| 3' terminal nucleotide sequence of human astrovirus type 1 and routine detection of astrovirus nucleic acid and antigens. | human astrovirus type 1 was purified by caesium chloride density-gradient centrifugation and the virus was located using an immunodot blot technique with polyclonal rabbit serum, which reacted with all five serotypes. the virus banded with a density of 1.33 g/ml. rna was extracted from the purified virus, converted into double-stranded cdna, using an oligo(dt) primer, and cloned into plasmid and m13 vectors. the sequence of the 3' end of astrovirus rna adjacent to the poly(a) tract was determine ... | 1992 | 1430061 |
| the 3' terminal sequence of a human astrovirus. | we have determined the sequence for 1,000 bases from the 3' terminus of a human astrovirus serotype 1 isolated in newcastle. this is the first sequence reported for a representative of this virus family. we find one open reading frame which terminates 83 bases from a poly a tail. the 3' non-coding-region has similarities to some picornavirus termini. however the amino acids specified by the coding region have no significant homology to the picornavirus protein 3d, encoded at the 3' terminus of t ... | 1992 | 1605739 |
| cloning and characterization of human astrovirus immunoreactive epitopes. | we report the cloning of antigenic, protein-coding regions of human astrovirus serotype 1 that appear to be common to most, if not all, serotypes of human astrovirus. screening of lambda gt11 libraries identified three different but overlapping clones (a43, a35, and a1) and one independent clone (a14) that reacted with serum from a rabbit repeatedly immunized with purified astrovirus particles but not with its preimmunization serum. these clones were shown to be astrovirus specific. of note, a r ... | 1993 | 7679752 |
| use of a nested pcr method for the detection of astrovirus serotype 1 in human faecal material. | in this paper we describe a reverse-transcription nested polymerase chain reaction method for detecting human astrovirus serotype 1. it has been evaluated on 56 uk diarrhoeal stool specimens and six non-uk specimens. the method has greater sensitivity than electron microscopy and may be a useful test in areas such as the uk where this serotype predominates. | 1994 | 7700270 |
| typing of human astroviruses from clinical isolates by enzyme immunoassay and nucleotide sequencing. | a typing enzyme immunoassay (type-eia) was used to determine the antigenic types of 64 astrovirus-positive specimens from nine collections from seven countries. six of the seven known astrovirus types were detected in the collections, with hastv-1 predominating in all collections for one from the united kingdom. selected specimens were analyzed further by reverse transcriptase pcr and nucleotide sequencing of 348 bp within the capsid protein precursor region of the genome. the phylogenetic group ... | 1995 | 7790440 |
| the complete sequence of a human astrovirus. | we have determined the complete genomic sequence of human astrovirus serotype 1 isolated in newcastle upon tyne. the genome is 6813 nucleotides long and contains three sequential open reading frames (orfs). the two closest to the 5' end are linked by a ribosomal frameshifting motif and contain sequence motifs indicative of non-structural virus proteins: serine protease and rna-dependent rna polymerase. a nuclear addressing sequence is also located here. the 3' orf encodes the virion structural p ... | 1994 | 8021608 |
| the human astrovirus rna-dependent rna polymerase coding region is expressed by ribosomal frameshifting. | the genomic rna of human astrovirus serotype 1 (hast-1) contains three open reading frames (orfs), 1a, 1b, and 2. orf 1b is located downstream of, and overlaps, 1a, and it has been suggested on the basis of sequence analysis that expression of orf 1b is mediated through -1 ribosomal frameshifting. to examine this possibility, a cdna fragment containing the 1a-1b overlap region was cloned within a reporter gene and placed under the control of the bacteriophage sp6 promoter in a recombinant plasmi ... | 1994 | 8057439 |
| detection of human astrovirus serotype 1 by the polymerase chain reaction. | astroviruses are small, plus-strand rna viruses associated with diarrhoea, mostly in children. the diagnostic method commonly used is electron microscopy. we have designed a nested polymerase chain reaction (pcr) based on the recently reported nucleotide sequence of the 3' end of the genome of a human astrovirus serotype 1, the most common form. the pcr was positive for the ten serotype 1 samples tested, while being negative for all other viruses tested, including astrovirus type 2, 3, 4 and 5, ... | 1993 | 8227281 |
| identification and sequence determination of the capsid protein gene of human astrovirus serotype 1. | we present the sequence of an open reading frame (orf) at the 3' end of human astrovirus serotype 1. primer extension experiments showed that the rna expressing this gene is shorter than the complete orf, and could form a protein of m(r) 85,540. the protein was expressed by recombinant baculovirus and was recognized by anti-virion serum, indicating a structural role. sequence comparison indicates that astrovirus serotypes 1 and 2 differ markedly in the c-terminal half of the protein but are well ... | 1993 | 8293952 |
| seroprevalence of astrovirus types 1 and 6 in london, determined using recombinant virus antigen. | we have developed a microimmunofluorescence test (if) which uses cells infected with a recombinant baculovirus which expresses the capsid proteins of astrovirus types 1 or 6. the if test was sensitive and specific and the results for human astrovirus type 1 (hast-1) were comparable to those obtained by immune electronmicroscopy and radioimmunoassay. application of the test to a panel of 273 sera collected from patients and staff at two childrens hospitals in london showed that over 50% of the po ... | 1996 | 8760964 |
| construction of a genome-length cdna clone for human astrovirus serotype 1 and synthesis of infectious rna transcripts. | we have constructed a genome-length cdna clone for human astrovirus serotype 1. when a human colon cancer-derived cell line, caco-2, is transfected with rna transcribed in vitro from this cdna clone, infectious virus is produced at titers close to those observed after infection with intact astrovirus. a rodent cell line, bhk, which is largely refractory to astrovirus infection, was found to support efficient growth of the virus if transfected with viral rna. the high transfection efficiency seen ... | 1997 | 8995706 |
| application of electronmicroscopy, enzyme immunoassay, and rt-pcr to monitor an outbreak of astrovirus type 1 in a paediatric bone marrow transplant unit. | during 1997, an extensive outbreak of astrovirus occurred in a unit where paediatric patients were being treated for leukaemias and inherited immune deficiency disorders. prolonged shedding of virus for many months following infection was demonstrated in three patients who had undergone bone marrow transplantation. comparison of reverse transcription-polymerase chain reaction (rt-pcr), enzyme immunoassay (eia), and electronmicroscopy (em) to monitor the outbreak showed that many subclinical infe ... | 1999 | 10022805 |
| [antibody prevalence against astrovirus according to age groups]. | a study on the prevalence of antibodies against human astrovirus serotype 1 (hastv-1) and 2 (hastv-2) was carried out in 170 serum samples obtained from different age groups in tokyo and saitama, japan. prevalence of specific igg antibodies to both hastvs showed decreasing tendency after birth and reached a minimum at the 3-5 months age group. then, prevalence of antibodies to both serotypes increased after 6 months old, and nearly reach to 100% by the third year of life. the antibody titer to b ... | 1999 | 10423948 |
| avian nephritis virus (anv) as a new member of the family astroviridae and construction of infectious anv cdna. | the complete rna genome of the avian nephritis virus (anv) associated with acute nephritis in chickens has been molecularly cloned and sequenced. excluding the poly(a) tail, the genome comprises 6,927 nucleotides and contains three sequential open reading frames (orfs). the first orf (orf 1a) contains a sequence encoding a serine protease motif, and the second orf (orf 1b) has a sequence encoding an rna-dependent rna polymerase. orf 1a may be linked to the second orf by a ribosomal frameshifting ... | 2000 | 10954549 |
| molecular biology of astroviruses: selected highlights. | human astrovirus, the prototype of the astroviridae family, is a non-enveloped positive-strand rna virus with distinctive morphology. initially named for a characteristic 5-6 point star evident on the surface of faecally shed viral particles by direct electron microscopy, a recent study using cryoelectron microscopy and image reconstruction indicates that viral particles consist of a smoothly rippled, solid capsid decorated with short spikes. mechanisms underlying the assembly of these viral par ... | 2001 | 11444028 |
| proteolytic processing of a human astrovirus nonstructural protein. | to analyse the activity of the putative 3c-like serine protease encoded in open reading frame (orf)-1a of human astrovirus serotype 1 (hastv-1), orf-1a was transcribed and translated in vitro. translation products, identified by immunoprecipitation with specific antibodies against recombinant c-terminal orf-1a fragments, include the full-length 101 kda (p101) protein and a 38 kda band (p38). in addition, a 64 kda protein (p64) was immunoprecipitated by an anti-flag antibody when a flag epitope w ... | 2002 | 11752697 |
| processing of nonstructural protein 1a of human astrovirus. | astrovirus contains three open reading frames (orf) on its genomic rna, orf1a, orf1b, and orf2. orf1a encodes a 920-amino-acid (aa) nonstructural protein, nsp1a, which displays a 3c-like serine protease motif. little is known about the processing of nsp1a or whether the protease it contains is active and involved in autocatalytic processing. here we address both of these matters. intact and n-terminally deleted forms of orf1a from human astrovirus serotype 1 were expressed in bhk cells, and nsp1 ... | 2002 | 11799197 |
| studies on intracellular processing of the capsid protein of human astrovirus serotype 1 in infected cells. | astroviruses are non-enveloped, positive-strand rna viruses. their structural (capsid) protein is processed extracellularly into several smaller fragments which are found on the mature viral particle. in addition, intracellular cleavage of the capsid protein has been proposed. however, analysis of capsid protein processing has been hampered by the lack of antibodies to regions near the n and c termini of the protein. here we describe the construction of two infectious mutants of human astrovirus ... | 2002 | 12075088 |
| detection and characterisation of human astroviruses in children with acute gastroenteritis in blantyre, malawi. | in a 2-year hospital-based study of paediatric gastroenteritis in blantyre, malawi, astroviruses were detected by enzyme immunoassay in 15 (1.9%) of 786 inpatients and in 9 (2.3%) of 400 outpatients. greater disease severity was noted in children coinfected with human immunodeficiency virus (hiv). six human astrovirus (hastv) genotypes were identified, including hastv-1 (25%), hastv-2 (21%), hastv-3 (25%), hastv-4 (13%), hastv-5 (4%), and hastv-8 (13%). although astroviruses are not major causes ... | 2002 | 12116005 |
| structural requirements of astrovirus virus-like particles assembled in insect cells. | expression of the complete orf2 of human astrovirus serotype 1 (hastv-1) in the baculovirus system led to the formation of virus-like particles (vlps) of around 38 nm. the same kind of vlps were also obtained either with the expression of a truncated form of orf2 lacking the first 70 amino acids (aa), or with the same truncated form in which those 70 aa were replaced by the green fluorescent protein. all three kinds of vlps were equally recognized by an anti-hastv-1 polyclonal antibody and by tw ... | 2004 | 15542679 |
| different rates of (non-)synonymous mutations in astrovirus genes; correlation with gene function. | complete genome sequences of the astroviridae include human, non-human mammalian and avian species. a consensus topology of astroviruses has been derived from nucleotide substitutions in the full-length genomes and from non-synonymous nucleotide substitutions in each of the three orfs. analyses of synonymous substitutions displayed a loss of tree structure, suggesting either saturation of the substitution model or a deviant pattern of synonymous substitutions in certain virus species. | 2007 | 17343744 |
| astrovirus increases epithelial barrier permeability independently of viral replication. | astrovirus infection in a variety of species results in an age-dependent diarrhea; however, the means by which astroviruses cause diarrhea remain unknown. studies of astrovirus-infected humans and turkeys have demonstrated few histological changes and little inflammation during infection, suggesting that intestinal damage or an overzealous immune response is not the primary mediator of astrovirus diarrhea. an alternative contributor to diarrhea is increased intestinal barrier permeability. here, ... | 2007 | 17699569 |
| human astrovirus coat protein inhibits serum complement activation via c1, the first component of the classical pathway. | human astroviruses (hastvs) belong to a family of nonenveloped, icosahedral rna viruses that cause noninflammatory gastroenteritis, predominantly in infants. eight hastv serotypes have been identified, with a worldwide distribution. while the hastvs represent a significant public health concern, very little is known about the pathogenesis of and host immune response to these viruses. here we demonstrate that hastv type 1 (hastv-1) virions, specifically the viral coat protein (cp), suppress the c ... | 2008 | 17959658 |
| molecular characterization of astrovirus in stool samples from children in são paulo, brazil. | the purpose of this study was to characterize astrovirus in faecal samples collected from children with and without diarrhea in são paulo, brazil, grouped into two sets: epm and hu. detection and genotyping were carried out using reverse transcription nested polymerase chain reaction (rt-pcr) with specific primers directed towards the genome open reading frame 2 (orf2). results for epm set showed that 66/234 (28.2%) were positive: 28/94 (29.7%) from children with acute diarrhea, 14/45 (31.1%) wi ... | 2007 | 18209936 |
| genetic diversity of norovirus, sapovirus, and astrovirus isolated from children hospitalized with acute gastroenteritis in chiang mai, thailand. | norovirus (nv), sapovirus (sv), and human astrovirus (hastv) are important causes of acute gastroenteritis in infants and young children. this study investigated the prevalence of nv, sv, and hastv infections in children hospitalized with acute gastroenteritis in chiang mai, thailand from may 2000 to march 2002. fecal specimens were tested for nv, sv, and hastv by reverse transcription polymerase chain reaction (rt-pcr) using degenerate specific primers. these viruses were characterized further ... | 2008 | 18712816 |
| alternative cell lines to improve the rescue of infectious human astrovirus from a cdna clone. | a reverse genetics system for human astrovirus (hastv) was established previously; however, it has not been exploited mainly because cells used for virus packaging are not permissive, requiring several rounds of replication to obtain acceptable infectious virus. in this work, in the search for alternative permissive cell lines to be used as packaging cells, hek-293 and huh7.5.1 were tested. given that hastv infection in hek-293 showed differences with that in caco-2, the gold standard for hastv ... | 2011 | 22115787 |
| a novel method of real-time reverse-transcription loop-mediated isothermal amplification developed for rapid and quantitative detection of human astrovirus. | a one-step, real-time reverse-transcription loop-mediated isothermal amplification (rrt-lamp) method targeting the 5' end of the capsid gene for rapid and quantitative detection of human astrovirus serotype 1 (hastv 1) was developed. the assay is highly sensitive and comparable to real-time rt-pcr (rrt-pcr), with a detection limit of ∼100 rna copies per assay. the specificity of the method was validated by the absence of any cross-reaction with rna samples of hastv 2-8 and other gastroenteritis ... | 2012 | 23274752 |