The first detection of avian nephritis virus (ANV) in goose embryos and of turkey astrovirus-1 (TAstV-1) in duck embryos is described. Intestinal samples from duck and goose embryos from five duck and four goose flocks in Croatia were tested by polymerase chain reaction for the presence of ANV, TAstV-1, turkey astrovirus-2, chicken astrovirus, duck astrovirus and also for the presence of avian reovirus, Derzsy's disease virus and duck enteritis virus. The kidneys from duck and goose embryos were also tested for ANV, while liver samples were tested for duck astrovirus. Duck embryos were also tested to detect duck circovirus and goose embryos for the presence of goose circovirus and goose haemorrhagic polyomavirus. All embryos were in the final stage of incubation and were characterized by moderate to markedly retarded growth. ANV was confirmed in the intestines and kidneys of embryos from two duck and two goose flocks and TAstV-1 was found in embryos from two duck flocks. One duck flock was positive for both ANV and TAstV-1. No other viruses were found in tested flocks. Phylogenetic analysis based on the ANV polymerase gene fragment of ANV sequences detected in duck and goose embryos revealed greatest similarity (88.1 to 97.2%) with ANV isolates from chickens. Further, the existence of at least two types of ANV circulating in Croatian duck and goose flocks was confirmed. Based on the phylogenetic analysis of the portion of TAstV-1 polymerase gene, two detected TAstV-1 nucleotide sequences were 99.5% similar. Compared with six TAstV-1 sequences, Croatian sequences showed one unique nucleotide change. In addition to other possible causes of stunted growth and late embryonic death, these findings suggest that ANV and/or TAstV-1 infection may be a contributing factor in the pre-hatching mortality of ducklings and goslings.

The natural occurrence of chicken and turkey-origin astroviruses in domestic ducks (Anas platyrhynchos domesticus) is described. Twenty-two duck flocks were covered by this research. The liver, spleen, kidney and intestines were sampled and tested by reverse-transcription polymerase chain reaction for the presence of avian nephritis virus (ANV), chicken astrovirus (CAstV), turkey astrovirus (TAstV)-1, TAstV-2 and duck astrovirus. The astrovirus infection was confirmed in multiple organ samples from 59.1% of tested flocks. CAstV was detected in one flock, TAstV-2 in three flocks and ANV in 10 flocks. The molecular and phylogenetic analysis of the small open reading frame (ORF) 1b fragment (130 nucleotides) of all chicken and turkey-origin astroviruses detected in ducks showed that ANV-sequence group was more distant from CastV, TAstV-1 and TAstV-2 sequences, which formed a separate, more related group. ANV sequences were divided into three subgroups, suggesting that several types of ANV were circulating in Croatian duck flocks. The comparison of the partial ORF 1b (254 nucleotides) duck ANV sequences with 21 ANVs detected in various avian species (chickens, turkeys, geese, guinea fowl and pigeons) revealed they shared the higher nucleotide (95.6 to 97.2%) and amino acid (98.8 to 100%) identity with two ANV-2-like sequences from chickens (GA-SEP-A451-05 and GA-CK-SEP ANV-364-2005). Phylogenetic neighbour-joining tree analysis based on the same nucleotide alignment, and performed using the Jukes-Cantor method, clustered the compared sequences into three groups. All analysed duck ANV sequences showed a close phylogenetic relationship with chicken-origin ANVs. Additional work is required to determine the significance and pathogenicity of chicken and turkey-origin astroviruses in domestic ducks.

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Phylogenetic diversity of parvovirus detected in commercial chicken and turkey flocks is described. Nine chicken and six turkey flocks from Croatian farms were tested for parvovirus presence. Intestinal samples from one turkey and seven chicken flocks were found positive, and were sequenced. Natural parvovirus infection was more frequently detected in chickens than in turkeys examined in this study. Sequence analysis of 400 nucleotide fragments of the nonstructural gene (NS) showed that our sequences had more similarity with chicken parvovirus (ChPV) (92.3%-99.7%) than turkey parvovirus (TuPV) (89.5%-98.9%) strains. Phylogenetic analysis grouped our sequences in two clades. Also, the higher prevalence of ChPV than TuPV in tested flocks was defined. The necropsy findings suggested a malabsorption syndrome followed by a preascitic condition. Further research of parvovirus infection, pathogenesis, and the possibility of its association with poult enteritis and mortality syndrome (PEMS) and runting and stunting syndrome (RSS) is needed to clarify its significance as an agent of enteric disease.

The first evidence of avian nephritis virus (ANV) in ducks is described. A diagnostic investigation was performed on three duck farms in Croatia. Samples from dead-in-shell ducklings and ducklings aged 30 days were collected and prepared for molecular and histopathological examination. Intestinal and liver samples were tested by polymerase chain reaction (PCR) for the presence of ANV, duck enteritis virus, duck hepatitis virus 1 and Derzsy's disease virus. Multiple tissues were collected for histological examination and lesions were found to be confined to the kidney and intestine. Moderate focal interstitial and periglomerular mononuclear cell infiltrates (mostly lymphocytes and plasma cells) were detected in the kidney. The duodenum showed rather diffuse pericryptal mononuclear cell hyperplasia (lymphocytes) and fibroplasia. ANV was detected by PCR in all the intestinal samples, while no other viruses were found. Sequence comparisons of the portion of the open reading frame 1b encoding the RNA-dependent RNA polymerase gene confirmed that the virus detected and sequenced from ducklings shared high nucleotide and amino acid identities with ANV-1. Additional work is required to determine the clinicopathological significance of ANV infection in ducks.