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The Journal of General Virology Oct 2019Noroviruses are genetically diverse RNA viruses associated with acute gastroenteritis in mammalian hosts. Phylogenetically, they can be segregated into different...
Noroviruses are genetically diverse RNA viruses associated with acute gastroenteritis in mammalian hosts. Phylogenetically, they can be segregated into different genogroups as well as P (polymerase)-groups and further into genotypes and P-types based on amino acid diversity of the complete VP1 gene and nucleotide diversity of the RNA-dependent RNA polymerase (RdRp) region of ORF1, respectively. In recent years, several new noroviruses have been reported that warrant an update of the existing classification scheme. Using previously described 2× standard deviation (sd) criteria to group sequences into separate clusters, we expanded the number of genogroups to 10 (GI-GX) and the number of genotypes to 48 (9 GI, 27 GII, 3 GIII, 2 GIV, 2 GV, 2 GVI and 1 genotype each for GVII, GVIII, GIX [formerly GII.15] and GX). Viruses for which currently only one sequence is available in public databases were classified into tentative new genogroups (GNA1 and GNA2) and genotypes (GII.NA1, GII.NA2 and GIV.NA1) with their definitive assignment awaiting additional related sequences. Based on nucleotide diversity in the RdRp region, noroviruses can be divided into 60 P-types (14 GI, 37 GII, 2 GIII, 1 GIV, 2 GV, 2 GVI, 1 GVII and 1 GX), 2 tentative P-groups and 14 tentative P-types. Future classification and nomenclature updates will be based on complete genome sequences and will be coordinated and disseminated by the international norovirus classification-working group.
Topics: Caliciviridae Infections; Gastroenteritis; Genome, Viral; Genotype; Humans; Norovirus; Phylogeny
PubMed: 31483239
DOI: 10.1099/jgv.0.001318 -
Gut Microbes 2021Human noroviruses are the most common viral cause of acute gastroenteritis worldwide. Currently, there are no approved vaccines or specific therapeutics to treat the... (Review)
Review
Human noroviruses are the most common viral cause of acute gastroenteritis worldwide. Currently, there are no approved vaccines or specific therapeutics to treat the disease. Some obstacles delaying the development of a norovirus vaccine are: (i) the extreme diversity presented by noroviruses; (ii) our incomplete understanding of immunity to noroviruses; and (iii) the lack of a robust cell culture system or animal model for human noroviruses. Recent advances in cultivation of norovirus, novel approaches applied to viral genomics and immunity, and completion of vaccine trials and birth cohort studies have provided new information toward a better understanding of norovirus immunity. Here, we will discuss the complex relationship between norovirus diversity and correlates of protection for human noroviruses, and how this information could be used to guide the development of cross-protective vaccines.
Topics: Animals; Biodiversity; Birth Cohort; Caliciviridae Infections; Genetic Predisposition to Disease; Host Microbial Interactions; Humans; Immunity; Norovirus; Vaccines
PubMed: 33783322
DOI: 10.1080/19490976.2021.1900994 -
Viruses Mar 2019Besides noroviruses, the family comprises four other accepted genera: , and . There are six new genera proposed: , and All have closely related genome structures, but... (Review)
Review
Besides noroviruses, the family comprises four other accepted genera: , and . There are six new genera proposed: , and All have closely related genome structures, but are genetically and antigenically highly diverse and infect a wide range of mammalian host species including humans. Recombination in nature is not infrequent for most of the , contributing to their diversity. Sapovirus infections cause diarrhoea in pigs, humans and other mammalian hosts. Lagovirus infections cause systemic haemorrhagic disease in rabbits and hares, and vesivirus infections lead to lung disease in cats, vesicular disease in swine, and exanthema and diseases of the reproductive system in large sea mammals. Neboviruses are an enteric pathogen of cattle, differing from bovine norovirus. At present, only a few selected caliciviruses can be propagated in cell culture (permanent cell lines or enteroids), and for most of the cultivatable caliciviruses helper virus-free, plasmid only-based reverse genetics systems have been established. The replication cycles of the caliciviruses are similar as far as they have been explored: viruses interact with a multitude of cell surface attachment factors (glycans) and co-receptors (proteins) for adsorption and penetration, use cellular membranes for the formation of replication complexes and have developed mechanisms to circumvent innate immune responses. Vaccines have been developed against lagoviruses and vesiviruses, and are under development against human noroviruses.
Topics: Animals; Caliciviridae; Caliciviridae Infections; Genome, Viral; Humans; Norovirus; Phylogeny; Sequence Analysis, DNA
PubMed: 30901945
DOI: 10.3390/v11030286 -
Viruses Aug 2021Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the , , and... (Review)
Review
Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the , , and virus families. This modification occurs when the RNA-dependent RNA polymerase (RdRp) attaches one or more nucleotides to a target protein through a nucleotidyl-transferase reaction. The most characterized nucleotidylylation target is VPg (viral protein genome-linked), a protein linked to the 5' end of the genome in , and . The nucleotidylylation of VPg by RdRp is a critical step for the VPg protein to act as a primer for genome replication and, in and for the initiation of translation. In contrast, do not express a VPg protein, but the nucleotidylylation of proteins involved in replication initiation is critical for genome replication. Furthermore, the RdRp proteins of the viruses that perform nucleotidylylation are themselves nucleotidylylated, and in the case of coronavirus, this has been shown to be essential for viral replication. This review focuses on nucleotidylylation within the picornavirus supergroup of viruses, including the proteins that are modified, what is known about the nucleotidylylation process and the roles that these modifications have in the viral life cycle.
Topics: Caliciviridae; Coronaviridae; Genome, Viral; Nidovirales; Nucleotides; Picornaviridae; Positive-Strand RNA Viruses; Potyviridae; RNA, Viral; RNA-Dependent RNA Polymerase; Viral Proteins; Virus Replication
PubMed: 34452414
DOI: 10.3390/v13081549 -
Uirusu Dec 2011Caliciviruses represented by norovirus and sapovirus exist not only in human but also in other animal species. Clinical manifestations are gastroenteritis, respiratory... (Review)
Review
Caliciviruses represented by norovirus and sapovirus exist not only in human but also in other animal species. Clinical manifestations are gastroenteritis, respiratory infections, vesicles and hemorrhagic skin diseases and others symptoms depended on the viruses. Inapparent symptom of calicivirus infection is also recognized. Calicivirus is stable in the environment and found sometimes in contaminated food or water sources. In addition to intragenomic mutation, intragenomic recombination is the common phenomenon that usually found in calicivirus genome. The genomic recombinations have been reported among the strains within the same animal species. For diagnosis and molecular epidemiological study, several laboratory methods are available, such as genetic molecular analysis, enzyme immunoassay and immunochromatography, which developed by using the antibody against virus-like particles. The reactivity between virus and host immunity is type specific and the titer of cross reaction is not so high. There are evidences that the new variant strains are emerged and spread quickly year by year. Histo-blood group antigen (HBGA) is one of the specific host cells receptor for calicivirus. Infectivity of the virus depends on specificity of the HBGA on the host cells. Because of the inability to culture human norovirus and sapovirus, pathogenesis and immunological data are limited. So far, only feline calicivirus and mouse norovirus are cultivable. Animal model studies for calicivirus by gnotobiotic pigs with human calicivirus and mouse with mouse norovirus are mainly used for experiments of pathobiological study, treatment and vaccine development.
Topics: Animals; Caliciviridae; Caliciviridae Infections; Gastroenteritis; Humans; Mice; Norovirus; Sapovirus; Viral Vaccines
PubMed: 22916566
DOI: 10.2222/jsv.61.193 -
Frontiers in Immunology 2019Noroviruses and Sapoviruses, classified in the family, are small positive-stranded RNA viruses, considered nowadays the leading cause of acute gastroenteritis globally... (Review)
Review
Noroviruses and Sapoviruses, classified in the family, are small positive-stranded RNA viruses, considered nowadays the leading cause of acute gastroenteritis globally in both children and adults. Although most noroviruses have been associated with gastrointestinal disease in humans, almost 50 years after its discovery, there is still a lack of comprehensive evidence regarding its biology and pathogenesis mainly because they can be neither conveniently grown in cultured cells nor propagated in animal models. However, other members of this family such as Feline calicivirus (FCV), Murine norovirus (MNV), Rabbit hemorrhagic disease virus (RHDV), and Porcine sapovirus (PS), from which there are accessible propagation systems, have been useful to study the calicivirus replication strategies. Using cell cultures and animal models, many of the functions of the viral proteins in the viral replication cycles have been well-characterized. Moreover, evidence of the role of viral proteins from different members of the family in the establishment of infection has been generated and the mechanism of their immunopathogenesis begins to be understood. In this review, we discuss different aspects of how caliciviruses are implicated in membrane rearrangements, apoptosis, and evasion of the immune responses, highlighting some of the pathogenic mechanisms triggered by different members of the family.
Topics: Adaptive Immunity; Animals; Antimicrobial Cationic Peptides; Apoptosis; Caliciviridae; Caliciviridae Infections; Cell Membrane; Cytopathogenic Effect, Viral; Disease Susceptibility; Gene Expression Regulation, Viral; Genome, Viral; Host-Pathogen Interactions; Humans; Immune Evasion; Immunity; Immunity, Innate; Immunomodulation; Microbial Interactions; Microbiota; Virus Replication
PubMed: 31632406
DOI: 10.3389/fimmu.2019.02334 -
Cell Host & Microbe Jun 2014Human noroviruses are a major cause of epidemic and sporadic gastroenteritis worldwide and can chronically infect immunocompromised patients. Efforts to develop... (Review)
Review
Human noroviruses are a major cause of epidemic and sporadic gastroenteritis worldwide and can chronically infect immunocompromised patients. Efforts to develop effective vaccines and antivirals have been hindered by the uncultivable nature and extreme genetic diversity of human noroviruses. Although they remain a particularly challenging pathogen to study, recent advances in norovirus animal models and in vitro cultivation systems have led to an increased understanding of norovirus molecular biology and replication, pathogenesis, cell tropism, and innate and adaptive immunity. Furthermore, clinical trials of vaccines consisting of nonreplicating virus-like particles have shown promise. In this review, we summarize these recent advances and discuss controversies in the field, which is rapidly progressing toward generation of antiviral agents and increasingly effective vaccines.
Topics: Antiviral Agents; Caliciviridae Infections; Gastroenteritis; Host-Pathogen Interactions; Humans; Immunity, Humoral; Norovirus; Viral Vaccines
PubMed: 24922570
DOI: 10.1016/j.chom.2014.05.015 -
Clinical Microbiology and Infection :... Aug 2014Norovirus (NoV) is now the dominant aetiological agent of acute gastroenteritis, and, with the recent introduction of rotavirus vaccines in many countries, this is... (Review)
Review
Norovirus (NoV) is now the dominant aetiological agent of acute gastroenteritis, and, with the recent introduction of rotavirus vaccines in many countries, this is likely to remain the case. NoV has a significant impact on human wellbeing in terms of morbidity, economic costs and mortality in developing countries. NoVs are divided into six genogroups (GI-GVI), but only GI, GII and GIV are known to infect humans, with GII being the most prevalent, causing >95% of human infections. The immune system is thought to drive selection of emerging pandemic NoVs through both antigenic drift and shift. This phenomenon results in the replacement of dominant circulating viruses approximately every 3 years, with new variants able to re-infect hosts previously infected with earlier viruses. This review explores the evolutionary aspects of contemporary NoVs.
Topics: Caliciviridae Infections; Evolution, Molecular; Gastroenteritis; Genetic Drift; Genetic Variation; Genotype; Humans; Norovirus; Selection, Genetic
PubMed: 24980204
DOI: 10.1111/1469-0691.12746 -
Clinical Microbiology Reviews Jan 2015Sapoviruses cause acute gastroenteritis in humans and animals. They belong to the genus Sapovirus within the family Caliciviridae. They infect and cause disease in... (Review)
Review
Sapoviruses cause acute gastroenteritis in humans and animals. They belong to the genus Sapovirus within the family Caliciviridae. They infect and cause disease in humans of all ages, in both sporadic cases and outbreaks. The clinical symptoms of sapovirus gastroenteritis are indistinguishable from those caused by noroviruses, so laboratory diagnosis is essential to identify the pathogen. Sapoviruses are highly diverse genetically and antigenically. Currently, reverse transcription-PCR (RT-PCR) assays are widely used for sapovirus detection from clinical specimens due to their high sensitivity and broad reactivity as well as the lack of sensitive assays for antigen detection or cell culture systems for the detection of infectious viruses. Sapoviruses were first discovered in 1976 by electron microscopy in diarrheic samples of humans. To date, sapoviruses have also been detected from several animals: pigs, mink, dogs, sea lions, and bats. In this review, we focus on genomic and antigenic features, molecular typing/classification, detection methods, and clinical and epidemiological profiles of human sapoviruses.
Topics: Animals; Antigens, Viral; Caliciviridae Infections; Genome, Viral; Humans; Molecular Typing; Sapovirus
PubMed: 25567221
DOI: 10.1128/CMR.00011-14 -
Viruses Jun 2020Protein-shelled viruses have been thought as "tin cans" that merely carry the genomic cargo from cell to cell. However, through the years, it has become clear that... (Review)
Review
Protein-shelled viruses have been thought as "tin cans" that merely carry the genomic cargo from cell to cell. However, through the years, it has become clear that viruses such as rhinoviruses and caliciviruses are active and dynamic structures waiting for the right environmental cues to deliver their genomic payload to the host cell. In the case of human rhinoviruses, the capsid has empty cavities that decrease the energy required to cause conformational changes, resulting in the capsids "breathing", waiting for the moment when the receptor binds for it to release its genome. Most strikingly, the buried N-termini of VP1 and VP4 are transiently exposed during this process. A more recent example of a "living" protein capsid is mouse norovirus (MNV). This family of viruses have a large protruding (P) domain that is loosely attached to the shell via a single-polypeptide tether. Small molecules found in the gut, such as bile salts, cause the P domains to rotate and collapse onto the shell surface. Concomitantly, bile alters the conformation of the P domain itself from one that binds antibodies to one that recognizes receptors. In this way, MNV appears to use capsid flexibility to present one face to the immune system and a completely different one to attack the host tissue. Therefore, it appears that even protein-shelled viruses have developed an impressive array of tricks to dodge our immune system and efficiently attack the host.
Topics: Animals; Caliciviridae; Caliciviridae Infections; Capsid; Humans; Picornaviridae Infections; Rhinovirus; Viral Proteins
PubMed: 32516952
DOI: 10.3390/v12060618