Newcastle disease virus (NDV) vaccine based on immunization with avian cells expressing the NDV hemagglutinin-neuraminidase glycoprotein

A Booster with a Genotype-Matched Inactivated Newcastle Disease Virus (NDV) Vaccine Candidate Provides Better Protection against a Virulent Genotype XIII.2 Virus

Newcastle disease (ND) is endemic in Bangladesh. Locally produced or imported live Newcastle disease virus (NDV) vaccines based on lentogenic virus strains, locally produced live vaccines of the mesogenic Mukteswar strain, as well as imported inactivated vaccines of lentogenic strains, are being used in Bangladesh under different vaccination regimens. Despite these vaccinations, frequent outbreaks of ND are being reported in Bangladesh. Here we compared the efficacy of booster immunization with three different vaccines in chickens that had been primed with two doses of live LaSota vaccine. A total of 30 birds (Group A) were primed with two doses of live LaSota virus (genotype II) vaccine at days 7 and 28, while 20 birds (Group B) remained unvaccinated. At day 60, birds of Group A were divided into three sub-groups, which received booster immunizations with three different vaccines; A1: live LaSota vaccine, A2: inactivated LaSota vaccine, and A3: inactivated genotype XIII.2 vaccine (BD-C161/2010 strain from Bangladesh). Two weeks after booster vaccination (at day 74), all vaccinated birds (A1-A3) and half of the unvaccinated birds (B1) were challenged with a genotype XIII.2 virulent NDV (BD-C161/2010). A moderate antibody response was observed after the primary vaccination, which substantially increased after the booster vaccination in all groups. The mean HI titers induced by the inactivated LaSota vaccine (8.0 log₂/5.0 log₂ with LaSota/BD-C161/2010 HI antigen) and the inactivated BD-C161/2010 vaccine (6.7 log₂/6.2 log₂ with LaSota/BD-C161/2010 HI antigen) were significantly higher than those induced by the LaSota live booster vaccine (3.6 log₂/2.6 log₂ with LaSota/BD-C161/2010 HI antigen). Despite the differences in the antibody titers, all chickens (A1-A3) survived the virulent NDV challenge, while all the unvaccinated challenged birds died. Among the vaccinated groups, however, 50% of the chickens in Group A1 (live LaSota booster immunization) shed virus at 5- and 7-days post challenge (dpc), while 20% and 10% of the chickens in Group A2 (inactivated LaSota booster immunization) shed virus at 3 and 5 dpc, respectively, and only one chicken (10%) in Group A3 shed virus at 5 dpc. In conclusion, the genotype-matched inactivated NDV booster vaccine offers complete clinical protection and a significant reduction in virus shedding.

Performance comparison of homologous and heterologous Newcastle disease virus in vaccines and antibody tests

Antigenic differences between commercial Newcastle Disease Virus (NDV) vaccine and circulating field virus reduce vaccine efficacy. Fifty-layer chickens were divided into five groups: three vaccinated chicken groups using killed LaSota (Genotype II/GII), Mega, or VD (Genotype VII/GVII) viral strains, negative, and positive control groups. On day 28, Hemagglutination Inhibition (HI) serology of vaccinated chickens was performed using whole virus antigens of RIVS, LaSota, Mega, and VD strains. Sera were also tested with an alternative antigen, using an ELISA to detect antibody for the cleavage site F protein peptide from GII and GVII NDV strains. Vaccinated and unvaccinated positive control birds underwent infectious challenges using VD and Mega strains. HI testing showed that antibody titers were higher when tested using homologous antigens than heterologous antigens. ELISA performed with alternative antigens did not perform as well as the established HI test using homologous strains. Viral shedding was reduced by vaccination that was homologous to the infectious challenge in comparison with vaccination using the LaSota strain virus. We conclude that superior results are obtained when serological testing, vaccinations, and vaccine challenge experiments all use circulating strains of ND virus. Implementation of this recommendation would likely reduce viral shedding by vaccinated chickens and be more effective in preventing outbreaks of virulent NDV.

Development of Plant-Based Vaccines for Prevention of Avian Influenza and Newcastle Disease in Poultry

Viral diseases, including avian influenza (AI) and Newcastle disease (ND), are an important cause of morbidity and mortality in poultry, resulting in significant economic losses. Despite the availability of commercial vaccines for the major viral diseases of poultry, these diseases continue to pose a significant risk to global food security. There are multiple factors for this: vaccine costs may be prohibitive, cold chain storage for attenuated live-virus vaccines may not be achievable, and commercial vaccines may protect poorly against local emerging strains. The development of transient gene expression systems in plants provides a versatile and robust tool to generate a high yield of recombinant proteins with superior speed while managing to achieve cost-efficient production. Plant-derived vaccines offer good stability and safety these include both subunit and virus-like particle (VLP) vaccines. VLPs offer potential benefits compared to currently available traditional vaccines, including significant reductions in virus shedding and the ability to differentiate between infected and vaccinated birds (DIVA). This review discusses the current state of plant-based vaccines for prevention of the AI and ND in poultry, challenges in their development, and potential for expanding their use in low- and middle-income countries.

Recombinant-attenuated Salmonella Pullorum strain expressing the hemagglutinin-neuraminidase protein of Newcastle disease virus (NDV) protects chickens against NDV and Salmonella Pullorum challenge

Newcastle disease virus (NDV) and Salmonella Pullorum have significant damaging effects on the poultry industry, but no previous vaccine can protect poultry effectively. In this study, a recombinant-attenuated S. Pullorum strain secreting the NDV hemagglutinin-neuraminidase (HN) protein, C79-13ΔcrpΔasd (pYA-HN), was constructed by using the suicide plasmid pREasd-mediated bacteria homologous recombination method to form a new bivalent vaccine candidate against Newcastle disease (ND) and S. Pullorum disease (PD). The effect of this vaccine candidate was compared with those of the NDV LaSota and C79-13ΔcrpΔasd (pYA) strains. The serum hemagglutination inhibition antibody titers, serum immunoglobulin G (IgG) antibodies, secretory IgA, and stimulation index in lymphocyte proliferation were increased significantly more (p < 0.01) in chickens inoculated with C79-13ΔcrpΔasd (pYA-HN) than with C79-13ΔcrpΔasd (pYA) but were not significantly increased compared with the chickens immunized with the LaSota live vaccine (p > 0.05). Moreover, the novel strain provides 60% and 80% protective efficacy against the NDV virulent strain F48E9 and the S. Pullorum virulent strain C79-13. In summary, in this study, a recombinant-attenuated S. Pullorum strain secreting NDV HN protein was constructed. The generation of the S. Pullorum C79-13ΔcrpΔasd (pYA-HN) strain provides a foundation for the development of an effective living-vector double vaccine against ND and PD.

Newcastle disease virus: is an updated attenuated vaccine needed?

Newcastle disease virus (NDV) is a major cause of infectious mortality and morbidity in poultry worldwide. It is an enveloped virus with two outer-membrane proteins-haemagglutinin-neuraminidase (HN) and fusion protein (F)-that induce neutralizing antibodies. All NDV strains belong to one serotype. Yet, NDV vaccines, derived from genotype II, do not fully prevent infection or shedding of viruses from other genotypes. The aim of this study was to test if an updated vaccine is required. For this purpose, NDVs isolated from infected, albeit heavily vaccinated, flocks were genetically and immunologically characterized. Amino acid differences in F and HN protein sequences were identified between the vaccine strain and each of the isolates, some specifically at the neutralization sites. Whereas all tested isolates showed similar haemagglutination-inhibition (HI) titres, 100-100,000 times higher antibody-to-virus ratios were needed to neutralize viral propagation in embryos by the field isolates versus the vaccine strain. As a result, a model and an equation were developed to explain the phenomenon of escape in one-serotype viruses and to calculate the HI values needed for protection, depending on variation rate at key positions. In conclusion, to confer full protection against NDVs that differ from the vaccine strain at the neutralizing epitopes, very high levels of antibodies should be raised and maintained to compensate for the reduction in the number of effective epitopes; alternatively, an adjusted attenuated vaccine should be developed-a task made possible in the current era of reverse vaccinology.

Molecular characterization of hemagglutinin-neuraminidase fragment gene of Newcastle disease virus isolated from periodically-vaccinated farms

Background and Aim:

Newcastle disease (ND) caused by avian paramyxovirus serotype-1 (APMV-1) is long known as an acute contagious and infectious disease of various bird species. Prior studies have acknowledged that the virus could cause up to 100% morbidity and mortality as well as reducing eggs production. In theory, hemagglutinin-neuraminidase (HN) in ND virus (NDV) is one of the surface glycoproteins that functions during the attachment, assembly, and maturation of the virus. On the fields, Indonesia has been recognized as an endemic country for ND where continuous outbreaks of ND in commercial chicken farms have been reported despite the implementation of periodical vaccination programs. Thus, this study aims at characterizing NDV isolated from periodically vaccinated commercial farms, comparing its genetic correlation based on their HN gene fragment with registered NDV originated from Indonesia as well as with existing vaccine strains.

Materials and Methods:

The HN gene fragment of NDV isolated from well-vaccinated farms was amplified using primer pairs of forward 5’ GTGAGTGCAACCCCTTTAGGTTGT 3’ and reverse 3’ TAGACCCCAGTGATGCATGAGTTG 3’ with a 694 bp product length. The nucleotide sequences of nine samples, which were gathered from Kulon Progo, Gunung Kidul (2), Boyolali (2), Magelang, Muntilan (2), Palembang, and Medan, were later compared with the sequences of HN gene of NDV available in NCBI Genbank database. The amino acid sequence analysis and multiple sequence alignment were conducted using the Mega7 program.

Result:

The data analysis on amino acid sequences showed that the structure of amino acid residue at positions 345-353 for all isolates appears to be PDEQDYQIR. The structure is the same as for archived samples from Indonesia and either LaSota or B1 vaccine strains. The amino acid distance between observed isolates and LaSota vaccine strain is 8.2-8.8% with a homology value at 91.2-91.7%.

Conclusion:

Looking at amino acid sequence analysis, LaSota vaccines can considerably be stated as being protective against ND disease outbreak. However, the distant homology value from a perfect condition for the protection might have acted as the root cause of vaccination failures.

Improved immunogenicity of Newcastle disease virus inactivated vaccine following DNA vaccination using Newcastle disease virus hemagglutinin-neuraminidase and fusion protein genes

The present study describes the development of DNA vaccines using the hemagglutinin-neuraminidase (HN) and fusion (F) genes from AF2240 Newcastle disease virus strain, namely pIRES/HN, pIRES/F and pIRES-F/HN. Transient expression analysis of the constructs in Vero cells revealed the successful expression of gene inserts in vitro. Moreover, in vivo experiments showed that single vaccination with the constructed plasmid DNA (pDNA) followed by a boost with inactivated vaccine induced a significant difference in enzyme-linked immunosorbent assay antibody levels (p < 0.05) elicited by either pIRES/F, pIRES/F+ pIRES/HN or pIRES-F/HN at one week after the booster in specific pathogen free chickens when compared with the inactivated vaccine alone. Taken together, these results indicated that recombinant pDNA could be used to increase the efficacy of the inactivated vaccine immunization procedure.

Newcastle disease virus fusion protein is the major contributor to protective immunity of genotype-matched vaccine

Virulent strains of Newcastle disease virus (NDV) can cause devastating disease in chickens worldwide. Although the current vaccines are substantially effective, they do not completely prevent infection, virus shedding and disease. To produce genotype-matched vaccines, a full-genome reverse genetics system has been used to generate a recombinant virus in which the F protein cleavage site has been changed to that of avirulent vaccine virus. In the other strategy, the vaccines have been generated by replacing the F and HN genes of a commercial vaccine strain with those from a genotype-matched virus. However, the protective efficacy of a chimeric virus vaccine has not been directly compared with that of a full-genome virus vaccine developed by reverse genetics. Therefore, in this study, we evaluated the protective efficacy of genotype VII matched chimeric vaccines by generating three recombinant viruses based on avirulent LaSota (genotype II) strain in which the open reading frames (ORFs) encoding the F and HN proteins were replaced, individually or together, with those of the circulating and highly virulent Indonesian NDV strain Ban/010. The cleavage site of the Ban/010 F protein was mutated to the avirulent motif found in strain LaSota. In vitro growth characteristics and a pathogenicity test indicated that all three chimeric viruses retained the highly attenuated phenotype of the parental viruses. Immunization of chickens with chimeric and full-length genome VII vaccines followed by challenge with virulent Ban/010 or Texas GB (genotype II) virus demonstrated protection against clinical disease and death. However, only those chickens immunized with chimeric rLaSota expressing the F or F plus HN proteins of the Indonesian strain were efficiently protected against shedding of Ban/010 virus. Our findings showed that genotype-matched vaccines can provide protection to chickens by efficiently preventing spread of virus, primarily due to the F protein.

Preparation and diagnostic utility of a hemagglutination inhibition test antigen derived from the baculovirus-expressed hemagglutinin-neuraminidase protein gene of Newcastle disease virus

A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 2(13) per 25 μL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4°C. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays.

Evaluation of the Newcastle disease virus F and HN proteins in protective immunity by using a recombinant avian paramyxovirus type 3 vector in chickens

Newcastle disease virus (NDV) belongs to serotype 1 of the avian paramyxoviruses (APMV-1) and causes severe disease in chickens. Current live attenuated NDV vaccines are not fully satisfactory. An alternative is to use a viral vector vaccine that infects chickens but does not cause disease. APMV serotype 3 infects a wide variety of avian species but does not cause any apparent disease in chickens. In this study, we constructed a reverse-genetics system for recovery of infectious APMV-3 strain Netherlands from cloned cDNAs. Two recombinant viruses, rAPMV3-F and rAPMV3-HN, were generated expressing the NDV fusion (F) and hemagglutinin-neuraminidase (HN) proteins, respectively, from added genes. These viruses were used to immunize 2-week-old chickens by the oculonasal route in order to evaluate the contribution of each protein to the induction of NDV-specific neutralizing antibodies and protective immunity. Each virus induced high titers of NDV-specific hemagglutination inhibition and serum neutralizing antibodies, but the response to F protein was greater. Protective immunity was evaluated by challenging the immunized birds 21 days later with virulent NDV via the oculonasal, intramuscular, or intravenous route. With oculonasal or intramuscular challenge, all three recombinant viruses (rAPMV3, rAPMV3-F, and rAPMV3-HN) were protective, while all unvaccinated birds succumbed to death. These results indicated that rAPMV3 alone can provide cross-protection against NDV challenge. However, with intravenous challenge, birds immunized with rAPMV3 were not protected, whereas birds immunized with rAPMV3-F alone or in combination with rAPMV3-HN were completely protected, and birds immunized with rAPMV3-HN alone were partially protected. These results indicate that the NDV F and HN proteins are independent neutralization and protective antigens, but the contribution by F is greater. rAMPV3 represents an avirulent vaccine vector that can be used against NDV and other poultry pathogens.

Structure and expression of endogenous retroviral sequences in the permanent LMH chicken cell line

From DNA mapping data, four endogenous proviral loci have been observed in the chicken permanent cell line LMH. The locus corresponding to endogenous virus (ev) ev1 is present in duplicate whereas the locus corresponding to ev3 is present in one copy. The other loci are probably ev6 and a solitary long terminal repeat. A RNA Northern blot analysis revealed both ev3 and ev6 transcripts but no ev1 transcript was detected. Using avian leukosis virus (ALV)-based vectors, transcomplementing assays were performed. They demonstrate the correct expression and maturation of endogenous env proteins and the absence of production of functional gag and pol components, indicating that these cells are not competent for viral production.

Packaging cells for avian leukosis virus-based vectors with various host ranges

Using our previously described Haydée semipackaging cell line (F. L. Cosset, C. Legras, Y. Chebloune, P. Savatier, P. Thoraval, J. L. Thomas, J. Samarut, V. M. Nigon, and G. Verdier, J. Virol. 64:1070-1078, 1990) which produces avian leukosis virus gag and pol proteins, we have constructed packaging cells with subgroups B, C, and E envelope specificities. This allows us to produce helper-free avian leukosis virus particles carrying the lacZ reporter gene and the A, B, C, or E subgroup specificities. Titers of the recombinant lacZ virus are shown to be dependent upon the type of the env subgroup and the target avian cell.