Construction of a reverse genetic system for porcine astrovirus

Rapid Rescue of Goose Astrovirus Genome via Red/ET Assembly

The host-specific infection of Avian Astrovirus (AAstVs) has posed significant challenges to the poultry industry, resulting in substantial economic losses. However, few reports exist on the functional consequences of genome diversity, cross-species infectivity and mechanisms governing virus replication of AAstVs, making it difficult to develop measures to control astrovirus transmission. Reverse genetics technique can be used to study the function of viruses at the molecular level, as well as investigating pathogenic mechanisms and guide vaccine development and disease treatment. Herein, the reverse genetics technique of goose astrovirus GAstV/JS2019 strain was developed based on use of a reconstructed vector including CMV promotor, hammerhead ribozyme (HamRz), hepatitis delta virus ribozyme (HdvRz), and SV40 tail, then the cloned viral genome fragments were connected using Red/ET recombineering. The recombinant rGAstV-JS2019 was readily rescued by transfected the infectious clone plasmid into LMH cells. Importantly, the rescued rGAstV/JS2019 exhibited similar growth kinetics comparable to those of the parental GAstV/JS2019 isolate in cultured cells. Our research results provide an alternative and more effective reverse genetic tool for a detailed understanding of viral replication, pathogenic mechanisms, and molecular mechanisms of evolution.

Attenuation hotspots in neurotropic human astroviruses

During the last decade, the detection of neurotropic astroviruses has increased dramatically. The MLB genogroup of astroviruses represents a genetically distinct group of zoonotic astroviruses associated with gastroenteritis and severe neurological complications in young children, the immunocompromised, and the elderly. Using different virus evolution approaches, we identified dispensable regions in the 3' end of the capsid-coding region responsible for attenuation of MLB astroviruses in susceptible cell lines. To create recombinant viruses with identified deletions, MLB reverse genetics (RG) and replicon systems were developed. Recombinant truncated MLB viruses resulted in imbalanced RNA synthesis and strong attenuation in iPSC-derived neuronal cultures confirming the location of neurotropism determinants. This approach can be used for the development of vaccine candidates using attenuated astroviruses that infect humans, livestock animals, and poultry.

Replication of Porcine Astrovirus Type 1-Infected PK-15 Cells In Vitro Affected by RIG-I and MDA5 Signaling Pathways

The interferon (IFN) system is an extremely powerful antiviral response in animal cells. The subsequent effects caused by porcine astrovirus type 1 (PAstV1) IFN activation are important for the host's response to viral infections. Here, we show that this virus, which causes mild diarrhea, growth retardation, and damage of the villi of the small intestinal mucosa in piglets, induces an IFN response upon infection of PK-15 cells. Although IFN-β mRNA was detected within infected cells, this response usually occurs during the middle stages of infection, after genome replication has taken place. Treatment of PAstV1-infected cells with the interferon regulatory factor 3 (IRF3) inhibitor BX795 decreased IFN-β expression, whereas the nuclear factor kappa light chain enhancer of activated B cells (NF-κB) inhibitor BAY11-7082 did not. These findings indicate that PAstV induced the production of IFN-β via IRF3-mediated rather than NF-κB-mediated signaling pathways in PK-15 cells. Moreover, PAstV1 increased the protein expression levels of retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5) in PK-15 cells. The knockdown of RIG-I and MDA5 decreased the expression levels of IFN-β and the viral loads and increased the infectivity of PAstV1. In conclusion, PAstV1 induced the production of IFN-β via the RIG-I and MDA5 signaling pathways, and the IFN-β produced during PAstV1 infection inhibited viral replication. These results will help provide new evidence that PAstV1-induced IFNs may protect against PAstV replication and pathogenesis. IMPORTANCE Astroviruses (AstVs) are widespread and can infect multiple species. Porcine astroviruses produce mainly gastroenteritis and neurological diseases in pigs. However, astrovirus-host interactions are less well studied, particularly with respect to their antagonism of IFN. Here, we report that PAstV1 acts via IRF3 transcription pathway activation of IFN-β. In addition, the knockdown of RIG-I and MDA5 attenuated the production of IFN-β induced by PAstV1 in PK-15 cells and increased efficient viral replication in vitro. We believe that these findings will help us to better understand the mechanism of how AstVs affect the host IFN response.

Insertion of exogenous genes within the ORF1b coding region of porcine astrovirus

Porcine astrovirus (PAstV) is a common cause of diarrhea in swine farms. The current understanding of the molecular virology and pathogenesis of PAstV is incomplete, especially due to the limited functional tools available. Here, ten sites in the open reading frame 1b (ORF1b) of the PAstV genome were determined to tolerate random 15 nt insertions based on the infectious full-length cDNA clones of PAstV using transposon-based insertion-mediated mutagenesis of three selected regions of the PAstV genome. Insertion of the commonly used Flag tag into seven of the ten insertion sites allowed the production of infectious viruses and allowed their recognition by specifically labeled monoclonal antibodies. Indirect immunofluorescence showed that the Flag-tagged ORF1b protein partially overlapped with the coat protein within the cytoplasm. An improved light-oxygen-voltage (iLOV) gene was also introduced into these seven sites, and only one viable recombinant virus that expressed the iLOV reporter gene at the B2 site was recovered. Biological analysis of the reporter viruses showed that these exhibited similar growth characteristics to the parental virus, but they produced fewer infectious virus particles and replicated at a slower rate. The recombinant viruses containing iLOV fused to ORF1b protein, which maintained their stability and displayed green fluorescence for up to three generations after passaging in cell culture. The porcine astroviruses (PAstVs) expressing iLOV were then used to assess the in vitro antiviral activities of mefloquine hydrochloride and ribavirin. Altogether, the recombinant PAstVs expressing iLOV can be used as a reporter virus tool for the screening of anti-PAstV drugs as well as the investigation of PAstV replication and the functional activities of proteins in living cells.

A peptide-based ELISA for detection of antibodies against novel goose astrovirus type 1

Goose gout disease is a high morbidity and mortality disease caused by novel serotype 1 goose astrovirus (GAstV-1), which has resulted in huge economic loss to the goose industry of China. However, few diagnostic methods have been developed for serological surveillance of GAstV-1. In our previous study, several novel B cell epitopes were identified in the ORF2 protein of GAstV-1. In this study, one novel peptide of 627-646 aa in the ORF2 recognized by monoclonal antibody (mAb) 6C6 was used as an antigen to develop an efficient peptide-based ELISA (pELISA) for detection of antibodies against GAstV-1. Specificity analysis showed that the pELISA only reacted with sera against GAstV-1, but not with sera against other pathogens tested. The sensitivity of the pELISA in detecting positive sera was higher than that of the IFA (Indirect immunofluorescence assay). The coefficients of variation (CV) of the intra-assay and inter-assay were both < 10%, indicating that the reproducibility of pELISA was good. For detection of clinical samples, the pELISA had 87.5% concordance with the IFA. Our data demonstrate that the pELISA generated here provides an accurate, rapid, and economical method for the detection antibodies against GAstV-1 for serological surveillance.

An IgY Effectively Prevents Goslings from Virulent GAstV Infection

Goose astrovirus (GAstV) leads to viscera and joints urate deposition in 1- to 20-day-old goslings, with a mortality rate of up to 50%, posing a severe threat to entire colonies; however, there is no efficient prevention and control method for GAstV infection. This study describes a prophylactic anti-GAstV strategy based on the specific immunoglobulin Y (IgY) from egg yolk. The specific IgY was produced by 22-week-old laying hens intramuscularly immunized with the inactivated GAstV three consecutive times, with 2-week intervals. The egg yolk was collected weekly after the immunization and the anti-GAstV IgY titer was monitored using an agar gel immune diffusion assay (AGID). The results revealed that the AGID titer began to increase on day 7, reached a peak on day 49, and remained at a high level until day 77 after the first immunization. The specific IgY was prepared from the combinations of egg yolk from day 49 to day 77 through PEG-6000 precipitation. Animal experiments were conducted to evaluate the effects of prevention and treatment. The result of the minimum prophylactic dose of the IgY showed that the protection rate was 90.9% when 2.5 mg was administrated. Results of the prevention and the treatment experiments showed prevention and cure rates of over 80% when yolk antibody was administered in the early stages of the GAstV infection. These results suggested that the specific IgY obtained from immunized hens with the inactivated GAstV could be a novel strategy for preventing and treating GAstV infection.

Genomic Divergence Characterization and Quantitative Proteomics Exploration of Type 4 Porcine Astrovirus

Porcine astrovirus (PAstV) has been identified as an important diarrheic pathogen with a broad global distribution. The PAstV is a potential pathogen to human beings and plays a role in public health. Until now, the divergence characteristics and pathogenesis of the PAstV are still not well known. In this study, the PAstV-4 strain PAstV/CH/2022/CM1 was isolated from the diarrheal feces of a piglet in Shanghai, which was identified to be a recombination of PAstV4/JPN (LC201612) and PAstV4/CHN (JX060808). A time tree based on the ORF2 protein of the astrovirus demonstrated that type 2–5 PAstV (PAstV-2 to 5) diverged from type 1 PAstV (PAstV-1) at a point from 1992 to 2000. To better understand the molecular basis of the virus, we sought to explore the host cell response to the PAstV/CH/2022/CM1 infection using proteomics. The results demonstrate that viral infection elicits global protein changes, and that the mitochondria seems to be a primary and an important target in viral infection. Importantly, there was crosstalk between autophagy and apoptosis, in which ATG7 might be the key mediator. In addition, the NOD-like receptor X1 (NLRX1) in the mitochondria was activated and participated in several important antiviral signaling pathways after the PAstV/CH/2022/CM1 infection, which was closely related to mitophagy. The NLRX1 may be a crucial protein for antagonizing a viral infection through autophagy, but this has yet to be validated. In conclusion, the data in this study provides more information for understanding the virus genomic characterization and the potential antiviral targets in a PAstV infection.

Identification of three novel B cell epitopes in ORF2 protein of the emerging goose astrovirus and their application

The outbreak of goose gout disease caused by novel goose astrovirus type 1 (GAstV-1) has resulted in huge economic losses to the goose industry in China since 2017. However, little is known about the B cell epitopes in major antigen of GAstV-1 and the serological approach for detection of GAstV-1 is not available. In this study, three novel monoclonal antibodies (mAbs) against the ORF2 protein were first generated and designated as 3G6, 5H7, and 6C6, respectively. Epitope mapping revealed that mAb 3G6, 5H7, and 6C6 recognized ₆₉₅AVRFEKGGHE₇₀₄, ₆₈₅EKALSAPQAG₆₉₄, and ₆₃₅DDDPLSDVTS₆₄₄ in ORF2, respectively. Sequence alignments found that the three epitopes were highly conserved in GAstV-1 but not in other AAstV members. Moreover, a mAb-based sandwich ELISA for the detection of GAstV-1 was first developed using mAb 6C6. The sandwich ELISA only reacted with GAstV-1 but not with GAstV-2 and the other goose-associated viruses tested. The limit of the detection of the sandwich ELISA reaches 1.58 × 10³ TCID₅₀/mL of GAstV-1. Notably, mAb 6C6 could also efficiently react with the GAstV-1 in tissue frozen sections of the clinical infected goose through IFA. The mAbs generated in this study pave the way for further studying on the role of ORF2 in the infection and pathogenesis of GAstV, and the sandwich ELISA and the tissue frozen section-IFA approaches established here provide efficient and rapid serological diagnostic tools for detection of GAstV-1. KEY POINTS: • Three novel B cell epitopes were identified in ORF2 of GAstV-1. • mAb-based ELISA and IFA for detection of GAstV-1 were developed.

Epidemiological investigation and genetic characterization of porcine astrovirus genotypes 2 and 5 in Yunnan province, China

Astroviruses (AstVs) are among the most important viruses causing diarrhea in human infants and many animals, posing a threat to public health safety and a burden on the economy. Five porcine AstV (PAstV) genotypes have been identified in various countries, including China. However, the epidemiology of PAstV in Yunnan province, China, remains unknown. In this study, 489 fecal samples from pigs in all 16 prefectures/cities of Yunnan were collected between April and August of 2020 for epidemiological investigation. The total infection rate of PAstV-2 or PAstV-5 was 39.9%, with suckling piglets having the highest infection rate (62.3%). The ORF2 genes of seven PAstV-2 and 10 PAstV-5 isolates were sequenced and phylogenetically analyzed. In addition to coinfections with PAstV-2 and PAstV-5, coinfections of PAstV with other diarrhea-inducing viruses (e.g., porcine bocavirus) were also discovered. A comparison of ORF2-encoded capsid protein sequences revealed that there were multiple insertions and deletions in the seven Yunnan PAstV-2 sequences, while point mutations, but no deletions or insertions, were found in the 10 Yunnan PAstV-5 sequences, which were very similar to the reference sequences. This is the first epidemiological investigation and genetic characterization of PAstV-2 and PAstV-5 in Yunnan province, China, demonstrating the current PAstV infection situation in Yunnan.

Identification of novel B-cell epitopes on the capsid protein of type 1 porcine astrovirus, using monoclonal antibodies

Porcine astrovirus (PAstV) is prevalent in pigs worldwide and could cause clinical symptoms such as diarrhea and encephalitis. The capsid protein (Cap) of PAstV plays a determinant role for virus immunological characteristics. In this study, the major antigenic regions of PAstV1 Cap were expressed through prokaryotic expression systems and immunized to BALB/c mice. Finally, two anti-Cap monoclonal antibodies (named mAb F4-4 and D3F10) were screened by indirect immune-fluorescence assay (IFA). A series of truncated GST-fused or artificially synthesized peptides were used to detect their reactivity with the mAbs and PAstV positive serum. Two novel B cell epitopes (120-GNNTFG-125, 485-RISDPTWFSA-494) were identified by using these two mAbs. Moreover, sequence alignment result showed that epitope 120-GNNTFG-125 was highly conserved in type 1 PAstV capsid protein. Cross-reactivity analysis further confirmed the genotype-specificity of mAb F4-4. The results of this study demonstrated to be the first description of monoclonal antibody preparation and B-cell epitope mapping on PAstV capsid protein, which may provide new information on the biological significance of PAstV capsid protein and lay a foundation for the development of PAstV immunological tests and genotype diagnostic methods.

Insertion of Exogenous Genes within the ORF1a Coding Region of Porcine Astrovirus

A tagged or reporter astrovirus can be a valuable tool for the analysis of various aspects of the virus life cycle, and to aid in the development of genetically engineered astroviruses as vectors. Here, transposon-mediated insertion mutagenesis was used to insert a 15-nucleotide (nt) sequence into random sites of open reading frame 1a (ORF1a) based on an infectious full-length cDNA clone of porcine astrovirus (PAstV). Five sites in the predicted coiled-coil structures (CC), genome-linked protein (VPg), and hypervariable region (HVR) in ORF1a of the PAstV genome were identified that could tolerate random 15 nt insertions. Incorporation of the commonly used epitope tags, His, Flag, and HA, into four of the five insertion sites permitted the production of infectious viruses and allowed recognition by specifically tagged monoclonal antibodies. The results of immuno-fluorescent assays showed that Flag-tagged ORF1a protein overlapped partially with capsid and ORF2b proteins in the cytoplasm. Improved light-oxygen-voltage (iLOV) gene was also introduced at the insertion sites of CC, VPg, and HVR. Only one viable recombinant reporter PAstV expressing iLOV inserted in HVR was recovered. Biological analysis of the reporter virus showed that it displayed similar growth characteristics, and yet produced less infectious virus particles, when compared with the parental virus. The recombinant virus carrying the iLOV fused with the HVR of ORF1a protein maintained its stability and showed green fluorescence after 15 passages in cell cultures. The resultant fluorescently tagged virus could provide a promising tool for the rapid screening of antiviral drugs as well as allowing the visualization of PAstV infection and replication in living cells.

Isolation and characterization of a duck-origin goose astrovirus in China

In 2019, a new type of infectious disease characterized with haemorrhage and swellings of kidneys, occurred on commercial duck farms in Shandong province, China. Our systematic investigation led to the isolation of an astrovirus, designated AstV-SDTA strain and was isolated from a diseased duckling using LMH cells. Similar clinical symptoms were reproduced by experimental infection using the AstV-SDTA strain. The complete genome sequencing characterization of AstV-SDTA was conducted using next-generation sequencing (NGS) technique on Illumina HiSeq platform, and used polymerase chain reaction method to verify the NGS results for the obtained whole sequences. Phylogenetic analysis revealed that AstV-SDTA strain belongs to a novel goose astrovirus (GoAstV) branch of avian astroviruses, and the nucleotide homology based on the complete genome sequences among AstV-SDTA and other GoAstV strains deposited in Genbank was 97.2–98.8%. Taken together, these results suggest that the cross-species transmission of novel GoAstV between domestic waterfowl is possible. Further surveillance of novel GoAstV in poultry are needed in order to gain a better understanding of both the molecular and evolutionary characteristics of novel GoAstV.

Pathogenicity of novel goose-origin astrovirus causing gout in goslings

Background

A novel goose-origin astrovirus (GoAstV) has broken out across China in recent years, causing gout in goslings with a mortality rate of around 50%. However, our understanding of the dynamic distribution, tissue tropism and pathogenesis of GoAstV is incomplete. In order to assess its pathogenicity, one-day-old goslings were inoculated separately with GoAstV via oral and subcutaneous injection routes.

Results

Clinical symptoms, gross and microscopic lesions, blood biochemical parameters and viral loads were detected and recorded for 20 days after infection. Typical gout was observed in experimental goslings. GoAstV can be replicated in tissues and cause pathological damage, especially in the kidney, liver, heart and spleen. Virus-specific genomic RNA was detected in blood, cloacal swabs and all representative tissues, and virus shedding was detected up to 20 days after inoculation, suggesting that GoAstV has a wide tissue tropism and spread systematically after inoculation. The viral copy numbers examined in kidney were the highest, followed by spleen and liver.

Conclusion

This experiment determined the accurate value of viral loads and biochemical indicators of GoAstV-induced goslings. These findings increase our understanding of the pathogenicity of GoAstV in goslings and provide more reference for future research.

Identification of a novel protein in porcine astrovirus that is important for virus replication

Overlapping genes are common in some RNA viruses. It has been proposed that a potential overlapping gene is the ORFX, here termed ORF2b, which overlaps the ORF2 coding sequence in astroviruses. The aim of this study was to determine whether ORF2b is an overlapping gene that encodes a functional protein which is needed for viral replication. Sequence alignment showed that there was an ORF2b in a PAstV type 1 strain of astrovirus, PAstV1-GX1, which was embedded within the larger ORF2. The AUG codon for ORF2b is located 19 nucleotides downstream of the initiation site of ORF2 and contains 369 nucleotides and it codes for a predicted 122-amino-acid protein. A specific polyclonal antibody against the ORF2b protein was raised and used to demonstrate the expression of the new identified gene in virus-infected and pCAGGS-ORF2b-transfected cells. Analysis of purified virions revealed that the ORF2b protein was not incorporated into virus particles. Reverse genetics based on a PAstV type 1 infectious cDNA clone showed that the ORF2b protein was not essential but important for optimal virus infectivity. Knockout of the downstream potential stop codon candidate of ORF2b demonstrated that the C-terminus of the ORF2b protein can be extended by 170 amino acids, suggesting that the C-terminus of the newly identified ORF2b protein may be variable.

Isolation and Characterization of Porcine Astrovirus 5 from a Classical Swine Fever Virus-Infected Specimen

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.

OASL Triggered by Novel Goose Astrovirus via ORF2 Restricts Its Replication

Although astroviruses causes enteric diseases and encephalitis in humans and nephritis and hepatitis in poultry, astrovirus infection is thought to be self-limiting. However, little is known about its molecular mechanism. In this study, we found that a novel goose astrovirus (GAstV), GAstV-GD, and its open reading frame 2 (ORF2) could efficiently activate the innate immune response and induce a high level of OASL in vitro and in vivo The truncation assay for ORF2 further revealed that the P2 domain of ORF2 contributed to stimulating OASL, whereas the acidic C terminus of ORF2 attenuated such activation. Moreover, the overexpression and knockdown of OASL could efficiently restrict and promote the viral replication of GAstV-GD, respectively. Our data not only give novel insights for elucidating self-limiting infection by astrovirus but also provide virus and host targets for fighting against astroviruses.IMPORTANCE Astroviruses cause gastroenteritis and encephalitis in human, and nephritis, hepatitis, and gout disease in poultry. However, the host immune response activated by astrovirus is mostly unknown. Here, we found that a novel goose astrovirus, GAstV-GD, and its ORF2 protein could efficiently induce a high level of OASL in vitro and in vivo, which could feed back to restrict the replication of GAstV-GD, revealing novel innate molecules triggered by astroviruses and highlighting that the ORF2 of GAstV-GD and OASL can be potential antiviral targets for astroviruses.

Astrovirus reverse genetics systems, a story of success

Astroviruses are one of the main causes of gastroenteritis of medical and veterinary relevance worldwide. Recently, these viruses were associated with neurological disease in mammals, including humans. Reverse genetics systems are the most powerful tool to improve our understanding of the virus replication, and eventually to develop safe vaccine candidates. In the present review, it is summarized the current knowledge on the different strategies used to develop reverse genetics systems for mamastroviruses and avastroviruses, and some of the biological answers that have provided are discussed.

Pathogenic Characteristics of a Porcine Astrovirus Strain Isolated in China

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.

An emerging novel goose astrovirus associated with gosling gout disease, China

Since the first isolation from human, astroviruses have been detected in many species. Wide host range and occasional cross-transmission of astrovirus pose a risk for zoonotic infection. Here, novel astroviruses were identified from goslings with recent epidemic gout disease in China. A virus, designated as GD, was efficiently isolated from a diseased gosling using LMH cells. Genome of GD amplified using 5′ and 3′ RACE was 7183nt in full length. Sequence analysis revealed the genome of GD was <60.8% homology with others deposited in Genbank. Moreover, GD could be neutralized by goose convalescent sera, and the gout associated symptom in goslings could be reproduced by GD infection. Our data demonstrated the goose astrovirus could be one of the causative agents of the ongoing gosling gout disease in China. The identification of the goose astrovirus not only diversified the astrovirus species, but also broadened the disease patterns caused by astroviruses.