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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.

Rotavirus A infects many mammalian species, including humans and causes diarrhea and gastrointestinal diseases. The virus also infects various bird species, including chickens, although information of avian rotavirus A (ARVA) infection in chicken populations in Japan is scarce. In this study, we report for the first time the whole-genome sequences of ARVA strains from Japanese chicken populations. The virus strains were inoculated to MA104 cells and cultured viruses were used to obtain the sequences with the MiSeq system, and genetic analysis demonstrated the genotype constellation of G19-P[30]-I11-R6-C6-M7-A16-N6-T8-E10-H8 of the Japanese chicken ARVA isolates. Phylogenetic analyses demonstrated that the VP1, VP2, VP3, VP4, VP7, NSP2, and NSP4 coding gene sequences of the Japanese strains were closer to those of Korean than the European ARVA strains, although such relationship was not clear for other genes. The data suggest that the Japanese ARVA strains and the ones in Korea have genetically close relationship, although the origin is not clear at this point. Further information including the whole-genome sequences of the Korean strains and sequences of other Japanese chicken ARVA strains will be necessary for elucidation of their origin.

This study was undertaken to develop and validate a multiplex reverse transcription-polymerase chain reaction (mRT-PCR) for simultaneous detection of avian rotavirus, turkey astrovirus-2 (TAstV-2), and avian reovirus. Primers targeting the conserved regions of NSP4 gene of avian rotavirus, polymerase gene of TAstV-2, and S4 gene of avian reovirus were used. The position of bands at 630, 802, and 1120 base pairs on agarose gel confirmed the presence of rotavirus, TAstV-2, and reovirus, respectively. This mRT-PCR was found to be specific as no amplification was observed with avian influenza virus, Newcastle disease virus, turkey coronavirus, avian metapneumovirus, and intestinal contents of uninfected turkey poults. Intestinal contents of poults from flocks suspected of exhibiting “poult enteritis syndrome” were pooled and tested. Of the 120 pooled samples tested, 70% were positive for TAstV-2, 45% for avian rotavirus, and 18% for avian reovirus. These three viruses were detected alone or in different combinations. Of the samples tested, 20% were negative for these three viruses, 38% were positive for a single virus (TAstV or rotavirus or reovirus), and 42% were positive for two or three viruses. This single-tube mRT-PCR assay has the potential to serve as a rapid diagnostic method for the simultaneous detection of the three enteric viruses in turkeys.

Recent studies have revealed the presence of astroviruses and rotavirus in numerous poorly performing and healthy chicken and turkey flocks in the United States. The phylogenetic analysis of the sequence data produced during these studies has identified four groups of avian astroviruses circulating in the United States: turkey astrovirus types 1 and 2 (TAstV-1 and TAstV-2), avian nephritis virus (ANV), and a chicken-origin astrovirus (CAstV). As the molecular epidemiology of poultry enteric disease is poorly understood, the development of updated diagnostic assays is crucial to the continued surveillance and management of enteric disease in affected as well as healthy flocks. This report details the development of a multiplex reverse transcriptase–polymerase chain reaction (RT-PCR) assay specific for astroviruses and avian rotavirus in turkey-origin and chicken-origin samples. The assay consists of two multiplex tests, one for turkey-origin samples and one for chicken-origin samples. The turkey sample test differentially identifies TAstV-1, TAstV-2, ANV, and avian rotavirus. The test for chicken-origin samples differentially identifies CAstV, ANV, and avian rotavirus. Assay sensitivity varied by target sequence between approximately 10 copies for avian rotavirus alone and approximately 2 × 106 copies for TAstV-2 in the presence of a heterologous competitor RNA sequence. Each test was shown to be specific for the intended target by testing for cross-reaction with other common avian enteric viruses. The specificity was further shown by testing 109 chicken specimens and 32 turkey specimens from commercial flocks with the appropriate test and sequencing the RT-PCR amplicons to confirm amplification of the correct target.

A longitudinal survey to detect enteric viruses in intestinal contents collected from turkeys in eight commercial operations and one research facility was performed using molecular detection methods. Intestinal contents were collected from turkeys prior to placement, with each flock resampled at 2, 4, 6, 8, 10, and 12 wk of age. The samples were screened for astrovirus, rotavirus, reovirus, and turkey coronavirus (TCoV) by a reverse transcriptase and polymerase chain reaction (RT-PCR), and for groups 1 and 2 adenovirus by PCR. Rotavirus was the only virus detected prior to placement (7 of 16 samples examined). All of the commercial flocks were positive for rotavirus and astrovirus from 2 until 6 wk of age, and most were intermittently positive until 12 wk of age, when the birds were processed. Of the 96 samples collected from birds on the farms, 89.5% were positive for astrovirus, and 67.7% were positive for rotavirus. All flocks were negative for TCoV, reovirus, and group 1 adenovirus at all time points, and positive for group 2 adenovirus (hemorrhagic enteritis virus) at 6 wk of age. All the flocks monitored were considered healthy or normal by field personnel. Turkeys placed on research facilities that had been empty for months and thoroughly cleaned had higher body weights and lower feed conversion rates at 5 wk of age when compared to turkeys placed on commercial farms. Intestinal samples collected at 1, 2, and 3 wk of age from these turkeys were free of enteric viruses. This report demonstrates that astroviruses and rotaviruses may be present within a turkey flock through the life of the flock. Comparison of infected birds with one group of turkeys that were negative for enteric viruses by the methods used here suggests that astrovirus and/or rotavirus may affect production. The full impact on flock performance needs to be further determined.

Avian rotavirus A (ARtV-A) is a virus that affects young birds, causing acute diarrhea and economic losses in the poultry industry worldwide. The techniques used for the diagnosis of ARtV-A include electron microscopy, isolation in cell culture, and serology, as well as molecular techniques, such as the reverse transcription-polymerase chain reaction (RT-PCR). The objective of this work was to standardize a real-time RT-polymerase chain reaction (RT-qPCR) using SYBR Green chemistry for the rapid detection and quantification of ARtV-A from bird tissues and materials fixed on FTA cards on the basis of the nucleotide sequence of segment 6 (S6), which codes for the structural VP6 protein of ARtV-A. The results show the efficient amplification of the proposed target, with a limit of detection (LoD) of one copy gene (CG) per microliter of cDNA and a limit of quantification (LoQ) of 10 CGs per microliter. The efficiency of the primers was determined to be 95.66% using a standard curve, with an R2 value of 0.999 and a slope of −3.43. The specificity was determined using samples coinfected with ARtV-A, the chicken parvovirus, the chicken astrovirus, and the avian nephritis virus as positive controls and commercially available vaccines of the infectious bronchitis virus, infectious bursa disease virus, avian reovirus and healthy organs as negative controls. This technique, which lacks nonspecific PCR products and dimers, demonstrated greater sensitivity and specificity than conventional RT-PCR, and it reduced the analysis time by more than 50%.

The use of molecular methods for rotavirus characterisation provides increased sensitivity for typing and allows the identification of putative reassortant strains. Reagents and methods for genotyping the virus need constant modification because of the reassortant nature of the virus. This study was aimed at designing and evaluating new oligonucleotide degenerate primer pairs that provide increased sensitivity and specificity for detecting avian rotavirus. Gene-specific primer pairs were designed by analysing different rotavirus strains isolated during the last decade by downloading them from the GenBank. The alignments were generated using clustal analysis from the BioEdit program. Degenerate nucleotides were included due to the reassortant nature of rotavirus. The consensus sequences were aligned using the BioEdit program and then treated with the Fast PCR software to derive the primers. The derived primer sequences were submitted for a BLAST search to ensure alignment was exclusive to the desired target genes. The designed primers had specific bands and were efficient in detecting rotavirus in faecal samples than previously published primers. Thus, a successful surveillance of rotaviruses requires that primer pairs be updated regularly in order to detect the emergence of novel or “unusual types”, which have occurred by genetic drift causing nucleotide changes at the primer binding sites that result in typing failures. We recommend the use of the proposed primers in molecular surveillance studies for efficient detection of avian rotavirus.

Segmented double-stranded RNA (dsRNA) viruses were identified by polyacrylamide gel electrophoresis (PAGE) technique in fecal samples from broiler chicken. A total of 378 fecal samples from 1-7 weeks old chickens were analyzed. dsRNA with migration profile characteristic of avian rotavirus (AvRV), reovirus (ARV) or picobirnavirus (PBV) was identified in 32 (8.5%), 7 (1.8%) and 13 (3.4%) samples, respectively. AvRV and ARV occurred more frequently in chickens up to 1 month old and were related with enteritis signs. Considering only fecal samples of chickens with diarrhea, the AvRV was detected in 37.8% (14/37) and the ARV in 13.5% (5/37) of analyzed samples. AvRV was identified in only 1.5% (4/274) and ARV was not detected in normal feces collected from assymptomatic chickens (controls). PBV dsRNA was detected in broiler chickens from two to seven weeks old, more frequently in feces with pasty consistency. The AvRV showed great electrophoretic profile variability in the dsRNA segments and nine different electropherotypes were identified. Variation in genome pattern was not observed in either ARV or PBV. A técnica de eletroforese em gel de poliacrilamida foi utilizada com o objetivo de identificar vírus com genoma contituído por RNA de fita dupla (dsRNA) segmentado, em material fecal de frangos de corte. Foram analisadas 378 amostras de fezes de aves, com idade entre a primeira e sétima semanas de vida, provenientes de granjas avícolas localizadas no Estado do Paraná, Brasil. dsRNA com perfil de migração característico de rotavírus (AvRV), reovírus (ARV) ou picobirnavírus (PBV), foi identificado em 32 (8,5%), 7 (1,8%) e 13 (3,4%) amostras, respectivamente. AvRV e ARV ocorreram com maior freqüência em aves com até um mês de idade e estiveram diretamente relacionados a fezes diarréicas e pastosas, provenientes de aves com sinais clínicos de enterite. Considerando-se apenas as amostras de fezes colhidas em aves com diarréia, o AvRV foi detectado em 37,8% (14/37) e o ARV em 13,5% (5/37) da amostragem analisada. Em fezes com aspectos normais (controle) obtidas de aves clinicamente sadias, o AvRV foi identificado em apenas 1,5% (4/274) e o ARV não foi detectado. O ácido nucléico do PBV foi detectado com maior freqüência em fezes pastosas colhidas de aves com duas a sete semanas de vida. O AvRV apresentou grande variabilidade eletroforética dos segmentos de dsRNA, tendo sido identificados nove eletroferotipos distintos. Não foram observadas variações no perfil genômico nas amostras de ARV e também de PBV.

Nontargeted metagenomic surveillance of the poultry enteric virome reveals underrecognized threats to poultry health and productivity in intensive production systems. In South Asia, avian rotavirus A (AvRV-A) and avian orthoreovirus (ARV) are frequently detected in broilers by conventional diagnostics, whereas chicken megrivirus genotype C (ChMeV-C) is often identified through metagenomic surveillance. Often present in both clinical disease and coinfections, these viruses may impair gut function, immune responses, and growth performance, yet their genomic diversity and evolutionary dynamics in poultry remain poorly characterized. Here, we report complete genomes of AvRV-A, ARV, and ChMeV-C strains co-detected via nontargeted metagenomic next-generation sequencing (ntNGS) in a pooled cloacal sample comprising 150 commercial broiler chickens (19 and 33 days old) collected from three commercial farms in Kamrup Rural District, Assam, Northeast India. Despite routine vaccination, all three flocks experienced > 10% mortality, poor weight gain, and postmortem lesions including pale kidneys and hepatomegaly. Phylogenetic analyses revealed segmental clustering in ARV and AvRV-A consistent with reassortment-driven divergence, though not supported by detectable recombination, while ChMeV-C clustered within a distinct C1 sublineage, suggesting intercontinental lineage connectivity and highlighting the need to expand regional genomic baseline data. We also identified nonsynonymous single nucleotide polymorphisms in several key viral proteins, including RNA-dependent RNA polymerases (VP1 of AvRV-A, λB of ARV, and 3D of ChMeV-C), capsid proteins (VP2 and VP7 of AvRV-A, λA and σB of ARV, and VP0 and VP1 of ChMeV-C), and replication-associated nonstructural proteins. These findings expand the genomic baseline for poultry enteric viruses in South Asia, reveal novel polymorphic signatures, and underscore the value of ntNGS-based metagenomic surveillance in virus detection, diversity monitoring, and informing vaccine and biosecurity strategies.

Background Avian rotaviruses (RVs) cause gastrointestinal diseases of birds worldwide. However, prevalence, diversity, epidemiology and phylogeny of RVs remain largely under-investigated in Africa. Methods Fecal samples from 349 birds (158 symptomatic, 107 asymptomatic and 84 birds without recorded health status) were screened by reverse transcription PCR to detect RV groups A and D (RVA and RVD). Partial gene sequences of VP4, VP6, VP7 and NSP4 for RVA, and of VP6 and VP7 for RVD were obtained and analyzed to infer phylogenetic relationship. Fisher’s exact test and logistic regression were applied to identify factors potentially influencing virus shedding in chickens. Results A high prevalence of RVA (36.1%; 126/349) and RVD (31.8%; 111/349) shedding was revealed in birds. In chickens, RV shedding was age-dependent and highest RVD shedding rates were found in commercial farms. No negative health effect could be shown, and RVA and RVD shedding was significantly more likely in asymptomatic chickens: RVA/RVD were detected in 51.9/48.1% of the asymptomatic chickens, compared to 18.9/29.7% of the symptomatic chickens ( p  < 0.001/ p  = 0.01). First RVA sequences were obtained from mallard ducks ( Anas platyrhynchos ) and guinea fowls ( Numida meleagris ). Phylogenetic analyses illustrated the high genetic diversity of RVA and RVD in Nigerian birds and suggested cross-species transmission of RVA, especially at live bird markets. Indeed, RVA strains highly similar to a recently published fox rotavirus (RVA/Fox-tc/ITA/288356/2011/G18P[17]) and distantly related to other avian RVs were detected in different bird species, including pigeons, ducks, guinea fowls, quails and chickens. Conclusion This study provides new insights into epidemiology, diversity and classification of avian RVA and RVD in Nigeria. We show that cross-species transmission of host permissive RV strains occurs when different bird species are mixed.