At least six small alternative-frame open reading frames (ORFs) overlapping well-characterized SARS-CoV-2 genes have been hypothesized to encode accessory proteins. Researchers have used different... Show moreAt least six small alternative-frame open reading frames (ORFs) overlapping well-characterized SARS-CoV-2 genes have been hypothesized to encode accessory proteins. Researchers have used different names for the same ORF or the same name for different ORFs, resulting in erroneous homological and functional inferences. We propose standard names for these ORFs and their shorter isoforms, developed in consultation with the Coronaviridae Study Group of the International Committee on Taxonomy of Viruses. We recommend calling the 39 codon Spike-overlapping ORF ORF2b; the 41, 57, and 22 codon ORF3a-overlapping ORFs ORF3c, ORF3d, and ORF3b; the 33 codon ORF3d isoform ORF3d-2; and the 97 and 73 codon Nucleocapsid-overlapping ORFs ORF9b and ORF9c. Finally, we document conflicting usage of the name ORF3b in 32 studies, and consequent erroneous inferences, stressing the importance of reserving identical names for homologs. We recommend that authors referring to these ORFs provide lengths and coordinates to minimize ambiguity caused by prior usage of alternative names. Show less
In human adenoviruses (HAdV), 240 copies of the 14.3-kDa minor capsid protein IX stabilize the capsid. Three N-terminal domains of protein IX form triskelions between hexon capsomers. The C... Show moreIn human adenoviruses (HAdV), 240 copies of the 14.3-kDa minor capsid protein IX stabilize the capsid. Three N-terminal domains of protein IX form triskelions between hexon capsomers. The C-terminal domains of four protein IX monomers associate near the facet periphery. The precise biological role of protein IX remains enigmatic. Here we show that deletion of the protein IX gene from a HAdV-5 vector enhanced the reporter gene delivery 5 to 25-fold, specifically to Coxsackie and Adenovirus Receptor (CAR)-negative cell lines. Deletion of the protein IX gene also resulted in enhanced activation of peripheral blood mononuclear cells. The mechanism for the enhanced transduction is obscure. No differences in fiber loading, integrin-dependency of transduction, or factor-X binding could be established between protein IX-containing and protein IX-deficient particles. Our data suggest that protein IX can affect the cell tropism of HAdV-5, and may function to dampen the innate immune responses against HAdV particles. (C) 2010 Elsevier Inc. All rights reserved. Show less
Insertion of nucleotide sequences encoding "tags" that can be expressed in specific viral proteins during an infection is a useful strategy for purifying viral proteins and their functional... Show moreInsertion of nucleotide sequences encoding "tags" that can be expressed in specific viral proteins during an infection is a useful strategy for purifying viral proteins and their functional complexes from infected cells and/or for visualizing the dynamics of their subcellular location over time. To identify regions in the poliovirus polyprotein that could potentially accommodate insertion of tags, transposon-mediated insertion mutagenesis was applied to the entire nonstructural protein-coding region of the poliovirus genome, followed by selection of genomes capable of generating infectious, viable viruses. This procedure allowed us to identify at least one site in each viral nonstructural protein, except protein 2C, in which a minimum of five amino acids could be inserted. The distribution of these sites is analyzed from the perspective of their protein structural context and from the perspective of virus evolution. Published by Elsevier Inc. Show less
Eggink, D.; Melchers, M.; Wuhrer, M.; Montfort, T. van; Dey, A.K.; Naaijkens, B.A.; ... ; Sanders, R.W. 2010
The HIV-1 envelope glycoprotein complex (Env) is the focus of vaccine development aimed at eliciting humoral immunity. Env's extensive and heterogeneous N-linked glycosylation affects folding,... Show moreThe HIV-1 envelope glycoprotein complex (Env) is the focus of vaccine development aimed at eliciting humoral immunity. Env's extensive and heterogeneous N-linked glycosylation affects folding, binding to lectin receptors, antigenicity and immunogenicity. We characterized recombinant Env proteins and virus particles produced in mammalian cells that lack N-acetylglucosaminyltransferase I (GnTI), an enzyme necessary for the conversion of oligomannose N-glycans to complex N-glycans. Carbohydrate analyses revealed that trimeric Env produced in GnTI(-/-) cells contained exclusively oligomannose N-glycans, with incompletely trimmed oligomannose glycans predominating. The folding and conformation of Env proteins was little affected by the manipulation of the glycosylation. Viruses produced in GnTI(-/-) cells were infectious, indicating that the conversion to complex glycans is not necessary for Env entry function, although virus binding to the C-type lectin DC-SIGN was enhanced. Manipulating Env's N-glycosylation may be useful for structural and functional studies and for vaccine design. (C) 2010 Elsevier Inc. All rights reserved. Show less
The Tetraviridae is a family of non-enveloped positive-stranded RNA insect viruses that is defined by the T=4 symmetry of virions. We report the complete Euprostema elaeasa virus (EeV) genome... Show moreThe Tetraviridae is a family of non-enveloped positive-stranded RNA insect viruses that is defined by the T=4 symmetry of virions. We report the complete Euprostema elaeasa virus (EeV) genome sequence of 5698 nt with no poly(A) tail and two overlapping open reading frames, encoding the replicase and capsid precursor, with similar to 67% amino acid identity to Thosea asigna virus (TaV). The N-terminally positioned 17 kDa protein is released from the capsid precursor by a NPGP motif EeV has 40 nm non-enveloped isometric particles composed of 58 and 7 kDa proteins. The 3'-end of TaV/EeV is predicted to form a conserved pseudoknot. Replicases of TaV and EeV include a newly delineated VPg signal mediating the protein priming of RNA synthesis in dsRNA Birnaviridae. Results of rooted phylogenetic analysis of replicase and capsid proteins are presented to implicate recombination between monopartite tetraviruses, involving autonomization of a sgRNA, in the emergence of bipartite tetraviruses. They are also used to revise the Tetraviridae taxonomy. (C) 2009 Elsevier Inc. All rights reserved. Show less
The RNA of all tymoviruses, a group of ssRNA plant viruses, has a base composition that is different from that of most other viruses. The excess of cytosines (35-42%) and the low number of... Show moreThe RNA of all tymoviruses, a group of ssRNA plant viruses, has a base composition that is different from that of most other viruses. The excess of cytosines (35-42%) and the low number of guanosines (15-17%) must impel an RNA structure with a relatively low amount of base pairing and a high incidence of unpaired cytosines. These unpaired cytosines probably function in RNA-protein interactions. To gain insight into the way the RNA is positioned inside the virion, the secondary structure has been determined of a part of TYMV RNA, including the so-called tymobox, the coat protein gene, and the 3' untranslated region, by structure probing, sequence comparison, and computer predictions. Conservation of secondary structure elements in tymoviruses is not high and does not parallel the conservation of the primary structure. A combination of structure prediction and probing experiments, however, results in a model consisting of structured domains of 100-200 nucleotides interspersed by long unpaired cytosine-rich regions. The latter may interact with the coat protein inside the virion. The structure of some functionally interesting regions of the 3' part of TYMV RNA is also discussed. (C) 1996 Academic Press, Inc. Show less
Olsthoorn, R.R.C.L.; Garde, G.; Dayhuff, T.; Atkins, J.F.; Duin, J. van 1995
