen-xin Li
Keyword(s):  
Virus Infection ◽  
Cell Line ◽  
Foamy Virus ◽  
Human Foamy Virus ◽  
Indicator Cell Line ◽  
Indicator Cell

In vitro studies on interferoninducing capacity and sensitivity to IFN of human foamy virus

1996 ◽  
Vol 147 (1) ◽  
pp. 29-37 ◽  
Author(s):  
A. Sabile ◽  
A. Rhodes-Feuillette ◽  
F.Z. Jaoui ◽  
J. Tobaly-Tapiero ◽  
M.L. Giron ◽  
...  
Keyword(s):  
Foamy Virus ◽  
In Vitro Studies ◽  
Human Foamy Virus

scholarly journals Role of the C Terminus of Foamy Virus Gag in RNA Packaging and Pol Expression

2004 ◽  
Vol 78 (17) ◽  
pp. 9423-9430 ◽  
Author(s):  
Carolyn R. Stenbak ◽  
Maxine L. Linial
Keyword(s):  
Foamy Virus ◽  
Nucleic Acid Binding ◽  
Rna Packaging ◽  
Binding Properties ◽  
Gag Protein ◽  
C Terminus ◽  
Foamy Viruses ◽  
The Matrix

ABSTRACT Foamy viruses (FV) are complex retroviruses that possess several unique features that distinguish them from all other retroviruses. FV Gag and Pol proteins are expressed independently of one another, and both proteins undergo single cleavage events. Thus, the mature FV Gag protein does not consist of the matrix, capsid, and nucleocapsid (NC) proteins found in orthoretroviruses, and the putative NC domain of FV Gag lacks the hallmark Cys-His motifs or I domains. As there is no Gag-Pol fusion protein, the mechanism of Pol packaging is different but unknown. FV RNA packaging is not well understood either. The C terminus of FV Gag has three glycine-arginine motifs (GR boxes), the first of which has been shown to have nucleic acid binding properties in vitro. The role of these GR boxes in RNA packaging and Pol packaging was investigated with a series of Gag C-terminal truncation mutants. GR box 1 was found to be the major determinant of RNA packaging, but all three GR boxes were required to achieve wild-type levels of RNA packaging. In addition, Pol was packaged in the absence of GR box 3, but GR boxes 1 and 2 were required for efficient Pol packaging. Interestingly, the Gag truncation mutants demonstrated decreased Pol expression levels as well as defects in Pol cleavage. Thus, the C terminus of FV Gag was found to be responsible for RNA packaging, as well as being involved in the expression, cleavage, and incorporation of the Pol protein.

scholarly journals The Carboxy-Terminal p3GagDomain of the Human Foamy Virus Gag Precursor Is Required for Efficient Virus Infectivity

Virology ◽  
1998 ◽  
Vol 247 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Motomi Zemba ◽  
Thomas Wilk ◽  
Twan Rutten ◽  
Andrea Wagner ◽  
Rolf M. Flügel ◽  
...  
Keyword(s):  
Foamy Virus ◽  
Virus Infectivity ◽  
Human Foamy Virus ◽  
Carboxy Terminal

scholarly journals PEGylation of a Vesicular Stomatitis Virus G Pseudotyped Lentivirus Vector Prevents Inactivation in Serum

2004 ◽  
Vol 78 (2) ◽  
pp. 912-921 ◽  
Author(s):  
Maria A. Croyle ◽  
Shellie M. Callahan ◽  
Alberto Auricchio ◽  
Gregg Schumer ◽  
Klause D. Linse ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Vesicular Stomatitis Virus ◽  
Transduction Efficiency ◽  
Virus Particles ◽  
Pharmacokinetic Profiles ◽  
Vesicular Stomatitis ◽  
Poly Ethylene ◽  
Lentivirus Vectors

ABSTRACT One disadvantage of vesicular stomatitis virus G (VSV-G) pseudotyped lentivirus vectors for clinical application is inactivation of the vector by human serum complement. To prevent this, monomethoxypoly(ethylene) glycol was conjugated to a VSV-G-human immunodeficiency virus vector expressing Escherichia coli beta-galactosidase. The modification did not affect transduction efficiency in vitro and protected the vector from inactivation in complement-active human and mouse sera. Blood from mice dosed intravenously with either the unmodified or the PEGylated virus particles was assayed for active vector by a limiting-dilution assay to evaluate transduction efficiency and for p24, an indicator of the total number of virus particles present. PEGylation extended the circulation half-life of active vector by a factor of 5 and reduced the rate of vector inactivation in the serum by a factor of 1,000. Pharmacokinetic profiles for the total number of virus particles present in the circulation were unaffected by PEGylation. Modification of the vector with poly(ethylene) glycol significantly enhanced transduction efficiency in the bone marrow and in the spleen 14 days after systemic administration of the virus. These results, in concert with the pharmacokinetic profiles, indicate that PEGylation does protect the virus from inactivation in the serum and, as a result, improves the transduction efficiency of VSV-G pseudotyped lentivirus vectors in susceptible organs in vivo.

scholarly journals Cholesterol-modifying drugs in COVID-19

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Nathalie M Schmidt ◽  
Peter A C Wing ◽  
Jane A McKeating ◽  
Mala K Maini
Keyword(s):  
Immune Cell ◽  
Inflammatory Responses ◽  
The Elderly ◽  
Virus Infectivity ◽  
In Vivo Models ◽  
Virus Particles ◽  
Enveloped Virus ◽  
Poor Outcomes

Abstract Infection with severe acute respiratory syndrom coronavirus 2 (SARS-CoV-2) is more likely to lead to poor outcomes in the elderly and those with cardiovascular disease, obesity or metabolic syndrome. Here, we consider mechanisms by which dyslipidaemia and the use of cholesterol-modifying drugs could influence the virus–host relationship. Cholesterol is essential for the assembly, replication and infectivity of enveloped virus particles; we highlight several cholesterol-modifying drugs with the potential to alter the SARS-CoV-2 life cycle that could be tested in in vitro and in vivo models. Although cholesterol is an essential component of immune cell membranes, excess levels can dysregulate protective immunity and promote exaggerated pulmonary and systemic inflammatory responses. Statins block the production of multiple sterols, oxysterols and isoprenoids, resulting in a pleiotropic range of context-dependent effects on virus infectivity, immunity and inflammation. We highlight antiviral, immunomodulatory and anti-inflammatory effects of cholesterol-modifying drugs that merit further consideration in the management of SARS-CoV-2 infection.

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