Live Newcastle Disease Virus Research Articles

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.

A novel avian retrovirus associated with lymphocytoma isolated from a local Chinese flock induced significantly reduced growth and immune suppression in SPF chickens

Avian Leukosis Viruses (ALVs) are associated with neoplasias, immune suppression and reduced performance in chicken flocks. In the present study, a naturally occurring recombinant strain of ALV (FJ15HT0) was isolated from an infected flock of Chinese “Hetian” chickens, and was subsequently identified as an exogenous ALV by immuno-fluorescence assay (IFA), PCR and following entire proviral DNA nucleotide sequencing. This isolate is revealed as a novel recombinant virus, lacking viral oncogenes, with the gp85 (93.4%) of subgroup B, the U3 (92.1%) and R (95.2%) region of subgroup J, the U5 (93.8%) region and 5′UTR (95.7%) of subgroup C, as well as the gp37 (90.6%) and 3′ (92.2%) of ALV-E. The simulative congenital infection with this isolate in SPF chickens resulted in significant weight loss (P<0.05) and a significant reduction in the humoral immune response to the live NDV vaccine (P<0.05), but not to the inactive AIV-H5 vaccine (P>0.05). Foci of lymphocytomas were observed in tissues of congenitally infected chickens at 11 weeks post-hatch, demonstrating the acute oncogenicity of the isolate.

Overview of current advances in the development of subunit and recombinant vaccines against Newcastle disease virus

Newcastle disease virus (NDV) is one of the most important viral pathogens of avian species and the causative agent of atypical fowl plague, a highly contagious and economically important disease characterized by high mortality rates and reduction of egg production. The HN and F proteins are the main targets for immune response to NDV. Vaccination of poultry with live and inactivated NDV vaccines is the most effective method of control and prevention of Newcastle disease, however due to their disadvantages, efforts are being invested into developing subunit vaccines. To this end, the NDV HN and/or F protein have been expressed using different viruses as vectors, but have also been expressed using transgenic plant systems, yeast and lactic acid bacteria in order to produce the NDV subunit vaccine. Many authors have investigated the possibility of preparation of vaccines from purified and biologically active NDV subunits with HN and F glycoproteins, purified from nucleocapsids, viral ribonucleic acid (RNA) and pyrogens. The above mentioned viral glycoproteins with preserved antigenic structure and biological activities can be used as subunit vaccinal antigens due to their immunogenic properties.

The Negative Impact of Chicken Infectious Anemia Virus Infection on Immune Responses to Different Newcastle Disease Virus Vaccination Programs

Chicken infectious anemia virus (CIAV) is among the naturally occurring viruses that cause immunosuppression in chickens. In the present study, the impact of CIAV infection on both NDV vaccination immune responses and bird performance were demonstrated. Post CIAV infection, the mean live body weights of the ND-vaccinated groups showed improvement compared with the non-NDV vaccinated groups. The immunosuppressive effects of CIAV infection was higher and more obvious on live ND vaccinated group compared with the other vaccinated groups. The vaccination with combination of live and inactivated vaccines showed better HI-NDV Ab responses especially when inactivated vaccine was administrated at 9 days (group II). In consistent, both the phagocytic Percent and Index were lower in case of vaccination with live NDV vaccine only and CIAV infection. Birds were vaccinated with both live and inactivated NDV vaccines at different time points showed superior protection rate (100%) compared with the other groups. Microscopically, CIAV infection led to severe deterioration in the lymphoid tissues (thymus, bursa, spleen and bone marrow) such as focal to diffuse depletion of lymphocytes and hematopoietic cells. This study highlights the negative impact of CIAV infection on both bird performance and immune status.

Immunosuppressive effects of arsenic in broiler chicks exposed to Newcastle disease virus

To assess the effects of prolonged exposure to arsenic (As, as arsenate) on host immune competence overall and resistance to Newcastle disease (ND) viral infection in particular, a study was carried out in broiler chicks. At 7 days of age, chicks were assigned to groups that would undergo varying vaccination, challenge, and/or As exposures; Group 1 was a control; Group 2 was to receive Newcastle disease virus (NDV) only; two groups (Groups 3, 4) were to be given As daily (50 mg/kg, by gavage) from Days 7–35 of the experiment. All groups underwent normal vaccination on Days 5, 23, and 32 against live NDV (B1 type, LaSota strain); two groups (Groups 2, 4) were challenged with field-isolated NDV at Day 24. At Days 14, 21, 28, and 35 of age, subsets of chicks in each group were evaluated. The results showed feed intake and weight gain were lower in As-treated and NDV-challenged chicks. In As-treated chicks, absolute and relative spleen weights were significantly greater, whereas those of the thymus significantly lower, over the entire 35-day period. Effects on bursa weights (absolute, relative) were only significantly reduced through Day 21. Antibody titers against ND were significantly reduced (vs. control) over the whole 35 days in birds that received As alone, but only significantly depressed through the first 21 days in birds that received As + NDV; thereafter, titers were significantly greater (in parallel with effects in birds that received NDV alone). In contrast, antibody responses to T-dependent antigen (Sheep red blood cells [SRBC]) were significantly lower in As only- and As + NDV-treated chicks throughout the study period. Among birds exposed to As (alone or with NDV), in situ phagocytic activity was elevated and cutaneous sensitivity responses decreased during the period from Day 28 to Day 35. NDV alone had spurious effects on phagocytic activity but did cause significant reductions in cutaneous sensitivity responses. It was concluded that arsenic decreased immunity in broiler chicks, thereby making them prone to ND.

LaSota fusion (F) cleavage motif-mediated fusion activity is affected by other regions of the F protein from different genotype Newcastle disease virus in a chimeric virus: implication for virulence attenuation.

The cleavage site sequence of the fusion (F) protein contributes to a wide range of virulence of Newcastle disease virus (NDV). In this study, we identified other important amino acid sequences of the F protein that affect cleavage and modulation of fusion. We generated chimeric Beaudette C (BC) viruses containing the cleavage site sequence of avirulent strain LaSota (Las-Fc) together with various regions of the F protein of another virulent strain AKO. We found that the F1 subunit is important for cleavage inhibition. Further dissection of the F1 subunit showed that replacement of four amino acids in the BC/Las-Fc protein with their AKO counterparts (T341S, M384I, T385A and I386L) resulted in an increase in fusion and replication in vitro. In contrast, the mutation N403D greatly reduced cleavage and viral replication, and affected protein conformation. These findings will be useful in developing improved live NDV vaccines and vaccine vectors.

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.

Strains of Newcastle disease Virus, Circulating among Sick Poultry Flocks in Nsukka-Nigeria

Aim: To study prevalence of the different strains of Newcastle disease virus (NDV) circulating among sick poultry flocks, NDV detected from disease outbreaks in Nsukka-Nigeria were characterized into the three main NDV strains. Materials and Methods: NDV was detected from 63 cases of poultry disease that manifested clinical signs and lesions suggestive of Newcastle disease (ND), by the haemagglutination test. The detected NDV samples were characterized by a combination of their ability to agglutinate mammalian erythrocytes and their erythrocyte elution time (EET). Results: Fifty three out of 63 (84%) NDV samples detected from the ND cases belonged to Lentogenic strains while 10 (16%) were Mesogenic strains. None was of the Velogenic strains. Conclusion: Rates of circulation of Lentogenic, Mesogenic and Velogenic NDV strains among sick poultry flocks in Nsukka- Nigeria suggest that the practice of using live NDV vaccines for prophylaxis may be an important factor in epizootiology of Newcastle disease in the country.

Development of an improved vaccine evaluation protocol to compare the efficacy of Newcastle disease vaccines

While there is typically 100% survivability in birds challenged with vNDV under experimental conditions, either with vaccines formulated with a strain homologous or heterologous (different genotype) to the challenge virus, vaccine deficiencies are often noted in the field. We have developed an improved and more stringent protocol to experimentally evaluate live NDV vaccines, and showed for the first time under experimental conditions that a statistically significant reduction in mortality can be detected with genotype matched vaccines. Using both vaccine evaluation protocols (traditional and improved), birds were challenged with a vNDV of genotype XIII and the efficacy of live heterologous (genotype II) and homologous (genotype XIII) NDV vaccines was compared. Under traditional vaccination conditions there were no differences in survival upon challenge, but the homologous vaccine induced significantly higher levels of antibodies specific to the challenge virus. With the more stringent challenge system (multiple vaccine doses and early challenge with high titers of vNDV), the birds administered the homologous vaccine had superior humoral responses, reduced clinical signs, and reduced mortality levels than those vaccinated with the heterologous vaccine. These results provide basis for the implementation of more sensitive methods to evaluate vaccine efficacy.

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.

English

This study was designed to characterize a field isolate of Newcastle disease virus (NDV) to check its suitability as an inactivated vaccine and to determine the comparative efficacy of this inactivated NDV vaccine with conventional live vaccines, Baby Chick Ranikhet Disease Vaccine (BCRDV, F strain) and Ranikhet Disease Vaccine (RDV, Mukteswar strain). The field isolate of NDV was identified as velogenic strain based on the pathogenicity indices {mean death time (MDT), intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI)}. Formalin precipitated inactivated NDV vaccine was prepared from the field isolate and adjuvanted with aluminium hydroxide. The comparative efficacy of three distinct vaccination schedules (Group A, inactivated vaccine three times only; group B, BCRDV followed by inactivated and group C, BCRDV followed by RDV) was then evaluated on the basis of haemagglutination inhibition (HI) antibody titre of sera samples collected at day 4, 27, 55 and 72 of post vaccinated chicks. The prepared inactivated vaccine with the field isolate induced satisfactory level of antibody following vaccination in chicken. Combined vaccination in chickens with live BCRDV followed by inactivated NDV vaccine induced better immune response than the live or inactivated NDV vaccine alone. The antibody titre though differed significantly (P &lt;0.05, group B versus group C at 55- and 72-days and group B versus group A at 72 days) in the chickens among the vaccinated groups, the protection rate was 100% in all groups following virulent challenge infection. Key words: &nbsp;Newcastle disease virus, vaccine, velogenic, haemagglutination inhibition (HI), antibody.

Evaluation of avian paramyxovirus serotypes 2 to 10 as vaccine vectors in chickens previously immunized against Newcastle disease virus

Newcastle disease virus (NDV), also known as avian paramyxovirus (APMV) serotype 1, is used as a vaccine vector to express the hemagglutinin protein of avian influenza (AI) virus. However, use of live NDV recombinant vaccines expressing AI virus hemagglutinin is not desirable in emergency vaccination programs to control severe AI outbreaks in chickens, because commercial chickens often possess pre-existing NDV immunity induced by routine vaccination. Therefore, a novel vaccine vector is required for emergency vaccination of chickens to control AI during outbreaks. We investigated whether candidate APMV strains could be used as vaccine vectors that could evade the pre-existing immunity acquired by chickens through NDV vaccination and that would replicate in the mucosal tissues where AI virus primarily replicates. To this end, we examined strains of APMV serotypes 2 to 10 for their immunogenicity and replication in chickens with pre-existing immunity to NDV. APMV serotypes 2, 6, and 10 were the least cross-reactive to antibodies to NDV in hemagglutination inhibition and/or virus neutralization tests. Virus replication in mucosal tissues, as well as antibody response after oculonasal inoculation, was observed when 7-week-old chickens were challenged with APMV of serotype 2, 6, or 10. The APMV also replicated in mucosal tissues and induced antibody responses in chickens that had been vaccinated twice with NDV before challenge. These results warrant further study to develop vaccine vectors based on APMV serotype 2, 6, or 10 for emergency vaccination of chickens against AI.

Detection and characterization of Newcastle disease virus in formalin-fixed, paraffin-embedded tissues from commercial broilers in Egypt.

Newcastle disease (ND) is highly contagious and causes severe economic losses to the poultry industry due to high morbidity and mortality. In this report, we describe the detection of Newcastle disease virus (NDV) in formalin-fixed tissues from an outbreak of ND on broiler farms in Egypt. The affected birds experienced respiratory and/or nervous signs and a 75% mortality rate. Tissue samples were collected and placed in 10% neutral buffered formalin followed by embedding in paraffin. RNA was extracted from 80-microm formalin-fixed paraffin-embedded tissue blocks and recovered in 60 microl of elution buffer. All samples were negative for influenza virus by real-time reverse-transcription (RT)-PCR but positive for NDV. These flocks were known to have been vaccinated with a live NDV vaccine (LaSota strain). The nucleic acid sequences of the virus detected in this study were similar to those of a velogenic virus at its cleavage site 111GRRQKR*F117 and clustered with class II genogroup VII lineage of NDV, with a nucleotide sequence identity of 94%-99%. Although extraction and amplification of NDV from paraffin-embedded tissues from experimentally infected birds has been reported previously, this study reports on the use of RT-PCR on formalin-fixed tissues from actual field samples.

Protection Conferred by a Live Avian Metapneumovirus Vaccine when Co-Administered with Live La Sota Newcastle Disease Vaccine in Chicks

This paper examines the effects on specific pathogen-free (SPF) chicks when avian metapneumovirus (aMPV) and Newcastle disease virus (NDV) La Sota strain vaccines are co-administered. Day-old SPF chicks were divided into five groups. The first group was inoculated with sterile water (SW) and the rest of the groups were inoculated with live NDV vaccine VG/GA by the oculo-oral route. At 21 days-old, the unvaccinated chicks were again inoculated with SW. The four VG/GA-vaccinated groups were further inoculated with (i) SW, (ii) live aMPV vaccine, (iii) live NDV La Sota, or (iv) combined live NDV La Sota and live aMPV, respectively. Chicks were monitored for post-vaccination reactions and oropharyngeal swabs were collected for vaccines detection. Blood samples were collected to detect aMPV ELISA and NDV haemagglutination-inhibition antibodies. Twenty-one days following the second vaccination, six chicks from each group were challenged with virulent NDV or aMPV respectively. Chicks were monitored for clinical signs and mortality and oropharyngeal swabs collected for aMPV detection. Results showed that, when challenged with a virulent aMPV, both chicks previously vaccinated with VG/GA and subsequently given aMPV vaccine singly or in combination with La Sota were equally protected against clinical signs. Chicks that were vaccinated against NDV either once with VG/GA or followed by La Sota (singly or in combination with aMPV) were fully protected when challenged with velogenic NDV. We concluded that simultaneous administration of live aMPV and NDV La Sota vaccines have no adverse effects on protection conferred by either live vaccine.

Effects of Newcastle disease virus vaccine antibodies on the shedding and transmission of challenge viruses

Different genotypes of avian paramyxovirus serotype-1 virus (APMV-1) circulate in many parts of the world. Traditionally, Newcastle disease virus (NDV) is recognized as having two major divisions represented by classes I and II, with class II being further divided into sixteen genotypes. Although all NDV are members of APMV-1 and are of one serotype, antigenic and genetic diversity is observed between the different genotypes. Reports of vaccine failure from many countries and reports by our lab on the reduced ability of classical vaccines to significantly decrease viral replication and shedding have created renewed interest in developing vaccines formulated with genotypes homologous to the virulent NDV (vNDV) circulating in the field. We assessed how the amount and specificity of humoral antibodies induced by inactivated vaccines affected viral replication, clinical protection and evaluated how non-homologous (heterologous) antibody levels induced by live NDV vaccines relate to transmission of vNDV. In an experimental setting, all inactivated NDV vaccines protected birds from morbidity and mortality, but higher and more specific levels of antibodies were required to significantly decrease viral replication. It was possible to significantly decrease viral replication and shedding with high levels of antibodies and those levels could be more easily reached with vaccines formulated with NDV of the same genotype as the challenge viruses. However, when the levels of heterologous antibodies were sufficiently high, it was possible to prevent transmission. As the level of humoral antibodies increase in vaccinated birds, the number of infected birds and the amount of vNDV shed decreased. Thus, in an experimental setting the effective levels of humoral antibodies could be increased by (1) increasing the homology of the vaccine to the challenge virus, or (2) allowing optimal time for the development of the immune response.

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.

Protective Efficacy of Newcastle Disease Virus Expressing Soluble Trimeric Hemagglutinin against Highly Pathogenic H5N1 Influenza in Chickens and Mice

BackgroundHighly pathogenic avian influenza virus (HPAIV) causes a highly contagious often fatal disease in poultry, resulting in significant economic losses in the poultry industry. HPAIV H5N1 also poses a major public health threat as it can be transmitted directly from infected poultry to humans. One effective way to combat avian influenza with pandemic potential is through the vaccination of poultry. Several live vaccines based on attenuated Newcastle disease virus (NDV) that express influenza hemagglutinin (HA) have been developed to protect chickens or mammalian species against HPAIV. However, the zoonotic potential of NDV raises safety concerns regarding the use of live NDV recombinants, as the incorporation of a heterologous attachment protein may result in the generation of NDV with altered tropism and/or pathogenicity.Methodology/Principal FindingsIn the present study we generated recombinant NDVs expressing either full length, membrane-anchored HA of the H5 subtype (NDV-H5) or a soluble trimeric form thereof (NDV-sH53). A single intramuscular immunization with NDV-sH53 or NDV-H5 fully protected chickens against disease after a lethal challenge with H5N1 and reduced levels of virus shedding in tracheal and cloacal swabs. NDV-sH53 was less protective than NDV-H5 (50% vs 80% protection) when administered via the respiratory tract. The NDV-sH53 was ineffective in mice, regardless of whether administered oculonasally or intramuscularly. In this species, NDV-H5 induced protective immunity against HPAIV H5N1, but only after oculonasal administration, despite the poor H5-specific serum antibody response it elicited.Conclusions/SignificanceAlthough NDV expressing membrane anchored H5 in general provided better protection than its counterpart expressing soluble H5, chickens could be fully protected against a lethal challenge with H5N1 by using the latter NDV vector. This study thus provides proof of concept for the use of recombinant vector vaccines expressing a soluble form of a heterologous viral membrane protein. Such vectors may be advantageous as they preclude the incorporation of heterologous membrane proteins into the viral vector particles.