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Avian nephritis virus (ANV), which belongs to the Astroviridae family, has been associated with acute nephritis in chickens. Cases of ANV infection have been recorded in Japan and in several European countries. However, related studies have never been performed in China. Thus, this study isolated ANV in Chinese chicken flocks. ANV RNA was detected by reverse transcription–PCR in stool samples collected from healthy layer chickens in the Sichuan Province of China in 2009. Of the 192 stool specimens collected, 32.3% (62/192) were positive for ANV infection. The whole genome of ANV-Sichuan54, the first representative Chinese strain, was 6941 nucleotides in length, including the 5′ untranslated region, three open reading frames (ORFs), a 3′ UTR, and a poly-(A) tail. Comparative and phylogenetic analyses based on partial RNA-dependent RNA polymerase (ORF1b) demonstrated that the majority of ANV investigations were more closely related to the U.S. ANV strain (DQ324827–324836) than to the G-4260 (AB033998).

Infectious diseases are a major obstacle to profitable poultry production in Nigeria due to the mortality and severe economic losses they cause. In particular, they are a potent threat to attainment of the food security goals of government and national self-sufficiency in food production. Thus, there is a need for continuous monitoring of the nation’s poultry population for these diseases. As part of an ongoing investigation of enteric viruses associated with poor performance or hatchery diseases in commercial poultry in southwestern Nigeria, intestinal contents from 97 condemned or runted day-old commercial turkey poults were examined for turkey astroviruses, infectious bronchitis virus, chicken astrovirus (CAstV), avian nephritis virus, avian rotavirus, avian reovirus, fowl adenovirus, and chicken parvovirus by virus isolation, electron microscopy (EM), polymerase chain reaction (PCR), and reverse transcription PCR. The samples were collected from five commercial hatcheries and five farms located in southwestern Nigeria. While all samples tested negative for other viruses, CAstV was detected in the majority (83.5%) of the birds, although some pleomorphic virus-like particles with surface projections that appeared fringed or fimbriated were observed in five of the cell culture samples by EM. Phylogenetic analysis revealed these CAstV strains belonged to the Bi clade. These findings not only implicate CAstV as the major cause of hatchery condemnations in commercial turkeys in southwestern Nigeria but also highlight the need for experimental studies to further establish its role in this disease condition.

The enteric chicken astrovirus (CAstV) and avian nephritis virus (ANV) are the type species of the genus Avastrovirus (AAstV; Astroviridae family), capable of causing considerable production losses in poultry. Using next-generation sequencing of a cloacal swab from a backyard chicken in Tanzania, we assembled genome sequences of ANV and CAstV (6918 nt and 7318 nt in length, respectively, excluding poly(A) tails, which have a typical AAstV genome architecture (5′-UTR-ORF1a-ORF1b-ORF2-‘3-UTR). They are most similar to strains ck/ANV/BR/RS/6R/15 (82.72%) and ck/CAstV/PL/G059/14 (82.23%), respectively. Phylogenetic and sequence analyses of the genomes and the three open reading frames (ORFs) grouped the Tanzanian ANV and CAstV strains with Eurasian ANV-5 and CAstV-Aii viruses, respectively. Compared to other AAstVs, the Tanzanian strains have numerous amino acid variations (substitutions, insertions and deletions) in the spike region of the capsid protein. Furthermore, CAstV-A has a 4018 nt recombinant fragment in the ORF1a/1b genomic region, predicted to be from Eurasian CAstV-Bi and Bvi parental strains. These data should inform future epidemiological studies and options for AAstV diagnostics and vaccines.

Avian nephritis virus (ANV) infection is associated with diarrhea, uricosis, stunting, tubulonephrosis, interstitial nephritis, and mortality of chicken flocks, leading to economic losses in the poultry industry. In this study, an ANV strain designated as HNU-ANV-ML-2020 was identified in tissue samples collected from chickens with severe enteritis on a poultry farm in Hunan province, China, and analyzed. The genome of HNU-ANV-ML-2020 is 6943 nucleotides in length. It showed the highest sequence identity (88.1%) to ANV strain CHN/GXJL815/2017 (MN732559) from Guangxi province, China, while it showed less than 86% identity to other astrovirus (AstV) genome sequences available in the GenBank database. The capsid protein of this virus showed the highest sequence identity to ANV strains HQ330482 and HQ330498 from the UK (81.2% and 81.06%, respectively), while it showed only 73.9% identity to MN732559 and less than 80% identity to the capsid proteins of other AstVs available in GenBank. Further phylogenetic analysis demonstrated that HNU-ANV-ML-2020 belongs to group 4, together with ANV strains identified in Australia, Brazil, the UK, and the Netherlands. Furthermore, ANV strains identified in chickens in China were found to be separated into four distinct groups/genotypes, indicating substantial genetic divergence and a complex circulation pattern in China. The virus characterized in the present study is a novel ANV variant identified for the first time in Hunan province, China.

Background Enteric viruses are among the most prominent etiological agents of Runting-Stunting Syndrome (RSS). The Avian Nephritis Virus (ANV) is an astrovirus associated with enteric diseases in poultry, whose early diagnosis is essential for maintaining a good poultry breeding environment. ANV is an RNA virus that rapidly mutates, except for some conserved regions such as ORF1b. Therefore, the approach of a diagnostic method based on fast-RT-qPCR using SYBR® Green that focuses on the amplification of a fragment of ORF1b is presented as a feasible alternative for the diagnosis of this viral agent. In this study, the proposed assay showed a standard curve with an efficiency of 103.8% and a LoD and LoQ of 1 gene viral copies. The assay was specific to amplify the ORF 1b gene, and no amplification was shown from other viral genomes or in the negative controls. 200 enteric (feces) samples from chickens (broilers) and laying hens with signs of RSS from Ecuadorian poultry flocks were examined to validate the proposed method. Results Using our method, 164 positive results were obtained out of the total number of samples run, while the presence of viral RNA was detected in samples collected from one day to 44 weeks old in both avian lines. Conclusions Our study presents a novel, rapid, robust, and sensitive molecular assay capable of detecting and quantifying even low copy numbers of the ANV in commercial birds, therefore introducing a handy tool in the early diagnosis of ANV in enteric disease outbreaks in poultry.

Intestinal samples collected from 43 commercial broiler and 33 commercial turkey flocks from all regions of the United States during 2005 and 2006 were examined for the presence of astrovirus, rotavirus, reovirus, and coronavirus by reverse transcription-polymerase chain reaction (PCR), and for the presence of groups 1 and 2 adenovirus by PCR. Phylogenetic analysis was performed to further characterize the viruses and to evaluate species association and geographic patterns. Astroviruses were identified in samples from 86% of the chicken flocks and from 100% of the turkey flocks. Both chicken astrovirus and avian nephritis virus (ANV) were identified in chicken samples, and often both viruses were detected in the same flock. Turkey astrovirus type-2 and turkey astrovirus type-1 were found in 100% and 15.4% of the turkey flocks, respectively. In addition, 12.5% of turkey flocks were positive for ANV. Rotaviruses were present in 46.5% of the chicken flocks tested and in 69.7% of the turkey flocks tested. Based upon the rotavirus NSP4 gene sequence, the chicken and turkey origin rotaviruses assorted in a species-specific manner. The turkey origin rotaviruses also assorted based upon geographical location. Reoviruses were identified in 62.8% and 45.5% of chicken and turkey flocks, respectively. Based on the reovirus S4 gene segment, the chicken and turkey origin viruses assorted separately, and they were distinct from all previously reported avian reoviruses. Coronaviruses were detected in the intestinal contents of chickens, but not turkeys. Adenoviruses were not detected in any chicken or turkeys flocks. Of the 76 total chicken and turkey flocks tested, only three chicken flocks were negative for all viruses targeted by this study. Most flocks were positive for two or more of the viruses, and overall no clear pattern of virus geographic distribution was evident. This study provides updated enteric virus prevalence data for the United States using molecular methods, and it reinforces that enteric viruses are widespread in poultry throughout the United States, although the clinical importance of most of these viruses remains unclear.

Avian nephritis virus (ANV) is classified in the Avastroviridae family with disease associations with nephritis, uneven flock growth and runting stunting syndrome (RSS) in chicken and turkey flocks, and other avian species. The whole genome of ANV genotype 3 (ANV-3) of 6959 nucleotides including the untranslated 5′ and 3′ regions and polyadenylated tail was detected in a metagenomic virome investigation of RSS-affected chicken broiler flocks. This report characterises the ANV-3 genome, identifying partially overlapping open reading frames (ORFs), ORF1a and ORF1b, and an opposing secondary pseudoknot prior to a ribosomal frameshift stemloop structure, with a separate ORF2, whilst observing conserved astrovirus motifs. Phylogenetic analysis of the Avastroviridae whole genome and ORF2 capsid polyprotein classified the first complete whole genome of ANV-3 within Avastroviridae genogroup 2.

Enteric viruses play an important role in the Brazilian poultry industry due to the economic impact of resulting low yields of broilers, layers, and breeders. The most common enteric viruses affecting commercial flocks in Brazil include Fowl Adenovirus of group I (FAdV-I), Chicken Parvovirus (ChPV), Chicken Astrovirus (CAstV), Avian Nephritis Virus (ANV), Infectious Bronchitis Virus (IBV), Avian Reovirus (AReo), and Avian Rotavirus (ARtV). The aim of this study was to identify single and multiple infections using data obtained from 270 samples from eleven Brazilian states, corresponding to the period between 2010 and 2017. This was accompanied by an analysis of the relationship between the age of birds, clinical signs, and geographical distribution, using Polymerase Chain Reaction (PCR) and Reverse Transcription-PCR (RT-PCR) techniques. Twenty-five profiles of virus combinations were detected. Single infections were encountered in 86.3% of samples, and multiple infections were present in the remaining 13.7%. Both single and multiple infections affected all kinds of commercial chickens with digestive problems, stunting syndrome, decreases in egg and meat production, increased mortality, and respiratory signs. FAdV-I, ChPV, CAstV, ANV, and ARtV were mostly detected in young broilers, in contrast with IBV, which was detected in hens from one to greater than 51 weeks of age. These results exhibit the complexity of enteric diseases and the still poorly understood role of each pathogen as a unique etiological agent.

Chicken astrovirus (CAstV) and avian nephritis virus (ANV) are enteric viruses of poultry and have infected a wide range of poultry species worldwide, causing runting-stunting syndrome (RSS), which requires virus screening and results in serious economic damage. No confirmed cases have been reported from Bangladesh. In the present study, CAstV and ANV were monitored in Bangladesh. We monitored samples for CAstV and ANV and compared their genomic sequences to other reference strains. We found 8/31 flocks (25.8%) were positive for CAstV, 6/31 flocks (19.3%) had mixed infection of CAstV and ANV, and 1 flock (3.2%) was positive for ANV. Only ANV and a combination of CAstV and ANV were found in broilers and broiler breeders, but CAstV was found in all types of chickens. We isolated two of each from CAstV and ANV through specific pathogen-free chicken embryonated eggs via the yolk sac route. Phylogenetic analysis based on the ORF1b conserved region of CAstV and ANV suggested that the locally circulating strain was closely related to the strains isolated from India and Brazil. This report is the first molecular characterization of CAstV and ANV in Bangladesh. This study highlights that CAstV and ANV are circulating in Bangladeshi poultry.

Astroviruses are frequently associated with enteric diseases in poultry, being isolated from cases of runting-stunting syndrome (RSS) of broiler chickens, poult enteritis complex (PEC), and poult enteritis mortality syndrome (PEMS) of turkeys. Currently, five types of avian astrovirus have been identified: turkey astroviruses 1 and 2 (TAstV-1, TAstV-2), avian nephritis virus (ANV), chicken astrovirus (CAstV) and duck astrovirus (DAstV). The objective of this study was to molecularly characterize the different types of avian astroviruses circulating in commercial poultry. Sequence analysis of a region of ORF2, which encodes the capsid precursor protein associated with serotype and viral pathogenesis, revealed extensive variation in amino acid sequence within each subtype: TAstV-2 (81.5%-100%), ANV (69.9%-100%), and CAstV (85.3%-97.9%). However, this region was more conserved in TAstV-1's (96.2%-100%). Furthermore, a novel astrovirus was detected in chicken samples and found to be <64% similar to ANV and <30.6% similar to CAstV. The results of this study underline the great genetic variability of avian astroviruses and indicate that there are most likely multiple serotypes of each avian astrovirus circulating in commercial poultry.