The Experts below are selected from a list of 1113 Experts worldwide ranked by ideXlab platform
Susana Guix - One of the best experts on this subject based on the ideXlab platform.
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Human Astrovirus outbreak in a daycare center and propagation among household contacts
Viruses, 2021Co-Authors: Ignacio Parron, Susana Guix, Elsa Plasencia, Thais Cornejosanchez, Mireia Jane, Cristina Perez, Conchita Izquierdo, Angela DominguezAbstract:We investigated an outbreak of acute gastroenteritis due to Human Astrovirus in a daycare center, describing the transmission mechanism, the most affected age groups, conditioning factors and the extent of the outbreak among household contacts of the daycare center attenders. Data were collected from persons exposed at the daycare center and their home contacts. Fecal samples from affected and non-affected daycare center attenders were analyzed for viruses causing acute gastroenteritis by RT-PCR. The percentage of households affected and the attack rates (AR) were calculated. The attack rates were compared using the rate ratio (RR) with 95% confidence intervals. Information was obtained from 245 people (76 attenders and 169 contacts) of whom 49 were clinical cases. Five HAstV-4, two HAstV-8 and three non-typable HAstV cases were identified (six from clinical cases and four from asymptomatic infected people). The global AR was 20% (41.2% in children aged < 2 years). Data were obtained from 67 households: 20 households of affected attenders and 47 of non-affected attendees. Household contacts of affected attenders had a higher AR (74.3%) than that of non-affected attendees (2.4%). We found asymptomatic infections amongst daycare attendees. The transmission of HAstV during the outbreak was not limited to the daycare center but extended to household contacts of both affected and non-affected attenders.
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epidemiology of classic and novel Human Astrovirus gastroenteritis and beyond
Viruses, 2017Co-Authors: Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Since they were identified in 1975, Human Astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent Astroviruses infecting Humans have been recently discovered and associated with extra-intestinal infections. The report of cases of fatal meningitis and encephalitis, especially in immunocompromised individuals, has broadened their disease spectrum. Although zoonotic transmission among animal and Human Astroviruses has not been clearly recognized, the genetic similarity between some Human and animal viruses makes it likely to occur. This review provides an update on the epidemiology of both classic and novel Human Astroviruses, and a comprehensive view on confirmed or potential association between Astrovirus and Human disease.
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RESEARCH ARTICLE Open Access Clinical surveillance for Human Astrovirus in
2016Co-Authors: Monastir Region Tunisia, Susana Guix, Abir Monastiri, Mahjoub Aouni, Badereddine Mechri, Neji Gueddiche, Marc Lopez-roig, Nabil Ben, Salem Abid, Sabeur HamamiAbstract:Background/aims: Astroviruses (AstVs) are enteric viruses that can cause gastroenteritis in children. This study is part of monitoring the circulation of Astroviruses in children hospitalized and/or outpatients for acute gastroenteritis at the primary care center of Ouerdanine or at the Pediatric Department of the University Hospital Fattouma-Bourguiba (Monastir, Tunisia). The aims of our study were to know the prevalence of Human Astrovirus in clinical samples of children, characterize the strains and evaluate the infectivity of isolated strains on cell culture. Methods: Fifty stool samples were collected from children under five years old in the region of Monastir (Tunisia) from October 2010 to June 2011. All specimens were subjected to RT-PCR amplification followed by sequencing and phylogenetic analysis. Results: The study shows a low prevalence of Astrovirus (4 %) in children. The two positive samples obtained were HAstV type 3. Samples that were RT-PCR positive were cultured in CaCO-2 cells and the presence of infectious viral particles was confirmed. The phylogenetic analysis shows that the different HAstV-3 strains isolated in Tunisia are grouped into two clusters. The first cluster includes strains obtained in 2004, which belong to lineage HAstV-3a, while strains isolated in 2010 belong to lineage HAstV-3c. Conclusions: This study is part of monitoring the circulation of Astroviruses in children younger than five years old from Monastir region, Tunisia. The results show low prevalence (4 %). All genotyped samples belonged to lineage HAstV-3c, which could be presently emerging. Two different lineages have been isolated in Tunisia: HAstV-3a in 2004 and HAstV-3c in 2010
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clinical surveillance for Human Astrovirus in monastir region tunisia
BMC Public Health, 2015Co-Authors: Abir Monastiri, Susana Guix, Mahjoub Aouni, Badereddine Mechri, Marc Lopezroig, Nabil Abid, Neji Gueddiche, Sabeur Hamami, Lamjed Boughzala, Jordi SerracoboAbstract:Astroviruses (AstVs) are enteric viruses that can cause gastroenteritis in children. This study is part of monitoring the circulation of Astroviruses in children hospitalized and/or outpatients for acute gastroenteritis at the primary care center of Ouerdanine or at the Pediatric Department of the University Hospital Fattouma-Bourguiba (Monastir, Tunisia). The aims of our study were to know the prevalence of Human Astrovirus in clinical samples of children, characterize the strains and evaluate the infectivity of isolated strains on cell culture. Fifty stool samples were collected from children under five years old in the region of Monastir (Tunisia) from October 2010 to June 2011. All specimens were subjected to RT-PCR amplification followed by sequencing and phylogenetic analysis. The study shows a low prevalence of Astrovirus (4 %) in children. The two positive samples obtained were HAstV type 3. Samples that were RT-PCR positive were cultured in CaCO-2 cells and the presence of infectious viral particles was confirmed. The phylogenetic analysis shows that the different HAstV-3 strains isolated in Tunisia are grouped into two clusters. The first cluster includes strains obtained in 2004, which belong to lineage HAstV-3a, while strains isolated in 2010 belong to lineage HAstV-3c. This study is part of monitoring the circulation of Astroviruses in children younger than five years old from Monastir region, Tunisia. The results show low prevalence (4 %). All genotyped samples belonged to lineage HAstV-3c, which could be presently emerging. Two different lineages have been isolated in Tunisia: HAstV-3a in 2004 and HAstV-3c in 2010.
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Type I Interferon Response Is Delayed in Human Astrovirus Infections
PloS one, 2015Co-Authors: Susana Guix, Albert Bosch, Anna Pérez-bosque, Lluïsa Miró, Miquel Moretó, Rosa M. PintóAbstract:Type I interferon (IFN) activation and its subsequent effects are important in the response to viral infections. Here we show that Human Astroviruses (HAstVs), which are important agents of acute gastroenteritis in children, induce a mild and delayed IFN response upon infecting CaCo-2 cells. Although IFN-β mRNA is detected within infected cells and supernatant from infected cells show antiviral activity against the replication of other well-known IFN-sensitive viruses, these responses occur at late stages of infection once genome replication has taken place. On the other hand, HAstV replication can be partially reduced by the addition of exogenous IFN, and inhibition of IFN activation by BX795 enhances viral replication, indicating that HAstVs are IFN-sensitive viruses. Finally, different levels of IFN response were observed in cells infected with different HAstV mutants with changes in the hypervariable region of nsP1a/4, suggesting that nsP1a/4 genotype may potentially have clinical implications due to its correlation with the viral replication phenotype and the antiviral responses induced within infected cells.
Rosa M. Pintó - One of the best experts on this subject based on the ideXlab platform.
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epidemiology of classic and novel Human Astrovirus gastroenteritis and beyond
Viruses, 2017Co-Authors: Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Since they were identified in 1975, Human Astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent Astroviruses infecting Humans have been recently discovered and associated with extra-intestinal infections. The report of cases of fatal meningitis and encephalitis, especially in immunocompromised individuals, has broadened their disease spectrum. Although zoonotic transmission among animal and Human Astroviruses has not been clearly recognized, the genetic similarity between some Human and animal viruses makes it likely to occur. This review provides an update on the epidemiology of both classic and novel Human Astroviruses, and a comprehensive view on confirmed or potential association between Astrovirus and Human disease.
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Type I Interferon Response Is Delayed in Human Astrovirus Infections
PloS one, 2015Co-Authors: Susana Guix, Albert Bosch, Anna Pérez-bosque, Lluïsa Miró, Miquel Moretó, Rosa M. PintóAbstract:Type I interferon (IFN) activation and its subsequent effects are important in the response to viral infections. Here we show that Human Astroviruses (HAstVs), which are important agents of acute gastroenteritis in children, induce a mild and delayed IFN response upon infecting CaCo-2 cells. Although IFN-β mRNA is detected within infected cells and supernatant from infected cells show antiviral activity against the replication of other well-known IFN-sensitive viruses, these responses occur at late stages of infection once genome replication has taken place. On the other hand, HAstV replication can be partially reduced by the addition of exogenous IFN, and inhibition of IFN activation by BX795 enhances viral replication, indicating that HAstVs are IFN-sensitive viruses. Finally, different levels of IFN response were observed in cells infected with different HAstV mutants with changes in the hypervariable region of nsP1a/4, suggesting that nsP1a/4 genotype may potentially have clinical implications due to its correlation with the viral replication phenotype and the antiviral responses induced within infected cells.
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Identification of Human Astrovirus Genome-Linked Protein (VPg) Essential for Virus Infectivity
Journal of virology, 2012Co-Authors: Cristina Fuentes, Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Viral genome-linked proteins (VPgs) have been identified in several single-stranded positive-sense RNA virus families. The presence of such protein in the family Astroviridae has not been fully elucidated, although a putative VPg coding region in open reading frame 1a (ORF1a) of Astrovirus with high amino acid sequence similarity to the VPg coding region of Caliciviridae has been previously identified. In this work we present several experimental findings that show that Human Astrovirus (HAstV) RNA encodes a VPg essential for viral infectivity: (i) RNase treatment of RNA purified from Astrovirus-infected cells results in a single protein of 13 to 15 kDa, compatible with the predicted Astrovirus VPg size; (ii) the antibody used to detect this 13- to 15-kDa protein is specifically directed against a region that includes the putative VPg coding region; (iii) the 13- to 15-kDa protein detected has been partially sequenced and the sequence obtained is contained in the computationally predicted VPg; (iv) the protein resulting from this putative VPg coding region is a highly disordered protein, resembling the VPg of sobemo-, calici- and potyviruses; (v) proteolytic treatment of the genomic RNA leads to loss of infectivity; and (vi) mutagenesis of Tyr-693 included in the putative VPg protein is lethal for HAstV replication, which strongly supports its functional role in the covalent link with the viral RNA.
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Identification of Human Astrovirus genome-linked protein (VPg) essential for virus infectivity
2012Co-Authors: Cristina Fuentes, Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Viral genome-linked proteins (VPgs) have been identified in several single-stranded positive-sense RNA virus families. The pres-ence of such protein in the family Astroviridae has not been fully elucidated, although a putative VPg coding region in open read-ing frame 1a (ORF1a) of Astrovirus with high amino acid sequence similarity to the VPg coding region of Caliciviridae has been previously identified. In this work we present several experimental findings that show that Human Astrovirus (HAstV) RNA en-codes a VPg essential for viral infectivity: (i) RNase treatment of RNA purified from Astrovirus-infected cells results in a single protein of 13 to 15 kDa, compatible with the predicted Astrovirus VPg size; (ii) the antibody used to detect this 13- to 15-kDa pro-tein is specifically directed against a region that includes the putative VPg coding region; (iii) the 13- to 15-kDa protein detected has been partially sequenced and the sequence obtained is contained in the computationally predicted VPg; (iv) the protein re-sulting from this putative VPg coding region is a highly disordered protein, resembling the VPg of sobemo-, calici- and potyvi-ruses; (v) proteolytic treatment of the genomic RNA leads to loss of infectivity; and (vi) mutagenesis of Tyr-693 included in the putative VPg protein is lethal for HAstV replication, which strongly supports its functional role in the covalent link with the vi-ral RNA. Viral genome-linked proteins (VPgs) are virus-encoded smallproteins that are covalently linked to the 5 = terminus of many RNA viral genomes through a phosphodiester bond. Since the discovery of such a protein in the poliovirus genome, several ani
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the c terminal nsp1a protein of Human Astrovirus is a phosphoprotein that interacts with the viral polymerase
Journal of Virology, 2011Co-Authors: Cristina Fuentes, Albert Bosch, Susana Guix, Rosa M. PintóAbstract:Human Astrovirus nonstructural C-terminal nsP1a protein (nsP1a/4) colocalizes with the endoplasmic reticulum and viral RNA. It has been suggested that nsP1a/4 protein is involved in the RNA replication process in endoplasmic reticulum-derived intracellular membranes. A hypervariable region (HVR) is contained in the nsP1a/4 protein, and different replicative patterns can be distinguished depending on its variability. In the present work, both the Astrovirus RNA-dependent RNA polymerase and four types (IV, V, VI, and XII) of nsP1a/4 proteins have been cloned and expressed in the baculovirus system to analyze their interactions. Different isoforms of each of the nsP1a/4 proteins exist: a nonphosphorylated isoform and different phosphorylated isoforms. While the polymerase accumulates as a monomer, the nsP1a/4 proteins accumulate as oligomers. The oligomerization domain of nsP1a/4-V is mapped between residues 176 and 209. For all studied genotypes, oligomers mainly contain the nonphosphorylated isoform. When RNA polymerase is coexpressed with nsP1a/4 proteins, they interact, likely forming heterodimers. The polymerase binding region has been mapped in the nsP1a/4-V protein between residues 88 and 176. Phosphorylated isoforms of nsP1a/4 type VI show a stronger interactive pattern with the polymerase than the nonphosphorylated isoform. This difference is not observed in genotypes IV and V, suggesting a role of the HVR in modulating the interaction of the nsP1a/4 protein with the polymerase through phosphorylation/dephosphorylation of some critical residues.
Carlos F Arias - One of the best experts on this subject based on the ideXlab platform.
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structures of two Human Astrovirus capsid neutralizing antibody complexes reveal distinct epitopes and inhibition of virus attachment to cells
Journal of Virology, 2021Co-Authors: Lena Ricemeyer, Carlos F Arias, Nayeli Aguilarhernandez, Tomas Lopez, Rafaela Espinosa, Sarah Lanning, Santanu Mukherjee, Carolina Cuellar, Susana Lopez, Rebecca M DuboisAbstract:Human Astrovirus is an important cause of viral gastroenteritis worldwide. Young children, the elderly, and the immunocompromised are especially at risk for contracting severe disease. However, no vaccines exist to combat Human Astrovirus infection. Evidence points to the importance of antibodies in enabling protection of healthy adults from reinfection. To develop an effective subunit vaccine that broadly protects against diverse Astrovirus serotypes, we must understand how neutralizing antibodies target the capsid surface at the molecular level. Here, we report the structures of the Human Astrovirus capsid spike domain bound to two neutralizing monoclonal antibodies. These antibodies bind two distinct conformational epitopes on the spike surface. We add to existing evidence that the Human Astrovirus capsid spike contains a receptor-binding domain and demonstrate that both antibodies neutralize Human Astrovirus by blocking virus attachment to host cells. We identify patches of conserved amino acids that overlap or border the antibody epitopes and may constitute a receptor-binding site. Our findings provide a basis to develop therapies that prevent and treat Human Astrovirus gastroenteritis. Importance Human Astroviruses infect nearly every person in the world during childhood and cause diarrhea, vomiting, and fever. Despite the prevalence of this virus, little is known about how antibodies block virus infection. Here, we determined crystal structures of the Astrovirus capsid protein in complex with two virus-neutralizing antibodies. We show that the antibodies bind two distinct sites on the capsid spike domain; however, both antibodies block virus attachment to Human cells. Importantly, our findings support the use of the Human Astrovirus capsid spike as an antigen in a subunit-based vaccine to prevent Astrovirus disease.
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the association of Human Astrovirus with extracellular vesicles facilitates cell infection and protects the virus from neutralizing antibodies
bioRxiv, 2021Co-Authors: B Carlos, Carlos F Arias, Susana Lopez, Ivan R Quevedo, Pavel IsaAbstract:Abstract Viral gastroenteritis has a global distribution and represents a high risk for vulnerable population and children under 5 years because of acute diarrhea, fever and dehydration. Human Astroviruses (HAstV) have been identified as the third most important cause of viral gastroenteritis in pediatric and immunocompromised patients. Furthermore, HAstV has been reported in biopsies taken from patients with encephalitis, meningitis and acute respiratory infection, yet it is not clear how the virus reaches these organs. In this work we tested the possibility that the released Astrovirus particles could be associated with extracellular vesicles. Comparison between vesicles purified from Astrovirus- and mock-infected cells showed that infection with HAstV Yuc8 enhances production of vesicles larger than 150 nm. These vesicles contain CD63 and Alix, two markers of vesicular structures. Some of the extracellular virus was found associated with vesicular membranes, and this association facilitates cell infection in the absence of trypsin activation and protects virions from neutralizing antibodies. Our findings suggest a new pathway for HAstV spread and might represent an explanation for the extraintestinal presence of some Astrovirus strains. Importance Astroviruses are an important cause of diarrhea in children; recently some reports have found these viruses in extra-intestinal organs, including the central nervous system, causing unexpected clinical disease. In this work we found that Human Astrovirus strain Yuc8 associates with extracellular vesicles, possibly during or after their cell egress. The association with vesicles seems to increase Astrovirus infectivity in less susceptible cells, and renders virus particles insensitive to neutralization by antibodies. These data suggest that extracellular vesicles could represent a novel pathway for Astrovirus to disseminate outside the gastrointestinal tract.
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minimal capsid composition of infectious Human Astrovirus
Virology, 2018Co-Authors: Nayeli Aguilarhernandez, Susana Lopez, Carlos F AriasAbstract:Abstract Human Astrovirus is an important etiological agent of acute gastroenteritis in young children. Despite advances in the characterization of the structure of the virion by cryo-electron microscopy and of capsid proteins by x-ray crystallography, the definition of the minimal polypeptide composition of infectious virus particles has been elusive. In this work we show that mature infectious particles are composed by only two proteins; VP34 that forms the core domain of the virus, and VP27 that constitutes the 30 dimeric spikes present on the virus surface. Our results also indicate that during the transition of immature (90 spikes) to mature (30 spikes) virus particles, that occur during trypsin activation, the viral protein VP25, that most likely forms the 60 spikes that are lost during maturation, detaches from the virus particle. This information is relevant to better understand the biology of virus entry and also for the efficient development of subunit vaccines.
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The Ubiquitin-Proteasome System Is Necessary for Efficient Replication of Human Astrovirus.
Journal of virology, 2018Co-Authors: Luis A. Casorla-pérez, Susana Lopez, Tomas Lopez, Carlos F AriasAbstract:Astroviruses, members of the family Astroviridae, represent an important cause of Human gastroenteritis in the world. The cellular factors required for Astrovirus replication have been poorly studied. In this work, we evaluated the relevance of the ubiquitin-proteasome system (UPS) in the replication of Yuc8, a Human Astrovirus serotype 8 strain. We found that proteasome inhibitors decrease the production of infectious viral progeny at a step in the replication cycle subsequent to virus entry. The inhibition of proteasome activity decreases viral RNA levels and viral protein synthesis; similarly, the inhibition of ubiquitination by chemical inhibitors or RNA interference (RNAi) reduces the production of viral progeny as well as viral protein synthesis. The effect on viral progeny production induced by proteasome inhibitors is not explained by a reduction in the pool of monoubiquitin or the induction of early apoptosis or autophagy. Our observations are consistent with the need of the proteolytic activity of the UPS for the efficient replication of the virus and suggest that UPS is necessary for the production of genomic and subgenomic RNA but not for antigenomic RNA. IMPORTANCE Astroviruses are a major cause of gastroenteritis in young Humans and animals, and recently, it was associated with fatal encephalitis in Humans. The role of the ubiquitin-proteasome system in the replication of these viruses has not been studied previously. In this work, we present evidence that supports that the proteolytic activity of the proteasome is necessary for efficient viral progeny production and that this proteolytic system is required for the accumulation of both genomic and subgenomic viral RNAs.
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Crystal Structure of the Human Astrovirus Capsid Protein
Journal of virology, 2016Co-Authors: Yukimatsu Toh, Ernesto Mendez, Carlos F Arias, Justin Harper, Kelly A. Dryden, Mark Yeager, Yizhi Jane TaoAbstract:ABSTRACT Human Astrovirus (HAstV) is a leading cause of viral diarrhea in infants and young children worldwide. HAstV is a nonenveloped virus with a T=3 capsid and a positive-sense RNA genome. The capsid protein (CP) of HAstV is synthesized as a 90-kDa precursor (VP90) that can be divided into three linear domains: a conserved N-terminal domain, a hypervariable domain, and an acidic C-terminal domain. Maturation of HAstV requires proteolytic processing of the Astrovirus CP both inside and outside the host cell, resulting in the removal of the C-terminal domain and the breakdown of the rest of the CP into three predominant protein species with molecular masses of ∼34, 27/29, and 25/26 kDa, respectively. We have now solved the crystal structure of VP90 71–415 (amino acids [aa] 71 to 415 of VP90) of Human Astrovirus serotype 8 at a 2.15-A resolution. VP90 71–415 encompasses the conserved N-terminal domain of VP90 but lacks the hypervariable domain, which forms the capsid surface spikes. The structure of VP90 71–415 is comprised of two domains: an S domain, which adopts the typical jelly-roll β-barrel fold, and a P1 domain, which forms a squashed β-barrel consisting of six antiparallel β-strands similar to what was observed in the hepatitis E virus (HEV) capsid structure. Fitting of the VP90 71–415 structure into the cryo-electron microscopy (EM) maps of HAstV produced an atomic model for a continuous, T=3 icosahedral capsid shell. Our pseudoatomic model of the Human HAstV capsid shell provides valuable insights into intermolecular interactions required for capsid assembly and trypsin-mediated proteolytic maturation needed for virus infectivity. Such information has potential applications in the development of a virus-like particle (VLP) vaccine as well as small-molecule drugs targeting Astrovirus assembly/maturation. IMPORTANCE Human Astrovirus (HAstV) is a leading cause of viral diarrhea in infants and young children worldwide. As a nonenveloped virus, HAstV exhibits an intriguing feature in that its maturation requires extensive proteolytic processing of the Astrovirus capsid protein (CP) both inside and outside the host cell. Mature HAstV contains three predominant protein species, but the mechanism for acquired infectivity upon maturation is unclear. We have solved the crystal structure of VP90 71–415 of Human Astrovirus serotype 8. VP90 71–415 encompasses the conserved N-terminal domain of the viral CP. Fitting of the VP90 71–415 structure into the cryo-EM maps of HAstV produced an atomic model for the T=3 icosahedral capsid. Our model of the HAstV capsid provides valuable insights into intermolecular interactions required for capsid assembly and trypsin-mediated proteolytic maturation. Such information has potential applications in the development of a VLP vaccine as well as small-molecule drugs targeting Astrovirus assembly/maturation.
Albert Bosch - One of the best experts on this subject based on the ideXlab platform.
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epidemiology of classic and novel Human Astrovirus gastroenteritis and beyond
Viruses, 2017Co-Authors: Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Since they were identified in 1975, Human Astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent Astroviruses infecting Humans have been recently discovered and associated with extra-intestinal infections. The report of cases of fatal meningitis and encephalitis, especially in immunocompromised individuals, has broadened their disease spectrum. Although zoonotic transmission among animal and Human Astroviruses has not been clearly recognized, the genetic similarity between some Human and animal viruses makes it likely to occur. This review provides an update on the epidemiology of both classic and novel Human Astroviruses, and a comprehensive view on confirmed or potential association between Astrovirus and Human disease.
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Type I Interferon Response Is Delayed in Human Astrovirus Infections
PloS one, 2015Co-Authors: Susana Guix, Albert Bosch, Anna Pérez-bosque, Lluïsa Miró, Miquel Moretó, Rosa M. PintóAbstract:Type I interferon (IFN) activation and its subsequent effects are important in the response to viral infections. Here we show that Human Astroviruses (HAstVs), which are important agents of acute gastroenteritis in children, induce a mild and delayed IFN response upon infecting CaCo-2 cells. Although IFN-β mRNA is detected within infected cells and supernatant from infected cells show antiviral activity against the replication of other well-known IFN-sensitive viruses, these responses occur at late stages of infection once genome replication has taken place. On the other hand, HAstV replication can be partially reduced by the addition of exogenous IFN, and inhibition of IFN activation by BX795 enhances viral replication, indicating that HAstVs are IFN-sensitive viruses. Finally, different levels of IFN response were observed in cells infected with different HAstV mutants with changes in the hypervariable region of nsP1a/4, suggesting that nsP1a/4 genotype may potentially have clinical implications due to its correlation with the viral replication phenotype and the antiviral responses induced within infected cells.
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Identification of Human Astrovirus Genome-Linked Protein (VPg) Essential for Virus Infectivity
Journal of virology, 2012Co-Authors: Cristina Fuentes, Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Viral genome-linked proteins (VPgs) have been identified in several single-stranded positive-sense RNA virus families. The presence of such protein in the family Astroviridae has not been fully elucidated, although a putative VPg coding region in open reading frame 1a (ORF1a) of Astrovirus with high amino acid sequence similarity to the VPg coding region of Caliciviridae has been previously identified. In this work we present several experimental findings that show that Human Astrovirus (HAstV) RNA encodes a VPg essential for viral infectivity: (i) RNase treatment of RNA purified from Astrovirus-infected cells results in a single protein of 13 to 15 kDa, compatible with the predicted Astrovirus VPg size; (ii) the antibody used to detect this 13- to 15-kDa protein is specifically directed against a region that includes the putative VPg coding region; (iii) the 13- to 15-kDa protein detected has been partially sequenced and the sequence obtained is contained in the computationally predicted VPg; (iv) the protein resulting from this putative VPg coding region is a highly disordered protein, resembling the VPg of sobemo-, calici- and potyviruses; (v) proteolytic treatment of the genomic RNA leads to loss of infectivity; and (vi) mutagenesis of Tyr-693 included in the putative VPg protein is lethal for HAstV replication, which strongly supports its functional role in the covalent link with the viral RNA.
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Identification of Human Astrovirus genome-linked protein (VPg) essential for virus infectivity
2012Co-Authors: Cristina Fuentes, Albert Bosch, Rosa M. Pintó, Susana GuixAbstract:Viral genome-linked proteins (VPgs) have been identified in several single-stranded positive-sense RNA virus families. The pres-ence of such protein in the family Astroviridae has not been fully elucidated, although a putative VPg coding region in open read-ing frame 1a (ORF1a) of Astrovirus with high amino acid sequence similarity to the VPg coding region of Caliciviridae has been previously identified. In this work we present several experimental findings that show that Human Astrovirus (HAstV) RNA en-codes a VPg essential for viral infectivity: (i) RNase treatment of RNA purified from Astrovirus-infected cells results in a single protein of 13 to 15 kDa, compatible with the predicted Astrovirus VPg size; (ii) the antibody used to detect this 13- to 15-kDa pro-tein is specifically directed against a region that includes the putative VPg coding region; (iii) the 13- to 15-kDa protein detected has been partially sequenced and the sequence obtained is contained in the computationally predicted VPg; (iv) the protein re-sulting from this putative VPg coding region is a highly disordered protein, resembling the VPg of sobemo-, calici- and potyvi-ruses; (v) proteolytic treatment of the genomic RNA leads to loss of infectivity; and (vi) mutagenesis of Tyr-693 included in the putative VPg protein is lethal for HAstV replication, which strongly supports its functional role in the covalent link with the vi-ral RNA. Viral genome-linked proteins (VPgs) are virus-encoded smallproteins that are covalently linked to the 5 = terminus of many RNA viral genomes through a phosphodiester bond. Since the discovery of such a protein in the poliovirus genome, several ani
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the c terminal nsp1a protein of Human Astrovirus is a phosphoprotein that interacts with the viral polymerase
Journal of Virology, 2011Co-Authors: Cristina Fuentes, Albert Bosch, Susana Guix, Rosa M. PintóAbstract:Human Astrovirus nonstructural C-terminal nsP1a protein (nsP1a/4) colocalizes with the endoplasmic reticulum and viral RNA. It has been suggested that nsP1a/4 protein is involved in the RNA replication process in endoplasmic reticulum-derived intracellular membranes. A hypervariable region (HVR) is contained in the nsP1a/4 protein, and different replicative patterns can be distinguished depending on its variability. In the present work, both the Astrovirus RNA-dependent RNA polymerase and four types (IV, V, VI, and XII) of nsP1a/4 proteins have been cloned and expressed in the baculovirus system to analyze their interactions. Different isoforms of each of the nsP1a/4 proteins exist: a nonphosphorylated isoform and different phosphorylated isoforms. While the polymerase accumulates as a monomer, the nsP1a/4 proteins accumulate as oligomers. The oligomerization domain of nsP1a/4-V is mapped between residues 176 and 209. For all studied genotypes, oligomers mainly contain the nonphosphorylated isoform. When RNA polymerase is coexpressed with nsP1a/4 proteins, they interact, likely forming heterodimers. The polymerase binding region has been mapped in the nsP1a/4-V protein between residues 88 and 176. Phosphorylated isoforms of nsP1a/4 type VI show a stronger interactive pattern with the polymerase than the nonphosphorylated isoform. This difference is not observed in genotypes IV and V, suggesting a role of the HVR in modulating the interaction of the nsP1a/4 protein with the polymerase through phosphorylation/dephosphorylation of some critical residues.
Suzanne M. Matsui - One of the best experts on this subject based on the ideXlab platform.
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2016Co-Authors: Ute Geigenmu Ller, N. Ginzton, Suzanne M. MatsuiAbstract:Studies on intracellular processing of the capsid protein of Human Astrovirus serotype 1 in infected cell
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immature and mature Human Astrovirus structure conformational changes and similarities to hepatitis e virus
Journal of Molecular Biology, 2012Co-Authors: Kelly A. Dryden, Ernesto Mendez, Suzanne M. Matsui, Mark Yeager, Mariana Tihova, Norbert NowotnyAbstract:Human Astroviruses (HAstVs) are a major cause of gastroenteritis. HAstV assembles from the structural protein VP90 and undergoes a cascade of proteolytic cleavages. Cleavage to VP70 is required for release of immature particles from cells, and subsequent cleavage by trypsin confers infectivity. We used electron cryomicroscopy and icosahedral image analysis to determine the first experimentally derived, three-dimensional structures of an immature VP70 virion and a fully proteolyzed, infectious virion. Both particles display T=3 icosahedral symmetry and nearly identical solid capsid shells with diameters of ~350A. Globular spikes emanate from the capsid surface, yielding an overall diameter of ~440A. While the immature particles display 90 dimeric spikes, the mature capsid only displays 30 spikes, located on the icosahedral 2-fold axes. Loss of the 60 peripentonal spikes likely plays an important role in viral infectivity. In addition, immature HAstV bears a striking resemblance to the structure of hepatitis E virus (HEV)-like particles, as previously predicted from structural similarity of the crystal structure of the Astrovirus spike domain with the HEV P-domain [Dong, J., Dong, L., Mendez, E. & Tao, Y. (2011). Crystal structure of the Human Astrovirus capsid spike. Proc. Natl. Acad. Sci. USA108, 12681-12686]. Similarities between their capsid shells and dimeric spikes and between the sequences of their capsid proteins suggest that these viral families are phylogenetically related and may share common assembly and activation mechanisms.
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V, 1.Studies on the molecular biology of Human Astrovirus
Perspectives in Medical Virology, 2003Co-Authors: Ute Geigenmüller, Ernesto Mendez, Suzanne M. MatsuiAbstract:Publisher Summary This chapter briefly reviews the genomic organization and replication strategy of Astrovirus. It discusses each of the known viral proteins in detail, focusing on the data obtained for Human Astrovirus serotypes 1 and 8 (HAstV-1 and HAstV-8) in the context of the general literature on the astroviral molecular biology. The genomic RNA contains three long open reading frames: ORF1a, ORF1b, and ORF2. The proposed replication strategy for Astrovirus has in large part been inferred from the well-characterized life cycle of the enveloped alphaviruses that show a genome organization and strategy for expression of the structural protein(s) similar to the Astroviruses. Specifically, upon infection, nsPla and nsPlb are believed to be translated directly from the input-positive strand viral genome. The newly synthesized nsPs then enable the transcription of a full-length negative-strand RNA that subsequently serves as the template for the transcription of new plus strand genomic RNA and subgenomic RNA. Based on this replication strategy, and by analogy to the eukaryotic expression vectors that have been developed from several of the alphaviruses, Astrovirus can be used to express a foreign protein.
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Studies on intracellular processing of the capsid protein of Human Astrovirus serotype 1 in infected cells.
Journal of General Virology, 2002Co-Authors: Ute Geigenmüller, N. Ginzton, Suzanne M. MatsuiAbstract:Astroviruses are non-enveloped, positive-strand RNA viruses. Their structural (capsid) protein is processed extracellularly into several smaller fragments which are found on the mature viral particle. In addition, intracellular cleavage of the capsid protein has been proposed. However, analysis of capsid protein processing has been hampered by the lack of antibodies to regions near the N and C termini of the protein. Here we describe the construction of two infectious mutants of Human Astrovirus serotype 1 (HAstV-1), in which amino acids (aa) 11–30 or aa 783–787, respectively, of the 787 aa capsid protein were replaced by tag sequences. Processing of the tagged capsid proteins in infected Caco-2 cells was analysed by immunoprecipitation with specific reagents directed against the tags or against native internal regions of the capsid protein. No intracellular processing of the capsid protein in infected cells could be detected, while assembled viral particles were readily observed within cells.
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processing of nonstructural protein 1a of Human Astrovirus
Journal of Virology, 2002Co-Authors: Ute Geigenmüller, N. Ginzton, Teri Chew, Suzanne M. MatsuiAbstract:Astrovirus contains three open reading frames (ORF) on its genomic RNA, ORF1a, ORF1b, and ORF2. ORF1a encodes a 920-amino-acid (aa) nonstructural protein, nsP1a, which displays a 3C-like serine protease motif. Little is known about the processing of nsP1a or whether the protease it contains is active and involved in autocatalytic processing. Here we address both of these matters. Intact and N-terminally deleted forms of ORF1a from Human Astrovirus serotype 1 were expressed in BHK cells, and nsP1a-derived processing products were immunoprecipitated with an nsP1a-specific antibody or an antibody specific for an N-terminally linked epitope tag. The mapping of the main processing products, p20 and p27, suggests cleavage sites near aa 170, 410, and 655 of nsP1a. Cleavages at around aa 410 and 655, but not aa 170, were abolished when a 9-aa substitution was introduced into the protease motif in nsP1a. The p27 processing product was also found in Caco-2 cells that had been infected with Human Astrovirus serotype 1, confirming the presence of the cleavage sites at approximately aa 410 and 655.