Control Ducks Research Articles

Cross-Reaction of Duck and Chicken Sera against Avian Influenza H5N1 Virus Clades 2.1.3 and 2.3.2 Antigens by Hemagglutination Inhibition Test

ABSTRACT This study aims to determine the cross-reaction between the antigen of avian influenza (AI) H5N1 virus clades 2.1.3 and 2.3.2 in duck and chicken sera, which were vaccinated with inactivated AI H5N1 clade 2.1.3 vaccine against AI H5N1 clade 2.3.2 antigen and those vaccinated with inactivated AI H5N1 clade 2.3.2 vaccine against H5N1 clade 2.1.3 antigen. The sera tested were obtained from postvaccination and control (unvaccinated) chickens and ducks in the laboratory condition, and from AI H5N1 postvaccination ducks in the field condition. HI test was conducted by using AI H5N1 clades 2.1.3 and 2.3.2 antigens. The results of HI titer were analyzed by the geometric means and by ANOVA. The results show that cross-reactions in both chicken and duck sera after AI H5N1 clade 2.3.2 vaccination tested with AI H5N1 clade 2.1.3 antigen occurred with low antibody titers, whereas in chicken and duck sera postvaccination with avian influenza H5N1 virus clade 2.1.3 showed cross-reaction with high antibody titer against clade 2.3.2 antigen. The conclusion of this study, postvaccination sera of AI H5N1 clade 2.1.3 provide better cross-reaction compared to the postvaccination sera of AI H5N1 clade 2.3.2. Keywords: sera, chicken, duck, AI H5N1, clade 2.1.3 and clade 2.3.2.

Evaluation of protection induced by Riemerella anatipestifer-E. coli O78 bacterin in white pekin ducks

SUMMARY Riemerella anatipestifer infection accounts for the most significant economic losses due to infectious disease in commercial White Pekin ducks in the United States. An inactivated bacterin and a live attenuated vaccine are approved for use against R. anatipestifer in the United States. This study aimed to evaluate the duration of protection induced by the commercial bacterin containing formalin-inactivated strains of R. anatipestifer serotype 1, 2, 5 (RA1, RA2, RA5) combined with E. coli 078 (RA-EC). Pekin ducks were vaccinated twice at 2 and 3 wk of age with 0.5 mL of RA-EC bacterin containing approximately 108 colony forming units (CFU) of E. coli and 109 CFU of RA1, RA2 and RA5 per dose (0.5 mL). Four-, 6-, and 8-week-old vaccinated and non-vaccinated control ducks were subsequently challenged with virulent strains of either: E. coli 078, RA1, RA2 and RA5. Evaluation of the vaccine protective index, histopathology, and bacteriology indicate RA-EC bacterin provides protection against virulent stains of RA1, RA2, RA5, and E. coli O78 throughout the 8-wk commercial Pekin grow-out period.

Efficacy of a Recombinant Turkey Herpesvirus H5 Vaccine Against Challenge With H5N1 Clades 1.1.2 and 2.3.2.1 Highly Pathogenic Avian Influenza Viruses in Domestic Ducks (Anas platyrhynchos domesticus).

Domestic ducks are the second most abundant poultry species in many Asian countries and have played a critical role in the epizootiology of H5N1 highly pathogenic avian influenza (HPAI).In this study, the protective efficacy of a live recombinant vector vaccine based on a turkey herpesvirus (HVT) expressing the H5 gene from a clade 2.2 H5N1 HPAI strain (A/Swan/Hungary/4999/ 2006) (rHVT-H5/2.2), given at 3 days of age, was examined in Pekin ducks (Anas platyrhynchos domesticus). The vaccine was given alone or in combination with an inactivated H5N1 clade 2.3.2.1 reverse genetic (rgGD/2.3.2.1) vaccine given at 16 days of age, either as a single vaccination or in a prime-boost regime. At 30 days of age, ducks were challenged with one of two H5N1 HPAI viruses: A/duck/Vietnam/NCVD-2721/2013 (clade 1.1.2) or A/duck/Vietnam/NCVD-1584/2012 (clade 2.3.2.1.C). These viruses produced 100% mortality in less than 5 days in nonvaccinated control ducks. Ducks vaccinated with the rgGD/2.3.2.1 vaccine, with or without the rHVT-H5/2.2 vaccine, were 90%-100% protected against mortality after challenge with either of the two H5N1 HPAI viruses. The rHVT-H5/2.2 vaccine alone, however, conferred only 30% protection against mortality after challenge with either H5N1 HPAI virus; the surviving ducks from these groups shed higher amount of virus and for longer than the single-vaccinated rgGD/2.3.2.1 group. Despite low protection, ducks vaccinated with the rHVT-H5/2.2 vaccine and challenged with the clade 1.1.2 Vietnam virus had a longer mean death time than nonvaccinated controls (P = 0.02). A booster effect was found on reduction of virus shedding when using both vaccines, with lower oropharyngeal viral titers at 4 days after challenge with either HPAI virus (P < 0.05). Neither rHVT-H5/2.2 nor standard HVT vaccine could be detected in samples collected from multiple tissues at different time points, indicting minimal levels of viral replication. In conclusion, although a minor effect on survival was observed, this study demonstrates the suboptimal protection with the rHVT-H5/2.2 vaccine given alone in Pekin ducks against H5N1 HPAI viruses and only a minor additive effect on virus shedding reduction when used with an inactivated vaccine in a prime-boost regime.

Expression of Glial Fibrillary Acidic Protein in Brain Tissues after Experimental Infection with Newcastle Disease Virus: Comparative Study between Chicken and Duck

Glial fibrillary acidic protein (GFAP) is an intermediate filament protein that is expressed by numerous cells in the central nervous system. For determine the distribution of GFAP in brain tissues of normal and infected chicken and duck we conduct this study. A twenty-three 32-day-old male white Leghorn SPF chickens and twenty-three 32-day-old male commercial ducks were divided into control group (n= 5) and infected group (n= 18) from each bird type. 9a5b Newcastle disease virus (NDV) was used for bird infection and brain tissues from all groups were fixed in neutral buffered formalin and prepared for immunohistochemical investigation of GFAP expression. The expression of GFAP in control chicken’s brain tissues is different than those of duck. While Bergmann-glia is GFAP-negative in control chickens; it appears positive in control ducks. GFAP expression in chickens is centered in the granular layer of cerebellum but in ducks it concentrated around the Purkinje cell layer. In the infected birds, numerous reactive astrocytes were observed in brain sections stained for GFAP in both chickens and ducks after 9a5b NDV infection. In chickens, GFAP-positive astrocytes were observed in the cerebellum, cerebrum, and midbrain as well as in the medulla oblongata. These changes were more prominent in areas of inflammatory response and neuronal loss. In turn, the brain tissues of infected duck express GFAP less than infected chickens. Duck brain tissues did not show any signs of inflammatory response, therefore, the expression of GFAP in duck’s brain tissues still needs farther studies to explain the real causes underlying this expression.

Identification of the Avian Pasteurella multocida phoP Gene and Evaluation of the Effects of phoP Deletion on Virulence and Immunogenicity.

Pasteurella multocida (P. multocida) is an animal pathogen of worldwide economic significance that causes fowl cholera in poultry and wild birds. Global gene regulators, including PhoP are important in regulating bacterial virulence and are good targets for developing attenuated vaccines against many pathogenic bacteria. However, the biological significance of phoP gene has not been identified in P. multocida. Here, we identified the phoP gene in P. multocida, and we evaluated the roles of phoP in P. multocida by deleting the phoP gene. The P. multocida phoP mutant exhibited similar growth curves and lipopolysaccharide and outer membrane protein profiles but displayed defective polymyxin resistance in vitro compared with the parent strain. Additionally, the phoP deletion resulted in decreased virulence. The LD50 of the ΔphoP mutant was 32- and 154-fold higher than the parent strain via the oral and intranasal routes, respectively. Transcriptome sequencing analysis showed that 161 genes were up-regulated and 173 genes were down-regulated in the absence of the phoP gene. Finally, the immunogenicity and protective efficacy of the ΔphoP mutant were evaluated. Immunized ducks produced significantly higher levels of serum IgY and bile IgA compared to the control ducks, and immunization with the ΔphoP mutant conferred 54.5% protection efficiency against challenge with the virulent P. multocida. This work provides a platform to dissect the function of phoP and develop a new vaccine against P. multocida.

Therapeutic Antiviral Effect of the Nucleic Acid Polymer REP 2055 against Persistent Duck Hepatitis B Virus Infection.

Previous studies have demonstrated that nucleic acid polymers (NAPs) have both entry and post-entry inhibitory activity against duck hepatitis B virus (DHBV) infection. The inhibitory activity exhibited by NAPs prevented DHBV infection of primary duck hepatocytes in vitro and protected ducks from DHBV infection in vivo and did not result from direct activation of the immune response. In the current study treatment of primary human hepatocytes with NAP REP 2055 did not induce expression of the TNF, IL6, IL10, IFNA4 or IFNB1 genes, confirming the lack of direct immunostimulation by REP 2055. Ducks with persistent DHBV infection were treated with NAP 2055 to determine if the post-entry inhibitory activity exhibited by NAPs could provide a therapeutic effect against established DHBV infection in vivo. In all REP 2055-treated ducks, 28 days of treatment lead to initial rapid reductions in serum DHBsAg and DHBV DNA and increases in anti-DHBs antibodies. After treatment, 6/11 ducks experienced a sustained virologic response: DHBsAg and DHBV DNA remained at low or undetectable levels in the serum and no DHBsAg or DHBV core antigen positive hepatocytes and only trace amounts of DHBV total and covalently closed circular DNA (cccDNA) were detected in the liver at 9 or 16 weeks of follow-up. In the remaining 5/11 REP 2055-treated ducks, all markers of DHBV infection rapidly rebounded after treatment withdrawal: At 9 and 16 weeks of follow-up, levels of DHBsAg and DHBcAg and DHBV total and cccDNA in the liver had rebounded and matched levels observed in the control ducks treated with normal saline which remained persistently infected with DHBV. These data demonstrate that treatment with the NAP REP 2055 can lead to sustained control of persistent DHBV infection. These effects may be related to the unique ability of REP 2055 to block release of DHBsAg from infected hepatocytes.

Efficacy Evaluation of an Inactivated Duck Tembusu Virus Vaccine.

To evaluate the potential use of an inactivated virus-based vaccine for the control and prevention of the newly emerged duck Tembusu virus infection in China, a duck Tembusu virus isolate, Tembusu-HB, was propagated in 12-day-old duck embryos and inactivated by treatment with formaldehyde. The inactivated viral antigen was emulsified with mineral oil, and five batches of the vaccine were manufactured. The immunogenicity and protection efficacy of the vaccine were evaluated in Beijing ducks and Beijing white geese. Results showed that more than 80% of immunized ducks were protected against virulent virus challenge after two intramuscular or subcutaneous injections of the inactivated vaccine, as evidenced by the negative virus isolation results. The protection is also correlated with a positive virus-specific antibody response as detected by ELISA. In contrast, none of the control ducks and geese had any detectable antibody response. Virus was isolated from all control ducks and geese after virulent virus challenge. Interestingly, a variable level of protection (20%-80%) was observed in Beijing white geese immunized twice with the same batches of vaccine, suggesting a species-specific effect of the vaccine. Overall, the results clearly suggest that the inactivated duck Tembusu virus vaccine is immunogenic and provides protection against virulent virus challenge.

Antioxidant Enzyme Activity and Meat Quality of Meat Type Ducks Fed with Dried Oregano (Origanum vulgare L.) Powder.

One-day-old Cherry valley meat-strain ducks were used to investigate the effect of supplemental dried oregano powder (DOP) in feed on the productivity, antioxidant enzyme activity, and breast meat quality. One hundred sixty five ducks were assigned to 5 dietary treatments for 42 days. The dietary treatment groups were control group (CON; no antibiotic, no DOP), antibiotic group (ANT; CON+0.1% Patrol), 0.1% DOP (CON+0.1% DOP), 0.5% DOP (CON+0.5% DOP), and 1.0% DOP (CON+1.0% DOP). Upon feeding, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity of oregano extracts was higher than that of tocopherol, although it was less than that of ascorbic acid. As a result of in vivo study, DOP in the diet showed no effects on final body weight, feed intake, or feed conversion ratio. However, dietary 0.5% and 1% DOP supplementation caused a significant increase in the serum enzyme activity of superoxide dismutase (SOD) compared with CON and ANT, while glutathione peroxidase (GPx) in tissue was increased as compared to ANT (p<0.05). Cooking loss from ducks fed with DOP decreased compared with the control ducks. Thiobarbituric acid reactive substance (TBARS) values of duck breast meat at 5 d post slaughter was found to be significantly reduced in ducks whose diets were supplemented with 0.5% and 1% DOP (p<0.05). These results suggest that diets containing 0.5% and 1% DOP may beneficially affect antioxidant enzyme activity of GPx and SOD, improve meat cooking loss, and reduce TBARS values in breast meat at 5 d of storage in ducks.

The duck genome and transcriptome provide insight into an avian influenza virus reservoir species

The duck (Anas platyrhynchos) is one of the principal natural hosts of influenza A viruses. We present the duck genome sequence and perform deep transcriptome analyses to investigate immune-related genes. Our data indicate that the duck possesses a contractive immune gene repertoire, as in chicken and zebra finch, and this repertoire has been shaped through lineage-specific duplications. We identify genes that are responsive to influenza A viruses using the lung transcriptomes of control ducks and ones that were infected with either a highly pathogenic (A/duck/Hubei/49/05) or a weakly pathogenic (A/goose/Hubei/65/05) H5N1 virus. Further, we show how the duck’s defense mechanisms against influenza infection have been optimized through the diversification of its β-defensin and butyrophilin-like repertoires. These analyses, in combination with the genomic and transcriptomic data, provide a resource for characterizing the interaction between host and influenza viruses.

Structural Adaptations Associated with Osmotic Stress of the Salt Gland in Birds

Introduction:When the drinking water of many species of ducks is changedfrom freshwater to saline, their salt glands hypertrophy and the principal cells showed numerous lateral cell evaginations and abundant mitochondria, enhancingtheir capacity to excrete salt. Aim of the work:The purpose of this investigation was to demonstrate and evaluate the anatomical, histological, and ultrastructural adaptations of the salt gland of the domestic female ducks associated with high salt osmotic stress. Material and methods: The present study was carried out on two groups of female domestic ducks and one group of wild ducks. Where as one group of domestic ducks was exposed to osmotic stress; imposed by replacing drinking tap water with 1% sodium chloride solution for two consecutive weeks. Morphometric measurements as well as histological and ultrastructural aspects of the salt glands were considered. Results: The investigation revealed that the weight and size of the salt glands of the salt-stressed ducks were markedly heavier and larger in comparison to those of the control and wild ducks. The number and the diameter of secretory lobules as well as the length of secretory tubules of the salt-stressed group were greater compared to the control ones.The degree of the proliferation and differentiation of the peripheral cells was distinctly greater for the salt-stressed than the control and wild ducks. The basal and lateral surfaces of the fully specialized secretory cell type in the salt-stressed and wild birds were obviously amplified and in many cases the folds of adjacent cells meshed with one another forming an elaborate complex of extracellular spaces and intracellular compartments. The cytoplasm of the fully specialized principal cells displayed abundant endoplasmic reticulum, numerous well developed mitochondria and deeply well developed basal foldings which increase the absorptive surface. Conclusion: The recorded peculiar features of the salt glands of the salt-stressed birds may be presented as an adaptive features to satisfy its special demands to eliminate the remarkable increased levels of sodium chloride load effectively.

The Functional Alterations of the Avian Salt Gland Subsequent to Osmotic Stress

Background: Many terrestrial non-marine birds have functional salt glands. Their salt glands are usually quiescent. However, such glands show remarkable levels of phenotypic plasticity both morphological and physiological as a consequence of drinking saline water. Objective: The current investigation was conducted to reveal in more detail the different functional alterations of the duck`s salt glands subsequent to high salt osmotic stress. Material and methods: The selected avian species were the domestic female (Anas platyrhyncha)and the wild migratory (Anas clypeata ) ducks. Two groups of domestic and one group of wild ducks were considered in the present study , each of which included nine adult ducks. The high salt osmotic stress was induced by replacing drinking tap water of the domestic ducks with 1% sodium chloride solution for two consecutive weeks. The measured parameters were included some electrolytes in both serum and glandular tissue. Also, Na-K-ATPase activity and aldosterone concentrations were considered. Results: The present study elucidated that serum sodium, potassium, chloride and uric acid of the wild migratory ducks were markedly higher than those of both salt-stressed and control ducks. In addition, serum aldosterone concentration of the wild migratory ducks was distinctly higher in comparison with those of the control and the salt-stressed ones. Moreover, salt gland tissue homogenate electrolyte contents followed the same pattern as those of serum electrolyte concentrations. In contrast, the activity of Na-K-ATPase of the salt gland homogenates was higher in the salt-stressed ducks in comparison to both wild migratory and control groups. Conclusion: From the above mentioned results, it was concluded that the peculiar functional status of the salt gland of the experimentally salt-stressed ducks comparing to the control may be presented as an adaptive features to satisfy its special demands to eliminate the remarkable increased levels of sodium chloride load effectively.

Conditioned response to a magnetic anomaly in the Pekin duck (Anas platyrhynchos domestica) involves the trigeminal nerve

There have been recent calls to develop protocols that collect unambiguous measures of behaviour using automatic techniques in conditioning experiments on magnetic orientation. Here, we describe an automated technique for recording the behaviour of Pekin ducks in a conditioning test that allows them to express unrestricted searching behaviour. Pekin ducks were trained to find hidden food in one corner of a square arena below which was placed a magnetic coil that produced a local magnetic anomaly. The trigeminal nerve was anaesthetised by injection of lignocaine hydrochloride 2-3 mm caudal to the medial canthus of each eye, medial to the globe, prior to the presentation of unrewarded tests. Lignocaine-treated ducks showed no initial preference for the magnetic anomaly whereas saline-treated control ducks showed a significant preference at the same age. A second experiment was undertaken in which the trigeminal nerve was surgically severed and 2-3 mm removed, and this surgery abolished the previously observed preference for the corner with the magnetic coil in a small number of ducks. These data show that Pekin ducks are able to detect and use magnetic stimuli to guide unrestricted search behaviour and are consistent with a hypothesis of magnetoreception involving a putative cluster of magnetite in the upper beak.

Deactivation of T-2 toxin in broiler ducks by biotransformation

SUMMARY Effects of 2 dietary levels (0.6 and 1.0 ppm) of T-2 toxin, and the possible protective capacity of a mycotoxin-inactivating feed additive (Detoxa Plus) were investigated in growing White Pekin ducklings in a 49-d trial comprising 6 treatment groups of 10 ducks/group. The experimental design consisted of 1 negative and 1 positive control and 4 test groups, as follows: group 1, negative control (no T-2 toxin and no feed additive added to the feeds); group 2, positive control (no T-2 toxin added, but the feeds were supplemented with feed additive at 2 kg/t); group 3, feeds were complemented with 0.6 ppm of purified T-2 toxin (no feed additive added); group 4, feeds were complemented with 0.6 ppm of T-2 toxin and 2 kg/t of the feed additive was provided; group 5, feeds were complemented with 1.0 ppm of T-2 toxin (no feed additive added); group 6, feeds were complemented with 1.0 ppm of T-2 toxin and 2 kg/t of the feed additive was provided. From wk 4 until the end of the trial, the daily BW gain of group 3 ducks was inferior to that of control ducks, and the differences in means were statistically significant (P ≤ 0.05) at wk 4 and 7. The final BW of this group was also significantly lower than that of the control (P ≤ 0.001). The BW gain of ducks in group 5 was also depressed by the toxin treatment. The adverse effect of 0.6 ppm of T-2 toxin was fully counteracted by the feed additive in terms of daily BW gain, cumulative daily BW gain, and BW at exsanguination. The T-2 toxin at both treatment levels depressed the blastogenic response of lymphocytes to nonspecific mitogens (concanavalin A and phytohaemagglutinin), which was counteracted by the feed additive at the lower dietary concentration of T-2 toxin. No such effect was observed with 1.0 ppm of T-2 toxin. Metabolic blood parameters and hematological data showed no consistent treatment effects. We conclude that this feed additive is able to counteract the adverse effects of T-2 toxin at dietary concentrations that might be encountered under field conditions.

Effects of dietary conjugated linoleic acid on the growth performance of chickens and ducks for fattening and fatty acid composition of breast meat

The effects of dietary conjugated linoleic acid (CLA) supplementation on feed intake, growth performance, carcass composition and fatty acid composition of meat tissue were investigated in broiler chickens and Pekin ducks. A total of 108 male chickens for fattening and a total of 96 male and 96 female Pekin ducks were allocated to 3 dietary treatments (0.0, 0.1 and 0.2 % CLA) and fed for 35 or 49 days. The results showed that 0.2 % CLA supplementation in the first 3 weeks improved the daily feed intake of the broilers and the feed to gain ratio, but did not significantly influence body weight, weight and the percentage of abdominal and visceral fat as well as the intramuscular fat in breast muscles. In the duck trial, the daily feed intake was significantly higher through the first 3 weeks of male control group and male 2 g CLA group compared with the female control group. The daily weight gain of all male ducks was significantly higher compared to female ducks of all groups and was not influenced by the CLA supplementation. The feed to gain ratio of the 1 g CLA-male ducks was lowest compared to male and female control ducks and 1 and 2 g CLA female ducks. Supplementing diets with CLA modified the fatty acid composition of breast muscle. The proportion of CLA was increased in broiler meat. In duck meat, the proportions of CLA, saturated fatty acids and polyunsaturated fatty acids were increased and monounsaturated fatty acids were decreased.

Effects of perilla extract on productive performance, serum values and hepatic expression of lipid-related genes in Shaoxing ducks

1. The aim of this study was to identify the effect of perilla extract, a source of polyunsaturated fatty acids, on lipid metabolism and expression of lipid-related genes in livers of Shaoxing ducks. 2. Two hundred and forty 28-week-old laying ducks received a commercial diet with perilla extract added at 0 (control) or 200 mg/kg of feed. 3. Ducks fed on a diet with perilla extract had increased laying rates compared with control ducks. 4. Serum concentrations of triglycerides were reduced by perilla extract, while high-density lipoprotein cholesterol and total serum cholesterol increased. 5. The expression of genes involved in hepatic lipogenesis, sterol regulatory element-binding protein-1, acetyl CoA carboxylase, stearoyl CoA desaturase, fatty acid synthase, apolipoprotein B, and apolipoprotein very low density lipoprotein, were decreased in the perilla group. 6. The mRNA expression of peroxisome proliferators-activated receptor alpha and acyl-coenzyme A oxidase was enhanced following treatment with perilla extract, and a similar tendency was observed in the expression of liver fatty acid-binding protein. 7. The results show that a diet with 200 mg/kg perilla extract regulated fat metabolism of Shaoxing ducks by improving egg laying, altering serum lipid profiles, stimulating lipid catabolic gene expression and inibiting lipogenic gene expression in the liver.

The development of persistent duck hepatitis B virus infection can be prevented using antiviral therapy combined with DNA or recombinant fowlpoxvirus vaccines

We recently reported the development of a successful post-exposure combination antiviral and “prime-boost” vaccination strategy using the duck hepatitis B virus (DHBV) model of human hepatitis B virus infection. The current study aimed to simplify the vaccination strategy and to test the post-exposure efficacy of combination therapy with the Bristol-Myers Squibb antiviral drug, entecavir (ETV) and either a single dose of DHBV DNA vaccines on day 0 post-infection (p.i.) or a single dose of recombinant fowlpoxvirus (rFPV–DHBV) vaccines on day 7 p.i. Whilst untreated control ducks infected with an equal dose of DHBV all developed persistent and wide spread DHBV infection of the liver, ducks treated with ETV combined with either the DHBV DNA vaccines on day 0 p.i. or the rFPV–DHBV vaccines on day 7 p.i. had no detectable DHBV-infected hepatocytes by day 14 p.i. and were protected from the development of persistent DHBV infection.

The persistence in the liver of residual duck hepatitis B virus covalently closed circular DNA is not dependent upon new viral DNA synthesis

Residual hepatitis B virus (HBV) DNA can be detected following the resolution of acute HBV infection. Our previous work using duck hepatitis B virus (DHBV) infected ducks, indicated that ~ 80% of residual DHBV DNA in the liver is in the covalently closed circular DNA (cccDNA) form, suggesting that viral DNA synthesis is suppressed. The current study asked more directly if maintenance of residual DHBV cccDNA is dependent upon ongoing viral DNA synthesis. Ducks that recovered from acute DHBV infection were divided into 2 groups and treated with the antiviral drug, Entecavir (ETV), or placebo. No major differences in the stability of cccDNA or levels of residual cccDNA were observed in liver biopsy tissues taken 95 days apart from ETV treated and placebo control ducks. The data suggest that residual DHBV cccDNA is highly stable and present in a cell population with a rate of turnover similar to normal, uninfected hepatocytes.

Propagation of vaccine strain of duck enteritis virus in a cell line of duck origin as an alternative production system to propagation in embryonated egg

Duck virus enteritis (DVE) also known as duck plague, is a viral infection of ducks caused by duck enteritis virus (DEV). The control of the disease is mainly done by vaccination with a chicken embryo-adapted live virus that is known to be poorly immunogenic and affords partial protection. Further, the risk of harboring other infectious agents in the embryo particularly the deadly and zoonotic avian influenza virus is also high. In this paper, we report propagation of a chicken embryo-adapted vaccine strain of duck enteritis virus in duck embryo fibroblast (DEF) cell line. Thirty serial passages were done in DEF cell that made the vaccine virus further attenuated which was tested in ducks. The growth behaviors of the virus in DEF cells were studied and at 30th passage level the virus titre was found to be 10 6.8 TCID 50/ml. Ducks were immunized with this virus and challenged after 21 days with high dose of virulent DEV. All the immunized ducks withstood challenge with no clinical symptoms in any of the ducks while all the control ducks died. DEF cell which is free from other infectious agents appears to be a good system for cultivation of duck enteritis virus vaccine strain.

Effect of dietary cadmium on lipid metabolism and storage of aquatic bird Cairina moschata

In environment, birds often fast in connection with breeding, migration or drastic climatic conditions and need to mobilize lipid reserves during these periods. The impairment of lipid metabolism by cadmium (Cd; 1 mg kg(-1) added in diet) was investigated on palmiped Cairina moschata. Expression levels of genes involved in lipid metabolism, mitochondrial metabolism and detoxification were investigated in liver and muscle of ducks. Lipid content in muscle and liver were analysed and plasma triglycerides were quantified. After 20 days, ducks exposed to Cd displayed a lower body weight and lower lipid content in liver than controls. In muscle, the increase of lipid content was only significant for control ducks but not for exposed ducks. Exposed ducks appeared unable to sufficiently transport and store lipids into peripheral tissues. Cd impairs lipid metabolism by several ways. First, Cd triggered the down-regulation of fatty acids synthesis in liver even if the NADPH production and the mitochondrial metabolism are enhanced, suggesting a stronger energy needs. Secondly, the associated decrease of plasma triglycerides and lipoprotein lipase activity with Cd are consistent with impairment of lipids storage in peripheral tissues.

Vaccination of ducks with a whole-cell vaccine expressing duck hepatitis B virus core antigen elicits antiviral immune responses that enable rapid resolution of de novo infection

As a first step in developing immuno-therapeutic vaccines for patients with chronic hepatitis B virus infection, we examined the ability of a whole-cell vaccine, expressing the duck hepatitis B virus (DHBV) core antigen (DHBcAg), to target infected cells leading to the resolution of de novo DHBV infections. Three separate experiments were performed. In each experiment, ducks were vaccinated at 7 and 14 days of age with primary duck embryonic fibroblasts (PDEF) that had been transfected 48 h earlier with plasmid DNA expressing DHBcAg with and without the addition of anti-DHBcAg (anti-DHBc) antibodies. Control ducks were injected with either 0.7% NaCl or non-transfected PDEF. The ducks were then challenged at 18 days of age by intravenous inoculation with DHBV (5 × 10 8 viral genome equivalents). Liver biopsies obtained on day 4 post-challenge demonstrated that vaccination did not prevent infection of the liver as similar numbers of infected hepatocytes were detected in all vaccinated and control ducks. However, analysis of liver tissue obtained 9 or more days post-challenge revealed that 9 out of 11 of the PDEF-DHBcAg vaccinated ducks and 8 out of 11 ducks vaccinated with PDEF-DHBcAg plus anti-DHBc antibodies had rapidly resolved the DHBV infection with clearance of infected cells. In contrast, 10 out of 11 of the control unvaccinated ducks developed chronic DHBV infection. In conclusion, vaccination of ducks with a whole-cell PDEF vaccine expressing DHBcAg elicited immune responses that induced a rapid resolution of DHBV infection. The results establish that chronic infection can be prevented via the vaccine-mediated induction of a core-antigen-specific immune response.