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At least 19 recordsLinked to original sources
PubMed1997

Outbreak of gastroenteritis in military recruits associated with serotype 3 astrovirus infection.

A serotype 3 astrovirus was identified in stool samples from an outbreak of acute gastroenteritis that occurred among military recruits in France. Sixteen stools samples and eight pairs of acute- and convalescent-phase serum were collected from affected individuals. Astrovirus was detected in two stool samples by electron microscopy and in four stool samples by reverse transcriptase-polymerase chain reaction (RT-PCR). Seroconversion to the astrovirus present in one stool was detected in seven patients by using solid-phase immune electron microscopy (SPIEM) and dot blot. For three patients, the serological results were consistent with the PCR results, indicating that astrovirus was a cause of gastroenteritis in these young adults. This study describes the characterization of the serotype 3 astrovirus associated with this outbreak. The virus has a buoyant density in cesium chloride of 1.365 gm/ml and contains two proteins immuno-precipitated with rabbit serum. Only the larger protein was recognized by immunoblotting using a convalescent-phase human serum. The protein composition of this virus differs from that reported for serotype 1 astrovirus, indicating heterogeneity in the capsid composition among astrovirus serotypes.

Adult↗
PubMed1998

Prevalence of enteric viruses in human immunodeficiency virus seropositive patients in Venezuela.

The prevalence of enteric viruses associated with gastroenteritis was determined in 125 stool samples from patients infected with the human immunodeficiency virus (HIV), with or without diarrhea. Diagnostic assays included enzyme immunoassays for the identification of rotavirus, adenovirus, and Norwalk virus; polyacrylamide gel electrophoresis for atypical rotaviruses and picobirnaviruses and polymerase chain reaction for astrovirus. Enteric viruses were detected in 6.4% (8 of 125) of the stools collected: five (4.0%) samples positive for adenoviruses, and three (2.3%) samples positive for picobirnaviruses were detected. No rotavirus, astrovirus, or Norwalk virus were observed. Only one of the viruses identified (adenovirus) was found in a sample from a patient with diarrhea. Viruses were detected in 10% of the patients with AIDS, 14% of the symptomatic patients, and none of the asymptomatic persons. These results do not support a major role for enteric viruses in the diarrhea suffered by HIV-infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1999

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 infections, mainly in children aged > 3 years could only be detected by RT-PCR. Use of RT-PCR revealed that several patients were infected earlier and shed virus for longer than by using EM or EIA. The virus responsible for the outbreak was identified as HAstV-1 and was shown to have a sequence that differed from a strain obtained in 1988.

Astroviridae Infections↗
PubMed2000

Genomic characterization of human astrovirus type 6 Katano virus and the establishment of a rapid and effective reverse transcription-polymerase chain reaction to detect all serotypes of human astrovirus.

We previously reported that human astrovirus type 6 (HAstV T6) was the etiologic agent of a large-scale outbreak of acute gastroenteritis that occurred in 1991 in Katano City, Osaka, Japan [Oishi et al., 1994]. The two representative strains, Katano virus K23 and K24, have been analyzed by sequencing the open reading frame 2 (ORF2) region after amplification by reverse transcription-polymerase chain reaction (RT-PCR). The ORF2 region of HAstV T6 strains, including K23, was found to be about 20 bp smaller than those of other types. There was 94% nucleotide sequence identity and 95% amino acid sequence identity between K23 and K24, with the Oxford strains belonging to HAstV T6. The high homology of the ORF2 region between the Katano and Oxford strains shows intratype genomic stability, irrespective of time and place of virus isolation. Comparing sequences of ORF2 of different HAstV serotypes, we established a rapid and highly sensitive detection system for HAstV types using RT-PCR with the AC230/AC1' primer set designed from the 5'-terminal end region of ORF2. This RT-PCR system seems very useful in detecting at least two different viruses in a single PCR test tube using AC230/AC1' in addition to the NV81/82, SM82 primer sets. Thus, our rapid and effective detection system may contribute to the epidemiologic characterization of astrovirus infections as well as Norwalk-like viruses.

Amino Acid Sequence↗
PubMed2001

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 particles have not been fully elucidated. However, studies of two full-length cDNA clones of human astrovirus serotype 1 suggest that capsid residue Thr227 plays a critical role in the assembly of infectious viral progeny. The development of a full-length clone (pAVIC) from which infectious RNA can be transcribed has also facilitated studies of the viral 3C-like serine protease, encoded in ORF1a. These studies demonstrate that the full-length ORF1a product (101 kDa) is processed in vitro to an N-terminal 64 kDa fragment and a C-terminal 38 kDa fragment. Mutation of the predicted catalytic triad inhibits proteolysis. In other studies based on modifications of pAVIC, preliminary evidence supports the feasibility of developing a reporter cell line to facilitate astrovirus detection.

Amino Acid Sequence↗
PubMed2001

Molecular epidemiology of human astroviruses.

Human astroviruses (HAstVs) are associated with 5-9 percent of cases of gastroenteritis in young children. Seven serotypes (HAstV-1 to -7), which correlate with genotypes, have been defined by using immune typing methods. We have used partial nucleotide sequence information from the capsid protein gene for molecular typing of 29 unique human astrovirus strains obtained from prospective studies of children with gastroenteritis in Egypt and Malawi. HAstV-1 was the most commonly detected strain, consistent with previous studies, but a surprising variety of strains were identified in both collections. An eighth astrovirus type, HAstV-8, has been defined on the basis of the complete capsid protein gene sequence and was detected in both collections analysed in this study. Although HAstV-8 and HAstV-4 strains segregate into well resolved clades by analysis of sequences from the region encoding protein P2 (VP32), the pair-wise distances between these types are less than those between strains of the other serotypes. In contrast, analysis of sequences from the region encoding protein P3 unambiguously resolve HAstV-4 and HAstV-8 strains, consistent with their classification as distinct serotypes. Overall, strains representing six of the eight serotypes were detected in two collections of samples from prospective studies of gastroenteritis in young children indicating that multiple astrovirus types are frequently co-circulating within communities.

Gastroenteritis↗
PubMed2001

Gastroenteritis viruses: an overview.

Acute gastroenteritis is among the most common illnesses of humankind, and its associated morbidity and mortality are greatest among those at the extremes of age, children and the elderly. In developing countries, gastroenteritis is a common cause of death in children < 5 years that can be linked to a wide variety of pathogens. In developed countries, while deaths from diarrhoea are less common, much illness leads to hospitalization or doctor visits. Much of the gastroenteritis in children is caused by viruses belonging to four distinct families--rotaviruses, caliciviruses, astroviruses and adenoviruses. Other viruses, such as the toroviruses, picobirnaviruses, picornavirus (the Aichi virus), and enterovirus 22, may play a role as well. Viral gastroenteritis occurs with two epidemiologic patterns, diarrhoea that is endemic in children and outbreaks that affect people of all ages. Viral diarrhoea in children is caused by group A rotaviruses, enteric adenoviruses, astroviruses and the caliciviruses; the illness affects all children worldwide in the first few years of life regardless of their level of hygiene, quality of water, food or sanitation, or type of behaviour. For all but perhaps the caliciviruses, these infections provide immunity from severe disease upon reinfection. Epidemic viral diarrhoea is caused primarily by the Norwalk-like virus genus of the caliciviruses. These viruses affect people of all ages, are often transmitted by faecally contaminated food or water, and are therefore subject to control by public health measures. The tremendous antigenic diversity of caliciviruses and short-lived immunity to infection permit repeated episodes throughout life. In the past decade, the molecular characterization of many of these gastroenteritis viruses has led to advances both in our understanding of the pathogens themselves and in development of a new generation of diagnostics. Application of these more sensitive methods to detect and characterize individual agents is just beginning, but has already opened up new avenues to reassess their disease burden, examine their molecular epidemiology, and consider new directions for their prevention and control through vaccination, improvements in food and water quality and sanitary practices.

Adenoviruses, Human↗
PubMed1987

Comparative pathology of infection by novel diarrhoea viruses.

Examination of diarrhoeic faeces in the electron microscope often reveals viruses that are presumed to be enteropathogenic. Lesions caused by novel rotaviruses were similar to those of group A rotaviruses, but enterocyte syncytia were seen which are probably pathognomonic for novel rotaviruses. In adenovirus infection in piglets, mature enterocytes were infected and destroyed; intranuclear inclusion bodies were seen in infected enterocytes. Calici-like viruses infected mature enterocytes in calves and the lesions were similar to those described in humans infected with calici-like viruses; in both host species it was impossible to demonstrate virus particles in enterocytes examined in the electron microscope. The Breda virus infected villi and crypts in the lower small intestine and the surface and crypts in the large intestine; it was the only enteropathogenic virus to show this distribution of infection and lesions. Astrovirus infection in lambs was comparable to a mild rotavirus infection, but in calves the epithelium of the dome villi of Peyer's patches was infected. Parvovirus in cats and dogs infected and destroyed small intestinal crypt cells, causing dilated crypts and stunted villi; intranuclear inclusion bodies were prominent.

Adenoviridae Infections↗
PubMed1987

The diagnostic gap in diarrhoeal aetiology.

It is well established that rotaviruses of group A are the most important cause of severe diarrhoea in children. The causes of most cases of infectious diarrhoea still remain unidentified, however, and there must be other viruses to be found. 'Novel' rotaviruses have recently been discovered, mainly in animals (serogroups B and C in pigs and humans, D in birds, and one or more further groups in sheep and other mammals). Except for the group B virus which has caused widespread outbreaks of quite severe diarrhoea in adults in China (still not reported from outside China) these novel rotaviruses are rarities in the human and probably represent uncommon zoonotic infections. We speculate that the Chinese virus might have arisen by reassortment of genetic segments of animal group B viruses or perhaps by mutation, and so became infectious for man. The problem of identifying and determining the importance of small round viruses is reviewed. It seems likely that the group of small, round structured viruses, including Norwalk and the viruses of plainly calicivirus morphology, are all representatives of a whole group of enteric caliciviruses. Until they can be more easily cultivated it will be difficult to make diagnostic reagents available to all. Astroviruses and genuine parvoviruses have been found by many people in many countries. Astroviruses are probably more important as pathogens in lambs than in children or calves; parvoviruses can only be established as significant in epidemics. The coronavirus-like particles, first found in Vellore and Bristol, are still enigmatic and their role in diarrhoea is uncertain. Toroviridae, recently discovered as causes of diarrhoea in ungulates, do not seem to be at all important as causes of diarrhoea in humans. Possibly fruitful approaches to future searches are outlined: firstly to make more extensive use of immuno-electron microscopy; and secondly to try to improve existing tissue culture systems to make them more sensitive to enteric viruses.

Animals↗
PubMed1987

Astroviruses: human and animal.

The name astrovirus was used by Madeley and Cosgrove in 1975 to describe a small round virus (approximately 28 nm diameter) with star-like appearance on electron microscopy. It was first seen in faeces from a few children with gastroenteritis. An aetiological role in gastroenteritis has since been confirmed. The virus causes a mild illness after an incubation period of 3-4 days. Antibody studies indicate that infection is widespread and, in Britain, mainly occurs in the 2-5 year age group. Outbreaks occur in, for example, institutions and paediatric wards. The virus usually spreads by the faecal-oral route but food- or water-borne outbreaks have occurred. Strains of astrovirus have been isolated from many animals including calf, lamb, pig, cat, dog, duck and turkey. The lamb strain can cause gastroenteritis but the bovine strain did not cause diarrhoea in gnotobiotic calves. Infected turkeys have scours, and infection in ducklings causes haemorrhagic hepatitis with a mortality up to 25%. Five human serotypes have been described, all antigenically distinct from the bovine and ovine strains. The human astrovirus does not replicate in conventional tissue cultures but undergoes a non-productive cycle in human embryo kidney cells, and productive replication in the presence of trypsin. It is a positive-strand RNA virus, which is acid stable (pH3), survives at 60 degrees C for five but not 10 minutes and, like the enteroviruses, resists inactivation by alcohols. It has a density of 1.35-1.37 g/ml in caesium chloride.

Animals↗
PubMed1987

Small round viruses: classification and role in food-borne infections.

Since the first observation of Norwalk virus in the electron microscope in 1972, many different small virus particles in the size range 20-40 nm have been described world-wide in association with outbreaks of gastroenteritis. Progress characterizing these agents has been hampered by the relatively small numbers of particles present in clinical material and the lack of success in culturing them. Although the relationship between some of these viruses remains confusing, a number of distinct groups has emerged, based on morphological features and limited physical data. Immuno-electron microscopy has proved valuable in detecting viruses but the addition of antibody can mask surface morphological features. Examination of viruses in negatively stained preparations without added antibody has revealed distinct morphological differences and viruses previously thought to be simply antigenic variants within the Norwalk group of viruses clearly belong to other groups. Preliminary evidence suggests that one human virus unrelated to Norwalk has a single-stranded DNA genome and is a parvovirus. Some groups have been implicated in outbreaks of food-borne gastroenteritis, particularly after the consumption of shellfish, and their role in other food-borne and water-borne outbreaks is being increasingly recognized.

Caliciviridae↗
PubMed2002

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 of gastroenteritis among children admitted to hospital in Blantyre, concomitant HIV infection appears to be a risk factor for increased severity of disease.

Acute Disease↗
PubMed2003

Infantile viral gastroenteritis: on the way to closing the diagnostic gap.

A total of 305 faecal specimens collected from children under the age of 5 who presented with symptoms of acute gastroenteritis either as inpatients at Addenbrooke's Hospital (N = 100) or to General Practitioners in East Anglia (N = 205) during 1999-2001 were tested for the presence of rotavirus, norovirus, sapovirus, enteric adenoviruses (Group F, serotypes 40 and 41), and astrovirus. An aetiologic agent was found in 184 specimens (60.3%). The most commonly found single viral pathogen was rotavirus (27.9%), followed by norovirus (13.4%), enteric adenoviruses (7.9%), astrovirus (2.3%), and sapovirus (1%). Mixed infections were observed in 27 specimens (8.9%), and no aetiologic agent was found in over a third of the specimens tested. These data demonstrate that the diagnostic gap can be reduced considerably through the use of molecular amplification and detection techniques. However, additional work is required to reduce this deficit further by optimising sampling algorithms and by identifying other agents associated with viral gastroenteritis.

Adenoviruses, Human↗
PubMed2001

Genetic analysis of the capsid region of astroviruses.

Eight serotypes of human astroviruses (HAstV-1 to HAstV-8) have been described. To date, the entire genomes of HAstV-1 and HAstV-2 as well as the ORF2 sequences of HAstV-1-6 and 8 have been reported. In this study, the ORF2 sequences of seventeen strains of HAstVs originating from different countries were determined, as well as the sequence ORF2 of one porcine astrovirus (PAstV) strain. Afterwards, comparison of the capsid protein precursors encoded by ORF2 of 46 strains of HAstVs, PAstV, and feline astrovirus (FAstV) was carried out. A phylogenetic tree showed eight genogroups of HAstVs that corresponded exactly to the serotypes. HAstV-3 and 7 were the most closely related, whereas HAstVs, FAstV, and PAstV segregated from each other. Compared to a PAstV, a FAstV is closer to HAstVs. Furthermore, the capsid protein precursors were divided into four regions (after amino acid residues 424, 688, and 776, respectively) based on sequence identity. Region I was the most conserved, and FAstV was very close in identity to HAstVs. Two amino acid motifs in region I were predicted to contain the common antigenic epitopes. Region II was relatively variable. Deletions and insertions were characteristic of region III, and region IV was relatively conserved. To our knowledge, this is the first comparative sequence analysis of the capsid protein precursors of eight serotypes of HAstVs as well as two animal astroviruses (FAstV and PAstV).

Amino Acid Motifs↗
PubMed2001

Characterisation of a South African human astrovirus as type 8 by antigenic and genetic analyses.

Human astroviruses (HAstV) can, on the basis of immunoassays using type-specific rabbit antisera, be classified into eight serotypes that correlate with genotypes. Very few isolates of HAstV type 8 have been described and there is a paucity of data available with regard to the antigenic and genetic relationships between HAstV type 8 (HAstV-8) and HAstV types 1 (HAstV-1) to 7 (HAstV-7). A wild-type HAstV from a South African paediatric patient with diarrhoea was analysed antigenically, by immune electron microscopy and enzyme immunoassay, and genetically in selected regions of the ORF1a, ORF1b and ORF2 and characterised as a HAstV-8. This HAstV-8 strain exhibited greatest homology with HAstV-4 in the 5' end of the capsid gene and ORF1a and 1b, and greatest homology with HAstV-5 in the 3' end of the capsid region. This study confirms, by both antigenic and genetic analyses, that HAstV-8 represents a distinct antigenic and genotype and is the first report of a HAstV-8 from a hospitalised paediatric patient with diarrhoea in southern Africa.

Amino Acid Sequence↗
PubMed2003

Persistent gastroenteritis in children infected with astrovirus: association with serotype-3 strains.

The relationship between cases of persistent diarrhoea and the levels and type of human astrovirus was investigated. The potential correlation between human astrovirus excretion levels and the occurrence of protracted gastroenteritis was elucidated after quantifying astroviruses in faecal samples by a competitive RT-PCR. This assay was developed employing an internal RNA standard constructed for this purpose and showed a threshold of positivity of 3.4 x 10(4) genomes per gram of faeces. By this procedure, the levels of astrovirus, belonging to serotypes 1, 2, 3, 4, and 8, in faecal samples could be ascertained to range from 3.4 x 10(8) to 1 x 10(13) per gram of faeces. The mean viral titre in the serotype 3-containing faeces was higher than in any of the other serotype-containing samples. In children with no background disease, persistent gastroenteritis cases were detected in 8.5% of the astrovirus infections, and 37.5% of those were associated with astrovirus type 3 infection. In addition, 42.9% of astrovirus 3 isolates were implicated with persistent cases, some of them lasting for 3 months. Other type 3 isolates, detected in the faeces in very large numbers, caused severe gastroenteritis.

Astroviridae Infections↗
PubMed2004

Prevalence and characterization of astroviruses in Argentinean children with acute gastroenteritis.

Among viral agents causing gastroenteritis, human astroviruses (HAstVs) take second or third place, after rotaviruses and caliciviruses, as the most frequent cause of illness. The aims of this study were to determine the prevalence of HAstV infection and to characterize the circulating HAstV strains in children with diarrhea under 3 years of age treated between 1995 and 1998 at out- or in-patient facilities of the children's hospital in Mendoza, Argentina. Reverse transcription-polymerase chain reaction (RT-PCR) and enzyme immunoassay (EIA) were used to detect HAstVs in stool specimens. Positive specimens were tested further by EIA and/or sequenced to type detected HAstV strains. HAstVs were detected in 40 (3.7%) of 1,070 samples that were rotavirus and calicivirus-negative: 14 (3.5%) of 402 from outpatients and 26 (3.9%) of 668 from inpatients. HAstV infection tended to be more severe in children during their first year of life: 18 (4.7%) of 383 HAstV-positive children 0-11 months old were hospitalized versus 8 (2.8%) of 285 children 1 year of age or older (P = 0.29). Type 1 (HAstV-1) was the most common type (41%), followed by HAstV-4 (25%), HAstV-2 (13%), HAstV-3 (13%), and HAstV-5 (8%). In this first epidemiological study of HAstV infection in this region, we confirmed HAstV to be a cause of severe gastroenteritis in children, more often among children younger than 12 months of age. HastV-4 caused 25% of HastV infections in Mendoza, although it has been detected commonly elsewhere. Distinct genetic lineages were apparent but their epidemiological significance remains to be demonstrated.

Acute Disease↗
PubMed1979

Astrovirus infection in volunteers.

An extract and a filtrate prepared from feces of a child with mild gastroenteritis were shown by electron microscopy to contain numerous astrovirus particles and were given to eight volunteers by mouth. One subject developed diarrheal illness and concurrently shed large amounts of astrovirus in feces, and one other had mild constitutional symptoms with a lower level of virus shedding. Nine other volunteers were given fecal filtrate from the volunteer with diarrhea, and astrovirus shedding subsequently occurred in two of them. The syndrome accompanying virus shedding appeared distinct from that associated with the "W" agent in previous experiments. Thirteen of 16 astrovirus-inoculated subjects subsequently developed a rise in titer of the homologous antibody in serum. It was concluded that astrovirus causes a transmissible infection that is of low pathogenicity for adults. Immunofluorescence of human embryo kidney cells inoculated with astrovirus and shown by electron microscopy to contain 28 nm virus-like particles was used both to detect virus in feces and to assay astrovirus antibody.

Adolescent↗