Cocirculation of Newcastle Disease Virus Genotypes XII and VII Along with Nonvirulent Forms Characterized in Domestic Birds from Peru.

Newcastle disease virus (NDV) is one of the most important pathogens affecting poultry, given its impact on health and production systems worldwide, despite widespread vaccination. Over the past 20 years, NDV has caused severe outbreaks of disease in Peru. These outbreaks primarily affected gamecocks and broiler chickens, with an additional reported case in commercial layers. Therefore, our objective was to identify and characterize the virus responsible for these cases in Peru. We analyzed 14 suspected clinical cases in domestic birds for NDV detection, isolation, and genetic characterization. Among these cases, seven involved gamecocks, with six genotype XII isolates and one genotype VII isolate, representing the first report of NDV genotype VII isolate from fighting roosters in Peru. Additionally, among the six cases in broiler chickens, we detected four genotype XII isolates and three genotype II isolates, including one sample containing both genotypes XII and II. Furthermore, a genotype I viral isolate was identified in a laying hen. Hence, we concluded that two divergent, highly virulent NDV genotypes, genotypes XII and VII, along with avirulent forms such as genotypes I and II are circulating among domestic birds in Peru. Genetic analysis indicates that these viruses are evolving locally within avian species and offers the basis necessary for vaccine adaptation to circulating viruses. Our results highlight the cocirculation of multiple virulent and nonvirulent NDV genotypes in domestic birds in Peru, underscoring the potential role of gamecocks as a viral source of virulent NDV strains in the country and the occurrence of outbreaks in poultry farms.

Cocirculación de los genotipos XII y VII del virus de la enfermedad de Newcastle junto con formas no virulentas caracterizadas en aves domésticas del Perú. El virus de la enfermedad de Newcastle (NDV) es uno de los patógenos más importantes que afectan a la avicultura, dado su impacto en la salud y los sistemas de producción en todo el mundo, a pesar de la vacunación generalizada. Durante los últimos 20 años, el virus de la enfermedad de Newcastle ha causado graves brotes de enfermedades en el Perú. Estos brotes afectaron principalmente a gallos de pelea y pollos de engorde, con un caso adicional reportado en aves de postura comerciales. Por lo tanto, nuestro objetivo fue identificar y caracterizar el virus responsable de estos casos en el Perú. Se analizaron 14 casos cl'inicos sospechosos en aves domésticas para la detección, aislamiento y caracterización genética del virus de Newcastle. Entre estos casos, siete involucraron gallos de pelea, con seis aislamientos del genotipo XII y un aislado del genotipo VII, lo que representa el primer informe de aislamiento del genotipo VII del virus de Newcastle de gallos de pelea en Perú. Además, entre los seis casos en pollos de engorde, se detectaron cuatro aislados del genotipo XII y tres aislados del genotipo II, incluida una muestra que con-ten'ia ambos genotipos XII y II. Además, se identificó un aislado viral de genotipo I en una gallina de postura. Por lo tanto, se concluye que dos genotipos divergentes y altamente virulentos del virus de Newcastle, los genotipos XII y VII, junto con formas avirulentas como los genotipos I y II, están circulando entre las aves domésticas en el Perú. El análisis genético indica que estos virus están evolucionando localmente dentro de las especies aviares y ofrece las bases necesarias para realizar adaptaciones de las vacunas contra los virus circulantes. Nuestros resultados resaltan la cocirculación de múltiples genotipos del virus de Newcastle virulentos y no virulentos en aves domésticas en Perú, subrayando el papel potencial de los gallos de pelea como fuente viral de cepas virulentas del virus de Newcastle en el pa'is y la aparición de brotes en granjas av'icolas.

Phylogenetic analysis, genetic diversity, and epidemiology of pigeon paramyxovirus type 1 in China.

Pigeon paramyxovirus type 1 (PPMV-1) poses significant economic challenges to the pigeon industry in China. However, information about the prevalence, genetic diversity, and epidemiology of PPMV-1 in China is still lacking. In this study, we isolated six strains of PPMV-1 from Hubei and Zhejiang provinces in 2022. All six isolates were found to belong to subgenotype VI.2.1.1.2.2. Five of them were identified as mesogenic and one as lentogenic. Multiple mutations were observed in the F and HN proteins of these isolates. Comprehensive analysis of global PPMV-1 strains highlighted the dominance of genotype VI, showing that VI.2.1.1.2.2 has been the dominant subgenotype since 2011. We also identified 36 host-specific amino acid substitutions that are unique to PPMV-1 in comparison to chicken-origin NDVs. The data reported here contribute to our understanding of the epidemiology, genetic diversity, and prevalence of PPMV-1 and serve as a valuable reference for the prevention and control of PPMV-1.

Genomic Diversity and Evolutionary Insights of Avian Paramyxovirus-1 in Avian Populations in Pakistan.

The virulent form of Avian paramyxovirus-1 (APMV-1), commonly known as Newcastle Disease Virus (NDV), is a pathogen with global implications for avian health, affecting both wild and domestic bird populations. In Pakistan, recurrent Newcastle Disease (caused by NDV) outbreaks have posed significant challenges to the poultry industry. Extensive surveillance in Pakistan over 20 years has demonstrated a dynamic genetic diversity among circulating APMV-1 strains, emphasizing the potential necessity for customized vaccination strategies and continuous surveillance. In this study, 13 APMV-1-positive isolates harboring four different APMV-1 genotypes circulating throughout Pakistan were identified. These included the highly virulent genotypes VII and XIII, genotype XXI, commonly associated with Columbiformes, and genotype II, hypothesized to have been detected following vaccination. These findings underscore the intricate interplay of mutational events and host-immune interactions shaping the evolving NDV landscape. This study advances our understanding of the evolutionary dynamics of APMV-1 in Pakistan, highlighting the need for tailored vaccination strategies and continuous surveillance to enable effective APMV-1 management in avian populations, further emphasizing the importance of globally coordinated strategies to tackle APMV-1, given its profound impact on wild and domestic birds.

Integrative study of chicken lung transcriptome to understand the host immune response during Newcastle disease virus challenge.

Introduction: Newcastle disease is one of the significant issues in the poultry industry, having catastrophic effects worldwide. The lung is one of the essential organs which harbours Bronchus-associated lymphoid tissue and plays a vital role in the immune response. Leghorn and Fayoumi breeds are known to have differences in resistance to Newcastle disease. Along with genes and long non-coding RNAs (lncRNAs) are also known to regulate various biological pathways through gene regulation. Methods: This study analysed the lung transcriptome data and identified the role of genes and long non-coding RNAs in differential immune resistance. The computational pipeline, FHSpipe, as used in our previous studies on analysis of harderian gland and trachea transcriptome was used to identify genes and lncRNAs. This was followed by differential expression analysis, functional annotation of genes and lncRNAs, identification of transcription factors, microRNAs and finally validation using qRT-PCR. Results and discussion: A total of 8219 novel lncRNAs were identified. Of them, 1263 lncRNAs and 281 genes were differentially expressed. About 66 genes were annotated with either an immune-related GO term or pathway, and 12 were annotated with both. In challenge and breed-based analysis, most of these genes were upregulated in Fayoumi compared to Leghorn, and in timepoint-based analysis, Leghorn challenge chicken showed downregulation between time points. A similar trend was observed in the expression of lncRNAs. Co-expression analysis has revealed several lncRNAs co-expressing with immune genes with a positive correlation. Several genes annotated with non-immune pathways, including metabolism, signal transduction, transport of small molecules, extracellular matrix organization, developmental biology and cellular processes, were also impacted. With this, we can understand that Fayoumi chicken showed upregulated immune genes and positive cis-lncRNAs during both the non-challenged and NDV-challenge conditions, even without viral transcripts in the tissue. This finding shows that these immune-annotated genes and coexpressing cis-lncRNAs play a significant role in Fayoumi being comparatively resistant to NDV compared to Leghorn. Our study affirms and expands upon the outcomes of previous studies and highlights the crucial role of lncRNAs during the immune response to NDV. Conclusion: This analysis clearly shows the differences in the gene expression patterns and lncRNA co-expression with the genes between Leghorn and Fayoumi, indicating that the lncRNAs and co-expressing genes might potentially have a role in differentiating these breeds. We hypothesise that these genes and lncRNAs play a vital role in the higher resistance of Fayoumi to NDV than Leghorn. This study can pave the way for future studies to unravel the biological mechanism behind the regulation of immune-related genes.

Isolation and Genetic Characterization of Genotype VII Velogenic Pathotype Newcastle Disease Virus from Commercial Chicken Farms in Central Ethiopia, Distinct from the Local Vaccine Strains.

Newcastle disease (ND) is caused by virulent strains of avian paramyxovirus type 1, also known as Newcastle disease virus (NDV). Despite vaccination, the frequency of reported outbreaks in Ethiopia has increased. From January to June 2022, an active outbreak investigation was conducted in six commercial chicken farms across areas of central Ethiopia to identify the circulating NDV strains. Thirty pooled tissue specimens were collected from chickens suspected of being infected with NDV. A questionnaire survey of farm owners and veterinarians was also carried out to collect information on the farms and the outbreak status. NDV was isolated using specific-pathogen-free (SPF)-embryonated chicken eggs and detected using haemagglutination and the reverse transcriptase-polymerase chain reaction (RT-PCR). The genotype and virulence of field NDV isolates were determined using phylogenetic analysis of fusion (F) protein gene sequences and the mean death time (MDT) test in SPF-embryonated chicken eggs. The questionnaire results revealed that ND caused morbidity (23.1%), mortality (16.3%), case fatality (70.8%), and significant economic losses. Eleven of thirty tissue specimens tested positive for NDV using haemagglutination and RT-PCR. The MDT testing and sequence analysis revealed the presence of virulent NDV classified as genotype VII of class II velogenic pathotype and distinct from locally used vaccine strains (genotype II). The amino acid sequences of the current virulent NDV fusion protein cleavage site motif revealed 112RRQKR↓F117, unlike the locally used avirulent vaccine strains (112GRQGR↓L117). The epidemiological data, MDT results, cleavage site sequence, and phylogenetic analysis all indicated that the present NDV isolates were virulent. The four NDV sequences were deposited in GenBank with accession numbers F gene (PP726912-15) and M gene (PP726916-19). The genetic difference between avirulent vaccine strains and circulating virulent NDV could explain the low level of protection provided by locally used vaccines. Further studies are needed to better understand the circulating NDV genotypes in different production systems.

Arginyltransferase 1 (ATE1)-mediated proteasomal degradation of viral haemagglutinin protein: a unique host defence mechanism.

The extensive protein production in virus-infected cells can disrupt protein homeostasis and activate various proteolytic pathways. These pathways utilize post-translational modifications (PTMs) to drive the ubiquitin-mediated proteasomal degradation of surplus proteins. Protein arginylation is the least explored PTM facilitated by arginyltransferase 1 (ATE1) enzyme. Several studies have provided evidence supporting its importance in multiple physiological processes, including ageing, stress, nerve regeneration, actin formation and embryo development. However, its function in viral pathogenesis is still unexplored. The present work utilizes Newcastle disease virus (NDV) as a model to establish the role of the ATE1 enzyme and its activity in pathogenesis. Our data indicate a rise in levels of N-arginylated cellular proteins in the infected cells. Here, we also explore the haemagglutinin-neuraminidase (HN) protein of NDV as a presumable target for arginylation. The data indicate that the administration of Arg amplifies the arginylation process, resulting in reduced stability of the HN protein. ATE1 enzyme activity inhibition and gene expression knockdown studies were also conducted to analyse modulation in HN protein levels, which further substantiated the findings. Moreover, we also observed Arg addition and probable ubiquitin modification to the HN protein, indicating engagement of the proteasomal degradation machinery. Lastly, we concluded that the enhanced levels of the ATE1 enzyme could transfer the Arg residue to the N-terminus of the HN protein, ultimately driving its proteasomal degradation.

Authorizing of Immunogenicity of Concentrated and Purified Newcastle Disease Virus V4 Strain using Downstream Processing.

Newcastle disease virus (NVD) from the Paramyxoviridae family is a single-stranded negative-sense RNA virus. This infection can affect both domestic poultry and almost all other bird species. It has been considered a very severe difficulty for the poultry industry all over the world. Even though it remains a potential threat to poultry industries, this virus is a powerful oncolytic virus as well. In this study, a process was accomplished to achieve concentrated and highly purified NDV V4 strain particles. Downstream processing of Newcastle virus strain V4 was characterized by amplifying virus in embryonated chicken eggs. Through a sequence of steps, harvesting allantoic fluid, clarification by centrifuge, concentration by ultrafiltration, and size exclusion separation, the reduced volume and pure virus particles were considered for the amount of ovalbumin, hemagglutinin activity, transmission electron microscopy (TEM), electrophoresis, and additionally immunogenicity of prepared antigens. The results presented a high recovery of HA activity in concentrated and purified virus with the removal of ovalbumin and the typical morphology based on TEM. Sepharose CL-4B was determined as the best media among all used resins to purify the virus. Prepared formulations as vaccines demonstrated positive hemagglutinin inhibition for 6 months and stability for 2 years. Strong evidence from organized studies supports the effectiveness of this method in concentrating and purifying intact NDV, which could be valuable in vaccine research, antiserum preparation, or even as an alternative oncotic agent to traditional methods. Despite further studies being conducted, this method can be utilized particularly on a semi-industrial scale to produce various vaccine components.

Genetic evolution of Newcastle Disease Virus sub-genotype VII.2 isolates, diagnosed from vaccinated poultry farms of Gujarat, India.

Newcastle disease was suspected in 37 commercial poultry farms, including 12 layer and 25 broiler farms in four districts of Gujarat, India. Vaccination had been done in 32 (20 broilers and 12 layers) farms. Tissue samples from each farm were pooled as one sample. In egg embryo inoculation, HA-HI and PCR, respectively, 32/37, 29/37, and 24/37 samples were found positive. Pathotyping by mean death time calculation and primer combination PCR revealed velogenic NDV, which was later confirmed with the presence of the 112-RRQKR*F-117 sequence at the F protein cleavage site. Phylogenetic analysis of full F gene sequences (N=10) confirmed the presence of sub-genotype VII.2 in 9/10 sequences, and genotype II in one sample. These 9 sequences were only 0.7 to 2.6 % divergent with two VII.2 (=VIIi) sequences (HQ697254.1 chicken/Banjarmas/Indonesia and KU862293.1 Parakeet/Karachi/Pakistan) but had 2.2 to 3.6 % diversion from two VII.2 sequences (OR185447 and MZ546197) from India. Then branching was found from sequences of VIIh, VIIk (VII.2), and VIIa (VII.1.2), and then from sub-genotypes VII.1.1 and VII.1.2. Due to less than 5 % diversion, these sequences could not be qualified as new sub-genotype in evolutionary distance analysis. At the amino acid level, our sequences had aa N-T-I-A-L-T at 24-79-125-385-445-482. Whereas at the same positions, in most of the retrieved VII.2 sequences and vaccines, the sequence was S-A-V-T-Q/I- E/A. Two sequences revealed additional six and four amino acid differences,respectively.This indicates rapid continuous genetic evolution of sub-genotype VII.2 and partially explains vaccinal immunity escape.

A time series transcriptome profiling of host cell responses to Newcastle disease virus infection.

Newcastle disease virus (NDV), an avian paramyxovirus, causes major economic losses in the poultry industry worldwide. NDV strains are classified as avirulent, moderately virulent, or virulent according to the severity of the disease they cause. In order to gain a deeper understanding of the molecular mechanisms of virus-host interactions, we conducted Illumina HiSeq-based RNA-Seq analysis on chicken embryo fibroblast (DF1) cells during the first 24 hours of infection with NDV strain Komarov. Comparative analysis of uninfected DF1 cells versus NDV-infected DF1 cells at 6, 12, and 24 h postinfection identified 462, 459, and 410 differentially expressed genes, respectively. The findings revealed an increase in the expression of genes linked to the MAPK signalling pathway in the initial stages of NDV infection. This overexpression potentially aids viral multiplication while hindering pathogen detection and subsequent immune responses from the host. Our findings provide initial insights into the early responses of DF1 cells to NDV infection.

Molecular Cloning, Tissue Distribution and Antiviral Immune Response of Duck Src.

As a founding member of the Src family of kinases, Src has been confirmed to participate in the regulation of immune responses, integrin signaling, and motility. Ducks are usually asymptomatic carriers of RNA viruses such as Newcastle disease virus and avian influenza virus, which can be deadly to chickens. The beneficial role of Src in modulating the immune response remains largely unknown in ducks. Here, we characterized the duck Src and found that it contains a 192-base-pair 5' untranslated region, a 1602-base-pair coding region, and a 2541-base-pair 3' untranslated region, encoding 533 amino acid residues. Additionally, duSrc transcripts were significantly activated in duck tissues infected by Newcastle disease virus compared to controls. The duSrc transcripts were notably widespread in all tissues examined, and the expression level was higher in liver, blood, lung, pancreas, and thymus. Moreover, we found the expression levels of IFN-ß, NF-κB, IRF3, and Src were significantly increased in DEFs after infection with 5'ppp dsRNA, but there was no significant difference before and after treatment in DF1 cells. Furthermore, overexpression of duSrc followed by stimulation with 5'ppp dsRNA led to an elevation of IFN-ß levels. The SH3 and PTKc domains of duSrc contributed to promoting the activity of IFN-ß and NF-κB in DEFs stimulated by 5'ppp dsRNA.

Detection and differentiation of low virulence and virulent Orthoavulavirus javaense using a molecular beacon with RT-LAMP.

Newcastle disease (ND), an economically important disease in poultry, is caused by virulent strains of the genetically diverse Orthoavulavirus javaense (OAVJ). Laboratories rely on quantitative real-time reverse transcription PCR (qRT-PCR) to detect OAVJ and differentiate between OAVJ pathotypes. This study demonstrates that a fusion cleavage site based molecular beacon with reverse transcription loop mediated isothermal amplification (MB-RT-LAMP) assay can detect and differentiate OAVJ pathotypes in a single assay. Data show that the assay can rapidly identify diverse OAVJ genotypes with sensitivity only one log-fold lower than the current fusion qRT-PCR assay (104 copies), exhibits a high degree of specificity for OAVJ, and the molecular beacon can differentiate mesogenic/velogenic sequences from lentogenic sequences. Further, data show that a two-minute rapid lysis protocol preceding MB-RT-LAMP can detect and differentiate OAVJ RNA from both spiked samples and oropharyngeal swabs without the need for RNA isolation. As the MB-RT-LAMP assay can rapidly detect and discriminate between lentogenic and mesogenic/velogenic sequences of OAVJ within one assay, without the need for RNA isolation, and is adaptable to existing veterinary diagnostic laboratory workflow without additional equipment, this assay could be a rapid primary screening tool before qRT-PCR based validation in resource limited settings.

Newcastle viral disease causation web correlations with laying hen productivity.

Environmental conditions profoundly impact the health, welfare, and productivity of laying hens in commercial poultry farming. We investigated the association between microclimate variations, production indices, and histopathological responses to accidental Newcastle disease virus (NDV) infection within a controlled closed-house system. The study was conducted over seven months in a laying hen facility in Cairo, Egypt. Microclimate measurements included temperature, relative humidity (RH%), air velocity (AV), and the temperature humidity index (THI) that were obtained from specific locations on the front and back sides of the facility. Productivity indices, including the egg production percentage (EPP), egg weight (EW), average daily feed intake, and feed conversion ratio, were assessed monthly. During an NDV outbreak, humoral immune responses, gross pathology, and histopathological changes were evaluated. The results demonstrated significant (p < 0.05) variations in EPP and EW between the front and back sides except in April and May. AV had a significant (p = 0.006) positive effect (Beta = 0.346) on EW on the front side. On the back side, AV had a significant (p = 0.001) positive effect (Beta = 0.474) on EW, while it negatively influenced (p = 0.027) EPP (Beta = - 0.281). However, temperature, RH%, and THI had no impact and could not serve as predictors for EPP or EW on either farm side. The humoral immune response to NDV was consistent across microclimates, highlighting the resilience of hens. Histopathological examination revealed characteristic NDV-associated lesions, with no significant differences between the microclimates. This study underscores the significance of optimizing microclimate conditions to enhance laying performance by providing tailored environmental management strategies based on seasonal variations, ensuring consistent airflow, particularly near cooling pads and exhaust fans, and reinforcing the importance of biosecurity measures under field challenges with continuous monitoring and adjustment.

Nucleotide sequence characterization, amino acid variations and 3D structural analysis of HN protein of the NDV VIId genotype.

BACKGROUND: Haemagglutinin-neuraminidase (HN) is one of the membrane proteins of Newcastle disease virus (NDV) that plays a significant role during host viral infection. Therefore, antibodies against HN are vital for the host's ability to protect itself against NDV infection due to their critical functions in viral infection. As a result, HN has been a candidate protein in vaccine development against the Newcastle disease virus. METHODS: This report used the full-length sequence of the HN protein of NDV isolated in Iran (VIId subgenotype). We characterize and identify amino acid substitutions in comparison to other more prevalent NDV genotypes, VII subgenotypes and vaccine strains. Furthermore, bioinformatics tools were applied to determine the three-dimensional structure, molecular dynamics simulation and prediction of B-cell antigenic epitopes. RESULTS: The results showed that the antigenic regions of our isolate are quite comparable to the other VII subgenotypes of NDV isolated from different geographical places. Moreover, by employing the final 3D structure of our HN protein, the amino acid residues are proposed as a B-cell epitope by epitope prediction servers, which leads to the introduction of linear and conformational antigenic sites. CONCLUSIONS: Immunoinformatic vaccine design principles currently exhibit tremendous potential for developing a new generation of candidate vaccines quickly and economically to eradicate infectious viruses, including the NDV. In order to accomplish this, focus is directed on residues that might be considered antigenic.

Thermostable vacuum foam dried Newcastle disease vaccine: Process optimization and pilot-scale study.

Vacuum foam drying (VFD) has been shown to improve the thermostability and long-term shelf life of Newcastle Disease Virus (NDV). This study optimized the VFD process to improve the shelf life of NDV at laboratory-scale and then tested the optimized conditions at pilot-scale. The optimal NDV to T5 formulation ratio was determined to be 1:1 or 3:2. Using the 1:1 virus to formulation ratio, the optimal filling volumes were determined to be 13-17% of the vial capacity. The optimized VFD process conditions were determined to be at a shelf temperature of 25℃ with a minimum overall drying time of 44 h. The vaccine samples prepared using these optimized conditions at laboratory-scale exhibited virus titer losses of ≤ 1.0 log10 with residual moisture content (RMC) below 3%. Furthermore, these samples were transported for 97 days around China at ambient temperature without significant titer loss, thus demonstrating the thermostability of the NDV-VFD vaccine. Pilot-scale testing of the NDV-VFD vaccine at optimized conditions showed promising results for up-scaling the process as the RMC was below 3%. However, the virus titer loss was slightly above 1.0 log10 (approximately 1.1 log10). Therefore, the NDV-VFD process requires further optimization at pilot scale to obtain a titer loss of ≤ 1.0 log10. Results from this study provide important guidance for possible industrialization of NDV-VFD vaccine in the future. KEY POINTS: • The process optimization and scale-up test of thermostable NDV vaccine prepared through VFD is reported for the first time in this study. • The live attenuated NDV-VFD vaccine maintained thermostability for 97 days during long distance transportation in summer without cold chain conditions. • The optimized NDV-VFD vaccine preparations evaluated at pilot-scale maintained acceptable levels of infectivity after preservation at 37℃ for 90 days, which demonstrated the feasibility of the vaccine for industrialization.

The Application of Newcastle Disease Virus (NDV): Vaccine Vectors and Tumor Therapy.

Newcastle disease virus (NDV) is an avian pathogen with an unsegmented negative-strand RNA genome that belongs to the Paramyxoviridae family. While primarily pathogenic in birds, NDV presents no threat to human health, rendering it a safe candidate for various biomedical applications. Extensive research has highlighted the potential of NDV as a vector for vaccine development and gene therapy, owing to its transcriptional modularity, low recombination rate, and lack of a DNA phase during replication. Furthermore, NDV exhibits oncolytic capabilities, efficiently eliciting antitumor immune responses, thereby positioning it as a promising therapeutic agent for cancer treatment. This article comprehensively reviews the biological characteristics of NDV, elucidates the molecular mechanisms underlying its oncolytic properties, and discusses its applications in the fields of vaccine vector development and tumor therapy.

Spray vaccination with a Newcastle disease virus (NDV)-vectored infectious laryngotracheitis (ILT) vaccine protects commercial chickens from ILT in the presence of maternally-derived antibodies.

Infectious laryngotracheitis (ILT) poses a significant threat to the poultry industry, and vaccines play an important role in protection. However, due to the increasing scale of poultry production, there is an urgent need to develop vaccines that are suitable for convenient immunization methods such as spraying. Previous studies have shown that Newcastle disease virus (NDV)-ILT vaccines administered via intranasal and intraocular routes to commercial chickens carrying maternally-derived antibodies (MDAs) are still protective against ILT. In this study, a recombinant NDV (rNDV) was generated to express infectious laryngotracheitis virus (ILTV) glycoprotein B (gB), named rLS-gB, based on a full-length cDNA clone of the LaSota strain. The protective effect of different doses of rLS-gB administered by spray vaccination to commercial chickens at 1 d of age (doa) was evaluated. The chickens were exposed to 160-µm aerosol particles for 10 min for spray vaccination, and no adverse reactions were observed after vaccination. Despite the presence of anti-NDV MDAs and anti-ILTV MDAs in chickens, the ILTV- and NDV-specific antibody titres were significantly greater in the vaccinated groups than in the unvaccinated group. After challenge with a virulent ILTV strain, no clinical signs were observed in the 107 EID50/ml group compared to the other groups. Furthermore, vaccination with 107 EID50/ml rLS-gB significantly reduced the ILTV viral load and ameliorated gross and microscopic lesions in the trachea of chickens. Overall, these results suggested that rLS-gB is a safe and efficient candidate spray vaccine for ILT and is especially suitable for scaled chicken farms.

Effect of co-infection with Newcastle disease virus on Mycoplasma gallisepticum pathogenesis in vivo and in vitro.

The co-infection of Newcastle disease virus (NDV) and Mycoplasma gallisepticum (MG) has a detrimental effect on chicken production performance, exerts a deleterious impact on poultry production performance, resulting in substantial economic losses. However, the exact impact and underlying mechanisms remain ambiguous. In this study, co-infection models were established both in vivo and in vitro. Through these models, it was found that the co-infection facilitated the replication of MG and NDV, as well as MG induced pathogenesis. The administration of lentogenic NDV resulted in the suppression of the innate immune response in vivo. At cellular level, co-infection promoted MG induced apoptosis through caspase-dependent mitochondrial endogenous pathway and suppressed the inflammatory secretion. This research contributes novel insights in co-infection.

Thermostability study of virulent Newcastle disease viruses isolated in Southern Angola.

Newcastle disease (ND) is endemic in Angola. Several outbreaks of ND occurred in small backyard flocks and village chickens with high mortality in the southern provinces of the country, Cunene, Namibe and Huíla, in 2016 and 2018. In those years, 15 virulent ND virus (NDV) strains were isolated and grouped within subgenotype 2 of genotype VII (subgenotype VII.2). We now present a study on the thermostability of the isolates, aiming at the selection of the most thermostable strains that, after being genetically modified to reduce their virulence, can be adapted to the production of vaccines less dependent on cold chain and more adequate to protect native chickens against ND. Heat-inactivation kinetics of haemagglutinin (Ha) activity and infectivity (I) of the isolates were determined by incubating aliquots of virus at 56 °C for different time intervals. The two isolates from Namibe province showed a decrease in infectivity of 2 log10 in ≤ 10 min, therefore belonging to the I-phenotype, but while the NB1 isolate from 2016 maintained the Ha activity up to 30 min and was classified as thermostable virus (I-Ha+), the Ha activity of the 2018 NB2 isolate decreased by 2 log2 in 30 min, being classified as a thermolabile virus (I-Ha-). Of the 13 NDV isolates from Huíla province, 10 isolates were classified as thermostable, eight with phenotype I+Ha+ and 2 with phenotype I-Ha+. The other three isolates from this province were classified as thermolabile viruses (I-Ha-).Contribution: This study will contribute to the control and/or eradication of Newcastle disease virus in Angola. The thermostable viral strains isolated from chickens in the country can be genetically manipulated by reverse genetic technology in order to reduce their virulence and use them as a vaccine in the remote areas of Angola.

Duration of Highly Pathogenic Avian Influenza Virus and Newcastle Disease Virus Infectivity in Dried Ornithologic Study Skins.

Ornithologic study skins are specimens of avian skins that have been preserved by drying after removing the viscera and muscle. Because of the high value of study skins for scientific studies, specimens are shared among researchers. There is concern that study skins might be contaminated with high-consequence diseases such as highly pathogenic avian influenza virus (HPAIV) or Newcastle disease virus (NDV). To mitigate risk, thermal or chemical treatment of study skins may be required before transfer; however, such treatments might damage the specimens. Therefore, a study was conducted to evaluate the duration of infectivity of HPAIV and NDV in study skins prepared from infected chickens (Gallus gallus). Study skins were prepared from 10 chickens infected with each virus. Skin and feather pulp samples were taken at the time of study skin preparation to establish starting titers. Mean starting titers in the skin was 4.2 log10 and 5.1 log10 50% egg infectious doses (EID50) for HPAIV and NDV groups respectively, and were 6.7 log10 EID50 for HPAIV, and 6.4 log10 EID50 for NDV in feather pulp. Samples were collected at 2 and 4 wk of drying to quantify viable virus. At 2 wk, fewer samples had detectable virus and mean titers were 1.8 log10 (skin) and 2.1 log10 (feathers) EID50 for HPAIV, and 1.7 log10 (skin) and 3.5 log10 (feathers) EID50 for NDV. At 4 wk viable virus could not be detected in either tissue type.

Spillover of Newcastle disease virus to Himalayan Griffon vulture: a possible food-based transmission.

The Newcastle disease virus (NDV) affects wild and domesticated bird species, including commercial poultry. Although the diversity of NDV in domestic chickens is well documented, limited information is available about Newcastle disease (ND) outbreaks in other bird species. We report an annotated sequence of NDV/Vulture/Borjuri/01/22, an avirulent strain of NDV reported from Borjuri, Northeast India, in Himalayan Griffon vulture. The complete genome is 15,186 bases long with a fusion protein (F) cleavage site 112GRQGR↓L117. The phylogenetic analysis based on the F protein gene and the whole genome sequence revealed that the isolate from the vulture belongs to genotype II, sharing significant homology with vaccine strain LaSota. The study highlights the possible spillover of the virus from domestic to wild species through the food chain.