Glyn Stanway

Classification of enteroviruses based on molecular and biological properties.

IP: 54.70.40.11 On: Sat, 08 Dec 2018 03:07:20 Journal of General Virology (1997), 78, 1–11. Printed in Great Britain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Human parechoviruses—biology and clinical significance

A new genus of the family Picornaviridae, Parechovirus, has recently been recognised on the basis of distinctive biological and molecular properties. In particular: parechoviruses exhibit characteristic effects on the host cell; cleavage of the capsid protein VP0, required for maturation of the virus particle in most other picornaviruses, does not occur; there is a unique extension, which is highly basic in character, to the N‐terminus of the capsid protein VP3; and the 2A protein, in common with those of only two other known picornaviruses, is a homologue of a family of cellular proteins involved in the control of cell proliferation. The type member of the Parechovirus genus is a frequent human pathogen, formerly known as echovirus 22, which has been renamed human parechovirus 1. The genus also includes the closely related virus, human parechovirus 2 (formerly echovirus 23). Human parechoviruses generally cause mild, gastrointestinal or respiratory illness, but more serious consequences of infection, such as myocarditis and encephalitis have been reported. Most infections occur in young children. Ljungan virus, a newly identified virus of rodents, shares a number of molecular features with the human parechoviruses, raising important questions about the evolution of parechoviruses and their introduction into the human population. Copyright

Structure, function and evolution of picornaviruses

Conclusion This review illustrates how molecular and structural analyses have contributed to a greater understanding of the rich biological diversity seen in the picornaviruses. In many cases the second phase of studies, based on increasingly powerful genetic engineering, biochemical and immunological techniques is now well under way and beginning to reveal the depth of the vast store of information which still lies encoded cryptically in the sequences and structures which have been determined. The advances made already suggest that the next few years will be even more fruitful than those since 1981 when the first picornavirus sequence was published.

Analysis of a New Human Parechovirus Allows the Definition of Parechovirus Types and the Identification of RNA Structural Domains

ABSTRACT Human parechoviruses (HPeV), members of the Parechovirus genus of Picornaviridae, are frequent pathogens but have been comparatively poorly studied, and little is known of their diversity, evolution, and molecular biology. To increase the amount of information available, we have analyzed 7 HPeV strains isolated in California between 1973 and 1992. We found that, on the basis of VP1 sequences, these fall into two genetic groups, one of which has not been previously observed, bringing the number of known groups to five. While these correlate partly with the three known serotypes, two members of the HPeV2 serotype belong to different genetic groups. In view of the growing importance of molecular techniques in diagnosis, we suggest that genotype is an important criterion for identifying viruses, and we propose that the genetic groups we have defined should be termed human parechovirus types 1 to 5. Complete nucleotide sequence analysis of two of the Californian isolates, representing two types, confirmed the identification of a new genetic group and suggested a role for recombination in parechovirus evolution. It also allowed the identification of a putative HPeV1 cis-acting replication element, which is located in the VP0 coding region, as well as the refinement of previously predicted 5′ and 3′ untranslated region structures. Thus, the results have significantly improved our understanding of these common pathogens.

Integrin αvβ6 Is an RGD-Dependent Receptor for Coxsackievirus A9

ABSTRACT Coxsackievirus A9 (CAV9), a member of the Enterovirus genus of Picornaviridae, is a common human pathogen and is one of a significant number of viruses containing a functional arginine-glycine-aspartic acid (RGD) motif in one of their capsid proteins. Previous studies identified the RGD-recognizing integrin αvβ3 as its cellular receptor. However, integrin αvβ6 has been shown to be an efficient receptor for another RGD-containing picornavirus, foot-and-mouth disease virus (FMDV). In view of the similarity in sequence context of the RGD motifs in CAV9 and FMDV, we investigated whether αvβ6 can also serve as a receptor for CAV9. We found that CAV9 can bind to purified αvβ6 and also to SW480 cells transfected with β6 cDNA, allowing expression of αvβ6 on their surface, but it cannot bind to mock-transfected cells. In addition, a higher yield of CAV9 was obtained in β6-expressing cells than in mock-transfected cells. There was no similar enhancement in infection with an RGD-less CAV9 mutant. We also found β6 on the surface of GMK cells, a cell line which CAV9 infects efficiently by an RGD-dependent mechanism. Significantly, this infection is blocked by an antibody to αvβ6, while this antibody did not block the low level of infection by the RGD-less mutant. Thus, integrin αvβ6 is an RGD-dependent receptor for CAV9 and may be important in natural CAV9 infections.

The crystal structure of coxsackievirus A9: new insights into the uncoating mechanisms of enteroviruses

BACKGROUND Coxsackievirus A9 (CAV9), a human pathogen causing symptoms ranging from common colds to fatal infections of the central nervous system, is an icosahedral single-stranded RNA virus that belongs to the genus Enterovirus of the family Picornaviridae. One of the four capsid proteins, VP1, includes the arginine-glycine-aspartate (RGD) motif within its C-terminal extension. This region binds to integrin alpha v beta 3, the only receptor for CAV9 to be conclusively identified to date. RESULTS The crystal structure of CAV9 in complex with the antiviral compound WIN 51711 has been solved to 2.9 A resolution. The structures of the four capsid proteins, VP1 to VP4, resemble those of other picornaviruses. The antiviral compound is bound in the VP1 hydrophobic pocket, and it is possible that the pocket entrance contains a second WIN 51711 molecule. Continuous electron density for the VP1 N terminus provides a complete picture of the structure close to the fivefold axis. The VP1 C-terminal portion is on the outer surface of the virus and becomes disordered five-residues N-terminal to the RGD motif. CONCLUSIONS The RGD motif is exposed and flexible in common with other known integrin ligands. Although CAV9 resembles coxsackie B viruses (CBVs), several substitutions in the areas implicated in CBV receptor attachment suggest it may recognise a different receptor. The structure along the fivefold axis provides new information on the uncoating mechanism of enteroviruses. CAV9 might bind a larger natural pocket factor than other picornaviruses, an observation of particular relevance to the design of new antiviral compounds.

Virus Antibody Survey in Different European Populations Indicates Risk Association Between Coxsackievirus B1 and Type 1 Diabetes

Enteroviruses (EVs) have been connected to type 1 diabetes in various studies. The current study evaluates the association between specific EV subtypes and type 1 diabetes by measuring type-specific antibodies against the group B coxsackieviruses (CVBs), which have been linked to diabetes in previous surveys. Altogether, 249 children with newly diagnosed type 1 diabetes and 249 control children matched according to sampling time, sex, age, and country were recruited in Finland, Sweden, England, France, and Greece between 2001 and 2005 (mean age 9 years; 55% male). Antibodies against CVB1 were more frequent among diabetic children than among control children (odds ratio 1.7 [95% CI 1.0–2.9]), whereas other CVB types did not differ between the groups. CVB1-associated risk was not related to HLA genotype, age, or sex. Finnish children had a lower frequency of CVB antibodies than children in other countries. The results support previous studies that suggested an association between CVBs and type 1 diabetes, highlighting the possible role of CVB1 as a diabetogenic virus type.

Arginine-Glycine-Aspartic Acid Motif Is Critical for Human Parechovirus 1 Entry

ABSTRACT The human parechovirus 1 RGD motif in VP1 was studied by mutagenesis. An RGD-to-RGE change gave only revertant viruses with a restored RGD, while deletion of GD was lethal and nonrevertable. Mutations at the +1 and +2 positions had some effect on growth properties and a +1 M-to-P change was lethal. These studies indicate that the RGD motif plays a critical role in infectivity, presumably by interacting with integrins, and that downstream amino acids can have an influence on function.

The nucleotide sequences of wild-type coxsackievirus A9 strains imply that an RGD motif in VP1 is functionally significant

We have shown previously that, compared to other enteroviruses, the coxsackievirus A9 (CAV-9) prototype strain, Griggs, contains a C-terminal extension to the capsid protein VP1 and that within this extension there is an RGD (arginine-glycine-aspartic acid) motif. To determine whether these features are found in other CAV-9 strains and therefore analyse whether they are likely to be functionally important, we have determined the nucleotide sequence of the appropriate region from five strains, isolated over a 25 year period. The results indicate that there is considerable diversity between the strains and there is little correlation between nucleotide sequence identity and date of isolation. All isolates exhibit the VP1 extension and although its amino acid sequence is otherwise variable, the RGD motif is common to all. This conservation of sequence, within a region which can otherwise vary, implies that the RGD sequence must be functionally significant. The VP1 extension shows similarity to sequences found in foot-and-mouth-disease virus strains and to part of the precursor of the cellular protein, human transforming growth factor beta, and the possible significance of these observations is discussed.

Comprehensive full-length sequence analyses of human parechoviruses: diversity and recombination

Human parechoviruses (HPeVs) are highly prevalent pathogens among very young children. Although originally classified into two serologically distinct types, HPeV1 and -2, recent analyses of variants collected worldwide have revealed the existence of 12 further types classified genetically by sequence comparisons of complete genome sequences or the capsid (VP1) gene. To investigate the nature of HPeV evolution, its population dynamics and recombination breakpoints, this study generated 18 full-length genomic sequences of the most commonly circulating genotypes, HPeV1 and -3, collected over a time span of 14 years from The Netherlands. By inclusion of previously published full-length sequences, 35 sequences were analysed in total. Analysis of contemporary strains of HPeV1 and those most similar to the prototype strain (Harris) showed that HPeV1 variants fall into two genetically distinct clusters that are much more divergent from each other than those observed within other HPeV types. Future classification criteria for HPeVs may require modification to accommodate the occurrence of variants with intermediate degrees of diversity within types. Recombination was frequently observed among HPeV1, -4, -5 and -6, but was much more restricted among HPeV3 strains. Favoured sites for recombination were found to flank the capsid region, and further sites were found within the non-structural region, P2. In contrast to other HPeV types, the majority of the HPeV3 sequences remained monophyletic across the genome, a possible reflection of its lower diversity and potentially more recent emergence than other HPeV types, or biological and/or epidemiological constraints that limit opportunities for co-infections with potential recombination partners.