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Advances in Virus Research 2023Astroviruses encapsidate a positive-sense, single-stranded RNA genome into ∼30nm icosahedral particles that infect a wide range of mammalian and avian species, but... (Review)
Review
Astroviruses encapsidate a positive-sense, single-stranded RNA genome into ∼30nm icosahedral particles that infect a wide range of mammalian and avian species, but their biology is not well understood. Human astroviruses (HAstV) are divided into three clades: classical HAstV serotypes 1-8, and novel or non-classical HAstV of the MLB and VA clades. These viruses are part of two genogroups and phylogenetically cluster with other mammalian astroviruses, highlighting their zoonotic potential. HAstV are a highly prevalent cause of nonbacterial gastroenteritis, primarily in children, the elderly and immunocompromised. Additionally, asymptomatic infections and extraintestinal disease (e.g., encephalitis), are also observed, mostly in immunocompetent or immunocompromised individuals, respectively. While these viruses are highly prevalent, no approved vaccines or antivirals are available to prevent or treat infections. This is in large part due to their understudied nature and the limited understanding of even very basic features of their life cycle and pathogenesis at the cellular and organismal level. This review will summarize molecular features of human astrovirus biology, pathogenesis, and tropism, and then focus on two stages of the viral life cycle, namely entry and egress, since these are proven targets for therapeutic interventions. We will further highlight gaps in knowledge in hopes of stimulating future research into these understudied viruses.
Topics: Animals; Child; Humans; Aged; Mamastrovirus; Gastroenteritis; Genotype; Phylogeny; Mammals
PubMed: 37832992
DOI: 10.1016/bs.aivir.2023.08.001 -
Voprosy Virusologii Dec 2023Bastroviruses were discovered in the Netherlands in 2016 in human stool samples and show partial genetic similarities to astroviruses and hepatitis E viruses. Their...
INTRODUCTION
Bastroviruses were discovered in the Netherlands in 2016 in human stool samples and show partial genetic similarities to astroviruses and hepatitis E viruses. Their association with disease onset has not yet been established.
MATERIALS AND METHODS
Metagenomic sequencing of fecal samples of bats collected in the Russian Federation in 2023 was performed. Two almost complete genomes of bastroviruses were assembled. The zoonotic potential of these viruses was assessed using machine learning methods, their recombination was studied, and phylogenetic trees were constructed.
RESULTS
A nearly complete bastrovirus genome was de novo assembled in one of the samples, and it was used to assemble another genome in another sample. The zoonotic potential of the virus from one of these samples was estimated as high. The existence of recombination between structural and non-structural polyproteins was demonstrated.
CONCLUSION
Two bastrovirus genomes were assembled, phylogenetic and recombination analyses were performed, and the zoonotic potential was evaluated.
Topics: Animals; Humans; Astroviridae; Astroviridae Infections; Phylogeny; Chiroptera; Genetic Variation
PubMed: 38156566
DOI: 10.36233/0507-4088-192 -
Viruses May 2021Astroviruses (AstVs) are non-enveloped, positive single-stranded RNA viruses that cause a wide range of inflammatory diseases in mammalian and avian hosts. The T = 3... (Review)
Review
Astroviruses (AstVs) are non-enveloped, positive single-stranded RNA viruses that cause a wide range of inflammatory diseases in mammalian and avian hosts. The T = 3 viral capsid is unique in its ability to infect host cells in a process driven by host proteases. Intercellular protease cleavages allow for viral egress from a cell, while extracellular cleavages allow for the virus to enter a new host cell to initiate infection. High-resolution models of the capsid core indicate a large, exposed region enriched with protease cleavage sites. The virus spike protein allows for binding to target cells and is the major target for naturally occurring and engineered neutralizing antibodies. During maturation, the capsid goes through significant structural changes including the loss of many surface spikes. The capsid interacts with host membranes during the virus life cycle at multiple stages such as assembly, host cell entry and exit. This review will cover recent findings and insights related to the structure of the capsid and its function. Further understanding of the viral capsid structure and maturation process can contribute to new vaccines, gastric therapeutics, and viral engineering applications.
Topics: Capsid; Capsid Proteins; Crystallography; Humans; Mamastrovirus; Models, Molecular; Virion
PubMed: 34062934
DOI: 10.3390/v13050821 -
Viruses Dec 2016Astroviruses are one of the leading causes of pediatric gastroenteritis worldwide and are clinically importantly pathogens in the elderly and immunocompromised... (Review)
Review
Astroviruses are one of the leading causes of pediatric gastroenteritis worldwide and are clinically importantly pathogens in the elderly and immunocompromised populations. Although the use of cell culture systems and small animal models have enhanced our understanding of astrovirus infection and pathogenesis, little is known about the immune response to astrovirus infection. Studies from humans and animals suggest that adaptive immunity is important in restricting classic and novel astrovirus infections, while studies from animal models and cell culture systems suggest that an innate immune system plays a role in limiting astrovirus replication. The relative contribution of each arm of the immune system in restricting astrovirus infection remains unknown. This review summarizes our current understanding of the immune response to astrovirus infection and highlights some of the key questions that stem from these studies. A full understanding of the immune response to astrovirus infection is required to be able to treat and control astrovirus-induced gastroenteritis.
Topics: Adaptive Immunity; Animals; Astroviridae; Astroviridae Infections; Humans; Immune Evasion; Immunity, Innate
PubMed: 28042824
DOI: 10.3390/v9010001 -
Viruses Aug 2022Goose astroviruses (GoAstVs) are small non-enveloped viruses with a genome consisting of a single-stranded positive-sense RNA molecule. A novel GoAstV was identified in... (Review)
Review
Goose astroviruses (GoAstVs) are small non-enveloped viruses with a genome consisting of a single-stranded positive-sense RNA molecule. A novel GoAstV was identified in Shandong in 2016 and quickly spread to other provinces in China, causing gout in goslings, with a mortality rate of approximately 50%. GoAstV can also cause gout in chickens and ducks, indicating its ability to cross the species barrier. GoAstV has only been reported in China, where it has caused serious losses to the goose-breeding industry. However, in view of its cross-species transmission ability and pathogenicity in chickens and ducks, GoAstV should be a concern to poultry breeding globally. As an emerging virus, there are few research reports concerning GoAstV. This review summarizes the current state of knowledge about GoAstV, including the epidemiology, evolution analysis, detection methods, pathogenicity, pathogenesis, and potential for cross-species transmission. We also discuss future outlooks and provide recommendations. This review can serve as a valuable reference for further research on GoAstV.
Topics: Animals; Astroviridae Infections; Avastrovirus; Bird Diseases; China; Ducks; Geese; Gout; Phylogeny
PubMed: 36016381
DOI: 10.3390/v14081759 -
Annual Review of Virology Sep 2017Astroviruses are nonenveloped, positive-sense single-stranded RNA viruses that cause gastrointestinal illness. Although a leading cause of pediatric diarrhea, human... (Review)
Review
Astroviruses are nonenveloped, positive-sense single-stranded RNA viruses that cause gastrointestinal illness. Although a leading cause of pediatric diarrhea, human astroviruses are among the least characterized enteric RNA viruses. However, by using in vitro methods and animal models to characterize virus-host interactions, researchers have discovered several important properties of astroviruses, including the ability of the astrovirus capsid to act as an enterotoxin, disrupting the gut epithelial barrier. Improved animal models are needed to study this phenomenon, along with the pathogenesis of astroviruses, particularly in those strains that can cause extraintestinal disease. Much like for other enteric viruses, the current dogma states that astroviruses infect in a species-specific manner; however, this assumption is being challenged by growing evidence that these viruses have potential to cross species barriers. This review summarizes these remarkable facets of astrovirus biology, highlighting critical steps toward increasing our understanding of this unique enteric pathogen.
Topics: Animals; Astroviridae Infections; Capsid; Chickens; Diarrhea; Disease Models, Animal; Gastroenteritis; Humans; Intestinal Mucosa; Mamastrovirus; Mice; Permeability; Phylogeny; Species Specificity; Swine
PubMed: 28715976
DOI: 10.1146/annurev-virology-101416-041742 -
BioMed Research International 2022In recent years, an infection in geese caused by goose astrovirus (GAstV) has repeatedly occurred in coastal areas of China and rapidly spread to inland provinces. The... (Review)
Review
In recent years, an infection in geese caused by goose astrovirus (GAstV) has repeatedly occurred in coastal areas of China and rapidly spread to inland provinces. The infection is characterized by joint and visceral gout and is fatal. The disease has caused huge economic losses to China's goose industry. GAstV is a nonenveloped, single-stranded, positive-sense RNA virus. As it is a novel virus, there is no specific classification. Here, we review the current understanding of GAstV. The virus structure, isolation, diagnosis and detection, innate immune regulation, and transmission route are discussed. In addition, since GAstV can cause gout in goslings, the possible role of GAstV in gout formation and uric acid metabolism is discussed. We hope that this review will inform researchers to rapidly develop effective methods to prevent and treat this disease.
Topics: Animals; Astroviridae Infections; Avastrovirus; Geese; Genome, Viral; Gout; Phylogeny; Poultry Diseases
PubMed: 36072471
DOI: 10.1155/2022/1635373 -
Journal of Clinical Virology : the... Sep 2016Astroviruses are small, non-enveloped, single-stranded positive RNA viruses that belong to the Astroviridae family. While classical human astroviruses (HAstV) are a... (Review)
Review
Astroviruses are small, non-enveloped, single-stranded positive RNA viruses that belong to the Astroviridae family. While classical human astroviruses (HAstV) are a well-recognized cause of acute non-bacterial diarrhea among young children worldwide, novel astroviruses, named HAstV-MLB and HAstV-VA/HMO, have been identified recently in humans by molecular assays. They are phylogenetically more related to animal astroviruses than to classical human astroviruses, thus suggesting cross-species transmission. Serological studies demonstrated a surprisingly high seroprevalence in certain populations and highlighted a high infection rate in the early years of life. Although their pathogenic role has not yet been clearly determined, novel astrovirus RNA sequences have been identified in different biological specimens of symptomatic patients, including the feces, plasma, cerebrospinal fluid, and brain biopsies. Thus, there is evidence that they could contribute not only to digestive tract infection, but also to unexpected clinical syndromes, notably encephalitis and meningitis. Severe infections affect mainly immunocompromised patients. These findings indicate that novel astroviruses should be considered in the differential diagnosis of immunocompromised patients with meningitis or encephalitis of unknown origin.
Topics: Astroviridae Infections; Humans; Mamastrovirus; Phylogeny; Seroepidemiologic Studies
PubMed: 27434149
DOI: 10.1016/j.jcv.2016.07.004 -
PLoS Biology Jul 2023During the last decade, the detection of neurotropic astroviruses has increased dramatically. The MLB genogroup of astroviruses represents a genetically distinct group...
During the last decade, the detection of neurotropic astroviruses has increased dramatically. The MLB genogroup of astroviruses represents a genetically distinct group of zoonotic astroviruses associated with gastroenteritis and severe neurological complications in young children, the immunocompromised, and the elderly. Using different virus evolution approaches, we identified dispensable regions in the 3' end of the capsid-coding region responsible for attenuation of MLB astroviruses in susceptible cell lines. To create recombinant viruses with identified deletions, MLB reverse genetics (RG) and replicon systems were developed. Recombinant truncated MLB viruses resulted in imbalanced RNA synthesis and strong attenuation in iPSC-derived neuronal cultures confirming the location of neurotropism determinants. This approach can be used for the development of vaccine candidates using attenuated astroviruses that infect humans, livestock animals, and poultry.
Topics: Child; Animals; Humans; Child, Preschool; Aged; Mamastrovirus; Astroviridae Infections; Gastroenteritis; Capsid Proteins; Capsid; Phylogeny
PubMed: 37459343
DOI: 10.1371/journal.pbio.3001815 -
Viruses Mar 2022The chicken astrovirus (CAstV) is a ubiquitous enteric RNA virus that has been associated mainly with conditions, such as the runting-stunting syndrome, severe kidney... (Review)
Review
The chicken astrovirus (CAstV) is a ubiquitous enteric RNA virus that has been associated mainly with conditions, such as the runting-stunting syndrome, severe kidney disease, visceral gout, and white chick syndrome, in broiler-type chickens worldwide. Sequence analysis of the capsid genes' amino acids of the strains involved in these conditions reveals a genetic relationship and diversity between and within the CAstV genogroups and subgroups based on phylogenetic analysis, genetic distance (p-dist), and pathogenicity. While the two genogroups (A and B) are demarcated phylogenetically, their pairwise amino acid sequence identity is 39% to 42% at a p-dist of 0.59 to 0.62. Group-A consists of three subgroups (Ai, Aii, and Aiii) with an inter- and intra-subgroup amino acid identity of 78% to 82% and 92% to 100%, respectively, and a p-dist of 0.18 to 0.22. On the other hand, the six subgroups (Bi, Bii, Biii, Biv, Bv, and Bvi) in Group-B, with a p-dist of 0.07 to 0.18, have an inter- and intra-subgroup amino acid identity of 82% to 93% and 93% to 100%, respectively. However, these groupings have little to no effect on determining the type of CAstV-associated pathology in chickens.
Topics: Amino Acids; Animals; Astroviridae Infections; Avastrovirus; Chickens; Phylogeny; Poultry Diseases
PubMed: 35458451
DOI: 10.3390/v14040722