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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.

Outbreaks of fowl adenoviruses (FAdVs) infection with the main clinical signs of hepatitis-hydropericardium-syndrome or inclusion body hepatitis have been frequently reported in ducks and geese in recent years, causing economic losses for the Chinese waterfowl industry. This study investigated 792 samples (391 fattening ducks, 192 breeder ducks and 209 fattening geese) of suspected FAdV-infected waterfowl from 38 farms (21 fattening duck farms, nine breeder duck farms and eight fattening geese farms) in Shandong Province between 2019 and 2022. The results showed a 60.23% infection rate for FAdVs (477/792), while the infection rate for breeder ducks was almost the same as that for fattening geese (55.73% vs. 54.55%). Notably, co-infection with avian influenza virus H9N2 (H9N2), Tembusu virus (TMUV), duck hepatitis virus (DHV), duck circovirus (DuCV), goose astrovirus (GAstV) and duck parvovirus (DPV)/goose parvovirus (GPV) was common among the 477 FAdVs positive cases. Phylogenetic analysis of complete hexon genes of 22 FAdV strains in Shandong Province showed the presence of four species (FAdV-A, C, D, E) and five serotypes (FAdV-1, 4, 8a, 8b, 11). These findings provide the first data on the prevalence and co-infection status of FAdVs in Shandong Province and can be used as a basis for FAdV prevention in the field. Samples of suspected FAdV-infected waterfowl from farms in Shandong Province were collected from 2019 to 2022. Single infections with FAdV were less frequent than mixed infections. 477 out of 792 samples (60.23%) tested positive for FAdV nucleic acids. Detection rate of FAdV was 65.47% in fattening duck farms, 55.73% in breeder duck farms and 54.55% in fattening geese farms. [ABSTRACT FROM AUTHOR]

Geese play an important role in agricultural economics, with China producing the vast majority of goose meat consumed worldwide annually. The variations in the avian viruses and co‐infections result in substantial economic losses to the goose industry in China. To understand the evolutionary characteristics and co‐infections of viruses, a broad epidemiological investigation of epizootic viruses of goose was carried out in nine provinces of China during 2018–2021. Here, the results indicated that, among the 1970 clinical samples, 50.81% (1001/1970) were positive for goose astrovirus (GAstV), 18.22% (359/1970) for avian orthoreovirus, 12.74% (251/1970) for goose parvovirus, 11.02% (217/1970) for H9N2 subtype avian influenza virus, 4.01% (79/1970) for Newcastle disease virus, and 2.08% (41/1970) for fowl adenovirus. Among the six viruses, co‐infections comprised a large proportion (66.37%) in the field, of which the dual infection was more common. Additionally, phylogenetic analysis of GAstVs indicated that Chinese GAstVs had formed two distinct groups, that is, GAstV‐1 and GAstV‐2. GAstV‐2 sub‐genotype II‐c had arisen as the dominant genotype in the whole country. Notably, all the H9N2‐AIV isolated strains harboured the mammalian adaptation markers I155T, H183N, and Q226L (H3 numbering) in the HA gene, which promotes preferential binding to human‐like α2‐6‐linked sialic acid receptors. And beyond that, we determined that the goose‐origin Muscovy Duck Reovirus isolates, showing 51.7%–96% similarities to that of other waterfowl‐origin orthoreovirus isolates in sequence homology analysis of the representative part of σC, are a new variant of waterfowl‐origin orthoreovirus. These data provide valuable information about the prevalence of infectious diseases in geese on mainland China. [ABSTRACT FROM AUTHOR]

Duck circovirus (DuCV) is one of the most prevalent infectious viruses in the duck industry in China. Although the clinical signs vary, it often causes immunosuppression in the host and leads to secondary infection with other pathogens. Novel goose parvovirus (NGPV) mainly infects ducks and causes short beak and dwarfism syndrome in ducks. However, the incidence of infection in ducks has increased in recent years, and the phenomenon of mixed infection with DuCV is common, resulting in more severe clinical morbidity. However, there are no systematic studies evaluating the presence of mixed infections. In order to investigate the synergistic pathogenicity of DuCV and NGPV co-infection in SPF ducks, a comparative experiment using DuCV and NGPV co-infection and mono-infection bird models was established. The results showed that the clinical signs of short beak, dwarfism and immunosuppression were more obvious in DuCV and NGPV co-infected ducks; the tissue damage of target organs was more serious, and the viral titre in organs and cloacal swabs were more significant compared with those of SPF ducks infected with only one virus. The results indicated that co-infection with DuCV and NGPV could promote viral replication and cause more severe tissue damage and immunosuppression than single virus infection. The present study reveals that the co-infection of NGPV and DuCV has a synergistic pathogenic effect from the aspect of pathogenicity, and the conclusions drawn not only clarify the direction of the subsequent research on the mechanism of co-infection of NGPV and DuCV, but also provide a scientific basis for the research on the co-infection of immunosuppressive pathogens and other pathogens. [ABSTRACT FROM AUTHOR]

Goose astrovirus genotype 2 (GAstV-2) is the causative agent causing severe visceral gout and joint gout in goslings, with mortality rates of affected flocks up to 50%. To date, continuous GAstV-2 outbreaks still pose a great threat to goose industry in China. Although most researches on GAstV-2 have focused on its pathogenicity to geese and ducks, limited studies have been performed on chickens. Herein, we inoculated 1-day-old specific pathogen-free (SPF) White Leghorn line chickens with 0.6 mL of GAstV-2 culture supernatant (TCID 50 10−5.14/0.1 mL) via orally, subcutaneously and intramuscularly, and then assessed the pathogenicity. The results revealed that the infected chickens presented depression, anorexia, diarrhea, and weight loss. The infected chickens also suffered from extensive organ damage and had histopathological changes in the heart, liver, spleen, kidney, and thymuses. The infected chickens also had high viral load in tissues and shed virus after the challenge. Overall, our research demonstrates that GAstV-2 can infect chickens and adversely affect the productivity of animals. And the viruses shed by infected chickens can pose a potential risk to the same or other domestic landfowls. [ABSTRACT FROM AUTHOR]

Goose astrovirus (GAstV) characterized by articular and visceral gout, is an emerging pathogen with a wide distribution on mainland China, leading to serious economic losses in the goose-raising industry. Because vaccines to prevent GAstV infections are not available currently, early diagnosis is critical when treating symptomatic geese and in preventing GAstV transmission. In this context, a highly sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a monoclonal antibody (mAb) to detect GAstV-specific antibodies from geese was developed, and the detections were optimized. A series of experiments proved that the ic-ELISA shows excellent diagnostic performance and discriminatory power with high sensitivity and specificity. The ic-ELISA for GAstV detection was applied on 67 field serum samples, and comparing the detection results with the virus neutralization test verified the accuracy of the ic-ELISA. The correlation coefficient between the ic-ELISA and the virus neutralization test was 80%, demonstrating the proposed ic-ELISA method could be a useful and effective tool for the diagnostic, serological epidemiological investigation and immune monitoring of the GAstV in goose-producing regions. • A competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect GAstV-specific antibodies was developed. • The ic-ELISA assay is sensitive, reliable and reproducible. • The ic-ELISA assay could be a tool for the serological epidemiological investigation of the GAstV in goose-producing regions. [ABSTRACT FROM AUTHOR]