Immunoglobulin class distribution of systemic and mucosal antibody responses to Newcastle disease in chickens

Protection of Chickens with Maternal Immunity Against Avian Influenza Virus (AIV) by Vaccination with a Novel Recombinant Newcastle Disease Virus Vector

Newcastle disease virus (NDV) vectors expressing avian influenza virus (AIV) hemagglutinin of subtype H5 protect specific pathogen-free chickens from Newcastle disease and avian influenza. However, maternal AIV antibodies (AIV-MDA+) are known to interfere with active immunization by influencing vaccine virus replication and gene expression, resulting in inefficient protection. To overcome this disadvantage, we inserted a transgene encoding a truncated soluble hemagglutinin (HA) in addition to the gene encoding membrane-bound HA from highly pathogenic avian influenza virus (HPAIV) H5N1 into lentogenic NDV Clone 30 genome (rNDVsolH5_H5) to overexpress H5 antigen. Vaccination of 3-wk-old AIV-MDA+ chickens with rNDVsolH5_H5 and subsequent challenge infection with HPAIV H5N1 3 wk later resulted in 100% protection. Vaccination of younger chickens with higher AIV-MDA levels 1 and 2 wk after hatch resulted in protection rates of 40% and 85%, respectively. However, all vaccinated chickens showed strongly reduced shedding of challenge virus compared with age-matched, nonvaccinated control chickens. All control chickens succumbed to the HPAIV infection with a grading in disease progression between the three groups, indicating the influence of AIV-MDAs even at a low level. Furthermore, the shedding and serologic data gathered after immunization indicate sufficient replication of the vaccine virus, which leads to the assumption that lower protection rates in younger AIV-MDA+ chickens are caused by an H5 antigen-specific block and not by the interference of the AIV-MDA and the vaccine virus itself. In summary, solid protective efficacy and reduced virus transmission were achieved in 3-wk-old AIV-MDA+ chickens, which is relevant especially in regions endemically infected with HPAIV H5N1.

Establishing a Robust Manufacturing Platform for Recombinant Veterinary Vaccines: An Adenovirus-Vector Vaccine to Control Newcastle Disease Virus Infections of Poultry in Sub-Saharan Africa

Developing vaccine technology platforms to respond to pandemic threats or zoonotic diseases is a worldwide high priority. The risk of infectious diseases transmitted from wildlife and domestic animals to humans makes veterinary vaccination and animal health monitoring highly relevant for the deployment of public health global policies in the context of “one world, one health” principles. Sub-Saharan Africa is frequently impacted by outbreaks of poultry diseases such as avian influenza and Newcastle Disease (ND). Here, an adenovirus-vectored vaccine technology platform is proposed for rapid adaptation to ND or other avian viral threats in the region. Ethiopian isolates of the Newcastle Disease virus (NDV) were subjected to sequence and phylogenetic analyses, enabling the construction of antigenically matched vaccine candidates expressing the fusion (F) and hemagglutinin-neuraminidase (HN) proteins. A cost-effective vaccine production process was developed using HEK293 cells in suspension and serum-free medium. Productive infection in bioreactors (1–3 L) at 2 × 10⁶ cells/mL resulted in consistent infectious adenoviral vector titers of approximately 5–6 × 10⁸ TCID₅₀/mL (approximately 10¹¹VP/mL) in the harvest lysates. Groups of chickens were twice immunized with 1 × 10¹⁰ TCID₅₀ of the vectors, and full protection against a lethal NDV challenge was provided by the vector expressing the F antigen. These results consolidate the basis for a streamlined and scalable-vectored vaccine manufacturing process for deployment in low- and medium-income countries.

Sunflower seed oil combined with ginseng stem-leaf saponins as an adjuvant to enhance the immune response elicited by Newcastle disease vaccine in chickens

The present study was to evaluate the adjuvant effect of sunflower seed oil containing saponins extracted from the stem and leaf of Panax ginseng C.A. Meyer (E515-D) on the immune response induced by an inactivated Newcastle disease virus (NDV) in chickens. The results showed that E515-D promoted significantly higher serum NDV-specific HI and neutralizing antibody responses, IFN-γ and IL-4 levels, and lymphocyte proliferative responses to Con A, LPS, and NDV antigen than the conventional adjuvant Marcol 52. Different adjuvant effect between E515-D and Marcol 52 may be attributed to different genes expressed in two groups. Transcriptome analysis of splenocytes showed that there were 1198 differentially expressed genes (DEGs) with 539 up and 659 down regulated in E515-D group while 1395 DEGs with 697 up and 698 down regulated in Marcol 52 group in comparison with the control group. Analysis of gene ontology (GO) term and kyoto encyclopedia of Genes and Genomes (KEGG) pathways showed that the predominant immune related pathways included "Toll-like receptor signaling pathway", "NOD-like receptor signaling pathway", "C-type lectin receptor signaling pathway", and "Phosphatidylinositol signaling system" in E515-D group while Marcol 52 were "NOD-like receptor signaling pathway", "Phagosome", and "Lysosome", and the most relevant DEGs in E515-D group were STAT1, STAT2, PI3K, and IL-6. Considering the excellent adjuvant activity and vegetable origin, E515-D deserves further study as an adjuvant for vaccines used in food animals.

The impact of Aloe vera and licorice extracts on selected mechanisms of humoral and cell-mediated immunity in pigeons experimentally infected with PPMV-1

Background

The aim of the study was to evaluate the impact of herbal extracts on selected immunity mechanisms in clinically healthy pigeons and pigeons inoculated with the pigeon paramyxovirus type 1 (PPMV-1). For the first 7 days post-inoculation (dpi), an aqueous solution of Aloe vera or licorice extract was administered daily at 300 or 500 mg/kg body weight (BW). The birds were euthanized at 4, 7 and 14 dpi, and spleen samples were collected during necropsy. Mononuclear cells were isolated from spleen samples and divided into two parts: one part was used to determine the percentage of IgM⁺ B cells in a flow cytometric analysis, and the other was used to evaluate the expression of genes encoding IFN-γ and surface receptors on CD3⁺, CD4⁺ and CD8⁺ T cells.

Results

The expression of the IFN-γ gene increased in all birds inoculated with PPMV-1 and receiving both herbal extracts. The expression of the CD3 gene was lowest at 14 dpi in healthy birds and at 7 dpi in inoculated pigeons. The expression of the CD4 gene was higher in uninoculated pigeons receiving both herbal extracts than in the control group throughout nearly the entire experiment with a peak at 7 dpi. A reverse trend was observed in pigeons inoculated with PPMV-1 and receiving both herbal extracts. In uninoculated birds, increased expression of the CD8 gene was noted in the pigeons receiving a lower dose of the Aloe vera extract and both doses of licorice extracts. No significant differences in the expression of this gene were found between inoculated pigeons receiving both herbal extracts. The percentage of IgM⁺ B cells did not differ between any of the evaluated groups.

Conclusions

This results indicate that Aloe vera and licorice extracts have immunomodulatory properties and can be used successfully to prevent viral diseases, enhance immunity and as supplementary treatment for viral diseases in pigeons.

Vaccination of broilers against Newcastle disease in the presence of maternally derived antibodies

Objective: The aim of this study was to evaluate the efficacy of a live attenuated vaccine against Newcastle disease in broilers with different levels of maternally derived antibodies (MDA). While vaccination remains the single most important means for controlling Newcastle disease, presence of MDA may interfere with the vaccination of young birds and decrease the efficacy of the vaccine. Materials and methods: Day-old chicks with variable levels of MDA (negative, low and high) were vaccinated with a live attenuated vaccine against Newcastle disease. Three most commonly used inoculation routes were compared; oculonasal, spray and oral (drinking water). Onset and duration of immunity were measured by serology and challenge with virulent virus. Results: Immune response in vaccinated MDA-positive birds was delayed in comparison with SPF controls. Protection was well established already at 14 days post vaccination in SPF birds while in MDA-positive birds it was 1–2 weeks delayed and was lower throughout the study. Non-vaccinated MDA-positive birds lost passive protection completely at 3–4 weeks of age and were significantly more susceptible to challenge than vaccinated hatch mates at all test points. The protection rate increased in vaccinated birds towards the end of the experiment and reached 70–100 % at the last test points (35–42 days of age). Correlation of haemagglutination inhibition (HI) titre vs. protection rate revealed the importance of cellular and local immunity as most of the vaccinated birds with low HI titre were protected, contrary to their unvaccinated hatch mates with the same HI titre. Oculonasal route seems to provide slightly better protection than the other two routes. Conclusions and clinical relevance: Although immune protection in vaccinated MDA-positive birds may be decreased or delayed, vaccination still provides high protection against ND challenge in comparison with the unvaccinated hatch mates. The degree of interference seems to be proportional to the level of MDA. Vaccination schedules therefore need to be designed according to the immune status of the flock.

Quantification and phenotypic characterisation of peripheral IFN-γ producing leucocytes in chickens vaccinated against Newcastle disease

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An avian ICS assay for detection of chIFN-γ was established.

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Commercially available chIFN-γ antibodies were evaluated using tranfected CHO cells.

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Functional T cell responses were addressed in NDV vaccination study.

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Circulating T cells producing IFN-γ were quantified and phenotyped by flow cytometry.

The aim of this study was to optimise and evaluate an intracellular cytokine staining (ICS) assay for assessment of T cell IFN-γ responses in chickens vaccinated against Newcastle disease (ND). We aimed to validate currently available antibodies to chicken IFN-γ using transfected CHO cells. Moreover, this ICS assay was evaluated for use to detect mitogen and antigen induced IFN-γ production in chicken peripheral blood leucocytes.

Chickens from an inbred white leghorn line containing two MHC haplotypes, B19 and B21, were divided into three experimental groups; one group was kept as naive controls, one group was vaccinated intramuscularly twice with a commercial inactivated ND virus (NDV) vaccine, and the last group was vaccinated orally twice with a commercial live attenuated NDV vaccine. PBMC were ex vivo stimulated with ConA or with NDV antigen. The ICS assay was used to determine the phenotype and frequency of IFN-γ positive cells. ConA stimulation induced extensive IFN-γ production in both CD3⁺TCRγδ⁺ (γδ T cells) cells and CD3⁺TCRγδ⁻ cells (αβ T cells), but no significant differences were observed between the experimental groups. Furthermore, a large proportion of the IFN-γ producing cells were CD3⁻ indicating that other cells than classic T cells, secreted this cytokine. NDV antigen stimulation induced IFN-γ production but to a lower extent than ConA and with a large variation between individuals. The CD3⁺TCR1γδ⁻CD8α⁺ (CTL) population produced the highest NDV specific IFN-γ responses, with significantly elevated levels of IFN-γ producing cells in the B19 chickens vaccinated orally with live attenuated NDV vaccine. This was not the case in the B21 animals, indicating a haplotype restricted variation. In contrast, the CD3⁺TCR1γδ⁻CD4⁺ (Th) population did not show a significant increase in IFN-γ production in NDV stimulated samples which was in part due to a high number of IFN-γ producing cells after incubation with medium alone. In conclusion, an ICS assay for phenotyping of IFN-γ producing chicken leukocytes was set up that proved useful in identifying cytokine producing cells upon either mitogen or antigen-specific stimulation.

The role of vaccination in risk mitigation and control of Newcastle disease in poultry

Newcastle disease is regarded as one of the most important avian diseases throughout the world and continues to be a threat and economic burden to the poultry industry. With no effective treatment, poultry producers rely primarily on stringent biosecurity and vaccination regimens to control the spread of this devastating disease. This concise review provides an historical perspective of Newcastle disease vaccination and how fundamental research has paved the way for the development of instrumental techniques which are still in use today. Although vaccination programmes have reduced the impact of clinical disease, they have historically been ineffective in controlling the spread of virulent viruses and therefore do not always offer an adequate solution to the world's food security problems. However, the continued development of novel vaccine technology and improved biosecurity measures through education may offer a solution to help reduce the global threat of Newcastle disease on the poultry industry.

Evaluation of blood monocyte and lymphocyte population in broiler chicken after vaccination and experimental challenge with Newcastle disease virus

In the present study, after vaccination and challenge with Newcastle disease virus, changes in the population of blood monocytes and lymphocytes of broiler chickens were evaluated using flow cytometry. 300 apparently healthy 1-day-old Cobb broiler chicks were divided randomly into four experimental groups (n=75). At 20days of age the chicks in group 1 and 2 were vaccinated with live B1 ND vaccine. Those in group 2 were additionally injected with a killed vaccine simultaneously and group 3 chicks received only the adjuvant of the killed vaccine. The birds in groups 1, 2 and 3 were challenged with a velogenic ND virus and those in group 4 were treated as control. Sampling was done on days 1,2,3,7 after vaccination and also on 1, 2, 3,7,14, 21 post challenge days. In this study percentage of B cell population was increased after vaccination and challenge in vaccinated birds, but CD3+ cells were decreased after vaccination and challenge, which showed B cells have more expansion than T cells. The CD4+ cell percentage in vaccinated birds was always lower than control birds. However, the percentage of CD8+ cells in vaccinated birds was increased. Results indicate increased CMI with the live NDV vaccination. In this study CD4/CD8 ratio in control birds was about 1.5 at 30days of age and it was slightly lower in vaccinated and challenged birds. The percentage of monocytes in vaccinated birds was significantly higher than control birds from 3days post vaccination to the end of the experiment.

A bacterial ghost improves the immunological efficacy of a Newcastle disease virus inactivated vaccine

Newcastle disease (ND) is one of the most common contagious viral infectious diseases of poultry. Vaccination is an effective way to protect chickens from Newcastle disease virus (NDV), and large efforts have been made to acquire not only new vaccines but also new adjuvants to improve the efficiency of existing inactivated vaccines. Here, we observed the adjuvanticity of the bacterial ghost (BG) on the effectiveness of inactivated NDV vaccine in a chicken model. We found that BG, as an adjuvant with inactivated NDV vaccine, substantially strengthened the ND-specific antibody response and protection against lethal challenge in a chicken model, reduced viral shedding, strengthened the time duration of antibody titers, produced an available immunization effect with a low dose of vaccine, and improved serum IL-2 and IFN-γ concentrations. Our results demonstrate that BG significantly improved the immunogenicity of an inactivated NDV vaccine and is a new immune adjuvant candidate.

Immune responses of poultry to Newcastle disease virus

Newcastle disease (ND) remains a constant threat to poultry producers worldwide, in spite of the availability and global employment of ND vaccinations since the 1950s. Strains of Newcastle disease virus (NDV) belong to the order Mononegavirales, family Paramyxoviridae, and genus Avulavirus, are contained in one serotype and are also known as avian paramyxovirus serotype-1 (APMV-1). They are pleomorphic in shape and are single-stranded, non-segmented, negative sense RNA viruses. The virus has been reported to infect most orders of birds and thus has a wide host range. Isolates are characterized by virulence in chickens and the presence of basic amino acids at the fusion protein cleavage site. Low virulent NDV typically produce subclinical disease with some morbidity, whereas virulent isolates can result in rapid, high mortality of birds. Virulent NDV are listed pathogens that require immediate notification to the Office of International Epizootics and outbreaks typically result in trade embargos. Protection against NDV is through the use of vaccines generated with low virulent NDV strains. Immunity is derived from neutralizing antibodies formed against the viral hemagglutinin and fusion glycoproteins, which are responsible for attachment and spread of the virus. However, new techniques and technologies have also allowed for more in depth analysis of the innate and cell-mediated immunity of poultry to NDV. Gene profiling experiments have led to the discovery of novel host genes modulated immediately after infection. Differences in virus virulence alter host gene response patterns have been demonstrated. Furthermore, the timing and contributions of cell-mediated immune responses appear to decrease disease and transmission potential. In view of recent reports of vaccine failure from many countries on the ability of classical NDV vaccines to stop spread of disease, renewed interest in a more complete understanding of the global immune response of poultry to NDV will be critical to developing new control strategies and intervention programs for the future.

Kinetics of the avian influenza-specific humoral responses in lung are indicative of local antibody production

The role and kinetics of respiratory immunoglobulins in AIV infection has not been investigated. In this study we determined the numbers of both total antibody secreting cells (ASC) and virus-specific ASC in lung, spleen, blood and bone marrow (BM) following low-pathogenic AIV infection. Antiviral humoral immune responses were induced both locally in the lung and systemically in the spleen. Responses in the lung and BM preceded responses in the spleen and in blood, with virus-specific IgY ASC already detected in lung and BM from 1 week post-primary inoculation, indicating that respiratory immune responses are not induced in the spleen, but locally in the lung. ASC present in the blood of the lungs and co-isolated during lymphocyte isolation from the lungs have no major impact on the ASC detected in the lungs based on statistical correlation.

Influenza vaccines and vaccination strategies in birds

Although it is well accepted that the present Asian H5N1 panzootic is predominantly an animal health problem, the human health implications and the risk of human pandemic have highlighted the need for more information and collaboration in the field of veterinary and human health. H5 and H7 avian influenza (AI) viruses have the unique property of becoming highly pathogenic (HPAI) during circulation in poultry. Therefore, the final objective of poultry vaccination against AI must be eradication of the virus and the disease. Actually, important differences exist in the control of avian and human influenza viruses. Firstly, unlike human vaccines that must be adapted to the circulating strain to provide adequate protection, avian influenza vaccination provides broader protection against HPAI viruses. Secondly, although clinical protection is the primary goal of human vaccines, poultry vaccination must also stop transmission to achieve efficient control of the disease. This paper addresses these differences by reviewing the current and future influenza vaccines and vaccination strategies in birds.