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4369 KiB

Open AccessArticle

Frequency and Pathological Phenotype of Bovine Astrovirus CH13/NeuroS1 Infection in Neurologically-Diseased Cattle: Towards Assessment of Causality

by Senija Selimovic-Hamza, Céline L. Boujon, Monika Hilbe, Anna Oevermann and Torsten Seuberlich

Viruses 2017, 9(1), 12; https://doi.org/10.3390/v9010012 - 18 Jan 2017

Cited by 34 | Viewed by 7456

Abstract

Next-generation sequencing (NGS) has opened up the possibility of detecting new viruses in unresolved diseases. Recently, astrovirus brain infections have been identified in neurologically diseased humans and animals by NGS, among them bovine astrovirus (BoAstV) CH13/NeuroS1, which has been found in brain tissues [...] Read more.

Next-generation sequencing (NGS) has opened up the possibility of detecting new viruses in unresolved diseases. Recently, astrovirus brain infections have been identified in neurologically diseased humans and animals by NGS, among them bovine astrovirus (BoAstV) CH13/NeuroS1, which has been found in brain tissues of cattle with non-suppurative encephalitis. Only a few studies are available on neurotropic astroviruses and a causal relationship between BoAstV CH13/NeuroS1 infections and neurological disease has been postulated, but remains unproven. Aiming at making a step forward towards assessing the causality, we collected brain samples of 97 cases of cattle diagnosed with unresolved non-suppurative encephalitis, and analyzed them by in situ hybridization and immunohistochemistry, to determine the frequency and neuropathological distribution of the BoAstV CH13/NeuroS1 and its topographical correlation to the pathology. We detected BoAstV CH13/NeuroS1 RNA or proteins in neurons throughout all parts of the central nervous system (CNS) in 34% of all cases, but none were detected in cattle of the control group. In general, brain lesions had a high correlation with the presence of the virus. These findings show that a substantial proportion of cattle with non-suppurative encephalitis are infected with BoAstV CH13/NeuroS1 and further substantiate the causal relationship between neurological disease and astrovirus infections. Full article

(This article belongs to the Special Issue Astroviruses)

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Review

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678 KiB

Open AccessReview

Viral Encephalitis of Unknown Cause: Current Perspective and Recent Advances

by Peter G. E. Kennedy, Phenix-Lan Quan and W. Ian Lipkin

Viruses 2017, 9(6), 138; https://doi.org/10.3390/v9060138 - 6 Jun 2017

Cited by 59 | Viewed by 9108

Abstract

Viral encephalitis causes acute inflammation of the brain parenchyma and is a significant cause of human morbidity and mortality. Although Herpes Simplex encephalitis is the most frequent known cause of fatal sporadic encephalitis in humans, an increasingly wide range of viruses and other [...] Read more.

Viral encephalitis causes acute inflammation of the brain parenchyma and is a significant cause of human morbidity and mortality. Although Herpes Simplex encephalitis is the most frequent known cause of fatal sporadic encephalitis in humans, an increasingly wide range of viruses and other microbial pathogens are implicated. Up to 60% of cases of presumed viral encephalitis remain unexplained due to the failure of conventional laboratory techniques to detect an infectious agent. High-throughput DNA sequencing technologies have the potential to detect any microbial nucleic acid present in a biological specimen without any prior knowledge of the target sequence. While there remain challenges intrinsic to these technologies, they have great promise in virus discovery in unexplained encephalitis. Full article

(This article belongs to the Special Issue Astroviruses)

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1234 KiB

Open AccessReview

The Broad Host Range and Genetic Diversity of Mammalian and Avian Astroviruses

by Celeste Donato and Dhanasekaran Vijaykrishna

Viruses 2017, 9(5), 102; https://doi.org/10.3390/v9050102 - 10 May 2017

Cited by 125 | Viewed by 9829

Abstract

Astroviruses are a diverse family of viruses that infect a wide range of mammalian and avian hosts. Here we describe the phylogenetic diversity and current classification methodology of astroviruses based on the ORF1b and ORF2 genes, highlighting the propensity of astroviruses to undergo [...] Read more.

Astroviruses are a diverse family of viruses that infect a wide range of mammalian and avian hosts. Here we describe the phylogenetic diversity and current classification methodology of astroviruses based on the ORF1b and ORF2 genes, highlighting the propensity of astroviruses to undergo interspecies transmission and genetic recombination which greatly increase diversity and complicate attempts at a unified and comprehensive classification strategy. Full article

(This article belongs to the Special Issue Astroviruses)

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682 KiB

Open AccessReview

Bat Astroviruses: Towards Understanding the Transmission Dynamics of a Neglected Virus Family

by Kerstin Fischer, Vinícius Pinho dos Reis and Anne Balkema-Buschmann

Viruses 2017, 9(2), 34; https://doi.org/10.3390/v9020034 - 21 Feb 2017

Cited by 32 | Viewed by 6754

Abstract

Bats belong to the order Chiroptera that represents the second largest order of mammals with more than 1200 species and an almost global distribution. Environmental changes and deforestation have severely influenced many ecosystems, intensifying the contact between wildlife and humans. In recent years, [...] Read more.

Bats belong to the order Chiroptera that represents the second largest order of mammals with more than 1200 species and an almost global distribution. Environmental changes and deforestation have severely influenced many ecosystems, intensifying the contact between wildlife and humans. In recent years, bats have been found to harbor a number of different viruses with zoonotic potential, as well as a great diversity of astroviruses, for which the question of zoonotic potential remains unanswered to date. Human astroviruses have been identified as the causative agent for diarrhea in children and immunocompromised patients. For a long time, astroviruses have been considered to be strictly species-specific. However, a great genetic diversity has recently been discovered among animal and human astroviruses that might indicate the potential of these viruses to cross species barriers. Furthermore, our knowledge about the tissue tropism of astroviruses has been expanded to some neurotropic strains that have recently been shown to be responsible for encephalitis in humans and livestock. This review gives an overview on what is known about astroviruses in bats, humans and livestock, especially bovines and pigs. Future research activities are suggested to unravel astrovirus infection dynamics in bat populations to further assess the zoonotic potential of these viruses. Full article

(This article belongs to the Special Issue Astroviruses)

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2599 KiB

Open AccessReview

Epidemiology of Classic and Novel Human Astrovirus: Gastroenteritis and Beyond

by Diem-Lan Vu, Albert Bosch, Rosa M. Pintó and Susana Guix

Viruses 2017, 9(2), 33; https://doi.org/10.3390/v9020033 - 18 Feb 2017

Cited by 140 | Viewed by 12410

Abstract

Since they were identified in 1975, human astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent astroviruses infecting humans have been recently discovered and associated with extra-intestinal infections. The report of cases of [...] Read more.

Since they were identified in 1975, human astroviruses have been considered one of the most important agents of viral acute gastroenteritis in children. However, highly divergent astroviruses infecting humans have been recently discovered and associated with extra-intestinal infections. The report of cases of fatal meningitis and encephalitis, especially in immunocompromised individuals, has broadened their disease spectrum. Although zoonotic transmission among animal and human astroviruses has not been clearly recognized, the genetic similarity between some human and animal viruses makes it likely to occur. This review provides an update on the epidemiology of both classic and novel human astroviruses, and a comprehensive view on confirmed or potential association between astrovirus and human disease. Full article

(This article belongs to the Special Issue Astroviruses)

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548 KiB

Open AccessReview

A Review of the Strain Diversity and Pathogenesis of Chicken Astrovirus

by Victoria J. Smyth

Viruses 2017, 9(2), 29; https://doi.org/10.3390/v9020029 - 10 Feb 2017

Cited by 57 | Viewed by 7354

Abstract

Although a relatively recently emerged virus, identified only in 2004 as a separate species of avian astrovirus, chicken astrovirus (CAstV) has been associated with poor growth of broiler flocks, enteritis and diarrhea and is a candidate pathogen in cases of runting stunting syndrome. [...] Read more.

Although a relatively recently emerged virus, identified only in 2004 as a separate species of avian astrovirus, chicken astrovirus (CAstV) has been associated with poor growth of broiler flocks, enteritis and diarrhea and is a candidate pathogen in cases of runting stunting syndrome. More recently CAstV has been implicated in cases of two other diseases of broilers as the sole etiological agent, namely severe kidney disease of young broilers with visceral gout and the “White Chicks” hatchery disease. Examination of the strains of CAstV associated with the two latter diseases reveals they are closely related genetically. This review will discuss the pathogenesis of CAstV in relation to strain diversity and the effects of vertical versus horizontal transmission, virus load, co-infections and age of bird at infection, all factors that may impact upon disease severity. Full article

(This article belongs to the Special Issue Astroviruses)

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991 KiB

Open AccessReview

Astrovirus Pathogenesis

by Cydney Johnson, Virginia Hargest, Valerie Cortez, Victoria A. Meliopoulos and Stacey Schultz-Cherry

Viruses 2017, 9(1), 22; https://doi.org/10.3390/v9010022 - 22 Jan 2017

Cited by 79 | Viewed by 13523

Abstract

Astroviruses are a major cause of diarrhea in the young, elderly, and the immunocompromised. Since the discovery of human astrovirus type 1 (HAstV-1) in 1975, the family Astroviridae has expanded to include two more human clades and numerous mammalian and avian-specific genotypes. Despite [...] Read more.

Astroviruses are a major cause of diarrhea in the young, elderly, and the immunocompromised. Since the discovery of human astrovirus type 1 (HAstV-1) in 1975, the family Astroviridae has expanded to include two more human clades and numerous mammalian and avian-specific genotypes. Despite this, there is still little known about pathogenesis. The following review highlights the current knowledge of astrovirus pathogenesis, and outlines the critical steps needed to further astrovirus research, including the development of animal models of cell culture systems. Full article

(This article belongs to the Special Issue Astroviruses)

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1158 KiB

Open AccessReview

The Astrovirus Capsid: A Review

by Carlos F. Arias and Rebecca M. DuBois

Viruses 2017, 9(1), 15; https://doi.org/10.3390/v9010015 - 19 Jan 2017

Cited by 92 | Viewed by 15162

Abstract

Astroviruses are enterically transmitted viruses that cause infections in mammalian and avian species. Astroviruses are nonenveloped, icosahedral viruses comprised of a capsid protein shell and a positive-sense, single-stranded RNA genome. The capsid protein undergoes dramatic proteolytic processing both inside and outside of the [...] Read more.

Astroviruses are enterically transmitted viruses that cause infections in mammalian and avian species. Astroviruses are nonenveloped, icosahedral viruses comprised of a capsid protein shell and a positive-sense, single-stranded RNA genome. The capsid protein undergoes dramatic proteolytic processing both inside and outside of the host cell, resulting in a coordinated maturation process that affects cellular localization, virus structure, and infectivity. After maturation, the capsid protein controls the initial phases of virus infection, including virus attachment, endocytosis, and genome release into the host cell. The astrovirus capsid is the target of host antibodies including virus-neutralizing antibodies. The capsid protein also mediates the binding of host complement proteins and inhibits complement activation. Here, we will review our knowledge on the astrovirus capsid protein (CP), with particular attention to the recent structural, biochemical, and virological studies that have advanced our understanding of the astrovirus life cycle. Full article

(This article belongs to the Special Issue Astroviruses)

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335 KiB

Open AccessReview

Astrovirus Diagnostics

by Philippe Pérot, Marc Lecuit and Marc Eloit

Viruses 2017, 9(1), 10; https://doi.org/10.3390/v9010010 - 12 Jan 2017

Cited by 36 | Viewed by 8480

Abstract

Various methods exist to detect an astrovirus infection. Current methods include electron microscopy (EM), cell culture, immunoassays, polymerase chain reaction (PCR) and various other molecular approaches that can be applied in the context of diagnostic or in surveillance studies. With the advent of [...] Read more.

Various methods exist to detect an astrovirus infection. Current methods include electron microscopy (EM), cell culture, immunoassays, polymerase chain reaction (PCR) and various other molecular approaches that can be applied in the context of diagnostic or in surveillance studies. With the advent of metagenomics, novel human astrovirus (HAstV) strains have been found in immunocompromised individuals in association with central nervous system (CNS) infections. This work reviews the past and current methods for astrovirus detection and their uses in both research laboratories and for medical diagnostic purposes. Full article

(This article belongs to the Special Issue Astroviruses)

385 KiB

Open AccessReview

The Immune Response to Astrovirus Infection

by Shauna A. Marvin

Viruses 2017, 9(1), 1; https://doi.org/10.3390/v9010001 - 30 Dec 2016

Cited by 9 | Viewed by 6003

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Astroviruses)

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