Genome analysis of newly emerging goose-origin nephrotic astrovirus in China reveals it belongs to a novel genetically distinct astrovirus.

Since 2017, a new type of goose-origin astrovirus (GoAstV) disease occurred in China. This disease can cause joint swelling of sick geese, and the anatomy shows a clear urate precipitation in the viscera. The rate of death or amputation can reach more than 30%, revealing its severe pathogenicity. One novel goose-origin astrovirus strain, designated as CXZ18, was isolated from diseased geese with a fatal infection characterized by visceral urate deposition. Similar clinical anatomy symptoms were partially reproduced by attacking infection of healthy geese. The CXZ18 has no hemagglutination with chicken erythrocyte, only reproduced in goose embryos, not in SPF chicken or duck embryos. The complete genome-encoded three open reading frames (ORFs) of CXZ18 were 7252 nt in length. BLAST-based homology analysis of viral complete genome showed that CXZ18 has only 53.0%-61.8% with other classic avian astrovirus from various hosts. Further analysis of ORF 1a, ORF 1b, and ORF 2 genes revealed that the isolate was genetically distinct from known astroviruses and belonged to a distinctive branch of avian astroviruses. To conclude, a naturally occurring novel nephrotic astrovirus, distinguished with all previously reported avian astroviruses, was derived from goose.

Isolation of chicken astrovirus from specific pathogen-free chicken embryonated eggs.

Astroviruses have been associated with enteric disorders in many animal species, including chickens. Here, we describe the isolation, propagation, and pathological characteristics of chicken astrovirus (CAstV) in specific pathogen free (SPF) chicken embryonated eggs (CEE) from chickens with diarrhea and runting-stunting syndrome. The CEE were inoculated via the yolk sac route. Viral confirmation was carried out using PCR techniques and transmission electron microscopy negative staining with ammonium molybdate. The intestinal contents were screened for CAstV, and differential diagnostic testing was performed for avian nephritis virus, avian rotavirus, avian reovirus, chicken parvovirus, infectious bronchitis virus, and fowl adenovirus Group I to detect co-infection with other infectious agents. Seven- or 14-day-old CEEs presented with hemorrhages, edema, a gelatinous aspect, deformities, and dwarfism. The supporting membranes did not show any alterations. Here, we have described the isolation of CAstV and its pathological characteristics in SPF CEE.

Co-circulation of distinct genetic lineages of astroviruses in turkeys and guinea fowl.

Viruses belonging to the genus Astrovirus have been increasingly associated with enteritis in mammalian and avian species, including turkeys. More recently, astroviruses have also been detected in diseased guinea fowl. In turkeys, two genetically distinct types of astrovirus have been reported, namely turkey astrovirus 1 and 2 (TAstV1 and TAstV2). The prevalence and the pathogenesis of astrovirus infections in this species is currently unknown, with the exception of data generated in the USA. In the present report, we have demonstrated the co-circulation of distinct genetic lineages of astroviruses infecting turkeys and guinea fowl. The predominant lineage infecting turkeys is genetically related to the American TAstV2, but genetic variability within this lineage was demonstrated. Other isolates appeared to be either TastV1-related or unrelated to any other known isolate. Astroviruses infecting guinea fowl were more closely related to TAstV2, and interspecies transmissions between turkeys and guinea fowl is suggested as a possible mechanism by which these viruses may have evolved, based on the genetic data available. This investigation provides genetic and epidemiological information contributing to a better understanding of enteric viral infections in turkeys and guinea fowl.