Live Newcastle Disease Research Articles

Enhanced pathogenicity of low-pathogenic H9N2 avian influenza virus after vaccination with infectious bronchitis live attenuated vaccine.

Aim:In the present study, two experiments were carried out for studying the pathogenicity of H9N2 avian influenza virus (AIV) in broiler chickens after vaccination with different live respiratory viral vaccines.Materials and Methods:One-day-old specific pathogen-free (SPF) chicks were divided into four groups in each experiment. In experiment 1, Groups 1 and 2 were inoculated with H9N2 AIV through nasal route in 1 day old, Groups 1 and 3 were vaccinated with live infectious bronchitis coronavirus (IBV) vaccine in 5 days old, and Group 4 was left as a negative control. In experiment 2, Groups 5 and 6 were inoculated with AIV subtype H9N2 through nasal route in 1 day old, Group 5 was vaccinated with live IBV vaccine and live Newcastle disease virus (NDV) vaccine in 5 and 18 days old, respectively, Groups 6 and 7 were vaccinated with live NDV vaccine in 18 days old, and Group 8 was left as a negative control. Chicks were kept in isolators for 18 days in the first experiment and 35 days in the second experiment. Tracheal and cloacal swabs were collected from 3, 5, 7, 10, 12, and 15 day’s old chicks from all groups in experiment 1 and 21, 23, 25, and 28 days old from all groups in experiment 2. Quantitative real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) was applied on the collected tracheal swabs for detecting RNA copies of H9N2 AIV. Cloacal swabs and the positive rRT-PCR tracheal swabs were inoculated in 10-day-old SPF embryonated chicken eggs (ECE) to confirm rRT-PCR results. Internal organs (kidney, trachea, and spleen) from all chicken groups were collected weekly for histopathological examination to determine severity of the lesions. Serum samples were collected on a weekly basis for the detection of humoral immune response against H9N2, NDV, and IBV from all chicken groups.Results:rRT-PCR results with virus titration in ECEs revealed a significant increase in H9N2 AIV titer with extension in the period of viral shedding in Groups 1 and 5. Severe lesion score was observed for Groups 1 and 5. The humoral immune response against H9N2 AIV, NDV, and IBV revealed a significant increase in H9N2 AIV titer in Groups 1 and 5, NDV titer showed a significant increase in Group 7, and IBV titer increased in Groups 1, 3, and 5.Conclusion:Results demonstrated the increase in pathogenicity of H9N2 AIV, especially when H9N2-infected chicks vaccinated with live IBV vaccine.

Response of live Newcastle disease virus encapsulated in N-2-hydroxypropyl dimethylethyl ammonium chloride chitosan nanoparticles

We have synthesized N-2-hydroxypropyl dimethylethyl ammonium chloride chitosan (N-2-HFCC) with higher water solubility than chitosan. To evaluate its potential as delivery carrier, NDV encapsulated in N-2-HFCC/CMC nanoparticles (NDV/La Sota-N-2-HFCC/CMC-NPs) with a diameter of 252.2±32.68nm, Zeta potential of 41.1±0.89mV, encapsulation efficiency of 96.6±0.72% and loading capacity of 53.2±1.11% were prepared. NDV/La Sota-N-2-HFCC/CMC-NPs are a novel type of attenuated live vaccine encapsulated in nanoparticles. These nanoparticles displayed lower cytotoxicity and higher stability. Their bioactivity was maintained when they were stored for three months at the room temperature. Release assay in vitro showed that NDV could be sustainably released after an initial burst release. In vivo immunization showed that immunization of specific pathogen free chickens with NDV/La Sota-N-2-HFCC/CMC-NPs intranasally induced high titers of serum antibody, significantly promoted lymphocyte proliferation and caused higher levels of interleukine-2 and interference-γ. These results indicated that N-2-HFCC/CMC nanoparticles could serve as an efficient and safe delivery vehicle for mucosal immunity, and have a great potential in medical applications.

Isolation, identification, and hexon gene characterization of fowl adenoviruses from a contaminated live Newcastle disease virus vaccine

To investigate the possible causes of the massive spread of fowl adenovirus (FAdV) infection among chickens in recent years in China, 32 batches of live-virus vaccines were tested for contamination with FAdV by PCR. Among these, 1 live Newcastle disease virus (NDV) vaccine of the LaSota strain was demonstrated to be positive for contamination. The amplified hexon gene exhibited 99.8% identity with a recent Chinese field isolate (JSJ13) of FAdV-4. The positive LaSota vaccine was first neutralized with anti-NDV serum and then inoculated into specific pathogen-free embryos at embryonic day 5 through the yolk sac for isolation of the contaminated FAdV. The same hexon gene bands were amplified from extracted DNA of the liver tissues and chicken embryo allantoic fluid of the inoculated embryos, indicating the replication and isolation of the FAdV-4 virus strain that had contaminated the vaccine. This represents the first report of FAdV-4 contamination in a live vaccine for poultry in China. These findings suggest that contamination of live vaccine might represent one of the most important causes of massive outbreaks of FAdV infection among chickens and indicate that FAdV should therefore be included in the regular monitoring list for the detection of exogenous viral contamination of attenuated vaccines for poultry.

Biological evaluation of N-2-hydroxypropyl trimethyl ammonium chloride chitosan as a carrier for the delivery of live Newcastle disease vaccine

Mucosal immune system plays a very important role in antiviral immune response. We prepared Newcastle disease viruses (NDV) encapsulated in N-2-hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) nanoparticles (NDV/La Sota-N-2-HACC-NPs) by an ionic cross linking method, and assessed the potential of N-2-HACC-NPs as a mucosal immune delivery carrier. The properties of the nanoparticles were determined by transmission electron microscopy, Zeta potential and particle size analysis, encapsulation efficiency and loading capacity. NDV/La Sota-N-2-HACC-NPs have regular spherical morphologies and high stability; with 303.88±49.8nm mean diameter, 45.77±0.75mV Zeta potential, 94.26±0.42% encapsulation efficiency and 54.06±0.21% loading capacity. In vitro release assay indicated that the release of NDV from NDV/La Sota-N-2-HACC-NPs is slow. The NDV/La Sota-N-2-HACC-NPs have good biological characteristics, very low toxicity and high level of safety. Additionally, specific pathogen-free chickens immunized with NDV/La Sota-N-2-HACC-NPs showed much stronger cellular, humoral and mucosal immune responses than commercial attenuated live Newcastle disease vaccine, and NDV/La Sota-N-2-HACC-NPs reached the sustainable release effect. Our study here provides a foundation for the further development of mucosal vaccines and drugs, and the N-2-HACC-NPs should be a potential drug delivery carrier with immense potential in medical applications.

Prophylactic potential of resiquimod against very virulent infectious bursal disease virus (vvIBDV) challenge in the chicken

The study evaluated the prophylactic potential of resiquimod (R-848), a synthetic TLR7 agonist, against very virulent infectious bursal disease virus (vvIBDV) infection in chicken. Specific pathogen free White Leghorn chicks of three week age were treated with R-848 (50μg/bird, intramuscular) or PBS (n=26/group). Twenty four hour later, half of the birds from each group were challenged with 105 ELD50 of vvIBDV and observed for 10days. To understand the effect of R-848, immune response genes such as interferon (IFN)-β, IFN-γ, IL-1β, IL-4, iNOS and TLR7 were analyzed at 24 and 48h post-challenge in PBMCs ex vivo by real-time PCR (n=6/group). On day 4 post-challenge, representative birds (n=3/group) were sacrificed to study the bursal damage and IBDV antigen clearance. Immunosuppression was assessed by antibody response against live Newcastle disease virus (NDV) vaccine, which was administered on day 10 post-challenge. R-848 pre-treatment significantly upregulated the transcripts of each immune response gene studied (P<0.05). There was 50% mortality on vvIBDV challenge in control birds, while it was only 20% with R-848 group. R-848 pre-treatment reduced the bursal damage as indicated by lower bursal lesion score in histopathology, reduced IBDV antigen signal in immunohistochemistry and improved antigen clearance in agar gel immunodiffusion test. Further, it protected significantly against vvIBDV induced immunosuppression as indicated by HI antibody titre. It is concluded that pre-treatment of R-848 conferred partial protection from mortality and bursal damage while complete protection against immunosuppression in chicken when challenged with vvIBDV, which could be due to the upregulation of immune response genes.

O-2′-Hydroxypropyltrimethyl ammonium chloride chitosan nanoparticles for the delivery of live Newcastle disease vaccine

A novel complex chitosan derivative, O-2′-hydroxypropyltrimethyl ammonium chloride chitosan (O-2′-HACC), was synthesized and used to make nanoparticles as a delivery vehicle for live attenuated Newcastle disease vaccine. We found that O-2′-HACC had high antimicrobial activity, low toxicity, and a high safety level. Newcastle disease virus (NDV) was then encapsulated in the O-2′-HACC nanoparticles (NDV/La Sota-O-2′-HACC-NPs) by the ionic crosslinking method, and the properties of the resulting nanoparticles were determined by transmission electron microscopy, Zeta potential analysis, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction. NDV/La Sota-O-2′-HACC-NPs had regular spherical morphologies and high stability, with an encapsulation efficiency of 95.68±2.2% and a loading capacity of 58.75±4.03%. An in vitro release assay indicated that release of NDV from NDV/La Sota-O-2′-HACC-NPs occurred slowly. Specific pathogen-free chickens immunized with NDV/La Sota-O-2′-HACC-NPs intranasally had much stronger cellular, humoral and mucosal immune responses than did those immunized intramuscularly or with live attenuated Newcastle disease vaccine. NDV/La Sota-O-2′-HACC-NPs are a novel drug delivery carrier with immense potential in medical applications.

Immune responses and interactions following simultaneous application of live Newcastle disease, infectious bronchitis and avian metapneumovirus vaccines in specific-pathogen-free chicks

Interactions between live Newcastle disease virus (NDV), avian metapneumovirus (aMPV) and infectious bronchitis virus (IBV) vaccines following simultaneous vaccination of day old specific pathogen free (SPF) chicks were evaluated. The chicks were divided into eight groups: seven vaccinated against NDV, aMPV and IBV (single, dual or triple) and one unvaccinated as control. Haemagglutination inhibition (HI) NDV antibody titres were similar across all groups but were above protective titres. aMPV vaccine when given with other live vaccines suppressed levels of aMPV enzyme-linked immunosorbent assay (ELISA) antibodies. Cellular and local immunity induced by administration of NDV, aMPV or IBV vaccines (individually or together) showed significant increase in CD4+, CD8+ and IgA bearing B-cells in the trachea compared to the unvaccinated group. Differences between the vaccinated groups were insignificant. Simultaneous vaccination with live NDV, aMPV and IBV did not affect the protection conferred against aMPV or IBV.

Isolation, identification, and gp85 characterization of a subgroup A avian leukosis virus from a contaminated live Newcastle Disease virus vaccine, first report in China

To identify if any exogenous avian leukosis virus (ALV) exists in a live vaccine of poultry according to the directives of the Ministry of Agriculture of the People's Republic of China, a live vaccine strain of the Newcastle disease virus (NDV) was neutralized using an anti-NDV antibody, and was subsequently used to inoculate DF-1 cells to investigate the presence of exogenous ALV. The DF-1 cells were cultured for 21 d and subsequently screened using an ELISA for the p27 antigen of the ALV. An exogenous ALV, designated ALV-NDVP4, was identified. The nucleotide sequence of the gp85 gene of the ALV-NDVP4 was compared with those of the various subgroups of the ALV. The amino acid sequence identities for the predicted gp85 of the ALV-NDVP4 and those of the ALV reference strains ranged from 88.2 to 99.5% for the 12 of the subgroup A strains of ALV (ALV-A) and from 82.7 to 87.4% for the B, C, D, and E subgroup strains. The amino acid sequence identities for the gp85 of the ALV-NDVP4 and those of the subgroup J reference strains ranged from 48.7 to 49.9%. The ALV-NDVP4 shared the highest level of homology with the SDAU09C3 strain of ALV-A, which was isolated in China, suggesting a common origin. This is the first report of ALV-A contamination in a live vaccine for poultry in China. Our findings highlight the need for improved monitoring methods for poultry vaccine production.

Consequence of Cryptosporidiosis on the immune response of vaccinated broiler chickens against Newcastle disease and/or avian influenza.

The consequence of cryptosporidiosis on the immune response of vaccinated chickens against Newcastle disease and/or avian influenza was studied by using 240, 1 day old, male, white Hy-Line chicks and divided into 8 groups and subgroups. Each group or subgroup was consisting of 30 chicks (15 × 2 replicates). The first and second groups were kept as unvaccinated control, G1uninfected and G2 infected. G3, G4 and G5 contained 2 subgroups A&B (G3A, G3B, G4A, G4B, G5A and G5B). Chicks of subgroup A were vaccinated only while chicks of subgroup B were infected and vaccinated. These chicks were orally inoculated with 5 × 10(5) oocysts of Cryptosporidium baileyi (C. baileyi) at 2 days of age. Chickens were vaccinated intraocular with live Newcastle disease (ND) vaccine (Hitchner on day 7th and LaSota on day 17th of chicken life) (G3) or vaccinated by subcutaneous route with Volvac®- H5N2- AI vaccine on day 10 of chicken life (G4). Last group (G5) was infected similarly and vaccinated with ND and AI vaccines with the same day, dose and route of vaccination for each one. Random blood samples were collected for 3 weeks post-vaccination for investigation of humoral immune response against Newcastle and/or avian influenza vaccines by the haemagglutination inhibition (HI) test. The results showed that H5N2 vaccine at day 10 of chicken life is effective in chickens indicated by the geometric mean of HI titer against AI virus. The findings of this study showed that the infection with Cryptosporidia in the broiler chicken has a depressive effect on the immune status of the birds vaccinated against ND and/or AI vaccination. Moreover, the obtained protection rates against challenge with virulent ND virus observed to be parallel to the results of HI- test. Also, by using 2 different antigens (one commercial and field prepared antigen) to avian influenza virus, lower Geometric mean (GM) HI titer were appeared in infected and vaccinated group than vaccinated group only. A study of the relative lymphoid organs weight such as bursa of Fabricius from the experimental chicks indicated that those organs were comparable between the groups infected-vaccinated and vaccinated only. Non significant variations in final live weight between uninfected control and infected groups were indicated. Also, H5N2-AI vaccination at 10 days old did not affect the final live weight. ND and/or AI Vaccination could not be a substitute to application of good hygienic measures and fecal examination of the birds especially for protozoal diseases such as cryptosporidiosis. It could be concluded that cryptosporidiosis could be one cause of ND and/or AI vaccination failure in poultry farms.

Analysis of Chicken T Cell-Mediated Responses on Thymus after Immune Stress

In order to assess chicken T cell-mediated responses after immune stress, 200 two-week-old chickens were randomly divided into control group(C) and treatment groups (T1 and T2). The live I-type of Newcastle disease vaccine (ND) was taken as the source of immunological stress. The chickens in group (T2) were injected with overdose of live I-type Newcastle disease vaccine. After vaccination, the dynamic changes of CD4+, CD8+T cells on thymus were detected by immunohisto-chemistry. The ultra-structure of T cells on thymus of the chickens in group (T2) was observed by electron microscopic. The result showed: (1) After immune stress, from day 1 to day 5, the number of the CD4+T cells significantly declined and reached the bottom at day 5, but the number of the CD8+T cells increased dramatically and peaked at day 5. (2) After immune stress, from day 1 to day 5, part of T cells of chicken thymus came with apoptotic and pathological changes of putrescence continually. These results underscore: the immune stress can cause transient immune adjustment. These changes for chickens were the self-protection mechanism of immune system to adapt to survival and avoid immune disorder.

Effect of Zataria multiflora essential oil on immune responses and faecal virus shedding period in broilers immunized with live Newcastle disease vaccines

Summary Zataria multiflora essential oil possesses immunomodulatory effects and the present study investigates its effect on immune responses to live Newcastle disease (ND) vaccines and faecal shedding period of vaccine strain virus in chickens. One hundred and eighty chickens from both sexes were divided into 6 equal groups: group 1: unvaccinated, group 2: vaccinated (B1 vaccine followed by La Sota 10 days later), group 3: vaccinated + levamisole (150 mg/kg/day, orally), groups 4, 5 and 6 were vaccinated and received Z. multiflora essential oil by SC injections at 0.1, 0.2 and 0.4 g/kg/day dosages, respectively. Levamisole and Z. multiflora essential oil were administered for 10 and 5 consecutive days post B1 vaccination. On days 0, 7, 14, 28 and 35 post booster vaccination (PBV), HI test was performed. Delayed type hypersensitivity (DTH) test was accomplished on day 14 PBV. Faecal virus shedding was determined during 15 days PBV with 3 day intervals by RT-PCR method. Zataria multiflora essential oil induced a dose-dependent increase in antibody titers in an extent higher than levamisole as well as a dose-dependent suppression of DTH reaction. Effect of Z. multiflora essential oil at the dosage of 0.1 g/kg on shortening of faecal virus shedding period was exactly the same as levamisole where higher doses demonstrated stronger decrease. In conclusion, Z. multiflora essential oil stimulates humoral immune responses and shortens faecal virus shedding period while suppressing cell-mediated immune responses in chickens vaccinated with live ND vaccines.

Effect of the Commercial Mixed Live Newcastle Disease and Infectious Bronchitis Vaccines and the Use of Two Separate Vaccines Given Simultaneously on Systemic Antibody Responses

Background and Aims: The objective of this study was to investigate the effects of Newcastle Disease and Infectious Bronchitis vaccination programs in chickens. Materials and Methods and Results: In the present study, 225 day-old broiler chicks divided into 5 groups. The groups were submitted to vaccinations, except for the nonvaccinated control group. The chickens in the groups 1 were kept as a control group and did not receive vaccine. The chickens in the group 2 were vaccinated with commercial mixed vaccine. The chickens in the groups 3 were vaccinated with two separate vaccines simultaneously. The chickens in the group 4 were vaccinated with single ND vaccine. The chickens in the groups 5 were vaccinated with single IB vaccine. Sera were collected at 18 and 45 days of age and submitted to serologic tests to assess antibody levels. Conclusion: Results demonstrate that there is not any significant statistical difference between the vaccinated groups.

Effect of garlic and neem leaf aqueous extracts on immune response of broilers to live Newcastle disease vaccine

This study was designed to determine the effects of Garlic and Neem leaf aqueous extracts on their individual basis and/ or mixture on humoral immune response of broilers against NDV (Newcastle Disease Virus) Vaccine. One hundred and sixty day old broiler chicks were randomly allocated into four groups A, B, C and D. All the birds were raised in individual cages beneath the same house operating under conventional deep litter system. Group A was regarded as control received neither of the extracts. Group B, C and D were treated with 5g Garlic, 5g Neem leaf and a mixture of 2.5g Garlic and 2.5g Neem leaf extracts respectively mixed per liter of drinking water for the first 3 weeks and the experimental birds lasted for 8 weeks. The birds from all the groups were vaccinated with ND- La Sota vaccine orally at 21 day old. Ten blood samples were taken from each group on day 1, 7, 14 and 21 after the vaccination. The serum antibody level against NDV was measured by HI test. Better immune response (p 0.05) between the treated groups. Present findings suggest that aqueous extracts of garlic and neem leaf enhanced the immunomodulatory response to live ND vaccine.

Preparation and Optimization of a Live Newcastle Disease Virus Vaccine Encapsulated in Chitosan Nanoparticles

In this study, the researcher’s interest is focused on establishing a model with La Sota live vaccine immobilized into chitosan, which was prepared using a ionic gelation method. The formulation, preparation procedure, influence factors, physicochemical characteristics were evaluated. The results of study demonstrate that the NDV-CS-NPs have been produced with suitable size, morphous regulation, extremely spherical shape, regular and well-distributed. The NDV-CS-NPs produced by the optimal formulation were average size (371.1nm) and proper zata potential (+2.84 mV). The entrapment efficiency was (74±3.7) %. It can provide a new useful information for the development and evaluation of synthetic vaccines.

Preparation and Efficacy of a Live Newcastle Disease Virus Vaccine Encapsulated in Chitosan Nanoparticles

BackgroundNewcastle disease (ND) is a highly contagious viral disease of poultry caused by pathogenic strains of the Newcastle disease virus (NDV). Live NDV vaccines are administered by drinking water, eyedrops or coarse aerosol spray. To further enhance mucosal immune responses, chitosan nanoparticles were developed for the mucosal delivery of a live NDV vaccine.Methodology/Principal FindingsA lentogenic live-virus vaccine (strain LaSota) against NDV encapsulated in chitosan nanoparticles were developed using an ionic crosslinking method. Chitosan nanoparticles containing the lentogenic live-virus vaccine against NDV (NDV-CS-NPs) were produced with good morphology, high stability, a mean diameter of 371.1 nm, an encapsulation rate of 77% and a zeta potential of +2.84 mV. The Western blotting analysis showed that NDV structural proteins were detected in NDV-CS-NPs. The virus release assay results of NDV-CS-NPs indicated that NDV was released from NDV-CS-NPs. Chickens immunized orally or intranasally with NDV-CS-NPs were fully protected whereas one out of five chickens immunized with the LaSota live NDV vaccine and three out of five chickens immunized with the inactivated NDV vaccine were dead after challenge with the highly virulent NDV strain F48E9.Conclusions/SignificanceNDV-CS-NPs induced better protection of immunized specific pathogen free chickens compared to the live NDV vaccine strain LaSota and the inactivated NDV vaccine. This study lays a foundation for the further development of mucosal vaccines and drugs encapsulated in chitosan nanoparticles.

Characterization of avian paramyxovirus type 1 from migratory wild birds in chickens

Newcastle disease virus (NDV) is one of the most important infectious agents in the poultry industry, and vaccines against it have been widely used for prevention and control. Live vaccines, which can replicate in the respiratory and digestive systems, have been especially needed in areas with outbreaks of viscerotropic velogenic Newcastle disease. Towards the goal of searching for a new live vaccine candidate, avian paramyxovirus type 1 (APMV-1) was isolated from the faeces of wild birds. Three APMV-1 strains thus isolated were characterized in terms of phylogeny, pathogenicity, immunogenicity and tissue tropism, and on the basis of these analyses were classified as lentogenic genotype I NDV. CBU2179, one of the three APMV-1 strains, was selected and was evaluated in terms of its efficacy and safety in specific pathogen-free chickens and commercial broilers. The manufactured trial vaccine from this strain, also called CBU2179, induced similar immune responses to those of VG/GA and B1 commercial vaccines, and provided 100% protection against challenge from viscerotropic velogenic NDV, KJW/49 strain (the official challenge strain in Korea). Also, the CBU2179 virus was re-isolated and persisted as long as or longer than other vaccine strains in both the respiratory and alimentary tracts. Therefore, the CBU2179 strain may represent a good candidate for a live Newcastle disease vaccine to protect chickens against viscerotropic velogenic NDV.

Effect of oral administration of ginseng stem-and-leaf saponins (GSLS) on the immune responses to Newcastle disease vaccine in chickens

This study was designed to evaluate the effect of oral administration of ginseng stem-and-leaf saponin (GSLS) on immune responses in chickens vaccinated with live Newcastle disease (ND) vaccines. In experiment 1, chickens were orally administered GSLS (2.5, 5, 10, and 20mg/kg) in drinking water for 3 days, and then intranasally vaccinated with ND vaccine. Hemagglutination inhibition (HI) test showed that the optimal dose of GSLS for enhancing HI titers was 5mg/kg. In experiment 2, chickens were fed with GSLS (5mg/kg) for 7, 5 or 3 days before vaccination. Result indicated that GSLS enhanced HI titers in a time-dependent manner. The order of the duration for drinking GSLS on increasing HI titers was 7 days>5 days>3 days. In experiment 3, chickens were fed with GSLS before or after immunization. Serum was sampled at a week interval for 5 weeks for HI test, splenic lymphocytes were prepared at weeks 2 and 4 after the booster immunization for lymphocyte proliferation test (LPT) and intestinal tissues were sampled at week 4 after the booster immunization for immunohistochemistry and histological examination. Results showed that HI titer, LPT, IgA+ cells and intestinal intraepithelial lymphocytes (iIELs) were significantly higher in chickens drinking GSLS before vaccination than those after vaccination. Therefore, oral administration of GSLS in drinking water at a dose of 5mg/kg for 7 days significantly increased systemic as well as gut mucosal immunity in chickens immunized with ND vaccine. Considering the immune potentiating effect of GSLS on ND vaccine, GSLS should be evaluated for its oral adjuvant effect on the immune response against other diseases such avian influenza and infectious bursal disease.

Effect of industrial product IMBO® on immunosuppressed broilers vaccinated with Newcastle disease vaccine

The effect of IMBO was investigated on humoral immune response to Newcastle disease vaccines in broiler chickens. Haemagglutination inhibition test and enzyme-linked immunosorbent assay were used to assess the immune response. Results showed that although IMBO significantly enhanced humoral immune response to live Newcastle disease vaccine, it did not decrease post virulent NDV challenge mortality.

The positive adjuvant effect of chitosan on antigen-specific cell-mediated immunity after chickens vaccination with live Newcastle disease vaccine

The development of safe, novel strong adjuvants is necessary to maximize the efficacy of and the immune response induced by new and/or available vaccines administered through the mucosal route to chickens. Chitosan is a non-toxic, biocompatible, biodegradable and natural polysaccharide derived from the exoskeleton of crustaceans and insects. It has been demonstrated to be an effective absorption enhancer to improve mucosal delivery of peptide and protein drugs in human and mice. In poultry, mucosal administration of live vaccine has been already explored with success. However, the effects of the use of the chitosan as adjuvant for mucosal vaccination in birds have not been investigated yet. To this aim, we explored its potential as adjuvant given by oculo-nasal route to one-day-old chickens with live Newcastle disease (ND) vaccine. The immune response has been evaluated during three independent vaccination experiments on specific pathogen free (SPF) chickens. It was shown that chitosan enhanced the antigen-specific cell-mediated immune response in the spleen. New protocols were developed to measure the chicken IFNγ production after ex vivo antigen-stimulation of peripheral blood and duodenal lamina propria lymphocytes. It was then observed than the peripheral cellular immune response was earlier and stronger, while the local cellular immune response in digestive tract as shorter when chitosan was used as adjuvant. On the other hand, the chitosan had no effect on the systemic, lachrymal and digestive antibody-mediated immunity. This study indicates thus that the chitosan is a cell-promising adjuvant for the mucosal delivery of live vaccine in poultry, by enhancing the Th1 pathway of immunity. However, further investigations are required to explore its mechanism of action and to evaluate the inferred protection.

Humoral, cell-mediated and mucosal immunity induced by oculo-nasal vaccination of one-day-old SPF and conventional layer chicks with two different live Newcastle disease vaccines

To further characterize the immune response elicited by two live Newcastle disease vaccines, humoral, cellular and mucosal immunity was evaluated after oculo-nasal vaccination of day-old chickens. The preferential replication sites for each vaccine strain were investigated by screening different tissues using quantitative real-time reverse transcription-polymerase chain reaction (QRRT-PCR). The interference of maternally derived antibody with vaccination was also considered in conventional layer chickens. In SPF chickens, similar humoral immune-response was measured in blood and tears but a differential profile of cell-mediated immunity was observed according to the vaccine strain. The lung-associated humoral immunity was higher with the tracheotropic strain while the enterotropic vaccine induced a more important specific immunity in the digestive tract. The presence of maternally derived antibody in conventional layer chickens limited, if not completely abrogated, their immune responses to vaccination. This study increases our understanding of the protective immune response against Newcastle disease virus (NDV) and provides new useful informations for the development and evaluation of new types of vaccines.