Complete bibliography at Google Scholar
2013
Monette, Anne; Valiente-Echeverría, Fernando; Rivero, Matias; Cohen, Éric A; Lopez-Lastra, Marcelo; Mouland, Andrew J
Dual mechanisms of translation initiation of the full-length HIV-1 mRNA contribute to gag synthesis Journal Article
In: PLoS One, vol. 8, no. 7, pp. e68108, 2013, ISSN: 1932-6203.
@article{pmid23861855,
title = {Dual mechanisms of translation initiation of the full-length HIV-1 mRNA contribute to gag synthesis},
author = {Anne Monette and Fernando Valiente-Echeverría and Matias Rivero and Éric A Cohen and Marcelo Lopez-Lastra and Andrew J Mouland},
doi = {10.1371/journal.pone.0068108},
issn = {1932-6203},
year = {2013},
date = {2013-01-01},
journal = {PLoS One},
volume = {8},
number = {7},
pages = {e68108},
abstract = {The precursor group-specific antigen (pr55(Gag)) is central to HIV-1 assembly. Its expression alone is sufficient to assemble into virus-like particles. It also selects the genomic RNA for encapsidation and is involved in several important virus-host interactions for viral assembly and restriction, making its synthesis essential for aspects of viral replication. Here, we show that the initiation of translation of the HIV-1 genomic RNA is mediated through both a cap-dependent and an internal ribosome entry site (IRES)-mediated mechanisms. In support of this notion, pr55(Gag) synthesis was maintained at 70% when cap-dependent translation initiation was blocked by the expression of eIF4G- and PABP targeting viral proteases in two in vitro systems and in HIV-1-expressing cells directly infected with poliovirus. While our data reveal that IRES-dependent translation of the viral genomic RNA ensures pr55(Gag) expression, the synthesis of other HIV-1 proteins, including that of pr160(Gag/Pol), Vpr and Tat is suppressed early during progressive poliovirus infection. The data presented herein implies that the unspliced HIV-1 genomic RNA utilizes both cap-dependent and IRES-dependent translation initiation to supply pr55(Gag) for virus assembly and production.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The precursor group-specific antigen (pr55(Gag)) is central to HIV-1 assembly. Its expression alone is sufficient to assemble into virus-like particles. It also selects the genomic RNA for encapsidation and is involved in several important virus-host interactions for viral assembly and restriction, making its synthesis essential for aspects of viral replication. Here, we show that the initiation of translation of the HIV-1 genomic RNA is mediated through both a cap-dependent and an internal ribosome entry site (IRES)-mediated mechanisms. In support of this notion, pr55(Gag) synthesis was maintained at 70% when cap-dependent translation initiation was blocked by the expression of eIF4G- and PABP targeting viral proteases in two in vitro systems and in HIV-1-expressing cells directly infected with poliovirus. While our data reveal that IRES-dependent translation of the viral genomic RNA ensures pr55(Gag) expression, the synthesis of other HIV-1 proteins, including that of pr160(Gag/Pol), Vpr and Tat is suppressed early during progressive poliovirus infection. The data presented herein implies that the unspliced HIV-1 genomic RNA utilizes both cap-dependent and IRES-dependent translation initiation to supply pr55(Gag) for virus assembly and production. Valiente-Echeverría, Fernando; Vallejos, Maricarmen; Monette, Anne; Pino, Karla; Letelier, Alejandro; Huidobro-Toro, J Pablo; Mouland, Andrew J; López-Lastra, Marcelo
A cis-acting element present within the Gag open reading frame negatively impacts on the activity of the HIV-1 IRES Journal Article
In: PLoS One, vol. 8, no. 2, pp. e56962, 2013, ISSN: 1932-6203.
@article{pmid23451120,
title = {A cis-acting element present within the Gag open reading frame negatively impacts on the activity of the HIV-1 IRES},
author = {Fernando Valiente-Echeverría and Maricarmen Vallejos and Anne Monette and Karla Pino and Alejandro Letelier and J Pablo Huidobro-Toro and Andrew J Mouland and Marcelo López-Lastra},
doi = {10.1371/journal.pone.0056962},
issn = {1932-6203},
year = {2013},
date = {2013-01-01},
journal = {PLoS One},
volume = {8},
number = {2},
pages = {e56962},
abstract = {Translation initiation from the human immunodeficiency virus type-1 (HIV-1) mRNA can occur through a cap or an IRES dependent mechanism. Cap-dependent translation initiation of the HIV-1 mRNA can be inhibited by the instability element (INS)-1, a cis-acting regulatory element present within the gag open reading frame (ORF). In this study we evaluated the impact of the INS-1 on HIV-1 IRES-mediated translation initiation. Using heterologous bicistronic mRNAs, we show that the INS-1 negatively impact on HIV-1 IRES-driven translation in in vitro and in cell-based experiments. Additionally, our results show that the inhibitory effect of the INS-1 is not general to all IRESes since it does not hinder translation driven by the HCV IRES. The inhibition by the INS-1 was partially rescued in cells by the overexpression of the viral Rev protein or hnRNPA1.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Translation initiation from the human immunodeficiency virus type-1 (HIV-1) mRNA can occur through a cap or an IRES dependent mechanism. Cap-dependent translation initiation of the HIV-1 mRNA can be inhibited by the instability element (INS)-1, a cis-acting regulatory element present within the gag open reading frame (ORF). In this study we evaluated the impact of the INS-1 on HIV-1 IRES-mediated translation initiation. Using heterologous bicistronic mRNAs, we show that the INS-1 negatively impact on HIV-1 IRES-driven translation in in vitro and in cell-based experiments. Additionally, our results show that the inhibitory effect of the INS-1 is not general to all IRESes since it does not hinder translation driven by the HCV IRES. The inhibition by the INS-1 was partially rescued in cells by the overexpression of the viral Rev protein or hnRNPA1.2012
Valiente-Echeverría, Fernando; Melnychuk, Luca; Mouland, Andrew J
Viral modulation of stress granules Journal Article
In: Virus Res, vol. 169, no. 2, pp. 430–437, 2012, ISSN: 1872-7492.
@article{pmid22705970,
title = {Viral modulation of stress granules},
author = {Fernando Valiente-Echeverría and Luca Melnychuk and Andrew J Mouland},
doi = {10.1016/j.virusres.2012.06.004},
issn = {1872-7492},
year = {2012},
date = {2012-11-01},
journal = {Virus Res},
volume = {169},
number = {2},
pages = {430--437},
abstract = {Following viral infection, the host responds by mounting a robust anti-viral response with the aim of creating an unfavorable environment for viral replication. As a countermeasure, viruses have elaborated mechanisms to subvert the host response in order to maintain viral protein synthesis and production. In the last decade, several reports have shown that viruses modulate the assembly of stress granules (SGs), which are translationally silent ribonucleoproteins (RNPs) and sites of RNA triage. This review discusses recent advances in our understanding of the interactions between viruses and the host response and how virus-induced modulations in SG abundance play fundamental roles in dictating the success of viral replication.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Following viral infection, the host responds by mounting a robust anti-viral response with the aim of creating an unfavorable environment for viral replication. As a countermeasure, viruses have elaborated mechanisms to subvert the host response in order to maintain viral protein synthesis and production. In the last decade, several reports have shown that viruses modulate the assembly of stress granules (SGs), which are translationally silent ribonucleoproteins (RNPs) and sites of RNA triage. This review discusses recent advances in our understanding of the interactions between viruses and the host response and how virus-induced modulations in SG abundance play fundamental roles in dictating the success of viral replication. López, Javier; Abarca, Katia; Mundaca, M Isabel; Caballero, Carla; Valiente-Echeverría, Fernando
[Molecular identification of Ehrlichia canis in a dog from Arica, Chile] Journal Article
In: Rev Chilena Infectol, vol. 29, no. 5, pp. 527–530, 2012, ISSN: 0716-1018.
@article{pmid23282495,
title = {[Molecular identification of Ehrlichia canis in a dog from Arica, Chile]},
author = {Javier López and Katia Abarca and M Isabel Mundaca and Carla Caballero and Fernando Valiente-Echeverría},
doi = {10.4067/S0716-10182012000600008},
issn = {0716-1018},
year = {2012},
date = {2012-10-01},
journal = {Rev Chilena Infectol},
volume = {29},
number = {5},
pages = {527--530},
abstract = {We report a molecular confirmed case of canine ehrlichiosis caused by Ehrlichia canis. A 10-year old female crossbred Siberian from the city of Arica, which was infested by ticks, presented hemorrhagic manifestations (hematomas and snout bleeding) and prostration. Blood cell count revealed thrombocytopenia (30,000 platelets/ mm³). Immunochromatographic rapid testing for E. canis IgG was positive. Amplification and sequencing of a fragment of the 16S rRNA gen from a blood sample showed 100% homology with E. canis from Perú. This is the first report of E. canis in Chile, an agent with known zoonotic potential.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report a molecular confirmed case of canine ehrlichiosis caused by Ehrlichia canis. A 10-year old female crossbred Siberian from the city of Arica, which was infested by ticks, presented hemorrhagic manifestations (hematomas and snout bleeding) and prostration. Blood cell count revealed thrombocytopenia (30,000 platelets/ mm³). Immunochromatographic rapid testing for E. canis IgG was positive. Amplification and sequencing of a fragment of the 16S rRNA gen from a blood sample showed 100% homology with E. canis from Perú. This is the first report of E. canis in Chile, an agent with known zoonotic potential. López, Javier; Valiente-Echeverría, Fernando; Carrasco, Marcela; Mercado, Rubén; Abarca, Katia
[Morphological and molecular identification of canine filariae in a semi-rural district of the Metropolitan Region in Chile] Journal Article
In: Rev Chilena Infectol, vol. 29, no. 3, pp. 248–289, 2012, ISSN: 0717-6341.
@article{pmid23096462,
title = {[Morphological and molecular identification of canine filariae in a semi-rural district of the Metropolitan Region in Chile]},
author = {Javier López and Fernando Valiente-Echeverría and Marcela Carrasco and Rubén Mercado and Katia Abarca},
doi = {10.4067/S0716-10182012000300006},
issn = {0717-6341},
year = {2012},
date = {2012-06-01},
journal = {Rev Chilena Infectol},
volume = {29},
number = {3},
pages = {248--289},
abstract = {INTRODUCTION: To date, there has been no definitive confirmation of the presence of zoonotic dirofilariasis in dogs in Chile.
OBJECTIVES: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations.
METHODS: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified.
CONCLUSIONS: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
INTRODUCTION: To date, there has been no definitive confirmation of the presence of zoonotic dirofilariasis in dogs in Chile.
OBJECTIVES: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations.
METHODS: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified.
CONCLUSIONS: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.2011
C, Juan C Flores; A, Cecilia Vizcaya; B, Rafael Araos; P, Luisa Montecinos; M, Paula Godoy; Valiente-Echeverría, Fernando; P, Cecilia Perret; C, Patricia Valenzuela; B, Tamara Hirsch; G, Marcela Ferrés
[Human bocavirus in Chile: clinical characteristics and epidemiological profile in children with acute respiratory tract infections] Journal Article
In: Rev Chilena Infectol, vol. 28, no. 6, pp. 504–511, 2011, ISSN: 0716-1018.
@article{pmid22286672,
title = {[Human bocavirus in Chile: clinical characteristics and epidemiological profile in children with acute respiratory tract infections]},
author = {Juan C Flores C and Cecilia Vizcaya A and Rafael Araos B and Luisa Montecinos P and Paula Godoy M and Fernando Valiente-Echeverría and Cecilia Perret P and Patricia Valenzuela C and Tamara Hirsch B and Marcela Ferrés G},
issn = {0716-1018},
year = {2011},
date = {2011-12-01},
journal = {Rev Chilena Infectol},
volume = {28},
number = {6},
pages = {504--511},
abstract = {BACKGROUND: Human bocavirus (HBoV) is a newly discovered parvovirus found in children with acute respiratory tract infections (ARTI).
OBJECTIVES: To describe the epidemiological and clinical profile of children < 5 years old consulting for ARTI, comparing cases of HBoV monoinfection and coinfection with other known respiratory viruses. Furthermore, we aimed to estimate the prevalence of viral shedding in asymptomatic children and perform phylogenetic analysis.
PATIENTS AND METHODS: We investigated the presence of HBoV in nasopharyngeal secretions from children consulting for AlRTI and among asymptomatic controls, between 2007 and 2008, by polymerase chain reaction.
RESULTS: HBoV was detected in 79 (21.8%) of 362 nasopharyngeal swabs obtained from children with ARTI. In 60/79 (76%), coinfection with other respiratory viruses was confirmed. Most common symptoms were cough, fever and rhinorrhea. Children infected only with HBoV showed significantly lower frequencies of respiratory distress, oxygen requirements and hospital admission than those with coinfection. HBoV was detected in 6/16 (37.5%) samples from asymptomatic children. The phylogenetic analysis of viruses from Chilean patients revealed that circulating HBoV was closely related to original strains.
CONCLUSIONS: HBoV was found either in symptomatic and asymptomatic children. The severity of the disease was greater when HBoV was associated to other respiratory viruses.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Human bocavirus (HBoV) is a newly discovered parvovirus found in children with acute respiratory tract infections (ARTI).
OBJECTIVES: To describe the epidemiological and clinical profile of children < 5 years old consulting for ARTI, comparing cases of HBoV monoinfection and coinfection with other known respiratory viruses. Furthermore, we aimed to estimate the prevalence of viral shedding in asymptomatic children and perform phylogenetic analysis.
PATIENTS AND METHODS: We investigated the presence of HBoV in nasopharyngeal secretions from children consulting for AlRTI and among asymptomatic controls, between 2007 and 2008, by polymerase chain reaction.
RESULTS: HBoV was detected in 79 (21.8%) of 362 nasopharyngeal swabs obtained from children with ARTI. In 60/79 (76%), coinfection with other respiratory viruses was confirmed. Most common symptoms were cough, fever and rhinorrhea. Children infected only with HBoV showed significantly lower frequencies of respiratory distress, oxygen requirements and hospital admission than those with coinfection. HBoV was detected in 6/16 (37.5%) samples from asymptomatic children. The phylogenetic analysis of viruses from Chilean patients revealed that circulating HBoV was closely related to original strains.
CONCLUSIONS: HBoV was found either in symptomatic and asymptomatic children. The severity of the disease was greater when HBoV was associated to other respiratory viruses. Vallejos, Maricarmen; Deforges, Jules; Plank, Terra-Dawn M; Letelier, Alejandro; Ramdohr, Pablo; Abraham, Christopher G; Valiente-Echeverría, Fernando; Kieft, Jeffrey S; Sargueil, Bruno; López-Lastra, Marcelo
Activity of the human immunodeficiency virus type 1 cell cycle-dependent internal ribosomal entry site is modulated by IRES trans-acting factors Journal Article
In: Nucleic Acids Res, vol. 39, no. 14, pp. 6186–6200, 2011, ISSN: 1362-4962.
@article{pmid21482538,
title = {Activity of the human immunodeficiency virus type 1 cell cycle-dependent internal ribosomal entry site is modulated by IRES trans-acting factors},
author = {Maricarmen Vallejos and Jules Deforges and Terra-Dawn M Plank and Alejandro Letelier and Pablo Ramdohr and Christopher G Abraham and Fernando Valiente-Echeverría and Jeffrey S Kieft and Bruno Sargueil and Marcelo López-Lastra},
doi = {10.1093/nar/gkr189},
issn = {1362-4962},
year = {2011},
date = {2011-08-01},
journal = {Nucleic Acids Res},
volume = {39},
number = {14},
pages = {6186--6200},
abstract = {The 5' leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA harbors an internal ribosome entry site (IRES) that is functional during the G2/M phase of the cell cycle. Here we show that translation initiation mediated by the HIV-1 IRES requires the participation of trans-acting cellular factors other than the canonical translational machinery. We used 'standard' chemical and enzymatic probes and an 'RNA SHAPE' analysis to model the structure of the HIV-1 5' leader and we show, by means of a footprinting assay, that G2/M extracts provide protections to regions previously identified as crucial for HIV-1 IRES activity. We also assessed the impact of mutations on IRES function. Strikingly, mutations did not significantly affect IRES activity suggesting that the requirement for pre-formed stable secondary or tertiary structure within the HIV-1 IRES may not be as strict as has been described for other viral IRESes. Finally, we used a proteomic approach to identify cellular proteins within the G2/M extracts that interact with the HIV-1 5' leader. Together, data show that HIV-1 IRES-mediated translation initiation is modulated by cellular proteins.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The 5' leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA harbors an internal ribosome entry site (IRES) that is functional during the G2/M phase of the cell cycle. Here we show that translation initiation mediated by the HIV-1 IRES requires the participation of trans-acting cellular factors other than the canonical translational machinery. We used 'standard' chemical and enzymatic probes and an 'RNA SHAPE' analysis to model the structure of the HIV-1 5' leader and we show, by means of a footprinting assay, that G2/M extracts provide protections to regions previously identified as crucial for HIV-1 IRES activity. We also assessed the impact of mutations on IRES function. Strikingly, mutations did not significantly affect IRES activity suggesting that the requirement for pre-formed stable secondary or tertiary structure within the HIV-1 IRES may not be as strict as has been described for other viral IRESes. Finally, we used a proteomic approach to identify cellular proteins within the G2/M extracts that interact with the HIV-1 5' leader. Together, data show that HIV-1 IRES-mediated translation initiation is modulated by cellular proteins.2010
López-Lastra, Marcelo; Ramdohr, Pablo; Letelier, Alejandro; Vallejos, Maricarmen; Vera-Otarola, Jorge; Valiente-Echeverría, Fernando
Translation initiation of viral mRNAs Journal Article
In: Rev Med Virol, vol. 20, no. 3, pp. 177–195, 2010, ISSN: 1099-1654.
@article{pmid20440748,
title = {Translation initiation of viral mRNAs},
author = {Marcelo López-Lastra and Pablo Ramdohr and Alejandro Letelier and Maricarmen Vallejos and Jorge Vera-Otarola and Fernando Valiente-Echeverría},
doi = {10.1002/rmv.649},
issn = {1099-1654},
year = {2010},
date = {2010-05-01},
journal = {Rev Med Virol},
volume = {20},
number = {3},
pages = {177--195},
abstract = {Viruses depend on cells for their replication but have evolved mechanisms to achieve this in an efficient and, in some instances, a cell-type-specific manner. The expression of viral proteins is frequently subject to translational control. The dominant target of such control is the initiation step of protein synthesis. Indeed, during the early stages of infection, viral mRNAs must compete with their host counterparts for the protein synthetic machinery, especially for the limited pool of eukaryotic translation initiation factors (eIFs) that mediate the recruitment of ribosomes to both viral and cellular mRNAs. To circumvent this competition viruses use diverse strategies so that ribosomes can be recruited selectively to viral mRNAs. In this review we focus on the initiation of protein synthesis and outline some of the strategies used by viruses to ensure efficient translation initiation of their mRNAs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Viruses depend on cells for their replication but have evolved mechanisms to achieve this in an efficient and, in some instances, a cell-type-specific manner. The expression of viral proteins is frequently subject to translational control. The dominant target of such control is the initiation step of protein synthesis. Indeed, during the early stages of infection, viral mRNAs must compete with their host counterparts for the protein synthetic machinery, especially for the limited pool of eukaryotic translation initiation factors (eIFs) that mediate the recruitment of ribosomes to both viral and cellular mRNAs. To circumvent this competition viruses use diverse strategies so that ribosomes can be recruited selectively to viral mRNAs. In this review we focus on the initiation of protein synthesis and outline some of the strategies used by viruses to ensure efficient translation initiation of their mRNAs. Vallejos, Maricarmen; Ramdohr, Pablo; Valiente-Echeverría, Fernando; Tapia, Karla; Rodriguez, Felipe E; Lowy, Fernando; Huidobro-Toro, J Pablo; Dangerfield, John A; López-Lastra, Marcelo
The 5'-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation Journal Article
In: Nucleic Acids Res, vol. 38, no. 2, pp. 618–632, 2010, ISSN: 1362-4962.
@article{pmid19889724,
title = {The 5'-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation},
author = {Maricarmen Vallejos and Pablo Ramdohr and Fernando Valiente-Echeverría and Karla Tapia and Felipe E Rodriguez and Fernando Lowy and J Pablo Huidobro-Toro and John A Dangerfield and Marcelo López-Lastra},
doi = {10.1093/nar/gkp890},
issn = {1362-4962},
year = {2010},
date = {2010-01-01},
journal = {Nucleic Acids Res},
volume = {38},
number = {2},
pages = {618--632},
abstract = {In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.2009
Rivas-Aravena, Andrea; Ramdohr, Pablo; Vallejos, Maricarmen; Valiente-Echeverría, Fernando; Dormoy-Raclet, Virginie; Rodríguez, Felipe; Pino, Karla; Holzmann, Cristian; Huidobro-Toro, J Pablo; Gallouzi, Imed-Eddine; López-Lastra, Marcelo
The Elav-like protein HuR exerts translational control of viral internal ribosome entry sites Journal Article
In: Virology, vol. 392, no. 2, pp. 178–185, 2009, ISSN: 1096-0341.
@article{pmid19647848,
title = {The Elav-like protein HuR exerts translational control of viral internal ribosome entry sites},
author = {Andrea Rivas-Aravena and Pablo Ramdohr and Maricarmen Vallejos and Fernando Valiente-Echeverría and Virginie Dormoy-Raclet and Felipe Rodríguez and Karla Pino and Cristian Holzmann and J Pablo Huidobro-Toro and Imed-Eddine Gallouzi and Marcelo López-Lastra},
doi = {10.1016/j.virol.2009.06.050},
issn = {1096-0341},
year = {2009},
date = {2009-09-01},
journal = {Virology},
volume = {392},
number = {2},
pages = {178--185},
abstract = {The human embryonic-lethal abnormal vision (ELAV)-like protein, HuR, has been recently found to be involved in the regulation of protein synthesis. In this study we show that HuR participates in the translational control of the HIV-1 and HCV IRES elements. HuR functions as a repressor of HIV-1 IRES activity and acts as an activator of the HCV IRES. The effect of HuR was evaluated in three independent experimental systems, rabbit reticulocyte lysate, HeLa cells, and Xenopus laevis oocytes, using both overexpression and knockdown approaches. Furthermore, results suggest that HuR mediated regulation of HIV-1 and HCV IRESes does not require direct binding of the protein to the RNA nor does it need the nuclear translocation of the IRES-containing RNAs. Finally, we show that HuR has a negative impact on post-integration steps of the HIV-1 replication cycle. Thus, our observations yield novel insights into the role of HuR in the post-transcriptional regulation of HCV and HIV-1 gene expression.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The human embryonic-lethal abnormal vision (ELAV)-like protein, HuR, has been recently found to be involved in the regulation of protein synthesis. In this study we show that HuR participates in the translational control of the HIV-1 and HCV IRES elements. HuR functions as a repressor of HIV-1 IRES activity and acts as an activator of the HCV IRES. The effect of HuR was evaluated in three independent experimental systems, rabbit reticulocyte lysate, HeLa cells, and Xenopus laevis oocytes, using both overexpression and knockdown approaches. Furthermore, results suggest that HuR mediated regulation of HIV-1 and HCV IRESes does not require direct binding of the protein to the RNA nor does it need the nuclear translocation of the IRES-containing RNAs. Finally, we show that HuR has a negative impact on post-integration steps of the HIV-1 replication cycle. Thus, our observations yield novel insights into the role of HuR in the post-transcriptional regulation of HCV and HIV-1 gene expression.2007
Abarca, Katia; López, Javier; Perret, Cecilia; Guerrero, Javier; Godoy, Paula; Veloz, Ana; Valiente-Echeverría, Fernando; León, Ursula; Gutjahr, Constanza; Azócar, Teresa
Anaplasma platys in dogs, Chile Journal Article
In: Emerg Infect Dis, vol. 13, no. 9, pp. 1392–1395, 2007, ISSN: 1080-6040.
@article{pmid18252119,
title = {Anaplasma platys in dogs, Chile},
author = {Katia Abarca and Javier López and Cecilia Perret and Javier Guerrero and Paula Godoy and Ana Veloz and Fernando Valiente-Echeverría and Ursula León and Constanza Gutjahr and Teresa Azócar},
doi = {10.3201/eid1309.070021},
issn = {1080-6040},
year = {2007},
date = {2007-09-01},
journal = {Emerg Infect Dis},
volume = {13},
number = {9},
pages = {1392--1395},
abstract = {We conducted a 16S rRNA nested PCR for the genus Ehrlichia and Ehrlichia spp. with blood samples from 30 ill dogs in Chile. Phylogenetic analysis was performed by using groESL gene amplification. We identified Anaplasma platys as 1 of the etiologic agents of canine ehrlichiosis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We conducted a 16S rRNA nested PCR for the genus Ehrlichia and Ehrlichia spp. with blood samples from 30 ill dogs in Chile. Phylogenetic analysis was performed by using groESL gene amplification. We identified Anaplasma platys as 1 of the etiologic agents of canine ehrlichiosis.
2013
Monette, Anne; Valiente-Echeverría, Fernando; Rivero, Matias; Cohen, Éric A; Lopez-Lastra, Marcelo; Mouland, Andrew J
Dual mechanisms of translation initiation of the full-length HIV-1 mRNA contribute to gag synthesis Journal Article
In: PLoS One, vol. 8, no. 7, pp. e68108, 2013, ISSN: 1932-6203.
@article{pmid23861855,
title = {Dual mechanisms of translation initiation of the full-length HIV-1 mRNA contribute to gag synthesis},
author = {Anne Monette and Fernando Valiente-Echeverría and Matias Rivero and Éric A Cohen and Marcelo Lopez-Lastra and Andrew J Mouland},
doi = {10.1371/journal.pone.0068108},
issn = {1932-6203},
year = {2013},
date = {2013-01-01},
journal = {PLoS One},
volume = {8},
number = {7},
pages = {e68108},
abstract = {The precursor group-specific antigen (pr55(Gag)) is central to HIV-1 assembly. Its expression alone is sufficient to assemble into virus-like particles. It also selects the genomic RNA for encapsidation and is involved in several important virus-host interactions for viral assembly and restriction, making its synthesis essential for aspects of viral replication. Here, we show that the initiation of translation of the HIV-1 genomic RNA is mediated through both a cap-dependent and an internal ribosome entry site (IRES)-mediated mechanisms. In support of this notion, pr55(Gag) synthesis was maintained at 70% when cap-dependent translation initiation was blocked by the expression of eIF4G- and PABP targeting viral proteases in two in vitro systems and in HIV-1-expressing cells directly infected with poliovirus. While our data reveal that IRES-dependent translation of the viral genomic RNA ensures pr55(Gag) expression, the synthesis of other HIV-1 proteins, including that of pr160(Gag/Pol), Vpr and Tat is suppressed early during progressive poliovirus infection. The data presented herein implies that the unspliced HIV-1 genomic RNA utilizes both cap-dependent and IRES-dependent translation initiation to supply pr55(Gag) for virus assembly and production.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The precursor group-specific antigen (pr55(Gag)) is central to HIV-1 assembly. Its expression alone is sufficient to assemble into virus-like particles. It also selects the genomic RNA for encapsidation and is involved in several important virus-host interactions for viral assembly and restriction, making its synthesis essential for aspects of viral replication. Here, we show that the initiation of translation of the HIV-1 genomic RNA is mediated through both a cap-dependent and an internal ribosome entry site (IRES)-mediated mechanisms. In support of this notion, pr55(Gag) synthesis was maintained at 70% when cap-dependent translation initiation was blocked by the expression of eIF4G- and PABP targeting viral proteases in two in vitro systems and in HIV-1-expressing cells directly infected with poliovirus. While our data reveal that IRES-dependent translation of the viral genomic RNA ensures pr55(Gag) expression, the synthesis of other HIV-1 proteins, including that of pr160(Gag/Pol), Vpr and Tat is suppressed early during progressive poliovirus infection. The data presented herein implies that the unspliced HIV-1 genomic RNA utilizes both cap-dependent and IRES-dependent translation initiation to supply pr55(Gag) for virus assembly and production.
Valiente-Echeverría, Fernando; Vallejos, Maricarmen; Monette, Anne; Pino, Karla; Letelier, Alejandro; Huidobro-Toro, J Pablo; Mouland, Andrew J; López-Lastra, Marcelo
A cis-acting element present within the Gag open reading frame negatively impacts on the activity of the HIV-1 IRES Journal Article
In: PLoS One, vol. 8, no. 2, pp. e56962, 2013, ISSN: 1932-6203.
@article{pmid23451120,
title = {A cis-acting element present within the Gag open reading frame negatively impacts on the activity of the HIV-1 IRES},
author = {Fernando Valiente-Echeverría and Maricarmen Vallejos and Anne Monette and Karla Pino and Alejandro Letelier and J Pablo Huidobro-Toro and Andrew J Mouland and Marcelo López-Lastra},
doi = {10.1371/journal.pone.0056962},
issn = {1932-6203},
year = {2013},
date = {2013-01-01},
journal = {PLoS One},
volume = {8},
number = {2},
pages = {e56962},
abstract = {Translation initiation from the human immunodeficiency virus type-1 (HIV-1) mRNA can occur through a cap or an IRES dependent mechanism. Cap-dependent translation initiation of the HIV-1 mRNA can be inhibited by the instability element (INS)-1, a cis-acting regulatory element present within the gag open reading frame (ORF). In this study we evaluated the impact of the INS-1 on HIV-1 IRES-mediated translation initiation. Using heterologous bicistronic mRNAs, we show that the INS-1 negatively impact on HIV-1 IRES-driven translation in in vitro and in cell-based experiments. Additionally, our results show that the inhibitory effect of the INS-1 is not general to all IRESes since it does not hinder translation driven by the HCV IRES. The inhibition by the INS-1 was partially rescued in cells by the overexpression of the viral Rev protein or hnRNPA1.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Translation initiation from the human immunodeficiency virus type-1 (HIV-1) mRNA can occur through a cap or an IRES dependent mechanism. Cap-dependent translation initiation of the HIV-1 mRNA can be inhibited by the instability element (INS)-1, a cis-acting regulatory element present within the gag open reading frame (ORF). In this study we evaluated the impact of the INS-1 on HIV-1 IRES-mediated translation initiation. Using heterologous bicistronic mRNAs, we show that the INS-1 negatively impact on HIV-1 IRES-driven translation in in vitro and in cell-based experiments. Additionally, our results show that the inhibitory effect of the INS-1 is not general to all IRESes since it does not hinder translation driven by the HCV IRES. The inhibition by the INS-1 was partially rescued in cells by the overexpression of the viral Rev protein or hnRNPA1.
2012
Valiente-Echeverría, Fernando; Melnychuk, Luca; Mouland, Andrew J
Viral modulation of stress granules Journal Article
In: Virus Res, vol. 169, no. 2, pp. 430–437, 2012, ISSN: 1872-7492.
@article{pmid22705970,
title = {Viral modulation of stress granules},
author = {Fernando Valiente-Echeverría and Luca Melnychuk and Andrew J Mouland},
doi = {10.1016/j.virusres.2012.06.004},
issn = {1872-7492},
year = {2012},
date = {2012-11-01},
journal = {Virus Res},
volume = {169},
number = {2},
pages = {430--437},
abstract = {Following viral infection, the host responds by mounting a robust anti-viral response with the aim of creating an unfavorable environment for viral replication. As a countermeasure, viruses have elaborated mechanisms to subvert the host response in order to maintain viral protein synthesis and production. In the last decade, several reports have shown that viruses modulate the assembly of stress granules (SGs), which are translationally silent ribonucleoproteins (RNPs) and sites of RNA triage. This review discusses recent advances in our understanding of the interactions between viruses and the host response and how virus-induced modulations in SG abundance play fundamental roles in dictating the success of viral replication.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Following viral infection, the host responds by mounting a robust anti-viral response with the aim of creating an unfavorable environment for viral replication. As a countermeasure, viruses have elaborated mechanisms to subvert the host response in order to maintain viral protein synthesis and production. In the last decade, several reports have shown that viruses modulate the assembly of stress granules (SGs), which are translationally silent ribonucleoproteins (RNPs) and sites of RNA triage. This review discusses recent advances in our understanding of the interactions between viruses and the host response and how virus-induced modulations in SG abundance play fundamental roles in dictating the success of viral replication.
López, Javier; Abarca, Katia; Mundaca, M Isabel; Caballero, Carla; Valiente-Echeverría, Fernando
[Molecular identification of Ehrlichia canis in a dog from Arica, Chile] Journal Article
In: Rev Chilena Infectol, vol. 29, no. 5, pp. 527–530, 2012, ISSN: 0716-1018.
@article{pmid23282495,
title = {[Molecular identification of Ehrlichia canis in a dog from Arica, Chile]},
author = {Javier López and Katia Abarca and M Isabel Mundaca and Carla Caballero and Fernando Valiente-Echeverría},
doi = {10.4067/S0716-10182012000600008},
issn = {0716-1018},
year = {2012},
date = {2012-10-01},
journal = {Rev Chilena Infectol},
volume = {29},
number = {5},
pages = {527--530},
abstract = {We report a molecular confirmed case of canine ehrlichiosis caused by Ehrlichia canis. A 10-year old female crossbred Siberian from the city of Arica, which was infested by ticks, presented hemorrhagic manifestations (hematomas and snout bleeding) and prostration. Blood cell count revealed thrombocytopenia (30,000 platelets/ mm³). Immunochromatographic rapid testing for E. canis IgG was positive. Amplification and sequencing of a fragment of the 16S rRNA gen from a blood sample showed 100% homology with E. canis from Perú. This is the first report of E. canis in Chile, an agent with known zoonotic potential.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report a molecular confirmed case of canine ehrlichiosis caused by Ehrlichia canis. A 10-year old female crossbred Siberian from the city of Arica, which was infested by ticks, presented hemorrhagic manifestations (hematomas and snout bleeding) and prostration. Blood cell count revealed thrombocytopenia (30,000 platelets/ mm³). Immunochromatographic rapid testing for E. canis IgG was positive. Amplification and sequencing of a fragment of the 16S rRNA gen from a blood sample showed 100% homology with E. canis from Perú. This is the first report of E. canis in Chile, an agent with known zoonotic potential.
López, Javier; Valiente-Echeverría, Fernando; Carrasco, Marcela; Mercado, Rubén; Abarca, Katia
[Morphological and molecular identification of canine filariae in a semi-rural district of the Metropolitan Region in Chile] Journal Article
In: Rev Chilena Infectol, vol. 29, no. 3, pp. 248–289, 2012, ISSN: 0717-6341.
@article{pmid23096462,
title = {[Morphological and molecular identification of canine filariae in a semi-rural district of the Metropolitan Region in Chile]},
author = {Javier López and Fernando Valiente-Echeverría and Marcela Carrasco and Rubén Mercado and Katia Abarca},
doi = {10.4067/S0716-10182012000300006},
issn = {0717-6341},
year = {2012},
date = {2012-06-01},
journal = {Rev Chilena Infectol},
volume = {29},
number = {3},
pages = {248--289},
abstract = {INTRODUCTION: To date, there has been no definitive confirmation of the presence of zoonotic dirofilariasis in dogs in Chile.
OBJECTIVES: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations.
METHODS: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified.
CONCLUSIONS: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
INTRODUCTION: To date, there has been no definitive confirmation of the presence of zoonotic dirofilariasis in dogs in Chile.
OBJECTIVES: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations.
METHODS: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified.
CONCLUSIONS: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.
OBJECTIVES: To study the presence of dirofilarias in blood samples from dogs collected in a semi-rural district near Santiago and to compare their frequency in dogs with and without dermatological manifestations.
METHODS: We examined 100 blood samples for dog filariae infections using microscopic methods (modified Knott technique). 50 dogs presented dermatological symptoms or signs compatible with filarial infections and 50 were asymptomatic. ITS-2 and 12s rDNA gene amplification by PCR and sequencing were performed in samples microscopically positive for microfilariae. Results. We observed microfilariae in 22 dogs (22%). Of these, 16/50 (32%) were symptomatic and 6/50 (12%) were asymptomatic (p = 0.02). Morphologically, the majority of micro-filariae were similar to Dirofilaria repens, although many had a bigger size than previously described. Nucleotide sequencing of the amplified genes showed no more than 95% homology with the D. repens sequences available for comparison. D. reconditum and D. dracunculoides infections were also identified.
CONCLUSIONS: These features might indicate the presence of new species of Dirofilaria or a D. repens close related variant in Chile.
2011
C, Juan C Flores; A, Cecilia Vizcaya; B, Rafael Araos; P, Luisa Montecinos; M, Paula Godoy; Valiente-Echeverría, Fernando; P, Cecilia Perret; C, Patricia Valenzuela; B, Tamara Hirsch; G, Marcela Ferrés
[Human bocavirus in Chile: clinical characteristics and epidemiological profile in children with acute respiratory tract infections] Journal Article
In: Rev Chilena Infectol, vol. 28, no. 6, pp. 504–511, 2011, ISSN: 0716-1018.
@article{pmid22286672,
title = {[Human bocavirus in Chile: clinical characteristics and epidemiological profile in children with acute respiratory tract infections]},
author = {Juan C Flores C and Cecilia Vizcaya A and Rafael Araos B and Luisa Montecinos P and Paula Godoy M and Fernando Valiente-Echeverría and Cecilia Perret P and Patricia Valenzuela C and Tamara Hirsch B and Marcela Ferrés G},
issn = {0716-1018},
year = {2011},
date = {2011-12-01},
journal = {Rev Chilena Infectol},
volume = {28},
number = {6},
pages = {504--511},
abstract = {BACKGROUND: Human bocavirus (HBoV) is a newly discovered parvovirus found in children with acute respiratory tract infections (ARTI).
OBJECTIVES: To describe the epidemiological and clinical profile of children < 5 years old consulting for ARTI, comparing cases of HBoV monoinfection and coinfection with other known respiratory viruses. Furthermore, we aimed to estimate the prevalence of viral shedding in asymptomatic children and perform phylogenetic analysis.
PATIENTS AND METHODS: We investigated the presence of HBoV in nasopharyngeal secretions from children consulting for AlRTI and among asymptomatic controls, between 2007 and 2008, by polymerase chain reaction.
RESULTS: HBoV was detected in 79 (21.8%) of 362 nasopharyngeal swabs obtained from children with ARTI. In 60/79 (76%), coinfection with other respiratory viruses was confirmed. Most common symptoms were cough, fever and rhinorrhea. Children infected only with HBoV showed significantly lower frequencies of respiratory distress, oxygen requirements and hospital admission than those with coinfection. HBoV was detected in 6/16 (37.5%) samples from asymptomatic children. The phylogenetic analysis of viruses from Chilean patients revealed that circulating HBoV was closely related to original strains.
CONCLUSIONS: HBoV was found either in symptomatic and asymptomatic children. The severity of the disease was greater when HBoV was associated to other respiratory viruses.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Human bocavirus (HBoV) is a newly discovered parvovirus found in children with acute respiratory tract infections (ARTI).
OBJECTIVES: To describe the epidemiological and clinical profile of children < 5 years old consulting for ARTI, comparing cases of HBoV monoinfection and coinfection with other known respiratory viruses. Furthermore, we aimed to estimate the prevalence of viral shedding in asymptomatic children and perform phylogenetic analysis.
PATIENTS AND METHODS: We investigated the presence of HBoV in nasopharyngeal secretions from children consulting for AlRTI and among asymptomatic controls, between 2007 and 2008, by polymerase chain reaction.
RESULTS: HBoV was detected in 79 (21.8%) of 362 nasopharyngeal swabs obtained from children with ARTI. In 60/79 (76%), coinfection with other respiratory viruses was confirmed. Most common symptoms were cough, fever and rhinorrhea. Children infected only with HBoV showed significantly lower frequencies of respiratory distress, oxygen requirements and hospital admission than those with coinfection. HBoV was detected in 6/16 (37.5%) samples from asymptomatic children. The phylogenetic analysis of viruses from Chilean patients revealed that circulating HBoV was closely related to original strains.
CONCLUSIONS: HBoV was found either in symptomatic and asymptomatic children. The severity of the disease was greater when HBoV was associated to other respiratory viruses.
OBJECTIVES: To describe the epidemiological and clinical profile of children < 5 years old consulting for ARTI, comparing cases of HBoV monoinfection and coinfection with other known respiratory viruses. Furthermore, we aimed to estimate the prevalence of viral shedding in asymptomatic children and perform phylogenetic analysis.
PATIENTS AND METHODS: We investigated the presence of HBoV in nasopharyngeal secretions from children consulting for AlRTI and among asymptomatic controls, between 2007 and 2008, by polymerase chain reaction.
RESULTS: HBoV was detected in 79 (21.8%) of 362 nasopharyngeal swabs obtained from children with ARTI. In 60/79 (76%), coinfection with other respiratory viruses was confirmed. Most common symptoms were cough, fever and rhinorrhea. Children infected only with HBoV showed significantly lower frequencies of respiratory distress, oxygen requirements and hospital admission than those with coinfection. HBoV was detected in 6/16 (37.5%) samples from asymptomatic children. The phylogenetic analysis of viruses from Chilean patients revealed that circulating HBoV was closely related to original strains.
CONCLUSIONS: HBoV was found either in symptomatic and asymptomatic children. The severity of the disease was greater when HBoV was associated to other respiratory viruses.
Vallejos, Maricarmen; Deforges, Jules; Plank, Terra-Dawn M; Letelier, Alejandro; Ramdohr, Pablo; Abraham, Christopher G; Valiente-Echeverría, Fernando; Kieft, Jeffrey S; Sargueil, Bruno; López-Lastra, Marcelo
Activity of the human immunodeficiency virus type 1 cell cycle-dependent internal ribosomal entry site is modulated by IRES trans-acting factors Journal Article
In: Nucleic Acids Res, vol. 39, no. 14, pp. 6186–6200, 2011, ISSN: 1362-4962.
@article{pmid21482538,
title = {Activity of the human immunodeficiency virus type 1 cell cycle-dependent internal ribosomal entry site is modulated by IRES trans-acting factors},
author = {Maricarmen Vallejos and Jules Deforges and Terra-Dawn M Plank and Alejandro Letelier and Pablo Ramdohr and Christopher G Abraham and Fernando Valiente-Echeverría and Jeffrey S Kieft and Bruno Sargueil and Marcelo López-Lastra},
doi = {10.1093/nar/gkr189},
issn = {1362-4962},
year = {2011},
date = {2011-08-01},
journal = {Nucleic Acids Res},
volume = {39},
number = {14},
pages = {6186--6200},
abstract = {The 5' leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA harbors an internal ribosome entry site (IRES) that is functional during the G2/M phase of the cell cycle. Here we show that translation initiation mediated by the HIV-1 IRES requires the participation of trans-acting cellular factors other than the canonical translational machinery. We used 'standard' chemical and enzymatic probes and an 'RNA SHAPE' analysis to model the structure of the HIV-1 5' leader and we show, by means of a footprinting assay, that G2/M extracts provide protections to regions previously identified as crucial for HIV-1 IRES activity. We also assessed the impact of mutations on IRES function. Strikingly, mutations did not significantly affect IRES activity suggesting that the requirement for pre-formed stable secondary or tertiary structure within the HIV-1 IRES may not be as strict as has been described for other viral IRESes. Finally, we used a proteomic approach to identify cellular proteins within the G2/M extracts that interact with the HIV-1 5' leader. Together, data show that HIV-1 IRES-mediated translation initiation is modulated by cellular proteins.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The 5' leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA harbors an internal ribosome entry site (IRES) that is functional during the G2/M phase of the cell cycle. Here we show that translation initiation mediated by the HIV-1 IRES requires the participation of trans-acting cellular factors other than the canonical translational machinery. We used 'standard' chemical and enzymatic probes and an 'RNA SHAPE' analysis to model the structure of the HIV-1 5' leader and we show, by means of a footprinting assay, that G2/M extracts provide protections to regions previously identified as crucial for HIV-1 IRES activity. We also assessed the impact of mutations on IRES function. Strikingly, mutations did not significantly affect IRES activity suggesting that the requirement for pre-formed stable secondary or tertiary structure within the HIV-1 IRES may not be as strict as has been described for other viral IRESes. Finally, we used a proteomic approach to identify cellular proteins within the G2/M extracts that interact with the HIV-1 5' leader. Together, data show that HIV-1 IRES-mediated translation initiation is modulated by cellular proteins.
2010
López-Lastra, Marcelo; Ramdohr, Pablo; Letelier, Alejandro; Vallejos, Maricarmen; Vera-Otarola, Jorge; Valiente-Echeverría, Fernando
Translation initiation of viral mRNAs Journal Article
In: Rev Med Virol, vol. 20, no. 3, pp. 177–195, 2010, ISSN: 1099-1654.
@article{pmid20440748,
title = {Translation initiation of viral mRNAs},
author = {Marcelo López-Lastra and Pablo Ramdohr and Alejandro Letelier and Maricarmen Vallejos and Jorge Vera-Otarola and Fernando Valiente-Echeverría},
doi = {10.1002/rmv.649},
issn = {1099-1654},
year = {2010},
date = {2010-05-01},
journal = {Rev Med Virol},
volume = {20},
number = {3},
pages = {177--195},
abstract = {Viruses depend on cells for their replication but have evolved mechanisms to achieve this in an efficient and, in some instances, a cell-type-specific manner. The expression of viral proteins is frequently subject to translational control. The dominant target of such control is the initiation step of protein synthesis. Indeed, during the early stages of infection, viral mRNAs must compete with their host counterparts for the protein synthetic machinery, especially for the limited pool of eukaryotic translation initiation factors (eIFs) that mediate the recruitment of ribosomes to both viral and cellular mRNAs. To circumvent this competition viruses use diverse strategies so that ribosomes can be recruited selectively to viral mRNAs. In this review we focus on the initiation of protein synthesis and outline some of the strategies used by viruses to ensure efficient translation initiation of their mRNAs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Viruses depend on cells for their replication but have evolved mechanisms to achieve this in an efficient and, in some instances, a cell-type-specific manner. The expression of viral proteins is frequently subject to translational control. The dominant target of such control is the initiation step of protein synthesis. Indeed, during the early stages of infection, viral mRNAs must compete with their host counterparts for the protein synthetic machinery, especially for the limited pool of eukaryotic translation initiation factors (eIFs) that mediate the recruitment of ribosomes to both viral and cellular mRNAs. To circumvent this competition viruses use diverse strategies so that ribosomes can be recruited selectively to viral mRNAs. In this review we focus on the initiation of protein synthesis and outline some of the strategies used by viruses to ensure efficient translation initiation of their mRNAs.
Vallejos, Maricarmen; Ramdohr, Pablo; Valiente-Echeverría, Fernando; Tapia, Karla; Rodriguez, Felipe E; Lowy, Fernando; Huidobro-Toro, J Pablo; Dangerfield, John A; López-Lastra, Marcelo
The 5'-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation Journal Article
In: Nucleic Acids Res, vol. 38, no. 2, pp. 618–632, 2010, ISSN: 1362-4962.
@article{pmid19889724,
title = {The 5'-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation},
author = {Maricarmen Vallejos and Pablo Ramdohr and Fernando Valiente-Echeverría and Karla Tapia and Felipe E Rodriguez and Fernando Lowy and J Pablo Huidobro-Toro and John A Dangerfield and Marcelo López-Lastra},
doi = {10.1093/nar/gkp890},
issn = {1362-4962},
year = {2010},
date = {2010-01-01},
journal = {Nucleic Acids Res},
volume = {38},
number = {2},
pages = {618--632},
abstract = {In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.
2009
Rivas-Aravena, Andrea; Ramdohr, Pablo; Vallejos, Maricarmen; Valiente-Echeverría, Fernando; Dormoy-Raclet, Virginie; Rodríguez, Felipe; Pino, Karla; Holzmann, Cristian; Huidobro-Toro, J Pablo; Gallouzi, Imed-Eddine; López-Lastra, Marcelo
The Elav-like protein HuR exerts translational control of viral internal ribosome entry sites Journal Article
In: Virology, vol. 392, no. 2, pp. 178–185, 2009, ISSN: 1096-0341.
@article{pmid19647848,
title = {The Elav-like protein HuR exerts translational control of viral internal ribosome entry sites},
author = {Andrea Rivas-Aravena and Pablo Ramdohr and Maricarmen Vallejos and Fernando Valiente-Echeverría and Virginie Dormoy-Raclet and Felipe Rodríguez and Karla Pino and Cristian Holzmann and J Pablo Huidobro-Toro and Imed-Eddine Gallouzi and Marcelo López-Lastra},
doi = {10.1016/j.virol.2009.06.050},
issn = {1096-0341},
year = {2009},
date = {2009-09-01},
journal = {Virology},
volume = {392},
number = {2},
pages = {178--185},
abstract = {The human embryonic-lethal abnormal vision (ELAV)-like protein, HuR, has been recently found to be involved in the regulation of protein synthesis. In this study we show that HuR participates in the translational control of the HIV-1 and HCV IRES elements. HuR functions as a repressor of HIV-1 IRES activity and acts as an activator of the HCV IRES. The effect of HuR was evaluated in three independent experimental systems, rabbit reticulocyte lysate, HeLa cells, and Xenopus laevis oocytes, using both overexpression and knockdown approaches. Furthermore, results suggest that HuR mediated regulation of HIV-1 and HCV IRESes does not require direct binding of the protein to the RNA nor does it need the nuclear translocation of the IRES-containing RNAs. Finally, we show that HuR has a negative impact on post-integration steps of the HIV-1 replication cycle. Thus, our observations yield novel insights into the role of HuR in the post-transcriptional regulation of HCV and HIV-1 gene expression.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The human embryonic-lethal abnormal vision (ELAV)-like protein, HuR, has been recently found to be involved in the regulation of protein synthesis. In this study we show that HuR participates in the translational control of the HIV-1 and HCV IRES elements. HuR functions as a repressor of HIV-1 IRES activity and acts as an activator of the HCV IRES. The effect of HuR was evaluated in three independent experimental systems, rabbit reticulocyte lysate, HeLa cells, and Xenopus laevis oocytes, using both overexpression and knockdown approaches. Furthermore, results suggest that HuR mediated regulation of HIV-1 and HCV IRESes does not require direct binding of the protein to the RNA nor does it need the nuclear translocation of the IRES-containing RNAs. Finally, we show that HuR has a negative impact on post-integration steps of the HIV-1 replication cycle. Thus, our observations yield novel insights into the role of HuR in the post-transcriptional regulation of HCV and HIV-1 gene expression.
2007
Abarca, Katia; López, Javier; Perret, Cecilia; Guerrero, Javier; Godoy, Paula; Veloz, Ana; Valiente-Echeverría, Fernando; León, Ursula; Gutjahr, Constanza; Azócar, Teresa
Anaplasma platys in dogs, Chile Journal Article
In: Emerg Infect Dis, vol. 13, no. 9, pp. 1392–1395, 2007, ISSN: 1080-6040.
@article{pmid18252119,
title = {Anaplasma platys in dogs, Chile},
author = {Katia Abarca and Javier López and Cecilia Perret and Javier Guerrero and Paula Godoy and Ana Veloz and Fernando Valiente-Echeverría and Ursula León and Constanza Gutjahr and Teresa Azócar},
doi = {10.3201/eid1309.070021},
issn = {1080-6040},
year = {2007},
date = {2007-09-01},
journal = {Emerg Infect Dis},
volume = {13},
number = {9},
pages = {1392--1395},
abstract = {We conducted a 16S rRNA nested PCR for the genus Ehrlichia and Ehrlichia spp. with blood samples from 30 ill dogs in Chile. Phylogenetic analysis was performed by using groESL gene amplification. We identified Anaplasma platys as 1 of the etiologic agents of canine ehrlichiosis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We conducted a 16S rRNA nested PCR for the genus Ehrlichia and Ehrlichia spp. with blood samples from 30 ill dogs in Chile. Phylogenetic analysis was performed by using groESL gene amplification. We identified Anaplasma platys as 1 of the etiologic agents of canine ehrlichiosis.