Complete genome sequences of newcastle disease virus strains isolated from three different poultry species in china

Molecular and virological characterization of the first poultry outbreaks of Genotype VII.2 velogenic avian orthoavulavirus type 1 (NDV) in North-West Europe, BeNeLux, 2018

After two decades free of Newcastle disease, Belgium encountered a velogenic avian orthoavulavirus type 1 epizootic in 2018. In Belgium, 20 cases were diagnosed, of which 15 occurred in hobby flocks, 2 in professional poultry flocks and 3 in poultry retailers. The disease also disseminated from Belgium towards the Grand Duchy of Luxembourg by trade. Independently, the virus was detected once in the Netherlands, almost simultaneously to the first Belgian detection. As such Newcastle disease emerged in the entire BeNeLux region. Both the polybasic sequence of the fusion gene cleavage site and the intracerebral pathotyping assay demonstrated the high pathogenicity of the strain. This paper represents the first notification of this specific VII.2 subgenotype in the North-West of Europe. Time-calibrated full genome phylogenetic analysis indicated the silent or unreported circulation of the virus prior to the emergence of three genetic clusters in the BeNeLux region without clear geographical or other epidemiological correlation. The Dutch strain appeared as an outgroup to the Belgian and Luxembourgian strains in the time-correlated genetic analysis and no epidemiological link could be identified between the Belgian and Dutch outbreaks. In contrast, both genetic and epidemiological outbreak investigation data linked the G.D. Luxembourg case to the Belgian outbreak. The genetic links between Belgian viruses from retailers and hobby flocks only partially correlated with epidemiological data. Two independent introductions into the professional poultry sector were identified, although their origin could not be determined. Animal experiments using 6-week- old specific pathogen-free chickens indicated a systemic infection and efficient transmission of the virus. The implementation of re-vaccination in the professional sector, affected hobby and retailers, as well as the restriction on assembly and increased biosecurity measures, possibly limited the epizootic and resulted in the disappearance of the virus. These findings emphasize the constant need for awareness and monitoring of notifiable viruses in the field.

Pathobiology of Avian avulavirus 1: special focus on waterfowl

Avian avulaviruses serotype 1 (abbreviated as APMV-1 for the historical name avian paramyxovirus 1) are capable of infecting a wide spectrum of avian species with variable clinical symptoms and outcomes. Ease of transmission has allowed the virus to spread worldwide with varying degrees of virulence depending upon the virus strain and host species. The emergence of new virulent genotypes from global epizootics, and the year-to-year genomic changes in low and high virulence APMV-1 imply that distinct genotypes of APMV-1 are simultaneously evolving at different geographic locations across the globe. This vast genomic diversity may be favoured by large variety of avian species susceptibility to APMV-1 infection, and by the availability of highly mobile wild birds. It has long been considered that waterfowls are not sensitive to APMV-1 and are unable to show any clinical signs, however, outbreaks from the 90's contradict these concepts. The APMV-1 isolates are increasingly reported from the waterfowl. Waterfowl have strong innate immune responses, which minimize the impact of virus infection, however, are unable to prevent the viral shedding. Numerous APMV-1 are carried by domestic waterfowl intermingling with terrestrial poultry. Therefore, commercial ducks and geese should be vaccinated against APMV-1 to minimize the virus shedding and for the prevention the transmission. Genetic diversity within APMV-1 demonstrates the need for continual monitoring of viral evolution and periodic updates of vaccine seed-strains to achieve efficient control and eradication of APMV-1 in waterfowls.

Effects of dietary Lactobacillus acidophilus and Bacillus subtilis on laying performance, egg quality, blood biochemistry and immune response of organic laying hens

The objective of this study was to evaluate the effects of two different probiotic micro-organisms on the performance, egg quality and blood parameters of organically reared hens. A total of 900 16-week-old Hy-Line layer hybrids were randomly assigned to three groups of 300 birds each. The control (CTR) group was fed a corn-soya bean cake-based diet; the L group was fed the same diet supplemented with 0.1% Lactobacillus acidophilus, while the B group was fed the same diet supplemented with 0.05% Bacillus subtilis. Data were recorded at the beginning (weeks 5 and 6: T1) and at the end (weeks 19 and 20: T2) of the experiment, and no differences in hen performance were recorded between dietary groups or sampling times. All of the investigated clinical chemistry parameters, except GGT, were affected by diet (p < 0.05), with the best results recorded for the probiotic-treated groups. The immune-response values showed higher blood bactericidal activity in the B and L groups at T2 (p < 0.05) and a lower lysozime concentration in the B group at T1. Higher antibody production against Newcastle disease virus was observed in the L group compared to the CTR (p = 0.013). No differences in oxidative status were recorded, and no effects of diet on egg quality were observed. Among the physical egg characteristics, only the Roche scale colour was affected by diet (p < 0.05): the egg yolk was paler in the L group. The age of the hen was the most relevant factor affecting physical egg characteristics. The chemical parameters of the egg were almost unaffected by supplementation with probiotics except for the lipid content, which decreased with the L diet (p < 0.05). Both probiotic inclusions had beneficial effects on hen metabolism and welfare, and L. acidophilus induced the best immune response.

Genomic Characterizations of Six Pigeon Paramyxovirus Type 1 Viruses Isolated from Live Bird Markets in China during 2011 to 2013

The genomes of six pigeon paramyxovirus type 1 (PPMV-1) isolated from symptomless pigeons in live poultry markets during the national active surveillance from 2011 to 2013 were sequenced and analyzed in this study. The complete genome lengths of all isolates were 15,192 nucleotides with the gene order of 3’-NP-P-M-F-HN-L-5’. All isolates had the same motif of ¹¹²RRQKRF¹¹⁷ at the cleavage site of the fusion protein, which was typical of velogenic Newcastle disease virus (NDV). Several mutations were identified in the functional domains of F and HN proteins, including fusion peptide, heptad repeat region, transmembrane domains and neutralizing epitopes. Phylogenetic analysis based on sequences of complete genomes and six genes revealed that all isolates belonged to genotype VI in class II, but at least 2 sub-genotypes were identified. Most isolates were placed into sub-genotype VIb with the exception of pi/GX/1015/13, which was classified in sub-genotype VIa. The obvious antigenic difference between PPMV-1 isolates and La Sota strain was found based on the R-value calculated by cross hemagglutination inhibition (HI) assay. These results provided the evidence that PPMV-1 could be detected from healthy pigeons, and our study may be useful in designing vaccines used in pigeon, and developing molecular diagnostic tools to monitor and prevent future PPMV-1 outbreaks.

Identification of a Genotype VIId Newcastle Disease Virus Isolated from Sansui Sheldrake Ducks in Guizhou Province, China

In this study, we report the complete genome sequence of a novel Newcastle disease virus (NDV) strain, Sheldrake duck/China/Guizhou/SS1/2014, isolated from Sansui Sheldrake duck flocks in Guizhou Province, southwestern China. The genome of this isolate is 15,192 nucleotides in length, which belongs to NDV genotype VIId in class II. This discovery will help us further study the epidemiology characteristics and molecular pathogenesis of genotype VIId NDV in Sansui Sheldrake ducks.

The deletion of an extra six nucleotides in the 5' -untranslated region of the nucleoprotein gene of Newcastle disease virus NA-1 decreases virulence

Background

The virulent Newcastle disease virus (NDV) strain NA-1 (genotype VII) was isolated from an epizootic involving a flock of geese in Jilin Province, Northeast China, in 1999. Compared with the classical NDV strains, which have a genome size of 15,186 bp, the more recently isolated NDV strains, including that involved in the goose outbreak, have an extra six nucleotides in the 5′-untranslated region (UTR) of the nucleoprotein (NP) gene. This extra sequence, TCCCAC, is highly conserved and has been found in multiple NDV strains, including ZJ-1, WF00G, JSG0210, and NA-1. In the current study, an infectious clone from strain NA-1 was isolated and designated rNA-1. Subsequently, strain rNA-1 was mutated to delete the six-nucleotide insertion, producing strain rNA-1(−). Virulence of the recombinant virus was then assayed in chickens and geese.

Results

The recombinant virus rNA-1(−) showed similar biological characteristics to the parental NA-1 strain in DF-1 chicken fibroblast cells. However, the virulence of rNA-1(−) in 9-day-old embryonated chicken eggs and 1-day-old specific pathogen-free (SPF) chickens was decreased compared with the rNA-1 control. Furthermore, the virulence of the recombinant strain was slightly decreased in 1-day-old SPF chickens when compared with that in 1-day-old geese.

Conclusion

Following deletion of six nucleotides in the 5′-UTR of the NP gene of NDV strain NA-1, the virulence of the rNA-1(−) recombinant strain was decreased in both chickens and geese. However, rNA-1(−) was more virulent in chickens than geese, as seen by the higher intracerebral pathogenicity index value.

Development of strand-specific real-time RT-PCR to distinguish viral RNAs during Newcastle disease virus infection

Newcastle disease virus (NDV) causes large losses in the global fowl industry. To better understand NDV replication and transcription cycle, quantitative detection methods for distinguishing NDV genomic RNA (gRNA), antigenomic RNA (cRNA), and messenger RNA (mRNA) in NDV-infected cells are indispensible. Three reverse transcription primers were designed to specifically target the nucleoprotein (NP) region of gRNA, cRNA, and NP mRNA, and a corresponding real-time RT-PCR assay was developed to simultaneously quantify the three types of RNAs in NDV-infected cells. This method showed very good specificity, sensitivity, and reproducibility. The detection range of the assay was between 5.5 × 10² and 1.1 × 10⁹ copies/μL of the target gene. These methods were applied to investigate the dynamics of the gRNA, cRNA, and mRNA synthesis in NDV La Sota infected DF-1 cells. The results showed that the copy numbers of viral gRNA, cRNA, and NP mRNA all exponentially increased in the beginning. The viral RNA copy number then plateaued at 10'h postinfection and gradually decreased from 16 h postinfection. No synthesis priority was observed between replication (gRNA and cRNA amounts) and transcription (mRNA amounts) during NDV infection. However, the cRNA accumulated more rapidly than gRNA, as the cRNA copy number was three- to tenfold higher than gRNA starting from 2 h postinfection. Conclusion. A real-time RT-PCR for absolute quantitation of specific viral RNA fragments in NDV-infected cells was developed for the first time. The development of this assay will be helpful for further studies on the pathogenesis and control strategies of NDV.