Nidovirales: Evolving the largest RNA virus genome

By Alexander E. Gorbalenya, L. Enjuanes, J. Ziebuhr, E. Snijder. Virus Research, 2006

921 citations recorded by the source corpus.

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 32 kb) 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 (13–16 kb). 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.

Subfields: Animal Science and Zoology, Cardiology and Cardiovascular Medicine, Infectious Diseases

View Paper: https://www.semanticscholar.org/paper/fce6cf96a49471d2080b80aa320be95a462d327d

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Citations in the corpus

Genomic Characterization of a Newly Discovered Coronavirus Associated with Acute Respiratory Distress Syndrome in Humans (2012, background): “These are translated from the genomic mRNA to produce polyproteins pp1a and, following Ϫ1 ribosomal frameshifting, pp1ab, which are subsequently cleaved into 15 or 16 nonstructural proteins (nsps) (19, 23, 26) .”
Zn2+ Inhibits Coronavirus and Arterivirus RNA Polymerase Activity In Vitro and Zinc Ionophores Block the Replication of These Viruses in Cell Culture (2010, background): “This large group of positive-strand RNA (+RNA) viruses includes major pathogens of humans and livestock, such as severe acute respiratory syndrome coronavirus (SARS-CoV), other human coronaviruses, the arteriviruses equine arteritis virus (EAV), and porcine reproductive and respiratory syndrome viru”
Nsp3 of coronaviruses: Structures and functions of a large multi-domain protein (2017, background): “It is the enveloped positive-sense single-stranded RNA (+ssRNA) virus with the largest genome of all known RNA viruses thus far (Brian and Baric, 2005; Gorbalenya et al., 2006).”
The Evolution and Emergence of RNA Viruses (2009, background): “How is such a size increase possible without a mutational meltdown? The expanded genome size in the coronaviruses and roniviruses is principally due to the presence of a very large (>20 000 nt) replicase gene, and one which is composed of multiple functional domains (Gorbalenya et al. 2006) (Fig.”
SARS-Coronavirus Replication Is Supported by a Reticulovesicular Network of Modified Endoplasmic Reticulum (2008, methodology): “We have now employed ET to analyze the replication structures of SARS-CoV, a prominent member of the coronavirus group which—at about 7,000 amino acids— encodes the largest known þRNA virus replicase [14].”