The emergence of new virulent genotypes and the continued genetic drift of Newcastle disease virus (NDV) implies that distinct genotypes of NDV are simultaneously evolving in different geographic locations across the globe, including throughout Africa, where NDV is an important veterinary pathogen. Expanding the genomic diversity of NDV increases the possibility of diagnostic and vaccine failures. In this review, we systematically analyzed the genetic diversity of NDV genotypes in Africa using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Information published between 1999 and 2022 were used to obtain the genetic background of different genotypes of NDV and their geographic distributions in Africa. The following genotypes were reported in Africa: I, II, III, IV, V, VI, VII, VIII, XI, XIII, XIV, XVII, XVIII, XX, and XXI. A new putative genotype has been detected in the Democratic Republic of the Congo. However, of 54 African countries, only 26 countries regularly report information on NDV outbreaks, suggesting that this number may be vastly underestimated. With eight different genotypes, Nigeria is the country with the greatest genotypic diversity of NDV among African countries. Genotype VII is the most prevalent group of NDV in Africa, which was reported in 15 countries. A phylogeographic analysis of NDV sequences revealed transboundary transmission of the virus in Eastern Africa, Western and Central Africa, and in Southern Africa. A regional and continental collaboration is recommended for improved NDV risk management in Africa.

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.

Newcastle disease virus (NDV) is an extremely contagious and deadly virus that affects numerous bird species, posing serious threats to poultry production on a global scale. In addition to implementing biosecurity practices in farming systems, vaccination remains the most effective means of controlling Newcastle disease (ND). However, while existing commercial vaccines provide some level of protection, the effectiveness of these vaccines can be questionable, particularly in field settings where the complexity of vaccination program implementation poses significant challenges, especially against virulent genotypes of NDV. A genotype-matched NDV DNA vaccine could potentially offer a more effective vaccination approach than currently available live attenuated vaccines. By being specifically tailored to match circulating strains, such a vaccine might improve efficacy and reduce the risk of vaccine failure due to genotype mismatch. To develop an alternative vaccine approach, two ND DNA vaccines were constructed in this study. Each vaccine developed in this study contains the fusion (F) and haemagglutinin-neuraminidase (HN) genes of a virulent NDV genotype VII isolate from Tanzania. Interferon lambda-3 (IFNλ3; IL-28b), which has demonstrated capacity to significantly enhance specific adaptive immune responses and decreased levels of inflammatory cytokines, as well as improved protective responses at a high viral challenge dose, was included in one of the developed vaccines. These plasmids were designated pTwist-F-HN-VII-IL28b and pTwist-F-HN-VII. The two plasmids differed in that pTwist-F-HN-VII-IL28b contained the cytokine adjuvant IL-28b. Transfection of cells and subsequent immunofluorescence assays indicated that both plasmids expressed high levels of NDV F-HN proteins. In vivo immunization demonstrated that chicks intramuscularly immunized with pTwist-F-HN-VII-IL28b exhibited significant immune responses compared to chicks immunized with pTwist-F-HN-VII or the commonly used LaSota vaccine (LaSota), which was used as a control. The protective efficacy of pTwist-F-HN-VII-IL28b was 80% after challenge with the highly virulent NDV strain ON148423, compared to 60% for chicks vaccinated using LaSota, and pTwist-F-HN-VII. The findings of this study indicate that IL-28b can be employed as a molecular adjuvant for NDV vaccines. This study represents a key milestone in Newcastle disease vaccine research, particularly in the development of a genotype-matched DNA vaccine candidate. Additionally, this study demonstrated that the combination of F, HN, and IL-28b elicits an efficacious immune response against virulent NDV strains.

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.

Background: Newcastle disease (ND) is a viral disease affecting a wide range of bird species and has a considerable financial impact on the world's poultry market. The ND virus (NDV) strains currently circulating in poultry throughout Africa, and especially in East Africa, exhibit significant genetic variation.Objectives: The primary objective of the present investigation was to investigate the NDV genotypes in chickens raised in backyards in Tanzania's Morogoro and Iringa districts, which were associated with ND outbreaks.Methods: Two tissue samples from chickens taken during a suspected ND outbreak in Tanzania's Morogoro (Eastern zone) and Iringa (Southern highlands zone) were subjected to reverse transcription polymerase chain reaction targeting the fusion (F) and hemagglutinin-neuraminidase (HN) genes, followed by sequencing.Results: Based on comprehensive analysis of the entire F and HN gene sequences, the viruses were categorized as genotype VII and displayed significant genetic similarity with NDV strains previously identified in Mozambique, South Africa, Zambia, Zimbabwe, Botswana, Southeast Asia, and China. The uniformity in the amino acid cleavage site motif of the F protein across the examined NDV isolates, characterized by 112R–R–Q/K–K–R–F117, indicates their classification as virulent strains.Conclusion: Regularly characterizing circulating strains and expanding the study to other parts of Tanzania may help to enhance disease control by giving a more precise picture of the situation regarding ND, especially in light of the issues posed by NDV genotype VII elsewhere.

Newcastle disease virus (NDV) remains one of the most economically devastating pathogens affecting poultry production. Despite decades of vaccination efforts, NDV continues to circulate and remain endemic across Asia, Africa, and the Middle East, posing persistent threats to food security, rural livelihoods, and international trade. This review comprehensively examines the current landscape of NDV vaccine platforms, their immunological mechanisms, and the multifaceted challenges limiting their efficacy. We critically evaluated conventional platforms, including lentogenic live attenuated vaccines and oil-adjuvanted inactivated formulations, highlighting their contributions to disease control while addressing their inherent limitations including cold-chain dependence, maternal antibody interference, incomplete cross-protection against heterologous genotypes, and the absence of differentiating infected from vaccinated animals (DIVA) capability. We then examined next-generation approaches, including recombinant vector platforms, virus-like particles, DNA and mRNA vaccines, and AI/ML-informed antigen design, assessing each against its actual stage of development, from vaccines already in commercial use to platforms that remain preclinical or theoretical, rather than treating design capability as equivalent to field-ready deployment. Finally, we addressed regulatory, manufacturing, and logistical barriers to vaccine deployment in low-resource settings, including a dedicated feasibility assessment and platform-comparison table for smallholder-dominated, endemic regions. Integrating these technological advances with robust surveillance, biosecurity, and supportive policies will be essential for achieving sustainable NDV control and advancing toward eradication.