scholarly journals Envelope proteins of spleen necrosis virus form infectious human immunodeficiency virus type 1 pseudotype vector particles, but fail to incorporate upon substitution of the cytoplasmic domain with that of Gibbon ape leukemia virus

2006 ◽  
Vol 87 (6) ◽  
pp. 1577-1581 ◽  
Author(s):  
Jörn Stitz ◽  
Nina Wolfrum ◽  
Christian J. Buchholz ◽  
Klaus Cichutek
Keyword(s):  
Leukemia Virus ◽  
Cell Targeting ◽  
Necrosis Virus ◽  
Packaging Cell ◽  
Immunodeficiency Virus ◽  
Spleen Necrosis Virus ◽  
Gibbon Ape Leukemia Virus ◽  
Spleen Necrosis ◽  
Hiv 1

The wild-type (wt) envelope (Env) proteins of spleen necrosis virus (SNV), together with the transmembrane (TM) protein fused to antibody domains (scFv), have been used for the generation of stable packaging cell lines releasing pseudotyped cell targeting vectors derived from SNV and Murine leukemia virus (MLV). As a first step towards assessing whether HIV-1(SNV/TM-scFv) packaging cells could be established for the production of lentiviral cell targeting vectors, it is reported here that infectious HIV-1-derived particles pseudotyped with wt SNV Env proteins could be generated. Using novel chimeric SNV-derived Env proteins encompassing wt and engineered cytoplasmic domains (C-tail) of the Gibbon ape leukemia virus (GaLV) TM protein, it was further shown that the wt C-tail not only excludes the GaLV TM protein from incorporation into HIV-1 particles, but confers this phenotype to other retroviral envelopes upon C-terminal fusion.

scholarly journals Cross-Packaging of Human Immunodeficiency Virus Type 1 Vector RNA by Spleen Necrosis Virus Proteins: Construction of a New Generation of Spleen Necrosis Virus-Derived Retroviral Vectors

2004 ◽  
Vol 78 (12) ◽  
pp. 6480-6488 ◽  
Author(s):  
Zahida Parveen ◽  
Muhammad Mukhtar ◽  
Adrienne Goodrich ◽  
Edward Acheampong ◽  
Ralph Dornburg ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Genomic Rna ◽  
Necrosis Virus ◽  
Immunodeficiency Virus ◽  
Spleen Necrosis Virus ◽  
Spleen Necrosis ◽  
New Generation ◽  
Hiv 1

ABSTRACT The ability of the nonlentiviral retrovirus spleen necrosis virus (SNV) to cross-package the genomic RNA of the distantly related human immunodeficiency virus type 1 (HIV-1) and vice versa was analyzed. Such a model may allow us to further study HIV-1 replication and pathogenesis, as well as to develop safe gene therapy vectors. Our results suggest that SNV can cross-package HIV-1 genomic RNA but with lower efficiency than HIV-1 proteins. However, HIV-1-specific proteins were unable to cross-package SNV RNA. We also constructed SNV-based gag-pol chimeric variants by replacing the SNV integrase with the HIV-1 integrase, based on multiple sequence alignments and domain analyses. These analyses revealed that there are conserved domains in all retroviral integrase open reading frames (orf), despite the divergence in the primary sequences. The transcomplementation assays suggested that SNV proteins recognized one of the chimeric variants. This demonstrated that HIV-1 integrase is functional in the SNV gag-pol orf with a lower transduction efficiency, utilizing homologous (SNV) RNA, as well as the heterologous vector RNA of HIV-1. These findings suggest that homology in the conserved sequences of the integrase protein may not be fully competent in the replacement of protein(s) from one retrovirus to another, and there are likely several other factors involved in each of the steps related to replication, integration, and infection. However, further studies to dissect the gag-pol region will be critical for understanding the mechanisms involved in the cleavage of reverse transcriptase, RNase H, and integrase. These studies should provide further insight into the design and development of novel molecular approaches to block HIV-1 replication and to construct a new generation of SNV-based vectors.

scholarly journals Primary Sequence and Secondary Structure Motifs in Spleen Necrosis Virus RU5 Confer Translational Utilization of Unspliced Human Immunodeficiency Virus Type 1 Reporter RNA

2003 ◽  
Vol 77 (22) ◽  
pp. 11973-11984 ◽  
Author(s):  
Tiffiney M. Roberts ◽  
Kathleen Boris-Lawrie
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Protein Production ◽  
Necrosis Virus ◽  
Immunodeficiency Virus ◽  
Spleen Necrosis Virus ◽  
Spleen Necrosis ◽  
Hiv 1

ABSTRACT The 5′ long terminal repeat (LTR) of spleen necrosis virus (SNV) contains a unique posttranscriptional control element that facilitates Rev/Rev-responsive element-independent expression of unspliced human immunodeficiency virus type 1 (HIV-1) gag reporter RNA. HIV-1 Gag expression is eliminated when SNV LTR is repositioned to the 3′ untranslated region or when the RU5 region is positioned in the antisense orientation. RU5 corresponds to the 5′ RNA terminus, and results presented here indicate that Gag production is sustained upon introduction of transcribed spacers that reposition SNV RU5 35 to 200 nucleotides downstream. Concordant results of deletion and point mutagenesis identified two functionally redundant and synergistic motifs (designated A and C) that are necessary and sufficient for SNV RU5 activity. Enzymatic analysis of SNV RU5 RNA structure determined that A and C correspond to stem-loop structures. Quantitative RNA and protein analysis of A and C mutants revealed that the structural integrity of A and C is necessary for protein production, and loss of function correlates with little change in steady-state level, splicing efficiency, or cytoplasmic accumulation of HIV-1 gag reporter RNA. Instead, the structural mutations eliminate cytoplasmic utilization as an mRNA template for Gag protein production. Point mutations of unpaired loop-and-bulge nucleotides that maintain the structure of A eliminate activity. The results show that the unpaired UUGU loop and U-rich bulges function together and are candidate SNV RU5 binding sites for the host cell protein(s) that directs cytoplasmic utilization of unspliced HIV-1 reporter RNA.

scholarly journals Pseudotyping Incompatibility between HIV-1 and Gibbon Ape Leukemia Virus Env Is Modulated by Vpu

2009 ◽  
Vol 84 (6) ◽  
pp. 2666-2674 ◽  
Author(s):  
Tiffany M. Lucas ◽  
Terri D. Lyddon ◽  
Paula M. Cannon ◽  
Marc C. Johnson
Keyword(s):  
Leukemia Virus ◽  
Cytoplasmic Tail ◽  
Viral Particles ◽  
Immunodeficiency Virus ◽  
Env Protein ◽  
Membrane Spanning ◽  
Gibbon Ape Leukemia Virus ◽  
Hiv 1 ◽  
Murine Leukemia

ABSTRACT The Env protein from gibbon ape leukemia virus (GaLV) has been shown to be incompatible with human immunodeficiency virus type 1 (HIV-1) in the production of infectious pseudotyped particles. This incompatibility has been mapped to the C-terminal cytoplasmic tail of GaLV Env. Surprisingly, we found that the HIV-1 accessory protein Vpu modulates this incompatibility. The infectivity of HIV-1 pseudotyped with murine leukemia virus (MLV) Env was not affected by Vpu. However, the infectivity of HIV-1 pseudotyped with an MLV Env with the cytoplasmic tail from GaLV Env (MLV/GaLV Env) was restricted 50- to 100-fold by Vpu. A Vpu mutant containing a scrambled membrane-spanning domain, VpuRD, was still able to restrict MLV/GaLV Env, but mutation of the serine residues at positions 52 and 56 completely alleviated the restriction. Loss of infectivity appeared to be caused by reduced MLV/GaLV Env incorporation into viral particles. The mechanism of this downmodulation appears to be distinct from Vpu-mediated CD4 downmodulation because Vpu-expressing cells that failed to produce infectious HIV-1 particles nonetheless continued to display robust surface MLV/GaLV Env expression. In addition, if MLV and HIV-1 were simultaneously introduced into the same cells, only the HIV-1 particle infectivity was restricted by Vpu. Collectively, these data suggest that Vpu modulates the cellular distribution of MLV/GaLV Env, preventing its recruitment to HIV-1 budding sites.

scholarly journals The 5′ RNA Terminus of Spleen Necrosis Virus Contains a Novel Posttranscriptional Control Element That Facilitates Human Immunodeficiency Virus Rev/RRE-Independent Gag Production

1999 ◽  
Vol 73 (6) ◽  
pp. 4847-4855 ◽  
Author(s):  
Melinda Butsch ◽  
Stacey Hull ◽  
Yalai Wang ◽  
Tiffiney M. Roberts ◽  
Kathleen Boris-Lawrie
Keyword(s):  
Human Immunodeficiency Virus ◽  
Leukemia Virus ◽  
Control Element ◽  
Enzyme Linked Immunosorbent Assay ◽  
Necrosis Virus ◽  
Rnase Protection ◽  
Posttranscriptional Control ◽  
Immunodeficiency Virus ◽  
Spleen Necrosis Virus ◽  
Spleen Necrosis

ABSTRACT Previous work has shown that spleen necrosis virus (SNV) long terminal repeats (LTRs) are associated with Rex/Rex-responsive element-independent expression of bovine leukemia virus RNA and supports the hypothesis that SNV RNA contains a cis-acting element that interacts with cellular Rex-like proteins. To test this hypothesis, the human immunodeficiency virus type 1 (HIV) Rev/RRE-dependent gag gene was used as a reporter to analyze various SNV sequences. Gag enzyme-linked immunosorbent assay and Western blot analyses reveal that HIV Gag production is enhanced at least 20,000-fold by the 5′ SNV LTR in COS, D17, and 293 cells. Furthermore, SNV RU5 in the sense but not the antisense orientation is sufficient to confer Rev/RRE-independent expression onto a cytomegalovirus-gag plasmid. In contrast, the SNV 3′ LTR and 3′ untranslated sequence between env and the LTR did not support Rev-independent gag expression. Quantitative RNase protection assays indicate that the SNV 5′ RNA terminus enhances cytoplasmic accumulation and polysome association of HIV unspliced and spliced transcripts. However, comparison of the absolute amounts of polysomal RNA indicates that polysome association is not sufficient to account for the significant increase in Gag production by the SNV sequences. Our analysis reveals that the SNV 5′ RNA terminus contains a unique cis-acting posttranscriptional control element that interacts with hypothetical cellular Rev-like proteins to facilitate HIV RNA transport and efficient translation.

scholarly journals Evidence that Ecotropic Murine Leukemia Virus Contamination in TZM-bl Cells Does Not Affect the Outcome of Neutralizing Antibody Assays with Human Immunodeficiency Virus Type 1

2009 ◽  
Vol 83 (16) ◽  
pp. 8289-8292 ◽  
Author(s):  
Emily J. Platt ◽  
Miroslawa Bilska ◽  
Susan L. Kozak ◽  
David Kabat ◽  
David C. Montefiori
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Line ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Murine Leukemia

ABSTRACT The TZM-bl cell line that is commonly used to assess neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) was recently reported to be contaminated with an ecotropic murine leukemia virus (MLV) (Y. Takeuchi, M. O. McClure, and M. Pizzato, J. Virol. 82:12585-12588, 2008), raising questions about the validity of results obtained with this cell line. Here we confirm this observation and show that HIV-1 neutralization assays performed with a variety of serologic reagents in a similar cell line that does not harbor MLV yield results that are equivalent to those obtained in TZM-bl cells. We conclude that MLV contamination has no measurable effect on HIV-1 neutralization when TZM-bl cells are used as targets for infection.

scholarly journals Coding Sequences Upstream of the Human Immunodeficiency Virus Type 1 Reverse Transcriptase Domain in Gag-Pol Are Not Essential for Incorporation of the Pr160gag-pol into Virus Particles

2002 ◽  
Vol 76 (7) ◽  
pp. 3221-3231 ◽  
Author(s):  
Hsu-Chen Chiu ◽  
Szu-Yung Yao ◽  
Chin-Tien Wang
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Leukemia Virus ◽  
Deletion Mutants ◽  
Coding Region ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Incorporation of the human immunodeficiency virus type 1 (HIV-1) Gag-Pol into virions is thought to be mediated by the N-terminal Gag domain via interaction with the Gag precursor. However, one recent study has demonstrated that the murine leukemia virus Pol can be incorporated into virions independently of Gag-Pol expression, implying a possible interaction between the Pol and Gag precursor. To test whether the HIV-1 Pol can be incorporated into virions on removal of the N-terminal Gag domain and to define sequences required for the incorporation of Gag-Pol into virions in more detail, a series of HIV Gag-Pol expression plasmids with various extensive deletions in the region upstream of the reverse transcriptase (RT) domain was constructed, and viral incorporation of the Gag-Pol deletion mutants was examined by cotransfecting 293T cells with a plasmid expressing Pr55 gag . Analysis indicated that deletion of the N-terminal two-thirds of the gag coding region did not significantly affect the incorporation of Gag-Pol into virions. In contrast, Gag-Pol proteins with deletions covering the capsid (CA) major homology regions and the adjacent C-terminal CA regions were impaired with respect to assembly into virions. However, Gag-Pol with sequences deleted upstream of the protease, or of the RT domain but retaining 15 N-terminal gag codons, could still be rescued into virions at a level about 20% of the wild-type level. When assayed in a nonmyristylated Gag-Pol context, all of the Gag-Pol deletion mutants were incorporated into virions at a level comparable to their myristylated counterparts, suggesting that the incorporation of the Gag-Pol deletion mutants into virions is independent of the N-terminal myristylation signal.

scholarly journals The Eukaryotic Translation Initiation Factor 4GI Is Cleaved by Different Retroviral Proteases

2003 ◽  
Vol 77 (23) ◽  
pp. 12392-12400 ◽  
Author(s):  
Enrique Álvarez ◽  
Luis Menéndez-Arias ◽  
Luis Carrasco
Keyword(s):  
Protein Synthesis ◽  
Virus Type ◽  
Leukemia Virus ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Intact Cells ◽  
Immunodeficiency Virus ◽  
Retroviral Proteases ◽  
Hiv 1

ABSTRACT The initiation factor eIF4G plays a central role in the regulation of translation. In picornaviruses, as well as in human immunodeficiency virus type 1 (HIV-1), cleavage of eIF4G by the viral protease leads to inhibition of protein synthesis directed by capped cellular mRNAs. In the present work, cleavage of both eIF4GI and eIF4GII has been analyzed by employing the proteases encoded within the genomes of several members of the family Retroviridae, e.g., Moloney murine leukemia virus (MoMLV), mouse mammary tumor virus, human T-cell leukemia virus type 1, HIV-2, and simian immunodeficiency virus. All of the retroviral proteases examined were able to cleave the initiation factor eIF4GI both in intact cells and in cell-free systems, albeit with different efficiencies. The eIF4GI hydrolysis patterns obtained with HIV-1 and HIV-2 proteases were very similar to each other but rather different from those obtained with MoMLV protease. Both eIF4GI and eIF4GII were cleaved very efficiently by the MoMLV protease. However, eIF4GII was a poor substrate for HIV proteases. Proteolytic cleavage of eIF4G led to a profound inhibition of cap-dependent translation, while protein synthesis driven by mRNAs containing internal ribosome entry site elements remained unaffected or was even stimulated in transfected cells.

scholarly journals Disruption of Human TRIM5α Antiviral Activity by Nonhuman Primate Orthologues

2005 ◽  
Vol 79 (12) ◽  
pp. 7883-7888 ◽  
Author(s):  
Lionel Berthoux ◽  
Sarah Sebastian ◽  
David M. Sayah ◽  
Jeremy Luban
Keyword(s):  
Leukemia Virus ◽  
Coiled Coil ◽  
Cyclophilin A ◽  
Susceptibility To Infection ◽  
Coiled Coil Domain ◽  
Immunodeficiency Virus ◽  
Species Specific ◽  
Hiv 1 ◽  
Modest Effect

ABSTRACT TRIM5 is a determinant of species-specific differences in susceptibility to infection by retroviruses bearing particular capsids. Human immunodeficiency virus type 1 (HIV-1) infection is blocked by the alpha isoform of macaque TRIM5 (TRIM5αrh) or by the product of the owl monkey TRIM5-cyclophilin A gene fusion (TRIMCyp). Human TRIM5α potently restricts specific strains of murine leukemia virus (N-MLV) but has only a modest effect on HIV-1. The amino termini of TRIM5 orthologues are highly conserved and possess a coiled-coil domain that promotes homomultimerization. Here we show that heterologous expression of TRIM5αrh or TRIMCyp in human cells interferes with the anti-N-MLV activity of endogenous human TRIM5α (TRIM5αhu). Deletion of the cyclophilin domain from TRIMCyp has no effect on heteromultimerization or colocalization with TRIM5αhu but prevents interference with anti-N-MLV activity. These data demonstrate that TRIM5 orthologues form heteromultimers and indicate that C-terminal extensions alter virus recognition by multimers of these proteins.

scholarly journals Cleavage of the Murine Leukemia Virus Transmembrane Env Protein by Human Immunodeficiency Virus Type 1 Protease: Transdominant Inhibition by Matrix Mutations

1998 ◽  
Vol 72 (12) ◽  
pp. 9621-9627 ◽  
Author(s):  
Rosemary E. Kiernan ◽  
Eric O. Freed
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Env Protein ◽  
Hiv 1 ◽  
Murine Leukemia

ABSTRACT We have identified mutations in the human immunodeficiency virus type 1 (HIV-1) matrix protein (MA) which block infectivity of virions pseudotyped with murine leukemia virus (MuLV) envelope (Env) glycoproteins without affecting infectivity conferred by HIV-1 Env or vesicular stomatitis virus G glycoproteins. This inhibition is very potent and displays a strong transdominant effect; infectivity is reduced more than 100-fold when wild-type and mutant molecular clones are cotransfected at a 1:1 ratio. This phenomenon is observed with both ecotropic and amphotropic MuLV Env. The MA mutations do not affect the incorporation of MuLV Env into virions. We demonstrate that in HIV-1 virions pseudotyped with MuLV Env, the HIV-1 protease (PR) efficiently catalyzes the cleavage of the p15(E) transmembrane (TM) protein to p12(E). Immunoprecipitation analysis of pseudotyped virions reveals that the mutant MA blocks this HIV-1 PR-mediated cleavage of MuLV TM. Furthermore, the transdominant inhibition exerted by the mutant MA on wild-type infectivity correlates with the relative level of p15(E) cleavage. Consistent with the hypothesis that abrogation of infectivity imposed by the mutant MA is due to inhibition of p15(E) cleavage, mutant virions are significantly more infectious when pseudotyped with a truncated p12(E) form of MuLV Env. These results indicate that HIV-1 Gag sequences can influence the viral PR-mediated processing of the MuLV TM Env protein p15(E). These findings have implications for the development of HIV-1-based retroviral vectors pseudotyped with MuLV Env, since p15(E) cleavage is essential for activating membrane fusion and virus infectivity.

scholarly journals The Nucleocapsid Domain Is Responsible for the Ability of Spleen Necrosis Virus (SNV) Gag Polyprotein To Package both SNV and Murine Leukemia Virus RNA

1999 ◽  
Vol 73 (11) ◽  
pp. 9170-9177 ◽  
Author(s):  
Jeanine L. Certo ◽  
Timur O. Kabdulov ◽  
Michelle L. Paulson ◽  
Jeffrey A. Anderson ◽  
Wei-Shau Hu
Keyword(s):  
Murine Leukemia Virus ◽  
Viral Vector ◽  
Leukemia Virus ◽  
Gene Products ◽  
Rna Packaging ◽  
Packaging Signal ◽  
Necrosis Virus ◽  
Spleen Necrosis Virus ◽  
Spleen Necrosis ◽  
Murine Leukemia

ABSTRACT Murine leukemia virus (MLV)-based vector RNA can be packaged and propagated by the proteins of spleen necrosis virus (SNV). We recently demonstrated that MLV proteins cannot support the replication of an SNV-based vector; RNA analysis revealed that MLV proteins cannot efficiently package SNV-based vector RNA. The domain in Gag responsible for the specificity of RNA packaging was identified using chimericgag-pol expression constructs. A competitive packaging system was established by generating a cell line that expresses one viral vector RNA containing the MLV packaging signal (Ψ) and another viral vector RNA containing the SNV packaging signal (E). The chimericgag-pol expression constructs were introduced into the cells, and vector titers as well as the efficiency of RNA packaging were examined. Our data confirm that Gag is solely responsible for the selection of viral RNAs. Furthermore, the nucleocapsid (NC) domain in the SNV Gag is responsible for its ability to interact with both SNV E and MLV Ψ. Replacement of the SNV NC with the MLV NC generated a chimeric Gag that could not package SNV RNA but retained its ability to package MLV RNA. A construct expressing SNV gag-MLVpol supported the replication of both MLV and SNV vectors, indicating that the gag and pol gene products from two different viruses can functionally cooperate to perform one cycle of retroviral replication. Viral titer data indicated that SNVcis-acting elements are not ideal substrates for MLVpol gene products since infectious viruses were generated at a lower efficiency. These results indicate that the nonreciprocal recognition between SNV and MLV extends beyond the Gag-RNA interaction and also includes interactions between Pol and othercis-acting elements.

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