High-density SNP chips have been demonstrated to be effective instruments for simultaneously genotyping large numbers of loci, thereby facilitating genome-scale analyses and advancing genomic selection (GS) in poultry and livestock. The meat-type duck, an economically valuable poultry species in China, has so far lacked precise and high-throughput genotyping systems, which has constrained the broader implementation of GS and genome-wide association analyses (GWASs) and consequently slowed genetic progress. In this study, we developed and validated a novel SNP array based on Genotyping-by-Targeted-Sequencing (GBTS) technology. The array comprises 40,875 SNP markers evenly distributed across 32 duck chromosomes. Using data generated from this array, genomic heritability estimates were obtained for six economic traits in a cultured duck population (n = 400), with values of 0.61 ± 0.09, 0.69 ± 0.08, 0.80 ± 0.08, 0.11 ± 0.09, 0.14 ± 0.08, 0.31 ± 0.09 for age at first egg (AFE), egg production number at 38 weeks (EN38w), egg weight at 38 weeks (EW38w), body weight at 35 days (BW35d), shank length at 35 days (SL35d) and thickness of breast muscle at 40 days (TB40d). A total of 163 significant SNPs associated with economic traits were identified through GWAS, and annotation revealed 28 candidate genes related to five of these traits. Moreover, the prediction accuracy of ssGBLUP for AFE, EN38w, EW38w, BW35d, SL35d, and TB40d reached 0.55 ± 0.16, 0.56 ± 0.12, 0.57 ± 0.08, 0.25 ± 0.19, 0.31 ± 0.19, and 0.47 ± 0.17, respectively—values that exceeded those obtained using BLUP. Population genomic analyses of 400 ducks demonstrated that this SNP array provides improved genomic prediction accuracy over pedigree-based BLUP for most analyzed traits. Overall, the developed SNP array provides a robust, high-efficiency, and cost-effective genotyping platform that will accelerate genetic progress and promote the sustainable development of the meat-type duck industry.

IntroductionSince its initial isolation from chickens, Riemerella anatipestifer has emerged as an increasingly prevalent pathogen in major poultry-producing regions, causing substantial economic losses, particularly through reduced egg production.MethodsIn the present study, an epidemiological investigation was conducted to detect coinfected pathogens in R. anatipestifer-positive clinical samples. Based on the epidemiological findings, the impact of coinfection with infectious bronchitis virus (IBV) on the pathogenicity of R. anatipestifer was evaluated in specific-pathogen-free (SPF) chickens.ResultsEpidemiological analysis revealed that IBV was the most frequently detected coinfecting pathogen (11.43%) in R. anatipestifer-positive samples. Animal challenge experiments demonstrated that bacterial loads in the liver, spleen, and brain were significantly higher in coinfected chickens than in those infected with R. anatipestifer alone. Notably, the incidence of oviduct obstruction was markedly elevated in the coinfected group (100%) compared to the group infected solely with R. anatipestifer (40%).DiscussionThese results suggested that IBV coinfection exacerbated the pathogenicity of R. anatipestifer in chickens. These findings highlight the critical role of polymicrobial interactions in modulating bacterial virulence and provide a foundation for developing integrated control strategies against R. anatipestifer.

Duck Hepatitis A Virus Type 1 (DHAV-1) is a major pathogen in ducklings, characterized by severe hepatomegaly and punctate hepatic hemorrhage. In this study, we investigated host gene expression dynamics in specific-pathogen-free (SPF) ducklings infected with the DHAV-1 isolate HA5 using high-throughput RNA sequencing (RNA-seq). We performed comprehensive transcriptomic analyses, integrating Clusters of Orthologous Groups (COG) classification, Gene Ontology (GO) annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. By combining these data with viral replication kinetics, we aimed to elucidate the molecular mechanisms of DHAV-1 pathogenesis. Differentially expressed genes (DEGs) were identified at 6, 12, 24, and 48 h post-infection (hpi). Viral titers peaked at 24 hpi and declined by 48 hpi, correlating with the observed transcriptional changes. The most pronounced transcriptional response occurred at 24 hpi, with 4,067 DEGs detected. Functional enrichment analyses revealed that these DEGs were predominantly associated with immune and metabolic pathways, including the Jak-STAT signaling pathway, oxidative phosphorylation, and Toll-like receptor signaling pathway. Collectively, these findings highlight the complex interplay between host immune responses and metabolic reprogramming. This study provides novel insights into the molecular basis of DHAV-1-induced liver pathology.

IntroductionThe Picornaviridae family is a large group of viruses comprising 68 genera. Duck-origin picornaviruses are categorized into four genera, however, the taxonomic status of some recently identified strains remains to be determined.MethodsIn this study, two virus strains isolated from breeding ducks experiencing reduced egg production were identified and characterized through viral metagenomic analysis.ResultsTwo viral strains (NC0246 and PX0394) exhibiting the typical picornavirus-like genomic structure were identified and characterized. Notably, both strains exhibit extended 2A sequences that each possesses seven distinct 2A polypeptides considered rare in Picornaviridae family. Specifically, NC0246 exhibits a deletion of 73 amino acids (aa) in the region corresponding to 2A4-2A5 when compared to PX0394 indicating the genetic diversity of picornaviruses. Homology analysis revealed that the P1 region of NC0246 was most closely related to duck aalivirus A1, with aa identity of 37.37%. Conversely, the P1 region of PX0394 was most closely related to duck egg-reducing syndrome virus (DERSV), with aa identity of 64.44%. Furthermore, the 2C and 3D proteins of NC0246 and PX0394 was most closely related to DERSV. Phylogenetic analyses indicate that NC0246 and PX0394 form a sister clade to DERSV and duck aalivirus A1 and display marked heterogeneity in the P1 protein. While NC0246 and PX0394 branch nearest to DERSV and duck aalivirus A1, duck hepatitis A virus types 1 and 3, sharing secondary homology, occupy a separate lineage.ConclusionTwo picornaviruses were identified and characterized from breeding ducks that exhibited decreased egg production. Through genomic structure and homology analysis, these viruses were most closely related to DERSV and duck aalivirus A1. NC0246, PX0394, and the previously reported DERSV show a close evolutionary relationship with the genus Aalivirus based on genomic and phylogenetic analyses, suggesting a potential affiliation with this genus.

Fowl adenoviruses (FAdV) infections have been reported in numerous countries worldwide. The hepatitis-hydropericardium syndrome (HHS) caused by FAdV-4 infection has inflicted enormous economic losses on the poultry industry in China, but it has been effectively controlled with the advancement of vaccine development. Currently, the main disease affecting poultry industry is chicken inclusion body hepatitis (IBH). FAdV strain XH2109, isolated from the liver of an IBH-affected broiler, was identified as a recombinant strain between FAdV-8a and -8b through whole-genome sequencing and recombination analysis. Additionally, this strain exhibited significant genetic divergence in the penton, hexon, fiber, hexon assembly protein 100K and GAM-1protein. Pathogenicity evaluation of XH2109 strain was conducted using 10-day-old specific pathogen-free (SPF) chickens. The results demonstrated that the XH2109 strain did not cause chicken mortality, but it significantly inhibited the growth of chickens and caused obvious lesions to the liver, spleen, bursa of Fabricius, and thymus. Antiserum against the XH2109 strain was prepared, and a neutralization test was performed using chicken embryos. It was found that this antiserum could effectively neutralize FAdV-8a and FAdV-8b. Collectively, these findings improve the current understanding of the genetic diversity of FAdV in China and provide valuable insights for the development of vaccines against IBH.

Since the emergence of short beak and dwarfism syndrome (SBDS) among Cherry Valley ducks in China, duck carcasses associated with residual feather burrs have been frequently noticed. Novel goose parvovirus (NGPV) DNAs have been detected in the skins of these carcasses, however, whether NGPV present in these carcass skins is still viable remains unclear. In this study, skin samples were collected from duck carcasses with feather burrs at a local slaughterhouse. These samples were homogenized, and the sterilized homogenates were used to inoculate 9-day-old embryonated Cherry Valley duck eggs for viral isolation. Two NGPV isolates, designated as TX2302 and TX2309, were obtained and passaged in embryonated duck eggs. Their genomes were amplified by PCR, and the complete genome sequences were determined. In the phylogenetic tree constructed based on the coding protein sequences, TX2302 and TX2309 showed a closer genetic relationship with the NGPV strains isolated between 2019 and 2023. Experimental infection of 8-day-old Cherry Valley ducks with TX2302 reproduced clinical feathering disorders. Moreover, NGPV was detected in skins of the infected ducks until they reached 29 days of age. Overall, these results confirm the presence of infectious NGPV in the skin of duck carcass with feather burrs. Moreover, they demonstrate that NGPV infection alone can cause feathering disorders, potentially contributing to the formation of feather burrs in duck carcass.

Duck enteritis virus (DEV) was identified as the etiological agent responsible for an outbreak of morbidity and mortality in adult ducks on a farm in Jiangsu, China. Diagnostic approaches confirmed that the outbreak was caused by the highly pathogenic DEV-JS2024 isolate. The clinical progression of the disease, characterized by lethargy, anorexia, ocular discharge, and high mortality, was accompanied by extensive hemorrhagic lesions in critical organs such as the liver, spleen, lungs, and bursa of Fabricius, consistent with known signs of DEV infection. Genomic analysis of DEV-JS2024 revealed a 45% G+C content and 76 open reading frames. BLASTn analysis revealed that the genome of DEV-JS2024 shares the highest sequence similarity with the Chinese virulent strain CV and the DEV attenuated vaccine strain C-KCE in the database. These results indicate a close genetic relationship between DEV-JS2024 and both the virulent and attenuated strains, suggesting potential similarities in their genomic architecture. Comparative genomic analysis identified 28 nucleotide mutations, including 15 non-synonymous mutations potentially related to virulence factors. The study also highlighted the first reported 528 base pairs deletion in the UL2 gene of a virulent strain, challenging its utility as a marker for distinguishing virulent from attenuated strains. Phylogenetic analysis suggested that DEV-JS2024 May result from recombination between the vaccine and virulent strains, further complicating our understanding of DEV pathogenicity. This study provides new insights into the molecular evolution of DEV and stresses the importance of continued genomic surveillance to enhance vaccine development and control measures for duck plague.

The increasing Riemerella anatipestifer infection in chickens presents an emerging threat to the poultry industry. In the present study, we analyzed R. anatipestifer infection in chickens, including commercial layers, broiler breeders, broilers, and layer breeders, in 2024. The chicken-derived strain SD24-17-C was isolated from infected broilers and characterized. In vitro assays revealed the enhanced capabilities of SD24-17-C for adhesion and invasion to primary chick embryo fibroblasts; moreover, its reduced susceptibility to chicken serum was detected. These findings indicate enhanced infectivity of the strain in chickens. Based on the in vivo infection assay and associated clinical symptoms, mortality, organ indices, and histopathological features, we detected that the pathogenicity of SD24-17-C was lower in chickens than in ducks. Analyses of immune-related cytokine expression indicated relatively higher IL-2, IL-8, IFN-γ, TLR3, and STING levels in chickens than in ducks, reflecting the potential roles of these cytokines in mediating immune responses and bacterial clearance during R. anatipestifer infection in chickens. These findings confirmed the susceptibility of chickens to R. anatipestifer and provided critical insights into associated host-pathogen interactions.

Avian reovirus (ARV) is one of the main causes of viral arthritis, tenosynovitis, malabsorption syndrome (MAS), runting-stunting syndrome, and immunodepression. In recent years, due to the emergence of new ARV strains, outbreaks of the disease have brought significant economic losses to chicken flocks. To determine the prevalence of ARV in China from 2010 to 2024, a total of 409 tissue samples from different breeding farms were collected from chickens presenting clinical signs of lameness and swollen joints in various flocks located in 18 provinces. As performed on these tissue samples, the ARV-specific reverse transcription-polymerase chain reaction (RT-PCR) assay indicated 111 ARV-positive samples with a positive rate of 27.14%. After viral isolation from the necropsied chicken samples, 69 ARV strains were isolated, and specific sigma C (σC) genes were amplified and sequenced. The sequence analysis of σC genes showed that these 69 isolates were grouped into six clusters, including 14 ARV isolates from cluster I (20.29%), 12 ARV isolates from cluster II (17.39%), 3 ARV isolates from cluster III (4.35%), 8 ARV isolates from cluster IV (11.59%), 3 ARV isolates from cluster V (4.35%), and 29 ARV isolates from cluster VI (42.03%). Except for cluster V, each of the other five clusters could be divided into two subclusters. Homology analysis showed that ARV isolates in clusters II–VI had only 50.3 to 60.8% homology with the commercial S1133 vaccine strain which is derived from cluster I. The ARVs in subcluster Ia had high homology with the S1133 vaccine strain (93.5–98.0%), while the ARVs in subcluster Ib had a low homology with the S1133 strain (73.4–76.4%). Further, the cluster VI viruses, the main epidemic genotype in China, had only 50.3–55.7% homology with the S1133 strain. The results of the pathogenicity test showed that the representative strains of the six different clusters all caused swelling of the footpads in SPF chickens, and the incidence rate was not significantly different. The present study will be helpful in the understanding the prevalence of ARV strains in China and revealed the genetic differences between the ARV isolates and the commercial vaccine strain.

A picornavirus strain of Duck/FC22/China/2017 (FC22) with an unclear taxonomic status was isolated in our laboratory in 2017. To study the biological properties of the virus, an infectious clone of the FC22 strain was successfully rescued by the infectious subgenomic amplicon method. The FC22 gene was amplified in two segments and fused with CMV and HDR after the addition of marker sites. The fusion fragment was transfected into LMH cells and passaged, and the obtained virus was named rFC22 and identified by PCR, IFA and electron microscopy. The biological characteristics of strain rFC22 were studied by inoculation with LMH cells, and the results showed that the TCID50 of rFC22 was essentially the same as that of its parent strain FC22 (1 × 106.6 TCID50/mL) and that the growth curve of rFC22 was consistent with that of its parent strain FC22. The results indicated no significant difference in the biological characteristics between the rescued strain rFC22 and its parent strain FC22. In summary, our findings suggest that a duck-derived picornavirus was successfully rescued by ISA and the method was more convenient and more successful than alternative approaches.

Corriparta virus (CORV), an arbovirus within the Orbivirus genus, exhibits a broad vertebrate host range but limited pathogenicity. In this study, we report the first isolation and characterization of a novel orbivirus genetically related to CORV, temporarily designed as novel duck orbivirus (NDORV), from Beijing ducks in Henan province, China, in 2024. Genomic characterization revealed that NDORV possesses a 10-segment double-stranded RNA (dsRNA) genome, consistent with the structural hallmarks of the Orbivirus genus, with a high genetic similarity to Parry's Lagoon virus (PLV) and CORV. To evaluate its pathogenicity, specific pathogen-free (SPF) ducks were experimentally inoculated with NDORV. Gross pathological examination revealed splenomegaly and blood stasis as primary lesions, with no mortality observed. Histopathological analysis identified tissue damage in the spleen, lungs, heart, liver, and kidneys. The highest viral loads were observed in the spleen and lungs, peaking at 3 days postinoculation (dpi). This study provides the first comprehensive characterization of a novel orbivirus genetically akin to CORV isolated from ducks in China. These findings highlight the potential prevalence of NDORV in domestic duck populations and underscore the urgency of enhanced surveillance and research on CORV-related arboviruses.

Hepatitis is a significant pathological manifestation of fowl adenovirus serotype-4 (FAdV-4) infection, which is a crucial factor contributing to the mortality of chickens. The pathophysiology of liver disease is rooted in oxidative stress. The present study aims to investigate the presence of oxidative stress during the liver lesion process in FAdV-4 infection. Specifically, one-day-old specific pathogen-free (SPF) chickens were allocated into three groups, the control group, the infection group, and the quercetin group. The quercetin group received daily oral administration of quercetin. At the age of 12 days, the chickens belonging to both the infection and quercetin groups were subjected to intramuscular injection of FAdV-4 (0.3 mL103TCID50/mL). Samples were collected from each group at 2, 4, and 6 days post-infection (dpi), and sera were collected to measure the levels of ALT and AST. A portion of liver tissue was fixed to examine the histological changes, cell apoptosis, and mitochondrial morphology, while another portion was homogenized and mitochondria were isolated. The levels of MDA, SOD, H2O2, and GSH-Px in the homogenate supernatants of livers and isolated mitochondria were measured, and the viral load in the liver was studied. And Cyt C levels in the mitochondria and cytosolic supernatant were recorded. The results showed that AST and ALT in the serum of chicken in the infection group were significantly higher than those in the control and quercetin group at 6 dpi. Obvious swelling, steatosis, necrosis, and inflammatory cell infiltration were observed in the liver of the infection group. Administered with quercetin can significantly decrease the viral load in the liver at 4 and 6 dpi. H2O2 in the liver, and MDA, H2O2, GSH and SOD levels in mitochondria in the hepatocyte of the infection group were significantly higher than those in the control and quercetin groups. Cyt C in the mitochondria of the hepatocyte of infection and quercetin groups were significantly lower than those in the control group at 2 dpi. Cyt C in the cytoplasm of the liver in chicken in the quercetin group was significantly higher than those in the control and infection groups. It was found that the outer mitochondrial membrane in hepatocytes was fractured in the infection group. The proportion of apoptotic cells in the liver in the infection groups was significantly higher than those in the control and quercetin group at 4 dpi, and that in the control group was significantly lower than in the infection and quercetin group. The results suggested that during liver injury induced by FAdV-4 infection, oxidative damage occurred obviously in the liver and mitochondria, and hepatocyte apoptosis was observed. Quercetin, as an antioxidant, can inhibit virus replication to some extent, and alleviate oxidative damage, liver damage, and the mortality caused by FAdV-4 infection.

Duck circovirus (DuCV) is a major pathogen in duck farming that causes immunosuppression and increases the susceptibility to secondary infections. This study focused on a Chinese DuCV strain, designated SDDC, which was isolated and characterized from Cherry Valley ducks in Shandong Province in 2022. The SDDC strain was successfully propagated in specific-pathogen-free (SPF) duck embryos and confirmed by transmission electron microscopy. Genomic analysis identified a complete genome of 1994 bp, with a critical amino acid mutation (I to T) at the 160th position in the Cap protein, potentially influencing viral tropism. Pathogenicity studies in 2-day-old SPF ducks revealed a multi-organ infection, with the spleen as the primary target, exhibiting the highest viral load and significant histopathological alterations. Analysis of multi-organ viral dynamics indicated a detectable viral presence across target organs as early as 3 dpi, followed by a progressive decline in viral load until day 7. A pronounced replication peak was observed on day 14, after which a gradual viral clearance occurred. This study provides critical insights into the genomics, pathogenicity, and tropism of DuCV, establishing a foundation for elucidating its infection mechanisms, and developing targeted control strategies to protect duck farming.

BackgroundIn recent years, Riemerella anatipestifer infection in chickens has markedly increased, resulting in substantial economic losses to the poultry industry. The present study was designed to assess the pathogenicity of R. anatipestifer in laying hens and to elucidate the molecular mechanisms underlying its altered virulence.MethodsRiemerella anatipestifer strains were isolated from laying hens presenting with oviduct obstruction and diminished egg production. Animal challenge experiments were conducted to evaluate the pathogenic potential of these hen-isolated strains. Genomic DNA sequences were subjected to comparative analysis to identify virulence genes differential between newly hen-derived and previous strains.ResultsThree serotypes, 1, 5, and 10, were identified using PCR and agglutination assays. Animal challenge experiments demonstrated that all three strains could induce oviduct obstruction in 30-, 60-, and 90-day-old hens. Genomic sequencing analysis revealed 18 mutated virulence genes associated with diverse virulence determinants, including type IV secretion systems (T4SSs), hemolysin, yersiniabactin (Ybt), lipooligosaccharide (LOS), lipopolysaccharide (LPS), BrkA, capsule biosynthesis, flagella, caseinolytic protease C (ClpC), FeoAB, and Vi antigens, all of which have been established as critical factors in bacterial pathogenicity.ConclusionThe findings of this study confirm an association between R. anatipestifer infection and reduced egg production in hens, and provide a foundation for elucidating the specific roles of virulence genes in the altered pathogenicity of R. anatipestifer in chickens.

Marek's disease virus (MDV), an alphaherpesvirus, causes severe immunosuppression and T cell lymphomas in chickens, known as Marek's disease (MD), an economically important poultry disease primarily controlled by vaccination. Importantly, it also serves as a comparative model for studying herpesvirus-induced tumor formation in humans. MDV encodes more than 100 genes, most of which have unknown functions. MDV LORF1 is unique to serotype I MDV (MDV-1), lacking homologs in other herpesviruses, and has not been explored yet. To this end, an infectious bacterial artificial chromosome (BAC) harboring the complete genome of the MDV-1 very virulent strain Md5 was generated, and the rescued rMd5 maintained biological properties similar to the parental virus both in vitro and in vivo. Subsequently, rMd5ΔLORF1, a recombinant Md5 virus deficient in pLORF1 expression, was generated by a frameshift mutation in the LORF1 gene. Chickens infected with rMd5ΔLORF1 exhibited a lower mortality rate and delayed bursal atrophy than those infected with the parental rMd5 and the revertant virus (rMd5-reLORF1). Consistently, viral loads of rMd5ΔLORF1 were obviously lower than those of rMd5 or rMd5-reLORF1 in the bursa, but not in the spleen. Importantly, we found that pLORF1 deficiency impairs viral replication in bursal B cells. Furthermore, we showed that pLORF1 associated with the cellular membrane, interacted with MDV structural proteins, and exhibited punctate colocalization with tegument or capsid proteins in the cytoplasm. Taken together, this study demonstrates for the first time that the MDV-1 unique gene LORF1 is involved in MDV-induced bursal atrophy but not in tumor formation.

A novel strain of duck picornavirus was isolated from duck tissue in Taian, Shandong Province, in 2017 in our laboratory. The virus was amplified in specific-pathogen-free (SPF) chicken embryos, purified and then analyzed by whole genome sequencing, which revealed a new duck-derived small RNA virus that was designated as Duck/FC22/China/2017 (FC22, GenBank accession no. MN102111) based on its genome structure and phylogenetic relationship. An in-depth study revealed that the virus grew well on the Leghorn male hepatoma (LMH) cell line. After propagation of the virus, SPF ducks were inoculated for pathogenicity tests, and their mental state, growth and development were observed after inoculation; the ducks were dissected to observe the organs and histopathological changes. A TaqMan fluorescence quantitative PCR method was utilized to detect the proliferation and shedding patterns of the virus within the ducks, while the SYBR Green I fluorescence quantitative PCR method was used to assess cytokine expression levels in the organs. The results showed that following inoculation with the FC22 strain, the mental status of the SPF ducks remained unchanged. Mild oedema was observed in some tissue organs during dissection; however, no pathological changes, such as congestion or degeneration, were noted. Histopathological analysis revealed cellular necrosis in organs, including the heart, liver, and bursa of Fabricius, as well as a reduced volume and deep staining of certain neurons in the cerebrum. Following infection, the virus titres in various organs and in cloacal swabs of the SPF ducks peaked on the first day before gradually decreasing daily. By the 10th d, the virus titres in all organs had decreased to less than 101 1 copies/mL. Additionally, notable alterations were observed in the expression levels of the cytokines IFNa, IL6, IL10, and TNFa. This indicates that the FC22 strain does not cause significant disease in ducks. This report presents the initial study on a recently discovered picornavirus, offering a thorough and methodical examination of its pathogenic characteristics and provides a reference for the clinical evaluation and scientific strategies for the prevention and treatment of this particular picornavirus.

The duck Tembusu virus (DTMUV), an emerging flavivirus, has led to severe neurological disorders and substantial economic losses in the duck industry throughout Asia. Considering South Korea’s increasing duck production and its strategic location along the East Asian–Australasian Flyway, this study aimed to assess the presence of DTMUV in South Korea to evaluate potential risks to the poultry industry. We performed a comprehensive serological survey of 1796 serum samples from broiler and breeder ducks collected between 2011 and 2023, alongside molecular detection tests on 51 duck flocks exhibiting suspected clinical signs of DTMUV infection. The absence of serological and molecular evidence for DTMUV or other flavivirus infections suggests that these viruses have not yet affected South Korean duck populations. These findings underscore the critical need for ongoing surveillance, given the virus’s potential to disrupt agriculture and pose public health risks. The study also emphasizes the importance of maintaining stringent biosecurity measures and conducting further research to monitor and prevent DTMUV transmission, particularly due to the possible role of migratory birds and other vectors in spreading zoonotic diseases.

Porcine epidemic diarrhea virus (PEDV), porcine transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and porcine rotavirus-A (PoRVA) are the four main pathogens that cause viral diarrhea in pigs, and they often occur in mixed infections, which are difficult to distinguish only according to clinical symptoms. Here, we developed a multiplex TaqMan-probe-based real-time RT-PCR method for the simultaneous detection of PEDV, TGEV, PDCoV, and PoRVA for the first time. The specific primers and probes were designed for the M protein gene of PEDV, N protein gene of TGEV, N protein gene of PDCoV, and VP7 protein gene of PoRVA, and corresponding recombinant plasmids were constructed. The method showed extreme specificity, high sensitivity, and excellent repeatability; the limit of detection (LOD) can reach as low as 2.18 × 102 copies/μL in multiplex real-time RT-PCR assay. A total of 97 clinical samples were used to compare the results of the conventional reverse transcription PCR (RT-PCR) and this multiplex real-time RT-PCR for PEDV, TGEV, PDCoV, and PoRVA detection, and the results were 100% consistent. Subsequently, five randomly selected clinical samples that tested positive were sent for DNA sequencing verification, and the sequencing results showed consistency with the detection results of the conventional RT-PCR and our developed method in this study. In summary, this study developed a multiplex real-time RT-PCR method for simultaneous detection of PEDV, TGEV, PDCoV, and PoRVA, and the results of this study can provide technical means for the differential diagnosis and epidemiological investigation of these four porcine viral diarrheic diseases.

Background/Objective: Duck virus hepatitis (DVH), caused by duck hepatitis A virus (DHAV), poses significant challenges to duck farming due to high mortality rates in young ducklings. Despite the widespread use of live attenuated vaccines, the genetic diversity within DHAV strains has diminished their cross-protection efficacy. This study aimed to evaluate the cross-protective efficacy of current DHAV-1 and DHAV-3 vaccines against genetically divergent wild strains. Methods: Phylogenetic analyses of the VP1 genes from DHAV-1 and DHAV-3 were conducted. Both DHAV-1 and DHAV-3 vaccines were tested in ducklings, with and without maternal-derived antibodies (MDA), through challenge trials with homologous and heterologous strains. Results: In the phylogenetic analysis, compared to vaccine strains, DHAV-1 and DHAV-3 field variant strains were classified into different genotypes. In ducklings without MDA, the DHAV-1 vaccine provided 60% survival against homologous strains by 2 days post-vaccination (DPV) and complete protection by 4 DPV, while survival rates against heterologous strains ranged from 40 to 60%. In ducklings with MDA, the DHAV-1 vaccine provided full protection with an additional vaccination for day-old ducklings against heterologous strains. The DHAV-3 vaccine conferred complete protection against both homologous and heterologous strains by 2 DPV, regardless of MDA presence. Conclusions: The DHAV-3 vaccine demonstrated robust cross-protection across genotypes, while the DHAV-1 vaccine showed limitations against genetically divergent strains. These findings highlight the necessity for genotype-matched vaccines and optimized immunization strategies to enhance protection against evolving DHAV field strains.

2019年,从山东某地疑似坦布苏病毒(TMUV)感染的发病鸭和发病鹅组织病料中进行病毒分离,并通过RT-PCR、间接免疫荧光试验以及基因序列分析,确定分离到1株鸭源和1株鹅源TMUV,并命名为BZ0162和WS12101.将分离株全基因组进行PCR分段扩增、测序,发现BZ0162和WS12101基因组全长包含10991个核苷酸.全基因组核苷酸同源性比较结果显示,BZ0162和WS12101之间同源性是99.5％,与其他TMUV参考毒株同源性均大于95.7％.E蛋白核苷酸和氨基酸同源性分别大于95.2％和98.0％.遗传进化分析结果显示,BZ0162和WS12101与GenBank最新公布的CHN-JL中国株以及泰国株DK/TH/CU-1亲缘关系最近,处于同一进化分支上.分别成功分离到1株鸭源和1株鹅源坦布苏病毒,为进一步探究坦布苏病毒遗传变异及跨宿主传播机制提供了材料.