Avian parvovirus: classification, phylogeny, pathogenesis and diagnosis

Novel goose parvovirus in naturally infected ducks suffering from locomotor disorders: molecular detection, histopathological examination, immunohistochemical signals, and full genome sequencing

In this study, we investigated the pathological effects of novel goose parvovirus (NGPV) infection on the skeletal muscle, brain, and intestine of naturally affected ducks suffering from locomotor dysfunction as a new approach for a deeper understanding of this clinical form. For this purpose, a total of 97 diseased ducks, representing 24 flocks of different duck breeds (14-75 days old), were clinically examined. In total, 72 tissue pools of intestine, brain, and skeletal muscle samples were submitted for molecular identification. Typical clinical signs among the examined ducks suggested parvovirus infection. Regarding postmortem examination, all examined ducks showed muscle emaciation (100%) either accompanied by congestion (34%) or paleness (66%). Slight congestion, either in the brain (82.5%) or intestine (75.25%), was predominantly detected. Based on molecular identification, the intestine had the highest percentage of positive detection (91.7%), followed by the skeletal muscle (70.8%), and the brain (20.8%). The main histopathological alterations were myofibre atrophy and degeneration, marked enteritis accompanied by lymphocytic infiltration in the lamina propria and submucosa, while the affected brains showed vasculitis, diffuse gliosis, and Purkinje cell degeneration in the cerebellum. Next-generation sequencing further confirmed the presence of a variant strain of goose parvovirus (vGPV) that is globally known as NGPV and closely related to Chinese NGPV isolates. Using immunohistochemistry, the NGPV antigen was positively detected in the muscle fibres, enterocytes, and Purkinje cells in the cerebellum. These findings provided proof of the involvement of virus replication in the locomotor disorders linked to NGPV infection in ducks.

Goose parvovirus, goose hemorrhagic polyomavirus and goose circovirus infections are prevalent in commercial geese flocks in Poland and contribute to overall health and production outcomes: a two-year observational study

BACKGROUND

The intensification of poultry production and the constantly growing number of geese flocks in Poland increases the risk of infectious diseases. The study aimed to determine the health status of commercial geese, with particular emphasis on infections with goose parvovirus (GPV), goose circovirus and goose hemorrhagic polyomavirus. The study monitored 27 geese flocks, ranging in size from 3,000 to 13,000 birds, over a two-year period.

RESULTS

The results showed the presence of genetic material GPV in all flocks tested, whereas GoCV and GHPV were detected in some flocks, 44.4% and 59.3% respectively. A significant number of flocks were found to be co-infected with two (74.1%) and three viruses (22.2%). Additionally, a phylogenetic analysis of GPV and GHPV was conducted based on a fragment of the virus genome, while for GoCV the phylogenetic analysis was performed on whole genome. Analysis of the vp1 gene revealed that 30.8% of the sequences obtained belonged to a variant of the virus known as novel GPV, so far attributed to short beak and dwarfism syndrome in Pekin ducks. The majority of the GoCV genomic sequences exhibited high homology to the Polish sequence, which was previously isolated from domestic geese. Only one sequence was found to be closely related to sequences from wild birds.

CONCLUSIONS

Our research indicates that viral and bacterial co-infections are a significant problem in flocks of geese. Rarely did a single factor have a clear impact on the health status of the flock. Typically, mixed viral infections, as well as bacterial complications (mainly Escherichia coli, less frequently Ehrysipelotrix rhusiopathiae, Gallibacterium anatis, and Salmonella Typhimurium), or fungal complications lead to an increase in mortality in the flock, growth diversification of birds, and thus a reduction in production rates.

Known and novel parvoviruses identified in domestic pigeons

BACKGROUND

Parvoviridae is a family of single-stranded linear DNA viruses whose members infect both vertebrate and invertebrate species of animals, causing diseases of various systems and often associated with pathology of the gastrointestinal tract. Additionally, parvoviruses are known to induce illnesses causing diarrhea in various avian species as well; however, data on their occurrence and pathology in pigeons is scarce.

RESULTS

In this study, we developed molecular biology methods to detect and quantify parvovirus genetic material in samples acquired from racing pigeons of different health status. Our intention was to determine a connection between the presence of the virus and the occurrence of clinical signs in sampled birds. The results of quantitative analysis indicate no direct association of parvoviruses with the manifestation of enteric disease in pigeons. High-throughput sequencing was performed on samples testing positive in quantitative PCR with TaqMan probe and in digital droplet PCR. It allowed us to assemble two coding-complete pigeon parvovirus genomes, one belonging to new species and referred to as pigeon parvovirus 2, and the second which is a member of species Aveparvovirus columbid1. Additionally, we analyze two coding-complete genomic sequences acquired from pigeon feces in USA, one representing species Aveparvovirus columbid1 and one being a member of Chaphamaparvovirus genus in Hamaparvovirinae subfamily.

CONCLUSIONS

This is the first report of parvovirus in pigeons outside Asia. The findings of our research emphasize the need to further explore the poorly understood biology and pathology of pigeon parvoviruses.

Molecular epidemiology of chicken and turkey parvovirus in Turkiye: high risk, genetic recombination signals, and first complete genome analysis

The aim of this study was to detect chicken parvovirus (ChPV) and turkey parvovirus (TuPV) on Turkish poultry farms and examine the molecular epidemiology of these viruses. In 2023, a total of 1,060 fecal samples were collected from 76 broiler farms and 30 turkey farms across various regions of Turkiye. The overall positivity rate was 72.3% (55/76) in broiler flocks and 70% (21/30) in turkey flocks. Among these, the positivity rate was 35% (7/20) in birds showing no signs of enteritis. The findings of this study suggest that, depending on the genetic variability of regional strains or the viral load, nested-PCR-based methods may prove more effective than single-step PCR for detecting ChPV and TuPV cases. Therefore, it is recommended to incorporate nested PCR in molecular epidemiological studies to minimize the risk of overlooking positive cases. Phylogenetic analysis of the VP1, VP2, and complete genome sequences of TUR/2023/ChPV and TR/2023/TuPV revealed that both strains clustered with American strains in distinct lineages. Analysis using the recombination detection programs RDP4.0 and SimPlot 3.5.1 strongly suggested that TUR/2023/ChPV may be a recombinant of strains from China and Brazil. Despite the observed genetic variability in the VP2 protein, an examination of B-cell epitopes showed a high degree of similarity between ChPV and TuPV strains. This study represents the first documentation of the emergence and prevalence of TuPVs in Turkiye, providing complete genome sequences for both ChPV and TuPV. Given the high prevalence and genetic diversity of these viruses and their presence in clinically asymptomatic birds, it is crucial for stakeholders in the poultry industry to implement regular flock screenings for these and similar viral pathogens. Proactive measures like these are essential for mitigating the economic impact of these important pathogens and developing effective preventive strategies.

Egyptian Novel Goose Parvovirus in Immune Organs of Naturally Infected Ducks: Next-Generation Sequencing, Immunohistochemical Signals, and Comparative Analysis of Pathological Changes Using Multiple Correspondence and Hierarchical Clustering Approach

The present study aims to better understand the nature of currently circulating GPV strains and their pathological impact on the immune system during natural outbreaks among different duck breeds in Egypt. For this purpose, 99 ducks (25 flocks) of different breeds, aged 14-75 days, were clinically examined, and 75 tissue pools from the thymus, bursa of Fabricius, and spleen were submitted for virus detection and identification. Clinical and postmortem findings were suggestive of GPV infection. Concerning the immune system organs, atrophy in the thymus (60.6%), bursa (45.5%), and spleen (38.3%) was the most common gross lesion. Microscopically, the pathological impact of the virus was exhibited by a necrotic thymic cortex with Hassall's corpuscle disintegration, the disappearance of normal bursal histological morphology accompanied by atrophied follicles and lymphocytic depletion, and apoptosis of B-lymphocytes in lymphoid follicles of the spleen. Furthermore, immunohistochemical examination revealed positive signals of the parvovirus detected in thymic lymphocytes in the cortex, bursa-dependent lymphoid follicle of the medulla, and diffuse positive expression of viral antigens in the spleen. GPV was detected in ducks using polymerase chain reaction, with the highest percentage of positive detection in the bursa of Fabricius (76%). Next-generation sequencing and phylogenetic analysis revealed that the detected virus was a variant of GPV, globally named novel GPV (NGPV), and closely related to Chinese NGPV isolates. To our knowledge, the current study is pioneering to address the immunopathological impact of NGPV among naturally infected ducks confirmed with full genome sequencing and immunohistochemical identification worldwide.

The Structural, Biophysical, and Antigenic Characterization of the Goose Parvovirus Capsid

Goose parvovirus (GPV) is an etiological agent of Derzsy's disease, afflicting geese and Muscovy ducks worldwide. Its high mortality rate among goslings and ducklings causes large losses to the waterfowl industry. Toward molecular and structural characterization, virus-like particles (VLPs) of GPV were produced, and the capsid structure was determined by cryogenic electron microscopy (cryo-EM) at a resolution of 2.4 Å. The capsid exhibited structural features conserved among parvoviruses, including surface two-fold depressions, three-fold protrusions, and five-fold channels. A structural comparison of the GPV viral protein (VP) structure with other adeno-associated viruses (AAVs), including human AAV2, AAV5, and quail AAV (QAAV), revealed unique conformations of several surface-accessible variable regions (VRs). Furthermore, the GPV capsid was found to be thermally stable at physiological pH, but less so under lower pH conditions. As a member of the genus Dependoparvovirus, GPV could also be bound by cross-reactive anti-AAV capsid antibodies that bind to the five-fold region of the viruses, as shown by native immuno-dot blot analysis. Finally, the GPV VP structure was compared to those of other bird dependoparvoviruses, which revealed that VR-III may be important for GPV and Muscovy duck parvovirus (MDPV) infection.

Specific detection of pigeon parvovirus with TaqMan real-time PCR technology

The viruses of the Parvoviridae family can infect both vertebrate and invertebrate animals. Recently, pigeon parvovirus (PiPV) was detected in the feces of wild urban pigeons. Owing to no specific detection platform for PiPV, studies on the epidemiology of PiPV are still a research gap. To achieve this goal, in this study, a TaqMan-based fluorescence quantitative PCR (TaqMan‒PCR) technique was established. The specific primers and probes used were designed on the basis of the NS gene characterization of PiPV downloaded from GenBank. After optimization, the established TaqMan‒PCR assay provides a sensitive, accurate, reliable and cost-effective platform for PiPV detection. We found that both YDPS and healthy birds can be found to have PiPV infection through field sample investigations, and we also investigated the presence of PiPV in Fujian, mainland China. Owing to the failure to propagate PiPV in embryos and cells, knowledge of PiPV replication mechanisms in birds still needs further study. In conclusion, a TaqMan-based fluorescence quantitative PCR method was developed, with the advantages of sensitivity, specificity, and reproducibility. This method can be used for further epidemiological monitoring of PiPV infection.

Overview of Recent Advances in Canine Parvovirus Research: Current Status and Future Perspectives

Canine parvovirus (CPV-2) was first identified in the late 1970s and has since become one of the most significant infectious agents affecting dogs. CPV-2 causes severe diseases such as hemorrhagic gastroenteritis and myocarditis, posing a major threat to canine health, particularly with a high mortality rate in puppies. It is globally recognized as a highly contagious and lethal pathogen. CPV is prone to rapid mutation, leading to the emergence of new variants. Despite widespread vaccination efforts, CPV remains one of the primary causes of acute gastroenteritis and death in young and juvenile dogs. Furthermore, the detection of CPV in swine populations has introduced additional challenges to its control. This review summarizes the current epidemiological status of CPV, highlighting recent advancements in diagnostic techniques and vaccine development. Additionally, it discusses the latest research on the pathogenesis of the virus and the development of antiviral agent research and proposes prevention and control suggestions for CPV under the One Health concept. In particular, there is a need to enhance surveillance of viral dynamics, accelerate the development of novel vaccines, and deepen the exploration of the underlying pathogenic mechanisms. This review aims to provide a scientific foundation for effective control of CPV and to guide future research directions.

Evidence of a highly divergent novel parvovirus in Australia's critically endangered western ground parrot/kyloring (Pezoporus flaviventris)

Detecting pathogens in endangered animal populations is vital for understanding and mitigating threats to their survival. The critically endangered western ground parrot (Pezoporus flaviventris, WGP), with a population as low as 150 individuals in Australia, faces an imminent risk of extinction. Despite this urgency, research on viral pathogens in this species remains limited. This study aimed to identify and characterise viruses present in faecal samples from seven individual WGP using a viral metagenomic approach. Analysis of the sequenced datasets revealed the presence of a novel virus belonging to the Parvoviridae family, named psittaciform chaphamaparvovirus 7 (PsChPV-7). The genome of PsChPV-7 contains typical structural and functional gene sequences found in Parvoviridae but is highly divergent, indicating its classification as a distinct species. Phylogenetic analysis placed PsChPV-7 within a unique sub-clade of the Chaphamaparvovirus genus, suggesting its evolutionary significance as an ancient lineage within this group. These findings may contribute to the development of strategic management and biosecurity plans aimed at conserving this endangered WGP.

Simultaneous detection of novel goose parvovirus and novel duck reovirus by SYBR Green I-based duplex real-time quantitative polymerase chain reaction

Co-infection with novel goose parvovirus (NGPV) and novel duck reovirus (NDRV) is common, significantly impeding duck growth and resulting in considerable economic losses within the duck farming industry. To facilitate rapid and accurate diagnosis and differentiation of these two viruses, this study developed a SYBR Green I-based duplex real-time quantitative polymerase chain reaction (qPCR) assay. This assay enabled the simultaneous detection of NGPV and NDRV by exploiting their distinct melting temperatures (Tm): 78.5 ± 0.50 °C for NGPV and 84.5 ± 0.50 °C for NDRV. No amplification was observed for other prevalent non-target duck viruses. The intra- and inter-assay coefficients of variation were less than 1.75%. The assay showed good performance with the same detection limit of 102 copies/μL for both NGPV and NDRV. The results of the clinical testing indicated that 45.3% (34/75) of the samples tested positive for NGPV, while 38.7% (29/75) were positive for NDRV. Notably, 13.3% (10/75) exhibited co-infection. These results revealed that the sensitivity of the developed method exceed that of conventional polymerase chain reaction (PCR). The developed method for the identifying of NGPV and NDRV shows good specificity, sensitivity, and repeatability, rendering it an effective tool for the simultaneous detection of co-infection with NGPV and NDRV.

Occurrence of astrovirus in young racing pigeons and genome characterization of 2 new astrovirus genomes representing 2 new species

Enteropathies are a serious concern in racing pigeons as they significantly impair performance in races and their training, and viruses are suspected to be one of the main factors. Astroviruses are well-known to be responsible for causing enteric disease in humans and various other animals including birds, although their prevalence and pathogenicity in pigeons is poorly understood. In this study, we investigated 2 groups of young racing pigeons (sick-study group and healthy-control group) to assess the correlation between the number of astrovirus genome copies in cloacal swabs and the occurrence of enteropathy. To determine this, we developed a novel TaqMan quantitative PCR (qPCR) and digital droplet PCR (ddPCR) methods for astrovirus detection and absolute quantitative analysis. We also performed high-throughput sequencing to obtain the complete genome sequences and establish the genetic similarity of the obtained strains to known astroviruses of poultry and other avian species. Two new complete genome sequences of pigeon astroviruses in the Avastrovirus genus were identified, representing 2 new species. These were found most closely related to astroviruses identified in Columbidae species and chickens. They share an average of 75.8% genome-wide pairwise identity and 57.6% and 64.6% capsid protein sequence identity with other unclassified columbid avastrovirus sequences in GenBank. Although the difference in prevalence of astrovirus in the study and control group was found statistically insignificant, there was a significant difference between the number of genome copies in positive samples from both groups. These unambiguous results leave the role of astroviruses as enteropathogenic factors in pigeons still undetermined.

Short beak and dwarfism syndrome among Pekin ducks: First detection, full genome sequencing, and immunohistochemical signals of novel goose parvovirus in tongue tissue

Novel goose parvovirus (NGPV) is continuously threatening the global duck industry, as it causes short beak and dwarfism syndrome among different duck breeds. In this study, we investigated the viral pathogenesis in the tongue of affected ducks, as a new approach for deeper understanding of the syndrome. Seventy-three, 14- to 60-day-old commercial Pekin ducks were clinically examined. Thirty tissue pools of intestine and tongue (15 per tissue) were submitted for molecular identification. Clinical signs in the examined ducks were suggestive of parvovirus infection. All examined ducks had short beaks. Necrotic, swollen, and congested protruding tongues were recorded in adult ducks (37/73, 51%). Tongue protrusion without any marked congestion or swelling was observed in 20-day-old ducklings (13/73, 18%), and no tongue protrusion was observed in 15-day-old ducklings (23/73, 32%). Microscopically, the protruding tongues of adult ducks showed necrosis of the superficial epithelial layer with vacuolar degeneration. Glossitis was present in the nonprotruding tongues of young ducks, which was characterized by multifocal lymphoplasmacytic aggregates and edema in the propria submucosa. Immunohistochemical examination displayed parvovirus immunolabeling, mainly in the tongue propria submucosa. Based on polymerase chain reaction, goose parvovirus was detected in 9 out of 15 tongue sample pools (60%). Next-generation sequencing confirmed the presence of a variant goose parvovirus that is globally named NGPV and closely related to Chinese NGPV isolates. Novel insights are being gained from the study of NGPV pathogenesis in the tongue based on molecular and immunohistochemical identification.

Molecular and Evolutionary Characteristics of Chicken Parvovirus (ChPV) Genomes Detected in Chickens with Runting-Stunting Syndrome

Chicken Parvovirus (ChPV) belongs to the genus Aveparvovirus and is implicated in enteric diseases like runting-stunting syndrome (RSS) in poultry. In RSS, chicken health is affected by diarrhea, depression, and increased mortality, causing significant economic losses in the poultry industry. This study aimed to characterize the ChPV genomes detected in chickens with RSS through a metagenomic approach and compare the molecular and evolutionary characteristics within the Aveparvovirus galliform1 species. The intestinal content of broiler flocks affected with RSS was submitted to viral metagenomics. The assembled prevalent genomes were identified as ChPV after sequence and phylogenetic analysis, which consistently clustered separately from Turkey Parvovirus (TuPV). The strain USP-574-A presented signs of genomic recombination. The selective pressure analysis indicated that most of the coding genes in A. galliform1 are evolving under diversifying (negative) selection. Protein modeling of ChPV and TuPV viral capsids identified high conservancy over the VP2 region. The prediction of epitopes identified several co-localized antigenic peptides from ChPV and TuPV, especially for T-cell epitopes, highlighting the immunological significance of these sites. However, most of these peptides presented host-specific variability, obeying an adaptive scenario. The results of this study show the evolutionary path of ChPV and TuPV, which are influenced by diversifying events such as genomic recombination and selective pressure, as well as by adaptation processes, and their subsequent immunological impact.

Opportunistic sampling of yellow canary (Crithagra flaviventris) has revealed a high genetic diversity of detected parvoviral sequences

Parvoviruses are known to be significant viral pathogens that infect a wide range of species globally. However, little is known about the parvoviruses circulating in Australian birds, including yellow canaries. Here, we present four parvoviral sequences including three novel parvoviruses detected from 10 yellow canaries (Crithagra flaviventris), named canary chaphamaparvovirus 1 and -2 (CaChPV1 and CaChPV2), canary dependoparvovirus 1 and -2 (CaDePV1 and CaDePV2). The whole genome sequences of CaChPV1, CaChPV2, CaDePV1, and CaDePV2 showed the highest identity with other parvoviruses at 76.4%, 75.9%, 84.0%, and 59.1%, respectively. Phylogenetic analysis demonstrated that CaChPV1 and CaChPV2 were clustered within the genus Chaphamaparvovirus. Meanwhile, CaDePV1 and CaDePV2 fall within the genus Dependoparvovirus and have the closest evolutionary relationship to the bird-associated dependoparvoviruses. Overall, this study enriched our understanding of the genetic diversity among avian parvoviruses within the Parvoviridae family.

Molecular Characterization of the Chicken Parvovirus Based on VP1 Gene Circulating in Brazilian Chicken Flocks

Parvovirus infection affects several animal species, especially young animals. In birds, parvovirus infection has been described in Muscovy ducks, turkeys, and chickens, all of which had enteric diseases characterized by diarrhea. Chicken parvovirus (ChPV) has been detected in poultry around the world in animals affected by enteric problems, showing dwarfism, cloacal pasting, and diarrhea. In Brazil, ChPV was detected in chickens affected by diarrhea fifteen years ago. However, the genetic characteristics of ChPV circulating in chicken flocks were not determined. Therefore, the aim of the present investigation was to determine the genetic characteristics of the VP1 gene from ChPV detected in chickens affected by enteric diseases in Brazil. For this purpose, a molecular approach was used. Specific primers were designed to flank the complete VP1 gene of ChPV and amplify it using PCR. The amplified products from samples of chickens with enteric diseases were sequenced, and 22 complete CDs of the VP1 gene were obtained. These samples, compared to the ABU-P1 sequence, showed 17 sequences with high nucleotide (NT) similarity of 92.7-97.4% and amino acid (AA) similarity of 94.8-99.5% associated with Runting and Stunting syndrome (RSS); there were also five samples associated with hens with diarrhea with unusual jejunal dilatation (JD) that had less similarity than the RSS sequences (NT of 86.5% and AA of 93-93.1%). The phylogenetic analysis determined four groups. Group I had sequences from Korea. The second group included sequences from Korea, China, and Brazil (not included in this work). The third group had studied RSS sequences grouped with the ABU-P1 strain and sequences from China and the United States. Finally, the sequences from JD were clustered in a separate group with a bootstrap of 100%, a group that was denoted as group IV, and included sequences from China. RDP4 and SimPlot analysis showed one point of recombination with the sequences of group III ChPV in the JD sequences. Herein, we show that circulating strains of ChPV exhibit genetic differences in the VP1 gene in Brazilian chicken flocks. Nevertheless, more studies are needed to determine the probability of a new genetic group of ChPV based on the analysis of the complete genome.

Development of a Double-Antibody Sandwich ELISA Based on a Monoclonal Antibody against the Viral NS1 Protein for the Detection of Chicken Parvovirus

Chicken parvovirus (ChPV) infection can cause runting-stunting syndrome (RSS) in chickens. There is currently no commercially available vaccine for controlling ChPV, and ChPV infection in chickens is widespread globally. The rapid detection of ChPV is crucial for promptly capturing epidemiological data on ChPV. Two monoclonal antibodies (mAbs), 1B12 and 2B2, against the ChPV NS1 protein were generated. A double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was developed for detecting ChPV based on the mAb 1B12 and an anti-chicken polyclonal antibody against the ChPV NS1 protein. The detection limit for the ChPV recombinant pET32a-NS1 protein was approximately 31.2 ng/mL. A total of 192 throat and cloaca swab samples were analyzed for ChPV by the established DAS-ELISA and nested PCR methods. The concordance rate between the DAS-ELISA and the nested PCR method was 89.1%. The DAS-ELISA can detect the ChPV antigen without any cross-reaction with FAdV-4, FAdV-1, NDV, AIV, MS, CIAV, aMPV, EDSV, IBV, or AGV2. The method also has high repeatability, with a coefficient of variation (CV) of less than 5%. These findings indicate that the DAS-ELISA exhibits high accuracy, good sensitivity, and specificity, making it suitable for viral detection, field surveillance, and epidemiological studies.

Development and application of a multiplex PCR method for the simultaneous detection of goose parvovirus, waterfowl reovirus, and goose astrovirus in Muscovy ducks

A multiplex polymerase chain reaction (PCR) method was developed to detect and distinguish goose parvovirus (GPV), waterfowl reovirus (WRV), and goose astrovirus (GAstV). Three pairs of primers were designed based on conserved regions in the genomic sequences of these enteric viruses and were used to specifically amplify targeted fragments of 493 bp from the viral protein 3 (VP3) gene of GPV, 300 bp from the sigma A-encoding gene of WRV, and 156 bp from the capsid protein-encoding gene of GAstV. The results showed that the primers can specifically amplify target fragments, without any cross-amplification with other viruses, indicating that the method had good specificity. A sensitivity test showed that the detection limit of the multiplex PCR method was 1 × 103 viral copies. A total of 102 field samples from Muscovy ducks with clinically suspected diseases were evaluated using the newly developed multiplex PCR method. The ratio of positive samples to total samples for GPV, WRV, and GAstV was 73.53% (75/102) for multiplex PCR and was 73.53% (75/102) for routine PCR. Seventy-five positive samples were detected by both methods, for a coincidence ratio of 100%. This multiplex PCR method can simultaneously detect GPV, WRV, and GAstV, which are associated with viral enteritis, thereby providing a specific, sensitive, efficient, and accurate new tool for clinical diagnosis and laboratory epidemiological investigations.

Metagenomic Identification of Novel Eukaryotic Viruses with Small DNA Genomes in Pheasants

A panel of intestinal samples collected from common pheasants (Phasianus colchicus) between 2008 and 2017 was used for metagenomic investigation using an unbiased enrichment protocol and different bioinformatic pipelines. The number of sequence reads in the metagenomic analysis ranged from 1,419,265 to 17,507,704 with a viral sequence read rate ranging from 0.01% to 59%. When considering the sequence reads of eukaryotic viruses, RNA and DNA viruses were identified in the samples, including but not limited to coronaviruses, reoviruses, parvoviruses, and CRESS DNA viruses (i.e., circular Rep-encoding single-stranded DNA viruses). Partial or nearly complete genome sequences were reconstructed of at least three different parvoviruses (dependoparvovirus, aveparvovirus and chaphamaparvovirus), as well as gyroviruses and diverse CRESS DNA viruses. Generating information of virus diversity will serve as a basis for developing specific diagnostic tools and for structured epidemiological investigations, useful to assess the impact of these novel viruses on animal health.

Liver virome of a Little Corella (Cacatua sanguinea) reveals coinfection with a novel parvovirus and two beak and feather disease viruses

Emerging diseases are acknowledged as a growing threat to wildlife, with the continued identification of pathogenic and potentially pathogenic viruses in avian species resulting from ongoing advances in molecular diagnostic techniques. Parvoviruses under the genus Chaphamaparvovirus (subfamily Hamaparvovirinae) are highly divergent. The detection and characterisation of parvoviruses in psittacine birds is limited. This study reports a novel parvovirus, tentatively named psittaciform chaphamaparvovirus 3 (PsChV-3) under the genus Chaphamaparvovirus, identified in an Australian free-ranging little corella (Cacatua sanguinea). The PsChV-3 genome is 4277 bp in length and encompasses four predicted open-reading frames, including two major genes, a nonstructural replicase gene (NS1), and a structural capsid gene (VP1). The NS1 and VP1 genes showed the closest amino acid identities of 78.8% and 69.7%, respectively, with a recently sequenced psittaciform chaphamaparvovirus 2 from Australian Neophema species grass parrots. In addition, the presence of two complete novel beak and feather disease (BFDV) genomes, 1993 and 1868 nt in length, respectively, were detected from the same bird. Both these BFDV genomes contained two bidirectional ORFs encoding the putative Rep and Cap proteins. Phylogenetic analysis showed that the sequenced novel BFDV genomes clustered in a distinct subclade with other BFDVs isolated from Australian cockatoos. This study contributes to the characterisation chaphamaparvoviruses and BFDV in Australian parrots and supports the need for ongoing monitoring and molecular studies into the avian virome in native Australian psittacine bird species.

Molecular characterization of emerging chicken and turkey parvovirus variants and novel strains in Guangxi, China

Avian parvoviruses cause several enteric poultry diseases that have been increasingly diagnosed in Guangxi, China, since 2014. In this study, the whole-genome sequences of 32 strains of chicken parvovirus (ChPV) and 3 strains of turkey parvovirus (TuPV) were obtained by traditional PCR techniques. Phylogenetic analyses of 3 genes and full genome sequences were carried out, and 35 of the Guangxi ChPV/TuPV field strains were genetically different from 17 classic ChPV/TuPV reference strains. The nucleotide sequence alignment between ChPVs/TuPVs from Guangxi and other countries revealed 85.2-99.9% similarity, and the amino acid sequences showed 87.8-100% identity. The phylogenetic tree of these sequences could be divided into 6 distinct ChPV/TuPV groups. More importantly, 3 novel ChPV/TuPV groups were identified for the first time. Recombination analysis with RDP 5.0 revealed 15 recombinants in 35 ChPV/TuPV isolates. These recombination events were further confirmed by Simplot 3.5.1 analysis. Phylogenetic analysis based on full genomes showed that Guangxi ChPV/TuPV strains did not cluster according to their geographic origin, and the identified Guangxi ChPV/TuPV strains differed from the reference strains. Overall, whole-genome characterizations of emerging Guangxi ChPV and TuPV field strains will provide more detailed insights into ChPV/TuPV mutations and recombination and their relationships with molecular epidemiological features.

Molecular detection and characterization of three novel parvoviruses belonging to two different subfamilies in zoo birds

Birds carry a large number of viruses that may cause diseases in animals or humans. At present, information about the virome of zoo birds is limited. In this study, using viral metagenomics, we investigated the fecal virome of zoo birds collected from a zoo in Nanjing, Jiangsu Province, China. Three novel parvoviruses were obtained and characterized. The genomes of the three viruses are 5,909, 4,411, and 4,233 nt in length, respectively, and contain four or five ORFs. Phylogenetic analysis showed that these three novel parvoviruses clustered with other strains and formed three different clades. Pairwise comparison of NS1 amino acid sequences showed that Bir-01-1 shared 44.30-74.92% aa sequence identity with other parvoviruses belonging to the genus Aveparvovirus, while Bir-03-1 and Bir-04-1 shared less than 66.87% and 53.09% aa sequence identity, respectively, with other parvoviruses belonging to the genus Chaphamaparvovirus. Each of these three viruses was identified as a member of a novel species based on the species demarcation criteria for parvoviruses. These findings broaden our knowledge of the genetic diversity of parvoviruses and provide epidemiological data regarding potential outbreaks of parvovirus disease in birds.

A Novel Dependoparvovirus Identified in Cloacal Swabs of Monk Parakeet (Myiopsitta monachus) from Urban Areas of Spain

The introduction of invasive birds into new ecosystems frequently has negative consequences for the resident populations. Accordingly, the increasing population of monk parakeets (Myiopsitta monachus) in Europe may pose a threat because we have little knowledge of the viruses they can transmit to native naïve species. In this study, we describe a new dependoparvovirus detected by metagenomic analysis of cloacal samples from 28 apparently healthy individuals captured in urban areas of Madrid, Spain. The genomic characterization revealed that the genome encoded the NS and VP proteins typical of parvoviruses and was flanked by inverted terminal repeats. No recombination signal was detected. The phylogenetic analysis showed that it was closely related to a parvovirus isolated in a wild psittacid in China. Both viruses share 80% Rep protein sequence identity and only 64% with other dependoparvoviruses identified in Passeriformes, Anseriformes, and Piciformes and are included in a highly supported clade, which could be considered a new species. The prevalence was very low, and none of the additional 73 individuals tested positive by PCR. These results highlight the importance of exploring the viral genome in invasive species to prevent the emergence of novel viral pathogenic species.

Parvovirus dark matter in the cloaca of wild birds

With the development of viral metagenomics and next-generation sequencing technology, more and more novel parvoviruses have been identified in recent years, including even entirely new lineages. The Parvoviridae family includes a different group of viruses that can infect a wide variety of animals. In this study, systematic analysis was performed to identify the "dark matter" (datasets that cannot be easily attributed to known viruses) of parvoviruses and to explore their genetic diversity from wild birds' cloacal swab samples. We have tentatively defined this parvovirus "dark matter" as a highly divergent lineage in the Parvoviridae family. All parvoviruses showed several characteristics, including 2 major protein-coding genes and similar genome lengths. Moreover, we observed that the novel parvo-like viruses share similar genome organizations to most viruses in Parvoviridae but could not clustered with the established subfamilies in phylogenetic analysis. We also found some new members associated with the Bidnaviridae family, which may be derived from parvovirus. This suggests that systematic analysis of domestic and wild animal samples is necessary to explore the genetic diversity of parvoviruses and to mine for more of this potential dark matter.

Comparative analysis reveals the long-term coevolutionary history of parvoviruses and vertebrates

Parvoviruses (family Parvoviridae) are small DNA viruses that cause numerous diseases of medical, veterinary, and agricultural significance and have important applications in gene and anticancer therapy. DNA sequences derived from ancient parvoviruses are common in animal genomes and analysis of these endogenous parvoviral elements (EPVs) has demonstrated that the family, which includes twelve vertebrate-specific genera, arose in the distant evolutionary past. So far, however, such "paleovirological" analysis has only provided glimpses into the biology of ancient parvoviruses and their long-term evolutionary interactions with hosts. Here, we comprehensively map EPV diversity in 752 published vertebrate genomes, revealing defining aspects of ecology and evolution within individual parvovirus genera. We identify 364 distinct EPV sequences and show these represent approximately 200 unique germline incorporation events, involving at least five distinct parvovirus genera, which took place at points throughout the Cenozoic Era. We use the spatiotemporal and host range calibrations provided by these sequences to infer defining aspects of long-term evolution within individual parvovirus genera, including mammalian vicariance for genus Protoparvovirus, and interclass transmission for genus Dependoparvovirus. Moreover, our findings support a model of virus evolution in which the long-term cocirculation of multiple parvovirus genera in vertebrates reflects the adaptation of each viral genus to fill a distinct ecological niche. Our findings show that efforts to develop parvoviruses as therapeutic tools can be approached from a rational foundation based on comparative evolutionary analysis. To support this, we published our data in the form of an open, extensible, and cross-platform database designed to facilitate the wider utilisation of evolution-related domain knowledge in parvovirus research.

Recombinant Muscovy Duck Parvovirus Led to Ileac Damage in Muscovy Ducklings

Waterfowl parvovirus (WPFs) has multiple effects on the intestinal tract, but the effects of recombinant Muscovy duck parvovirus (rMDPV) have not been elucidated. In this study, 48 one-day-old Muscovy ducklings were divided into an infected group and a control group. Plasma and ileal samples were collected from both groups at 2, 4, 6, and 8 days post-infection (dpi), both six ducklings at a time. Next, we analyzed the genomic sequence of the rMDPV strain. Results showed that the ileal villus structure was destroyed seriously at 4, 6, 8 dpi, and the expression of ZO-1, Occludin, and Claudin-1 decreased at 4, 6 dpi; 4, 6, 8 dpi; and 2, 6 dpi, respectively. Intestinal cytokines IFN-α, IL-1β and IL-6 increased at 6 dpi; 8 dpi; and 6, 8 dpi, respectively, whereas IL-2 decreased at 6, 8 dpi. The diversity of ileal flora increased significantly at 4 dpi and decreased at 8 dpi. The bacteria Ochrobactrum and Enterococcus increased and decreased at 4, 8 dpi; 2, 4 dpi, respectively. Plasma MDA increased at 2 dpi, SOD, CAT, and T-AOC decreased at 2, 4, 8 dpi; 4, 8 dpi; and 4, 6, 8 dpi, respectively. These results suggest that rMDPV infection led to early intestinal barrier dysfunction, inflammation, ileac microbiota disruption, and oxidative stress.

Virome in the cloaca of wild and breeding birds revealed a diversity of significant viruses

BACKGROUND

Wild birds may harbor and transmit viruses that are potentially pathogenic to humans, domestic animals, and other wildlife.

RESULTS

Using the viral metagenomic approach, we investigated the virome of cloacal swab specimens collected from 3182 birds (the majority of them wild species) consisting of > 87 different species in 10 different orders within the Aves classes. The virus diversity in wild birds was higher than that in breeding birds. We acquired 707 viral genomes from 18 defined families and 4 unclassified virus groups, with 265 virus genomes sharing < 60% protein sequence identities with their best matches in GenBank comprising new virus families, genera, or species. RNA viruses containing the conserved RdRp domain with no phylogenetic affinity to currently defined virus families existed in different bird species. Genomes of the astrovirus, picornavirus, coronavirus, calicivirus, parvovirus, circovirus, retrovirus, and adenovirus families which include known avian pathogens were fully characterized. Putative cross-species transmissions were observed with viruses in wild birds showing > 95% amino acid sequence identity to previously reported viruses in domestic poultry. Genomic recombination was observed for some genomes showing discordant phylogenies based on structural and non-structural regions. Mapping the next-generation sequencing (NGS) data respectively against the 707 genomes revealed that these viruses showed distribution pattern differences among birds with different habitats (breeding or wild), orders, and sampling sites but no significant differences between birds with different behavioral features (migratory and resident).

CONCLUSIONS

The existence of a highly diverse virome highlights the challenges in elucidating the evolution, etiology, and ecology of viruses in wild birds. Video Abstract.

Characterizing two novel goose parvoviruses with different origins

Outbreaks of short beak dwarf syndrome caused by novel goose parvovirus (NGPV) have been prevalent in China since 2015, resulting in a high mortality rate of ducks. Herein we evaluated differences between two NGPV strains: Muscovy duck-origin (AH190917-RP: MD17) and Cherry Valley duck-origin (JS191021-RP: CVD21) NGPV. Both of them showed certain level of pathogenicity to primary duck embryo fibroblasts, Cherry Valley duck embryos and ducklings. CVD21 showed comparatively stronger pathogenicity than MD17. Only CVD21 caused obvious cytopathic effect (CPE), characterized by cell shedding; further, the virus titer of MD17 and CVD21 was 10^2.571 ELD₅₀ (i.e., median embryo lethal dose)/0.2 mL and 10^6.156 ELD₅₀ /0.2 mL, respectively, and the mortality rate of CVD21- and MD17-infected Cherry Valley ducklings was 100% and 80%, respectively. In addition, CVD21 had a greater influence on the growth and development of ducklings. Futhermore, we found that MD17 could infect Muscovy duck embryos and produce lesions similar to Cherry Valley duck embryos, but it could not infect Muscovy duck embryo fibroblasts (MDEFs,) and Muscovy ducklings. MDV21 had no infection to MDEFs, Muscovy duck embryo and Muscovy ducklings. We then sequenced the complete genome of the two isolates to enable genomic characterization. The complete genome of MD17 and CVD21 was 5,046 and 5,050 nucleotides in length, respectively. Nucleotide alignment, amino acid analysis, and phylogenetic tree analysis revealed that MD17 showed higher homology to goose parvovirus (GPV), while CVD21 demonstrated stronger similarity with NGPV. Moreover, the two isolates shared 95.8% homology, with encoded proteins showing multiple amino acid variations. Our findings indicate that Muscovy ducks seem to have played a crucial role in the evolution of GPV to NGPV. We believe that our data should serve as a foundation for further studying the genetic evolution of waterfowl parvoviruses and their pathogenic mechanisms. This article is protected by copyright. All rights reserved.

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

Investigating the Diversity and Host Range of Novel Parvoviruses from North American Ducks Using Epidemiology, Phylogenetics, Genome Structure, and Codon Usage Analysis

Parvoviruses are small single-stranded DNA viruses that can infect both vertebrates and invertebrates. We report here the full characterization of novel viruses we identified in ducks, including two viral species within the subfamily Hamaparvovirinae (duck-associated chapparvovirus, DAC) and a novel species within the subfamily Densovirinae (duck-associated ambidensovirus, DAAD). Overall, 5.7% and 21.1% of the 123 screened ducks (American black ducks, mallards, northern pintail) were positive for DAC and DAAD, respectively, and both viruses were more frequently detected in autumn than in winter. Genome organization and predicted transcription profiles of DAC and DAAD were similar to viruses of the genera Chaphamaparvovirus and Protoambidensovirus, respectively. Their association to these genera was also demonstrated by subfamily-wide phylogenetic and distance analyses of non-structural protein NS1 sequences. While DACs were included in a highly supported clade of avian viruses, no definitive conclusions could be drawn about the host type of DAAD because it was phylogenetically close to viruses found in vertebrates and invertebrates and analyses of codon usage bias and nucleotide frequencies of viruses within the family Parvoviridae showed no clear host-based viral segregation. This study highlights the high parvoviral diversity in the avian reservoir with many avian-associated parvoviruses likely yet to be discovered.

Runting and Stunting Syndrome in Broiler Chickens: Histopathology and Association With a Novel Picornavirus

Runting stunting syndrome (RSS) in commercial chickens has been reported worldwide, and although several studies have attempted to clarify the cause and describe the lesions, there are gaps in knowledge of the epidemiology, pathogenesis, and etiology. The study objective was to use commercial chicks naturally affected by RSS to describe the histologic changes of RSS in all segments of the small intestine in chicks of different ages and to identify viral gene sequences in affected chicks and their association with histologic lesions. Chicks lacking clinical signs but from the same houses and from unaffected houses were used as controls. The average weight of affected chicks was significantly lower than expected for their flocks. Macroscopically, the small intestines had paler serosa, with watery, mucoid, or foamy contents and poorly digested food. Histologic lesions were characterized by necrotic crypts, crypt dilation, and flattening of the crypt epithelium. Histomorphometry of the intestines revealed villous atrophy especially in the jejunum and ileum. Histologic changes in other organs were not observed. Random next-generation sequencing of total RNA extracted from formalin-fixed paraffin-embedded tissues detected avian nephritis virus, avian rotavirus, and picornavirus in jejunal segments from 7-day-old chicks. No viruses were detected in the jejunum of 1-day-old chicks. Detection of picornaviral reads was significantly associated (P < .05) with histologic lesions of RSS. Sequence analysis of the picornavirus revealed genetic similarity with the genus Gallivirus. Using in situ hybridization for galliviral nucleic acid sequences, the signal was associated with crypt lesion severity, although signal was detected both in chicks with and without RSS.

Detection of Novel Goose Parvovirus Disease Associated with Short Beak and Dwarfism Syndrome in Commercial Ducks

Simple Summary

Duck short beak and dwarfism syndrome is an emerging infectious disease caused by a novel goose parvovirus that has been detected in Europe and China since 1974. Low performance, slow growth and deaths of young ducklings were the main characteristics of the disease. To the best of our knowledge, such syndrome has not been recorded in Egypt, but since 2019, it was observed in some mule and pekin duck farms that resulted in drastic economic losses for waterfowl producers. Identification of the causative agent through viral and molecular detection of the causative virus was the aim of this study. Also, gene sequence of one of three viral protein genes which are responsible for the virulence was accomplished. The causative virus was isolated on primary cell culture, with partial gene sequence of viral VP1 gene that indicated the viral clustering with Chinese novel goose parvoviruses that may help in new vaccine manufacturing and development of a more sensitive diagnostic assay. Future studies to evaluate potential protection of an available market vaccine against the novel virus will be useful.

Abstract

Derzsy’s disease causes disastrous losses in domestic waterfowl farms. A genetically variant strain of Muscovy duck parvovirus (MDPV) and goose parvovirus (GPV) was named novel goose parvovirus (NGPV), which causes characteristic syndrome in young ducklings. The syndrome was clinically characterized by deformity in beaks and retarded growth, called short beaks and dwarfism syndrome (SBDS). Ten mule and pekin duck farms were investigated for parvovirus in three Egyptian provinces. Despite low recorded mortality rate (20%), morbidity rate was high (70%), but the economic losses were remarkable as a result of retarded growth and low performance. Isolation of NGPV was successful on primary cell culture of embryonated duck liver cells with a clear cytopathic effect. Partial gene sequence of the VP1 gene showed high amino acids identity among isolated strains and close identity with Chinese strains of NGPV, and low identity with classic GPV and MDPV strains. To the best of our knowledge, this can be considered the first record of NGPV infections in Egypt.

Complete Coding Sequences of Three Chicken Parvovirus Isolates from the United States

Parvoviruses are commonly found in U.S. poultry and are associated with clinical disease. Here, we report the complete coding sequences of three chicken parvoviruses from broiler chickens from commercial farms in the state of Georgia.

Parvoviruses are commonly found in U.S. poultry and are associated with clinical disease. Here, we report the complete coding sequences of three chicken parvoviruses from broiler chickens from commercial farms in the state of Georgia.

Metagenomic characterisation of avian parvoviruses and picornaviruses from Australian wild ducks

Ducks can shed and disseminate viruses and thus play a role in cross-species transmission. In the current study, we detected and characterised various avian parvoviruses and picornaviruses from wild Pacific black ducks, Chestnut teals, Grey teals and Wood ducks sampled at multiple time points from a single location using metagenomics. We characterised 46 different avian parvoviruses belonging to three different genera Dependoparvovirus, Aveparvovirus and Chaphamaparvovirus, and 11 different avian picornaviruses tentatively belonging to four different genera Sicinivirus, Anativirus, Megrivirus and Aalivirus. Most of these viruses were genetically different from other currently known viruses from the NCBI dataset. The study showed that the abundance and number of avian picornaviruses and parvoviruses varied considerably throughout the year, with the high number of virus reads in some of the duck samples highly suggestive of an active infection at the time of sampling. The detection and characterisation of several parvoviruses and picornaviruses from the individual duck samples also suggests co-infection, which may lead to the emergence of novel viruses through possible recombination. Therefore, as new and emerging diseases evolve, it is relevant to explore and monitor potential animal reservoirs in their natural habitat.

Molecular Characterization and Pathogenicity of Chicken Parvovirus (ChPV) in Specific Pathogen-Free Chicks Infected Experimentally

Chicken parvovirus (ChPV) is an agent frequently associated with runting stunting syndrome (RSS). This syndrome has been reported in association with ChPV in many countries, including Brazil; however, studies characterizing the virus on a molecular level are scarce, and ChPV pathogenicity in day-old chicks remains unclear. The aim of the present work was to establish the molecular characteristics of ChPV, determine the pathogenicity of ChPV in SPF chicks and detect and quantify ChPV by qPCR in several tissues and chicks of different ages. The experimental challenge was performed at one day of age, and daily and weekly observations were performed and five birds from each experimental group (mock and infected birds) were euthanized to perform the different analysis. ChPV genome copies were detected and quantified by qPCR in gut, spleen, thymus, kidney, pancreas, proventriculus and bursa. Clinically, the infected group presented with diarrhea 24 h post-infection, which persisted until 42 days of age. The small intestine was distended, and its contents were aqueous and foamy. Enteritis and dilated crypts with cyst shapes were observed in intestinal segments. Acute pancreatitis associated with lymphocytic nodules, infiltrating lymphocytes and plasma cells between the pancreatic acinus was observed. Koch’s postulate was demonstrated and the genetic characterization of the VP1 gene showed that the Brazilian ChPV isolate belongs to the ChPV II group.

Whole Genome Characterization and Genetic Evolution Analysis of a New Ostrich Parvovirus

Ostrich diseases characterized by paralysis have been breaking out in broad areas of China since 2015, causing major damage to the ostrich breeding industry in China. This report describes a parvovirus detected in ostriches from four different regions. The entire genomes of four parvovirus strains were sequenced following amplification by PCR, and we conducted comprehensive analysis of the ostrich parvovirus genome. Results showed that the length genomes of the parvovirus contained two open reading frames. Ostrich parvovirus (OsPV) is a branch of goose parvovirus (GPV). Genetic distance analysis revealed a close relationship between the parvovirus and goose parvovirus strains from China, with the closest being the 2016 goose parvovirus RC16 strain from Chongqing. This is the first report of a parvovirus in ostriches. However, whether OsPV is the pathogen of ostrich paralysis remains uncertain. This study contributes new information about the evolution and epidemiology of parvovirus in China, which provides a new way for the study of paralysis in ostriches.

Nanobody‑horseradish peroxidase and -EGFP fusions as reagents to detect porcine parvovirus in the immunoassays

Background

Antibodies are an important reagent to determine the specificity and accuracy of diagnostic immunoassays for various diseases. However, traditional antibodies have several shortcomings due to their limited abundance, difficulty in permanent storage, and required use of a secondary antibody. Nanobodies, which are derived from single-chain camelid antibodies, can circumvent many of these limitations and, thus, appear to be a promising substitute. In the presented study, a sandwich ELISA-like immunoassay and direct fluorescent assay with high sensitivity, good specificity, and easy operation were the first time to develop for detecting porcine parvovirus (PPV). After screening PPV viral particles 2 (VP2) specific nanobodies, horseradish peroxidase (HRP) and enhanced green fluorescent protein (EGFP) fusions were derived from the nanobodies by recombinant technology. Finally, using the nanobody-HRP and -EGFP fusions as probes, the developed immunoassays demonstrate specific, sensitive, and rapid detection of PPV.

Results

In the study, five PPV-VP2 specific nanobodies screened from an immunised Bactrian camel were successfully expressed with the bacterial system and purified with a Ni–NTA column. Based on the reporter-nanobody platform, HRP and EGFP fusions were separately produced by transfection of HEK293T cells. A sandwich ELISA-like assay for detecting PPV in the samples was firstly developed using PPV-VP2-Nb19 as the capture antibody and PPV-VP2-Nb56-HRP fusions as the detection antibody. The assay showed 92.1% agreement with real-time PCR and can be universally used to surveil PPV infection in the pig flock. In addition, a direct fluorescent assay using PPV-VP2-Nb12-EGFP fusion as a probe was developed to detect PPV in ST cells. The assay showed 81.5% agreement with real-time PCR and can be used in laboratory tests.

Conclusions

For the first time, five PPV-VP2 specific nanobody-HRP and -EGFP fusions were produced as reagents for developing immunoassays. A sandwich ELISA-like immunoassay using PPV-VP2-Nb19 as the capture antibody and PPV-VP2-Nb56-HRP fusion as the detection antibody was the first time to develop for detecting PPV in different samples. Results showed that the immunoassay can be universally used to surveil PPV infection in pig flock. A direct fluorescent assay using PPV-VP2-Nb12-EGFP as a probe was also developed to detect PPV in ST cells. The two developed immunoassays eliminate the use of commercial secondary antibodies and shorten detection time. Meanwhile, both assays display great developmental prospect for further commercial production and application.

Molecular Characterization of Parvovirus Strain GX-Tu-PV-1, Isolated from a Guangxi Turkey

The aim of the current study was to determine the genomic sequence of parvovirus strain GX-Tu-PV-1, which was isolated from a turkey in Guangxi Province, South China. The analysis showed that the genome sequence of GX-Tu-PV-1 was 81.3% to ∼99.3% similar to those of other turkey parvoviruses (TuPVs) and 79.8% to ∼92.1% related to chicken parvovirus (ChPV). This study will help in understanding the epidemiology and molecular characteristics of parvovirus in turkeys.

The aim of the current study was to determine the genomic sequence of parvovirus strain GX-Tu-PV-1, which was isolated from a turkey in Guangxi Province, South China. The analysis showed that the genome sequence of GX-Tu-PV-1 was 81.3% to ∼99.3% similar to those of other turkey parvoviruses (TuPVs) and 79.8% to ∼92.1% related to chicken parvovirus (ChPV). This study will help in understanding the epidemiology and molecular characteristics of parvovirus in turkeys.