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A novel goose astrovirus (GAstV) has broken out across China in recent years, causing widespread damage to the poultry industry. In goslings infected with GAstV, the leading cause of death is visceral gout. However, our understanding of the mechanism of gout formation in GAstV infection is largely inadequate. The aim of this study was to examine the pathogenicity of a GAstV strain and explore the molecular mechanisms of visceral gout caused by viral infection in goslings. The virulent GAstV strain HR2105/1 was effectively isolated from the visceral tissue of goslings in gout-affected areas. The whole genome of the HR2105/1 strain was sequenced and analyzed. Subsequently, we established a gosling gout models with experimental GAstV infection. Finally, we conducted a study on the mechanism of GAstV induced acute kidney injury. Phylogenetic analysis of the complete genome sequence showed that it was closely related to the strain circulating in China since 2016, and it was grouped within the GAstV-1 cluster. The clinical signs were reproduced by experimental infection of healthy goslings with the isolated strain and were found to be similar to those reported in clinical cases. Moreover, the virus exhibits strong renal tropism. Infection with the GAstV strain HR2105/1 was found to cause acute kidney injury, as evidenced by increased levels of uric acid and creatinine as well as severe pathological damage. Mechanistic experiments with Masson and Picrosirius Red staining revealed fibrosis in renal tissues after GAstV infection. Furthermore, TUNEL staining revealed that GAstV infection triggered renal cell apoptosis. Additionally, RT-qPCR revealed that GAstV infection caused an excessive inflammatory response by upregulating the expression of IL-1β, IL-6, IL-10, TGF-β, and iNOS in renal tissues. Overall, our findings demonstrate that GAstV infection causes renal damage by inducing renal cell apoptosis, fibrosis, and excessive inflammatory response, which subsequently leads to hyperuricemia and lethal visceral gout formation. This is the first systematic study on the etiology of lethal gout in goslings caused by GAstV infection, and we believe that the findings can guide vaccine development and therapeutic targets for GAstV-associated renal diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Bi, Lv, Zhang, Cai, Zhang, Li, Ding, Liu, Yang, Zhu, Liu and Wang.)

Goose astroviruses (GAstVs) are important pathogens which can cause gout in goslings leading to huge economic losses for the goose farming industry in China. In 2023, an infectious disease characterized by visceral gout broke out in commercial goose farms in Guangxi and Guangdong provinces of China. In this study, two GAstV strains of GXNN and GDCS were successfully isolated from these two disease-ridden goose farms. The complete genomic lengths of these two strains were 7166 bp, and phylogenetic analysis showed that they were both GAstV-2 subtypes. The 3-dimensional structures of the capsid protein were predicted and six characteristic mutation sites at amino acid positions 60, 61, 228, 229, 456 and 523 were found within the strong antigenic regions. A recombination event occurred at 6833-7070 nt between the GAstV TZ03 and Turkey astrovirus CA/00 and this was detected in both the GXNN and GDCS strains. Another recombinant event occurred at 63-2747 nt between the GAstV XT1 and GAstV SDPY and this was detected in the GDCS strain. When 1-day-old goslings were infected with the novel GXNN and GDCS strains, they showed severe visceral gout. This was accompanied by enlarged spleens, liver hemorrhages and urate deposits in the kidneys and ureters and their blood urea nitrogen levels were significantly elevated. The mortality rates of the GXNN- and GDCS-infected groups were pathogenically high at 80 % and 60 %, respectively. These results will promote our understanding of the evolution and epidemic potential of GAstVs in China., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Bats (order: Chiroptera) are known to host a diverse range of viruses, some of which present a human public health risk. Thorough viral surveillance is therefore essential to predict and potentially mitigate zoonotic spillover. Astroviruses (family: Astroviridae) are an understudied group of viruses with a growing amount of indirect evidence for zoonotic transfer. Astroviruses have been detected in bats with significant prevalence and diversity, suggesting that bats may act as important astrovirus hosts. Most astrovirus surveillance in wild bat hosts has, to date, been restricted to single-gene PCR detection and concomitant Sanger sequencing; additionally, many bat species and many geographic regions have not yet been surveyed for astroviruses at all. Here, we use metagenomic Next Generation Sequencing (mNGS) to detect astroviruses in three species of Madagascar fruit bats, Eidolon dupreanum, Pteropus rufus, and Rousettus madagascariensis. We detect numerous partial sequences from all three species and one near-full length astrovirus sequence from Rousettus madagascariensis, which we use to characterize the evolutionary history of astroviruses both within bats and the broader mammalian clade, Mamastrovirus. Taken together, applications of mNGS implicate bats as important astrovirus hosts and demonstrate novel patterns of bat astrovirus evolutionary history, particularly in the Southwest Indian Ocean region., (© 2024. The Author(s).)

Applying a pan-astrovirus (AstV) RT-hemi-nested PCR assay, we report here high detection rates (28.3%, 15/53) of AstVs in the small Indian mongoose ( Urva auropunctata ) on the Caribbean Island of St. Kitts. Based on deduced amino acid (aa) identities and phylogenetic analysis of long RNA-dependent RNA polymerase (RdRp) sequences (~315 aa, partial RdRp), the AstVs detected in the mongooses (designated as Mon-AstVs) were classified into two distinct groups (deduced aa identities of 66.45-67.30% between the groups). The putative RdRps of the Mon-AstVs shared low deduced aa identities with those of AstVs from other host species (<69%, <54%, and <50% identities with reptilian/amphibian AstVs, avastroviruses, and mamastroviruses, respectively). Phylogenetically, the group-I and group-II Mon-AstVs formed two distinct clusters, near the cluster of reptilian/amphibian AstVs, and were distantly related to avastroviruses and mamastroviruses. Since the mongooses were apparently healthy during sampling, we could not establish if the Mon-AstVs infected the animal or were of dietary origin. Although we could not ascertain the true host of the Mon-AstVs, phylogenetic analysis indicated that these viruses might have originated from lower vertebrates. To our knowledge, this is the first report on the detection and molecular characterization of AstVs in mongooses, highlighting the wide host range and significant genetic diversity within the family Astroviridae .

Introduction. Data on the frequency of enteric adenoviruses, sapoviruses, and astroviruses in cases of sporadic acute gastroenteritis in Argentina are scarce. Methods. Descriptive design of a selection of fecal samples of children with diarrhea younger than 5 years referred between 2010 and 2021, with a previous negative result for rotavirus and norovirus. The presence of enteric adenovirus, sapovirus, and astrovirus was tested by molecular methods, with subsequent genotyping of positive samples. Results. At least 1 of the tested viruses was detected in 226 (39.4%) of the 574 selected samples. Specifically, adenovirus, sapovirus, and astrovirus were detected in 30.7%, 5.6%, and 3.1% of the samples, respectively. The most frequent viruses detected were adenovirus 41, sapoviruses GI.1 and GI.2, and astrovirus 1. Non-classic astroviruses were detected in 2 samples. Conclusions. Despite being less frequent, these enteropathogens are responsible for a large number of sporadic diarrhea events. Therefore, their study and surveillance contribute significantly to reduce the gap of undiagnosed cases., (Sociedad Argentina de Pediatría.)

Caliciviruses (Caliciviridae) and astroviruses (Astroviridae) are among the leading cause of non-bacterial foodborne disease and gastroenteritis in human. These non-enveloped RNA viruses infect a wide range of vertebrate species including rodents. Rodents are among the most important hosts of infectious diseases globally and are responsible for over 80 zoonotic pathogens that affect humans. Therefore, screening pathogens in rodents will be is necessary to prevent cross-species transmission to prevent zoonotic outbreaks. In the present study, we screened caliciviruses and astroviruses in order to describe their diversity and whether they harbor strains that can infect humans. RNA was then extracted from intestine samples of 245 rodents and retrotranscribed in cDNA to screen caliciviruses and astroviruses by PCRs. All the samples tested negative for caliciviruses and while astroviruses were detected in 18 (7.3%) samples of Rattus rattus species. Phylogenetic analyses based on the RdRp gene showed that all the sequences belonged to Mamastrovirus genus in which they were genetically related to R. rattus related AstVs previously detected in Gabon or in Rattus spp. AstV from Kenya and Asia. These findings suggested that transportation such as land and railway, as well national and international trade, are likely to facilitate spread of AstVs by the dissemination of rodents., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Here, we report the results of a monitoring study of bat viruses in Austria to strengthen the knowledge of circulating viruses in Austrian bat populations. In this study, we analyzed 618 oropharyngeal and rectal swab samples from 309 bats and 155 pooled tissue samples from dead bats. Samples were collected from 18 different bat species from multiple locations in Austria, from November 2015 to April 2018, and examined for astroviruses, bornaviruses, coronaviruses, hantaviruses, morbilliviruses, orthomyxoviruses (influenza A/C/D viruses), pestiviruses and rhabdoviruses (lyssaviruses) using molecular techniques and sequencing. Using RT-qPCR, 36 samples revealed positive or suspicious results for astroviruses, Brno-hantaviruses, and coronaviruses in nine different bat species. Further sequencing revealed correspondent sequences in five samples. In contrast, none of the tested samples was positive for influenza viruses A/C/D, bornaviruses, morbilliviruses, lyssaviruses, or pestiviruses.

Astroviruses are single-stranded, positive-sense RNA viruses capable of infecting humans as well as a wide range of mammalian and avian species, with a length of approximately 6.6-7.7 kb. In this study, 139 goat fecal samples collected from the Guangxi province were used for the RT-PCR detection, and two of these were positive for goat astrovirus, with a positivity rate of 1.44% (2/139). The complete genome sequence of an astrovirus strain and the partial genome sequence of a strain astrovirus, named GX WZ 2023 and GX HC 2023, were amplified and sequenced, and their sequence lengths were 6284 nt and 6213 nt, respectively. Among them, the capsid protein of goat astrovirus GX HC 2023 showed the highest amino acid identity of 95.9% with ovine astrovirus GX, which belonged to the MAstV-2 genotype. However, the closest relative of the GX WZ 2023 strain was found to be the caprine astrovirus Sichuan, with a nucleotide sequence identity of 76.8%. The ORF1ab nonstructural protein of this strain showed the highest amino acid identities of 89.2 and 95.8% with the ovine astrovirus S5.1 and caprine astrovirus G5.1 strains, respectively. However, its ORF2 capsid protein has 68.4% amino acid identity with the bovine astrovirus (BAstV) 16 2021 CHN strain and only 21.9-64% amino acid identity with all available strains of goat astrovirus. The GX WZ 2023 strain was recombined with the Chinese (BAstV 16 2021 CHN) and Japanese bovine strains (BAstV JPN 2015) in the ORF2 region. Therefore, the goat astrovirus GX WZ 2023 is proposed as a new member of the family goat astroviridae based on the species classification criteria of the International Committee on Taxonomy of Viruses. These findings enhance our understanding of the prevalence and genetic evolution of goat astrovirus and provide a scientific basis for future studies of these viruses in other animals.

Wild waterfowl serve as a reservoir of some astroviruses. Fecal samples from wild waterfowl collected at Hong Kong's Marshes were tested using pan-astrovirus reverse transcription-PCR. Positive samples underwent subsequent host identification using DNA barcoding. Based on deduced partial sequences, noteworthy samples from three astrovirus groups (mammalian, avian and unclassified astroviruses) were further analyzed by next-generation sequencing. One sample of Avastrovirus 4 clade, MP22-196, had a nearly complete genome identified. The results of ORF2 phylogenetic analysis and genetic distance analysis indicate that Avastrovirus 4 is classified as a distinct subclade within Avastrovirus. MP22-196 has typical astrovirus genome characteristics. The unique characteristics and potential differences of this genome, compared to other avian astrovirus sequences, involve the identification of a modified sgRNA sequence situated near the ORF2 start codon, which precedes the ORF1b stop codon. Additionally, the 3' UTR of MP22-196 is shorter than other avian astroviruses. This study expands our understanding of the Avastrovirus 4 clade., (© 2024. The Author(s).)

Background: This study presents the case of non-purulent encephalomyelitis associated with astrovirus infection in a sheep from Eastern Anatolia, Türkiye., Methods: A necropsy was performed on a sheep showing nervous signs. Afterwards, brain tissue samples were taken and examined with histopathological, immunohistochemical and molecular techniques., Results: Neuropathologic changes included neuronal degeneration, diffuse gliosis, multifocal perivascular cuffing, neuronophagy and neuronal necrosis in the cerebrum, the cerebellum and the cervical spinal cord. Aerobic and anaerobic bacterial culture, selective culture for Listeria monocytogenes, and PCR analysis for rabies virus, tick-borne encephalitis virus, Türkiye encephalitis virus, small ruminant lentiviruses and border disease virus were negative. However, the presence of astrovirus RNA in cerebral, cerebellar and spinal cord samples was demonstrated by a pan-astrovirus RT-PCR. Immunohistochemical examinations revealed astrovirus antigens within the neuronal cytoplasm. High-throughput sequencing techniques identified the causative agent as a member of the genotype species Mamastrovirus 13 but representing a distinct genetic lineage with similarity to ovine astrovirus 1 in the open-reading frames (ORF)1ab region and muskox astrovirus in the ORF2 region., Conclusion: This report provides evidence that astroviruses are potentially encephalitis-causing pathogens in ovine populations in Türkiye, featuring an astrovirus strain distinct from those previously identified in sheep., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Small terrestrial mammals are major hosts of infectious agents responsible for zoonotic diseases. Astroviruses (AstVs)-the cause of non-bacterial gastroenteritis mainly affecting young children-have been detected in a wide array of mammalian and avian host species. However, understanding the factors that influence AstV infection within and across hosts is limited. Here, we investigated the impact of land use changes on AstVs in terrestrial small mammals in rural northeastern Madagascar. We sampled 515 small mammals, representing seven endemic and four introduced species. Twenty-two positive samples were identified, all but one of which were found in the introduced species Mus musculus and Rattus rattus (family Muridae), with a positivity rate of 7.7% (6/78) and 5.6% (15/266), respectively. The non-introduced rodent case was from an endemic shrew-tenrec (family Tenrecidae). We found the highest positivity rate of AstVs infection in brushy regrowth (17.5%, 7/40) as compared to flooded rice fields (4.60%, 8/174), secondary forest (4.1%, 3/74), agroforest (3.6%, 1/28), village (2.61%, 3/115), and semi-intact forest (0%, 0/84). A phylogenetic analysis revealed an association between AstVs and their rodent host species. None of the viruses were phylogenetically related to AstVs previously described in Malagasy bats. This study supports AstV circulation in synanthropic animals in agricultural habitats of Madagascar and highlights the need to assess the spillover risk to human populations in rural areas., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Carcauzon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

(1) Goose astrovirus (GAstV) is a novel emerging pathogen that causes significant economic losses in waterfowl farming. A convenient, sensitive, and specific detection method for GAstV in field samples is important in order to effectively control GAstV. Droplet digital polymerase chain reaction (ddPCR) is a novel, sensitive, good-precision, and absolute quantitation PCR technology which does not require calibration curves. (2) In this study, we developed a ddPCR system for the sensitive and accurate quantification of GAstV using the conserved region of the ORF2 gene. (3) The detection limit of ddPCR was 10 copies/µL, ~28 times greater sensitivity than quantitative real-time PCR (qPCR). The specificity of the test was determined by the failure of amplification of other avian viruses. Both ddPCR and qPCR tests showed good repeatability and linearity, and the established ddPCR method had high sensitivity and good specificity to GAstV. Clinical sample test results showed that the positive rate of ddPCR (88.89%) was higher than that of qPCR (58.33%). (4) As a result, our results suggest that the newly developed ddPCR method might offer improved analytical sensitivity and specificity in its GAstV measurements. The ddPCR could be widely applied in clinical tests for GAstV infections.

Astroviruses have been found in cattle and other species with encephalitis. Our objective was to determine the frequency of neurotropic bovine astrovirus (BoAstV) in cases of encephalitis in cattle ≥ 4-mo-old. Of 56 cases of idiopathic lymphocytic encephalitis examined retrospectively (1988-2019), fixed brain from 11 cases (19%) tested positive by semi-quantitative RT-PCR for BoAstV CH13/NeuroS1. None of the control cases tested positive, including 32 with other forms of encephalitis and 40 with no neurologic disease. Most astrovirus-positive cases were 1-2-y-old, with a range of 7 mo to 7 y, and affected both beef and dairy breeds with wide geographic distribution. BoAstV-positive cases had acute onset of neurologic signs of 12 h to 7 d before death or euthanasia. Affected cattle had lymphocytic inflammation throughout the brain including cerebrum, thalamus, midbrain, cerebellum, medulla oblongata, and spinal cord, and affecting gray and white matter. Further PCR testing identified a possible cause in 9 of the 45 (20%) remaining idiopathic cases of lymphocytic encephalitis, including eastern equine encephalitis virus, Listeria monocytogenes , bovine viral diarrhea virus, bovine alphaherpesvirus 1, and ovine gammaherpesvirus 2 (malignant catarrhal fever); we found no cases of infection by West Nile virus, rabies virus, or Chlamydia spp. No cause was identified in 36 of 56 (64%) cases of lymphocytic encephalitis. We frequently identified neurotropic BoAstV in cases of lymphocytic encephalitis that had no previously identified cause. Neurotropic BoAstV infections had gone undetected for decades, but the frequency of BoAstV infections has not increased among contemporary cases., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Goose astrovirus genotype 1 (GAstV-1) has emerged in goose farms in some provinces of China in recent years and is considered to be one of the pathogens of gout in goslings in China. However, few studies have been conducted on the dynamic distribution, tissue tropism, and pathogenesis of GAstV-1 in goslings. In 2022, an epidemiological investigation of goose astrovirus (GAstV) in goslings was conducted in seven provinces of China. During the investigation, a GAstV-1 designated as GAstV-JSXZ was identified in the kidney of an 8-day-old gosling and was successfully isolated from a goose embryo. The full genome sequence of GAstV-JSXZ was determined using the next-generation sequencing technique. The complete genome of GAstV-JSXZ was 7299-nt-long. Interestingly, the phylogenetic analysis revealed that Chinese GAstV-1 has formed two distinct subgroups based on the ORF 2 genomes, designated GAstV-1 1a and GAstV-1 1b. The GAstV-JSXZ shared the highest identity with GAstV-1 1a strain FLX and TZ03 in nucleotides (ORF1a: 98.3-98.4%; ORF1b: 92.3-99.1%; ORF2: 95.8-98.8%) and amino acid sequences (ORF1a: 99.4-99.5%; ORF1b: 98.2-98.8%; ORF2: 97.0-99.4%). To evaluate the pathogenicity of GAstV-1, 1-day-old goslings were inoculated with the virus by oral and subcutaneous injection routes, respectively. The results revealed that the virus causes extensive pathological organ damage, especially in the kidney, liver, and thymus. Virus-specific genomic RNA could be detected in the cloacal swabs and tissues of infected goslings throughout the experiment. The viral copy numbers examined in the kidney and intestine were the highest, followed by the liver and spleen. These results are likely to provide a new understanding of the pathogenicity of GAstV-1 in geese.

A commercial pig farm with no history of porcine circovirus 2 (PCV2) or porcine reproductive and respiratory syndrome virus (PRRSV) repeatedly reported a significant reduction in body weight gain and wasting symptoms in approximately 20-30% of the pigs in the period between three and six weeks after weaning. As standard clinical interventions failed to tackle symptomatology, viral metagenomics were used to describe and monitor the enteric virome at birth, 3 weeks, 4 weeks, 6 weeks, and 9 weeks of age. The latter four sampling points were 7 days, 3 weeks, and 6 weeks post weaning, respectively. Fourteen distinct enteric viruses were identified within the herd, which all have previously been linked to enteric diseases. Here we show that wasting is associated with alterations in the enteric virome of the pigs, characterized by: (1) the presence of enterovirus G at 3 weeks of age, followed by a higher prevalence of the virus in wasting pigs at 6 weeks after weaning; (2) rotaviruses at 3 weeks of age; and (3) porcine sapovirus one week after weaning. However, the data do not provide a causal link between specific viral infections and the postweaning clinical problems on the farm. Together, our results offer evidence that disturbances in the enteric virome at the preweaning stage and early after weaning have a determining role in the development of intestinal barrier dysfunctions and nutrient uptake in the postweaning growth phase. Moreover, we show that the enteric viral load sharply increases in the week after weaning in both healthy and wasting pigs. This study is also the first to report the dynamics and co-infection of porcine rotavirus species and porcine astrovirus genetic lineages during the first 9 weeks of the life of domestic pigs.

In this study, a total of 143 fecal samples (107 diarrheic and 36 non-diarrheic) were collected from 11 goat farms in southwest China, and 3.7% of diarrheic and 8.3% of non-diarrheic samples were detected as astrovirus-positive by RT-PCR. A nearly complete astrovirus genomic sequence (SWUN/F4/2019) of 6278 nucleotides (nt), which contained a 6186 bp open reading frame, was successfully obtained. The genome of strain SWUN/F4/2019 shared the highest nt identity (77.0%) and the closest genetic relationship with CapAstV-G5.1. It is worth noting that in the nonstructural protein 1ab, strain SWUN/F4/2019 shared the highest amino acid (aa) identity (93.8%) with strain CapAstV-G5.1; however, its capsid protein shared the highest aa identity (72.7%) with the Sichuan takin astrovirus strain LLT03 and only shared 23.1-64.8% aa identities with all available ovine and caprine astrovirus strains. Interestingly, a region recombination event was predicted in the ORF2 gene of strain SWUN/F4/2019, with CapAstV-G5.1 as the putative major parental strain and CcAstV/roe&#95;deer/SLO/D5-14/2014 as the possible minor parental strain. According to the species classification criteria of the International Committee on Taxonomy of Viruses (ICTV), SWUN/F4/2019 may represent a novel astrovirus in goats. To our knowledge, this is the first detection of astrovirus in goats in China and a novel astrovirus strain was identified in goats. These findings increase the understanding of the epidemic and the genetic evolution of astroviruses., (Copyright © 2021. Published by Elsevier B.V.)

Background: Enteritis of an infectious origin is a major cause of productivity and economic losses to cattle producers worldwide. Several pathogens are believed to cause or contribute to the development of calf diarrhea. Astroviruses (AstVs) are neglected enteric pathogens in ruminants, but they have recently gained attention because of their possible association with encephalitis in humans and various animal species, including cattle., Objectives: This paper describes a large outbreak of neonatal diarrhea in buffalo calves ( Bubalus bubalis ), characterized by high mortality, which was associated with an AstV infection., Methods: Following an enteritis outbreak characterized by high morbidity (100%) and mortality (46.2%) in a herd of Mediterranean buffaloes ( B. bubalis ) in Italy, 16 samples from buffalo calves were tested with the molecular tools for common and uncommon enteric pathogens, including AstV, kobuvirus, and torovirus., Results: The samples tested negative for common enteric viral agents, including Rotavirus A, coronavirus, calicivirus, pestivirus, kobuvirus, and torovirus, while they tested positive for AstV. Overall, 62.5% (10/16) of the samples were positive in a single round reverse transcription polymerase chain reaction (PCR) assay for AstV, and 100% (16/16) were positive when nested PCR was performed. The strains identified in the outbreak showed a clonal origin and shared the closest genetic relationship with bovine AstVs (up to 85% amino acid identity in the capsid)., Conclusions: This report indicates that AstVs should be included in a differential diagnosis of infectious diarrhea in buffalo calves., Competing Interests: The authors declare no conflicts of interest., (© 2021 The Korean Society of Veterinary Science.)

Rodents including rats are reservoir of several pathogens capable of affecting human health. In this study, faecal and different organ specimens from free-living Norway rats (Rattus norvegicus) (N = 18) and faecal samples from laboratory rodents (rats N = 21 and mice N = 20) collected from different geographic areas in Hungary between 2017 and 2020 were investigated by viral metagenomics and conventional RT-PCR methods. The complete genome of three different RNA viruses, rat astrovirus, rat norovirus and rat hepevirus were characterized and analysed in detail. Rat norovirus was detected in faecal (17.6%, 3/17) and kidney (7.1%, 1/14) samples; rat astrovirus in faecal (23.5%, 4/17) and spleen (13.3%, 2/15) samples, and rat hepevirus in 43% to 67% the faecal, liver, kidney, lung, heart, muscle, brain and blood samples from Norway rats, respectively. Rat norovirus was also identifiable in 5% (1/21) of laboratory rats and rat astrovirus in 40% (8/20) of faecal samples from laboratory mice. Co-infections were found in 28% (5/18) wild Norway rats. The highest RNA viral load of astrovirus (1.81 × 10 8 copy/g) and norovirus (3.49 × 10 7 copy/g) were measured in faecal samples; while the highest RNA viral load of hepevirus (1.16 × 10 9 copy/g) was found in liver samples of Norway rats, respectively. This study confirms the wide geographic distribution and high prevalence of astrovirus, norovirus and hepevirus among wild rats in Hungary with confirmation of different organ involvement of as well as the detection of norovirus and astrovirus in laboratory rats and mice, respectively. This finding further strengthens the role of rodents in the spread of viral pathogens especially infecting human., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Astroviruses (AstVs) are RNA viruses infecting a large diversity of avian and mammalian species, including bats, livestock, and humans. We investigated AstV infection in a free-tailed bat species, Mormopterus francoismoutoui , endemic to Reunion Island. A total of 380 guano samples were collected in a maternity colony during 38 different sampling sessions, from 21 June 2016 to 4 September 2018. Each sample was tested for the presence of the AstV RNA-dependent RNA-polymerase (RdRp) gene using a pan-AstV semi-nested polymerase chain reaction assay. In total, 27 guano samples (7.1%) tested positive, with high genetic diversity of the partial RdRp gene sequences among positive samples. Phylogenetic analysis further revealed that the detected viruses were genetically related to AstVs reported in rats, reptiles, dogs, and pigs, but did not cluster with AstVs commonly found in bats. Although more investigations need to be conducted to assess the prevalence of infected bats in the studied population, our findings show that Reunion free-tailed bats are exposed to AstVs, and suggest that cross-species transmission may occur with other hosts sharing the same habitat.

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.

Bat species worldwide are receiving increased attention for the discovery of emerging viruses, cross-species transmission, and zoonoses, as well as for characterizing virus infections specific to bats. In a previous study, we investigated the presence of coronaviruses in faecal samples from bats at different locations in Denmark, and made phylogenies based on short, partial ORF1b sequences. In this study, selected samples containing bat coronaviruses from three different bat species were analysed, using a non-targeted approach of next-generation sequencing. From the resulting metagenomics data, we assembled full-genome sequences of seven distinct alphacoronaviruses, three astroviruses, and a polyomavirus, as well as partial genome sequences of rotavirus H and caliciviruses, from the different bat species. Comparisons to published sequences indicate that the bat alphacoronaviruses belong to three different subgenera-i.e., Pedacovirus , Nyctacovirus , and Myotacovirus -that the astroviruses may be new species in the genus Mamastrovirus , and that the polyomavirus could also be a new species, but unassigned to a genus. Furthermore, several viruses of invertebrates-including two Rhopalosiphum padi (aphid) viruses and a Kadipiro virus-present in the faecal material were assembled. Interestingly, this is the first detection in Europe of a Kadipiro virus.

Neonatal calf diarrhea (NCD) and mortality cause significant losses to the dairy industry. The preweaning dairy calf mortality risk in Uruguay is high (15.2%); however, causes for these losses are largely unknown. This study aimed to assess whether various pathogens were associated with NCD and death in Uruguayan dairy calves and whether these infections, diarrhea, or deaths were associated with the failure of transfer of passive immunity (FTPI). Contemporary diarrheic (n = 264,) and non-diarrheic (n = 271) 1- to 30-day-old calves from 27 farms were sampled. Feces were analyzed by antigen-capture ELISA for Cryptosporidium spp., rotavirus, bovine coronavirus, and Escherichia coli F5+, RT-PCR for bovine astrovirus (BoAstV), and bacterial cultures for Salmonella enterica. Blood/serum was analyzed by RT-PCR or antigen-capture ELISA for bovine viral diarrhea virus (BVDV). Serum of ≤ 8-day-old calves (n = 95) was assessed by refractometry to determine the concention of serum total proteins (STP) as an indicator of FTPI. Whether the sampled calves died before weaning was recorded. At least one pathogen was detected in 65.4% of the calves, and this percentage was significantly higher in diarrheic (83.7%) versus non-diarrheic (47.6%) calves. Unlike the other pathogens, Cryptosporidium spp. and rotavirus were associated with NCD. Diarrheic calves, calves infected with any of the pathogens, and calves infected with rotavirus had significantly lower concentrations of STP. Diarrheic calves had higher chances of dying before weaning than non-diarrheic calves. Diarrheic calves infected with S. enterica were at increased risk of mortality. Controlling NCD, salmonellosis, cryptosporidiosis, and rotavirus infections, and improving colostrum management practices would help to reduce calf morbi-mortality in dairy farms in Uruguay.

Mink astrovirus infection remains a poorly understood disease entity, and the aetiological agent itself causes disease with a heterogeneous course, including gastrointestinal and neurological symptoms. This paper presents cases of astrovirus infection in mink from continental Europe. RNA was isolated from the brains and intestines of animals showing symptoms typical of shaking mink syndrome (n = 6). RT-PCR was used to amplify astrovirus genetic material, and the reaction products were separated on a 1% agarose gel. The specificity of the reaction was confirmed by sequencing fragment coding RdRP protein (length of sequencing product 170 bp) from all samples. The presence of astrovirus RNA was detected in each of the samples tested. Sequencing and bioinformatic analysis indicated the presence of the same variant of the virus in all samples. Comparison of the variant with the sequences available in bioinformatics databases confirmed that the Polish isolates form a separate clade, closely related to Danish isolates. The dissimilarity of the Polish variant to those isolated in other countries ranged from 2.4% (in relation to Danish isolates) to 7.1% (in relation to Canadian isolates). Phylogenetic relationships between variants appear to be associated with the geographic distances between them. To our knowledge, this work describes the first results on the molecular epidemiology of MAstV in continental Europe. The detection of MAstV in Central Europe indicates the need for further research to broaden our understanding of the molecular epidemiology of MAstV in Europe.

Diarrhea in mink kits is a major cause of disease and mortality in the mink production. The etiology remains unknown in most outbreaks due to a lack of diagnostic assays. In the current study we present an RT-qPCR method to detect mink astrovirus in fecal samples from mink kits with diarrhea. All sampled animals were classified based on age and patoanatomical evaluation as having pre-weaning diarrhea, diarrhea in the growth period or as having no macroscopic signs of diarrhea. Fecal samples were analyzed for MiAstV with RT-qPCR, next generation sequencing and electron microscopy in parallel. Mink astrovirus was detected with RT-qPCR in 92 out of 203 samples. This detection was confirmed by next generation sequencing in a high proportion of samples (22/27), and by visualization of astrovirus particles with EM in some of the samples. Mink astrovirus was highly prevalent (68%) among kits in the outbreaks of pre-weaning diarrhea, in particular outbreaks from May, while less prevalent in outbreaks in June. Mink astrovirus was detected in outbreaks of diarrhea in the growth period, though in a much lesser extent than in the pre-weaning period. The role of mink astrovirus in the diarrhea disease complex of mink remain to be investigated, and for that purpose this sensitive and robust RT-qPCR can be a valuable tool in the future., Competing Interests: The authors have declared that no competing interests exist.

Recently, hepe-astrovirus-like RNA viruses named bastroviruses (BastVs), have been found in human, pig, bat, and rat fecal samples. In this study, we determined nearly complete genome sequences of four BastVs in the feces of healthy pigs. Genetic characterization revealed that these porcine BastVs (PBastVs) and BastVs from other animals including humans, had the same genome organization, that is, they contained three predicted conserved domains of viral methyltransferase, RNA helicase, and RdRp in the nonstructural ORF1 and the astrovirus capsid domain in the structural ORF2. Phylogenetic analyses using RNA-dependent RNA polymerase and the capsid region revealed that PBastVs branched with bat and rat BastVs; however, the groups formed by each host were distantly related to human BastVs. Pairwise amino acid sequence comparison demonstrated that PBastVs shared 95.2-98.6% and 76.1-95.5% sequence identity among each other in the ORF1 and ORF2 regions, respectively; the sequence identities between PBastVs and BastVs from other animals were 21.4-42.5% and 9.1-20.6% in the ORF1 and ORF2 regions, respectively. This suggested that BastVs were derived from a common ancestor but evolved independently in each host population during a prolonged period. Putative recombination events were identified in the PBastV genome, suggesting that PBastVs gain sequence diversity and flexibility through recombination events. In an analysis of previously obtained metagenomic data, PBastV sequence reads were detected in 7.3% (23/315) of fecal samples from pigs indicating that PBastVs are distributed among pig populations in Japan., (Copyright © 2020. Published by Elsevier B.V.)

Gastrointestinal disorders caused by enteric viruses are frequently reported in dogs worldwide, with significant mortality rates in unvaccinated individuals. This study reports the identification and molecular characterization of Canine parvovirus (CPV-2), Canine coronavirus (CcoV), Canine astrovirus (AstV), and Canine calicivirus (CcaV) in a panel of dogs showing severe enteric clinical signs sampled in a typical Mediterranean environment (Sardinia, Italy). At least one of these viral species was detected in 92.3% samples. CPV-2 was the most frequently detected virus (87.2%), followed by AsTv (20.5%), CCoV-IIa (18%), and CCoV-I (10.3%). CCoV-IIb and CaCV were not detected in any sample. Single infection was detected in 24 samples (66.7%), mainly related to CPV-2 (91.7%). Coinfections were present in 33.3% samples with constant detection of CPV-2. Canine coronavirus was present only in coinfected animals. The VP2 sequence analysis of CPV-2 positive samples confirmed the presence of all variants, with CPV-2b most frequently detected. Phylogeny based on the CcoV-IIa spike protein (S) gene allowed to identify 2 different clades among Sardinian isolates but failed to distinguish enteric from pantropic viruses. Study on presence and prevalence of enteroviruses in dogs increase our knowledge about the circulation of these pathogens in the Mediterranean area and highlight the need for dedicated routine vaccine prophylaxis. Molecular analyses of enteric viruses are fundamental to avoid failure of vaccines caused by frequent mutations observed in these enteroviruses.

Astroviruses are non-enveloped, positive-sense, ssRNA viruses and often associated with gastrointestinal diseases. Murine astrovirus (MuAstV) was first confirmed in a laboratory mouse colony in 2011. Although infected mice do not present significant clinical symptoms, the virus might interfere with research results. A recent surveillance has shown that MuAstV is highly prevalent in laboratory mice. The aims of the present study were to identify and characterize MuAstV strains as well as to investigate the prevalence rate of viral RNA in laboratory mice in Taiwan, and to estimate the origin and past population demography of MuAstVs. Based on molecular surveillance, MuAstV RNA was detected in 45.7 % of laboratory mice (48/105) from seven of nine colonies. Three fully sequenced MuAstV strains, MuAstV TW1, TW2 and TW3, exhibited 89.1-94.4 % and 89.1-90.0 % nucleotide identities with the reference strains MuAstV STL1 and STL2, respectively. Phylogenetic analyses of the partial regions of the RNA-dependent RNA polymerase (RdRp) and capsid protein (CP) genes of 18 Taiwan strains along with other astroviruses revealed that there are three distinct lineages of mouse astrovirus, MuAstV1, MuAstV2 and mouse astrovirus JF755422. The mutation rates of MuAstV1 were 2.6×10 -4  and 6.2×10 -4 substitutions/site/year for the RdRp and CP regions, respectively. Based on the above molecular clock, the colonization of MuAstV1 in laboratory mice was between 1897 and 1912, in good agreement with the establishment of 'modern' laboratory mouse facilities. Since its initial infection, the population size of MuAstV1 has increased 15-60-fold, probably consistent with the increased use of laboratory mice. In conclusion, MuAstV1 has been associated with modern laboratory mice since the beginning, and its influence on research results may require further investigation.

Many new astroviruses have been identified in humans and other animals in recent years, but only a few have been successfully isolated for extensive biological study. Here, we report an unusual isolation of a porcine astrovirus 5 (PAstV5) strain from a clinical classical swine fever virus (CSFV)-infected tissue sample. Incubation of porcine PK-15 cells with an extract of the CSFV-positive tissue resulted in unexpected cytopathic effects (CPEs), and high-throughput viromic sequencing identified PAstV5 and porcine circovirus type 2 (PCV2) as well as CSFV in the culture. After clearance of CSFV and PCV2, a pure PAstV5 strain, named PAstV5-AH29-2014, was obtained. Analysis revealed virus of typical astroviral morphology with a genome of 6,448 nucleotides, sharing 84.3 to 88.9% nucleotide identity with previously published PAstV5 strains. A mechanistic study showed that CSFV coinfection was likely an important factor for successful isolation by significantly enhancing PAstV5 replication in PK-15 cells via suppression of a type I interferon response. Altogether, PAstV5-AH29-2014, as the first isolated PAstV5 strain, will provide critical material for the investigation of the biological and pathogenic properties of this virus as well as for future development of relevant biological and diagnostic reagents. IMPORTANCE Porcine astroviruses are mainly associated with gastroenteritis and neurological diseases in pigs, and five genotypes have been identified (PAstV1-5). However, the clinical manifestations of genotypes other than PAstV1 have not yet been determined because of the failure of in vitro virus isolation. Here, we report a surprising isolation of a PAstV5 strain from a clinical classical swine fever virus (CSFV)-infected tissue sample, which can stably passage in PK-15 cells, and coinfection with CSFV significantly enhanced the replication of PAstV5, possibly through suppression of beta interferon production. Thus, the first isolated PAstV5 strain will be useful for investigating the biological and pathogenic properties of this virus, and the findings obtained in this study provide new insights into defining the interaction mechanism between CSFV and PAstV5., (Copyright © 2020 American Society for Microbiology.)

Outbreaks of gosling gout have occurred in China since 2017 and caused a considerable economic impact on the poultry industry. While gosling astrovirus (GoAstV) is believed to be the main causal pathogen of gout, the full-blown disease of gout cannot be well reproduced by infecting the goslings with GoAstV, suggesting the possibility of other infectious agents being involved with the development of gosling gout. To assess other possible infectious agents, we collected tissues from gout-affected goslings in 12 goose farms in China, followed by PCR detection of GoAstV, goose reovirus (GRV), goose parvovirus (GPV), fowl adenovirus (FAdV), goose circovirus (GcoV), Tembusu virus (TMUV) and goose haemorrhagic polyomavirus (GHPV). Our data showed that all gout-affected goslings carried both of GoAstV and GPV determined by PCRs, and this was further confirmed by fluorescence multiplex immunohistochemical staining, and phylogenetic analysis of ORF2 gene of GoAstV and VP3 gene of GPV. In addition to the haemorrhage in the kidney, liver, spleen and lung of the gout-affected goslings, histological examinations showed also extensive infiltration of heterophil myelocytes in the kidney, liver, spleen, bursa of Fabricius, thymus, lungs and pancreas. Our findings strongly suggest that coinfection of GoAstV and GPV increases the severity of gout. While this is the first study to report GPV in gout-affected goslings, further studies including infection model are warranted to investigate the role of GPV and its coinfection with GoAstV in the development of gosling gout., (© 2020 Blackwell Verlag GmbH.)

Goose astrovirus (GAstV) causes a novel disease characterized by urate deposition in the viscera and joints in goslings in many provinces of China, leading to huge economic losses in the goose industry. To better understand the genetic diversity of GAstV in the Anhui Province, Central-Eastern China, 48 kidney samples from goslings with gout were subjected to reverse-transcription polymerase chain reaction (RT-PCR) analysis for detecting GAstV, and phylogenetic analysis of whole genomes and ORFs was performed. Thirty-five samples were GAstV-positive, indicating that the virus is a frequent cause of gout. The whole genomes of 5 GAstV strains were successfully sequenced and named AHAU1-5. The sequenced genomes and those of reference GAstV strains in GenBank displayed 97.4-99.8% similarity. The isolates had high nucleotide sequence similarity with the GAstV reference strain SDPY. A phylogenetic analysis showed that AHAU1 and AHAU4 were closely related to the reference strain SDPY; AHAU2, AHAU3, and AHAU5 formed separate branches. Furthermore, recombination analysis revealed putative recombination sites in the Jiangsu strains that originated from strains in the Anhui and Shandong Provinces, accompanied by the recombination of different strains in the Anhui Province. This study is the first to carry out systematic phylogenetic analysis of GAstV isolated in the Anhui Province, Central-Eastern China. By improving our understanding of the diversity of GAstV in the Anhui Province, these results provide a basis for the prevention and control of its spread., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Porcine astrovirus (PAstV), associated with mild diarrhea and neurological disease, is transmitted in pig farms worldwide. The purpose of this study is to elucidate the main factors affecting codon usage to PAstVs. Phylogenetic analysis showed that the subtype PAstV-5 sat at the bottom of phylogenetic tree, followed by PAstV-3, PAstV-1, PAstV-2, and PAstV-4, indicating that the five existing subtypes (PAstV1-PAstV5) may be formed by multiple differentiations of PAstV ancestors. A codon usage bias was found in the PAstVs-2,3,4,5 from the analyses of effective number of codons (ENC) and relative synonymous codon usage (RSCU). Nucleotides A/U are more frequently used than nucleotides C/G in the genome CDSs of the PAstVs-3,4,5. Codon usage patterns of PAstV-5 are dominated by mutation pressure and natural selection, while natural selection is the main evolutionary force that affects the codon usage pattern of PAstVs-2,3,4. The analyses of codon adaptation index (CAI), relative codon deoptimization index (RCDI), and similarity index (SiD) showed the codon usage similarities between the PAstV and animals might contribute to the broad host range and the cross-species transmission of astrovirus. Our results provide insight into understanding the PAstV evolution and codon usage patterns.

To visually and rapidly detect a novel goose astrovirus (N-GoAstV) causing fatal gout in goslings, an isothermal detection method based on one-step reverse transcription loop-mediated isothermal amplification (one-step RT-LAMP) was established. The one-step RT-LAMP assay for N-GoAstV detection, using Bst 3.0 DNA polymerase with strong reverse transcription activity and primer sets targeting the opening reading frame 1b (ORF1b) of N-GoAstV, could be completed in 30 min using a water bath at 61°C; the detection results could be visually observed by adding a pH-sensitive dye containing phenol red and cresol red. The detection limit of the one-step RT-LAMP assay was 57.8 copies, which was similar to that of reverse transcription-quantitative polymerase chain reaction. The assay specifically detected N-GoAstV without any cross-reaction with other reference viruses, and this was further confirmed using enzyme digestion. These results indicated that the newly established RT-LAMP assay could accomplish reverse transcription, amplification, and visual result determination in one step, and the results obtained via this rapid and cost-effective method could be used to support disease control on farms in terms of N-GoAstV infection., (Copyright © 2020. Published by Elsevier Inc.)

Wild birds are major natural reservoirs and potential dispersers of a variety of infectious diseases. As such, it is important to determine the diversity of viruses they carry and use this information to help understand the potential risks of spillover to humans, domestic animals, and other wildlife. We investigated the potential viral causes of paresis in long-standing, but undiagnosed, disease syndromes in wild Australian birds. RNA from diseased birds was extracted and pooled based on tissue type, host species, and clinical manifestation for metagenomic sequencing. Using a bulk and unbiased metatranscriptomic approach, combined with clinical investigation and histopathology, we identified a number of novel viruses from the families Astroviridae, Adenoviridae, Picornaviridae, Polyomaviridae, Paramyxoviridae, Parvoviridae , and Circoviridae in common urban wild birds, including Australian magpies, magpie larks, pied currawongs, Australian ravens, and rainbow lorikeets. In each case, the presence of the virus was confirmed by reverse transcription (RT)-PCR. These data revealed a number of candidate viral pathogens that may contribute to coronary, skeletal muscle, vascular, and neuropathology in birds of the Corvidae and Artamidae families and neuropathology in members of the Psittaculidae The existence of such a diverse virome in urban avian species highlights the importance and challenges in elucidating the etiology and ecology of wildlife pathogens in urban environments. This information will be increasingly important for managing disease risks and conducting surveillance for potential viral threats to wildlife, livestock, and human health. IMPORTANCE Wildlife naturally harbor a diverse array of infectious microorganisms and can be a source of novel diseases in domestic animals and human populations. Using unbiased RNA sequencing, we identified highly diverse viruses in native birds from Australian urban environments presenting with paresis. This research included the clinical investigation and description of poorly understood recurring syndromes of unknown etiology: clenched claw syndrome and black and white bird disease. As well as identifying a range of potentially disease-causing viral pathogens, this study describes methods that can effectively and efficiently characterize emergent disease syndromes in free-ranging wildlife and promotes further surveillance for specific pathogens of potential conservation and zoonotic concern., (Copyright © 2020 Chang et al.)

To investigate the prevalence of murine astrovirus (MuAstV) in mice in laboratory animal facilities in Japan, a polymerase chain reaction (PCR) test targeting the RNA-dependent RNA polymerase (RdRP) gene was performed on the cecum contents of 1,212 mice (1,183 immunocompetent mice and 29 immunodeficient mice) from 226 facilities. The results showed that 118 (52.2%) of the 226 facilities were positive for MuAstV. Out of the 1,212 mice, 424 (35.0%) were positive. No gross lesions were observed in any of the mice examined. A phylogenetic analysis for 15 selected strains revealed that 13 strains formed one cluster, while two were genetically distant from that cluster. These results suggest that multiple strains are prevalent in laboratory mice in Japan.

Parechovirus A (PeV-A), which causes a wide variety of diseases, is prevalent among young children. However, little is currently known about PeV-A infections in children with acute gastroenteritis in mainland China. In this study, we investigated the molecular epidemiology of acute gastroenteritis in Shenzhen, southern China, with an emphasis on PeV-A infections. A total of 1220 stool specimens from 1220 outpatient children under 5 years old with acute gastroenteritis were collected from January 2016 to December 2018. Viral RNA was detected by a real-time RT-PCR and PCR method. The PeV-A isolates were genotyped by sequencing the VP3/VP1 region. Of 1220 specimens, 148 (12.1%) were positive for PeV-A. The predominant genotype was PeV-A 1B (68.9%), followed by PeV-A 4 (12.2%), PeV-A 14 (6.1%), PeV-A 1A (5.4%), PeV-A 6 (2.7%), PeV-A 3 (2.7%) and PeV-A 5 (2.0%). It was found that 68.2% of PeV-A infections occurred in the summer and rainy months (June to September) in southern China. The majority of PeV-A-positive patients (97.3%) were younger than 24 months old. PeV-A coinfection with norovirus, rotavirus, astrovirus and adenovirus was found in thirty specimens (30/148, 20.3%), five specimens (5/148, 3.4%), five specimens (5/148, 3.4%), and two specimens (2/148, 1.4%), respectively. Coinfections with more than one other enteric virus were not observed in any of the PeV-A-positive specimens. Phylogenetic analysis revealed that the PeV-A isolates from Shenzhen were closely related to each other and to strains circulating in China, suggesting endemic circulation of PeV-A in China. The results of this study indicate that PeV-A is one of important pathogens of acute gastroenteritis in young children and that coinfection is a possible mode of PeV-A infection. PeV-A associated with acute gastroenteritis exhibited high genotypic diversity in Shenzhen, southern China.

In this study, starting from nucleic acids purified from the brain tissue, Nanopore technology was used to identify the etiological agent of severe neurological signs observed in a cow which was immediately slaughtered. Histological examination revealed acute non-suppurative encephalomyelitis affecting the brainstem, cerebrum, cerebellum, and medulla oblongata, while by using PCR-based assays, the nucleic acids of major agents for neurological signs were not detected. By using Nanopore technology, 151 sequence reads were assigned to Bovine Astrovirus (BoAstV). Real-time RT-PCR and in situ hybridization (ISH) confirmed the presence of viral RNA in the brain. Moreover, using the combination of fluorescent ISH and immunofluorescence (IF) techniques, it was possible to detect BoAstV RNA and antigens in the same cells, suggesting the active replication of the virus in infected neurons. The nearly whole genome of the occurring strain (BoAstV PE3373/2019/Italy), obtained by Illumina NextSeq 500, showed the highest nucleotide sequence identity (94.11%) with BoAstV CH13/NeuroS1 26,730 strain, an encephalitis-associated bovine astrovirus. Here, we provide further evidence of the role of AstV as a neurotropic agent. Considering that in a high proportion of non-suppurative encephalitis cases, which are mostly indicative of a viral infection, the etiologic agent remains unknown, our result underscores the value and versatility of Nanopore technology for a rapid diagnosis when the PCR-based algorithm gives negative results.

In 2019, a novel goose astrovirus (GoAstV) epidemiological investigation on geese was conducted in Shandong province, China. During the investigation, a high prevalence of novel GoAstV was observed in symptom-free breeding geese flocks. Moreover, the novel GoAstV-specific RNA was detected in either breeder birds or their progenies. To verify the hypothesis that the novel GoAstV could be transmitted vertically, a total of 42 WuLong breeder geese, aged 335 days, were equally divided into three groups for experimental infection. The SDPY isolate of novel GoAstV (A/goose/Shandong/SDPY/2018, SDPY), preserved in our laboratory, was injected intramuscularly to subjects of group A while orally inoculated to those of group B. After the inoculation, novel GoAstV RNA was detected in vitelline membrane, embryos, and allantoic fluid of goose embryos in novel GoAstV infected groups. Moreover, the ORF2 gene of novel GoAstV from vitelline membrane, embryo, allantoic fluid as well as gosling shared almost 100 % nucleotide homology to a novel GoAstV virus isolated from the goose ovary which produced the egg, suggesting that the novel GoAstV can be vertically transmitted in the goose. Taken together, the findings provide evidence of possible vertical transmission of novel GoAstV from breeding goose to goslings., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest., (Copyright © 2020. Published by Elsevier B.V.)

Background: Although astroviruses (AstV) have been detected in a variety of host species, there are only limited records of their occurrence in deer. One of the most important game species in Europe, due to its meat and antlers, is roe deer. Infected game animals can pose a threat to the health of other animals and of humans, so more attention needs to be focused on understanding the diversity of viruses in wildlife. The complete genome and organization of the roe deer AstV genome have not so far been described., Results: In our study, 111 game animals were screened for the presence of AstV. While no AstVs were detected in red deer, wild boar, chamois and mouflon, AstV RNA was present in three samples of roe deer. They were further subjected to whole genome sequencing with next generation sequencing. In this study, two AstV genomes were assembled; one in sample D5-14 and one in sample D12-14, while, in sample D45-14, no AstV sequences were identified. The complete coding sequences of the AstV SLO/D5-14 strain genome and of the almost complete genome of the AstV SLO/D12-14 strain were determined. They showed a typical Mamastrovirus organization. Phylogenetic analyses and amino acid pairwise distance analysis revealed that Slovenian roe deer AstV strains are closely related to each other and, also, related to other deer, bovine, water buffalo, yak, Sichuan takin, dromedary, porcine and porcupine AstV strains - thus forming a highly supported group of currently unassigned sequences., Conclusions: Our findings suggest the existence of a new Mamastrovirus genogroup might be constituted while this aforementioned group is distantly related to Mamastrovirus genogroups I and II. In this study, additional data supporting a novel taxonomic classification are presented.

We report the identification of astrovirus WI65268 in a white-tailed deer with respiratory disease in the United States in 2018. This virus is a recombinant of Kagoshima1-7 and Kagoshima2-3-2 (both bovine astroviruses from Japan) and was characterized as a potential new genotype. Further surveillance of deer might help identify related isolates.

The advent of unbiased metagenomic virus discovery has revolutionized studies of virus biodiversity and evolution. Despite this, our knowledge of the virosphere, including in mammalian species, remains limited. We used unbiased metagenomic sequencing to identify RNA viruses in European field voles and rabbits. Accordingly, we identified a number of novel RNA viruses including astrovirus, rotavirus A, picorna-like virus and a morbilli-like paramyxovirus. In addition, we identified a sobemovirus and a novel luteovirus that likely originated from the rabbit diet. These newly discovered viruses were often divergent from those previously described. The novel astrovirus was most closely related to a virus sampled from the rodent-eating European roller bird ( Coracias garrulous ). PCR screening revealed that the novel morbilli-like paramyxovirus in the UK field vole had a prevalence of approximately 4%, and shared common ancestry with other rodent morbilli-like viruses sampled globally. Two novel rotavirus A sequences were detected in a UK field vole and a French rabbit, the latter with a prevalence of 5%. Finally, a highly divergent picorna-like virus found in the gut of the French rabbit virus was only ~35% similar to an arilivirus at the amino acid level, suggesting the presence of a novel viral genus within the Picornaviridae .

Astroviral infection is considered to be one of the causes of mammalian diarrheal diseases. It has been shown that astrovirus infections cause varying degrees of diarrhea in turkeys and mice. However, the pathogenesis of porcine astrovirus is unknown. In this study, the virulence of a cytopathic porcine astrovirus (PAstV) strain (PAstV1-GX1) isolated from the PK-15 cell line was tested using seven-day-old nursing piglets. The results showed that PAstV1-GX1 infection could cause mild diarrhea, growth retardation, and damage of the villi of the small intestinal mucosa. However, all the above symptoms could be restored within 7 to 10days post inoculation (dpi). To evaluate the innate immunity response of PAstV in vivo, the alteration of inflammatory cytokine expression in piglets infected with PAstV1-GX1 was determined using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The mRNA expression levels of the IFNβ and ISG54 were found to be significantly elevated in virus-infected piglets. In contrast, expression of IFNλ was downregulated in piglets infected with PAstV1-GX1. In addition, the mRNA expression of the tight junction protein 1 and 2 and zonula occludin 1, which are associated with the intestinal barrier permeability, were affected after PAstV1 infection. The present study adds to our understanding of the pathogenic mechanism of PAstV and has established an animal model for further study of pig astrovirus infection.

Astroviruses (AstVs) have a very wide range of hosts and are associated with enteric and extra-enteric disease in mammals and birds. Cross-species transmission of AstVs has been observed frequently. In the present study, the genome of a novel astrovirus from Amur tigers (Panthera tigris) from a zoo in China was characterized and was found to have the typical genomic features of other mammal AstVs. It showed the highest nucleotide sequence similarity (46.1-87.3% identity) to AstVs from cats, indicating a close phylogenetic relationship and possible cross-species transmission between them. To our knowledge, this is the first identification and characterization of AstV from tigers, and this virus is the third astrovirus identified in hosts of the family Felidae. The results of this study will be helpful for understanding the origin, genetic diversity, and cross-species transmission of AstV.

Goose astrovirus is a novel and distinct astrovirus that causes fatal visceral gout in 4- to 21-day-old goslings. Goose parvovirus is the etiologic agent of Derzsy disease, an acute, contagious, and fatal disease that affects mainly young goslings. This paper describes the clinical signs and gross and histopathologic features of co-infection with astrovirus and goose parvovirus. Clinical signs and history included increased mortality, depression, anorexia, enteritis, joint swelling, and paralysis. Postmortem examination showed a considerable amount of urate covering the internal organs, especially the heart, liver, and kidney. Some goslings had swollen duodenum and ileum. Histologic lesions in the kidney, liver, spleen, lung, proventriculus, and brain included hemorrhage, congestion, edema, cell necrosis, inflammatory cell infiltration, and an eosinophilic protein-like substance in renal tubules. The extensive infiltration of heterophil myelocytes into the kidney, spleen, liver, lung, bursa of Fabricius, and pancreas is a new finding.

Here we describe the identification and genetic characterization of a porcine hepe-astrovirus, or bastrovirus, obtained from feces from pigs in the United States. The genome of the new bastrovirus is 5,955 nt long and contains two open reading frames (ORFs). ORF1 encodes a protein containing three domains, viral methyltransferase, RNA helicase and RNA-dependent RNA polymerase (RdRp), and is closely related to the RdRp of hepatitis E virus. The ORF2 protein shares similarities with the astrovirus capsid precursor protein. Although structural features of bastroviruses may resemble those of astroviruses, distinct characteristics of the newly identified bastrovirus include the presence of an RNA helicase domain in ORF1 and the lack of ORF1b. In addition to genetic characterization, screening of 368 porcine samples (oral fluids, oral swabs or fecal swabs) collected in the United States (US) using a porcine-bastrovirus-specific real-time PCR assay revealed that 31% of those samples were positive. These results suggest a broad distribution of bastroviruses in the swine population in the US. This represents the first description of bastrovirus in swine in the US.

The discovery and analysis of pathogens carried by non-human primates are important for understanding zoonotic infections in humans. We identified a highly divergent astrovirus (AstV) from fecal matter from a rhesus monkey in China, which has been tentatively named "monkey-feces-associated AstV" (MkAstV). The full-length genome of MkAstV was determined to be 7377 nt in length. It exhibits the standard genomic AstV organization of three open reading frames (ORFs) and is most closely related to duck AstV (28%, 49%, and 35% amino acid sequence identity in ORF1a, ORF1b, and ORF2, respectively). Coincidentally, while this report was being prepared, an astrovirus sequence from Hainan black-spectacled toad became available in the GenBank database, showing 95%, 94% and 92% aa sequence identity in ORF1a, ORF1b and ORF2, respectively, to the corresponding ORFs of MkAstV. Phylogenetic analysis of ORF1a, ORF1b, and ORF2 indicated that MkAstV and the amphibian-related astroviruses formed an independent cluster in the genus Avastrovirus. The host of MkAstV remains unknown. Epidemiological and serological studies of this novel virus should be undertaken in primates, including humans.

Commensal microbes profoundly impact host immunity to enteric viral infections 1 . We have shown that the bacterial microbiota and host antiviral cytokine interferon-λ (IFN-λ) determine the persistence of murine norovirus in the gut 2,3 . However, the effects of the virome in modulating enteric infections remain unexplored. Here, we report that murine astrovirus can complement primary immunodeficiency to protect against murine norovirus and rotavirus infections. Protection against infection was horizontally transferable between immunocompromised mouse strains by co-housing and fecal transplantation. Furthermore, protection against enteric pathogens corresponded with the presence of a specific strain of murine astrovirus in the gut, and this complementation of immunodeficiency required IFN-λ signalling in gut epithelial cells. Our study demonstrates that elements of the virome can protect against enteric pathogens in an immunodeficient host.

Background: Human astroviruses (HAstVs) are one of the major causes of acute gastroenteritis. Classic HAstVs can be classified into eight genotypes. We investigated the positive rate of HAstVs and the distribution of HAstV genotypes in strains isolated from patients with acute gastroenteritis in Hwaseong, Korea, in 2013-2017., Methods: Between November 2013 and December 2017, 3,519 stool samples were collected from patients with symptoms of acute gastroenteritis and tested for HAstV using multiplex PCR. For HAstV-positive samples, the ORF2 gene, which encodes a capsid protein, was genotyped by reverse-transcription PCR and sequencing. Phylogenetic analysis was performed to determine whether the sequences of the HAstVs differed by year., Results: The positive rate of HAstV was 1.9% (67 samples). HAstV Type 1 was the most prevalent genotype (82.4%), and Types 4, 5, and 8 were also detected. Infection occurred year-round, with no distinct seasonal variation. Infection occurred at nearly all ages (55 days-81 years; median: 3 years), and the positive rate was substantially higher in children younger than five years. Phylogenetic analysis revealed three distinct clades of HAstV Type 1 according to the collection time., Conclusions: Our results provide recent epidemiological data on HAstVs in Korea between 2013 and 2017. The finding of three distinct clades of HAstV Type 1 according to collection time suggests genetic evolution of HAstVs. These findings can enhance our knowledge on HAstV infection and viral evolution., Competing Interests: No potential conflicts of interest relevant to this study are reported., (© The Korean Society for Laboratory Medicine.)

Human astroviruses are single-stranded RNA enteric viruses that cause a spectrum of disease ranging from asymptomatic infection to systemic extragastrointestinal spread; however, they are among the least-characterized enteric viruses, and there is a lack of a well-characterized small animal model. Finding that immunocompromised mice were resistant to human astrovirus infection via multiple routes of inoculation, our studies aimed to determine whether murine astrovirus (MuAstV) could be used to model human astrovirus disease. We experimentally infected wild-type mice with MuAstV isolated from immunocompromised mice and found that the virus was detected throughout the gastrointestinal tract, including the stomach, but was not associated with diarrhea. The virus was also detected in the lung. Although virus levels were higher in recently weaned mice, the levels were similar in male and female adult mice. Using two distinct viruses isolated from different immunocompromised mouse strains, we observed virus strain-specific differences in the duration of infection (3 versus 10 weeks) in wild-type mice, indicating that the within-host immune pressure from donor mice shaped the virus kinetics in immunocompetent recipient hosts. Both virus strains elicited minimal pathology and a lack of sustained immunity. In summary, MuAstV represents a useful model for studying asymptomatic human infection and gaining insight into the astrovirus pathogenesis and immunity. IMPORTANCE Astroviruses are widespread in both birds and mammals; however, little is known about the pathogenesis and the immune response to the virus due to the lack of a well-characterized small-animal model. Here we describe two distinct strains of murine astrovirus that cause infections in immunocompetent mice that mirror aspects of asymptomatic human infections, including minimal pathology and short-lived immunity. However, we noted that the duration of infection differed greatly between the strains, highlighting an important facet of these viruses that was not previously appreciated. The ubiquitous nature and diversity of murine astroviruses coupled with the continuous likelihood of reinfection raise the possibility of viral interference with other mouse models of disease., (Copyright © 2019 American Society for Microbiology.)

Birds are the natural reservoir of viruses with zoonotic potential, as well as contributing to the evolution, emergence, and dissemination of novel viruses. In this study, we applied a high-throughput screening approach to identify the diversity of viruses in 118 samples of birds captured between October 2006 to October 2010 in the North and Northeast regions of Brazil. We found nearly complete genomes of novel species of astrovirus and calicivirus in cloacal swabs of ruddy turnstones (Arenaria interpres) collected in Coroa do Avião islet, Pernambuco State. These viruses are positive-sense single-stranded RNA with a genome of ~7 to 8 kb, and were designated as Ruddy turnstone astrovirus (RtAstV) and Ruddy turnstone calicivirus (RTCV), respectively. Phylogenetic analysis showed that RtAstV and RTCV grouped in a monophyletic clade with viruses identified from poultry samples (i.e., chicken, goose, and turkey), including viruses associated with acute nephritis in chickens. Attempts of viral propagation in monkey and chicken cell lines for both viruses were unsuccessful. Also, we found genomes related with viral families that infect invertebrates and plants, suggesting that they might be ingested in the birds' diet. In sum, these findings shed new light on the diversity of viruses in migratory birds with the notable characterization of a novel astrovirus and calicivirus.

Astroviruses (AstVs) are mostly responsible for mild to severe gastroenteritis infections in humans and animals. AstVs infect a wide range of host species, have a large genetic diversity with different circulating variants and are thus a high zoonotic risk for human populations. Among these host species, rodents are known to harbor several AstVs variants. Therefore, it is important to identify in rodent species which AstVs are circulating and evaluate their potential zoonotic risk for humans. In this context, this study aimed to screen the presence of AstVs in 267 rodents trapped in 2012 in Franceville and Makokou, two cities in Gabon. RNA extracted from grinded intestines were used for the screening of AstVs by amplification of a conserved region of the RNA dependent RNA polymerase. Results report the identification of AstVs in 12 individuals (4.6% rate), belonging to three different species including Rattus rattus, Mus musculus and Hybomys univittatus. These findings report the first identification of AstVs in R. rattus and H. univittatus. The phylogenetic analyses indicate host specificity of rodents AstVs. The absence of rodent AstVs within the human AstV clade suggests a low rate of interspecies transmission of these viruses and consequently a low zoonotic risk., (Copyright © 2018 Elsevier B.V. All rights reserved.)