Astroviruses are a type of
virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's 1 ...
that was first discovered in 1975 using
electron microscopes
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
following an outbreak of
diarrhea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
in humans.
In addition to humans, astroviruses have now been isolated from numerous mammalian animal species (and are classified as genus ''
Mamastrovirus
''Mamastrovirus'' is a genus of viruses, in the family ''Astroviridae
''Astroviridae'' is a family of non-enveloped ssRNA viruses that cause infections in different animals. The family name is derived from the Greek word ''astron'' ("star") r ...
'') and from avian species such as ducks, chickens, and turkey poults (classified as genus ''Avastrovirus''). Astroviruses are 28–35 nm diameter,
icosahedral
In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons".
There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrica ...
viruses that have a characteristic five- or six-pointed star-like surface structure when viewed by electron microscopy. Along with the
Picornaviridae
Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm i ...
and the
Caliciviridae
The ''Caliciviridae'' are a family of "small round structured" viruses, members of Class IV of the Baltimore scheme. Caliciviridae bear resemblance to enlarged picornavirus and was formerly a separate genus within the picornaviridae. They are p ...
, the Astroviridae comprise a third family of nonenveloped viruses whose
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
is composed of plus-
sense
A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of Stimulus (physiology), stimuli. (For example, in the human body, the brain which is part of the cen ...
, single-stranded RNA.
Astrovirus has a non-segmented, single stranded, positive sense
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
genome within a
non-enveloped icosahedral
capsid
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may ...
.
Human astroviruses have been shown in numerous studies to be an important cause of
gastroenteritis
Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
in young children worldwide.
In animals, Astroviruses also cause infection of the gastrointestinal tract but may also result in
encephalitis
Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, ...
(humans and cattle), hepatitis (avian) and nephritis (avian).
Microbiology
Taxonomy
The
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses (ICTV) authorizes and organizes the taxonomic classification of and the nomenclatures for viruses. The ICTV has developed a universal taxonomic scheme for viruses, and thus has the means to app ...
(ICTV) established ''Astroviridae'' as a viral family in 1995.
There have been over 50 astroviruses reported, although the ICTV officially recognizes 22 species.
The genus ''Avastrovirus'' comprises three species; Chicken astrovirus (Avian nephritis virus types 1–3), Duck astrovirus (Duck astrovirus C-NGB), and Turkey astrovirus (Turkey astrovirus 1). The genus ''Mamastrovirus'' includes Bovine astroviruses 1 and 2, Human astrovirus (types 1-8), Feline astrovirus 1, Porcine astrovirus 1, Mink astrovirus 1 and Ovine astrovirus 1.
Structure
![JVI](https://upload.wikimedia.org/wikipedia/commons/b/b2/JVI.02666-15_F1.large.jpg)
Astroviruses have a star-like appearance with five or six points. Their name is derived from the Greek word "astron" meaning star. They are
non-enveloped RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
viruses with cubic
capsid
A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may ...
s, approximately 28–35 nm in diameter with T=3 symmetry.
Human astroviruses are part of the Mammastrovirus genus and contains 8 serotypes. The human astrovirus capsid spikes have a distinct structure. The spike domain in particular has a 3-layered beta-sandwiches fold and a core, 6-stranded beta-barrel structure. The beta-barrel has a hydrophobic core. The triple-layered beta-sandwich is packed outside the beta-barrel. The spike also forms a dimer. This unique structure was found to be similar to the protein projections found on the capsid of the hepatitis E virus. The projection domain of the human astrovirus contains a receptor binding site for polysaccharides. The amino acid sequence of the astrovirus capsid protein does not have similar homology to other known viral proteins, but the closest would be hepatitis E virus.
Life cycle
Astroviruses infect birds and mammals through the
fecal-oral route. They have a
tissue tropism
Tissue tropism is the range of cells and tissues of a host that support growth of a particular pathogen, such as a virus, bacterium or parasite.
Some bacteria and viruses have a broad tissue tropism and can infect many types of cells and tissues. ...
for
enterocyte
Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells which line the inner surface of the small and large intestines. A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase its ...
s. Entry into the host cell is achieved by attachment to host receptors, which mediates endocytosis. Replication follows the
positive-strand RNA virus
Positive-strand RNA viruses (+ssRNA viruses) are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated int ...
replication model. Astrovirus RNA is infectious and functions as a
messenger RNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein.
mRNA is created during the p ...
for ORF1a and ORF1b. A frame-shifting mechanism between these two nonstructural polypeptides translates
RNA-dependent RNA polymerase
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template. This is in contrast to t ...
. In replication complexes near intracellular membranes, ORF1a and ORF1b are cleaved to generate individual nonstructural proteins that are involved in replication. The resulting subgenomic RNA contains ORF2 and encodes precursor capsid protein (VP90). VP90 is proteolytically cleaved during packaging and produces immature capsids made of VP70. Following encapsidation, immature capsids are released from the cell without lysis.
Extracellular virions are cleaved by Trypsin and form mature infectious virions.
Genome
![41598 2019 45889 Fig2 cropped HTML](https://upload.wikimedia.org/wikipedia/commons/c/c2/41598_2019_45889_Fig2_cropped_HTML.jpg)
Astroviruses have a
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
composed of a single strand of positive sense
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
. The strand has a
poly A tail at the
3' end, but no
5' cap. With the exclusion of polyadenylation at the
3' end, the genome is between 6.8–7.9 kb long. The genome is arranged into three
open reading frame
In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible readin ...
s (ORFs), with an overlap of approximately 70 nucleotides between ORF1a and ORF1b. The remaining ORF is known as ORF2.
ORF2 encode the structural proteins, which are -at least- VP26, VP29 and VP32, the most antigenic and immunogenic of these being VP26. This protein is probably involved in the first steps of viral infection, being a key factor in the biological cycle of astroviruses.
The human astrovirus genome mutation rate has been estimated to be 3.7×10
−3 nucleotide substitutions per site per year with the synonymous changes rate of 2.8×10
−3 nucleotide substitutions per site per year.
The capability for
genetic recombination
Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. In eukaryo ...
appears to be present in type-3 and type-4 human astroviruses,
and in porcine astrovirus strains.
Evolution
The ''Astroviridae'' capsid is related to those of the ''
Tymoviridae''. The non-structural region is related to the ''
Potyviridae
''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a ...
''. It appears that this group of viruses may have arise at some point in the past as a result of recombination event between two distinct viruses and that this even occurred at the junction of the structural and non-structural coding regions.
Species infected
Avastrovirus
![Viruses-09-00022-g001](https://upload.wikimedia.org/wikipedia/commons/9/98/Viruses-09-00022-g001.webp)
Avastrovirus 1–3 are associated with enteric infections in turkeys, ducks, chicken and guinea fowl. In turkey poults 1–3 weeks of age, some symptoms of enteritis include diarrhea, listlessness, liver eating and nervousness. These symptoms are usually mild but in cases of poult enteritis and mortality syndrome (PEMS), which has dehydration, immune dysfunction and anorexia as symptoms, mortality is high.
Post mortem
An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any dis ...
examination of the intestines of infected birds show fluid filled intestines. Hyperplasia of enterocytes is also observed in histopathology studies. However, in contrast to other enteric viruses, there isn't villous supply.
Avastrovirus species often infect extraintestinal sites such as the kidney or liver resulting in hepatitis and nephritis.
Birds infected by
avian nephritis virus
''Avastrovirus 2'', also called avian nephritis virus, is an astrovirus which causes 'avian nephritis' in chickens.
Causes: Infectious Stunting Syndrome — ISS — Baby Chick Nephritis — BCN.
The virus has been reported in Japan, Europe, US ...
typically die within 3 weeks of infection. The viral particles can be detected in fecal matter within 2 days and peak virus shedding occurs 4–5 days after infection. The virus can be found in the kidney, jejunum, spleen, liver and bursa of infected birds. Symptoms of this disease include diarrhea and weight loss. Necropsies show swollen and discolored kidneys and there is evidence of death of the epithelial cells and lymphocytic interstitial nephritis.
Another extraintestinal
avastrovirus
''Avastrovirus'' is a genus of viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bact ...
is avian hepatitis virus which infects ducks. Hepatitis in ducks caused by this duck astrovirus (DAstV) is often fatal.
In birds, ''
Avastrovirus
''Avastrovirus'' is a genus of viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bact ...
es'' are detected by antigen-capture ELISA. In the absence of vaccines, sanitation is the prevalent way to prevent ''
Avastrovirus
''Avastrovirus'' is a genus of viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bact ...
'' infections.
Mamastrovirus
Mamastroviruses often cause
gastroenteritis
Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
in infected mammals. In animals,
gastroenteritis
Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
is usually undiagnosed because most astrovirus infections are asymptomatic. However, in mink and humans, astroviruses can cause diarrhea and can be fatal. The incubation period for ''
Mamastrovirus
''Mamastrovirus'' is a genus of viruses, in the family ''Astroviridae
''Astroviridae'' is a family of non-enveloped ssRNA viruses that cause infections in different animals. The family name is derived from the Greek word ''astron'' ("star") r ...
'' is 1–4 days. When symptoms occur, the incubation period is followed by diarrhea for several days. In mink, symptoms include increased secretion from
apocrine glands
Apocrine () glands are a type of exocrine gland, which are themselves a type of gland, i.e. a group of cells specialized for the release of secretions. Exocrine glands secrete by one of three means: holocrine, merocrine and apocrine. In apocri ...
.
Human astroviruses are associated with gastroenteritis in children and immunocompromised adults. 2–8% of acute non-bacterial gastroenteritis in children is associated with human astrovirus. These viral particles are usually detected in epithelial cells of the duodenum.
In sheep, ovine astroviruses were found in the villi of the small intestine.
Mamastrovirus
''Mamastrovirus'' is a genus of viruses, in the family ''Astroviridae
''Astroviridae'' is a family of non-enveloped ssRNA viruses that cause infections in different animals. The family name is derived from the Greek word ''astron'' ("star") r ...
es also cause diseases of the nervous system. These diseases most commonly occur in cattle, mink and humans. In cattle, this occurs sporadically and infects individual animals. Symptoms of this infection include seizure, lateral recumbency and impaired coordination. Histological examinations showed neuronal necrosis and gliosis of the cerebral cortex, cerebellum, spinal cord and brainstem.
Signs and symptoms in humans
Members of a relatively new virus family, the astroviridae, astroviruses are now recognised as a cause of
gastroenteritis
Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
in children, whose immune systems are underdeveloped, and elderly adults, whose immune systems are generally somewhat compromised. Presence of viral particles in fecal matter and in epithelial intestinal cells indicate that the virus replicates in the gastrointestinal tract of humans. The main symptoms are
diarrhoea
Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
, followed by nausea,
vomiting
Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose.
Vomiting can be the result of ailments like Food-poisoning, foo ...
,
fever
Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...
, malaise and abdominal pain. Some research studies have shown that the incubation period of the disease is approximately three to four days. Astrovirus infection is not usually a severe situation and only in some rare cases leads to
dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
. The severity and variation in symptoms correlates with the region the case develops in. This could be due to climatic factors influencing the life cycle or transmission method for that particular strain of Astrovirus. Malnutrition and immunodeficiency tend to exacerbate the condition, leading to more severe cases or secondary conditions that could require hospital care. Otherwise, infected people do not need hospitalization because symptoms will reduce by themselves, after 2 to 4 days.
Diagnosis
Electron microscopy
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
, enzyme-immunoassay (
ELISA
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...
),
immunofluorescence
Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specif ...
, and
polymerase chain reaction
The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) t ...
have all been used for detecting virus particle, antigens or viral nucleic acid in the stools of infected people.
A method using real-time RT-PCR, which can detect all human astrovirus genotypes, has been reported.
Some
RT-qPCR
A real-time polymerase chain reaction (real-time PCR, or qPCR) is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR (i.e., in real ...
techniques are able to simultaneously detect human astroviruses and other enteric viruses associated with
gastroenteritis
Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydra ...
. Microarrays are also used to differentiate between the eight different human astrovirus serotypes.
Pathogenesis
Astroviruses cause gastroenteritis by causing destruction of the intestinal epithelium, leading to the inhibition of usual absorption mechanism, loss of secretory functions, and decrease in epithelial permeability in the intestines. Inflammatory responses were seen to not affect astrovirus pathogenesis.
Epidemiology
Astroviruses are associated with 5–9% of the cases of gastroenteritis in young children.
Humans of all ages are susceptible to astrovirus infection, but children, the elderly, and those that are
immunocompromised
Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
are most prone. A study of intestinal disease in the UK, published in 1999, determined incidence as 3.8/1000 patient years in the community (95%
CI, range 2.3–6.4), the fourth most common known cause of viral gastroenteritis.
Studies in the USA have detected astroviruses in the stools of 2–9% of children presenting symptoms; illness is most frequent in children younger than two years, although outbreaks among adults and the elderly have been reported. Early studies carried out in
Glasgow
Glasgow ( ; sco, Glesca or ; gd, Glaschu ) is the most populous city in Scotland and the fourth-most populous city in the United Kingdom, as well as being the 27th largest city by population in Europe. In 2020, it had an estimated popul ...
demonstrated that a significant proportion of babies excreting virus particles did not exhibit gastrointestinal symptoms.
Seroprevalence
Seroprevalence is the number of persons in a population who test positive for a specific disease based on serology (blood serum) specimens; often presented as a percent of the total specimens tested or as a proportion per 100,000 persons tested. As ...
studies carried out in the
US have shown that 90% of children have antibody to
HastV-1 by age 9, suggesting that (largely asymptomatic) infection is common. Looking at the pattern of disease, it suggests that antibodies provide protection through adult life until the antibody titre begins to decline later in life.
The occurrence of astrovirus infections vary depending on the season. In
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
climates, infection is highest during winter months possibly due to lower temperatures which enhance the stability of the virus. This is in contrast to
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
regions where prevalence is highest during the rainy season. The seasonal distribution in tropical climates can be explained by the effect of rain particularly on the breakdown of
sanitation
Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...
in developing countries.
Human astroviruses are transmitted by the
fecal–oral route
The fecal–oral route (also called the oral–fecal route or orofecal route) describes a particular route of transmission of a disease wherein pathogens in fecal particles pass from one person to the mouth of another person. Main causes of fecal ...
. The main mode of astrovirus transmission is by contaminated food and water. Young children in childcare backgrounds or adults in military barracks are most likely to develop the disease. Human astroviruses may be released in large quantities in the stool of infected individuals and contaminate
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
,
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
and
marine water
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appr ...
due to inadequate
wastewater treatment
Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be returned to the water cycle. Once returned to the water cycle, the effluent creates an acceptable impact on the environme ...
. Fruits and vegetables grown in such contaminated water may also act as sources of viral infection. Poor food handling practices, poor hand hygiene and contamination of inanimate objects are other factors that encourage
enteric
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
virus transmission.
Astroviruses can also be transmitted to humans from other animal species. In comparison to individuals who had no contact with turkey, turkey
abattoir
A slaughterhouse, also called abattoir (), is a facility where animals are slaughtered to provide food. Slaughterhouses supply meat, which then becomes the responsibility of a packaging facility.
Slaughterhouses that produce meat that is no ...
workers were three times more likely to test positive for antibodies against turkey astroviruses. Furthermore, some human, duck, chicken and turkey astroviruses are
phylogenetically
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
related and share genetic features.
Prevention
Human astroviruses can be prevented by detection and inactivation in contaminated food and water in addition to disinfection of contaminated fomites.
Treatment
Astrovirus Immunoglobulin
In a study by Bjorkholm et al., a 78-year-old patient diagnosed with Waldenstrom's macroglobulinemia was given 0.4 g/kg of astrovirus immunoglobulin for four days, and the symptoms dissolved leading to a full recovery from astrovirus; however, further testing has yet to be completed.
''Achyrocline bogotensis'' antiviral therapy
In a study by Tellez et al., extracts from a plant ''
Achyrocline bogotensis'' was used to develop an antiviral therapy for both rotavirus and astrovirus. ''Achyrocline bogotensis'' was commonly used for skin and urinary infections. Drug testing methodology involved application of the extract to cell for pre-treatment (blocking), direct viral activity (evidence of killing the virus), and treatment (a decrease in the viral load after an infection is established). The extract demonstrated direct viral activity by killing astroviruses directly and treatment by leading to a decrease in the viral load after an established infection. A pre-treatment effect was not evident during the experiment.
Timeline
1975: Appleton and Higgins first discovered astrovirus in stool samples of children suffering from gastroenteritis by using electron microscopy (EM)
1975: Madeley and Cosgrove named the 20–30 nm viral particle Astrovirus based on the star-like EM (electron microscopy) appearance
1976-1992: Lee and Kurtz serotyped 291 astrovirus stool samples in Oxford; discovered serotypes 6 and 7
1981: Lee and Kurtz were able to grow astrovirus in tripsin-dependent tissue culture by using human embryo kidney cells (HEK)
1985: Lee and Kurtz discover two serotypes of astrovirus that are used to type 13 strains of community-acquired astrovirus
1987: Gray et al. discovered that a 22-day long gastroenteritis outbreak in an elderly home was caused by astrovirus type 1 and calicivirus
1988: Hermann and Hudson use antigen characterization of HEK grown astroviruses to develop monoclonal antibodies
1992: Cruz et al. analyzed 5,000 stool samples 7.5% of the diarrheal diseases found in Guatemalan ambulatory rural children were caused by astroviruses
1993: Jiang et al. sequence astrovirus RNA and determine the presence of three ORFs and ribosomal frameshifting
1993: Monroe et al. classify subgenomic data for astrovirus, providing support for astrovirus to be classified as a viral family
1994: Oishi et al. determine astrovirus as the main cause of gastroenteritis in schools in Katano City, Osaka, Japan
1995: Bjorkholm elt al. conducted a clinical study, and 78-year-old male Waldenström's macroglobulinemia patient with astrovirus-associated gastroenteritis was successfully treated with intravenous immunoglobulin
1995: Jonassen et al. uses PCR to detect all known serotypes (7) of astrovirus
1995: In their sixth report, ICTV establishes Astroviridae as a viral family
1996: Glass et al. states an epidemiological shift regarding astrovirus due to improvements in RT-PCT (reverse transcription PCR), monoclonal antibodies, and enzyme immunoassays (EIA); astroviruses are now considered one of the main causes of diarrheal disease worldwide
1996: Palombo and Bishop the epidemiology of astrovirus infections in children suffering from gastroenteritis in Melbourne, Australia (data collected include total incidence, genetic diversity, serotype characterization)
1998: Unicomb et al. conduct a clinical study in Bangladesh and conclude astrovirus infections involving nosocomial, acute, and persistent diarrheal diseases
1998: Gaggero et al. identify human astrovirus type 1 to be the main cause of acute gastroenteritis in Chilean children
1999: Bon et al. discover astrovirus in a gastroenteritis outbreak in Dijon, France
2001: Dennehy et al. collected stool samples from hospitalized children suffering from acute gastroenteritis; astrovirus was determined the second leading cause of gastroenteritis after rotavirus
2002: Guix et al. completes an epidemiological study on the presence of astrovirus in Barcelona, Spain; the total incidence of astrovirus in 2,347 samples was 4.95 with a peak in the number of cases in the winter
2003: Basu et al. discovered astrovirus in 2.7% of stool samples collected from 346 children suffering from gastroenteritis in Gaborone, Botswana
2009: Finkbeiner et al. used Sanger sequencing to discover a novel astrovirus in stool samples from children suffering from an acute gastroenteritis outbreak at a childcare center
2009: Using RT-PCR, Kapoor et al. discover novel astrovirus strains HMOAstV species A, B, C which are very similar to astroviruses found in mink and ovine species; this showed that the virus may have the ability to jump species
Recent findings
December 2016: Yuan et al. discovered that the recovery rate for astroviruses was 8.24% for a novel centrifugal method developed to concentrate human enteroviruses from water samples.
18 December 2016: Lum et al. demonstrated the capacity of human astrovirus (particularly Neuroinvasive astrovirus (VA1-HMO-C)) to become an emerging opportunistic infection. An 8-month-old bone marrow transplant patient died of VA1/HMO-C encephalitis following the transplant. The presence of VA1/HMO-C was confirmed after positive PCR test results.
24 January 2017: Human astrovirus (particularly serotypes 1, 4, 6, and 8) were found in 4.2% of the samples collected from children suffering from acute gastroenteritis in Nara Prefecture, Japan.
February 2017: Cortez et al. conducted a retrospective study on persistent infections in pediatric oncology patients and determined human astrovirus to be the main cause of gastroenteritis in immunocompromised patients.
April 2017 (electronically published 28 December 2016): Bennett and Gunson developed a novel multiplex RT-PCR diagnostic technique to detect the presence of a variety of inflectional intestinal diseases (IID) including astrovirus, adenovirus, rotavirus, and sapovirus from stool samples.
References
External links
Viralzone: ''Astroviridae''ICTVAfrican wildlife diseases
{{Taxonbar, from=Q752185
Viral diseases
Gastroenterology
Foodborne illnesses
Riboviria