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Stanislav Indik - One of the best experts on this subject based on the ideXlab platform.
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A high rate of polymerization during synthesis of mouse mammary tumor virus DNA alleviates hypermutation by APOBEC3 proteins
PLoS pathogens, 2019Co-Authors: Benedikt Hagen, Martin Kraase, Ivana Indikova, Stanislav IndikAbstract:Retroviruses have evolved multiple means to counteract host restriction factors such as single-stranded DNA-specific deoxycytidine deaminases (APOBEC3s, A3s). These include exclusion of A3s from virions by an A3-unreactive nucleocapsid or expression of an A3-neutralizing protein (Vif, Bet). However, a number of retroviruses package A3s and do not encode apparent vif- or bet-like genes, yet they replicate in the presence of A3s. The mode by which they overcome deleterious restriction remains largely unknown. Here we show that the prototypic Betaretrovirus, mouse mammary tumor virus (MMTV), packages similar amounts of A3s as HIV-1ΔVif, yet its proviruses carry a significantly lower level of A3-mediated deamination events than the lentivirus. The G-to-A mutation rate increases when the kinetics of reverse transcription is reduced by introducing a mutation (F120L) to the DNA polymerase domain of the MMTV reverse transcriptase (RT). A similar A3-sensitizing effect was observed when the exposure time of single-stranded DNA intermediates to A3s during reverse transcription was lengthened by reducing the dNTP concentration or by adding suboptimal concentrations of an RT inhibitor to infected cells. Thus, the MMTV RT has evolved to impede access of A3s to transiently exposed minus DNA strands during reverse transcription, thereby alleviating inhibition by A3 family members. A similar mechanism may be used by other retroviruses and retrotransposons to reduce deleterious effects of A3 proteins.
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single amino acid substitution g42e in the receptor binding domain of mouse mammary tumour virus envelope protein facilitates infection of non murine cells in a transferrin receptor 1 independent manner
Retrovirology, 2015Co-Authors: Constantine James Konstantoulas, Benjamin Lamp, Tillman Hans Rumenapf, Stanislav IndikAbstract:Background Mouse mammary tumour virus (MMTV) is a Betaretrovirus that infects rodent cells and uses mouse tranferrin receptor 1 (TfR1) for cell entry. Several MMTV strains have been shown to productively infect, in addition to murine cells, various heterologous cell lines including those of human origin, albeit less efficiently than murine cells. Furthermore, there have been reports that the continued passage of MMTV in heterologous cell lines gives rise to novel variants that are able to infect naive non-murine cells with higher efficiency than the parental virus.
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Frequent proviral integration of the human Betaretrovirus in biliary epithelium of patients with autoimmune and idiopathic liver disease.
Alimentary pharmacology & therapeutics, 2014Co-Authors: Weiwei Wang, Stanislav Indik, Shawn T. Wasilenko, A. Faschinger, Eric J. Carpenter, Z. Tian, Y. Zhang, Gane Ka-shu Wong, Andrew L. MasonAbstract:Summary Background A human Betaretrovirus (HBRV) has been linked with primary biliary cirrhosis (PBC) following the detection of viral particles in biliary epithelium by electron microscopy and cloning of the Betaretrovirus genome from biliary epithelium and peri-hepatic lymph nodes. Evidence for viral infection was found in the majority of PBC patients' peri-hepatic lymph node samples. However, less than a third of the liver samples had detectable HBRV, whereas others were unable to detect Betaretrovirus infection or noted the presence of virus in the liver of patients with other diagnoses. Aims To address the hypothesis that the Betaretrovirus may be below the limits of detection in the liver, biliary epithelial cells (BEC) were investigated for the evidence of infection. Methods Ligation-mediated PCR and next generation sequencing were used to detect proviral integrations in liver, lymph nodes and BEC isolated from liver transplant recipients. Hybridisation-based assays were used to detect betaretroviral RNA in BEC. Results Unique HBRV integrations and Betaretrovirus RNA were detected in the majority of biliary epithelia derived from patients with PBC, autoimmune hepatitis and cryptogenic liver disease but rarely in other liver transplant recipients with primary sclerosing cholangitis and other hepatic disorders. HBRV integrations were commonly found in PBC patients' lymph nodes but rarely in whole liver samples. Conclusions Human Betaretrovirus infection is frequently observed at the site of disease in patients with primary biliary cirrhosis and also in biliary epithelium of patients with autoimmune hepatitis and cryptogenic liver disease.
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Mouse mammary tumor virus-based vector transduces non-dividing cells, enters the nucleus via a TNPO3-independent pathway and integrates in a less biased fashion than other retroviruses
Retrovirology, 2014Co-Authors: Constantine James Konstantoulas, Stanislav IndikAbstract:Background Mouse mammary tumor virus (MMTV) is a complex, milk-born Betaretrovirus, which preferentially infects dendritic cells (DC) in the gastrointestinal tract and then spreads to T and B lymphocytes and finally to the mammary gland. It is not clear how the prototypic Betaretrovirus infects mucosal DCs and naive lymphocytes as these cells are considered to be non-proliferative. Studies of MMTV biology have been hampered by the difficulty of obtaining sufficient virus/vector titers after transfection of a molecular clone in cultured cells. To surmount this barrier we developed a novel MMTV-based vector system with a split genome design containing potent posttranscriptional regulatory functions.
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Mouse mammary tumor virus-based vector transduces non-dividing cells, enters the nucleus via a TNPO3-independent pathway and integrates in a less biased fashion than other retroviruses
Retrovirology, 2014Co-Authors: Constantine James Konstantoulas, Stanislav IndikAbstract:Background Mouse mammary tumor virus (MMTV) is a complex, milk-born Betaretrovirus, which preferentially infects dendritic cells (DC) in the gastrointestinal tract and then spreads to T and B lymphocytes and finally to the mammary gland. It is not clear how the prototypic Betaretrovirus infects mucosal DCs and naïve lymphocytes as these cells are considered to be non-proliferative. Studies of MMTV biology have been hampered by the difficulty of obtaining sufficient virus/vector titers after transfection of a molecular clone in cultured cells. To surmount this barrier we developed a novel MMTV-based vector system with a split genome design containing potent posttranscriptional regulatory functions. Results Using this system, vector particles were produced to markedly greater titers (>1000-fold) than those obtained previously. The titers (>10^6 transduction units /ml) were comparable to those achieved with lentiviral or gammaretroviral vectors. Importantly, the vector transduced the enhanced green fluorescence protein gene into the chromosomes of non-dividing cells, such as cells arrested at the G_2/M phase of the cell cycle and unstimulated hematopoietic progenitor cells, at an efficiency similar to that obtained with the HIV-1-based vector. In contrast to HIV-1, MMTV transductions were not affected by knocking down the expression of a factor involved in nuclear import of the HIV-1 pre-integration complexes, TNPO3. In contrast to HIV-1, the MMTV-based vector did not preferentially integrate in transcription units. Additionally, no preference for integration near transcription start sites, the regions preferentially targeted by gammaretroviral vectors, was observed. The vector derived from MMTV exhibits a random integration pattern. Conclusions Overall, the betaretroviral vector system should facilitate molecular virology studies of the prototypic Betaretrovirus as well as studies attempting to elucidate fundamental cellular processes such as nuclear import pathways. Random integration in cycling and non-cycling cells may be applicable in unbiased gene delivery.
Andrew L. Mason - One of the best experts on this subject based on the ideXlab platform.
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Corrigendum to "Seroprevalence of Human Betaretrovirus Surface Protein Antibodies in Patients with Breast Cancer and Liver Disease".
Journal of oncology, 2020Co-Authors: Guangzhi Zhang, Kiandokht Bashiri, Mark Kneteman, Kevan Cave, Youngkee Hong, John R. Mackey, Harvey J. Alter, Andrew L. MasonAbstract:[This corrects the article DOI: 10.1155/2020/8958192.].
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Seroprevalence of Human Betaretrovirus Surface Protein Antibodies in Patients with Breast Cancer and Liver Disease.
Journal of oncology, 2020Co-Authors: Guangzhi Zhang, Kiandokht Bashiri, Mark Kneteman, Kevan Cave, Youngkee Hong, John R. Mackey, Harvey J. Alter, Andrew L. MasonAbstract:Mouse mammary tumor virus (MMTV) is a Betaretrovirus that plays a causal role in the development of breast cancer and lymphoma in mice. Closely related sequences that share 91–99% nucleotide identity with MMTV have been repeatedly found in humans with neoplastic and inflammatory diseases. Evidence for infection with a Betaretrovirus has been found in patients with breast cancer and primary biliary cholangitis and referred to as the human mammary tumor virus and the human Betaretrovirus (HBRV), respectively. Using the gold standard technique of demonstrating retroviral infection, HBRV proviral integrations have been detected in cholangiocytes, lymph nodes, and liver of patients with primary biliary cholangitis. However, the scientific biomedical community has not embraced the hypothesis that MMTV like Betaretroviruses may infect humans because reports of viral detection have been inconsistent and robust diagnostic assays are lacking. Specifically, prior serological assays using MMTV proteins have produced divergent results in human disease. Accordingly, a partial HBRV surface (Su) construct was transfected into HEK293 to create an ELISA. The secreted HBRV gp52 Su protein was then used to screen for serological responses in patients with breast cancer and liver disease. A greater proportion of breast cancer patients (n = 98) were found to have serological reactivity to HBRV Su as compared to age- and sex-matched control subjects (10.2% versus 2.0%, , OR = 5.6 [1.25–26.3]). Similarly, the frequency of HBRV Su reactivity was higher in patients with primary biliary cholangitis (n = 156) as compared to blood donors (11.5% vs. 3.1%, , OR = 4.09 [1.66–10.1]). While the sensitivity of the HBRV Su ELISA was limited, the assay was highly specific for serologic detection in patients with breast cancer or primary biliary cholangitis, respectively (98.0% [93.1%–99.7%] and 97.0% [93.4%–98.6%]). Additional assays will be required to link immune response to Betaretrovirus infection and either breast cancer or primary biliary cholangitis.
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Randomized clinical trial: Combination antiretroviral therapy with tenofovir-emtricitabine and lopinavir-ritonavir in patients with primary biliary cholangitis
Canadian Liver Journal, 2019Co-Authors: Ellina Lytvyak, Aldo J. Montano-loza, Ishwar Hosamani, Lynora Saxinger, Andrew L. MasonAbstract:Background: Prior studies using reverse transcriptase inhibitors to treat a human Betaretrovirus (HBRV) in patients with primary biliary cholangitis (PBC) resulted in a 21% reduction in alkaline ph...
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Is PBC a viral infectious disease
Best practice & research. Clinical gastroenterology, 2018Co-Authors: Andrew L. MasonAbstract:Abstract The human Betaretrovirus and the closely related mouse mammary tumor virus have been linked with the development of cholangitis and mitochondrial antibody production in patients with primary biliary cholangitis (PBC) and mouse models of autoimmune biliary disease, respectively. In vitro, Betaretroviruses have been found to stimulate the expression of mitochondrial autoantigens on the cell surface of biliary epithelial cells. In vivo, both mitochondrial autoantigens and viral proteins have been shown to be co-expressed in biliary epithelium and lymphoid tissue. Notably, both mice and humans make poor antibody responses to Betaretrovirus infection, whereas proinflammatory responses to viral proteins have been observed in T lymphocyte studies. Furthermore, proviral integration studies have confirmed the presence of human Betaretrovirus in biliary epithelium of patients with PBC. Preliminary proof of principal studies using combination antiretroviral therapy have shown that suppression of viral expression is associated with sustained biochemical response. As the previous regimen used was poorly tolerated, further randomized controlled trials are planned to determine whether Betaretrovirus infection plays an important role in the development of PBC.
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Combination antiretroviral studies for patients with primary biliary cirrhosis
World journal of gastroenterology, 2016Co-Authors: Ellina Lytvyak, Aldo J. Montano-loza, Andrew L. MasonAbstract:Following the characterization of a human Betaretrovirus in patients with primary biliary cirrhosis (PBC), pilot studies using antiretroviral therapy have been conducted as proof of principal to establish a link of virus with disease and with the eventual aim to find better adjunct therapies for patients unresponsive to ursodeoxycholic acid. In the first open label pilot study, the reverse transcriptase inhibitor lamivudine had little demonstrable biochemical or histological effect after 1 year. Whereas, lamivudine in combination with zidovudine was associated with a significant reduction in alkaline phosphatase as well as improvement in necroinflammatory score, cholangitis and ductopenia over a 12 mo period. A double blind, multi-center randomized controlled trial using lamivudine with zidovudine for 6 mo confirmed a significant reduction in alkaline phosphatase, ALT and AST in patients on antiviral therapy. However, none of the patients achieved the stringent endpoint criteria for normalization of alkaline phosphatase. Furthermore, some patients developed biochemical rebound consistent with drug resistance. A major fault of these studies has been the inability to measure the viral load in peripheral blood and therefore, provide a direct correlation between improvement of hepatic biochemistry and reduction in viral load. Nevertheless, viral mutants to lamivudine with zidovudine were later characterized in the NOD.c3c4 mouse model of PBC that has been used to test other antiretroviral regimens to Betaretrovirus. The combination of tenofovir and emtricitabine reverse transcriptase inhibitors and the HIV protease inhibitor, lopinavir were found to abrogate cholangitis in the NOD.c3c4 mouse model and the same regimen normalized the liver tests in a PBC patient with HIV and human Betaretrovirus infection. This combination antiretroviral therapy has now been used in a double blind randomized controlled crossover study for patients with PBC followed by an open label extension study. Only a third of the PBC patients were able to tolerate the lopinavir but those maintained on tenofovir, emtricitabine and lopinavir experienced sustained and clinically meaningful reduction in hepatic biochemistry. While we await the histological and virological evaluation, it is clear that better tolerated regimens of antiretroviral treatment will be required in future clinical trials.
Tahir A. Rizvi - One of the best experts on this subject based on the ideXlab platform.
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Sequences within Both the 59 UTR and Gag Are Required for Optimal In Vivo Packaging and Propagation of Mouse Mammary Tumor Virus (MMTV) Genomic RNA
2016Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background: This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 59 untranslated region (59 UTR) and 59 end of gag constitute important packaging determinants for gRNA. Methodology: Three series of MMTV transfer vectors containing incremental amounts of gag or 59 UTR sequences, or incremental amounts of 59 UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 59 sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings: MMTV requires the entire 59 UTR and a minimum of,120 nucleotide (nt) at the 59 end of gag for no
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sequences within both the 5 utr and gag are required for optimal in vivo packaging and propagation of mouse mammary tumor virus mmtv genomic rna
PLOS ONE, 2012Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 5′ untranslated region (5′ UTR) and 5′ end of gag constitute important packaging determinants for gRNA. Methodology Three series of MMTV transfer vectors containing incremental amounts of gag or 5′ UTR sequences, or incremental amounts of 5′ UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 5′ sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings MMTV requires the entire 5′ UTR and a minimum of ∼120 nucleotide (nt) at the 5′ end of gag for not only efficient gRNA packaging but also propagation of MMTV-based transfer vector RNAs. Vector RNAs without the entire 5′ UTR were defective for both efficient packaging and propagation into target cells. Conclusions/Significance These results reveal that the 5′ end of MMTV genome is critical for both gRNA packaging and propagation, unlike the recently delineated FIV and MPMV packaging determinants that have been shown to be of bipartite nature.
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Sequences within Both the 5′ UTR and Gag Are Required for Optimal In Vivo Packaging and Propagation of Mouse Mammary Tumor Virus (MMTV) Genomic RNA
PloS one, 2012Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 5′ untranslated region (5′ UTR) and 5′ end of gag constitute important packaging determinants for gRNA. Methodology Three series of MMTV transfer vectors containing incremental amounts of gag or 5′ UTR sequences, or incremental amounts of 5′ UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 5′ sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings MMTV requires the entire 5′ UTR and a minimum of ∼120 nucleotide (nt) at the 5′ end of gag for not only efficient gRNA packaging but also propagation of MMTV-based transfer vector RNAs. Vector RNAs without the entire 5′ UTR were defective for both efficient packaging and propagation into target cells. Conclusions/Significance These results reveal that the 5′ end of MMTV genome is critical for both gRNA packaging and propagation, unlike the recently delineated FIV and MPMV packaging determinants that have been shown to be of bipartite nature.
Constantine James Konstantoulas - One of the best experts on this subject based on the ideXlab platform.
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single amino acid substitution g42e in the receptor binding domain of mouse mammary tumour virus envelope protein facilitates infection of non murine cells in a transferrin receptor 1 independent manner
Retrovirology, 2015Co-Authors: Constantine James Konstantoulas, Benjamin Lamp, Tillman Hans Rumenapf, Stanislav IndikAbstract:Background Mouse mammary tumour virus (MMTV) is a Betaretrovirus that infects rodent cells and uses mouse tranferrin receptor 1 (TfR1) for cell entry. Several MMTV strains have been shown to productively infect, in addition to murine cells, various heterologous cell lines including those of human origin, albeit less efficiently than murine cells. Furthermore, there have been reports that the continued passage of MMTV in heterologous cell lines gives rise to novel variants that are able to infect naive non-murine cells with higher efficiency than the parental virus.
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Mouse mammary tumor virus-based vector transduces non-dividing cells, enters the nucleus via a TNPO3-independent pathway and integrates in a less biased fashion than other retroviruses
Retrovirology, 2014Co-Authors: Constantine James Konstantoulas, Stanislav IndikAbstract:Background Mouse mammary tumor virus (MMTV) is a complex, milk-born Betaretrovirus, which preferentially infects dendritic cells (DC) in the gastrointestinal tract and then spreads to T and B lymphocytes and finally to the mammary gland. It is not clear how the prototypic Betaretrovirus infects mucosal DCs and naive lymphocytes as these cells are considered to be non-proliferative. Studies of MMTV biology have been hampered by the difficulty of obtaining sufficient virus/vector titers after transfection of a molecular clone in cultured cells. To surmount this barrier we developed a novel MMTV-based vector system with a split genome design containing potent posttranscriptional regulatory functions.
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Mouse mammary tumor virus-based vector transduces non-dividing cells, enters the nucleus via a TNPO3-independent pathway and integrates in a less biased fashion than other retroviruses
Retrovirology, 2014Co-Authors: Constantine James Konstantoulas, Stanislav IndikAbstract:Background Mouse mammary tumor virus (MMTV) is a complex, milk-born Betaretrovirus, which preferentially infects dendritic cells (DC) in the gastrointestinal tract and then spreads to T and B lymphocytes and finally to the mammary gland. It is not clear how the prototypic Betaretrovirus infects mucosal DCs and naïve lymphocytes as these cells are considered to be non-proliferative. Studies of MMTV biology have been hampered by the difficulty of obtaining sufficient virus/vector titers after transfection of a molecular clone in cultured cells. To surmount this barrier we developed a novel MMTV-based vector system with a split genome design containing potent posttranscriptional regulatory functions. Results Using this system, vector particles were produced to markedly greater titers (>1000-fold) than those obtained previously. The titers (>10^6 transduction units /ml) were comparable to those achieved with lentiviral or gammaretroviral vectors. Importantly, the vector transduced the enhanced green fluorescence protein gene into the chromosomes of non-dividing cells, such as cells arrested at the G_2/M phase of the cell cycle and unstimulated hematopoietic progenitor cells, at an efficiency similar to that obtained with the HIV-1-based vector. In contrast to HIV-1, MMTV transductions were not affected by knocking down the expression of a factor involved in nuclear import of the HIV-1 pre-integration complexes, TNPO3. In contrast to HIV-1, the MMTV-based vector did not preferentially integrate in transcription units. Additionally, no preference for integration near transcription start sites, the regions preferentially targeted by gammaretroviral vectors, was observed. The vector derived from MMTV exhibits a random integration pattern. Conclusions Overall, the betaretroviral vector system should facilitate molecular virology studies of the prototypic Betaretrovirus as well as studies attempting to elucidate fundamental cellular processes such as nuclear import pathways. Random integration in cycling and non-cycling cells may be applicable in unbiased gene delivery.
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Restriction of MMTV by APOBEC3
Retrovirology, 2011Co-Authors: Martin Kraase, Constantine James Konstantoulas, Stanislav IndikAbstract:Background Host cells have developed a broad range of mechanisms to counteract retroviral infection. Besides Trim5a (tripartite motif-containing protein 5alpha) and Tetherin, APOBEC3 proteins (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3), especially APOBEC3G and APOBEC3F, are major factors in the post entry inhibition of retroviruses. These proteins are incorporated into budding virions and exhibit inhibitory activity by interfering with reverse transcription and/or by deamination of cytosine to uracil in the proviral minus strand, resulting in hypermutation of the viral DNA. Mouse mammary tumor virus, MMTV, is a murine pathogen causing mammary adenocarcinomas and Tcell lymphomas in infected animals. The Betaretrovirus, which is transmitted from mother to pubs via milk, infects dendritic cells, T-cells, B-cells and mammary epithelial cells (MEC). Previous studies showed that MMTV is inhibited by mouse APOBEC3 and human APOBEC3G proteins. However, the virus is also known to replicate in cells expressing APOBEC3 proteins, suggesting a partial resistance to the APOBEC-mediated antiviral effect. Therefore, we sought to analyse the anti-MMTV activity of APOBEC3 proteins derived from various species and compare it to the antiviral activity imposed on ΔVif HIV-1.
Farah Mustafa - One of the best experts on this subject based on the ideXlab platform.
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Sequences within Both the 59 UTR and Gag Are Required for Optimal In Vivo Packaging and Propagation of Mouse Mammary Tumor Virus (MMTV) Genomic RNA
2016Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background: This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 59 untranslated region (59 UTR) and 59 end of gag constitute important packaging determinants for gRNA. Methodology: Three series of MMTV transfer vectors containing incremental amounts of gag or 59 UTR sequences, or incremental amounts of 59 UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 59 sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings: MMTV requires the entire 59 UTR and a minimum of,120 nucleotide (nt) at the 59 end of gag for no
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sequences within both the 5 utr and gag are required for optimal in vivo packaging and propagation of mouse mammary tumor virus mmtv genomic rna
PLOS ONE, 2012Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 5′ untranslated region (5′ UTR) and 5′ end of gag constitute important packaging determinants for gRNA. Methodology Three series of MMTV transfer vectors containing incremental amounts of gag or 5′ UTR sequences, or incremental amounts of 5′ UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 5′ sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings MMTV requires the entire 5′ UTR and a minimum of ∼120 nucleotide (nt) at the 5′ end of gag for not only efficient gRNA packaging but also propagation of MMTV-based transfer vector RNAs. Vector RNAs without the entire 5′ UTR were defective for both efficient packaging and propagation into target cells. Conclusions/Significance These results reveal that the 5′ end of MMTV genome is critical for both gRNA packaging and propagation, unlike the recently delineated FIV and MPMV packaging determinants that have been shown to be of bipartite nature.
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Sequences within Both the 5′ UTR and Gag Are Required for Optimal In Vivo Packaging and Propagation of Mouse Mammary Tumor Virus (MMTV) Genomic RNA
PloS one, 2012Co-Authors: Farah Mustafa, Dhuha Al Amri, Farah Al Ali, Noor Al Sari, Sarah Al Suwaidi, Preethi Jayanth, Pretty S. Philips, Tahir A. RizviAbstract:Background This study mapped regions of genomic RNA (gRNA) important for packaging and propagation of mouse mammary tumor virus (MMTV). MMTV is a type B Betaretrovirus which preassembles intracellularly, a phenomenon distinct from retroviruses that assemble the progeny virion at cell surface just before budding such as the type C human and feline immunodeficiency viruses (HIV and FIV). Studies of FIV and Mason-Pfizer monkey virus (MPMV), a type D Betaretrovirus with similar intracellular virion assembly processes as MMTV, have shown that the 5′ untranslated region (5′ UTR) and 5′ end of gag constitute important packaging determinants for gRNA. Methodology Three series of MMTV transfer vectors containing incremental amounts of gag or 5′ UTR sequences, or incremental amounts of 5′ UTR in the presence of 400 nucleotides (nt) of gag were constructed to delineate the extent of 5′ sequences that may be involved in MMTV gRNA packaging. Real time PCR measured the packaging efficiency of these vector RNAs into MMTV particles generated by co-transfection of MMTV Gag/Pol, vesicular stomatitis virus envelope glycoprotein (VSV-G Env), and individual transfer vectors into human 293T cells. Transfer vector RNA propagation was monitored by measuring transduction of target HeLaT4 cells following infection with viral particles containing a hygromycin resistance gene expression cassette on the packaged RNA. Principal Findings MMTV requires the entire 5′ UTR and a minimum of ∼120 nucleotide (nt) at the 5′ end of gag for not only efficient gRNA packaging but also propagation of MMTV-based transfer vector RNAs. Vector RNAs without the entire 5′ UTR were defective for both efficient packaging and propagation into target cells. Conclusions/Significance These results reveal that the 5′ end of MMTV genome is critical for both gRNA packaging and propagation, unlike the recently delineated FIV and MPMV packaging determinants that have been shown to be of bipartite nature.