The Experts below are selected from a list of 747 Experts worldwide ranked by ideXlab platform

Mary K. Estes - One of the best experts on this subject based on the ideXlab platform.

  • Norwalk virus vaccines: challenges and progress
    2016
    Co-Authors: Mary K. Estes, Mark A Gilger, Susan S Pacheco, Judith M. Ball, Roberto A. Guerrero, Antone R. Opekun, David Y. Graham
    Abstract:

    Human Caliciviruses (HuCVs) are the major cause of outbreaks of acute nonbacterial gastro-enteritis throughout the world. An increasing recognition of the clinical signi®cance of these viruses as Human pathogens causing foodborne and waterborne disease indicates that an effective vaccine would be useful. This article reviews the current challenges that exist for the development of a vaccine for the HuCVs as well as the status of development of a candidate vaccine. HuCVs are viruses that exhibit a restricted tropism for infection of the gastrointestinal tract of Humans, and a volunteer model of infection and disease is available. As pathogens with a restricted host range, the HuCVs are excellent models for understanding the mechanisms that mediate and regulate viral infection of the gastrointestinal tract and mucosal immunity in Humans. Norwalk virus (NV), a prototype virus in the ªNorwalk-like virusº (NLV) genus of the family Caliciviridae causes acute epidemic gastroenteritis in Humans of all ages in both developed and developing countries [1]. Norwalk and Norwalk-like hu-man Caliciviruses (HuCVs) are spread by ingestion of contam

  • Caliciviridae and Astroviridae.
    Cellular Signaling and Innate Immune Responses to RNA Virus Infections, 2014
    Co-Authors: Susana Guix, Mary K. Estes
    Abstract:

    Caliciviruses and astroviruses, along with rotavirus, are regarded as important causes of viral gastroenteritis. Surveillance studies using recently developed molecular diagnostic methods have also highlighted the importance of Human astroviruses and other underreported pathogens as important causes of pediatric acute gastroenteritis. Epidemiological information on Human Caliciviruses and astroviruses is providing data required to assess the economic burden of the disease and justify the development of prevention strategies, including vaccination. A section describes what is now known about the activation of innate responses after both Human and nonHuman calicivirus infections, and specifically emphasizes the effect that innate antiviral responses might have on restricting Human norovirus propagation in vitro. To date, the role of innate immunity in controlling infections caused by Caliciviruses has been demonstrated for murine norovirus (MNV) and porcine enteric calicivirus (PEC), but only limited data are available to confirm this for Human noroviruses. As positive-sense RNA viruses, there are several steps in the replication cycle of Caliciviruses and astroviruses where the cellular antiviral machinery could detect foreign viral components. Exploration of the interplay between Caliciviruses and astroviruses and the interferon (IFN) response not only will help us to better understand viral pathogenesis but also can result in novel vaccination strategies and therapies. This chapter concludes with a few remarks meant to stimulate discussion and future studies to better understand the interplay between calicivirus and astrovirus infections and the cellular antiviral responses.

  • R EPORTS X-ray Crystallographic Structure of the Norwalk Virus
    2014
    Co-Authors: B Venkataram V Prasad, Jordi Bella, Michael G. Rossmann, Michele E Hardy, Terje Dokl, Mary K. Estes
    Abstract:

    Norwalk virus, a noncultivatable Human calicivirus, is the major cause of epidemic gastroenteritis in Humans. The first x-ray structure of a calicivirus capsid, which consists of 180 copies of a single protein, has been determined by phase extension from a low-resolution electron microscopy structure. The capsid protein has a protruding (P) domain connected by a flexible hinge to a shell (S) domain that has a classical eight-stranded �-sandwich motif. The structure of the P domain is unlike that of any other viral protein with a subdomain exhibiting a fold similar to that of the second domain in the eukaryotic translation elongation factor–Tu. This subdomain, located at the exterior of the capsid, has the largest sequence variation among Norwalk-like Human Caliciviruses and is likely to contain the determinants of strain specificity and cell binding. Norwalk virus (NV) and Norwalk-like viruses (NLVs) are Human Caliciviruses (1) that account for over 96 % of outbreaks of acute

  • X-ray structure of a native calicivirus: structural insights into antigenic diversity and host specificity.
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: Rong Chen, John D. Neill, Mary K. Estes, B. V. Venkataram Prasad
    Abstract:

    Caliciviruses, grouped into four genera, are important Human and veterinary pathogens with a potential for zoonosis. In these viruses, capsid-related functions such as assembly, antigenicity, and receptor interactions are predominantly encoded in a single protein that forms an icosahedral capsid. Understanding of the immunologic functions and pathogenesis of Human Caliciviruses in the Norovirus and Sapovirus genera is hampered by the lack of a cell culture system or animal models. Much of our understanding of these viruses, including the structure, has depended on recombinant capsids. Here we report the atomic structure of a native calicivirus from the Vesivirus genus that exhibits a broad host range possibly including Humans and map immunological function onto a calicivirus structure. The vesivirus structure, despite a similar architectural design as seen in the recombinant norovirus capsid, exhibits novel features and indicates how the unique modular organization of the capsid protein with interdomain flexibility, similar to an antibody structure with a hinge and an elbow, integrates capsid-related functions and facilitates strain diversity in Caliciviruses. The internally located N-terminal arm participates in a novel network of interactions through domain swapping to assist the assembly of the shell domain into an icosahedral scaffold, from which the protruding domain emanates. Neutralization epitopes localize to three hypervariable loops in the distal portion of the protruding domain surrounding a region that exhibits host-specific conservation. These observations suggest a mechanism for antigenic diversity and host specificity in Caliciviruses and provide a structural framework for vaccine development.

  • the 3 end of norwalk virus mrna contains determinants that regulate the expression and stability of the viral capsid protein vp1 a novel function for the vp2 protein
    Journal of Virology, 2003
    Co-Authors: Andrea Bertolotticiarlet, Sue E Crawford, Anne M Hutson, Mary K. Estes
    Abstract:

    Norwalk virus (NV) is the prototype strain of a group of noncultivable Human Caliciviruses responsible for epidemic outbreaks of acute gastroenteritis. The capsid protein VP1 is synthesized from a subgenomic RNA that contains two open reading frames (ORFs), ORF2 and ORF3, and the 3′ untranslated region (UTR). ORF2 and ORF3 code for the capsid protein (VP1) and a small structural basic protein (VP2), respectively. We discovered that the yields of virus-like particles (VLPs) composed of VP1 are significantly reduced when this protein is expressed from ORF2 alone. To determine how the 3′ terminus of the NV subgenomic RNA regulates VP1 expression, we compared VP1 expression levels by using recombinant baculovirus constructs containing different 3′ elements. High VP1 levels were detected by using a recombinant baculovirus that contained ORF2, ORF3, and the 3′UTR (ORF2+3+3′UTR). In contrast, expression of VP1 from constructs that lacked the 3′UTR (ORF2+3), ORF3 (ORF2+3′UTR), or both (ORF2 alone) was highly reduced. Elimination of VP2 synthesis from the subgenomic RNA by mutation resulted in VP1 levels similar to those obtained with the ORF2 construct alone, suggesting a cis role for VP2 in upregulation of VP1 expression levels. Comparisons of the kinetics of RNA and capsid protein expression levels by using constructs with or without ORF3 or the 3′UTR revealed that the 3′UTR increased the levels of VP1 RNA, whereas the presence of VP2 resulted in increased levels of VP1. Furthermore, VP2 increased VP1 stability and protected VP1 from disassembly and protease degradation. The increase in VP1 expression levels caused by the presence of VP2 in cis was also observed in mammalian cells.

Xi Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Gastroenteritis,
    2016
    Co-Authors: Roberto Vidal, David O Matson, Xi Jiang, Nora Mamani, Veronica Solari, Jimena Vollaire, Patricia Roessler, Valeria Prado, Miguel L. O’ryan
    Abstract:

    Human Caliciviruses caused 45 % of 55 gastroenteriti

  • UPDATE ON Caliciviruses AND Human ACUTE
    2015
    Co-Authors: Et Al. Infect J Dis, Xi Jiang, Et Al. Med J Virol, Larry K Pickering
    Abstract:

    Caliciviruses (CVs) are single stranded, positive sense RNA vi-ruses closely related to picornavi-ruses. Four CV genera have been described, including Norwalk-like viruses (NLVs), Sapporo-like vi-ruses (SLVs), Vesivirus and Lagovi-rus.1 The former two genera mainly cause acute gastroenteritis in hu-mans and also are called Human Caliciviruses (HuCVs). The latter two genera mainly infect animals, causing a variety of manifestations, including mucosal infection, abor-tion and hemorrhage. Animal CVs that are related genetically to HuCVs and are associated with di-arrhea have been found in domestic animals. Evidence of transmission of these viruses to Humans is lack-ing. NLVs and SLVs recently have been renamed Norovirus and Sap-povirus, respectively, pending ap-proval by the International Com-mittee on Taxonomy of Viruses. Based on morphology, so-called typical and atypical CVs have been described. SLVs have the typical CV morphology, with a six pointed star appearance similar to those of many animal CVs. In contrast the surface structure of NLVs lacks a six pointed star appearance; it is smooth, leading to the designation “small round structured viruses.” Both NLV and SLV genera con-tain multiple members. Before the cloning of Norwalk virus in 1990,2 individual members were named after their location of discovery. For example, the prototype Nor-walk virus was identified in an out-break of acute gastroenteritis in an elementary school in Norwalk, OH, in 1968,3 and the prototyp

  • detection of norovirus sapovirus and rhesus enteric calicivirus specific antibodies in captive juvenile macaques
    Journal of General Virology, 2010
    Co-Authors: Tibor Farkas, Xi Jiang, Jason Dufour, Karol Sestak
    Abstract:

    The objective of this study was to determine the prevalence of anti-norovirus (NoV), -sapovirus (SaV) and -Tulane virus (TV) antibodies in rhesus macaques of the Tulane National Primate Research Center and to evaluate the antigenic relationship between these viruses. A high prevalence of NoV-binding (51–61 %) and SaV-binding (50–56 %) antibodies and TV-neutralizing (69 %) antibodies were detected. Serum samples obtained during a Human NoV outbreak and a multivalent anti-NoV hyperimmune serum were not able to neutralize TV infectivity. Conversely, low levels of cross-reactivity between the prototype TV and NoVs, but not between the TV and SaVs were detected by ELISA. These data indicate the preservation of some cross-reactive B-cell epitopes between the rhesus and Human Caliciviruses (CVs). The high prevalence of Human and rhesus CV-specific serum antibodies suggests the frequent exposure of colony macaques to enteric CVs including the possibility of CV transmission between Human and non-Human primate hosts.

  • Human Caliciviruses and pediatric gastroenteritis
    Seminars in Pediatric Infectious Diseases, 2004
    Co-Authors: Sarbelio Morenoespinosa, Tibor Farkas, Xi Jiang
    Abstract:

    Surveillance using molecular diagnostic methods developed in the past decade shows that Human Caliciviruses, particularly the Noroviruses, are the most important cause of pediatric acute gastroenteritis, next to rotavirus. Noroviruses also cause severe gastroenteritis in children, requiring hospitalization. The Sapovirus, a morphologically and genetically distinct genus of calicivirus, cause mainly milder endemic pediatric gastroenteritis. Noroviruses and Sapoviruses are genetically and antigenetically diverse, and multiple genetic types cocirculate in the same community. Human Caliciviruses still cannot be cultivated in cell culture or in an animal model. Significant progress has been made in the past decade in the classification, diagnosis, and vaccine development, as well as in the recent discovery of Norovirus recognizing Human histoblood group antigens as receptors. Major developments in this field are expected to occur in the near future.

  • molecular detection and sequence analysis of Human Caliciviruses from acute gastroenteritis outbreaks in hungary
    Journal of Medical Virology, 2002
    Co-Authors: Tibor Farkas, David O Matson, Tamas Berke, Gabor Reuter, Gyorgy Szucs, Xi Jiang
    Abstract:

    Three viral gastroenteritis (VGE) outbreaks that occurred in 1998–1999, in Hungary were investigated for the presence of Human Caliciviruses (HuCVs). HuCVs in stool specimens were detected by reverse transcription-polymerase chain reaction (RT-PCR) using primer pair 289/290, which was designed based on the RNA-dependent RNA polymerase (RdRp) sequence. RT-PCR results were confirmed by sequencing showing that all three outbreak strains belonged to genogroup II of “Norwalk-like viruses” (NLVs). Two strains had high sequence identity with strains in known genetic clusters (Hawaii and Lordsdale clusters). The third strain (MOH) had distinct RdRp sequence, sharing 77/86% (nt/aa) identity with Snow Mountain virus (SMV), the closest genogroup II virus. To characterize MOH further, we cloned, sequenced, and expressed in baculovirus its capsid gene. It had 75/79% (nt/aa) identity with SMV, but 97/98% (nt/aa) identity with NLV/Hillingdon/90/UK, a recently identified genetic cluster of HuCVs. The recombinant MOH (rMOH) capsid protein self-assembled into virus-like particles (VLPs), which is antigenically distinct from other recombinant HuCV capsid antigens available in our laboratory. Further study of this VLP will have important applications in antigenic characterization and diagnosis of HuCVs. J. Med. Virol. 67:567–573, 2002. © 2002 Wiley-Liss, Inc.

David O Matson - One of the best experts on this subject based on the ideXlab platform.

  • Gastroenteritis,
    2016
    Co-Authors: Roberto Vidal, David O Matson, Xi Jiang, Nora Mamani, Veronica Solari, Jimena Vollaire, Patricia Roessler, Valeria Prado, Miguel L. O’ryan
    Abstract:

    Human Caliciviruses caused 45 % of 55 gastroenteriti

  • Perspectives Calicivirus Emergence from Ocean Reservoirs: Zoonotic and Interspecies Movements
    2013
    Co-Authors: Alvin W. Smith, Douglas E. Skilling, Neil Cherry, Jay H. Mead, David O Matson
    Abstract:

    Caliciviral infections in Humans, among the most common causes of viral-induced vomiting and diarrhea, are caused by the Norwalk group of small round structured viruses, the Sapporo Caliciviruses, and the hepatitis E agent. Human Caliciviruses have been resistant to in vitro cultivation, and direct study of their origins and reservoirs outside infected Humans or water and foods (such as shellfish contaminated with Human sewage) has been difficult. Modes of transmission, other than direct fecal-oral routes, are not well understood. In contrast, animal viruses found in ocean reservoirs, which make up a second calicivirus group, can be cultivated in vitro. These viruses can emerge and infect terrestrial hosts, including Humans. This article reviews the history of animal Caliciviruses, their eventual recognition as zoonotic agents, and their potential usefulness as a predictive model for noncultivatable Human and other animal Caliciviruses (e.g., those seen in association with rabbit hemorrhagic disease). In vitro cultivation of Caliciviruses indicates that these pathogens have been emerging periodically from ocean sources for 65 years (1)

  • molecular detection and sequence analysis of Human Caliciviruses from acute gastroenteritis outbreaks in hungary
    Journal of Medical Virology, 2002
    Co-Authors: Tibor Farkas, David O Matson, Tamas Berke, Gabor Reuter, Gyorgy Szucs, Xi Jiang
    Abstract:

    Three viral gastroenteritis (VGE) outbreaks that occurred in 1998–1999, in Hungary were investigated for the presence of Human Caliciviruses (HuCVs). HuCVs in stool specimens were detected by reverse transcription-polymerase chain reaction (RT-PCR) using primer pair 289/290, which was designed based on the RNA-dependent RNA polymerase (RdRp) sequence. RT-PCR results were confirmed by sequencing showing that all three outbreak strains belonged to genogroup II of “Norwalk-like viruses” (NLVs). Two strains had high sequence identity with strains in known genetic clusters (Hawaii and Lordsdale clusters). The third strain (MOH) had distinct RdRp sequence, sharing 77/86% (nt/aa) identity with Snow Mountain virus (SMV), the closest genogroup II virus. To characterize MOH further, we cloned, sequenced, and expressed in baculovirus its capsid gene. It had 75/79% (nt/aa) identity with SMV, but 97/98% (nt/aa) identity with NLV/Hillingdon/90/UK, a recently identified genetic cluster of HuCVs. The recombinant MOH (rMOH) capsid protein self-assembled into virus-like particles (VLPs), which is antigenically distinct from other recombinant HuCV capsid antigens available in our laboratory. Further study of this VLP will have important applications in antigenic characterization and diagnosis of HuCVs. J. Med. Virol. 67:567–573, 2002. © 2002 Wiley-Liss, Inc.

  • sequence diversity of Human Caliciviruses recovered from children with diarrhea in mendoza argentina 1995 1998
    Journal of Medical Virology, 2002
    Co-Authors: Norma Martinez, Xi Jiang, W M Zhong, Carlos Espul, Hector Cuello, David O Matson
    Abstract:

    Human Caliciviruses were detected by EIA and/or RT-PCR in stool specimens from children with diarrhea treated at out- or in-patient facilities between 1995 and 1998 in Mendoza, Argentina. Mexico virus-like strains detected by primers NV36/51 were transiently prevalent in 1995/1996. Significantly more Human Caliciviruses were detected when primers were designed from contemporaneously circulating strains. Nucleotide sequences of a highly conserved region in the RNA polymerase gene of 10 selected Human Caliciviruses were determined. Eight strains were Norwalk-like viruses and two strains were Sapporo-like viruses. Seven of the eight Norwalk-like viruses also were positive by the recombinant Mexico virus antigen EIA. The seven Mexico virus EIA-positive strains revealed two patterns in the RNA polymerase sequences: two strains were closest to Mexico virus and the other five strains were closest to Lordsdale virus. One of the five "Lordsdale" viruses was found to be a naturally occurring recombinant between the Mexico virus and Lordsdale Human calicivirus genetic clusters [Jiang et al., (1999b) Archives of Virology 144:2377-2387]. The Mexico virus EIA-negative strain had 73-77% nucleotide identity with the closest related Norwalk-like viruses, indicating it might belong to a new genetic cluster of the Norwalk-like virus genus. The two Sapporo-like viruses were distinct genetically; one belonged to the Houston/90 or Parkville cluster and the other to a new cluster. Some strains appeared to have short periods of prevalence and locally adapted primer pairs significantly increased detection rates. The finding of high diversity of circulating strains, including recombinant strains and strains with previously unrecognized genetic identities, highlights a need for studies of Human Caliciviruses in these children and other populations.

  • Human Caliciviruses are a significant pathogen of acute sporadic diarrhea in children of santiago chile
    The Journal of Infectious Diseases, 2000
    Co-Authors: Miguel Oryan, Xi Jiang, Nora Mamani, Aldo Gaggero, Luis F Avendano, Susana Prieto, Alfredo Pena, David O Matson
    Abstract:

    Human Caliciviruses (HuCVs) are increasingly recognized as common pathogens that cause acute sporadic diarrhea in children; however, regional antigenic and genetic diversity complicate detection techniques. Stool samples from children seeking medical attention in 2 outpatient clinics, a large emergency department, and 2 hospital wards were evaluated for HuCVs by reverse transcription-polymerase chain reaction, using primers based on a conserved sequence of the polymerase region of a previously sequenced Chilean strain. HuCVs were detected in 53 (8%) of 684 children 1 month to 5 years of age (mean, 13 months). Detection occurred year-round without a clear seasonal peak, and detection frequency declined from 16% in 1997 to 2% in 1999. The decline may have been due to a change in virus genotype. HuCVs are a significant pathogen of acute sporadic diarrhea in Chilean children, and continuous characterization of genetic diversity will be crucial for appropriate detection.

Linda J Saif - One of the best experts on this subject based on the ideXlab platform.

  • identification of a porcine calicivirus related genetically to Human sapoviruses
    Journal of Clinical Microbiology, 2008
    Co-Authors: Vito Martella, Veronica Costantini, Eleonora Lorusso, Krisztian Banyai, Nicola Decaro, Marialaura Corrente, Gabriella Elia, Alessandra Cavalli, Arianna Radogna, Linda J Saif
    Abstract:

    Whether animals may act as reservoirs for Human Caliciviruses is unclear. By sequence analysis of a short fragment of the RNA-dependent RNA polymerase (RdRp) region, porcine sapovirus (SaV) strains that genetically resemble Human SaVs have been detected in piglets, but more-informative sequences (capsid gene) were not available for a precise characterization. In this study, the 3′ terminus (the 3′ end of open reading frame 1 [ORF1], including the polymerase complex and the complete capsid; ORF2; and the 3′ untranslated region) of one such Human SaV-like strain, 43/06-18p3/2006/It, was determined, revealing that these viruses are more related genetically to Human (47.4 to 54.9% amino acid identity) than to animal (35.2 to 44.7% amino acid identity) SaVs in the capsid gene. In addition, the recombination-prone RdRp-capsid junction region was highly conserved with those of Human SaVs of genogroup GI. The presence of porcine viruses similar to Human SaVs is a significant finding because of the potential for zoonotic infections or generation of porcine/Human recombinants.

  • porcine enteric Caliciviruses genetic and antigenic relatedness to Human Caliciviruses diagnosis and epidemiology
    Vaccine, 2007
    Co-Authors: Qiuhong Wang, Veronica Costantini, Linda J Saif
    Abstract:

    Porcine enteric Caliciviruses include sapoviruses and noroviruses. Porcine sapoviruses infect pigs of all ages and cause diarrhea in young pigs, whereas porcine noroviruses were detected exclusively from adult pigs without clinical signs. Importantly, certain porcine norovirus strains were genetically and antigenically related to Human noroviruses. This raises public health concerns that pigs may be reservoirs for emergence of epidemic Human norovirus strains. This article reviews the discovery of porcine noroviruses and sapoviruses, their classification, diagnosis, epidemiology and genetic and antigenic relatedness to Human Caliciviruses.

  • Human and animal enteric Caliciviruses in oysters from different coastal regions of the united states
    Applied and Environmental Microbiology, 2006
    Co-Authors: Veronica Costantini, Francoise Le S Guyader, Fabienne Loisy, Lynn A Joens, Linda J Saif
    Abstract:

    Food-borne diseases are a major cause of morbidity and hospitalization worldwide. Enteric Caliciviruses are capable of persisting in the environment and in the tissues of shellfish. Human noroviruses (HuNoVs) have been implicated in outbreaks linked to shellfish consumption. The genetic and antigenic relatedness between Human and animal enteric Caliciviruses suggests that interspecies transmission may occur. To determine the occurrence of Human and animal enteric Caliciviruses in United States market oysters, we surveyed regional markets. Oysters were collected from 45 bays along the United States coast during the summer and winter of 2002 and 2003. Samples were analyzed by reverse transcription-PCR, and results were confirmed by hybridization and sequence analysis. Nine samples (20%) were positive for HuNoV genogroup II after hybridization. Animal enteric Caliciviruses were detected in 10 samples (22%). Seven of these samples were positive for porcine norovirus genogroup II, and one sample was positive for porcine sapovirus after hybridization and confirmation by sequencing. Bovine noroviruses were detected in two samples, and these results were confirmed by sequencing. Five HuNoV samples sequenced in the polymerase region were similar to the norovirus genogroup II US 95/96 subset (genogroup II-4) previously implicated in diarrhea outbreaks. Different seasonal and state distributions were detected. The presence of animal enteric Caliciviruses was associated with states with high livestock production. Although the presence of Human Caliciviruses in raw oysters represents a potential risk for gastroenteritis, disease confirmation by investigation of outbreaks is required. The simultaneous detection of Human and animal enteric Caliciviruses raises concerns about Human infection or coinfection with Human and animal strains that could result in genomic recombination and the emergence of new strains.

  • reverse transcription pcr assays for detection of bovine enteric Caliciviruses bec and analysis of the genetic relationships among bec and Human Caliciviruses
    Journal of Clinical Microbiology, 2003
    Co-Authors: Jeffrey R Smiley, Armando E Hoet, M Traven, Hiroshi Tsunemitsu, Linda J Saif
    Abstract:

    Two genetically distinct bovine enteric Caliciviruses (BECs) have been identified: the norovirus (NLV) Jena and Newbury Agent-2 (NA-2) BECs, which are genetically related to Human noroviruses, and the Nebraska (NB) BECs, which is related to sapoviruses and lagoviruses but may also represent a new calicivirus genus. The prevalence of these two BEC genotypes in cattle is unknown. Although reverse transcription-PCR (RT-PCR) primers for Human NLV recognize NLV-BECs, the genetic relationships between NLV from Humans and the NLV-BECs commonly circulating in cattle is undefined. In the present study, veal calf fecal samples were assayed for enteric Caliciviruses by using six RT-PCR primer sets designed for the detection of Human NLVs or BECs. Caliciviruses genetically related to the NLV-BEC Jena and NA-2 strains or to the recently characterized NB BEC strain were identified in three of four and four of four sampled veal herds, respectively. Extended 3'-terminal genome sequences of two NLV-BECs, designated CV95-OH and CV186-OH, encoding the RNA-dependent RNA polymerase (RdRp; open reading frame 1 [ORF-1]), VP1 (ORF-2), and VP2 (ORF-3) genes were determined. Phylogenetic and sequence identity analyses of each genome region demonstrated these viruses to be most closely related to the NLV-BEC Jena and NA-2 strains. In initial testing, the Human P289-P290 (P289/290) primer set was found to be the most sensitive for calicivirus detection. However, its failure to identify all positive fecal pools (as determined by other assays) led us to design two new primer sets, CBECU-F/R and NBU-F/R, for the sensitive and specific detection of NLV-BEC (NLV-BEC Jena and NA-2) and BEC-NB-like viruses, respectively. The RT-PCR assays with the new primers were compared against other primer sets, including P289/290. Composite results of the tests completed by using the new assays identified 72% (54 of 75) of veal calf fecal samples as positive, with 21 of 21 sequenced reaction products specific for the target RdRp gene. The same design strategy used for the new BEC assays may also be applicable to the design of similar assays for the detection of Human Caliciviruses (HuCVs). Our data support the genetic relationship between NLV-BECs and NLV-HuCVs but with the NLV-BECs comprising two clusters within a third NLV genogroup.

  • molecular characterization of a porcine enteric calicivirus genetically related to sapporo like Human Caliciviruses
    Journal of Virology, 1999
    Co-Authors: M Guo, Michele E Hardy, Kyeongok Chang, Qijing Zhang, Anil V Parwani, Linda J Saif
    Abstract:

    Porcine enteric calicivirus (PEC) is associated with diarrhea in pigs, and to date it is the only cultivable enteric calicivirus (tissue culture-adapted [TC] PEC/Cowden). Based on sequence analysis of cDNA clones and reverse transcription-PCR products, TC PEC/Cowden has an RNA genome of 7,320 bp, excluding its 3′ poly(A) + tail. The genome is organized in two open reading frames (ORFs), similar to the organizations of the Human Sapporo-like viruses (SLVs) and the lagoviruses. ORF1 encodes the polyprotein that is fused to and contiguous with the capsid protein. ORF2 at the 3′ end encodes a small basic protein of 164 amino acids. Among Caliciviruses, PEC has the highest amino acid sequence identities in the putative RNA polymerase (66%), 2C helicase (49.6%), 3C-like protease (43.7%), and capsid (39%) regions with the SLVs, indicating that PEC is genetically most closely related to the SLVs. The complete RNA genome of wild-type (WT) PEC/Cowden was also sequenced. Sequence comparisons revealed that the WT and TC PEC/Cowden have 100% nucleotide sequence identities in the 5′ terminus, 2C helicase, ORF2, and the 3′ nontranslated region. TC PEC/Cowden has one silent mutation in its protease, two amino acid changes and a silent mutation in its RNA polymerase, and five nucleotide substitutions in its capsid that result in one distant and three clustered amino acid changes and a silent mutation. These substitutions may be associated with adaptation of TC PEC/Cowden to cell culture. The cultivable PEC should be a useful model for studies of the pathogenesis, replication, and possible rescue of uncultivable Human enteric Caliciviruses.

Evelyne Kohli - One of the best experts on this subject based on the ideXlab platform.

  • Detection and characterization of Human Caliciviruses associated with sporadic acute diarrhea in adults in Djibouti (horn of Africa).
    American Journal of Tropical Medicine and Hygiene, 2008
    Co-Authors: Jérôme Maslin, Pierre Pothier, Elisabeth Nicand, Katia Ambert-balay, Christine Fouet, Jérôme Kaplon, Rachel Haus, Evelyne Kohli
    Abstract:

    Recent advances in molecular diagnostics have allowed us to recognize Human Caliciviruses (HuCVs) as important agents of acute diarrhea in industrialized countries. Their prevalence and genetic diversity in developing countries remains unknown. We report on the characterization of HuCVs among adults presenting acute diarrheas in Djibouti; 108 stool samples collected were screened by EIA, RTPCR, or cell cultures for the group A Rotaviruses, Adenoviruses, Astroviruses, and HuCVs, which were further characterized by genotyping. Among stool samples screened for HuCVs, 25.3% were positive. The other enteric viruses were less prevalent. The 11 HuCV strains sequenced revealed a large diversity (3 sapoviruses and 8 noroviruses). GII strains noroviruses were predominant, five were newly described genotypes, and two were recombinant with a pol gene related to GGIIb strains with the particularity to associate a unique pol gene to different capsid genes. These results could help to the knowledge of HuCV infections in Tropical Africa.

  • virus diversity in a winter epidemic of acute diarrhea in france
    Journal of Clinical Microbiology, 2002
    Co-Authors: Roxane Chikhibrachet, Fabienne Bon, Laurent Toubiana, Pierre Pothier, Jeanclaude Nicolas, Antoine Flahault, Evelyne Kohli
    Abstract:

    In France, an epidemic peak of acute diarrhea is observed each winter. Previous results suggested a viral etiology for these winter epidemics. We investigated the role of enteric viruses in acute diarrhea and their molecular diversity. One hundred sixty-one patients with acute diarrhea and 45 healthy patients (controls) from the general population were given a standardized questionnaire between December 1998 and May 1999. Stool specimens were screened for group A and C rotaviruses, Human Caliciviruses, astroviruses, and adenovirus types 40 and 41 by reverse transcription-PCR and/or enzyme immunoassay. Virologic analysis was positive for 63 cases (39%). Caliciviruses and group A rotaviruses were the most frequent (19 and 17% of cases, respectively). Two control stool specimens were found positive for group A rotavirus, and one was found positive for astrovirus. Molecular characterization of the strains disclosed a cocirculation of P[8],G1, P[8],G4, and P[4],G2 rotaviruses; type 1, 2, 3, 4, and 8 astroviruses; and Sapporo-like and Norwalk-like Human Caliciviruses. These four types of viruses accounted for an attributable risk of acute diarrhea of 34.7% for the general population, under the assumption of a causal role of these viruses.

  • prevalence of group a rotavirus Human calicivirus astrovirus and adenovirus type 40 and 41 infections among children with acute gastroenteritis in dijon france
    Journal of Clinical Microbiology, 1999
    Co-Authors: Fabienne Bon, Pierre Pothier, P Fascia, M Dauvergne, D Tenenbaum, H Planson, A M Petion, Evelyne Kohli
    Abstract:

    Group A rotaviruses, Human Caliciviruses, astroviruses, and adenovirus types 40 and 41 were detected by enzyme immunoassay or reverse transcription-PCR in 61, 14, 6, and 3% of stool specimens from 414 children consulting for gastroenteritis between 1995 and 1998. These data highlight the importance of Caliciviruses in infantile gastroenteritis. Among these, Norwalk-like viruses belonging to genogroup II were predominant.