| sequence of the genomic rna of nudaurelia beta virus (tetraviridae) defines a novel virus genome organization. | the monopartite genome of nudaurelia beta virus, the type species of the betatetravirus genus of the family tetraviridae, consists of a single-stranded positive-sense rna (ss+rna) of 6625 nucleotides containing two open reading frames (orfs). the 5' proximal orf of 5778 nucleotides encodes a protein of 215 kda containing three functional domains characteristic of rna-dependent rna polymerases of ss+rna viruses. the 3' proximal orf of 1836 nucleotides, which encodes the 66-kda capsid precursor pr ... | 1999 | 10329566 |
| reverse transcription of a naturally occurring nonretroviral rna produces a precise deletion in the majority of its cdna products. | a precise, reproducible deletion made during in vitro reverse transcription of rna2 from the icosahedral positive-stranded helicoverpa armigera stunt virus (tetraviridae) is described. the deletion, located between two hexamer repeats, is a 50-base sequence that includes one copy of the hexamer repeat. only the moloney murine leukemia virus reverse transcriptase and its derivative superscript i, carrying a deletion of the carboxy-terminal rnase h region, showed this response, indicating a templa ... | 2000 | 10868914 |
| analysis of the capsid processing strategy of thosea asigna virus using baculovirus expression of virus-like particles. | thosea asigna virus (tav), a putative member of the genus betatetravirus of the family tetraviridae, is predicted to have a novel capsid expression strategy compared with other characterized tetraviruses. the capsid precursor protein is cleaved twice to generate three proteins. two of the proteins, l (58.3 kda) and s (6.8 kda), are incorporated into the tav virion. the third, non-structural protein, produced from the n terminus of the precursor protein, is up to 17 kda in size and is of unknown ... | 2001 | 11125178 |
| infection of its lepidopteran host by the helicoverpa armigera stunt virus (tetraviridae). | techniques of microscopy and histopathology were employed to study the positive-sense, single-stranded rna virus, the helicoverpa armigera stunt virus (hasv; omegatetravirus, tetraviridae) infecting its caterpillar host. infection of the virus per os during the first three instars of larval development is virulent and leads to rapid stunting and mortality. in contrast, no detectable symptoms occur in later larval development, signifying a high degree of developmental resistance. a quantitative s ... | 2002 | 12383435 |
| maturation of a tetravirus capsid alters the dynamic properties and creates a metastable complex. | the assembly of monomeric protein subunits into a viral capsid is a finely tuned molecular process. in response to subtle changes in environmental conditions, this supramolecular complex can dramatically reorganize. defining the forces that control this structure and the cooperative action of subunits has implications for biology and nanotechnology. the small icosahedral rna tetravirus family members nudaurelia omega capensis (nomegav) and helicoverpa armigera stunt virus (hasv) can be purified ... | 2005 | 15749119 |
| effective control of a field population of helicoverpa armigera by using the small rna virus helicoverpa armigera stunt virus (tetraviridae: omegatetravirus). | the first comprehensive field trial using an insect small rna virus as a control agent on a cropping system was conducted with the helicoverpa armigera stunt virus (family tetraviridae, genus omegatetravirus, hasv). the virus was semipurified, quantified, and applied at two rates, 4 x 10(15) and 4 x 10(14) virus particles/ha, with minimal formulation on sorghum against the bollworm helicoverpa armigera (hübner). for comparison, a commercial preparation of helicoverpa zea single-nucleopolyhedrovi ... | 2005 | 16539102 |
| subcellular localization and live-cell imaging of the helicoverpa armigera stunt virus replicase in mammalian and spodoptera frugiperda cells. | whilst their structure has been well studied, there is little information on the replication biology of tetraviruses because of the lack of suitable tissue-culture cell lines that support virus replication. in this study, the potential site of helicoverpa armigera stunt virus replication was investigated by transient expression of the replicase protein fused to enhanced green fluorescent protein (egfp) in mammalian and insect cells. when egfp was present at the c terminus of the protein, fluores ... | 2010 | 20107015 |
| providence virus (family: carmotetraviridae) replicates vrna in association with the golgi apparatus and secretory vesicles. | providence virus (prv) is the sole member of the family carmotetraviridae (formerly tetraviridae) sharing the characteristic t=4 capsid architecture with other tetravirus families. despite significant structural similarities, prv differs from other tetraviruses in terms of genome organization, non-structural protein sequence and regulation of gene expression. in addition, it is the only tetravirus that infects tissue culture cells. previous studies showed that in persistently infected helicoverp ... | 2013 | 23343628 |
| membrane targeting of an alpha-like tetravirus replicase is directed by a region within the rna-dependent rna polymerase domain. | the members of the family tetraviridae are small positive-sense insect rna viruses that exhibit stringent host specificity and a high degree of tissue tropism, suggesting that complex virus-host interactions are likely to occur during infection and viral replication. the alpha-like replicase of helicoverpa armigera stunt virus (hasv) (genus omegatetravirus) has been proposed to associate with membranes of the endocytic pathway, which is similar to semliki forest virus, sindbis virus and rubella ... | 2012 | 22535773 |
| sequence of rna2 of the helicoverpa armigera stunt virus (tetraviridae) and bacterial expression of its genes. | the complete nucleotide sequence of rna2 of helicoverpa armigera stunt virus (hasv), a member of the tetraviridae, was determined by characterization of cloned cdna and pcr products and direct sequencing of genomic rna. the capped, positive sense, single-stranded rna is 2478 nucleotides in length and has two overlapping open reading frames (orfs) likely to be cistrons which are situated between terminal non-coding regions of 282 and 168 bases, 5' and 3', respectively. extensive secondary structu ... | 1995 | 9049325 |
| an encapsidated viral protein and its role in rna packaging by a non-enveloped animal rna virus. | alphatetraviruses are small (+) ssrna viruses with non-enveloped, icosahedral, t=4 particles that assemble from 240 copies of a single capsid protein precursor. this study is focused on the mechanisms underlying selection and packaging of genomic vrnas by helicoverpa armigera stunt virus. we demonstrate that the viral protein, p17, is packaged at low levels (between 4 and 8 copies per capsid) raising the possibility of icosahedral asymmetry in wild-type particles. p17 promotes packaging of vrna2 ... | 2015 | 25577149 |
| binding and entry of a non-enveloped t=4 insect rna virus is triggered by alkaline ph. | tetraviruses are small, non-enveloped, rna viruses that exclusively infect lepidopteran insects. their particles comprise 240 copies of a single capsid protein precursor (cp), which undergoes autoproteolytic cleavage during maturation. the molecular mechanisms of capsid assembly and maturation are well understood, but little is known about the viral infectious lifecycle due to a lack of tissue culture cell lines that are susceptible to tetravirus infection. we show here that binding and entry of ... | 2016 | 27614703 |
| isolation and identification of a new tetravirus from dendrolimus punctatus larvae collected from yunnan province, china. | in this study, dendrolimus punctatus tetravirus (dptv) has been identified as a new member of the genus omegatetravirus of the family tetraviridae that may be related serologically to nudaurelia capensis omega virus (nomegav). dptv particles are isometric, with a diameter of about 40 nm and a buoyant density of 1.281 g cm(-3) in cscl. the virus has two capsid proteins (of 62 500 and 6800 da) and two single-stranded rna molecules (rna1 and rna2), which are 5492 and 2490 nt long, respectively. rna ... | 2005 | 15722541 |
| replication-independent assembly of an insect virus (tetraviridae) in plant cells. | infectious virions of the insect rna virus helicoverpa armigera stunt virus (hasv; omegatetravirus, tetraviridae) were assembled in cultured plant protoplasts of nicotiana plumbaginifolia in the absence of detectable replication. assembly of the virus, which has not been grown in cell culture, required cotransfection of a dna plasmid expressing the hasv capsid gene in combination with either genomic rna or with dna plasmids carrying the complete cdnas to the two hasv genomic rnas. each cdna was ... | 2001 | 11543656 |
| the specificity of helicoverpa armigera stunt virus infectivity. | helicoverpa armigera stunt virus (hasv) is a member of the tetraviridae family of rna viruses whose replication and expression strategies are not well understood due to the absence of an in vitro cell culture system. we set out to find such a system for hasv by screening an array of 13 insect and 1 mammalian cell culture lines with both virus particle infection and genomic rna transfection. no cell line was found to be permissive for replication, although entry of genomic rna was verified. the a ... | 1999 | 10486228 |
| induction of apoptosis in saccharomyces cerevisiae results in the spontaneous maturation of tetravirus procapsids in vivo. | the tetraviridae are a family of small, non-enveloped, insect rna viruses consisting of one or two single-stranded, positive-sense genomic rnas encapsidated in an icosahedral capsid with t=4 symmetry. tetravirus procapsids undergo maturation when exposed to a low ph environment in vitro. while the structural biology of the conformational changes that mediate acid-dependent maturation is well understood, little is known about the significance of acid-dependent maturation in vivo. to address this ... | 2007 | 17412989 |