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Nature Jul 2022Enteric viruses like norovirus, rotavirus and astrovirus have long been accepted as spreading in the population through fecal-oral transmission: viruses are shed into...
Enteric viruses like norovirus, rotavirus and astrovirus have long been accepted as spreading in the population through fecal-oral transmission: viruses are shed into feces from one host and enter the oral cavity of another, bypassing salivary glands (SGs) and reaching the intestines to replicate, be shed in feces and repeat the transmission cycle. Yet there are viruses (for example, rabies) that infect the SGs, making the oral cavity one site of replication and saliva one conduit of transmission. Here we report that enteric viruses productively and persistently infect SGs, reaching titres comparable to those in the intestines. We demonstrate that enteric viruses get released into the saliva, identifying a second route of viral transmission. This is particularly significant for infected infants, whose saliva directly transmits enteric viruses to their mothers' mammary glands through backflow during suckling. This sidesteps the conventional gut-mammary axis route and leads to a rapid surge in maternal milk secretory IgA antibodies. Lastly, we show that SG-derived spheroids and cell lines can replicate and propagate enteric viruses, generating a scalable and manageable system of production. Collectively, our research uncovers a new transmission route for enteric viruses with implications for therapeutics, diagnostics and importantly sanitation measures to prevent spread through saliva.
Topics: Astroviridae; Breast Feeding; Cells, Cultured; Feces; Female; Humans; Immunoglobulin A; Infant; Norovirus; Rotavirus; Saliva; Salivary Glands; Spheroids, Cellular; Virus Diseases; Viruses
PubMed: 35768512
DOI: 10.1038/s41586-022-04895-8 -
Viruses Jun 2021Astrovirus infections are among the main causes of diarrhea in children, but their significance for animal health has remained underestimated and largely unknown. This... (Review)
Review
Astrovirus infections are among the main causes of diarrhea in children, but their significance for animal health has remained underestimated and largely unknown. This is changing due to the increasing amount of newly identified neurotropic astroviruses in cases of nonsuppurative encephalitis and neurological disease in humans, pigs, ruminant species and minks. Neurological cases in ruminants and humans usually occur sporadically and as isolated cases. This contrasts with the situation in pigs and minks, in which diseases associated with neurotropic astroviruses are endemic and occur on the herd level. Affected animals show neurological signs such as mild ataxia to tetraplegia, loss of orientation or trembling, and the outcome is often fatal. Non-suppurative inflammation with perivascular cuffing, gliosis and neuronal necrosis are typical histological lesions of astrovirus encephalitis. Since astroviruses primarily target the gastrointestinal tract, it is assumed that they infect the brain through the circulatory system or retrograde following the nerves. The phylogenetic analysis of neurotropic astroviruses has revealed that they are genetically closely related, suggesting the presence of viral determinants for tissue tropism and neuroinvasion. In this review, we summarize the current knowledge on neurotropic astrovirus infections in animals and propose future research activities.
Topics: Animals; Astroviridae; Astroviridae Infections; Brain; Encephalitis, Viral; Genome, Viral; Nervous System Diseases; Phylogeny
PubMed: 34201545
DOI: 10.3390/v13071201 -
Current Opinion in Virology Aug 2019Although astroviruses are most commonly associated with acute gastrointestinal illness in humans, their ability to infect a broad range of hosts and cause a spectrum of... (Review)
Review
Although astroviruses are most commonly associated with acute gastrointestinal illness in humans, their ability to infect a broad range of hosts and cause a spectrum of disease makes them widespread and complex pathogens. The precise mechanisms that dictate the course of astrovirus disease have not been studied extensively but are likely driven by multifactorial host-microbe interactions. Recent insights from studies of animal astrovirus infections have revealed both beneficial and detrimental effects for the host. However, further in-depth studies are needed to fully explore the consequences of astrovirus-induced changes in the gut microenvironment as well as the role of the microbiota in astrovirus infection.
Topics: Animals; Astroviridae; Astroviridae Infections; Birds; Chiroptera; Gastroenteritis; Gastrointestinal Microbiome; Host Microbial Interactions; Humans; Mamastrovirus; Mice; Microbial Interactions; RNA Viruses
PubMed: 31163291
DOI: 10.1016/j.coviro.2019.05.002 -
Viruses Jun 2022Bovine astrovirus (BoAstV) is a small non-enveloped virus with a single-stranded positive-sense RNA. In 1978, BoAstV was first found in calf diarrhea fecal samples in... (Review)
Review
Bovine astrovirus (BoAstV) is a small non-enveloped virus with a single-stranded positive-sense RNA. In 1978, BoAstV was first found in calf diarrhea fecal samples in the United Kingdom and since then it has been reported in many other countries. It has wide tissue tropism and can infect multiple organs, including the intestine, nerves and respiratory tract. Since BoAstV is prevalent in healthy as well as clinically infected bovines, and is mostly associated with co-infection with other viruses, the pathogenic nature of BoAstV is still unclear. At present, there are no stable passage cell lines available for the study of BoAstV and animal model experiments have not been described. In addition, it has been reported that BoAstV may have the possibility of cross-species transmission. This review summarizes the current state of knowledge about BoAstV, including the epidemiology, evolution analysis, detection methods, pathogenesis and potential cross species transmission, to provide reference for further research of BoAstV.
Topics: Animals; Astroviridae Infections; Cattle; Cattle Diseases; Feces; Kobuvirus
PubMed: 35746688
DOI: 10.3390/v14061217 -
Viruses Jun 2021Astroviruses are non-enveloped, single-stranded RNA viruses that infect mammalian and avian species. In humans, astrovirus infections are one of the most common causes... (Review)
Review
Astroviruses are non-enveloped, single-stranded RNA viruses that infect mammalian and avian species. In humans, astrovirus infections are one of the most common causes of gastroenteritis in children. Infection has also been linked to serious neurological complications, especially in immunocompromised individuals. More extensive disease has also been characterized in non-human mammalian and avian species. To date, astroviruses have been detected in over 80 different avian and mammalian hosts. As the number of hosts continues to rise, the need to understand how astroviruses transmit within a given species as well as to new host species becomes increasingly important. Here, we review the current understanding of astrovirus transmission, the factors that influence viral spread, and the potential for cross-species transmission. Additionally, we highlight the current gaps in knowledge and areas of future research that will be key to understanding astrovirus transmission and zoonotic potential.
Topics: Animals; Astroviridae; Astroviridae Infections; Birds; Gastroenteritis; Host Specificity; Humans; Phylogeny; Viral Zoonoses
PubMed: 34208242
DOI: 10.3390/v13061127 -
The Journal of General Virology Mar 2021A long-standing paradigm in virology was that non-enveloped viruses induce cell lysis to release progeny virions. However, emerging evidence indicates that some... (Review)
Review
A long-standing paradigm in virology was that non-enveloped viruses induce cell lysis to release progeny virions. However, emerging evidence indicates that some non-enveloped viruses exit cells without inducing cell lysis, while others engage both lytic and non-lytic egress mechanisms. Enteric viruses are transmitted via the faecal-oral route and are important causes of a wide range of human infections, both gastrointestinal and extra-intestinal. Virus cellular egress, when fully understood, may be a relevant target for antiviral therapies, which could minimize the public health impact of these infections. In this review, we outline lytic and non-lytic cell egress mechanisms of non-enveloped enteric RNA viruses belonging to five families: , , , and . We discuss factors that contribute to egress mechanisms and the relevance of these mechanisms to virion stability, infectivity and transmission. Since most data were obtained in traditional two-dimensional cell cultures, we will further attempt to place them into the context of polarized cultures and pathogenesis. Throughout the review, we highlight numerous knowledge gaps to stimulate future research into the egress mechanisms of these highly prevalent but largely understudied viruses.
Topics: Animals; Humans; RNA Virus Infections; RNA Viruses; Virion; Virus Release
PubMed: 33560198
DOI: 10.1099/jgv.0.001557 -
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 -
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 -
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 -
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