Genotype Diversity of Newcastle Disease Virus in Nigeria: Disease Control Challenges and Future Outlook

Evaluating the impact of avian paramyxovirus type 1 infection in poultry at live bird markets in Nigeria: defining hurdles to sustainable agriculture

BACKGROUND

Infectious diseases including Newcastle disease (ND) impair poultry productivity and represent a significant burden to sustainable agriculture in Nigeria. This study aimed to investigate the active circulation and seroprevalence of Newcastle disease virus (NDV) caused by virulent forms of avian paramyxovirus type-1 (APMV-1) in poultry at live bird markets (LBMs) across Nigeria.

METHODS

A cross-sectional study of 18 LBMs was conducted within three states in Nigeria (Kano, Oyo, and Abuja). Paired swab and tissue samples (n = 413) were collected from birds on FTA cards and tested for APMV-1 using real-time reverse transcription polymerase chain reaction (rRT-PCR). A subset of rRT-PCR-positive samples were selected for whole genome sequencing based on the originating species (chicken, duck, geese), date, and market location to provide a broad range of isolates for characterisation. Blood samples (n = 405) were also collected from birds and the seroprevalence of APMV-1 antibodies was measured using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

APMV-1 RNA was detected in 21.5% (89/413) of samples from LBMs by rRT-PCR. At least one APMV-1 positive sample was detected in 55.6% (10/18) of LBMs. The largest proportion of APMV-1-positive markets was in Kano (83.3%, 5/6), whereas the lowest was in Oyo (16.7%, 1/6). Assessment of genetic data demonstrated that genotype XIV.2 APMV-1 was circulating within Nigeria with the viruses detected clustering closely with other Nigerian isolates described previously. The seroprevalence of APMV-1 in birds was 45.9% (186/405) and 94.4% (17/18) of LBMs had at least one APMV-1 seropositive sample (i.e., with at least one APMV-1-antibody-positive bird). The LBMs in Kano had the lowest seroprevalence (88.3%, 5/6).

CONCLUSIONS

This study demonstrated that APMV-1 continues to circulate in LBMs in Nigeria. LBM traders, poultry producers, and related industry and policy stakeholders should be aware of the occurrence of APMV-1 and how ND may negatively impact upon poultry production and the livelihoods of poultry farmers and LBM traders. Training initiatives aimed at improving the knowledge of APMV-1 infection and improvements in biosecurity practises and the role of disease mitigation through vaccination are required to reduce the impact of this threat to food security.

Molecular characterization of Newcastle disease virus (AOAV-1) obtained from Western region of Libya

Background

Since its discovery in 1926, Newcastle disease (ND) is still emerging in many avian species worldwide causing severe economic losses due to high mortality.

Aim

This article aims to discuss the challenge of virulent ND in poultry in Libya, focusing on recent outbreaks investigated in Alzintan, Alrayaina, Nalut, and Surman, cities located in the western region of Libya.

Methods

Clinical signs and lesions were recorded. Tissues, as well as tracheal and cloacal swabs, were collected. RNA extraction was performed for confirmation using PCR and sequencing.

Results

Mortality, in general, reached 50%-100% in vaccinated flocks with respiratory distress, diarrhea, swelling of the face, and nasal discharges. Necropsy revealed severe hemorrhages in the proventriculus, necrosis, and hemorrhages in the intestine and cecal tonsils. All tested samples were positive for avian orthoavulavirus 1 (AOAV-1) using rRT-PCR and genetic analysis. The sequences obtained are referable to AOAV-1, which is the same strain in all tested samples. The amino acid sequences deduced from the cleavage site of the F protein are referable to a velogenic strain of AOAV-1 belonging to genotype VII.2. The detected strains in the current study revealed 86%-91% identity with European isolates identified between 2020 and 2022 and isolates from Asia and Africa and 97% identity to the previous isolated Libyan strains in 2013 and 2016. It is slightly different by the presence of amino acid lycine at position 111 on the cleavage site of the F0 gene as compared to previous Libyan strains in which arginine was found in the same position. The nucleotide sequence at this position changed from (aga) in AOAV-1 strains of years 2013 and 2016 to (aag) of the year 2023.

Conclusion

ND remains a significant threat to the poultry industry in Libya. Therefore, there is an urgent need to conduct an epidemiological study with a representative number of samples from all regions of the country, alongside the implementation of an inactivated vaccine targeting genotype VII.

Detection of Avian Orthoavulavirus-1 genotypes VI.2.1 and VII.1.1 with neuro-viscerotropic tropism in some backyard pigeons (Columbidae) in Eastern Saudi Arabia

Introduction

Avian orthoavulavirus-1 (AOAV1) has a wide host range, including domestic and wild birds. The present study aimed to identify the currently circulating AOAV1 strains from some outbreaks in some backyard pigeons in the eastern region of Saudi Arabia (ERSA).

Methods

Tracheal/cloacal swabs and tissue specimens were collected from eight backyards in Al-Ahsa, ERSA, between January 2021 and March 2023. Samples were tested for the presence of AOAV1 using commercial real-time RT-PCR. Part of the fusion gene was also amplified by gel-based RT-PCR, and the obtained amplicons were sequenced.

Results and discussion

AOAV1 was detected in samples from the eight flocks. The retrieved sequences from samples of 6/8 pigeon backyards are reported. Phylogenetic analysis based on the obtained sequences from these backyard pigeons showed the segregation of the obtained sequences in AOAV1 genotypes VI.2.1 and VII.1.1. Clinically, nervous manifestations were dominant in pigeons infected with both genotypes. Respiratory manifestations and significantly higher overall mortality rate were induced by genotype VI.2.1. The deduced amino acid sequences of the fusion protein cleavage site (FPCS) showed that all the detected isolates belong to velogenic strains. Differences in clinical profiles induced by the natural infection of pigeons with AOAV1 genotypes VI.2.1 and VII.1.1 were reported. The present findings highlight the potential roles of some backyard pigeons in the long-distance spread and cross-species transmission of the reported AOAVI genotypes. Further research is required to perform biotyping and pathotyping of the reported strains.

Epidemiological distribution of respiratory viral pathogens in marketable vaccinated broiler chickens in five governorates in the Nile Delta, Egypt, from January 2022 to October 2022

Background and Aim

Respiratory viral infections significantly negatively impact animal welfare and have significant financial implications in the poultry industry. This study aimed to determine the frequency of the most economically relevant respiratory viruses that circulated in Egyptian chicken flocks in 2022.

Materials and Methods

Chickens from 359 broiler flocks in five different Egyptian governorates in the Nile Delta (Beheira, Gharbia, Giza, Monufiya, and Qalyoubia) at marketing time (33-38 days of age) were used in this study. Combined oropharyngeal and cloacal swabs and tissue samples were collected from clinically diseased or freshly dead birds suffering from respiratory disease. Avian influenza (AI)-H5, AI-H9, Newcastle disease (ND), and infectious bronchitis virus (IBV) were analyzed by reverse transcriptase polymerase chain reaction.

Results

Of the 359 flocks examined, 293 tested positive, whereas 66 were completely negative for the four viruses evaluated, with the highest positive results in Beheira. Out of 293 positive flocks, 211 were positive for a single virus, with Beheira having the highest rate, followed by Qalyoubia, Giza, and Monufiya. ND virus (NDV) was found to be the highest across all governorates, followed by IBV, AI-H9, and AI-H5. A double infection was detected in 73 flocks with either H9 or ND, or both H9 and IB could coinfect each other. The most common viral coinfections were H9 + IB, ND + IB, and ND + H9. Giza had the highest prevalence of ND + H9, H9 + IB, and ND + IB coinfection in the governorates, followed by Monufiya and Beheira. Only six out of 359 flocks were tribally infected with ND + H9 + IB in Giza, Monufiya, and Beheira governorates. On the basis of the number of flocks and the month of the year, July had the lowest number of flocks (23), while September and October had the highest number (48 flocks). Positive flock numbers were highest in October and lowest in January.

Conclusion

From January to October 2022, prevalent respiratory viral infections (H5N1, NDV, H9N2, and IBV) were detected in broiler chickens across the Delta area governorate, according to the findings of the present study. In addition, IBV and H9, either alone or in combination, significantly contributed to the respiratory infection observed in broiler chickens. Regardless of the type and origin of the vaccine used, it is not possible to protect broiler chickens from the development of the infection and the subsequent dissemination of the virus into the poultry environment. In the presence of face-infectious field virus mutations, poultry vaccinations must be regularly reviewed and updated, and poultry farms must take further biosecurity measures.

Molecular characterization and phylogenetic analysis of Newcastle disease viruses isolated in southern Angola, 2016-2018

Newcastle disease (ND) is a highly contagious viral disease that affects many bird species worldwide. This study presents the results of the molecular characterization and phylogenetic analysis of 15 virulent ND viruses (NDV) isolated from chickens during outbreaks reported in 2016 and 2018, in the provinces of Namibe and Huíla, in southern Angola. A 561-nucleotide fragment of the F gene was amplified by RT-PCR and sequenced for molecular characterization. Results showed that in all isolates the amino acid sequence comprising the cleavage site of fusion protein is characteristic of virulent viruses (RRQKR/F). Blast analysis revealed high similarity (99.2%) between two isolates from Huíla province, HLA4 and HLA6, and strain 5620 (GenBank accession number KY747479) isolated from chickens in the neighboring country Namibia, in 2016. The other isolates investigated are more related (97.0%) with strain 6195 (GenBank accession number KY747480), also isolated in Namibia in 2016. Phylogenetic analysis performed by Maximum Likelihood, Neighbor-joining and Bayesian methods revealed that like the strains isolated in Namibia, the isolates from southern Angola also belong to subgenotype 2 of genotype VII (VII.2). The network analysis revealed that NBA1 isolate from Angola is closer to a common ancestor than the isolates from Namibia, suggesting that transmission of ND viruses occurred from Angola to Namibia.

Genetic Diversity of Newcastle Disease Virus Involved in the 2021 Outbreaks in Backyard Poultry Farms in Tanzania

Newcastle disease virus is a significant avian pathogen with the potential to decimate poultry populations all over the world and cause enormous economic losses. Distinct NDV genotypes are currently causing outbreaks worldwide. Due to the high genetic diversity of NDV, virulent strains that may result in a lack of vaccine protection are more likely to emerge and ultimately cause larger epidemics with massive economic losses. Thus, a more comprehensive understanding of the circulating NDV genotypes is critical to reduce Newcastle disease (ND) burden. In this study, NDV strains were isolated and characterized from backyard poultry farms from Tanzania, East Africa in 2021. Reverse-transcription polymerase chain reaction (RT-PCR) based on fusion (F) gene amplification was conducted on 79 cloacal or tracheal swabs collected from chickens during a suspected ND outbreak. Our results revealed that 50 samples out 79 (50/79; 63.3%) were NDV-positive. Sequencing and phylogenetic analyses of the selected NDV isolates showed that 39 isolates belonged to subgenotype VII.2 and only one isolate belonged to subgenotype XIII.1.1. Nucleotide sequences of the NDV F genes from Tanzania were closely related to recent NDV isolates circulating in southern Africa, suggesting that subgenotype VII.2 is the predominant subgenotype throughout Tanzania and southern Africa. Our data confirm the circulation of two NDV subgenotypes in Tanzania, providing important information to design genotype-matched vaccines and to aid ND surveillance. Furthermore, these results highlight the possibility of the spread and emergence of new NDV subgenotypes with the potential of causing future ND epizootics.

Analysis of Amino Acid Changes in the Fusion Protein of Virulent Newcastle Disease Virus from Vaccinated Poultry in Nigerian Isolates

The roles of fusion gene in the virulence of Newcastle disease virus are well established, but the extent of its variation among the XIV, XVII, and XVIII genotypes reported in Central Africa and West Africa has until recently been understudied. In this study, virulent Newcastle disease virus (vNDV) was isolated from dead chickens among vaccinated flocks between March and April 2020. Fusion (F) gene was sequenced and analysed for characterization and information about genetic changes. Many substitutions were observed along the region and some of their functions are yet to be determined. Results showed that all study isolates have virulent cleavage site sequence 112-RRRKR-116/F117 and clustered within genotype XIVb. Sequence analysis showed K78R mutation in the A2 antigenic epitope in all isolates and more along the F-gene which varied in some instances within the isolates. Mutation in this A2 antigenic epitope has been reported to induce escape mutation to monoclonal antibodies generated using the NDV LaSota strain. The range of percentage nucleotide and amino acid homology between the study isolates and commercially available vaccine strains is 81.14%-84.39% and 0.175-0.211, respectively. This report provides evidence of vNDV among vaccinated chicken flock and molecular information about circulating vNDV strains in Kano State, Nigeria, which is useful for the development of virus matched vaccines. Newcastle disease (ND) surveillance and molecular analysis of circulating strains in this region should be encouraged and reported. Furthermore, ND outbreaks or cases among vaccinated poultry presented to veterinary clinics should be reported to the state epidemiologist. Nucleotide sequences were assigned accession numbers OK491971-OK491977.

A study of risk factors associated with Newcastle disease and molecular characterization of genotype XIII Newcastle disease virus in backyard and commercial poultry in Assam, India

The continuous emergence of Newcastle disease virus (NDV) poses a persistent threat to the poultry industry. Recent increasing outbreaks of NDV in the North East region of India have highlighted the need to closely monitor and analyze the potential risk factors for Newcastle disease (ND) outbreaks. In the present study, an attempt was made to genotype the circulating Newcastle disease virus (NDV) in the backyard and commercial poultry flocks in Assam, India. Sera samples from unvaccinated backyard poultry flocks and tissue samples of ND suspected cases were collected and tested for the presence of NDV antibodies using the Haemagglutination inhibition (HI) test. A total of seven NDV isolates were analyzed from different districts of Assam, India, both genotypically and pathotypically. All isolates were characterized as virulent, carrying 112RRKQRF117 amino acid residues at the cleavage site. As determined by phylogenetic analysis, the isolates clustered with members of genotype XIII of class II NDV. Further analysis of risk factors of ND occurrence was conducted through a questionnaire survey. All the results indicated an occurrence of genotype XIII of NDV in the farms with inadequate biosecurity and farming practices.

Epidemiology of Newcastle disease in poultry in Africa: systematic review and meta-analysis

The present study intended to determine the prevalence of Newcastle disease in unvaccinated backyard poultry in Africa. Using the PRISMA approach, a systematic review and meta-analysis of 107 epidemiological studies was conducted. The meta-analysis identified significant variation of both seroprevalence (I² = 99.38, P = 0.00) and Newcastle disease virus prevalence (I² = 99.52, P = 0.00) reported in various studies included in this review. Publication bias was not detected in either case. Seroprevalence of Newcastle disease was 40.2 (95%CI 32.9-47.8). Seroprevalence was significantly influenced by sampling frame and the African region where the studies were conducted. The prevalence of Newcastle disease virus (NDV) was 12% (95%CI 7.3-17.8), and the variation was influenced by sampling frame, diagnostic test, and regions where the studies were conducted. Also, Newcastle disease (ND) accounted for 33.1% (95%CI 11.9-58.1) of sick chickens. Results also indicated that genotypes VI and VII are widely distributed in all countries included in the study. However, genotype V is restricted in East Africa, and genotypes XIV, XVII, and XVIII are restricted in West and Central Africa. On the other hand, genotype XI occurs in Madagascar only. In addition, virulent genotypes were isolated from apparently healthy and sick birds. It is concluded that several genotypes of NDV are circulating and maintained within the poultry population. African countries should therefore strengthen surveillance systems, be able to study the viruses circulating in their territories, and establish control programs.

Serological evaluation of Newcastle disease protection among broilers at a live bird market in Kano, Northwest Nigeria, and its epidemiological significance

Vaccination is a tool of Newcastle disease (ND) control among broilers. This study aimed at determining the immunity status of sampled broilers against ND at a live bird market in Kano, Northwest Nigeria, and its epidemiological implication. A cross-sectional study of antibodies against Newcastle disease virus (NDV) was carried out among broiler chicken in a live bird market in Kano State, Northwest Nigeria. A total of 471 samples was tested successfully. NDV antibody titer was assayed using hemagglutination-inhibition test (HI) and ND indirect enzyme-linked immunosorbent assay (ELISA). Serological levels of NDV antibodies were 67.9% (ELISA) and 78.1% (HI). Also, 67 (20.9%) samples tested positive for ELISA but negative for HI, whereas 115 (31.3%) samples tested negative for ELISA but positive for HI. There is strong association between the immune status obtained from both tests (P < .05), significant difference exists between the immune titer obtained from both tests (P < .05). Protective antibody titer among the test subjects suggests individual protection against virulent NDV (vNDV) strain; however, protective levels ≥85% that confers herd immunity were not attained. This report emphasizes the need for farmers to be more compliant to ND vaccination schedule and best practices in their poultry farm to enhance ND control in Live Bird Markets (LBMs).

Immunological effect of Moringa Oleifera leaf extract on vaccinated and non-vaccinated Hubbard chickens experimentally infected with Newcastle virus

In veterinary medicine plant based medicine is achieving a huge importance worldwide. This research was subjected to rectify the hydrophilic Moringa Oleifera alcoholic leaves extract could improve the immune system in vaccinated and non-vaccinated broiler Hubbard chickens experimentally exposed to Newcastle disease (ND) virus. Seventy five chicks with age one day old were splitted randomly into five groups equally in distribution with fifteen chick in each group. Group I was untreated unvaccinated (control negative group) while group IV was infected group with NDV (control positive group). The experimental Groups II and V were given daily oral treatment of hydrophilic alcoholic leaves extract of M. oleifera at 200 mg/kg body weight until day 21 of age while groups III and V were ND vaccinated with La Sota strain of ND vaccines. The four groups (II, III, IV, V) were infected with ND virus velogenic strain (VNDV) on day 21. Following to infection, Monitoring of birds were done daily for clinical signs, postmortem examination, morbidity and mortality. Cellular, humeral immune response and phagocytic activity were evaluated and the data were statistically analyzed using (SPSS). Total and differential cell numbers as well as Haemagglutination inhibition (HI) titre increased in the extract treated and vaccinated group which give total protection against NDV much more than treated and unvaccinated group. As a result it could be recommended to use M. Olifera extract from the first day of rearing in Hubbard chicken with ND vaccination program as a prophylactic treatment in protection of birds against ND infection.

Single-Dose Vaccination of Recombinant Chimeric Newcastle Disease Virus (NDV) LaSota Vaccine Strain Expressing Infectious Bursal Disease Virus (IBDV) VP2 Gene Provides Full Protection against Genotype VII NDV and IBDV Challenge

Newcastle disease virus (NDV) and infectious bursal disease virus (IBDV) are the two most important and widespread viruses causing huge economic losses in the global poultry industry. Outbreaks of genotype VII NDV and IBDV variants in vaccinated poultry flocks call for genetically matched vaccines. In the present study, a genetic matched chimeric NDV LaSota vaccine strain expressing VP2 gene of IBDV variant, rLaS-VIIF/HN-VP2 was generated for the first time, in which both the F and HN genes of LaSota were replaced with those of the genotype VII NDV strain FJSW. The cleavage site of the FJSW strain F protein in the rLaS-VIIF/HN-VP2 genome was mutated to the avirulent motif found in LaSota. Expression of IBDV VP2 protein was confirmed by western blot. The rLaS-VIIF/HN-VP2 maintained the efficient replication ability in embryonated eggs, low pathogenicity and genetic stability comparable to that of parental LaSota virus. One dose oculonasal vaccination of one-week-old SPF chickens with rLaS-VIIF/HN-VP2 induced full protection against genotype VII NDV and IBDV lethal challenge. These results indicate that the rLaS-VIIF/HN-VP2 is a promising bivalent vaccine to prevent infections of IBDV and genotype VII NDV.

Molecular evaluation and genetic characterisation of Newcastle disease virus's haemagglutinin-neuraminidase protein isolated from broiler chickens in Iran

Background

Newcastle disease (ND) virus (NDV) is one of the major pathogens in poultry farms that causes severe economic damages to the poultry industry, especially broiler chicken and turkey farms. Despite the endemicity of ND and its many epidemics in the country, the nature of the Iranian strain of the Newcastle virus is still largely unknown. This study aimed to characterise and evaluate NDV isolates obtained from commercial poultry farms in Iran in 2019 through haemagglutinin‐neuraminidase (HN) gene sequencing.

Method

HN gene of each NDV isolate was amplified and sequenced using specific primers followed by phylogenetic analysis of full length of HN gene open reading frame and amino acid (aa) sequence of HN.

Results

Phylogenetic analysis of the HN gene showed that the virus is very closely related to genotypes VII and III. Analysis of HN gene nucleotide sequences showed that all isolates encode proteins with a length of 571 aa.

Conclusion

Results of the present study are useful for a better understanding of molecular epidemiology of indigenous NDV strains and determining important molecular differences between fields and commonly used vaccine strains related to main immunogenic proteins.

Evaluating Disease Threats to Sustainable Poultry Production in Africa: Newcastle Disease, Infectious Bursal Disease, and Avian Infectious Bronchitis in Commercial Poultry Flocks in Kano and Oyo States, Nigeria

The growth of the poultry industry in Nigeria is constrained by major poultry diseases, despite the implementation of vaccination programs. This study aimed to assess the level of protection against Newcastle disease (ND), infectious bursal disease (IBD), and avian infectious bronchitis (IB) afforded by current vaccination schedules and characterize the circulating virus strains in commercial poultry flocks in Nigeria. A cross-sectional study was conducted on 44 commercial poultry farms in Oyo and Kano states of Nigeria. Serum and tissue samples and data on flock, clinical and vaccination records were collected on each farm. Farms were classified as being protected or not protected against ND, IBD and IB based on a defined criterion. Real-time reverse transcription polymerase chain reaction (rRT-PCR) testing was performed for each target virus on tissue samples and positive samples were sequenced. A total of 15/44 (34.1%), 35/44 (79.5%), and 1/44 (2.3%) farms were considered to be protected against ND, IBD, and IB, respectively, at the time of sampling. NDV RNA was detected on 7/44 (15.9%) farms and sequences obtained from 3/7 farms were characterized as the lentogenic strain. Infectious bursal disease virus (IBDV) RNA was detected on 16/44 (36.4%) farms tested; very virulent (vv) IBDV and non-virulent (nv) IBDV strains were both detected in 3/16 (18.8%) positive samples. Sequences of IBDV isolates were either clustered with a group of genotype 3 virulent IBDV strains or were related to vaccine strains MB and D78 strains. IBV RNA was detected on 36/44 (81.8%) farms, with variant02, Massachusetts, 4/91, and Q1 variants detected. Sequences of IBV isolates were either clustered with the vaccines strains Massachusetts M41 and H120 or were most closely related to the D274-like strains or a clade of sequences reported in Nigeria and Niger in 2006 and 2007. This study revealed that most study farms in Oyo and Kano states did not have adequate protective antibody titers against IBV and NDV and were therefore at risk of field challenge. Infectious bursal disease virus and IBV RNA were detected on farms with a history of vaccination suggesting potential vaccination failure, or that the vaccine strains used mismatch with the circulating strains and are therefore not protective.

Epidemiology of Newcastle disease in Africa with emphasis on Côte d'Ivoire: A review

For decades, Newcastle disease (ND) has long been recognized as a frontline viral disease that constrains poultry production throughout Africa. The need to update on the epidemiology of the disease is rife, due to the increasing importance of poultry farming. In addition, poultry farming serves as the top animal food source globally. However, in Africa, the greater population of poultry is reared under traditional and conventional husbandry methods. This hugely impedes the ability of management practices to be correctly embraced in limiting or excluding viral pathogens in the poultry production chain. We conducted this review to consolidate recently published studies in the field and provide an overview of the disease. We reviewed original studies conducted on ND, the current taxonomic classification of the virus, clinical signs of the disease, and laboratory diagnostic methods available for virus detection and typing. This review additionally examined the control methods currently used, including available or circulating vaccines, vaccinations, recent vaccine findings, and the main variants of the virus present in West Africa. More specifically, we present a review of the current status and available information on the disease in Côte d’Ivoire. The lack of up-to-date and relevant information on the current prevalence, socio-economic impact, and ethnoveterinary medicine used against ND is probably the main limitation for appropriate and effective decision-making for better control of this disease in Côte d’Ivoire.

Transboundary Animal Diseases, an Overview of 17 Diseases with Potential for Global Spread and Serious Consequences

Animals provide food and other critical resources to most of the global population. As such, diseases of animals can cause dire consequences, especially disease with high rates of morbidity or mortality. Transboundary animal diseases (TADs) are highly contagious or transmissible, epidemic diseases, with the potential to spread rapidly across the globe and the potential to cause substantial socioeconomic and public health consequences. Transboundary animal diseases can threaten the global food supply, reduce the availability of non-food animal products, or cause the loss of human productivity or life. Further, TADs result in socioeconomic consequences from costs of control or preventative measures, and from trade restrictions. A greater understanding of the transmission, spread, and pathogenesis of these diseases is required. Further work is also needed to improve the efficacy and cost of both diagnostics and vaccines. This review aims to give a broad overview of 17 TADs, providing researchers and veterinarians with a current, succinct resource of salient details regarding these significant diseases. For each disease, we provide a synopsis of the disease and its status, species and geographic areas affected, a summary of in vitro or in vivo research models, and when available, information regarding prevention or treatment.

Discriminant analysis of response to Newcastle disease and heat tolerance among chicken genotypes in hot humid tropical environment

Newcastle disease and heat stress reduce the productivity of local chickens of Nigeria (LCN). This study compared the antibody response to Newcastle disease and heat tolerance among different LCN genotypes in hot humid tropics using multivariate discriminant analysis. A total of 299 birds were used for the study. Geometric mean titre against Newcastle disease before vaccination (GMTB), geometric mean titre against Newcastle disease after vaccination (GMTA), rectal temperature at week 4 (RT4), pulse rate at week 4 (PR4), respiratory rate at week 4 (RR4), heat stress index at week 4 (H4), rectal temperature at week 13 (RT13), pulse rate at week 13 (PR13), respiratory rate at week 13 (RR13) and heat stress index at week 13 (H13) were measured. All the traits were significantly (p < 0.05) affected by the genotype while sex differences were only observed in GMTB, GMTA and RR13. The stepwise discriminant analysis revealed RR4, PR13, RT13, H4, GMTA, GMTB, H13 and RT4 to be effective in differentiating the three chicken genotypes. Two canonical variables that accounted for 60.21% and 39.79% of the total variation were revealed. Linear discriminant functions for differentiation of the three chicken genotypes were also developed. 87.39% of normal feather, 76.58% of naked neck and 100% of frizzle feather chickens were correctly assigned into their genotypes. The longest Mahalanobis distance was observed between normal feather and frizzle feather chickens. The discriminant functions developed in this study could be used to differentiate the three genotypes of LCN using antibody response to Newcastle disease and heat tolerance.

Molecular Characterization of Velogenic Newcastle Disease Virus (Sub-Genotype VII.1.1) from Wild Birds, with Assessment of Its Pathogenicity in Susceptible Chickens

Simple Summary

Newcastle disease virus (NDV) is a highly contagious viral disease affecting a wide range of avian species. The disease can be particularly virulent in chickens, resulting in high mortality and morbidity. In this study, we characterized velogenic NDV sub-genotype VII.1.1 from wild birds and assessed its pathogenicity in susceptible chickens. One hundred wild birds from the vicinity of poultry farms with a history of NDV infection were examined clinically. Pooled samples from the spleen, lung, and brain were screened using real-time reverse transcriptase polymerase chain reaction (RRT-PCR) and reverse transcriptase polymerase chain reaction (RT-PCR) to detect the NDV F gene fragment, and phylogenetic analysis was carried out for identification of the genetic relatedness of the virus. Chickens were infected with the strains identified, and the major histopathological changes were assessed. Interestingly, NDV was detected in 44% of cattle egret samples and 26% of house sparrow samples by RRT-PCR, while RT-PCR detected NDV in 36% of cattle egrets examined and 20% of house sparrow samples. Phylogenetic analysis revealed close identity, of 99.7–98.5% (0.3–1.5% pairwise distance), between the isolates used in our study and other Egyptian class II, sub-genotype VII.1.1 NDV strains. Histopathological examination identified marked histopathological changes that are consistent with NDV. These findings provide interesting data in relation to the detection of NDV sub-genotype VII.1.1 in wild birds and reveal the major advantages of the combined use of molecular and histopathological methods in the detection and characterization of the virus. More research is needed to determine the characteristics of this contagious disease in the Egyptian environment.

Abstract

Newcastle disease (ND) is considered to be one of the most economically significant avian viral diseases. It has a worldwide distribution and a continuous diversity of genotypes. Despite its limited zoonotic potential, Newcastle disease virus (NDV) outbreaks in Egypt occur frequently and result in serious economic losses in the poultry industry. In this study, we investigated and characterized NDV in wild cattle egrets and house sparrows. Fifty cattle egrets and fifty house sparrows were collected from the vicinity of chicken farms in Kafrelsheikh Governorate, Egypt, which has a history of NDV infection. Lung, spleen, and brain tissue samples were pooled from each bird and screened for NDV by real-time reverse transcriptase polymerase chain reaction (RRT-PCR) and reverse transcriptase polymerase chain reaction (RT-PCR) to amplify the 370 bp NDV F gene fragment. NDV was detected by RRT-PCR in 22 of 50 (44%) cattle egrets and 13 of 50 (26%) house sparrows, while the conventional RT-PCR detected NDV in 18 of 50 (36%) cattle egrets and 10 of 50 (20%) of house sparrows. Phylogenic analysis revealed that the NDV strains identified in the present study are closely related to other Egyptian class II, sub-genotype VII.1.1 NDV strains from GenBank, having 99.7–98.5% identity. The pathogenicity of the wild-bird-origin NDV sub-genotype VII.1.1 NDV strains were assessed by experimental inoculation of identified strains (KFS-Motobas-2, KFS-Elhamoul-1, and KFS-Elhamoul-3) in 28-day-old specific-pathogen-free (SPF) Cobb chickens. The clinical signs and post-mortem changes of velogenic NDV genotype VII (GVII) were observed in inoculated chickens 3 to 7 days post-inoculation, with 67.5–70% mortality rates. NDV was detected in all NDV-inoculated chickens by RRT-PCR and RT-PCR at 3, 7, and 10 days post-inoculation. The histopathological findings of the experimentally infected chickens showed marked pulmonary congestion and pneumonia associated with complete bronchial stenosis. The spleen showed histocytic cell proliferation with marked lymphoid depletion, while the brain had malacia and diffuse gliosis. These findings provide interesting data about the characterization of NDV in wild birds from Egypt and add to our understanding of their possible role in the transmission dynamics of the disease in Egypt. Further research is needed to explore the role of other species of wild birds in the epidemiology of this disease and to compare the strains circulating in wild birds with those found in poultry.

Phylogenetic relationship and genotype variation of six Newcastle disease viruses isolated from duck in Indonesia

Background and Aim:

Newcastle disease viruses (NDVs) are frequently acquired from all ages and types of bird species. In general, ducks are considered as potential reservoirs for different genotypes of NDV and are resistant even to velogenic NDV strains. This research was conducted to genotypically and phylogenetically characterize NDV isolates collected from unvaccinated ducks from Indonesia.

Materials and Methods:

A total of 200 samples were collected through cloacal swabs and were inoculated in the allantoic sacs of 8-day-old specific pathogen-free eggs. Hemagglutination (HA) activity was analyzed through a HA test, and isolated viruses were characterized by reverse transcription-polymerase chain reaction targeting the complete fusion (F)-gene of NDV using three primer sets. One primer set was specific for the F protein cleavage site sequences of velogenic, mesogenic, and lentogenic NDV strains.

Results:

The results demonstrated that three isolates (NDV/Duck/B104/19, NDV/Duck/B125/19, and NDV/Duck/BK43/19) belonged to genotype VII and one (NDV/Duck/TD19/19) to genotype VI. Other isolates (NDV/Duck/A74/19 and NDV/Duck/M147/19) belonged to genotype II Class II. Based on the F protein cleavage site and the pathogenicity tests, two isolates (NDV/Duck/B104/19 and NDV/Duck/B125/19) were categorized as velogenic viruses and four (NDV/Duck/BK43/19, NDV/Duck/TD19/19, NDV/Duck/A74/19, and NDV/Duck/M147/19) as lentogenic viruses.

Conclusion:

The results indicate that NDVs from unvaccinated ducks from Indonesia carry various genotypes and pathotypes of NDVs; therefore, these viruses are still circulating in the environment and might pose a risk of Newcastle disease outbreak.

Lithium chloride functions as Newcastle disease virus-induced ER-stress modulator and confers anti-viral effect

Newcastle disease is a severe clinical manifestation of avian species caused by Newcastle disease virus (NDV). Although several vaccination strategies are available to protect poultry against NDV infection, even then, outbreaks have been reported in the vaccinated birds. The lack of therapeutics against NDV makes the need for effective anti-viral drugs is of utmost importance. Lithium Chloride (LiCl) is a widely prescribed drug for the treatment of bipolar disorder, acute brain injuries, and chronic neurodegenerative diseases. Also, LiCl has been repurposed as an effective anti-viral drug for some viral infections. In the present work, we have investigated the efficacy of LiCl to inhibit NDV replication using in vitro, in ovo, and in vivo models. Our results collectively showed the modulation of NDV replication after the LiCl treatment. We also demonstrated that NDV induces endoplasmic reticulum stress (ER-stress), and a stress-inducible ER chaperone, glucose-regulating protein 78 (GRP78), was found to be over-expressed after NDV infection. Subsequently, the treatment of NDV infected cells with LiCl significantly reduced the transcript and protein levels of GRP78. Finally, we concluded that LiCl treatment protects the cells from ER-stress induced by the NDV infection.

Protective efficacy of inactivated Newcastle disease virus vaccines prepared in two different oil-based adjuvants

Despite the availability of Newcastle disease (ND) vaccines for more than six decades, disease outbreaks continue to occur with huge economic consequences to the global poultry industry. The aim of this study is to develop a safe and effective inactivated vaccine based on a recently isolated Newcastle disease virus (NDV) strain IBS025/13 and evaluate its protective efficacy in chicken following challenge with a highly virulent genotype VII isolate. Firstly, high titre of IBS025/13 was exposed to various concentrations of binary ethylenimine (BEI) to determine the optimal conditions for complete inactivation of the virus. The inactivated virus was then prepared in form of a stable water-in-oil emulsion of black seed oil (BSO) or Freund’s incomplete adjuvant (FIA) and used as vaccines in specific pathogen-free chicken. Efficacy of various vaccine preparations was also evaluated based on the ability of the vaccine to protect against clinical disease, mortality and virus shedding following challenge with highly virulent genotype\VII NDV isolate. The results indicate that exposure of NDV IBS025/13 to 10 mM of BEI for 21 h at 37 °C could completely inactivate the virus without tempering with the structural integrity of the viral hemagglutin-neuraminidase protein. More so, the inactivated vaccines adjuvanted with either BSO- or FIA-induced high hemagglutination inhibition antibody titre that protected the vaccinated birds against clinical disease and in some cases virus shedding, especially when used together with live attenuated vaccines. Thus, genotype VII-based NDV-inactivated vaccines formulated in BSO could substantially improve poultry disease control particularly when combined with live attenuated vaccines.

Development of an Effective and Stable Genotype-Matched Live Attenuated Newcastle Disease Virus Vaccine Based on a Novel Naturally Recombinant Malaysian Isolate Using Reverse Genetics

Genotype VII Newcastle disease viruses are associated with huge economic losses in the global poultry industry. Despite the intensive applications of vaccines, disease outbreaks caused by those viruses continue to occur frequently even among the vaccinated poultry farms. An important factor in the suboptimal protective efficacy of the current vaccines is the genetic mismatch between the prevalent strains and the vaccine strains. Therefore, in the present study, an effective and stable genotype-matched live attenuated Newcastle disease virus (NDV) vaccine was developed using reverse genetics, based on a recently isolated virulent naturally recombinant NDV IBS025/13 Malaysian strain. First of all, the sequence encoding the fusion protein (F) cleavage site of the virus was modified in silico from virulent polybasic (RRQKRF) to avirulent monobasic (GRQGRL) motif. The entire modified sequence was then chemically synthesized and inserted into pOLTV5 transcription vector for virus rescue. A recombinant virus termed mIBS025 was successfully recovered and shown to be highly attenuated based on OIE recommended pathogenicity assessment indices. Furthermore, the virus was shown to remain stably attenuated and retain the avirulent monobasic F cleavage site after 15 consecutive passages in specific-pathogen-free embryonated eggs and 12 passages in one-day-old chicks. More so, the recombinant virus induced a significantly higher hemagglutination inhibition antibody titre than LaSota although both vaccines fully protected chicken against genotype VII NDV induced mortality and morbidity. Finally, mIBS025 was shown to significantly reduce both the duration and quantity of cloacal and oropharyngeal shedding of the challenged genotype VII virus compared to the LaSota vaccine. These findings collectively indicate that mIBS025 provides a better protective efficacy than LaSota and therefore can be used as a promising vaccine candidate against genotype VII NDV strains.

Exploring the Prospects of Engineered Newcastle Disease Virus in Modern Vaccinology

Many traditional vaccines have proven to be incapable of controlling newly emerging infectious diseases. They have also achieved limited success in the fight against a variety of human cancers. Thus, innovative vaccine strategies are highly needed to overcome the global burden of these diseases. Advances in molecular biology and reverse genetics have completely restructured the concept of vaccinology, leading to the emergence of state-of-the-art technologies for vaccine design, development and delivery. Among these modern vaccine technologies are the recombinant viral vectored vaccines, which are known for their incredible specificity in antigen delivery as well as the induction of robust immune responses in the vaccinated hosts. Although a number of viruses have been used as vaccine vectors, genetically engineered Newcastle disease virus (NDV) possesses some useful attributes that make it a preferable candidate for vectoring vaccine antigens. Here, we review the molecular biology of NDV and discuss the reverse genetics approaches used to engineer the virus into an efficient vaccine vector. We then discuss the prospects of the engineered virus as an efficient vehicle of vaccines against cancer and several infectious diseases of man and animals.

Molecular and biological characterization of some circulating strains of Newcastle disease virus in broiler chickens from Eastern Saudi Arabia in 2012-2014

Background and Aim:

Newcastle disease (ND) is a worldwide poultry disease that is historically known to cause severe losses in the poultry industry. In the present study, attempts were made to characterize ND virus (NDV) recovered from broiler chickens in the Eastern Region of Saudi Arabia from January 2012 to March 2014.

Materials and Methods:

Reverse transcription-polymerase chain reaction was used for the detection of NDV followed by partial sequencing of the fusion (F) gene. The intracerebral pathogenicity index (ICPI), mean death time (MDT), and complete sequencing of the hemagglutinin-neuraminidase (HN) gene were also used for further biological and molecular characterization.

Results:

NDV was detected at a rate of 9.6% (11/115) of the tested flocks, most of which were vaccinated against ND. F gene-based phylogeny and motifs of the fusion protein cleavage site (FPCS) showed segregation of Saudi isolates into two groups. The first group contained 10 isolates and was located in genotype II with the lentogenic motif ¹¹²GRQGRL¹¹⁷ at the FPCS. The second group contained one isolate and was located in genotype VII with velogenic motif ¹¹²RRQKRF¹¹⁷. Further characterization using the ICPI and MDT of two representative isolates showed virulence of both tested isolates. Phylogenetic analysis of the HN gene showed close nucleotide identity between the two isolates. A BLAST search for sequences similar to HN gene sequences showed high identity with isolates from the surrounding region.

Conclusion:

The present findings showed a low detection rate of NDV, possibly due to the wide application of vaccines, and the circulation of at least two NDV genotypes, II and VII, in the Eastern Region of Saudi Arabia. The present Saudi isolates may share common ancestors with isolates from the surrounding region.

First Isolation and Rapid Identification of Newcastle Disease Virus from Aborted Fetus of Dromedary Camel Using Next-Generation Sequencing

Newcastle disease virus (NDV) causes morbidities and mortalities in wild and domestic birds globally. For humans, exposure to infected birds can cause conjunctivitis and influenza-like symptoms. NDV infections in mammals are rarely reported. In this study, using next-generation sequencing, an NDV was identified and isolated from Vero cells inoculated with the nasal swab of an aborted dromedary fetus in Dubai, during the time when an NDV outbreak occurred in a pigeon farm located in close proximity to the dairy camel farm where the mother of the aborted dromedary fetus resided, and there were a lot of pigeons in the camel farm. Genome analysis revealed that the structurally and functionally important features of other NDVs were also present in this dromedary NDV genome. Phylogenetic analysis based on the nucleotide sequences of fusion protein (F), hemagglutinin-neuraminidase protein (HN) and complete polyprotein showed that the virus belonged to sub-genotype VIg of class II NDV and is most closely related to pigeon NDVs in Egypt in the same year. The present study is the first that demonstrated isolation of NDV in dromedaries. Further study is warranted to investigate the relationship between NDV infection and abortion.

Genomic comparison of Newcastle disease viruses isolated in Nigeria between 2002 and 2015 reveals circulation of highly diverse genotypes and spillover into wild birds

Newcastle disease virus (NDV) has a wide avian host range and a high degree of genetic variability, and virulent strains cause Newcastle disease (ND), a worldwide concern for poultry health. Although NDV has been studied in Nigeria, genetic information about the viruses involved in the endemicity of the disease and the transmission that likely occurs at the poultry-wildlife interface is still largely incomplete. Next-generation and Sanger sequencing was performed to provide complete (n = 73) and partial genomic sequence data (n = 38) for NDV isolates collected from domestic and wild birds in Nigeria during 2002-2015, including the first complete genome sequences of genotype IV and subgenotype VIh from the African continent. Phylogenetic analysis revealed that viruses of seven different genotypes circulated in that period, demonstrating high genetic diversity of NDV for a single country. In addition, a high degree of similarity between NDV isolates from domestic and wild birds was observed, suggesting that spillovers had occurred, including to three species that had not previously been shown to be susceptible to NDV infection. Furthermore, the first spillover of a mesogenic Komarov vaccine virus is documented, suggesting a previous spillover and evolution of this virus. The similarities between viruses from poultry and multiple bird species and the lack of evidence for host adaptation in codon usage suggest that transmission of NDV between poultry and non-poultry birds occurred recently. This is especially significant when considering that some viruses were isolated from species of conservation concern. The high diversity of NDV observed in both domestic and wild birds in Nigeria emphasizes the need for active surveillance and epidemiology of NDV in all bird species.