The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Stanley M. Lemon - One of the best experts on this subject based on the ideXlab platform.

  • Hepatovirus 3ABC proteases and evolution of mitochondrial antiviral signaling protein (MAVS)
    Journal of hepatology, 2019
    Co-Authors: Hui Feng, Jan Felix Drexler, Anna-lena Sander, Andres Moreira-soto, Daisuke Yamane, Stanley M. Lemon
    Abstract:

    Background & Aims Unlike other hepatitis viruses that have infected primates for millions of years, hepatitis A virus (HAV) likely entered human populations only 10–12 thousand years ago after jumping from a rodent host. The phylogeny of modern Hepatoviruses that infect rodents and bats suggest that multiple similar host shifts have occurred in the past. The factors determining such shifts are unknown, but the capacity to overcome innate antiviral responses in a foreign species is likely key. Methods We assessed the capacity of diverse Hepatovirus 3ABC proteases to cleave mitochondrial antiviral signaling protein (MAVS) and disrupt antiviral signaling in HEK293 and human hepatocyte-derived cell lines. We also applied maximum-likelihood and Bayesian algorithms to identify sites of diversifying selection in MAVS orthologs from 75 chiropteran, rodent and primate species. Results 3ABC proteases from bat, but not rodent Hepatoviruses efficiently cleaved human MAVS at Glu463/Gly464, disrupting virus activation of the interferon-β promoter, whereas human HAV 3ABC cleaved at Gln427/Val428. In contrast, MAVS orthologs from rodents and bats were resistant to cleavage by 3ABC proteases of cognate Hepatoviruses and in several cases human HAV. A search for diversifying selection among MAVS orthologs from all 3 orders revealed 90 of ∼540 residues to be under positive selection, including residues in chiropteran MAVS that align with the site of cleavage of human MAVS by bat 3ABC proteases. Conclusions 3ABC protease cleavage of MAVS is a conserved attribute of Hepatoviruses, acting broadly across different mammalian species and associated with evidence of diversifying selection at cleavage sites in rodent and bat MAVS orthologs. The capacity of Hepatoviruses to disrupt MAVS-mediated innate immune responses has shaped evolution of both Hepatoviruses and their hosts, and facilitates cross-species transmission of hepatitis A. Lay summary Hepatitis A virus, a common cause of acute hepatitis globally, is likely to have evolved from a virus that jumped from a rodent species to humans within the last 10–12 thousand years. Here we show that distantly related Hepatoviruses, that infect bats and rodents today, express proteases that disrupt innate antiviral responses in human cells. This conserved attribute of Hepatoviruses may have contributed to that ancient host species shift.

  • Hepatitis A Virus Genome Organization and Replication Strategy
    Cold Spring Harbor perspectives in medicine, 2018
    Co-Authors: Kevin L. Mcknight, Stanley M. Lemon
    Abstract:

    Hepatitis A virus (HAV) is a positive-strand RNA virus classified in the genus Hepatovirus of the family Picornaviridae It is an ancient virus with a long evolutionary history and multiple features of its capsid structure, genome organization, and replication cycle that distinguish it from other mammalian picornaviruses. HAV proteins are produced by cap-independent translation of a single, long open reading frame under direction of an inefficient, upstream internal ribosome entry site (IRES). Genome replication occurs slowly and is noncytopathic, with transcription likely primed by a uridylated protein primer as in other picornaviruses. Newly produced quasi-enveloped virions (eHAV) are released from cells in a nonlytic fashion in a unique process mediated by interactions of capsid proteins with components of the host cell endosomal sorting complexes required for transport (ESCRT) system.

  • Redundant Late Domain Functions of Tandem VP2 YPX3L Motifs in Nonlytic Cellular Egress of Quasi-enveloped Hepatitis A Virus
    Journal of Virology, 2018
    Co-Authors: Olga González-lópez, Efraín E. Rivera-serrano, Lucinda L. Hensley, Kevin L. Mcknight, Jingshan Ren, David I. Stuart, Elizabeth E. Fry, Stanley M. Lemon
    Abstract:

    The quasi-envelopment of hepatitis A virus (HAV) capsids in exosome-like virions (eHAV) is an important but incompletely understood aspect of the Hepatovirus life cycle. This process is driven by recruitment of newly assembled capsids to endosomal vesicles into which they bud to form multivesicular bodies with intraluminal vesicles that are later released at the plasma membrane as eHAV. The endosomal sorting complexes required for transport (ESCRT) are key to this process, as is the ESCRT-III-associated protein, ALIX, which also contributes to membrane budding of conventional enveloped viruses. YPX1or3L late domains in the structural proteins of these viruses mediate interactions with ALIX, and two such domains exist in the HAV VP2 capsid protein. Mutational studies of these domains are confounded by the fact that the Tyr residues (important for interactions of YPX1or3L peptides with ALIX) are required for efficient capsid assembly. However, single Leu-to-Ala substitutions within either VP2 YPX3L motif (L1-A and L2-A mutants) were well tolerated, albeit associated with significantly reduced eHAV release. In contrast, simultaneous substitutions in both motifs (L1,2-A) eliminated virus release but did not inhibit assembly of infectious intracellular particles. Immunoprecipitation experiments suggested that the loss of eHAV release was associated with a loss of ALIX recruitment. Collectively, these data indicate that HAV YPX3L motifs function as redundant late domains during quasi-envelopment and viral release. Since these motifs present little solvent-accessible area in the crystal structure of the naked extracellular capsid, the capsid structure may be substantially different during quasi-envelopment.IMPORTANCE Nonlytic release of hepatitis A virus (HAV) as exosome-like quasi-enveloped virions is a unique but incompletely understood aspect of the Hepatovirus life cycle. Several lines of evidence indicate that the host protein ALIX is essential for this process. Tandem YPX3L "late domains" in the VP2 capsid protein could be sites of interaction with ALIX, but they are not accessible on the surface of an X-ray model of the extracellular capsid, raising doubts about this putative late domain function. Here, we describe YPX3L domain mutants that assemble capsids normally but fail to bind ALIX and be secreted as quasi-enveloped eHAV. Our data support late domain function for the VP2 YPX3L motifs and raise questions about the structure of the HAV capsid prior to and following quasi-envelopment.

  • Protein composition of the hepatitis A virus quasi-envelope.
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: Kevin L. Mcknight, Olga González-lópez, Efraín E. Rivera-serrano, Ling Xie, Xian Chen, Stanley M. Lemon
    Abstract:

    The Picornaviridae are a diverse family of RNA viruses including many pathogens of medical and veterinary importance. Classically considered "nonenveloped," recent studies show that some picornaviruses, notably hepatitis A virus (HAV; genus Hepatovirus) and some members of the Enterovirus genus, are released from cells nonlytically in membranous vesicles. To better understand the biogenesis of quasi-enveloped HAV (eHAV) virions, we conducted a quantitative proteomics analysis of eHAV purified from cell-culture supernatant fluids by isopycnic ultracentrifugation. Amino acid-coded mass tagging (AACT) with stable isotopes followed by tandem mass spectrometry sequencing and AACT quantitation of peptides provided unambiguous identification of proteins associated with eHAV versus unrelated extracellular vesicles with similar buoyant density. Multiple peptides were identified from HAV capsid proteins (53.7% coverage), but none from nonstructural proteins, indicating capsids are packaged as cargo into eHAV vesicles via a highly specific sorting process. Other eHAV-associated proteins (n = 105) were significantly enriched for components of the endolysosomal system (>60%, P < 0.001) and included many common exosome-associated proteins such as the tetraspanin CD9 and dipeptidyl peptidase 4 (DPP4) along with multiple endosomal sorting complex required for transport III (ESCRT-III)-associated proteins. Immunoprecipitation confirmed that DPP4 is displayed on the surface of eHAV produced in cell culture or present in sera from humans with acute hepatitis A. No LC3-related peptides were identified by mass spectrometry. RNAi depletion studies confirmed that ESCRT-III proteins, particularly CHMP2A, function in eHAV biogenesis. In addition to identifying surface markers of eHAV vesicles, the results support an exosome-like mechanism of eHAV egress involving endosomal budding of HAV capsids into multivesicular bodies.

  • Identification of a Conserved RNA Replication Element (cre) within the 3Dpol-Coding Sequence of Hepatoviruses
    Journal of virology, 2008
    Co-Authors: Yan Yang, David J.a. Evans, Peter Simmonds, Stanley M. Lemon
    Abstract:

    Internally located, cis-acting RNA replication elements (cre) have been identified within the genomes of viruses representing each of the major picornavirus genera (Enterovirus, Rhinovirus, Aphthovirus, and Cardiovirus) except Hepatovirus. Previous efforts to identify a stem-loop structure with cre function in hepatitis A virus (HAV), the type species of this genus, by phylogenetic analyses or thermodynamic predictions have not succeeded. However, a region of markedly suppressed synonymous codon variability was identified in alignments of HAV sequences near the 5' end of the 3D(pol)-coding sequence of HAV, consistent with noncoding constraints imposed by an underlying RNA secondary structure. Subsequent MFOLD predictions identified a 110-nucleotide (nt) complex stem-loop in this region with a typical AAACA/G cre motif in its top loop. A potentially homologous RNA structure was identified in this region of the avian encephalitis virus genome, despite little nucleotide sequence relatedness between it and HAV. Mutations that disrupted secondary RNA structure or the AAACA/G motif, without altering the amino acid sequence of 3D(pol), ablated replication of a subgenomic HAV replicon in transfected human hepatoma cells. Replication competence could be rescued by reinsertion of the native 110-nt stem-loop structure (but not an abbreviated 45-nt stem-loop) upstream of the HAV coding sequence in the replicon. These results suggest that this stem-loop is functionally similar to cre elements of other picornaviruses and likely involved in templating VPg uridylylation as in other picornaviruses, despite its significantly larger size and lower free folding energy.

Rosa M. Pintó - One of the best experts on this subject based on the ideXlab platform.

  • Hepatitis A virus evolution and the potential emergence of new variants escaping the presently available vaccines
    Future microbiology, 2012
    Co-Authors: Rosa M. Pintó, Lucía D’andrea, Francisco J. Pérez-rodriguez, M. Isabel Costafreda, Enric Ribes, Susana Guix, Albert Bosch
    Abstract:

    Hepatitis A is the most common infection of the liver worldwide and is fecal–orally transmitted. Its incidence tends to decrease with improvements in hygiene conditions but at the same time its severity increases. Hepatitis A virus is the causative agent of acute hepatitis in humans and belongs to the Hepatovirus genus in the Picornaviridae family, and it has very unique characteristics. This article reviews some molecular and biological properties that allow the virus to live in a very quiescent way and to build an extremely stable capsid that is able to persist in and out of the body. Additionally, the relationship between the genomic composition and the structural and antigenic properties of the capsid is discussed, and the potential emergence of antigenic variants is evaluated from an evolutionary perspective.

  • fine tuning translation kinetics selection as the driving force of codon usage bias in the hepatitis a virus capsid
    PLOS Pathogens, 2010
    Co-Authors: Lluis Aragones, Susana Guix, Enric Ribes, Albert Bosch, Rosa M. Pintó
    Abstract:

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellular changing conditions in order to recover the original fitness.

  • Codon usage and replicative strategies of hepatitis A virus
    Virus research, 2007
    Co-Authors: Rosa M. Pintó, M. Isabel Costafreda, Enric Ribes, Lluis Aragones, Albert Bosch
    Abstract:

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has many biological characteristics that distinguish it from other members of the Picornaviridae family. Among these it is worth of note the need for an intact eIF4G factor for the initiation of translation and thus the inability to shut down host protein synthesis by a similar mechanism as in other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition HAV has strategically adopted a naturally highly deoptimized codon usage. Accordingly, a low protein synthesis may be expected with those proteins involved in RNA replication existing at limiting concentrations. Thus, a very low translation rate and a very low RNA replication rate may play a role in escaping to host cell defenses, allowing the virus to grow in a quiescent way. This could explain the high specific infectivity of HAV in spite of its naturally deoptimized codon usage, which would indicate non-abortive infections due to the antiviral cell response. Additionally, the deoptimized codon usage conveys in the use of abundant and rare codons. Many clusters of such rare codons are present in the capsid surface playing a seminal role in the highly cohesive stability of the HAV virion. Thus, the slow translation rate, resulting from the accumulation of rare codons, is likely to contribute to the highly stable viral capsid necessary for a prolonged survival outside the host body.

Albert Bosch - One of the best experts on this subject based on the ideXlab platform.

  • RM: Fine-tuning translation kinetics selection as the driving force of codon usage bias in the hepatitis A virus capsid. PLoS Pathog 2010
    2016
    Co-Authors: Susana Guix, Enric Ribes, Albert Bosch, Rosa M. Pintó
    Abstract:

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellula

  • Hepatitis A virus evolution and the potential emergence of new variants escaping the presently available vaccines
    Future microbiology, 2012
    Co-Authors: Rosa M. Pintó, Lucía D’andrea, Francisco J. Pérez-rodriguez, M. Isabel Costafreda, Enric Ribes, Susana Guix, Albert Bosch
    Abstract:

    Hepatitis A is the most common infection of the liver worldwide and is fecal–orally transmitted. Its incidence tends to decrease with improvements in hygiene conditions but at the same time its severity increases. Hepatitis A virus is the causative agent of acute hepatitis in humans and belongs to the Hepatovirus genus in the Picornaviridae family, and it has very unique characteristics. This article reviews some molecular and biological properties that allow the virus to live in a very quiescent way and to build an extremely stable capsid that is able to persist in and out of the body. Additionally, the relationship between the genomic composition and the structural and antigenic properties of the capsid is discussed, and the potential emergence of antigenic variants is evaluated from an evolutionary perspective.

  • fine tuning translation kinetics selection as the driving force of codon usage bias in the hepatitis a virus capsid
    PLOS Pathogens, 2010
    Co-Authors: Lluis Aragones, Susana Guix, Enric Ribes, Albert Bosch, Rosa M. Pintó
    Abstract:

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has several unique biological characteristics that distinguish it from other members of the Picornaviridae family. Among these, the need for an intact eIF4G factor for the initiation of translation results in an inability to shut down host protein synthesis by a mechanism similar to that of other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition, HAV has strategically adopted a naturally highly deoptimized codon usage with respect to that of its cellular host. With the aim to optimize its codon usage the virus was adapted to propagate in cells with impaired protein synthesis, in order to make tRNA pools more available for the virus. A significant loss of fitness was the immediate response to the adaptation process that was, however, later on recovered and more associated to a re-deoptimization rather than to an optimization of the codon usage specifically in the capsid coding region. These results exclude translation selection and instead suggest fine-tuning translation kinetics selection as the underlying mechanism of the codon usage bias in this specific genome region. Additionally, the results provide clear evidence of the Red Queen dynamics of evolution since the virus has very much evolved to re-adapt its codon usage to the environmental cellular changing conditions in order to recover the original fitness.

  • Codon usage and replicative strategies of hepatitis A virus
    Virus research, 2007
    Co-Authors: Rosa M. Pintó, M. Isabel Costafreda, Enric Ribes, Lluis Aragones, Albert Bosch
    Abstract:

    Hepatitis A virus (HAV), the prototype of genus Hepatovirus, has many biological characteristics that distinguish it from other members of the Picornaviridae family. Among these it is worth of note the need for an intact eIF4G factor for the initiation of translation and thus the inability to shut down host protein synthesis by a similar mechanism as in other picornaviruses. Consequently, HAV must inefficiently compete for the cellular translational machinery and this may explain its poor growth in cell culture. In this context of virus/cell competition HAV has strategically adopted a naturally highly deoptimized codon usage. Accordingly, a low protein synthesis may be expected with those proteins involved in RNA replication existing at limiting concentrations. Thus, a very low translation rate and a very low RNA replication rate may play a role in escaping to host cell defenses, allowing the virus to grow in a quiescent way. This could explain the high specific infectivity of HAV in spite of its naturally deoptimized codon usage, which would indicate non-abortive infections due to the antiviral cell response. Additionally, the deoptimized codon usage conveys in the use of abundant and rare codons. Many clusters of such rare codons are present in the capsid surface playing a seminal role in the highly cohesive stability of the HAV virion. Thus, the slow translation rate, resulting from the accumulation of rare codons, is likely to contribute to the highly stable viral capsid necessary for a prolonged survival outside the host body.

Gabor Reuter - One of the best experts on this subject based on the ideXlab platform.

  • genome analysis of a novel highly divergent picornavirus from common kestrel falco tinnunculus the first non enteroviral picornavirus with type i like ires
    Infection Genetics and Evolution, 2015
    Co-Authors: Akos Boros, Peter Pankovics, Peter Simmonds, Edit Pollak, Robert Matics, Tung Gia Phan, Eric Delwart, Gabor Reuter
    Abstract:

    Although the number of identified avian-borne picornaviruses (family Picornaviridae) is continuously increasing there remains several species-rich avian host groups, such as the order Falconiformes (with 290 bird species) from which picornaviruses have not been identified. This study reports the first complete genome of a novel, highly divergent picornavirus, named as Falcovirus A1 (KP230449), from the carnivorous bird, the common kestrel (Falco tinnunculus, order Falconiformes). Falcovirus A1 has the longest 3DRdRp genome region and distant phylogenetic relationship to the Hepatitis A virus 1 (Hepatovirus) and Avian encephalomyelitis virus 1 (Tremovirus). It has a type-I (enterovirus-like) IRES in the 5′UTR – identified for the first time among avian-borne picornaviruses suggesting that type-I IRES is not restricted only to enteroviruses and providing further evidence of mosaicism of this region among different picornavirus genera.

  • Genome analysis of a novel, highly divergent picornavirus from common kestrel (Falco tinnunculus): The first non-enteroviral picornavirus with type-I-like IRES
    Infection genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 2015
    Co-Authors: Akos Boros, Peter Pankovics, Peter Simmonds, Edit Pollak, Robert Matics, Tung Gia Phan, Eric Delwart, Gabor Reuter
    Abstract:

    Although the number of identified avian-borne picornaviruses (family Picornaviridae) is continuously increasing there remains several species-rich avian host groups, such as the order Falconiformes (with 290 bird species) from which picornaviruses have not been identified. This study reports the first complete genome of a novel, highly divergent picornavirus, named as Falcovirus A1 (KP230449), from the carnivorous bird, the common kestrel (Falco tinnunculus, order Falconiformes). Falcovirus A1 has the longest 3D(RdRp) genome region and distant phylogenetic relationship to the Hepatitis A virus 1 (Hepatovirus) and Avian encephalomyelitis virus 1 (Tremovirus). It has a type-I (enterovirus-like) IRES in the 5'UTR - identified for the first time among avian-borne picornaviruses suggesting that type-I IRES is not restricted only to enteroviruses and providing further evidence of mosaicism of this region among different picornavirus genera.

  • Kobuvirus in domestic sheep, Hungary.
    Emerging infectious diseases, 2010
    Co-Authors: Gabor Reuter, Akos Boros, Peter Pankovics, László Egyed
    Abstract:

    To the Editor: Picornaviruses (family Picornaviridae) are small, nonenveloped viruses with single-stranded, positive-sense genomic RNA. They are divided into 12 genera: Enterovirus, Aphthovirus, Cardiovirus, Hepatovirus, Parechovirus, Erbovirus, Teschovirus, Sapelovirus, Senecavirus, Tremovirus, AviHepatovirus, and Kobuvirus. The genus Kobuvirus consists of 2 officially recognized species, Aichi virus (1) and Bovine kobuvirus (2), and 1 candidate species, porcine kobuvirus (3). The kobuvirus genome is ≈8.2–8.4 kb long and has the typical picornavirus genome organization of leader (L) protein following the structural (viral protein [VP] 0, VP3, and VP1) and nonstructural (2A–2C and 3A–3D) regions (2,4). The genetic identity on the coding region between Aichi (strain A846/88), bovine (U-1), and porcine (S-1-HUN) viruses is between 35% (L protein) and 74% (3D region) (2,4). Aichi virus and bovine kobuvirus were first detected in fecal samples from humans and cattle in Japan, in 1991 and 2003, respectively (1,2). Porcine kobuvirus was identified from domestic pigs in Hungary in 2008 (3,4). Recent studies demonstrated that Aichi virus circulates in Asia (5), Europe (6,7) including Hungary (4), South America (6), and North Africa (8) and can cause gastroenteritis in humans. In addition, bovine and porcine kobuviruses are detected among these farm animals in Europe (4) and Asia (2,9). These data indicate that kobuviruses are widely distributed geographically and raise the possibility of additional animal host species. We detected kobuvirus in sheep. On March 17, 2009, a total of 8 fecal samples were collected from young, healthy, domestic sheep (Ovis aries)

  • Bovine kobuvirus in europe.
    Emerging infectious diseases, 2009
    Co-Authors: Gabor Reuter, László Egyed
    Abstract:

    To the Editor: Picornaviruses (family Picornaviridae) are small, nonenveloped viruses with single-stranded, positive-sense genomic RNA. Picornaviruses are currently divided into 8 genera: Enterovirus, Aphthovirus, Cardiovirus, Hepatovirus, Parechovirus, Erbovirus, Teschovirus, and Kobuvirus (1). To date, the genus Kobuvirus consists of 2 officially recognized species, Aichi virus and Bovine kobuvirus, and 1 porcine kobuvirus as a candidate species (2–4). Aichi virus (strain A846/88) was first isolated in 1991 from feces of a person with acute gastroenteritis (2). Bovine kobuvirus (strain U-1) was detected in 2003 in bovine serum and fecal samples from clinically healthy cattle (3); in 2008, it was isolated from cattle with diarrhea (5). Aichi virus and bovine kobuvirus were first isolated in Japan. Porcine kobuvirus (strain S-1-HUN) was recently identified from domestic pigs in Hungary (4). Aichi viruses have been also detected in other countries in Asia (6), Europe (7,8), South America (7), and northern Africa (9). Bovine kobuvirus, however, has not been detected outside Asia (Japan and Thailand) (3,5).

  • Candidate New Species of Kobuvirus in Porcine Hosts
    Emerging infectious diseases, 2008
    Co-Authors: Gabor Reuter, Ákos Boldizsár, István Kiss, Peter Pankovics
    Abstract:

    To the Editor: Picornaviruses (family Picornaviridae) are small, nonenveloped viruses with single-stranded, positive-sense genomic RNA, currently divided into 8 genera: Enterovirus, Aphthovirus, Cardiovirus, Hepatovirus, Parechovirus, Erbovirus, Teschovirus, and Kobuvirus (1). To date, the genus Kobuvirus consists of 2 species, Aichi virus and Bovine kobuvirus, each possessing 1 serotype. Aichi virus (strain A846/88) was first isolated from a stool sample obtained from a person with acute gastroenteritis in 1991 (2). Bovine kobuvirus (strain U-1) was detected in bovine sera and in feces samples from clinically healthy cattle in 2003 (3). Human and bovine kobuviruses were first isolated in Japan. Recently, kobuviruses have also been detected in humans in other countries in Asia (4), Europe (5,6), and South America (5) and in calves with diarrhea in Thailand (7). The Aichi virus and bovine kobuvirus genomes are approximately 8.2–8.3 kb, respectively, and both have a typical picornavirus genome organization, including the L protein following structural (VP0, VP3, and VP1) and nonstructural (2A–2C and 3A–3D) regions (1,3). Genetic identity between Aichi and U-1 viruses ranges from 47.7% (3′ untranslated region) through 70.8% (3D region) (3). In this study, we report a new candidate species of kobuvirus. Porcine kobuvirus was serendipitously detected in fecal samples from domestic pigs in Hungary. Fecal samples were collected in February 2007 from 15 healthy piglets (Sus scrofa domestica) 2 species (1). Our study reports detection of kobuvirus in domestic pigs. Serendipitously, the generic calicivirus primers p289 and p290, designed for a calicivirus RNA-dependent RNA polymerase region, amplified a kobuvirus 3C/3D region when specimens were tested for porcine caliciviruses by RT-PCR. Comparison of the primers p289 and p290 and the S-1-HUN sequence showed that there are 12- and 11-bp homologous regions between the kobuvirus and the 3′ end of the primer sequences, respectively. Reverse primer p289 designed for calicivirus (norovirus and sapovirus) conserved amino acid 3D motif YGDD, which is also present in kobuviruses. All apparently healthy animals

John M. Cullen - One of the best experts on this subject based on the ideXlab platform.

  • TIM1 (HAVCR1) Is Not Essential for Cellular Entry of Either Quasi-enveloped or Naked Hepatitis A Virions.
    mBio, 2017
    Co-Authors: Anshuman Das, Olga González-lópez, Lucinda L. Hensley, Asuka Hirai-yuki, Bethany A. Rhein, Sven Moller-tank, Rachel B. Brouillette, Ichiro Misumi, William Lovell, John M. Cullen
    Abstract:

    Receptor molecules play key roles in the cellular entry of picornaviruses, and TIM1 (HAVCR1) is widely accepted to be the receptor for hepatitis A virus (HAV), an unusual, hepatotropic human picornavirus. However, its identification as the Hepatovirus receptor predated the discovery that Hepatoviruses undergo nonlytic release from infected cells as membrane-cloaked, quasi-enveloped HAV (eHAV) virions that enter cells via a pathway distinct from naked, nonenveloped virions. We thus revisited the role of TIM1 in Hepatovirus entry, examining both adherence and infection/replication in cells with clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-engineered TIM1 knockout. Cell culture-derived, gradient-purified eHAV bound Huh-7.5 human hepatoma cells less efficiently than naked HAV at 4°C, but eliminating TIM1 expression caused no difference in adherence of either form of HAV, nor any impact on infection and replication in these cells. In contrast, TIM1-deficient Vero cells showed a modest reduction in quasi-enveloped eHAV (but not naked HAV) attachment and replication. Thus, TIM1 facilitates quasi-enveloped eHAV entry in Vero cells, most likely by binding phosphatidylserine (PtdSer) residues on the eHAV membrane. Both Tim1-/-Ifnar1-/- and Tim4-/-Ifnar1-/- double-knockout mice were susceptible to infection upon intravenous challenge with infected liver homogenate, with fecal HAV shedding and serum alanine aminotransferase (ALT) elevations similar to those in Ifnar1-/- mice. However, intrahepatic HAV RNA and ALT elevations were modestly reduced in Tim1-/-Ifnar1-/- mice compared to Ifnar1-/- mice challenged with a lower titer of gradient-purified HAV or eHAV. We conclude that TIM1 is not an essential Hepatovirus entry factor, although its PtdSer-binding activity may contribute to the spread of quasi-enveloped virus and liver injury in mice.IMPORTANCE T cell immunoglobulin and mucin-containing domain protein 1 (TIM1) was reported more than 2 decades ago to be an essential cellular receptor for hepatitis A virus (HAV), a picornavirus in the Hepatovirus genus, resulting in its designation as "hepatitis A virus cellular receptor 1" (HAVCR1) by the Human Genome Organization Gene Nomenclature Committee. However, recent studies have shown that HAV exists in nature as both naked, nonenveloped (HAV) virions and membrane-cloaked, quasi-enveloped infectious virus (eHAV), prompting us to revisit the role of TIM1 in viral entry. We show here that TIM1 (HAVCR1) is not an essential cellular receptor for HAV entry into cultured cells or required for viral replication and pathogenesis in permissive strains of mice, although it may facilitate early stages of infection by binding phosphatidylserine on the eHAV surface. This work thus corrects the published record and sets the stage for future efforts to identify specific Hepatovirus entry factors.

  • TIM1 (HAVCR1) Is Not Essential for Cellular Entry of Either Quasi-enveloped or Naked Hepatitis A Virions
    American Society for Microbiology, 2017
    Co-Authors: Anshuman Das, Asuka Hirai-yuki, Bethany A. Rhein, Sven Moller-tank, Rachel B. Brouillette, Ichiro Misumi, William Lovell, Olga González-láópez, Lucinda Hensley, John M. Cullen
    Abstract:

    Receptor molecules play key roles in the cellular entry of picornaviruses, and TIM1 (HAVCR1) is widely accepted to be the receptor for hepatitis A virus (HAV), an unusual, hepatotropic human picornavirus. However, its identification as the Hepatovirus receptor predated the discovery that Hepatoviruses undergo nonlytic release from infected cells as membrane-cloaked, quasi-enveloped HAV (eHAV) virions that enter cells via a pathway distinct from naked, nonenveloped virions. We thus revisited the role of TIM1 in Hepatovirus entry, examining both adherence and infection/replication in cells with clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-engineered TIM1 knockout. Cell culture-derived, gradient-purified eHAV bound Huh-7.5 human hepatoma cells less efficiently than naked HAV at 4°C, but eliminating TIM1 expression caused no difference in adherence of either form of HAV, nor any impact on infection and replication in these cells. In contrast, TIM1-deficient Vero cells showed a modest reduction in quasi-enveloped eHAV (but not naked HAV) attachment and replication. Thus, TIM1 facilitates quasi-enveloped eHAV entry in Vero cells, most likely by binding phosphatidylserine (PtdSer) residues on the eHAV membrane. Both Tim1−/− Ifnar1−/− and Tim4−/− Ifnar1−/− double-knockout mice were susceptible to infection upon intravenous challenge with infected liver homogenate, with fecal HAV shedding and serum alanine aminotransferase (ALT) elevations similar to those in Ifnar1−/− mice. However, intrahepatic HAV RNA and ALT elevations were modestly reduced in Tim1−/−Ifnar1−/− mice compared to Ifnar1−/− mice challenged with a lower titer of gradient-purified HAV or eHAV. We conclude that TIM1 is not an essential Hepatovirus entry factor, although its PtdSer-binding activity may contribute to the spread of quasi-enveloped virus and liver injury in mice