Complete Genome Sequence of a Genotype XVII Newcastle Disease Virus, Isolated from an Apparently Healthy Domestic Duck in Nigeria

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.

Effects of dietary supplementation of Vitamins E and C on oxidative stress induced by a Nigerian velogenic strain of the Newcastle disease virus (KUDU 113) in the brain and bursa of Fabricius of broiler chickens

Background and Aim:

Newcastle disease (ND) is widely recognized as an extremely harmful and contagious disease of birds. Therefore, the present study aims to evaluate the effect of oxidative stress induced by the virulent ND virus (NDV) (KUDU 113) on the plasma, brain, bursa of Fabricius, NDV antibody response, and hematology as well as the ameliorative effect of the individual or combined use of Vitamins E and C on the clinical signs of NDV-infected chickens.

Materials and Methods:

In this study, a total of 150 broiler chickens were included and divided into five groups: Group 1, nonsupplemented and unchallenged chickens (UCC); Group 2, nonsupplemented and challenged chickens (ICC); Group 3, Vitamin C-supplemented + challenged chickens; Group 4, Vitamin E-supplemented + challenged chickens; and Group 5, Vitamins E and C-supplemented + challenged chickens. Groups 3, 4, and 5 were supplemented with Vitamins E and C (33 and 400 mg/kg/day, respectively). Virus challenge was done with 0.1 ml of KUDU 113 7 days after the start of vitamin inclusion in their diet. Concentrations of glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), and catalase (CAT) were analyzed in the plasma, brain, and bursa on days 0, 3, and 7 post-infection (pi) using the biochemical method. The blood samples were randomly collected from five chickens in each group for antibody response and hematological analyses on day 0 previtamin treatment and at 0, 3, 7, 10, 14, and 21 days pi (dpi).

Results:

A significant increase in the concentrations of MDA and NO in the NDV-challenged chickens was observed when compared with the UCCs. Moreover, a significant decrease in GSH concentration was observed in the NDV-challenged chickens when compared with the UCCs. The activities of CAT and SOD were reduced markedly in the NDV-challenged chickens. Increases in the mean antibody titers were observed in the NDV-challenged group when compared with the UCCs from days 3 to 21 pi. The mortality rates of groups 1, 2, 3, 4, and 5 were 0%, 30%, 3.3%, 3.3%, and 26.6%, respectively.

Conclusion:

The findings of this study suggest that KUDU 113 causes oxidative stress in the brain and bursa of Fabricius of chickens. Individual supplementation with Vitamin E or C was found to be more effective in ameliorating oxidative stress, improving the immune response, and reducing mortality in KUDU 113 infections than the combined supplementation of Vitamins C and E.

Systematic Review of Important Viral Diseases in Africa in Light of the 'One Health' Concept

Emerging and re-emerging viral diseases are of great public health concern. The recent emergence of Severe Acute Respiratory Syndrome (SARS) related coronavirus (SARS-CoV-2) in December 2019 in China, which causes COVID-19 disease in humans, and its current spread to several countries, leading to the first pandemic in history to be caused by a coronavirus, highlights the significance of zoonotic viral diseases. Rift Valley fever, rabies, West Nile, chikungunya, dengue, yellow fever, Crimean-Congo hemorrhagic fever, Ebola, and influenza viruses among many other viruses have been reported from different African countries. The paucity of information, lack of knowledge, limited resources, and climate change, coupled with cultural traditions make the African continent a hotspot for vector-borne and zoonotic viral diseases, which may spread globally. Currently, there is no information available on the status of virus diseases in Africa. This systematic review highlights the available information about viral diseases, including zoonotic and vector-borne diseases, reported in Africa. The findings will help us understand the trend of emerging and re-emerging virus diseases within the African continent. The findings recommend active surveillance of viral diseases and strict implementation of One Health measures in Africa to improve human public health and reduce the possibility of potential pandemics due to zoonotic viruses.

Triple La Sota re-vaccinations can protect laying chickens for 3 months against drop in egg production caused by velogenic viscerotropic Newcastle disease virus infection

One hundred and ten Isa Brown layers were vaccinated with La Sota, once at point of lay at 18 weeks and three times at peak of lay which occurred at 27–29 weeks of age. Thereafter, they were weekly monitored for haemagglutination inhibition (HI) antibody decline. The first batch A of the layers were challenged with velogenic viscerotropic Newcastle disease (vvND) virus (vvNDV) on day 24 post‐vaccination (PV), when the geometric mean titre (GMT) was 84.4, batch B were challenged on day 48 PV at GMT of 42.2, while batch C were challenged on day 97 PV at GMT of 21.1. The individual chicken HI antibody titres of the 10 layers in batch C at the day of challenge were: 7 layers had HI titres of 16, 2 layers had HI titres of 32 and 1 layer had HI titres of 64. Each challenge in the three batches produced no clinical signs including drop in egg production. But there was initial swelling of the spleen followed by atrophy with high antibody responses. The virus was recovered in all the cloacal swabs on days 3–9 post‐challenge (PC) at low titres. On days 145 PV and 48, post‐Batch C challenge the remaining hyperimmunized unchallenged layers demonstrated a drop in total % egg production (p < .05) and changes in egg quality. The HI GMT was 256. The virus was recovered in all the cloacal swabs on days 3–9 following appearance of clinical signs. There was no mortality in the experiment. Based on the above observations, it is concluded that triple La Sota re‐vaccination can protect layers against a drop in egg production in areas where vvNDV infection is enzootic.

Pullets had higher bursal and thymic weight indices and more antibody response to La Sota vaccination than broiler chickens (Gallus gallus domesticus)

This study investigated the immune responses to La Sota vaccination, used in protection of chickens against Newcastle disease, in light weight type breeds of chickens (pullets) and heavy weight type breeds of chickens (broilers) used in commercial poultry production. Seven-week-old 50 White Marshall broilers (Br) and 50 Isa Brown pullets (Pu) were randomly divided into four groups: vaccinated broilers chickens; (VBr), unvaccinated broiler chickens (UBr), and vaccinated pullet chickens (VPu) and unvaccinated pullet chickens (UPu). Chickens in groups VBr and VPu were vaccinated with La Sota vaccine, whereas groups UBr and UPu were not vaccinated. On day 0 post vaccination (PV), six chickens from group Br and Pu, and on day 4 PV, three chickens from each four groups were sacrificed and the bursa weight index (BWI), thymus weight index (TWI) and the splenic weight index (SWI) were obtained. The chickens were observed for clinical signs and lesions. Serum samples were collected from the chickens in all the groups on days 0, 7, 14, 21, 28 PV and assayed for haemagglutination inhibition (HI) antibodies. The BWI, TWI and SWI were 0.37 ± 0.05, 0.35 ± 0.17, 0.65 ± 0.26 for pullets and 0.11 ± 0.04, 0.13 ± 0.02, 0.36 ± 0.17 for broilers on day 0 PV. On day 4 PV there was no significant difference (p < .05) between the indices of the vaccinated and unvaccinated chickens. The geometrical mean antibody titres (GMT) of the pullets were 2 to 3 times higher than those of the broilers on days 7 to 28 PV. Vaccination did not produce clinical signs or lesions. The above observations show that naturally pullets produce higher antibodies than broilers because of their higher BWI.

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

Newcastle disease (ND) is one of the most important avian diseases with considerable threat to the productivity of poultry all over the world. The disease is associated with severe respiratory, gastrointestinal, and neurological lesions in chicken leading to high mortality and several other production related losses. The aetiology of the disease is an avian paramyxovirus type-1 or Newcastle disease virus (NDV), whose isolates are serologically grouped into a single serotype but genetically classified into a total of 19 genotypes, owing to the continuous emergence and evolution of the virus. In Nigeria, molecular characterization of NDV is generally very scanty and majorly focuses on the amplification of the partial F gene for genotype assignment. However, with the introduction of the most objective NDV genotyping criteria which utilize complete fusion protein coding sequences in phylogenetic taxonomy, the enormous genetic diversity of the virus in Nigeria became very conspicuous. In this review, we examine the current ecological distribution of various NDV genotypes in Nigeria based on the available complete fusion protein nucleotide sequences (1662 bp) in the NCBI database. We then discuss the challenges of ND control as a result of the wide genetic distance between the currently circulating NDV isolates and the commonest vaccines used to combat the disease in the country. Finally, we suggest future directions in the war against the economically devastating ND in Nigeria.

Immunity Elicited by a Turkey Herpesvirus-Vectored Newcastle Disease Vaccine in Turkey Against Challenge With a Recent Genotype IV Newcastle Disease Virus Field Strain

Newcastle disease (ND) is still a major poultry disease worldwide. Vaccination remains the principal method of controlling ND in endemic countries. Various vaccination strategies, including the use of recently developed recombinant vaccines, have been used to control it. Recombinant vaccines that use the herpesvirus of turkey (HVT) as a vector to express one of the key antigens of Newcastle disease virus (NDV) have been developed to overcome some of the drawbacks related to the use of conventional vaccines. HVT as a vector appears to have unique beneficial characteristics: it is extremely safe, it is not affected by the presence of maternally derived antibodies, and therefore can be applied in the hatchery either in ovo or to day-old chicks. Due to its persistence in the bird, the HVT vector can be expected to induce life-long immune stimulation. In the present study, the efficacy of an HVT-based vector vaccine expressing the F gene of NDV (rHVT-F) was tested against a velogenic genotype IV NDV challenge in commercial turkeys with high levels of maternal antibodies (8.7 ± 0.8 log₂ hemagglutination inhibition titer). The birds were vaccinated on the day of hatch by the subcutaneous route. Development of a humoral immune response to vaccination was detectable from 4 weeks of age by ELISA. The challenge strain used represents recent NDV genotype IV field strains from Morocco. Challenge with this strain induced ND-specific clinical signs and stunting without subsequent mortality in the non-vaccinated birds, whereas the vaccinated turkey poults showed protection as early as 3 weeks of age based on lack of clinical signs, better body weight gain, and reduction of challenge virus shedding. This is the first reported efficacy study of an HVT-vectored ND vaccine against a velogenic NDV challenge in commercial turkeys.

La Sota vaccination may not protect against virus shedding and the lesions of velogenic Newcastle disease in commercial turkeys

The aim of this project is to study the clinical signs and lesion of velogenic Newcastle disease (vND) in commercial turkeys, and also to find out if La Sota vaccination offered protection against these signs and lesions. The cockerels were included as positive controls. One hundred and twenty turkey poults and cockerels were divided into eight groups as follows: unvaccinated unchallenged turkeys (UUT), unvaccinated challenged turkeys (UCT), vaccinated unchallenged turkeys (VUT), vaccinated challenged turkeys (VCT), and along the same lines, the cockerel groups were UUC, UCC, VUC and vaccinated challenged cockerels (VCC). Vaccination was at 3 weeks of age while challenge was at 6 weeks of age. The unvaccinated turkeys and cockerels (UCT and UCC) showed different degrees of depression, diarrhoea and later paralysis at challenge. Total mortality was 100% in cockerels within 6 days, but 60% in turkeys. Similar but milder clinical signs were found in the VCC with a total mortality of 13.3%. The VCT showed mild drop in feed and water consumption, and no mortality. All the challenged groups had significant (p < 0.05) loss of weight when compared with their controls. Necropsy showed that while the UCC had severe proventricular haemorrhages, intestinal and caecal tonsil ulcers, the UCT had no digestive tract lesion. There was severe atrophy of the lymphoid organs in all the challenged groups. Histopathological sections of the bursa, spleen and thymus in all the challenged groups with special emphasis on the vaccinated and unvaccinated turkeys with mortalities of 0 and 60%, respectively, had very severe necrosis and depletion of the lymphoid tissue. Virus was isolated from the cloacal swabs. The haemagglutination inhibition antibodies were significantly higher (p < 0.05) in the challenged groups than the unchallenged. The above observations in the intestinal tracts of UCT are of diagnostic significance while the gross and microscopic lesions in the UCT and VCT show that La Sota vaccination may not protect turkeys against the destruction of the lymphoid organs by vND as earlier reported in chickens. This may lead to immunosuppression and production problems in areas where vND is enzootic.

A robust and cost-effective approach to sequence and analyze complete genomes of small RNA viruses

Background

Next-generation sequencing (NGS) allows ultra-deep sequencing of nucleic acids. The use of sequence-independent amplification of viral nucleic acids without utilization of target-specific primers provides advantages over traditional sequencing methods and allows detection of unsuspected variants and co-infecting agents. However, NGS is not widely used for small RNA viruses because of incorrectly perceived cost estimates and inefficient utilization of freely available bioinformatics tools.

Methods

In this study, we have utilized NGS-based random sequencing of total RNA combined with barcode multiplexing of libraries to quickly, effectively and simultaneously characterize the genomic sequences of multiple avian paramyxoviruses. Thirty libraries were prepared from diagnostic samples amplified in allantoic fluids and their total RNAs were sequenced in a single flow cell on an Illumina MiSeq instrument. After digital normalization, data were assembled using the MIRA assembler within a customized workflow on the Galaxy platform.

Results

Twenty-eight avian paramyxovirus 1 (APMV-1), one APMV-13, four avian influenza and two infectious bronchitis virus complete or nearly complete genome sequences were obtained from the single run. The 29 avian paramyxovirus genomes displayed 99.6% mean coverage based on bases with Phred quality scores of 30 or more. The lower and upper quartiles of sample median depth per position for those 29 samples were 2984 and 6894, respectively, indicating coverage across samples sufficient for deep variant analysis. Sample processing and library preparation took approximately 25–30 h, the sequencing run took 39 h, and processing through the Galaxy workflow took approximately 2–3 h. The cost of all steps, excluding labor, was estimated to be 106 USD per sample.

Conclusions

This work describes an efficient multiplexing NGS approach, a detailed analysis workflow, and customized tools for the characterization of the genomes of RNA viruses. The combination of multiplexing NGS technology with the Galaxy workflow platform resulted in a fast, user-friendly, and cost-efficient protocol for the simultaneous characterization of multiple full-length viral genomes. Twenty-nine full-length or near-full-length APMV genomes with a high median depth were successfully sequenced out of 30 samples. The applied de novo assembly approach also allowed identification of mixed viral populations in some of the samples.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0741-5) contains supplementary material, which is available to authorized users.

Newcastle disease in Nigeria: epizootiology and current knowledge of circulating genotypes

Over the years, Newcastle disease (ND) has defied all available control measures. The disease has remained at the forefront of infectious diseases afflicting poultry production after avian influenza. Despite the continuous global use of million doses of ND vaccine annually, the causative pathogen, avian paramyxovirus type 1 also known as Newcastle disease virus (NDV) has continued to evolve causing, even more, a threat not only to the unvaccinated but the vaccinated flocks inclusive. The disease has been well studied in the developed countries where the virus is found in circulation. However, limited information exists on the epizootiology and circulating genotypes of the virus in developing countries where the majority of the flocks are raised on the extensive management system. Identification of virulent NDV in apparently healthy free-range ducks in this system calls for concern and pragmatic approach to investigate factor(s) that favour the virus inhabiting the ducks without clinical manifestation of the disease. Recently, novel genotypes (XIV, XVII, and XVIII) with peculiarity to West and Central African countries have been discovered and due to lack or poor surveillance system possibility of hitherto unreported genotypes are likely. This review elucidates and discusses available literature on the diversity of the circulating NDV genotypes across the West Africa countries and the epizootiology (molecular) of the disease in Nigeria with the view of identifying gaps in knowledge that can assist in the development of effective vaccines and control strategies to combat the peril of the disease.