The novel hemagglutinin-esterase genes of human torovirus and Breda virus

Duckmanton, Lynn; Tellier, Raymond; Richardson, Chris; Petric, Martin

doi:10.1016/s0168-1702(99)00088-x

Cited by 14 publications

(15 citation statements)

References 25 publications

(56 reference statements)

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“…The torovirus nucleocapsid protein is the most abundant protein in the virions, and is highly antigenic as shown by the strong antibody response developed against it in gnobiotic calves experimentally infected with BToV. The N and HE proteins from BToV strain BRV-1 were expressed previously in E. coli and in insect cells (Duckmanton et al, 1999), respectively, and both proteins showed immunoreactivity to specific antisera and field serum samples by Western blot. However, these proteins were not used to develop any diagnostic assay.…”

Section: Discussionmentioning

confidence: 99%

Molecular characterization of a new PToV strain. Evolutionary implications

et al. 2009

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Toroviruses are emergent viruses, belonging to the Nidovirales order, that remain mostly ignored, despite they are able to infect different species of domestic animals and humans, causing enteric diseases and diarrhea. Thus far, only five variants of porcine torovirus (PToV) have been identified. In this report we describe the identification and partial characterization of a new strain of porcine torovirus (PToV-BRES) that was detected by RT-PCR in a swine faecal specimen from a farm in Brescia (Italy). The complete genes coding for the nucleocapsid (N), hemagglutinin-esterase (HE) and membrane (M) proteins were amplified, and sequence analysis showed that PToV-BRES is a new PToV strain that, based on the HE gene sequence, is phylogenetically related to P4 strain, that was up to now the only member of a distinct PToV lineage. The nucleocapsid protein from PToV-BRES was expressed in insect cells as a his-tagged protein, purified by affinity chromatography and used to develop an ELISA method to detect antibodies against PToV. This assay was evaluated using a serum collection including 45 samples from three commercial farms from Spain. High antibody prevalence against PToV was observed in the three farms, both in adult animals and in piglets, which could suggest that PToV might be endemic in Spanish porcine population. The ELISA method developed in this work could be useful in future epidemiological surveys about toroviruses.

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Section: Discussionmentioning

confidence: 99%

Molecular characterization of a new PToV strain. Evolutionary implications

et al. 2009

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“…The coronavirus HEs branch into five lineages (A through E), of which, saliently, those of groups A and B both originate from MHV strains. The HE proteins of toroviruses likewise divide into two porcine and two bovine lineages ( Figure 5); the HE protein reported for human torovirus [90,91] is a peculiar outlier, more related to that of BToV-BRV (74% sequence identity) than to any of the other torovirus HEs characterized thus far (not shown).…”

Section: Sequence Diversity Among Nidovirus He Proteinsmentioning

confidence: 92%

Structure, function and evolution of the hemagglutinin-esterase proteins of corona- and toroviruses

2006

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Virus attachment to host cells is mediated by dedicated virion proteins, which specifically recognize one or, at most, a limited number of cell surface molecules. Receptor binding often involves protein-protein interactions, but carbohydrates may serve as receptor determinants as well. In fact, many different viruses use members of the sialic acid family either as their main receptor or as an initial attachment factor. Sialic acids (Sias) are 9-carbon negatively-charged monosaccharides commonly occurring as terminal residues of glycoconjugates. They come in a large variety and are differentially expressed in cells and tissues. By targeting specific Sia subtypes, viruses achieve host cell selectivity, but only to a certain extent. The Sia of choice might still be abundantly present on non-cell associated molecules, on non-target cells (including cells already infected) and even on virus particles themselves. This poses a hazard, as high-affinity virion binding to any of such "false'' receptors would result in loss of infectivity. Some enveloped RNA viruses deal with this problem by encoding virion-associated receptor-destroying enzymes (RDEs). These enzymes make the attachment to Sia reversible, thus providing the virus with an escape ticket. RDEs occur in two types: neuraminidases and sialate-O-acetylesterases. The latter, originally discovered in influenza C virus, are also found in certain nidoviruses, namely in group 2 coronaviruses and in toroviruses, as well as in infectious salmon anemia virus, an orthomyxovirus of teleosts. Here, the structure, function and evolution of viral sialate-O-acetylesterases is reviewed with main focus on the hemagglutinin-esterases of nidoviruses.

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“…The variability of the HE gene within toroviruses is also remarkable. The HE gene is present in porcine, bovine, equine, and putative human toroviruses (Cornelissen et al, 1997;Duckmanton et al, 1999;Kroneman et al, 1998). Most newly characterized bovine torovirus variants seem to have emerged from a genetic exchange, during which the 3 end of the HE gene, the N gene, and the 3 nontranslated region of a bovine virus (Breda type strain) have been swapped for those of a porcine torovirus.…”

Section: Virus-specific Accessory Genes: Fast Adaptability To a New Nmentioning

confidence: 99%

Nidovirales: Evolving the largest RNA virus genome

et al. 2006

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This review focuses on the monophyletic group of animal RNA viruses united in the order Nidovirales. The order includes the distantly related coronaviruses, toroviruses, and roniviruses, which possess the largest known RNA genomes (from 26 to 32kb) and will therefore be called "large" nidoviruses in this review. They are compared with their arterivirus cousins, which also belong to the Nidovirales despite having a much smaller genome (13-16kb). Common and unique features that have been identified for either large or all nidoviruses are outlined. These include the nidovirus genetic plan and genome diversity, the composition of the replicase machinery and virus particles, virus-specific accessory genes, the mechanisms of RNA and protein synthesis, and the origin and evolution of nidoviruses with small and large genomes. Nidoviruses employ single-stranded, polycistronic RNA genomes of positive polarity that direct the synthesis of the subunits of the replicative complex, including the RNA-dependent RNA polymerase and helicase. Replicase gene expression is under the principal control of a ribosomal frameshifting signal and a chymotrypsin-like protease, which is assisted by one or more papain-like proteases. A nested set of subgenomic RNAs is synthesized to express the 3'-proximal ORFs that encode most conserved structural proteins and, in some large nidoviruses, also diverse accessory proteins that may promote virus adaptation to specific hosts. The replicase machinery includes a set of RNA-processing enzymes some of which are unique for either all or large nidoviruses. The acquisition of these enzymes may have improved the low fidelity of RNA replication to allow genome expansion and give rise to the ancestors of small and, subsequently, large nidoviruses.

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The novel hemagglutinin-esterase genes of human torovirus and Breda virus

Cited by 14 publications

References 25 publications

Molecular characterization of a new PToV strain. Evolutionary implications

Molecular characterization of a new PToV strain. Evolutionary implications

Structure, function and evolution of the hemagglutinin-esterase proteins of corona- and toroviruses

Nidovirales: Evolving the largest RNA virus genome

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