Young Ducklings Research Articles

Codon Usage Analysis Reveals Distinct Evolutionary Patterns and Host Adaptation Strategies in Duck Hepatitis Virus 1 (DHV-1) Phylogroups.

Duck hepatitis virus 1 (DHV-1) is a major threat to the global poultry industry, causing significant economic losses due to high mortality rates in young ducklings. To better understand the evolution and host adaptation strategies of DHV-1, we conducted a comprehensive codon usage analysis of DHV-1 genomes. Our phylogenetic analysis revealed three well-supported DHV-1 phylogroups (Ia, Ib, and II) with distinct genetic diversity patterns. Comparative analyses of the codon usage bias and dinucleotide abundance uncovered a strong preference for A/U-ended codons and a biased pattern of dinucleotide usage in the DHV-1 genome, with CG dinucleotides being extremely underrepresented. Effective number of codons (ENC) analysis indicated a low codon usage bias in the DHV-1 ORF sequences, suggesting adaptation to host codon usage preferences. PR2 bias, ENC plot, and neutrality analyses revealed that both mutation pressure and natural selection influence the codon usage patterns of DHV-1. Notably, the three DHV-1 phylogroups exhibited distinct evolutionary trends, with phylogroups Ia and Ib showing evidence of neutral evolution accompanied by selective pressure, while the phylogroup II evolution was primarily driven by random genetic drift. Comparative analysis of the codon usage indices (CAI, RCDI, and SiD) among the phylogroups highlighted significant differences between subgroups Ia and Ib, suggesting distinct evolutionary pressures or adaptations influencing their codon usage. These findings contribute to our understanding of DHV-1 evolution and host adaptation, with potential implications for the development of effective control measures and vaccines.

Isolation and genetic characterization of waterfowl parvovirus in ducks in Northern Vietnam.

Short beak and dwarfism syndrome (SBDS), a highly contagious disease, has been reported in duck farms in Vietnam since 2019. In this study, we evaluated the virulence and characterized the virus obtained from SBDS cases in North Vietnam. Polymerase chain reaction was used to detect waterfowl parvovirus in ducks, and the virus from positive samples was inoculated into 10-day-old duck-embryonated eggs to reproduce the disease in young ducklings to determine the virulence and subjected to phylogenetic analysis of non-structural (NS) and VP1 gene sequences. Goose parvovirus (GPV) was isolated from ducks associated with SDBS in Vietnam. The virus Han-GPV2001 is highly virulent when inoculated into 10-day-old duck embryos and 3-day-old ducklings. The mortality rate of duck embryos was 94.35% within 6 days of virus inoculation. Inoculating 3-day-old ducks with the virus stock with 104.03 EID50 through intramuscular and neck intravenous administration resulted in 80% and 66.67% of clinical signs of SDBS, respectively, were shown. Phylogenetic analysis based on the partial NS and VP1 gene sequences revealed that the viral isolate obtained in this study belonged to novel GPV (NGPV) and was closely related to previous Vietnamese and Chinese strains. A GPV strain, Han-GPV2001, has been successfully isolated and has virulence in duck-embryonated eggs as well as caused clinical signs of SBDS in ducks. Phylogenetic analyses of partial genes encoding NS and capsid proteins indicated that the obtained GPV isolate belongs to the NGPV group.

Interleukin-2 enhancer binding factor 2 negatively regulates the replication of duck hepatitis A virus type 1 by disrupting the RNA-dependent RNA polymerase activity of 3D polymerase

The interaction between viral components and cellular proteins plays a crucial role in viral replication. In a previous study, we showed that the 3′—untranslated region (3′—UTR) is an essential element for the replication of duck hepatitis A virus type 1 (DHAV-1). However, the underlying mechanism is still unclear. To gain a deeper understanding of this mechanism, we used an RNA pull-down and a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assay to identify new host factors that interact with the 3′—UTR. We selected interleukin-2 enhancer binding factor 2 (ILF2) for further analysis. We showed that ILF2 interacts specifically with both the 3′—UTR and the 3D polymerase (3Dpol) of DHAV-1 through in vitro RNA pull-down and co-immunoprecipitation assays, respectively. We showed that ILF2 negatively regulates viral replication in duck embryo fibroblasts (DEFs), and that its overexpression in DEFs markedly suppresses DHAV-1 replication. Conversely, ILF2 silencing resulted in a significant increase in viral replication. In addition, the RNA-dependent RNA polymerase (RdRP) activity of 3Dpol facilitated viral replication by enhancing viral RNA translation efficiency, whereas ILF2 disrupted the role of RdRP in viral RNA translation efficiency to suppress DHAV-1 replication. At last, DHAV-1 replication markedly suppressed the expression of ILF2 in DEFs, duck embryo hepatocytes, and different tissues of 1 day-old ducklings. A negative correlation was observed between ILF2 expression and the viral load in primary cells and different organs of young ducklings, suggesting that ILF2 may affect the viral load both in vitro and in vivo.

Investigation of aspergillosis outbreak in young ducklings: Unraveling the role of hatcheries in Aspergillus fumigatus transmission.

Aspergillosis is a disease that affects several species of birds and causes substantial losses in the poultry business. The purpose of the investigation was to identify the pathogen responsible for a respiratory outbreak among juvenile ducklings. An epidemic of Aspergillosis infected a total of 800 Muscovy ducks that were being reared in El-Beheira Governorate. Tissue samples were obtained to isolate suspected fungi from diseased birds and the hatchery environment. In addition, identification and molecular characterization were performed on the obtained fungal isolates. Affected birds displayed acute respiratory manifestations such as difficulty breathing, gasping for air, nasal discharge, and a mortality rate of up to 28.1%. Postmortem examination revealed bronchitis, tracheitis, congested lungs, air sacculitis, severe multifocal granulomatous pneumonia, a congested, enlarged liver, and a congested kidney with nephritis. Mycological examination revealed seven Aspergillus (A.) spp. isolates from ducklings and six from hatcheries. Isolate colonial morphology and microscopical examination were as follows: A. fumigatus, A. niger, Syncephalastrum racemosum, and four untypable isolates. These isolates were further identified by polymerase chain reaction (PCR), and the internal transcribed spacers (ITSs) gene was detected. Four representative isolates were submitted for sequencing and further phylogenetic analysis. The source of duckling infection might be linked to the hatchery environment due to the observed similarity of isolates from both affected birds and the hatchery, as evidenced by phylogenetic analysis. Our findings demonstrated the significance of appropriate hatchery control in preventing infection in young ducklings. Furthermore, the use of molecular identification techniques would be helpful for tracing the source of infection and rapid diagnosis of Aspergillus in the field.

Effect of Mineral Feed Additives on the Rearing of Young Ducklings: An Experimental Study in Western Kazakhstan

Effect of Mineral Feed Additives on the Rearing of Young Ducklings: An Experimental Study in Western Kazakhstan

The effectiveness of the biologically active additive «Activio» using when feeding young ducks

Agricultural poultry has a number of biological features: intensive metabolism and rapid growth, rapid maturity and significant reproductive potential, high body temperature, resistance to many infectious diseases, etc. The scientific article presents the results of an experimental study of the effect of the biologically active additive Activio, which contains essential oils of cinnamon, rosemary, oregano and chili pepper extract, on the productive qualities of young ducks. To realize the set goal, two experimental groups of ducks were formed: 1st group - Peking ducks, 2nd group - Cherry Valley ducks, which were fed the drug Activio as part of a complete and balanced diet in terms of nutrients and energy, at the rate of 100 g ha 1 t of compound feed . It has been established that the introduction of the drug Activio into the diet of young ducks contributes to the increase in feed consumption, live weight gains and the survival of ducklings, which is primarily due to the fact that the essential oils of cinnamon, rosemary, oregano, chili pepper extract have positive, stimulating biological effects. improve the functioning of the digestive, immune, nervous systems and musculoskeletal system. During the breeding of poultry, an important indicator is the average daily feed consumption, which according to the data of the article in the period from 1 to 7 days was 27.15 g/head/day in the ducks of the first group, and 28.41 g/head/day in the ducks of the second group, and in the period from the 22nd to the 28th day, the value of the average daily feed consumption is 259.36 g/go/day in the first group, and 270.36 g/go/day in the ducks of the second group. The use of the drug Activio did not have a negative effect on the body of young ducklings and made it possible to realize the genetic potential of the productivity of ducks, which was more clearly expressed in the young ducklings of the Cherry Valley breed, which was obtained on the basis of Peking ducks through in depth selection using the paternal line 151 and maternal line 102 and has higher growth energy compared to Peking ducks. Key words: ducks, Peking breed, Cherry Valley, feed supplement, «Activio», gains, live weight, preservation.

Detection of humoral and cell mediated immune responses among breeder ducks vaccinated against riemerellosis

Riemerellosis is an infectious disease that primarily affects young ducklings, although it can infrequently be manifested in a chronic localised form in older ducks. Though an inactivated vaccine has been found to be most effective in preventing the disease in ducklings, its potency in adult breeder ducks has not been assessed yet. To investigate the same, 200 Kuttanad breeder ducks maintained in the University Poultry and Duck Farm (UPDF), Mannuthy were grouped into two, of 100 birds each, T1 being the control group and T2, the treatment (vaccinated) group. The oil-adjuvanted inactivated vaccine, prepared as per the previously standardised protocol, was administered to the T2 group in two doses, one week apart. Blood samples in serum vials, 20 each from T1 and T2, were collected on days 0, 14, 28, 56 and 90 post-immunisation (PI) whereas blood samples in heparin vials, eight each from both the groups, were collected on days 0, 14, and 28 PI. Humoral immunity (HI) and cell mediated immunity (CMI) in the adult ducks were assessed by enzyme-linked immunosorbent assay (ELISA) and lymphocyte proliferation assay (LPA), respectively. The two assays revealed that the inactivated vaccine elicited a good immune response in the adult ducks, with HI noticed until 90th day PI and an increasing CMI that peaked on 28th day PI.

Duck hepatitis A virus type 1 transmission by exosomes establishes a productive infection in vivo and in vitro

Duck hepatitis A virus type 1 (DHAV-1) infection causes an acute and highly fatal disease in young ducklings. Exosomes are nano-sized small extracellular vesicles secreted by various cells, which participate in intercellular communication and play a key role in the physiological and pathological processes. However, the role of exosomes in DHAV-1 transmission remains unknown. In this study, through RT-PCR, WB analysis and TEM observation, the complete DHAV-1 genomic RNA, partial viral proteins, and virions were respectively identified in the exosomes derived from DHAV-1-infected duck embryo fibroblasts (DEFs). The productive DHAV-1 infection was transmitted by exosomes in DEFs, duck embryos, and ducklings, and high titers of neutralizing antibodies completely blocked DHAV-1 infection but did not significantly neutralize exosome-mediated DHAV-1 infection. To the best of our knowledge, this is the first report that exosome-mediated DHAV-1 infection was resistant to antibody neutralization in vivo and in vitro, which might be an immune evasion mechanism of DHAV-1.

INFLUENCE OF POTASSIUM IODIDE ON GROWTH, DEVELOPMENT AND MEAT QUALITIES OF DUCKS OF THE CROSS «MEDEO»

The studies were carried out in Priuraje Farm on ducks of the Medeo cross. The ducklings were kept under brooders for up to 10 days with subsequent transfer to enclosures. The effect of adding potassium iodide to the main diet of ducklings was experimentally studied. It was found that the addition of the drug improves the growth, development and safety of young animals. The live weight in the experimental groups reached 2722-2834 grams by 49 days age, which is for 2-88-10.29% higher than in the control group. The drug improves the safety of young animals up to 94.66%, vs 17.74% in the control one. The best indicators of growth, development and meat qualities were obtained by adding the drug to the main diet in a dose of 0.1 mg/kg. Potassium iodide increases the pre-slaughter weight, in comparison with the control group, for 2.87-7.1% and the meat bones ratio. Also, the drug’s positive effect was established on the development of internal organs of young ducklings.

Integrated miRNA and mRNA Expression Profiles Reveal Differentially Expressed miR-222a as an Antiviral Factor Against Duck Hepatitis A Virus Type 1 Infection.

Duck hepatitis A virus 1 (DHAV-1) is a highly contagious etiological agent that causes acute hepatitis in young ducklings. MicroRNAs (miRNAs) play important regulatory roles in response to pathogens. However, the interplay between DHAV-1 infection and miRNAs remains ambiguous. We characterized and compared miRNA and mRNA expression profiles in duck embryo fibroblasts cells (DEFs) infected with DHAV-1. In total, 36 and 96 differentially expressed (DE) miRNAs, and 4110 and 2595 DE mRNAs, were identified at 12 and 24 h after infection. In particular, 126 and 275 miRNA–mRNA pairs with a negative correlation were chosen to construct an interaction network. Subsequently, we identified the functional annotation of DE mRNAs and target genes of DE miRNAs enriched in diverse Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, which may be important for virus resistance, cell proliferation, and metabolism. Moreover, upregulated miR-222a could negatively regulate DHAV-1 replication in DEFs and downregulate integrin subunit beta 3 (ITGB3) expression by targeting the 3′ untranslated region (3′UTR), indicating that miR-222a may modulate DHAV-1 replication via interaction with ITGB3. In conclusion, the results reveal changes of mRNAs and miRNAs during DHAV-1 infection and suggest miR-222a as an antiviral factor against DHAV-1.

Insights into the Genetic Evolution of Duck Hepatitis A Virus in Egypt.

Simple SummaryThe accumulation of point mutations and/or recombination between different serotypes drives the evolution of the duck hepatitis A viruses (DHAVs). Duck viral hepatitis, caused by DHAV, is a highly infectious disease that has been detected in Egypt since 1970. Low performance, nervous signs and sudden deaths of young ducklings were the main characteristics of the disease. The aim of this study was to identify the causative agent through viral and molecular detection for the causative virus. The causative virus was isolated in embryonated duck eggs (EDEs), with complete genome sequencing that indicate the clustering of our isolates reported in this study with Chinese duck hepatitis virus 1 that may help in new vaccine manufacturing and the development of a more sensitive diagnostic assays. Future studies to evaluate the potential protection of available commercial vaccines against the newly detected isolates will be needed.Duck hepatitis virus (DHV) is one of the commercially important diseases of ducklings worldwide. It is an acute and highly infectious disease of ducklings caused by three different serotypes (1–3) of duck hepatitis A virus (DHAV), and serotype 1 is the most common in poultry. To date, little is known about the prevalence and genetic characterisation of DHAV-1 in Egypt. In the current study, isolation and complete genomic analyses of DHAVs circulating in commercial duck farms in different Egyptian governorates were conducted. A total of eighteen samples were collected from six Egyptian governorates of 3–11 days old ducklings (Pekin and Mullard) with a history of nervous signs and high mortality rates. Five out of eighteen (5/18) samples were screened positive for the DHAV-1 based on the VP1 gene. These samples were individually used for virus isolation in embryonated duck embryos (EDE), followed by complete genome sequencing. Phylogenomic analyses showed that DHAV serotype I; genotype I were diversified into four different groups (1–4). Most of the recent circulating Egyptian DHAV strains are clustered within group 4, while isolates characterised within this study were clustered within group 1. Recombination analyses revealed that the emergence of a new recombinant virus—DHAV-1 strain Egypt-10/2019—through recombination. Likewise, the selective pressure analyses showed the existence, inside or near areas of the viral attachment or related functions, of positive scores highlighting the importance of natural selection and viral evolution mechanism at different protein domains. The findings of this study provide updated information on the epidemiological and genetic features of DHAV-1 strains and underscore the importance of DHAV surveillance as well as re-evaluation for currently used vaccines.

Substantial Attenuation of Virulence of Tembusu Virus Strain PS Is Determined by an Arginine at Residue 304 of the Envelope Protein.

The Tembusu virus (TMUV) PS strain, derived by several passages and plaque purifications in BHK-21 cells, displays markedly lower virulence in Pekin ducklings relative to a natural isolate of TMUV, but the potential virulence determinants and the in vivo mechanisms for substantial virulence attenuation of the passage variant remain unknown. Here, we constructed a series of chimeric and mutant viruses and assessed their virulence using a 2-day-old Pekin duckling model. We showed that residue 304 in the envelope (E) protein is the molecular determinant of TMUV virulence. Further investigations with mutant and parental viruses demonstrated that acquisition of positive charges at E protein residue 304 plays a critical role in substantial attenuation of neurovirulence and neuroinvasiveness, which is linked to enhanced binding affinity for glycosaminoglycans (GAGs). In Pekin ducklings infected by subcutaneous inoculation, an Arg at residue 304 in the E protein was shown to contribute to more rapid virus clearance from the circulation, markedly reduced viremia, and significantly decreased viral growth in the extraneural tissues and the central nervous system, relative to a Met at the corresponding residue. These findings suggest that the in vivo mechanism of virulence attenuation of the TMUV passage variant closely resembles that proposed previously for GAG-binding variants of other flaviviruses. Overall, our study provides insight into the molecular basis of TMUV virulence and the in vivo consequences of acquisition of a GAG-binding determinant at residue 304 in the E protein of TMUV.IMPORTANCE TMUV-related disease emerged in 2010 and has a significant economic impact on the duck industry. Although the disease was originally recognized to affect adult ducks, increasing evidence has shown that TMUV also causes severe disease of young ducklings. It is, therefore, essential to investigate the pathogenesis of TMUV infection in a young duckling model. The significance of our studies is in identifying E protein residue Arg304 as the molecular determinant for TMUV virulence and in clarifying the crucial role of positive charges at E protein residue 304 in virulence attenuation of a TMUV passage variant. These data will greatly enhance our understanding of the pathogenesis of TMUV infection in ducklings and have implications for development of a safe and efficient vaccine.

The Neutralizing Antibody Response Elicited by Tembusu Virus Is Affected Dramatically by a Single Mutation in the Stem Region of the Envelope Protein.

Tembusu virus (TMUV) is a mosquito-borne flavivirus that most commonly affects adult breeder and layer ducks. However, a TMUV-caused neurological disease has also been found in ducklings below 7 weeks of age, highlighting the need to develop a safe vaccine for young ducklings. In this study, a plaque-purified PS TMUV strain was attenuated by serial passage in BHK-21 cells. Using 1-day-old Pekin ducklings as a model, the virus was confirmed to be attenuated sufficiently after 180 passages, whereas the neutralizing antibody response elicited by the 180th passage virus (PS180) was substantially impaired compared with PS. The findings suggest that sufficient attenuation results in loss of immunogenicity in the development of the live-attenuated TMUV vaccine. Comparative sequence analysis revealed that PS180 acquired one mutation (V41M) in prM and four mutations (T70A, Y176H, K313R, and F408L) in the envelope (E) protein. To identify the amino acid substitution(s) associated with loss of immunogenicity of PS180, we rescued parental viruses, rPS and rPS180, and produced mutant viruses, rPS180-M41V, rPS180-A70T, rPS180-H176Y, rPS180-R313K, rPS180-L408F, and rPS180-M5, which contained residue 41V in prM, residues 70T, 176Y, 313K, and 408F in E, and combination of the five residues, respectively, of PS in the backbone of the rPS180 genome. The neutralizing antibody response elicited by rPS180-L408F and rPS180-M5 was significantly higher than those by other mutant viruses and comparable to that by rPS. Furthermore, we produced mutant virus rPS-F408L, which contained residue 408L of PS180 in the backbone of the rPS genome. The F408L mutation conferred significantly decreased neutralizing antibody response to rPS-F408L, which was comparable to that elicited by rPS180. Based on homologous modeling, residue 408 was predicted to be located within the first helical domain of the stem region of the E protein (EH1). Together, these data demonstrate that a single mutation within the EH1 domain exerts a dramatical impact on the TMUV neutralizing antibody response. The present work may enhance our understanding of molecular basis of the TMUV neutralizing antibody response, and provides an important step for the development of a safe and efficient live-attenuated TMUV vaccine.

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

Simple SummaryDuck 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.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.

Muscovy Duck Reovirus Infection Disrupts the Composition of Intestinal Microbiota in Muscovy Ducklings.

Muscovy duck reovirus (MDRV) is highlypathogenic to young Muscovy ducklings. Although MDRV infection results in ducklings' acute watery diarrhea, the effect of MDRV infection on the composition of host's intestinal microbiota remains poorly understood. This study was conducted to investigate the impacts of MDRV on the composition of Muscovy ducklings' intestinal bacterial community. Three-day-old Muscovy ducklings were inoculated with either the virulent MDRV strain MW9710 or sterile Hank's solution, respectively. The cecal microbiota was analyzed between control and mock MDRV-infected ducklings using Illumina MiSeq sequencing at 6 dpi and 17 dpi, respectively. The results indicated that MDRV infection damaged the intestinal mucosa. In addition, MDRV infection caused severe perturbations of gut microbiota by decreasing microbial richness, altering the abundance of certain genera of the gut microbiota at 6 dpi. Specifically, the relative abundance of short chain fatty acids-producing bacteria (including Shuttleworthia, Streptococcus, and Ruminococcus) was reduced in MDRV-infected ducklings than those of control group, whereas, with an enrichment of Enterobacteriaceae (including Plesiomonas, Escherichia_Shigella and Proteus). Furthermore, microbiota analysis showed that the gut microbiota dysbiosis caused by MDRV infection was basically recovered at 17 dpi. Collectively, this study demonstrated that the gut microbiota of Muscovy ducklings were altered due to MDRV infection, mainly featuring as a net loss of beneficial bacteria and a compensatory proliferation of pathogenic bacteria, which may lead to severe pathology to the intestinal mucosa, and ultimately acute diarrhea. These results will provide insights into the pathology of MDRV infection.

Antioxidant influence on poultry liver morphology and hepatocyte ultrastructure.

Background and Aim:The poultry farming development is held back by necessity to use the concentrates with the increased number of crude protein, mycotoxicoses, and subclinical infections concentration. They make a significant impact on the liver, therefore affecting its morphofunctional condition. Antioxidants use can prevent the negative influence of these factors. This study aimed to examine the impact of feed supplements containing natural antioxidants and synthetic antioxidants.Materials and Methods:The Muscovy ducks, Hungarian White geese, and quails were the study object. Birds after hatching from eggs were split into two groups: Control and two experimental. The control group (40 birds of each species) received a normal diet in accordance with the type and age. The young ducklings, goslings, and quails of the first experimental group (30 birds of each species) received water with diisopropylammonium dichloroacetate (Dironax). The young ducklings, goslings, and quails of the second experimental group (30 birds of each species) received liquid multivitamin preparation, containing organic selenium form (Solvimin Selen) from the 1st day of the postembryonic development to the age of 60 days. We performed the weighing of the young ducklings, goslings, and quails, determined the live weight, liver weight, using the electronic scales (measurement inaccuracy is 0.02 g). To conduct the morphometric, histological, and electron microscopic studies liver, we killed the birds at the age of 1 day, 15 days, a month and 2 months during the postembryonic ontogenesis.Results:The performed overall studies allowed to determine the positive influence of the antioxidants on growth and development of the meat bird, whose body mass increased by 5-10% in comparison with the control parameters. The antioxidants use prevents the development of fatty, hydropic and parenchymal degeneration, hepatocyte and epithelial cells necrosis of the bile ducts, and connective tissue proliferation with its further fibrosis.Conclusion:This study proved that it is more effective to use well-digestible, fast-acting natural polyvitaminic antioxidant complex with selenium, starting from the 1st day of the postembryonic ontogeny.

Pathogenicity of egg-type duck-origin isolate of Tembusu virus in Pekin ducklings

BackgroundTembusu virus (TMUV) usually affects adult ducks, causing a severe drop of egg production. It has also been shown to be pathogenic in commercial Pekin ducklings below 7 weeks of age. Here, we report a TMUV-caused neurological disease in young egg-type ducklings and the pathogenicity of the egg-type duck-origin TMUV isolates in meat-type Pekin ducklings.ResultsThe disease occurred in 25 to 40-day-old Jinding ducklings in China, and was characterized by paralysis. Gross lesions were lacking and microscopic lesions appeared chiefly in brain and spleen. Inoculation in embryonated duck eggs resulted in isolation of TMUV Y and GL. The clinical signs and microscopic lesions observed in the spontaneously infected egg-type ducks were repeated in Pekin ducklings by experimental infection. Notably, both Y and GL strains caused 100% mortality in the case of 2-day-old inoculation by intracerebral route. High mortalities (80 and 70%) also occurred following infection of the Y virus at 2 days of age by intramuscular route and at 9 days of age by intracerebral route.ConclusionsThese findings demonstrate that the egg-type duck-origin TMUVs exhibit high pathogenicity in Pekin ducklings, and that the severity of the disease in ducklings is dependent on the infection route and the age of birds at the time of infection. The availability of the highly pathogenic TMUV strains provides a useful material with which to begin investigations into the molecular basis of TMUV pathogenicity in ducks.

Molecular Characterization and Comparative Pathogenicity of Goose Parvovirus Isolated from Jilin Province, Northeast China.

Goose parvovirus (GPV) is a highly contagious disease caused by GPV in goslings and young Muscovy ducklings. In recent years, frequent GPV outbreaks have occurred in many regions of Jilin Province, China. In this study, to understand the immune-related characteristics of the currently prevailing GPV strains in some regions of Jilin Province, six GPV strains were isolated from six different regions of Jilin Province in 2016-2018. The results of phylogenetic analysis, clinical signs, and histopathologic analysis showed that four strains were virulent and two strains were attenuated. Specifically, we found that the two attenuated strains have the same amino acid mutation at the same position in the virus protein 3 (VP3) gene, and the virulent strains have more mutation sites than the attenuated strains. This finding suggests that changes in these sites may result in GPV replication or reduction in the immune response in goslings, thereby producing strong pathogenicity, and that attenuated strains are more conservative than virulent strains.

Assessment of the hepatocyte protective effects of gypenoside and its phosphorylated derivative against DHAV-1 infection on duck embryonic hepatocytes

BackgroundDuck viral hepatitis (DVH) is an acute disease of young ducklings with no effective veterinary drugs for treatment. Gynostemma pentaphyllum is a well-known traditional Chinese medicine that plays an important role in the treatment of various diseases. Gypenoside (GP), one of the main ingredients of Gynostemma pentaphyllum, was reported with good hepatoprotective effects. However, its low solubility limits its application in the clinics. To improve its solubility and bioactivity, a phosphorylated derivative of gypenoside (pGP) was prepared by the sodium trimetaphosphate-sodium tripolyphosphate (STMP-STPP) method. An infrared spectroscopy method was applied to analyse the structures of GP and pGP. Then, a methyl thiazolyl tetrazolium (MTT) colorimetric assay was applied to study the hepatocyte protective efficacy of these two drugs against duck hepatitis A virus type 1 (DHAV-1) infection, and qPCR, TUNEL labelling and flow cytometry methods were used to study the relevant hepatocyte protective in vitro.ResultsThe infrared spectroscopy detection results showed that the phosphorylation modification of GP was successful. The MTT colorimetric assay results showed that both GP and pGP possessed good hepatocyte protective efficacy in vitro, and pGP performed better than GP when the drug was added before or after virus inoculation. Furthermore, the qPCR results revealed that both drugs could effectively inhibit the adsorption (when adding GP and pGP pre-virus inoculation), replication and release of DHAV-1, and the viral inhibition rate of pGP was greater than that of GP. The subsequent TUNEL labelling and flow cytometry assays showed that both GP and pGP could significantly inhibit duck embryo hepatocyte apoptosis induced by DHAV-1, and the inhibition effect of pGP was much stronger than that of GP.ConclusionsGP exerts good hepatocyte protective efficacy not only by inhibiting the proliferation of DHAV-1 but also by inhibiting duck embryonic hepatocyte apoptosis induced by DHAV-1, and phosphorylation modification significantly improves the antiviral and the anti-apoptotic effects of GP. Therefore, pGP has the potential to be developed into a novel drug against DHAV-1 infection.

Identification and characterization of a novel nanobody against duck hepatitis A virus type 1

Duck virus hepatitis (DVH) caused by duck hepatitis A virus type 1 (DHAV-1) is an acute and highly contagious disease affecting young ducklings. The VP1 protein is one of the major structural proteins of DHAV-1 carries critical epitopes responsible for the induction of neutralizing antibodies. In this study, we have successfully constructed an immune phage display VHHs library against DHAV-1 with the size of 6 × 106 colonies. A nanobody (Nb) against VP1 protein of DHAV-1, named Nb25, was identified from the immunized phage display library. Nb25 could react with the conserved linear B-cell epitope of 174PAPTST179 in DHAV-1 VP1, even though Nb25 showed no neutralizing activity to DHAV-1. To the best of our knowledge, this is the first report about preparation of anti-DHAV-1 Nbs and identification of the specific conserved linear B-cell epitope of DHAV-1 with Nb, which will facilitate the serologic diagnosis of DHAV-1 infection.