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It is well-established that the genetic diversity, regional prevalence, and broad host range of astroviruses significantly impact the poultry industry. In July 2022, a small-scale commercial broiler farm in China reported cases of growth retardation and a 3% mortality rate. From chickens displaying proventriculitis and pancreatitis, three chicken astroviruses (CAstV) isolates were obtained and named SDAU2022-1-3. Complete genomic sequencing and analysis revealed the unique characteristics of these isolates from known CAstV strains in ORF1a, ORF1b, and ORF2 genes, characterized by an unusually high variability. Analysis of amino acid mutations in ORF1a, ORF1b, and ORF2 indicated that the accumulation of these mutations played a pivotal role in the emergence of the variant strain. Inoculation experiments demonstrated that affected chickens exhibited liver and kidney enlargement, localized proventricular hemorrhage, and a dark reddish-brown appearance in about two-thirds of the pancreas. Histopathological examination unveiled hepatic lymphocytic infiltration, renal tubular epithelial cell swelling, along with lymphocytic proventriculitis and pancreatitis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis indicated viremia and viral shedding at 3 days post-infection (dpi). The proventriculus displayed the highest viral loads, followed by the liver, kidney, duodenum, and pancreas. Liver parameters (AST and ALT) and kidney parameters (UA and UN) demonstrated mild damage consistent with earlier findings. While the possibility of new mutations in the ORF2 gene of CAstV causing proventriculitis and pancreatitis warrants further investigation, these findings deepen our comprehension of CAstV's pathogenicity in chickens. Additionally, they serve as valuable references for subsequent research endeavors. [ABSTRACT FROM AUTHOR]

Simple Summary: We developed the DAS–ELISA to investigate the infection and prevalence of GyH1 in chickens and wild birds in China. We found that natural GyH1 infections were widespread in chickens and wild birds. Importantly, young chickens are more susceptible to GyH1, and local chicken species in China are genetically resistant to GyH1. In particular, we found a significantly higher GyH1–positive rate in wild birds than in chickens, implying that there may be a risk of GyH1 transmission from wild birds to chickens. Gyrovirus homsa1 (GyH1) is an emerging pathogenic single–stranded circular DNA virus that leads to immunosuppression, aplastic anemia, and multisystem damage in chickens. However, the prevalence of GyH1 infection in chickens and wild birds remains unknown. Here, we developed a double–antibody sandwich enzyme–linked immunosorbent assay (DAS–ELISA) to investigate GyH1 infection in 8 chicken species and 25 wild bird species. A total of 2258 serum samples from chickens (n = 2192) in 15 provinces, and wild birds (n = 66) in Jinan Wildlife Hospital were collected from 2017 to 2021 in China. The GyH1–positive rates in chickens and wild birds were 9.3% (203/2192) and 22.7% (15/66), respectively. GyH1 was present in all flocks in 15 provinces. From 2017 to 2021, the positive rate ranged from 7.93% (18/227) to 10.67% (56/525), and the highest positive rate was present in 2019. Upon chicken age, the highest positive rate (25.5%) was present in young chickens (14–35 days old). Moreover, the GyH1–positive rate in broiler breeders (12.6%, 21/167) was significantly higher than that in layer chickens (8.9%, 14/157). This study shows that GyH1 has spread in chicken flocks and wild birds, and the higher GyH1–positive rate in wild birds indicates the risk of spillover from wild birds to chickens. Our study expanded the GyH1 epidemiological aspects and provided a theoretical basis for GyH1 prevention. [ABSTRACT FROM AUTHOR]

Background: Transmissible viral proventriculitis (TVP) causes significant economic loss to the poultry industry. However, the exact causative agents are obscure. Here we examine the virome of proventriculus from specified pathogen free (SPF) chickens that reproduced by infection of proventricular homogenate from broiler chicken with TVP using long read sequencing of the Pacific Biosciences RSII platform. The normal SPF chickens were used as control. Results: Our investigation reveals a virome of proventriculitis, including three Gyrovirus genera of the Aneloviridae: Gyrovirus homsa1 (GyH1) (also known as Gyrovirus 3, GyV3) (n = 2662), chicken anemia virus (CAV) (n = 482) and Gyrovirus galga1 (GyG1) (also known as avian Gyrovirus 2, AGV2) (n = 11); a plethora of novel CRESS viral genomes (n = 26) and a novel genomovirus. The 27 novel viruses were divided into three clusters. Phylogenetic analysis showed that the GyH1 strain was more closely related to the strains from chicken (MG366592) than mammalian (human and cat), the GyG1 strain was closely related to the strains from cat in China (MK089245) and from chicken in Brazil (HM590588), and the CAV strain was more closely related to the strains from Germany (AJ297684) and United Kingdom (U66304) than that previously found in China. Conclusion: In this study, we revealed that Gyrovirus virome showed high abundance in chickens with TVP, suggesting their potential role in TVP, especially GyH1. This study is expected to contribute to the knowledge of the etiology of TVP. [ABSTRACT FROM AUTHOR]

Background: Gyrovirus homsa1 (GyH1) (also known as Gyrovirus 3, GyV3) is a non-enveloped, small, single-stranded DNA virus, which was first identified in children with acute diarrhea, and was subsequently detected in marketed chickens, broilers with transmissible viral proventriculitis (TVP), and mammals. GyH1 is a pathogenic virus in chickens, causing aplastic anemia, immunosuppression, and multisystem damage. However, the seroepidemiology of GyH1 infection in chickens remains unclear. Here, we investigated the seroprevalence of GyH1 in chickens by ELISA to reveal the endemic status of GyH1 in China. Results: An indirect ELISA with high sensitivity and specificity was developed for investigation of seroepidemiology of GyH1 in chickens in China. The seropositive rate of GyH1 ranged from 0.6% to 7.7% in thirteen provinces, and ranged from 4.1% to 8.1% in eight species chickens. The seropositive rate of GyH1 in broiler breeders was significantly higher than that of in layers. There was a negative correlation between seropositive rate and age of chickens. The highest and lowest seropositive rate were present in chickens at 30–60 days and over 180 days, respectively. Conclusions: The seroepidemiological investigation results demonstrated that natural GyH1 infection is widespread in chickens in China. Different species showed different susceptibility for GyH1. Aged chickens showed obvious age-resistance to GyH1. GyH1 has shown a high risk to the poultry industry and should be highly concerned. [ABSTRACT FROM AUTHOR]

This study reports outbreak of a new disease caused by Staphylococcus pseudintermedius (S. pseudintermedius) in raccoon dogs. The disease occurred in a breeding farm of raccoon dogs in Guan County of Shandong Province in China in August of 2019. 47% (425/896) of the raccoon dogs showed some abnormal symptoms; 17.6% (75/425) of which had severe skin and soft tissue infections (SSTIs), dyspnoea and severe pathological lesions in lungs, livers, etc; and 4.2% (18/425) of which died within 4 weeks. The pathogen of the disease was identified as S. pseudintermedius by mass spectrometer detection, animal pathogenicity tests, microscopic examination and biochemical reaction tests. Its nucleotide homology of 16S rRNA gene was 100% with that of other published strains, and its genotype was between the American and Brazilian strains from other animals. The isolated S. pseudintermedius strain from the diseased raccoon dogs could cause ulceration and suppuration in the skins and severe pathological lesions not only in raccoon dogs, but also in mice; and it is confirmed as a methicillin‐resistant S. pseudintermedius (MRSP) strain by the amplification of mecA gene; and 12 sensitive drugs were screened by drug sensitivity tests. Full attention should be paid to the great economic loss and the potential zoonotic risk caused by the S. pseudintermedius in raccoon dogs, and this study can provide a reference for the clinical diagnosis and treatment of this new disease. [ABSTRACT FROM AUTHOR]

Circoviruses are found in many species, including mammals, birds, lower vertebrates and invertebrates. To date, there are no reports of circovirus‐induced diseases in chickens. In this study, we identified a new strain of chicken circovirus (CCV) by PacBio third‐generation sequencing samples from chickens with acute gastroenteritis in a Shandong commercial broiler farm in China. The complete genome of CCV was verified by inverse PCR. Genomic analysis revealed that CCV codes two inverse open reading frames (ORFs), and a potential stem‐loop structure was present at the 5′ end with a structure typical of a circular virus. Phylogenetic tree analysis showed that CCV formed an independent branch between mammalian and avian circovirus, and homology analysis indicated that the homology of CCV with 21 other known circoviruses was less than 40%. Thus, this CCV strain represents a new species in the genus Circovirus. The infection rate of CCV in 12 chickens with diarrhoea was 100%, but no CCV was found in healthy chickens, thereby indicating that the novel CCV strain is highly associated with acute infectious gastroenteritis in chickens. The emergence of a novel CCV in commercial broiler chickens is highly concerning for the broiler industry. [ABSTRACT FROM AUTHOR]

GX0101 is the first field Marek's disease virus (MDV) recombinant with an REV LTR insert isolated in China. We speculated that there was a selective advantage of GX0101 becoming the more prevalent field strain from a very low percentage of recombinant virus. In the study, dual fluorescence quantitative real-time PCR (DF-qPCR) that detects GX0101 and GX0101Δ LTR simultaneously was established based on the genomic difference of GX0101 and its LTR deletion strain GX0101Δ LTR. MDV natural transmission was simulated in specific-pathogen-free (SPF) chicks, and continuous tracking of GX0101 and GX0101Δ LTR in chicks was carried out. The results showed that GX0101 possessed high horizontal transmission capacity, which could infect SPF chicks by contact in a short time and became the predominant strain following contact infections in chicken flocks. GX0101 still had a more significant advantage of horizontal transmission than GX0101Δ LTR after continuous passage even if the initially infectious dose was significantly lower. There were 72 differentially expressed MDV genes between GX0101 and GX0101Δ LTR , with the genes and gene products mainly involved in virus replication, tegument protein, glycoprotein, nucleocapsid protein, immune evasion, tumor development and/or pathogenesis, and hypothetical protein. Sixteen genes related to virus replication and transmission were significantly up-regulated. This is the first study to illuminate that increased horizontal transmission of recombinant MDV due to REV LTR was the competitive advantage of the virus being a prevalent strain and define the differential transcription profile of viral genes between GX0101 and GX0101Δ LTR. This will be helpful for in-depth study on the molecular mechanism of increased horizontal transmission of MDV by REV LTR. [ABSTRACT FROM AUTHOR]

Avian leukosis virus subgroup J (ALV‐J) was isolated in meat‐type breeder chickens for the first time in 1988 in the United Kingdom. Due to the application of an eradication program, there were fewer reports related to myelocytomatosis or ALV‐J in China after 2013. However, there was another breakout almost simultaneously in six provinces of China in February 2018. On‐site, 15‐ to 20‐week‐old broiler breeder chickens showed depression, paralysis and weight loss. Mortality for certain flocks reached 15%. Sick chickens showed numerous yellow–white neoplasms growing in the sternum, rib and lumbar vertebra and had hepatic and renal metastasis. Histopathological observation showed all neoplasms were myelocytomas, and there were massive myelocyte‐like tumour cells in the liver, kidney and bone marrow. To explore the aetiology of this re‐outbreak of myelocytomatosis in China, we collected tumour‐bearing chickens and isolated six strains of ALV‐J (GM0209‐1 to ‐6). Phylogenetic analysis of gp85 and gp37 showed GM0209 strains were clearly distinct from the prototype strain of ADOL‐7501, HPRS‐103 and NX0101, and there was a mutation, R176G, in the conserved region between hr1 and hr2 regions of gp85, which was not found in other 44 ALV‐J strains. The 3′UTR nucleotide sequences of GM0209 isolates showed there was a signature deletion of 11 nt that was also present in 3′UTR sequences of SCDY1 and NHH, two isolates that have a reported association with haemangioma, indicating this deletion could not determine the tumour type induced by ALV‐J. Although the eradication program of ALV‐J has been successfully applied in China, the outbreak of ALV‐J still occurred, and the virus strain spread quickly. Thus, the biocharacteristics and pathogenesis of mutational ALV‐J should be further studied. [ABSTRACT FROM AUTHOR]

The past few years have witnessed a rapid increase in cases of viral arthritis caused by avian reovirus (ARV) in chicken farms in China, attributed to the emergence of variant strains that render traditional vaccines ineffective, leading to substantial economic losses. In this study, we successfully isolated a novel ARV strain, designated as 2023ARV-GS-SDAU-1, from chickens in a broiler flock vaccinated with an ARV vaccine in Gansu province. We performed whole-genome sequencing and assessed its pathogenicity through 2 infection routes: oral administration and intraperitoneal injection. Our analysis revealed significant variations in the σA gene, associated with the inhibition of interferon secretion, compared to known ARV strains. The highest nucleotide identity observed was below 80%. Additionally, the σC gene exhibited notable variations compared to its homologous strains within the same group. Multiple alignment of the amino acid sequences classified the 2023ARV-GS-SDAU-1 strain under genotype I. Furthermore, our pathogenicity experiments indicated that the isolated strain exhibited more severe pathogenicity when administered via intraperitoneal injection in SPF chickens. In summary, our data suggest that the 2023ARV-GS-SDAU-1 strain represents a novel variant circulating in broiler flocks in China. These findings enrich currently available genetic information on ARV strains and provide a new complete genome sequence. [ABSTRACT FROM AUTHOR]

Tibetan chicken is found in China Tibet (average altitude; ˃4500 m). However, little is known about avian leukosis virus subgroup J (ALV-J) found in Tibetan chickens. ALV-J is a typical alpharetrovirus that causes immunosuppression and myelocytomatosis and thus seriously affects the development of the poultry industry. In this study, Tibet-origin mutant ALV-J was isolated from Tibetan chickens and named RKZ-1-RKZ-5. A Myelocytomatosis outbreak occurred in a commercial Tibetan chicken farm in Shigatse of Rikaze, Tibet, China, in March 2022. About 20% of Tibetan chickens in the farm showed severe immunosuppression, and mortality increased to 5.6%. Histopathological examination showed typical myelocytomas in various tissues. Virus isolation and phylogenetic analysis demonstrated that ALV-J caused the disease. Gene-wide phylogenetic analysis showed the RKZ isolates were the original strains of the previously reported Tibetan isolates (TBC-J4 and TBC-J6) (identity; 94.5% to 94.9%). Furthermore, significant nucleotide mutations and deletions occurred in the hr1 and hr2 hypervariable regions of gp85 gene, 3'UTR, Y Box, and TATA Box of 3'LTR. Pathogenicity experiments demonstrated that the viral load, viremia, and viral shedding level were significantly higher in RKZ-1-infected chickens than in NX0101-infected chickens. Notably, RKZ-1 caused more severe cardiopulmonary damage in SPF chickens. These findings prove the origin of Tibet ALV-J and provide insights into the molecular characteristics and pathogenic ability of ALV-J in the plateau area. Therefore, this study may provide a basis for ALV-J prevention and eradication in Tibet. • Mutant ALV-J is prevalent in Tibetan chickens in Tibet of China. • RKZ isolates occurs nucleotides mutations in SU protein. • RKZ-1 caused serious cardiopulmonary damage. [ABSTRACT FROM AUTHOR]

• GyVs were widely distributed in China, particularly, co-infection within the three species GyVs in same individual, which had never been reported before. • CAV and GyG1 had similar recombination regions and were associated with viral replication and transcription. • The high substitution rate and recombination were the main factors for the high diversity of GyVs. Gyrovirus (GyV) is a widespread ssDNA virus with a high population diversity, and several of its species, including the chicken anemia virus (CAV), gyrovirus galga 1 (GyG1), and gyrovirus homsa 1 (GyH1), have been shown to be pathogenic to poultry. The evolution of these viruses, however, is still unclear. Our study analyzed epidemiology and molecular evolution of three species of GyVs (CAV, GyG1, and GyH1) from 2018 to 2019 in China. The survey results indicated that GyV was widespread in China. It is vital to consider the coinfections among the three species of GyV. The phylogenetic analysis showed that CAV was divided into three clades and GyG1 and GyH1 were divided into two clades. Based on the recombination analysis, CAV and GyG1 had similar recombination regions associated with viral replication and transcription. Furthermore, the substitution rates for CAV and GyG1 were approximately 6.09 × 10−4 and 2.784 × 10−4 nucleotides per site per year, respectively. The high substitution rate and recombination were the main factors for the high diversity of GyVs. Unfortunately, GyH1 strains have not been discovered in enough numbers to allow evolutionary analysis. The GyVs had several positively selected sites, possibly related to their potential to escape the host immune response. In summary, our study provides insights into the time of origin, evolution rate, and recombination of GyV for assessing their evolutionary process and genetic diversity. [ABSTRACT FROM AUTHOR]

Abstract: The present study conducts a serological survey on the presence of canine dirofilariosis in domestic dogs using an enzyme-linked immunosorbent assay (ELISA) kit. A total of 310 household dogs (166 females and 144 males) in Chongqing, Kunming, Nanchang, Fuzhou, Guangzhou, Shenzhen, and Nanning in Southern China were examined. Of the 310 dogs, 42 (13.5%) were seropositive for dirofilariosis. No statistically significant difference was observed in terms of sex in the seroprevalence of dirofilariosis using the ELISA kit. The positive rates for dirofilariosis were 6.6% in the 0–1-year-old group, 13.8% in the 1–4-year-old group, and 21.6% in the less than 4-year-old group. The statistical analysis revealed that significant differences were observed in the 1–4-year-old group (P =0.037, OR=0.441, 95% CI=0.170–1.144) and less than 4-year-old group (P <0.001, OR=0.256, 95% CI=0.095–0.693). In the regional comparison, the shoreline city Shenzhen (18.8%) had a significantly higher prevalence than urban and mountain areas (P <0.05, OR=0.310, 95% CI=0.066–1.445). In conclusion, Dirofilaria immitis infection in domestic dogs was present in Chongqing, Kunming, Nanchang, Fuzhou, Guangzhou, Shenzhen, and Nanning. Therefore, heartworm treatment and/or chemoprophylaxis for the captured domestic dogs are necessary in these areas. To the best of our knowledge, the present study is the first using serological methods to examine D. immitis infection in domestic dogs in Mainland China in the recent years. [Copyright &y& Elsevier]

Macrococcus caseolyticus is generally considered to be a non-pathogenic bacterium that does not cause human or animal diseases. However, recently, a strain of M. caseolyticus (SDLY strain) that causes high mortality rates was isolated from commercial broiler chickens in China. The main pathological changes caused by SDLY included caseous exudation in cranial cavities, inflammatory infiltration, haemorrhages and multifocal necrosis in various organs. The whole genome of the SDLY strain was sequenced and was compared with that of the non-pathogenic JCSC5402 strain of M. caseolyticus. The results showed that the SDLY strain harboured a large quantity of mutations, antibiotic resistance genes and numerous insertions and deletions of virulence genes. In particular, among the inserted genes, there is a cluster of eight connected genes associated with the synthesis of capsular polysaccharide. This cluster encodes a transferase and capsular polysaccharide synthase, promotes the formation of capsules and causes changes in pathogenicity. Electron microscopy revealed a distinct capsule surrounding the SDLY strain. The pathogenicity test showed that the SDLY strain could cause significant clinical symptoms and pathological changes in both SPF chickens and mice. In addition, these clinical symptoms and pathological changes were the same as those observed in field cases. Furthermore, the anti-microbial susceptibility test demonstrated that the SDLY strain exhibits multiple-antibiotic resistance. The emergence of pathogenic M. caseolyticus indicates that more attention should be paid to the effects of this micro-organism on both poultry and public health., (© 2018 Blackwell Verlag GmbH.)

Background: Emaciation, depression and lethargy were observed in two flocks of Chinese local breed and one flock of commercial layer chicken infected naturally from 2010 to 2011. The aims of this study were to diagnose., Methods and Results: Gross observation showed that severe enlargement of liver, spleen and kidney, and hemorrhage of thymus, muscle and glandular stomach in all submitted birds. The liver and lung of one flock had diffuse, multifocal white raised foci on the surface as well as on the cut-surface. Numerous erythrocytoblasts with bigger volume, basophilic cytoplasm and round nucleus were observed in blood and bone marrow smears. The same erythrocytoblasts were also found crowded in blood vessels and mesenchym of tissues by histological examination, and some had mitotic figures. PCR results showed that three flocks were positive for ALV-J with specific fragment of 924 bp, negative for AEV, ALV-A, ALV-B, Marek's disease virus (MDV) and Reticuloendotheliosis virus (REV). The results of immunohistochemistry showed that cytoplasm of histiocytes and erythrocytoblasts in lung and spleen sections was positive for ALV-J antigen., Conclusion: These data demonstrated that erythroblastosis was all induced by ALV-J in the three different flocks. This is the first document report of erythroblastosis induced by ALV-J in China flocks.

Seroprevalence of Toxoplasma gondii infection was determined in sera of 632 dogs (551 pets, 81 strays) from Shandong, Henan, and Heilongjiang Provinces, and in the Xinjiang Uygur Autonomous Region, People's Republic of China (PRC), using the indirect hemagglutination assay (cutoff titer 1:64 or higher); 11.1% were seropositive. The seroprevalence in stray dogs and in ≥3-yr-old dogs was significantly higher (P < 0.05) than that in household dogs and in <3-yr-old dogs. There were no significant differences in terms of gender, breed, or locality (P ≥ 0.05). The results indicate that T. gondii infections are common in dogs in PRC.

Babesiosis (piroplasmosis) is a zoonotic disease caused by an intraerythrocytic protozoan transmitted by Ixodes ticks. The aim of this study was to detect Babesia spp. infection using molecular methods in 377 blood samples from anemic patients. Sequence analysis showed that the 18S rRNA gene was 439 bases long by polymerase chain reaction (PCR) amplification and that the PCR products from the samples had an identical sequence (named Taian China, HM355854). BLAST search showed that the sequence was identical to the 18S rRNA sequences of Babesia divergens. The 18S rRNA sequence for Toxoplasma gondii was included as the outlier for phylogenetic analysis by using the program MEGA4.0 software. The results showed that the 18S rRNA gene sequences obtained from the present study was most closely related to B. divergens Switzerland (DQ312439) with 98.4% similarity (differing only by seven bases). The phylogenetic analysis also revealed that this sequence closely resembled B. divergens strains from other countries and belonged to the same clade. This is the first report of a human being infected by B. divergens in China.

In the 3 years leading up to November 2009, 6 different types of naturally occurring neoplasms associated with avian leukosis virus subgroup J (ALV-J) were diagnosed by histopathology, polymerase chain reaction (PCR) and immunohistochemistry (IHC) in 140 layer hens out of approximately 100,000. The most prevalent tumor type was hemangioma (50%) in commercial layer flocks; the second most prevalent neoplasm type was myelocytoma (38.6%); a small number of ALV-J positive lymphomas (4.3%) that were not associated with Marek's disease (MD) or lymphoid leukosis (LL) was observed. Histiocytic sarcomas (2.1%) were found mainly in the spleen, liver and kidney. Fibrosarcomas (2.8%) presented as metastatic thigh, liver, lung and kidney neoplasms. Three cases of intestinal adenocarcinoma (2.1%) were found associated with ALV-J. Chickens with multiple tumors were a common phenomenon. Usually, hemangiomas plus myelocytomas (8.6%), myelocytomas plus histiocytic sarcomas (2.1%), hemangioma plus myelocytoma and lymphoma (3.6%) were found in various viscera organs. The present report describes the occurrence of multiple neoplasms associated with ALV-J in field layer hens.

Two commercial flocks of Chinese partridge experienced increased mortality associated with a wasting disease at 120-day old in June 2006. Postmortem examination of dead chickens consistently showed visceral tissues mainly proventriculus, liver and spleen were diffuse enlargement. Microscopic examination revealed masses of immature lymphocytes with frequent mitotic figures were seen in various tissues including proventriculus, liver, spleen, kidney, heart, lung, thymus and intestine. Reticuloendotheliosis virus (REV) was isolated from each of four blood samples. Viral antigens were observed in cultured CEF (SPF embryos came from the Ji-nan poultry institute) inoculated blood samples via on indirect immunofluorescent assay. Three hundred bp fragments of LTR of REV obtained from liver samples of six chickens by PCR. This disease has not previously been reported in Chinese partridge. Chinese partridge may represent a potential reservoir of infection for other Chinese local chickens.