scholarly journals Effects of Viral Strain, Transgene Position, and Target Cell Type on Replication Kinetics, Genomic Stability, and Transgene Expression of Replication-Competent Murine Leukemia Virus-Based Vectors

2007 ◽  
Vol 81 (13) ◽  
pp. 6973-6983 ◽  
Author(s):  
Matthias Paar ◽  
Sonja Schwab ◽  
Doris Rosenfellner ◽  
Brian Salmons ◽  
Walter H. Günzburg ◽  
...  
Keyword(s):  
Target Cell ◽  
Murine Leukemia Virus ◽  
Transgene Expression ◽  
Early Stage ◽  
Leukemia Virus ◽  
Genomic Stability ◽  
Retroviral Vectors ◽  
Envelope Gene ◽  
Murine Leukemia ◽  
Transgene Cassette

ABSTRACT The limited efficiency of in vivo gene transfer by replication-deficient retroviral vectors remains an obstacle to achieving effective gene therapy for solid tumors. One approach to circumvent this problem is the use of replication-competent retroviral vectors. However, the application of such vectors is at a comparatively early stage and the effects which virus strain, transgene cassette position, and target cell can exert on vector spread kinetics, genomic stability, and transgene expression levels remain to be fully elucidated. Thus, in this study a panel of vectors allowing the investigation of different design features on an otherwise genetically identical background were analyzed with respect to these readout parameters in cultures of both murine and human cells and in preformed tumors in nude mice. The obtained data revealed that (i) Moloney murine leukemia virus (Mo-MLV)-based vectors spread with faster kinetics, drive higher levels of transgene expression, and are more stable than equivalent Akv-MLV-based vectors; (ii) vectors containing the transgene cassette directly downstream of the envelope gene are genomically more stable than those containing it within the 3′-long terminal repeat U3 region; and (iii) the genomic stability of both strains seems to be cell line dependent.

Murine leukemia virus resists producer cell APOBEC3A by its Glycosylated Gag but not target cell APOBEC3A

Virology ◽  
2021 ◽  
Vol 557 ◽  
pp. 1-14 ◽  
Author(s):  
Ananda Ayyappan Jaguva Vasudevan ◽  
Kannan Balakrishnan ◽  
André Franken ◽  
Aikaterini Krikoni ◽  
Dieter Häussinger ◽  
...  
Keyword(s):  
Target Cell ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Producer Cell ◽  
Murine Leukemia

scholarly journals Bromo- and Extraterminal Domain Chromatin Regulators Serve as Cofactors for Murine Leukemia Virus Integration

2013 ◽  
Vol 87 (23) ◽  
pp. 12721-12736 ◽  
Author(s):  
Saumya Shree Gupta ◽  
Tobias Maetzig ◽  
Goedele N. Maertens ◽  
Azar Sharif ◽  
Michael Rothe ◽  
...  
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Retroviral Vectors ◽  
Transcription Start ◽  
Preintegration Complex ◽  
Transcription Start Sites ◽  
Bet Inhibitors ◽  
Murine Leukemia

Retroviral integrase (IN) proteins catalyze the permanent integration of proviral genomes into host DNA with the help of cellular cofactors. Lens epithelium-derived growth factor (LEDGF) is a cofactor for lentiviruses, including human immunodeficiency virus type 1 (HIV-1), and targets lentiviral integration toward active transcription units in the host genome. In contrast to lentiviruses, murine leukemia virus (MLV), a gammaretrovirus, tends to integrate near transcription start sites. Here, we show that the bromodomain and extraterminal domain (BET) proteins BRD2, BRD3, and BRD4 interact with gammaretroviral INs and stimulate the catalytic activity of MLV INin vitro. We mapped the interaction site to a characteristic structural feature within the BET protein extraterminal (ET) domain and to three amino acids in MLV IN. The ET domains of different BET proteins stimulate MLV integrationin vitroand, in the case of BRD2, alsoin vivo. Furthermore, two small-molecule BET inhibitors, JQ1 and I-BET, decrease MLV integration and shift it away from transcription start sites. Our data suggest that BET proteins might act as chromatin-bound acceptors for the MLV preintegration complex. These results could pave a way to redirecting MLV DNA integration as a basis for creating safer retroviral vectors.

scholarly journals Tissue- and Tumor-Specific Targeting of Murine Leukemia Virus-Based Replication-Competent Retroviral Vectors

2006 ◽  
Vol 80 (14) ◽  
pp. 7070-7078 ◽  
Author(s):  
Christian Metzl ◽  
Daniela Mischek ◽  
Brian Salmons ◽  
Walter H. Günzburg ◽  
Matthias Renner ◽  
...  
Keyword(s):  
T Cell ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Genomic Stability ◽  
Tata Box ◽  
Regulatory Sequence ◽  
Wild Type ◽  
T Cell Factor ◽  
Dividing Cells ◽  
Murine Leukemia

ABSTRACT Replication-competent retrovirus vectors based on murine leukemia virus (MLV) have been shown to effectively transfer therapeutic genes over multiple serial infections in cell culture and through solid tumors in vivo with a high degree of genomic stability. While simple retroviruses possess a natural tumor selectivity in that they can transduce only actively dividing cells, additional tumor-targeting strategies would nevertheless be advantageous, since tumor cells are not the only actively dividing cells. In this study, we used the promiscuous murine cytomegalovirus promoter, a chimeric regulatory sequence consisting of the hepatitis B virus enhancer II and the human α1-antitrypsin (EII-Pa1AT) promoter, and a synthetic regulatory sequence consisting of a series of T-cell factor binding sites named the CTP4 promoter to generate replicating MLV vectors, whereby the last two are transcriptionally restricted to liver- and β-catenin/T-cell factor-deregulated cells, respectively. When the heterologous promoters were used to replace almost the entire MLV U3 region, including the MLV TATA box, vector replication was inefficient since nascent virus particle production from infected cells was greatly decreased. Fusion of the heterologous promoters lacking the TATA box to the MLV TATA box, however, generated vectors which replicated with almost-wild-type kinetics throughout permissive cells while exhibiting low or negligible spread in nonpermissive cells. The genomic stability of the vectors was shown to be comparable to that of a similar vector containing wild-type MLV long terminal repeats, and tropism analysis over repeated infection cycles showed that the targeted vectors retained their original specificity.

scholarly journals Change of Tropism of SL3-2 Murine Leukemia Virus, Using Random Mutational Libraries

2004 ◽  
Vol 78 (17) ◽  
pp. 9343-9351 ◽  
Author(s):  
Shervin Bahrami ◽  
Mogens Duch ◽  
Finn Skou Pedersen
Keyword(s):  
Amino Acids ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Envelope Gene ◽  
Wild Type ◽  
Design And Optimization ◽  
Hydrophobic Amino Acids ◽  
Amino Acid Mutations ◽  
Library Selection ◽  
Murine Leukemia

ABSTRACT SL3-2 is a polytropic murine leukemia virus with a limited species tropism. We cloned the envelope gene of this virus, inserted it into a bicistronic vector, and found that the envelope protein differs from other, similar envelope proteins that also utilize the polytropic receptor (Xpr1) in that it is severely impaired in mediating infection of human and mink cells. We found that two adjacent amino acid mutations (G212R and I213T), located in a previously functionally uncharacterized segment of the surface subunit, are responsible for the restricted tropism of the SL3-2 wild-type envelope. By selection from a two-codon library, several hydrophobic amino acids at these positions were found to enable the SL3-2 envelope to infect human TE 671 cells. In particular, an M212/V213 mutant had a titer at least 6 orders of magnitude higher than that of the wild-type envelope for human TE 671 cells and infected human, mink, and murine cells with equal efficiencies. Notably, these two amino acids are not found at homologous positions in known murine leukemia virus isolates. Functional analysis and library selection were done on the basis of sequence and tropism analyses of the SL3-2 envelope gene. Similar approaches may be valuable in the design and optimization of retroviral envelopes with altered tropisms for biotechnological purposes.

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