Goose Circovirus Research Articles

Genetic heterogeneity of duck circovirus first detected in geese from China

Duck circovirus (DuCV) can infect domestic and wild ducks, retarding growth and suppressing immunity, thereby increasing the possibility of secondary infection by other pathogens. In this study, for the first time, 2 DuCV strains (G221116 and G210917) were identified in geese from China. To study the genetic characteristics of the 2 goose-originated DuCVs, multiple sequence alignment and phylogenetic analyses were perforemed according to genome sequences of 2 DuCV strains g and reference waterfowl circoviruses retrieved from the GenBank database. Pairwise analysis showed that the genome sequence identities between the 2 DuCVs with reference DuCV-1 and DuCV-2 strains were 80.95% to 98.24%, and 58.04% to 59.55% with Goose circovirus (GoCV). Phylogenetic analysis showed that the 2 DuCVs belonged to DuCV-1 and DuCV-2 genotypes. These results broaden our understanding of the genetic heterogeneity and evolution of DuCV and suggest trans-host transmission of DuCV between ducks and geese.

Codon usage bias of goose circovirus and its adaptation to host

Goose circovirus (GoCV), a potential immunosuppressive virus possessing a circular single-stranded DNA genome, is widely distributed in both domesticated and wild geese. This virus infection causes significant economic losses in the waterfowl industry. The codon usage patterns of viruses reflect the evolutionary history and genetic architecture, allowing them to adapt quickly to changes in the external environment, particularly to their hosts. In this study, we retrieved the coding sequences (Rep and Cap) and the genome of GoCV from GenBank, conducting comprehensive research to explore the codon usage patterns in 144 GoCV strains. The overall codon usage of the GoCV strains was relatively similar and exhibited a slight bias. The effective number of codons (ENC) indicated a low overall extent of codon usage bias (CUB) in GoCV. Combined with the base composition and relative synonymous codon usage (RSCU) analysis, the results revealed a bias toward A- and G-ending codons in the overall codon usage. Analysis of the ENC-GC3s plot and neutrality plot suggested that natural selection plays an important role in shaping the codon usage pattern of GoCV, with mutation pressure having a minor influence. Furthermore, the correlations between ENC and relative indices, as well as correspondence analysis (COA), showed that hydrophobicity and geographical distribution also contribute to codon usage variation in GoCV, suggesting the possible involvement of natural selection. In conclusion, GoCV exhibits comparatively slight CUB, with natural selection being the major factor shaping the codon usage pattern of GoCV. Our research contributes to a deeper understanding of GoCV evolution and its host adaptation, providing valuable insights for future basic studies and vaccine design related to GoCV.

TaqMan-probe-based multiplex real-time RT-qPCR for simultaneous detection of GoAstV, GPV, and GoCV

Goose astrovirus (GoAstV), goose parvovirus (GPV), and goose circovirus (GoCV) infections have similar symptoms, such as severe diarrhea, and cause serious economic losses to the goose industry globally. Therefore, it is necessary to develop a rapid and accurate method for the differential diagnosis of the 3 viruses. In this study, a TaqMan probe-based multiplex reverse transcription-qualitative polymerase chain reaction (RT-qPCR) method was established and optimized for simultaneous detection of the three viruses. Three pairs of specific primers and probes were designed considering the conserved sequences of ORF2, VP3, and Rep of GoAstV, GPV, and GoCV, respectively. Singleplex real-time RT-qPCR detected a minimum of 10 copies of these genes, while multiplex real-time RT-qPCR detected a minimum of 100 copies. The correlation coefficients exceeded 0.99, and the amplification efficiency was 80 to 100%. The assay had high sensitivity, specificity, and repeatability. In 85 tissue samples, GoAstV and GPV were the main pathogens and demonstrated co-infection. This assay provides a rapid, efficient, specific, and sensitive tool for the detection of GoAstV, GPV, and GoCV. This can facilitate disease management and epidemiological surveillance.

The Prevalence, Coinfection, and Evolutionary and Molecular Characteristics of Prevalent Goose Circovirus in Guangdong, China.

To understand the prevalence, coinfection with other viruses, underlying genetic evolution, recombination, and molecular biological characteristics of goose circovirus (GoCV) in Guangdong, China, from December 2019 to August 2020, 310 tissue samples of geese showing stunted growth and feather disorder syndrome were collected from this region and analyzed. GoCV, Tembusu virus, waterfowl paramyxovirus, avian influenza virus, fowl adenovirus type 4, and duck plague virus were detected with PCR or real-time PCR. Thirty-one complete GoCV viral genomes were obtained from 164 PCR-verified GoCV nucleotide-positive samples and subjected to phylogenetic analysis, gene recombination analysis, and genome secondary structure prediction. The results showed that more than half of the samples were GoCV positive, and 31.1% of the GoCV-positive samples were from coinfections with at least one of the other viruses. The phylogenetic analysis showed that the GoCVs could be divided into three genome types. The genes of most main epidemic strains now circulating in Guangdong belonged to the Ia subtype, and some strains gradually formed a new Ib subtype. The secondary structure of the viral genome was similar to that of other known circoviruses. Furthermore, B cell linear epitope prediction and protein structure homology modeling of the viral capsid protein were performed based on the viral amino acid sequences. The results showed that the spatial structure of the capsid protein of the 31 sequenced strains was similar to that of duck circovirus and consisted of two β-sandwich conformations. A total of five B cell linear epitopes were predicted, and four of them were mapped on the predicted model of the capsid protein of GoCVs. This report provides a reference for the epidemiology of GoCV in Guangdong, understanding the elemental composition of the virus genes and proteins, selecting representative vaccine strains, constructing targeted immune preparations for GoCV, and strengthening prevention and control of the disease.

Emergence of a novel pegivirus species in southwest China showing a high rate of coinfection with parvovirus and circovirus in geese

Previously, we isolated a novel strain of goose pegivirus (GPgV) that infects geese and shows high levels of lymphotropism. This novel pegivirus strain is phylogenetically distinct from previously known Pegivirus species, Pegivirus A-K, and qualifies as a candidate new Pegivirus species, GPgV. GPgV is tentatively named Pegivirus M. Here, to better understand the epidemic of GPgV infection and the coinfection of this virus with other viruses in Southwest China, 25 geese in poor health from Sichuan Province and 24 geese in poor health from the municipality of Chongqing were collected. The geese were tested for 9 types of goose viruses (goose hemorrhagic polyomavirus, GPgV, astrovirus, parvovirus, circovirus, reovirus, coronavirus, paramyxovirus, and avian influenza virus) by RT-PCR or nested RT-PCR. GPgV RNA was detected in 2 out of 25 monoinfections and 8 out of 25 coinfections with other viruses on Sichuan farms and 2 out of 24 monoinfections and 10 out of 24 coinfections on Chongqing farms. Overall, 22 of the 49 (44.9%) geese were positive for GPgV, which indicated a high infection rate. To the best of our knowledge, this is the first report of GPgV coinfection with other epidemic viruses. This study enhances our understanding of the emergence and epidemiology of Pegivirus.

Correlation between goose circovirus and goose parvovirus with gosling feather loss disease and goose broke feather disease in southern Taiwan.

BackgroundGoslings in several Taiwanese farms experienced gosling feather loss disease (GFL) at 21–35 days and goose broke feather disease (GBF) at 42–60 days. The prevalence ranges from a few birds to 500 cases per field. It is estimated that about 12,000 geese have been infected, the morbidity is 70–80% and the mortality is 20–30%.ObjectivesThis study aims to investigate the pathogens that cause GFL and GBF. Focus on the study of the correlation between goose circovirus (GoCV) and goose parvovirus (GPV) with the goose feather loss in southern Taiwan. Furthermore, a phylogenetic tree was established to align the differences between southern and northern Taiwan and compare with virus strains from China and Europe.MethodsSamples were collected from animal hospitals. Molecular and microscopy diagnostics were used to examine 92 geese. Specific quantitative polymerase chain reaction (Q-PCR) assays are performed to evaluate GPV and GoCV viral loads and simultaneously evaluated the feather loss conditions in geese with the scoring method.ResultsHigh prevalence of GoCV and GPV infection in geese showing signs of GFL and GBF. Inclusion body was detected in the feather follicles and Lieberkühn crypt epithelial cells. The Q-PCR showed the high correlation between feather loss and viruses during 3rd–5th week. However, the infection was not detected using the same test in 60 healthy geese.ConclusionsThus, GFL and GBF appear to be significantly closely related to GoCV and GPV. The geese feathers showed increasing recovery after being quarantined and disinfected.

Coinfection of parvovirus and astrovirus in gout-affected goslings.

Outbreaks of gosling gout have occurred in China since 2017 and caused a considerable economic impact on the poultry industry. While gosling astrovirus (GoAstV) is believed to be the main causal pathogen of gout, the full-blown disease of gout cannot be well reproduced by infecting the goslings with GoAstV, suggesting the possibility of other infectious agents being involved with the development of gosling gout. To assess other possible infectious agents, we collected tissues from gout-affected goslings in 12 goose farms in China, followed by PCR detection of GoAstV, goose reovirus (GRV), goose parvovirus (GPV), fowl adenovirus (FAdV), goose circovirus (GcoV), Tembusu virus (TMUV) and goose haemorrhagic polyomavirus (GHPV). Our data showed that all gout-affected goslings carried both of GoAstV and GPV determined by PCRs, and this was further confirmed by fluorescence multiplex immunohistochemical staining, and phylogenetic analysis of ORF2 gene of GoAstV and VP3 gene of GPV. In addition to the haemorrhage in the kidney, liver, spleen and lung of the gout-affected goslings, histological examinations showed also extensive infiltration of heterophil myelocytes in the kidney, liver, spleen, bursa of Fabricius, thymus, lungs and pancreas. Our findings strongly suggest that coinfection of GoAstV and GPV increases the severity of gout. While this is the first study to report GPV in gout-affected goslings, further studies including infection model are warranted to investigate the role of GPV and its coinfection with GoAstV in the development of gosling gout.

Occurrence and genetic diversity of CRESS DNA viruses in wild birds: a Hungarian study

Circoviruses, cycloviruses and other circular, replication-associated protein-encoding single stranded (CRESS) DNA viruses have been detected in a variety of animal taxa. In this study, cloacal swab samples (n = 90) were examined for CRESS DNA viruses from 31 wild bird species living at various aquatic sites in Hungary to identify possible reservoirs of viruses pathogenic to domestic poultry. A total of 30 (33.3%) specimens tested positive with pan-CRESS DNA virus specific PCR. Goose circovirus (GoCV), Duck associated cyclovirus 1 (DuACyV-1) and Garrulus glandarius associated circular virus 1 (GgaCV-1) were detected in nine, three and two different bird species, respectively. Selected specimens were subjected to whole genome sequencing. The obtained sequence data revealed conserved gene structure within the identified virus species and detected homologous (within GoCV) and possible heterologous recombination (within DuACyV-1) events. Results presented here provide new information on the genomic diversity and evolution of selected CRESS DNA viruses.

A TaqMan-based quantitative real-time PCR assay for identification of the goose circovirus

Goose circovirus (GoCV) is a potential immunosuppressive virus that poses a great hazard to the goose industry and has been shown to be widely distributed throughout China. We have established a fast, sensitive and highly specific TaqMan real-time quantitative PCR detection method for this virus. Specific primers and probes were designed against the conserved regions of the genomic GoCV Rep gene. The results showed that the assay was highly specific and sensitive for GoCV and did not cross-react with other non-targeted waterfowl viruses. The established method will be helpful for epidemiological detection and may be effective in the prevention and control of the disease.

Elaboration of Triplex PCR for Detection of Selected Viral Infections in Waterfowl.

IntroductionViral infections are the greatest threat to waterfowl and cause significant economic losses. Diagnosis and differentiation of three goose viruses is difficult in the field and often requires laboratory confirmation. Therefore, the aim of the study was to develop a triplex PCR and optimise its parameters for simultaneous detection of DNA of goose parvovirus (GPV), goose polyomavirus (GHPV), and goose circovirus (GoCV).Material and MethodsThe DNA of viruses isolated from field cases from the National Veterinary Research Institute’s own collection was used for the study. The primer attachment temperature, the number of reaction cycles, and the Taq DNA polymerase and Mg2+ concentrations were optimised. The sensitivity and specificity of this triplex PCR was also determined.ResultsBased on the obtained results, triplex PCR parameters were optimised for simultaneous detection of DNA of GPV, GHPV, and GoCV in one sample. The following PCR products of the expected size were obtained: GPV DNA of 806 bp, GoCV DNA of 571 bp, and GHPV DNA of 180 bp.ConclusionThe developed triplex PCR method proved to be useful for simultaneous detection of infections with three waterfowl viruses and will be used in relevant laboratory diagnostics.

Epidemiological investigation of H9 avian influenza virus, Newcastle disease virus, Tembusu virus, goose parvovirus and goose circovirus infection of geese in China.

To deepen the knowledge about epidemic prevalence in the goose breeding field, a triplex PCR assay was established, and 478 samples were collected from scaled goose farms in 11 provinces in China. The results of this epidemiological investigation showed that incidence rates of H9 avian influenza and goose circovirus were the highest among five infectious diseases that were evaluated. In addition, the triplex PCR assay established remarkable sensitivity, rapidity and versatility compared to other diagnostic methods. Dual infection comprised a large proportion of the co-infections in the field, of which the combinations of H9/Tembusu, H9/goose circovirus and goose circovirus/Tembusu co-infected cases were more common. Epidemics were more severe in winter and spring. Additionally, significant differences in the prevalence of these infectious diseases were observed in association with different age groups. In addition, phylogenetic analysis, determined by the neighbour-joining method, was carried out to investigate the evolution of these viruses during the study period. For the most part, virus strains isolated during the study were consistent with most goose-origin strains isolated from the Chinese mainland over the past few years. However, mutations were observed between isolated H9 avian influenza virus strains and sequences available from GenBank, which should draw much attention.

Goose Parvovirus and Circovirus Coinfections in Ornamental Ducks

Clinical observations and diagnostic procedures carried out to elucidate the cause of high mortality in 2-8-wk-old ornamental ducks (mandarin, wood, falcated, and silver teal ducks) are described. At necropsy, ducklings showed general pallor of skeletal and heart muscles, subcutaneous gelatinous transudates, pericarditis, ascites, and severe edema and hyperemia of lungs. Histopathologic examination revealed that the most important changes were located in the crop, bursa of Fabricius, and lungs with presence of amorphic basic intracytoplasmic inclusions. No bacteria or fungi could be detected from affected organs and ascitic fluid. Viral diagnosis included molecular detection for the presence of goose parvovirus (GPV), circovirus, avian influenza, herpesviruses, paramyxovirus, reovirus, and polyomavirus. Both GPV and circovirus could be detected by real-time PCR and nested broad-spectrum PCR, respectively. Phylogenetically, full-length nucleotide sequence of GPV showed a close similarity ranging from 95.6% to 97.9% with European and Asian pathogenic GPV. On the other hand, the detected circovirus showed nucleotide identity of 90% to 98% with goose circoviruses (GoCVs). This is the first report of GoCVs and GPV in ornamental ducks. The concurrence of GPV and GoCV infections is thought to contribute to the high mortality.

Genome Sequence of a Diverse Goose Circovirus Recovered from Greylag Goose.

A diverse goose circovirus (GoCV) genome was recovered from a wild hunted greylag goose (Anser anser) in Poland. The genome shares 83% pairwise identity with other GoCV genomes recovered from various geese from China, Germany, and Taiwan.

Viral infections in goose flocks in Poland

The aim of this study was to determine the infectious agents isolated from infection - suspected geese sent for the diagnostic examination to National Veterinary Research Institute. The birds were sent from goose flocks localized in different parts of Poland. Totally, 1,013 birds from 122 flocks were examined. The presence of goose parvovirus (GPV), goose haemorrhagic polyomavirus (GHPV), and goose circovirus (GoCV) was detected by triplex PCR. The presence of GPV DNA was shown in 36 flocks. The disease was most frequently diagnosed in goslings aging 3.5 weeks (ten flocks), and 2.5 weeks (six flocks). The analysis of the nucleotide sequence of VP1 encoding region has shown close similarity of Polish GPV strains within the group which ranged from 92% to 100%. Moreover, the similarity level of these strains with GPV isolated in Europe was from 91.3% to 100%. The occurrence of GoCV DNA was shown in 25 goose flocks. The presence of GoCV DNA was found among geese aged from 2 to 6 weeks, but predominantly in those aging 3.5 (three flocks) and 5 weeks (five flocks). The sequence analysis of PCR products from the sequenced region of ORFC1 capsid protein of GoCV has shown that Polish isolates share from 85% to 91% similarity with the sequences of GoCV strains isolated in other countries. The presence of DNA of GHPV was found in 3-week-old geese. During the last 2 years the presence of GHPV was confirmed in three flocks of goslings at the age from 3 to 3.5 weeks. During the last 12 years the occurrence of co-infection with GPV and GoCV was detected in six flocks aging from 5 to 6 weeks.

Loop-mediated isothermal amplification for the detection of goose circovirus

BackgroundGoose circovirus (GCV) presents an immunosuppressive problem in production of geese. The infection’s clinical symptoms include growth retardation or feathering disorders but the infection process may remain non-symptomatic what makes the infected birds more susceptible for secondary viral, bacterial and fungal infections. Diagnosis of GCV infection is made by histopathological examination, dot blot hybridization, polymerase chain reaction (PCR) and real-time PCR. However these techniques require application of thermocyclers and qualified staff which may be cost-consuming for some diagnostic units. The aim of this study was to develop loop-mediated isothermal amplification assay (LAMP) as a simple method of GCV detection.ResultsThe presented study has shown LAMP as a rapid tool of detecting DNA of goose circovirus (GCV) as soon in 30 min time. The method used three sets of primers: two outer primers (F3 and B3), two inner primers (FIP and BIP) and two loop primers (FL and BL) to accelerate the reaction. The optimum reaction temperature and the time were 61°C for 30 min, respectively. The results were analysed using SYBR Green dye and GelRedTM solutions. Thirty-eight isolates of GCV collected from geese flocks in Poland were examined. For comparison, real-time polymerase chain reaction with F3 and B3 primers and SYBR Green dye was conducted. The obtained results have shown GCV-LAMP as a sensitive, rapid and specific assay and alternative for PCR-based methods.ConclusionsThe developed technique due to its simplicity may be applied by any veterinary laboratory or even mobile diagnostics units for the routine detection of GCV.

Astroviruses associated with stunting and pre-hatching mortality in duck and goose embryos

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 development of a rapid SYBR Green I-based quantitative PCR for detection of Duck circovirus

This report describes a one-step real-time polymerase chain reaction assay based on SYBR Green I for detection of a broad range of duck circovirus (DuCV). Align with all DuCV complete genome sequences and other Genus Circovirus download from the GenBank (such as goose circovirus, pigeon circovirus), the primers targets to the replicate gene of DuCV were designed. The detection assay was linear in the range of 1.31 × 102-1.31 × 107 copies/μL. The reaction efficiency of the assay using the slope (the slope was -3.349) and the Y-intercept was 37.01 from the linear equation was estimated to be 0.99 and the correlation coefficient (R2) was 0.993. A series of experiments were carried out to assess the reproducibility, sensitivity, and specificity of the assay, following by the low intra-assay and inter-assay CVs for CT values obtained with the standard plasmids. The intra-assay CVs were equal or less than 1.89% and the inter-assay CVs were equal or less than 1.26%. There was no cross-reaction occurred with nucleic acids extracted from RA (Riemerella anatipestifer), E. coli (Escherichia coli), Duck Cholera (Pasteurella multocida), Avian influenza virus, avian paramyxovirus, Muscovy duck parvovirus, Duck reovirus, Duck hepatitis A virus as control templates. The nucleic acids extracted from samples of healthy ducks were used as negative controls. The assay was specific and reproducible. The established real time PCR was used to detect 45 DuCV-negative samples, which were tested using conventional PCR under the developed optimal conditions, each 15 for embryonated eggs, non-embryonated budgerigar eggs, newly hatched duck, the mixture of the lung, liver, spleen which were analysis for the presence of DuCV DNA, to conform that whether the DuCV can be transmitted vertically. Meanwhile, no positive result was shown by the real-time PCR method. The SYBR Green I-based quantitative PCR can therefore be practically used as an alternative diagnostic tool and a screening method for ducks infected with duck circovirus.

Pathological observations of an experimental infection of geese with goose circovirus

There is so far no report describing the pathogenicity of goose circovirus (GoCV) following experimental infection. We report here an experimental inoculation of 21-day-old geese with a GoCV polymerase chain reaction (PCR)-positive sample of bursa of Fabricius (BF) homogenate, and the results of clinicopathological changes. Forty geese were randomly assigned to two groups: the inoculated group (n=30) receiving tissue homogenate and the uninoculated group (n=10) receiving a placebo (physiological saline). Tissue samples were collected for histopathological examination and GoCV detection. The main clinical signs in the GoCV-inoculated geese included diarrhoea at 17 to 30 days post inoculation, marked differences of growth rate and feather disorders in three of the geese. Viraemia was detected by PCR only at 14 days post inoculation. The BF, thymus, spleen, duodenum and liver of some inoculated geese were also PCR-positive. Real-time PCR showed that there was relatively more viral load in the BF. Histological examination revealed lymphocytic depletion and histiocytosis in the BF and inflammation characterized by lymphatic infiltration in the lung, liver and kidney. Immunohistochemistry applied to PCR-positive samples showed that in only three BF samples was GoCV antigen detected in lymphocytes in both the cortex and medulla. In situ apoptosis detection of all BF samples indicated that GoCV inoculation was associated with an increase in bursal lymphocytic apoptotic events.

Detection of a novel circovirus in mute swans ( Cygnus olor) by using nested broad-spectrum PCR

Circoviruses are the causative agents of acute and chronic diseases in several animal species. Clinical symptoms of circovirus infections range from depression and diarrhoea to immunosuppression and feather disorders in birds. Eleven different members of the genus Circovirus are known so far, which infect pigs and birds in a species-specific manner. Here, a nested PCR was developed for the detection of a broad range of different circoviruses in clinical samples. Using this assay, a novel circovirus was detected in mute swans ( Cygnus olor) found dead in Germany in 2006. Sequence analysis of the swan circovirus (SwCV) genome, amplified by multiply primed rolling-circle amplification and PCR, indicates that SwCV is a distinct virus most closely related to the goose circovirus (73.2% genome sequence similarity). Sequence variations between SwCV genomes derived from two different individuals were high (15.5% divergence) and mainly confined to the capsid protein-encoding region. By PCR testing of 32 samples derived from swans found dead in two different regions of Germany, detection rates of 20.0 and 77.3% were determined, thus indicating a high incidence of SwCV infection. The clinical significance of SwCV infection, however, needs to be investigated further.

Genome analysis and epidemiological investigation of goose circovirus detected in eastern China

Goose circovirus (GoCV), a potential immuno-suppressive virus, was detected in a sample collected from Yongkang avian influenza (AI) case in Zhejiang Province of eastern China. Further, epidemiological investigation showed that, four farms located in the two major rearing areas of Yongkang and Xiangshan out of eight in Zhejiang Province were positive for GoCV. However, the geese in these GoCV positive farms exhibited no apparent clinical abnormality. The complete genomes of ten isolates from Yongkang AI case (yk1) and other four different farms were sequenced. They had 90.8-99.9% nucleotide (nt) identity with each other and had 91.3-95.8% nt identity to that of the Taiwan and German strains. Genome analysis showed that the GoCVs isolated in Zhejiang Province possessed common features of circovirus, including the potentially replication-associated stem-loop structure, the Rep protein motifs, etc. Highly variable region was also detected between nt27 and nt72 in the intergenic region. Phylogenetic analysis showed that GoCVs could be divided into three distinct genetic groups, where groups I and II could each be further divided into two subgroups (I1, I2 and II1, II2, respectively). No obvious characteristic was found between subclinical strains and clinical strains. However, both the phylogenetic result and analysis of highly variable region revealed that GoCVs isolated from different locations had some geographically dependent characteristics. This is the first epidemiological investigation of GoCV in the mainland of China.