Identification of a novel goose parvovirus (GPV) recombinant associated with short beak and dwarfism syndrome in Mainland China, 2015

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

BACKGROUND

Goslings 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%.

OBJECTIVES

This 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.

METHODS

Samples 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.

RESULTS

High 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.

CONCLUSIONS

Thus, GFL and GBF appear to be significantly closely related to GoCV and GPV. The geese feathers showed increasing recovery after being quarantined and disinfected.

Genetic characterization and phylogenetic analysis of duck-derived waterfowl parvovirus in Anhui province, eastern China

Recently, a novel duck-origin goose parvovirus (N-GPV) was reported to cause short beak and dwarfism syndrome in ducks. In this study, we performed complete genome sequencing and analyzed three different duck-derived parvoviruses that infected different breeds of ducks. Phylogenetic trees based on gene sequences indicated that they were classical goose parvovirus (C-GPV), Muscovy duck parvovirus (MDPV), and N-GPV. Furthermore, potential recombination events were found. These results improve our understanding of the diversity of duck-derived parvoviruses in Anhui province, eastern China, and provide a reference for the prevention of associated diseases.

Identification of recombination in novel goose parvovirus isolated from domesticated Jing-Xi partridge ducks in South China

Outbreaks of short beak and dwarfism syndrome (SBDS), caused by a novel goose parvovirus (NGPV), have occurred in China since 2015. This rapidly spreading, infectious disease affects ducks in particular, with a high morbidity and low mortality rate, causing huge economic losses. This study analyzed the evolution of NGPV isolated from Jing-Xi partridge duck with SBDS in South China. Complete genome sequences of the NGPV strains GDQY1802 and GDSG1901 were homologous with other GPV/NGPV and Muscovy duck parvovirus (MDPV) strains. Phylogenetic analysis showed that the NGPV isolated from mainland China was related to the Taiwan 82-0321v strain of GPV. In contrast to 82-0321v and the SDLC01 strain, which was first isolated from China, the two isolates showed no deletions in the inverted terminal repeat (ITR) region. Further, in these isolates, 24 amino acid sites of the replication protein were different compared to that of GPV live vaccine strain 82-0321v, and 12 sites were unique across all NGPV isolates. These isolates also showed differences in 17 amino acid sites of the capsid protein from that of 82-0321v, two of which were the same as those in MDPV. Recombination analysis identified the major parents of GDSG1901 and GDQY1802 as the NGPV-GD and NGPV-Hun18 strains, and the minor parents as the classical GPV 06-0329 and GPV LH strains, respectively. GDQY1802 and GDSG1901 are recombinant GPV-related parvovirus isolated from domesticated partridge duck. Recombination is evident in the evolution of NGPV, and as such, the use of live attenuated vaccines for NGPV requires further study.

Coinfection of novel goose parvovirus-associated virus and duck circovirus in feather sacs of Cherry Valley ducks with feather shedding syndrome

Since 2017, an infectious disease, named feather shedding syndrome (FSS), has consistently broken out in Cherry Valley ducks in East China. The sick ducks showed the new clinical symptoms of feather shedding and being plucked off with difficulty after slaughter. The high incidence rate of 20 to 70% predominantly happened in ducks of 4 to 5 wk of age, and nearly 40% mortality rate was observed in infected ducks. To explore the possible role of novel goose parvovirus–associated virus (NGPV) and duck circovirus (DuCV) in this disease, a total of 540 feather sac samples were collected from sick ducks with FSS. The infection rates of NGPV and DuCV in samples were 82.78 and 78.89%, respectively, and the coinfection rate of the 2 viruses was 70.00%. Notably, ducks of 4 to 5 wk of age usually presented obvious and severe FSS in the flocks with high codetection rate of NGPV and DuCV. Furthermore, 9 NGPV strains were isolated from feather sacs and 5 synchronous amino acid mutations were demonstrated in VP3 protein. These results indicated that coinfection of NGPV and DuCV might play an important role in duck FSS disease.

Identification of a common conserved neutralizing linear B-cell epitope in the VP3 protein of waterfowl parvoviruses

Waterfowl parvoviruses (WPVs) including goose parvovirus (GPV), novel GPV-related virus (NGPV) and Muscovy duck parvovirus (MDPV) cause significant economic losses and epizootic threat to the waterfowl industries, and little is known about the B-cell epitopes of WPVs. In this study, a monoclonal antibody (mAb) 5B5 against the VP3 protein of NGPV was used to identify the possible epitope in the three kinds of WPVs. The mAb 5B5 had neutralizing activities to the three viruses, and reacted with the conserved linear B-cell epitopes of ⁴³⁸LHNPPP⁴⁴³ in VP3 protein of GPV, NGPV and MDPV. To the authors' best knowledge, this is the first report on identification of the common conserved neutralizing linear B-cell epitope on VP3 protein of three different WPVs, which would facilitate the development of a novel immunodiagnostic assay for rapid detection of WPV infection.

Detection and Molecular Characterization of Two Genotypes of Goose Parvoviruses Isolated from Growing Period Geese and Cherry Valley Ducks in China

Goose parvovirus (GPV) is the etiologic pathogen of Derzsy's disease, causing great economic losses in the waterfowl industry. A novel GPV-related virus (NGPV), which caused short beak and dwarfism syndrome, has occurred in China since 2015. In this study, two GPV strains (RC45 and RC70) were isolated from diseased growing period geese (45 days old and 70 days old), and one NGPV strain GXN45 was isolated from a 45-day-old Cherry Valley duck in China. To better understand the genetic diversity between GPVs isolated from growing period waterfowls and other classical waterfowl parvoviruses, the complete genomes and main genes were sequenced and analyzed. Full-length genomic sequence alignments demonstrated that both RC45 and RC70 showed the highest identity with classical GPVs YZ99-6 and SHFX1201, whereas GXN45 shared the highest identity with NGPV SDLC01. Sequence alignment of the inverted terminal repeat region showed that GXN45, RC45, and RC70 had two 14-nucleotide (nt) deletions compared with the classical GPV virulent B strain and one 14-nt deletion compared with mule duck-origin NGPV M15 strain. Phylogenetic tree analysis of nonstructural and VP1 genes showed that GXN45 was clustered into a branch with NGPV QH15 strain except for the VP1 amino acid tree. Although both RC45 and RC70 formed one separate branch distinct from classic GPV isolates, they were in one large phylogenetic tree branch. This study will contribute to a better understanding of the genetic diversity and molecular characterization of three isolated parvoviruses and lay the foundation to further study the relationship between mutations of virus genome and viral pathogenicity.

Molecular evidence of goose-parvovirus-related abnormal molting in Pekin ducks

Since January 2019, abnormal molting has been observed frequently in approximately 40-day-old Pekin ducks in China. To investigate the possible involvement of a virus, we tested the prevalence of duck circovirus (DuCV), goose hemorrhagic polyomavirus (GHPyV), and goose parvovirus (GPV) in 11 molt cases in two provinces. GPV was detected in all cases, particularly in all samples collected from the feather area. The complete genome sequences of three GPV strains were determined and found to have 52 nucleotide changes relative to GPVs associated with short beak and dwarfism syndrome of Pekin ducks. These data will enhance our understanding of GPV diversity and outcomes of GPV infection in Pekin ducks.

Diagnosis and characterization of duck beak atrophy and dwarfism syndrome in Chongqing of China

Duck beak atrophy and dwarfism syndrome (BADS) is a newly emerged disease in China since 2015. In October 2017, an unidentified disease occurred in Cherry Valley ducks, Chongqing municipality, the southwest of China. The affected birds showed short beak and growth retardation clinical signs. The disease caused approximately 20.00% morbidity and serious weight loss due to retarded growth. In order to identify the causative agent of BADS, liver, spleen, lung and heart samples were collected for virus isolation, hemagglutination test, PCR identification, and partial gene sequencing. The isolated virus was tentatively named SC16. Hemagglutination test indicated that the virus was negative to chicken red blood cells. Based on the PCR and sequencing results, the causative agent of BADS was a novel duck-origin goose parvovirus (DGPV) while no another co-infection pathogen was found in this case. Further analysis could provide insights into the control strategies of DGPV in ducks.

Growth characteristics of the novel goose parvovirus SD15 strain in vitro

Background

Short beak and dwarfism syndrome (SBDS) was caused by novel goose parvovirus (NGPV)--a variant of goose parvovirus (GPV). Ducks infected with NGPV shows clinical signs including growth retardation and protrusion of the tongue from an atrophied beak. SBDS outbreak was first reported at the northern coastal provinces of China during 2015 and it was again reported in Sichuan, an inland province of China in 2016. The disease caused a huge economic loss in Chinese duck feeding industry.

Results

The SD15 strain of NGPV was isolated from liver and intestinal tract tissue samples of infected ducks. Real-time quantitative PCR (qPCR) was used to estimate viral load in embryonated eggs and cells infected with adapted virus. The data showed that duck embryo fibroblasts (DEFs) were permissive to NGPV, while goose embryo fibroblasts (GEFs) cells were not, and the copy numbers of SD15 in the allantoic fluid of infected eggs remained at 10^5.0–10^6.5 copies/ml. The adaption procession of the virus was determined via qPCR, and viral proliferation was detected through indirect fluorescent antibody assay (IFA) in DEFs. It was further determined that viral copy numbers peaked at 96 h post-inoculation (hpi), which is the best time to harvest the virus in DEFs. Cytotoxic effects and cell death were observed at 72 hpi in SD15 infected DEFs, yet SD15 did not induce apoptosis.

Conclusions

The growth characteristics of SD15 strain of NGPV determined would be beneficial for further molecular characterization of these viruses and develop potential vaccines if required.

Development of a duplex semi-nested PCR assay for detection of classical goose parvovirus and novel goose parvovirus-related virus in sick or dead ducks with short beak and dwarfism syndrome

Duck short beak and dwarfism syndrome (SBDS) is an emerging infectious disease caused by a novel goose parvovirus-related virus (NGPV) in China. Until now, it remains uncertain whether the Cherry Valley ducks and mule ducks with SBDS are co-infected with classical goose parvovirus (GPV) and NGPV. In this study, a duplex semi-nested PCR assay with high specificity and sensitivity was developed for detection of the two viruses. Using the duplex PCR assay, NGPV was tested positive in all the 15 duck flocks with SBDS, whereas classical GPV was not detected in all the 133 sick and dead ducks collected from East China. A total of 87 (91.58%) Cherry Valley ducks aged from 5 to 18days and 35 (92.11%) mule ducks aged from 17 to 25days were detected positive for NGPV. In the NGPV-positive ducks, the virus detection rates were 81.97% to 8.20% in heart, liver, spleen, lung, kidney, pancreas, bile, thymus, bursa of Fabricius, and brain. The results indicated that NGPV was prevalent in the duck flocks of East China, whereas classical GPV was not detected in Cherry Valley ducks and mule ducks with SBDS. NGPV has extensive tissue tropism in Cherry Valley duck and mule duck, which could invade both the central and peripheral immune organs and break through the blood-brain barrier of ducks.