Development of a real-time reverse-transcription PCR for detection of newcastle disease virus RNA in clinical samples

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.

Isolation and whole genome sequencing of North American lineage class I avian orthoavulavirus 1 isolated from wild Eurasian teal in South Korea

We report the first North American origin class I avian orthoavulavirus 1 (AOAV-1) isolated from a faecal dropping of wild Eurasian teal (Anas crecca) in South Korea. Whole genome sequencing and comparative phylogenetic analysis revealed that the AOAV-1/Eurasian teal/South Korea/KU1405-3/2017 virus belongs to the sub-genotype 1.2 of class I AOAV-1. Phylogenetic analysis suggested multiple introductions of the North American sub-genotype 1.2 viruses into Asia and its establishment in the wild bird population in East Asia since May 2011. These results provide information on the epidemiology of AOAV-1, particularly the role of migratory wild birds in exchanging viruses between the Eurasian and North American continents. Enhanced genomic surveillance is required to improve our understanding on the evolution and transmission dynamics of AOAV-1 in wild birds.

Genetic Sequence and Pathogenicity of Infectious Bursal Disease Virus in Chickens in Egypt During 2017-2021

The continued circulation of infectious bursal disease virus (IBDV) in Egypt, despite the use of various vaccines, is a serious problem that requires continuous detection of IBDV. In the current study, real-time reverse transcriptase polymerase chain reaction testing of 100 diseased chicken flocks during 2017-2021 revealed the presence of very virulent IBDV (vvIBDV) in 67% of the flocks, non-vvIBDV in 11%, and a mixture of both vvIBDV and non-vvIBDV in 4%. Twenty-nine IBDV isolates were submitted for partial sequencing of the viral protein 2 hypervariable region (VP2-HVR), and 27 isolates were confirmed to be genogroup A3 (vvIBDV) with 96.3%-98.5% similarity to the global A3 (vvIBDV) and 88.9%-97% similarity to genogroup A1 vaccine strains. The remaining two isolates were non-vvIBDV and showed 91.1% and 100% identity with classical genogroup A1 strains, respectively. Furthermore, the sequence and phylogenetic analysis of VP1 (amino acids 33-254) of two selected isolates of A3, 5/2017 and 98/2021, clustered them as B2, vvIBDV-like, strains with high similarity (99.5%) to four Egyptian, 99% to Chinese and European, and 97.7% to Chinese and Polish vvIBDV isolates. Experimental infection of commercial broiler chickens with two vvIBDV-A3B2 isolates (5/2017 and 98/2021) showed no mortality despite typical tissue lesions, clear histopathological changes, and strong ELISA antibody response. Isolate 98/2021 was more pathogenic, as confirmed by histopathology, whereas isolate 5/2017 induced a stronger serological response. In conclusion, vvIBDV (A3B2) strains with two amino acid (aa) substitutions in VP1 as V141I and V234I as well as VP2 as Y220F and G254S are still circulating in Egypt.

Molecular Detection and Characterization of Newcastle Disease Virus from Chickens in Mid-Rift Valley and Central Part of Ethiopia

Background

Newcastle disease (ND) is a highly infectious poultry disease that causes major economic losses worldwide. The disease is caused by Newcastle Disease Virus (NDV) and early detection and identification of the viral strain is essential. Having knowledge of the NDV strain genotype that circulates in some regions would help in designing an effective vaccine to control the disease. In this regard, there is little information on NDV strain in chickens in mid Rift Valley and the central part of Ethiopia. Therefore, the purpose of this study was to detect and characterize NDV strain genotype from chickens in mid-Rift Valley and the central part of Ethiopia and test whether this NDV strain genotype matches the vaccine strain currently used in the study area.

Methods

A total of 98 samples: 78 (tracheal and cloacal) swabs from chicken pools of five and 20 tissue samples were collected. To detect NDV strain, conserved region of the virus Matrix (M) gene was amplified by qRT-PCR. To characterize NDV strain genotypes, M-gene positive samples were specifically re-amplified by conventional PCR targeting the Fusion (F) gene region and sequenced by Sanger method.

Results

13.26% of tested samples were positive for NDV strain in the study area with statistically significant difference (P<0.05) among the study sites. Further characterization of the F genes from NDV strain isolates by phylogenetic analysis indicated that one field isolate clustered with genotype VII whereas three of the isolates clustered to genotype I, II, and III. The isolate of the current NDV strain vaccine in use in the study area clustered with genotype II.

Conclusion

The current study indicates the existence of different NDV strain genotype from that of the vaccine strain currently used. Even though large-scale characterization of several isolates is required at national level, the current study laid baseline information for the existence of variations between field NDV strain genotype and vaccine strain currently used against ND in the country.

Herpesvirus and Subsequent Usutu Virus Infection in a Great Grey Owl (Strix nebulosa) at the Ljubljana Zoo, Slovenia

Herpesvirus (HV) has been known to cause disease in owls, with various clinical signs and outcomes for the last several decades. The HV DNA polymerase gene was detected in oropharyngeal and cloacal swabs of a male great grey owl (Strix nebulosa) in a zoological collection in Ljubljana, Slovenia. In the following 4 months, despite continuous HV detection in swabs, no clinical signs with a clear link to HV disease were observed. Hepatoprotective and immunostimulant therapies applied during this period did not prevent HV shedding. Therefore, peroral antiviral therapy with acyclovir (150 mg/kg q24 h for seven days) was performed, and the owl tested negative at the next sampling and remained negative for the next 8 months. After that, the owl again tested positive for HV presence, and the same protocol with antiviral therapy was performed. After 3 weeks with a negative test for HV presence, without any clinical signs of illness, the owl suddenly died because of Usutu virus (USUV) infection. Among all the owls at the zoo, interestingly, only the HV-positive great grey owl died because of USUV infection. The USUV sequence detected and obtained in this study clusters together with other Europe 2 sequences detected in neighboring countries. Our study shows the potential of acyclovir therapy in the prevention of herpesvirus shedding and, moreover, lowering the possibility for spreading HV to other owls and birds. To the best of our knowledge, this is the first report of HV presence and USUV infection in a great grey owl in Slovenia.

Respiratory disease complex due to mixed viral infections in chicken in Jordan

The global distribution of avian respiratory viruses highlights the need for effective surveillance programs and international collaboration to monitor viral circulation and implement timely control measures. In the current study, we aim to provide a comprehensive overview of avian respiratory viral infections in the poultry flocks in Jordan, focusing on the major viruses involved, their epidemiology, clinical manifestations, and evolution based on viroinformatics that will be helpful to improve the diagnostic methods, and control strategies including vaccines in the region. In this research, various poultry broiler groups in Jordan experiencing respiratory symptoms were tested for respiratory viral pathogens from January 2021 to February 2022. The mortality rates observed in the examined groups varied between 6% and 40%. The identified strains were authenticated using the RT-qPCR assay. Furthermore, they underwent in-depth characterisation through the sequencing of the complete spike (S1) gene for infectious bronchitis virus (IBV) and the haemagglutinin (HA) gene for avian influenza virus (AIV) subtype H9N2. Co-infection of IBV and AIV H9N2 viruses was detected through molecular analysis. The IBV strains showed affiliation with the variant groups GI-16 (3 strains) and GI-23 (9 strains) and exhibited numerous mutations. Meanwhile, H9N2 avian influenza viruses displayed various changes in amino acids within the HA gene, suggesting the influence of antibody-driven selection pressure. The phylogenetic analysis revealed that the H9N2 viruses identified in this investigation shared close genetic ties with EG3 (3 strains) and the Middle East group (ME1; 8 strains). These strains have been recently found in Jordan and nearby countries in the Middle East. Moreover, their HA genes exhibited similarities to viruses belonging to the G1-like lineage. In conclusion, avian respiratory viral infections remain a significant concern for the poultry industry, requiring constant vigilance and proactive measures to minimise their impact. Continued surveillance, robust diagnostic methods, effective vaccines, and international cooperation are essential components of a comprehensive approach to combat avian respiratory viral infections (AI, IBV, ND and ILT 'viruses) and safeguard avian health and global poultry production.

Cytokine expression, protection and shedding reduction induced by the combination of lipopolysaccharide with Montanoid ISA71 in oil-based Newcastle disease vaccine

Oil-based inactivated ND vaccines are a commonly used control strategy for this endemic disease in Egypt. One of the major limitations of these inactivated vaccines is the time taken to develop a protective response in vaccinated birds. In the present study, we aimed to formulate an inactivated oil-based ND vaccine incorporated with lipopolysaccharide (LPS) that stimulates the early onset innate response to inactivated vaccines via proinflammatory cytokine production. Five groups of 21-day old SPF chicks were reared in isolators and were treated as follows: G1: Montanoid ISA71 adjuvanted NDV vaccinated group, G2: LPS and Montanoid ISA71 adjuvanted NDV vaccinated group, G3: LPS and Montanoid ISA71 with phosphate buffer saline received group and two non-vaccinated control groups. NDV specific antibodies and cell mediated immune responses were evaluated by hemagglutination inhibition and lymphocyte proliferation tests, respectively. Transcriptional responses of the TLR4, IFN-γ and IL-2 genes were analyzed in peripheral blood mononuclear cells (PBMCs) following vaccination by qRT-PCR. Protection % was determined after challenge with a lethal strain of NDV 106 EID50/0.5 ml. Viral shedding was assessed on oropharyngeal swabs by qRT-PCR and infectivity titration on SPF-ECE. The results revealed that the incorporation of LPS with ISA71 in the oil-based ND vaccine induced a synergistic response confirmed by significant humoral and lymphoproliferative responses with a significant increase in Th1 cytokine transcripts. The simultaneous use of both adjuvants in G2 demonstrated complete protection and a significant reduction in viral shedding compared to the ISA71-adjuvated ND vaccine in G1, which conferred 90 % protection.

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.

Isolation, Molecular, and Histopathological Patterns of a Novel Variant of Infectious Bursal Disease Virus in Chicken Flocks in Egypt

After an extended period of detecting classical virulent, attenuated, and very virulent IBDV, a novel variant (nVarIBDV) was confirmed in Egypt in this study in 18, IBD vaccinated, chicken flocks aged 19-49 days. Partial sequence of viral protein 2 (VP2) [219 aa, 147-366, resembling 657 bp] of two obtained isolates (nos. 3 and 4) revealed nVarIBDV (genotype A2d) and OR682618 and OR682619 GenBank accession numbers were obtained. Phylogenetic analysis revealed that both nVarIBDV isolates were closely related to nVarIBDV strains (A2d) circulating in China, exhibiting 100% identity to SD-2020 and 99.5-98.1% similarity to ZD-2018-1, QZ, GX and SG19 strains, respectively. Similarity to USA variant strains, belonging to genotypes A2b (9109), A2c (GLS) and A2a (variant E), respectively, was 95.5-92.6%. Also, the VP2 hypervariable region in those two, A2d, isolates revealed greater similarities to Faragher 52/70 (Vaxxitek®) at 90.4% and to an Indian strain (Ventri-Plus®) and V217 (Xtreme®) at 89.7% and 86-88.9% in other vaccines. Histopathological examination of both the bursa of Fabricius and spleen collected from diseased chickens in flock no. 18 revealed severe atrophy. In conclusion, further studies are required to investigate the epidemiological situation of this novel genotype across the country, and to assess various vaccine protections against nVarIBDV. Additionally, vaccination of breeders with inactivated IBD vaccines including this nVarIBDV is essential to obtain specific maternal antibodies in their broilers.

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.

The 28S rRNA RT-qPCR assay for host depletion evaluation to enhance avian virus detection in Illumina and Nanopore sequencing

Abundant host and bacterial sequences can obscure the detection of less prevalent viruses in untargeted next-generation sequencing (NGS). Efficient removal of these non-targeted sequences is vital for accurate viral detection. This study presents a novel 28S ribosomal RNA (rRNA) RT-qPCR assay designed to assess the efficiency of avian rRNA depletion before conducting costly NGS for the detection of avian RNA viruses. The comprehensive evaluation of this 28S-test focuses on substituting DNase I with alternative DNases in our established depletion protocols and finetuning essential parameters for reliable host rRNA depletion. To validate the effectiveness of the 28S-test, we compared its performance with NGS results obtained from both Illumina and Nanopore sequencing platforms. This evaluation utilized swab samples from chickens infected with highly pathogenic avian influenza virus, subjected to established and modified depletion protocols. Both methods significantly reduced host rRNA levels, but using the alternative DNase had superior performance. Additionally, utilizing the 28S-test, we explored cost- and time-effective strategies, such as reduced probe concentrations and other alternative DNase usage, assessed the impact of filtration pre-treatment, and evaluated various experimental parameters to further optimize the depletion protocol. Our findings underscore the value of the 28S-test in optimizing depletion methods for advancing improvements in avian disease research through NGS.

First detection of herpesvirus and hemosporidians in the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus)

Pathogens affect wild bird populations worldwide, contributing to their decline. Considering the scarce health data regarding the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus), we molecularly surveyed selected pathogens (Newcastle disease virus, Avian influenza virus, Chlamydia psittaci, avian pathogenic Escherichia coli, Campylobacter jejuni, and Salmonella spp.) in 30 Pyrenean Capercaillie feces collected in the field (Catalonia, northeastern Spain). Additionally, swab and tissue samples from eight wild Pyrenean Capercaillies of Catalonia and Andorra were molecularly tested for herpesvirus and hemosporidians (Plasmodium spp., Haemoproteus spp., and Leucocytozoon spp.). All fecal samples were negative for the pathogens tested. Nevertheless, we detected a novel herpesvirus in 50% (4/8) of the Pyrenean Capercaillies, and hemosporidian DNA in 62.5% (5/8) of the tissue samples (i.e., Haemoproteus sp. [4 of 8] and/or Leucocytozoon sp. [3 of 8]). To our knowledge, this is the first detection of herpesvirus and hemosporidians infections in Pyrenean Capercaillies. The putative novel herpesvirus belongs to the genus Iltovirus. The presence of hemosporidian parasites in this mountain bird species is of concern, and could be related to the marked increase in the average temperature in the Pyrenees as a consequence of climate change. Our findings are fundamental to improve the conservation plans for the endangered Pyrenean Capercaillie population.

Molecular characterization of chicken astrovirus and pathogenicity of a novel isolate in China

As an enteric virus, chicken astrovirus has been related to various kinds of diseases in chickens, including white chick syndrome, runting-stunting syndrome, severe kidney disease, urate deposits and visceral gout, generating economic losses in the poultry industry globally. The complete ORF2 gene of 31 CAstV isolates in six provinces of China during 2020-2022 was characterized and analyzed with the purpose of better understanding the molecular epidemiology and genetic diversity of CAstV field isolates. Phylogenetic analysis which was based on the complete ORF2 (capsid) amino acid sequence of 31 CAstV isolates and 57 reference strains indicated that 2 isolates belonged to subgroup Ai, 10 isolates belonged to subgroup Bi, 3 isolates belonged to subgroup Bii, 5 isolates belonged to subgroup Biii, 7 isolates belonged to subgroup Biv, 3 isolates belonged to subgroup Bv, and one isolate (JS202103) belonged to a new B subgroup. In addition, the novel CAstV strain JS202103 was successfully isolated in vitro, and its whole genome shared 76.9-94.3% identity with the 29 CAstV reference strains. JS202103 caused hatchability reduction, dead embryos, kidney disease and visceral gout in chicken embryos. Moreover, this is the also the initial study focusing on diverse CAstV strains including subgroups Biii, Biv, and Bv circulate in China. The current work contributes to improving our understanding of CAstV isolates in China, and it will also provide references for developing efficient measures to control this virus.

A novel array of real-time RT-PCR assays for the rapid pathotyping of type I avian paramyxovirus (APMV-1)

Newcastle disease (ND) caused by virulent avian paramyxovirus type I (APMV-1) is a WOAH and EU listed disease affecting poultry worldwide. ND exhibits different clinical manifestations that may either be neurological, respiratory and/or gastrointestinal, accompanied by high mortality. In contrast, mild or subclinical forms are generally caused by lentogenic APMV-1 and are not subject to notification. The rapid discrimination of virulent and avirulent viruses is paramount to limit the spread of virulent APMV-1. The appropriateness of molecular methods for APMV-1 pathotyping is often hampered by the high genetic variability of these viruses that affects sensitivity and inclusivity. This work presents a new array of real-time RT-PCR (RT-qPCR) assays that enable the identification of virulent and avirulent viruses in dual mode, i.e., through pathotype-specific probes and subsequent Sanger sequencing of the amplification product. Validation was performed according to the WOAH recommendations. Performance indicators on sensitivity, specificity, repeatability and reproducibility yielded favourable results. Reproducibility highlighted the need for assays optimization whenever major changes are made to the procedure. Overall, the new RT-qPCRs showed its ability to detect and pathotype all tested APMV-1 genotypes and its suitability for routine use in clinical samples.

Forensic investigations of religious rituals involving poultry: a case report

Animal victims of human cruelty are receiving increasing attention from the press and society. Veterinary pathologists and civic authorities have a duty not only to elucidate the cause, method and manner of death but also to address the motivation behind a case. Poultry are commonly used as offering to gods in Santería rituals (ebós). Only a few cases have been reported in scientific journals, in contrast with the number of cases described in the media. Here, a hen and a cockerel (Gallus domesticus) were submitted to the VISAVET Health Surveillance Centre for autopsy, which comprised macroscopic and histological studies and microbiological testing for Chlamydia psittaci, avian orthoavulavirus 1 (Newcastle disease virus), West Nile virus and avian influenza virus. The carcasses were in an active decay stage of decomposition, containing larvae of Lucilia eximia. Both animals had been decapitated and haemorrhages in the cutting region were observed histologically. Post-mortem burns were also observed. To the best of the authors' knowledge, this is the first post-mortem description of lesions in a domestic avian species due to religious rituals. European Union and Spanish forensic practitioners should be aware that these ritual sacrifices occur in some European countries. Moreover, future European and national legislation updates should consider this type of animal abuse.

Superior Efficacy of Apathogenic Genotype I (V4) over Lentogenic Genotype II (LaSota) Live Vaccines against Newcastle Disease Virus Genotype VII.1.1 in Pathogen-Associated Molecular Pattern-H9N2 Vaccinated Broiler Chickens

A comparison of the efficacy of apathogenic genotype I (V4) and lentogenic genotype II (LaSota) strains of live Newcastle disease virus (NDV) vaccines was performed following vaccination with pathogen-associated molecular pattern (PAMP) H9N2 avian influenza vaccine and challenge with velogenic NDV genotype VII.1.1 (vNDV-VII.1.1). Eight groups (Gs) of day-old chicks were used (n = 25). Groups 1-4 received a single dose of PAMP-H9N2 subcutaneously, while Gs (1, 5) and (2, 6) received eye drops of V4 and LaSota, respectively, as two doses. All Gs, except for 4 and 8, were intramuscularly challenged with vNDV-VII.1.1 at 28 days of age. No signs were detected in Gs 1, 5, 4, and 8. The mortality rates were 0% in Gs 1, 4, 5, and 8; 40% in G2; 46.66% in G6; and 100% in Gs 3 and 7. Lesions were recorded as minimal in Gs 1 and 5, but mild to moderate in Gs 2 and 6. The lowest significant viral shedding was detected in Gs 1, 2, and 5. In conclusion, two successive vaccinations of broilers with a live V4 NDV vaccine provided higher protection against vNDV-VII.1.1 challenge than LaSota. PAMP-H9N2 with live NDV vaccines induced more protection than the live vaccine alone.

Virulent Newcastle disease virus genotypes V.3, VII.2, and XIII.1.1 and their coinfections with infectious bronchitis viruses and other avian pathogens in backyard chickens in Tanzania

Oropharyngeal (OP) and cloacal (CL) swabs from 2049 adult backyard chickens collected at 12 live bird markets, two each in Arusha, Dar es Salaam, Iringa, Mbeya, Morogoro and Tanga regions of Tanzania were screened for Newcastle disease virus (NDV) using reverse transcription real-time PCR (rRT-PCR). The virus was confirmed in 25.23% of the birds (n = 517; rRT-PCR CT ≤ 30), with the highest positivity rates observed in birds from Dar es Salaam region with higher prevalence during the dry season (September-November 2018) compared to the rainy season (January and April-May 2019). Next-generation sequencing of OP/CL samples of 20 out of 32 birds that had high amounts of viral RNAs (CT ≤ 25) resulted in the assembly of 18 complete and two partial genome sequences (15,192 bp and 15,045-15,190 bp in length, respectively) of NDV sub-genotypes V.3, VII.2 and XIII.1.1 (n = 1, 13 and 4 strains, respectively). Two birds had mixed NDV infections (V.3/VII.2 and VII.2/XIII.1.1), and nine were coinfected with viruses of families Astroviridae, Coronaviridae, Orthomyxoviridae, Picornaviridae, Pneumoviridae, and Reoviridae. Of the coinfecting viruses, complete genome sequences of two avastroviruses (a recombinant chicken astrovirus antigenic group-Aii and avian nephritis virus genogroup-5) and two infectious bronchitis viruses (a turkey coronavirus-like recombinant and a GI-19 virus) were determined. The fusion (F) protein F1/F2 cleavage sites of the Tanzanian NDVs have the consensus motifs 112 RRRKR↓F 117 (VII.2 strains) and 112 RRQKR↓F 117 (V.3 and XIII.1.1 strains) consistent with virulent virus; virulence was confirmed by intracerebral pathogenicity index scores of 1.66-1.88 in 1-day-old chicks using nine of the 20 isolates. Phylogenetically, the complete F-gene and full genome sequences regionally cluster the Tanzanian NDVs with, but distinctly from, other strains previously reported in eastern and southern African countries. These data contribute to the understanding of NDV epidemiology in Tanzania and the region.

Toll-like Receptor Ligands Enhance Vaccine Efficacy against a Virulent Newcastle Disease Virus Challenge in Chickens

To enhance the efficacy of the current Newcastle disease vaccine, we have selected potential adjuvants that target well-characterized pattern recognition receptors: the toll-like receptors (TLRs). Imiquimod is a small-molecule activator of TLR7, which is a sensor of dsDNA. ODN-1826 is a mimetic of CpG DNA and ligates TLR21 (a chicken homologue of TLR9 in mammals). The activation of TLRs leads to antiviral responses, including the induction of type I interferons (IFNs). In this study, birds were vaccinated intranasally with a live LaSota strain with or without imiquimod or ODN-1826 (50 µg/bird). Two weeks after vaccination, the birds were challenged with a virulent Newcastle disease virus (chicken/CA/212676/2002). Both adjuvants (imiquimod or ODN-1826) induced higher and more uniform antibody titers among vaccinated birds compared with the live vaccine-alone group. In addition, adjuvanted vaccines demonstrated greater protective efficacy in terms of the reduction in virus-shedding titer and the number of birds shedding the challenge virus at 2 and 4 days post-challenge. A differential expression of antiviral and immune-related genes was observed among groups from tissues (Harderian gland, trachea, cecal tonsil, and spleen) collected 1 and 3 days after treatment. These results demonstrate the potential of TLR-targeted adjuvants as mucosal vaccine enhancers and warrant a further characterization of immune correlates and optimization for efficacy.

Evaluation of inactivated avian influenza virus and Newcastle disease virus bivalent vaccination program against newly circulated H5N8 and NDV strains

Avian influenza virus (AIV) and Newcastle disease virus (NDV) are respiratory illness syndromes that have recently been detected in vaccinated flocks and are causing major financial losses in the chicken farming industry. The objective was to evaluate the efficacy of Valley Vac H5Plus NDVg7 vaccine in protecting chickens against the H5N8 and NDV strains that have recently been circulating in comparison with the efficacy of the commercially available bivalent H5+ND7 vaccine. In contrast to the H5+ND7 vaccine, which was made of genetically distinct H5N8/2018 clade 2.3.4.4b genotype group (G5), H9N2/2016, H5N1/2017, and genetically comparable NDV genotype VII 1.1/2019 of the recently circulating challenge viruses, the Valley Vac H5Plus NDVg7 vaccine consisted of the recently isolated (RG HPAI H5N1 AIV/2015 Clade 2.2.1.2, RG HPAIV H5N8/2020 Clade 2.3.4.4b genotype group 6 (G6), and NDV genotype VII 1.1/2012) which were genetically similar to challenged strains. To determine the effectiveness of the Valley Vac H5Plus NDVg7 vaccine, a total of 70-day-old commercial chicks were divided into 7 groups of 10 birds each. Groups (G1 and G4) received Valley Vac H5Plus NDVg7 vaccine. Groups (G2 and G5) groups received commercial H5+ND7 vaccine. While groups (G3 and G6) were kept nonvaccinated, and group (G7) was kept as a nonchallenged and nonvaccinated. After 3-wk post vaccination (WPV), groups G1, G2, and G3 were challenged with A/Duck/ Egypt/SMG4/2019(H5N8) genotype G6. On the other hand, groups G4, G5, G6 were challenged with NDV/EGYPT/18629F/2018 genotype VII 1.1 with an intranasal injection of 0.1 mL. Antibody titer was calculated at the first 3 wk after vaccination, and the viral shedding titer was calculated at 3-, 5-, and 7-days post challenge. Mortality and morbidity rates were monitored daily during the experiment, and for the first 10 d after the challenge, to provide an estimate of the protection rate. The results showed that a single dosage of 0.5 mL per bird of Valley Vac H5Plus NDVg7 vaccine provides 80% protection against both H5N8 and NDV, compared to the bivalent H5+ND7 vaccine, which provided 20 and 80% protection against H5N8 and NDV, respectively. In addition, 0.5 mL per bird of Valley Vac H5Plus NDVg7 vaccine produced a greater immune response against both viruses than commercial vaccination at 1 to 3 WPV with a significant difference at 1 WPV for H5N8 and a comparatively higher immune response for NDV. Furthermore, it reduced virus shedding of H5N8 on the third, fifth, seventh, and tenth days lower than H5+ND7 vaccine with a significant difference on the third day for H5N8 and relatively lower than bivalent H5+ND7 vaccine for NDV with a significant difference on the fifth day. The Valley vaccinated group demonstrated more tissue intactness compared to the commercially vaccinated group against the H5N8 challenge, however the bivalent commercially vaccinated group showed the similar level of tissue integrity against NDV. In conclusion, Valley Vac H5Plus NDVg7  that contains the  genetically similar strain to recently circulating challenged virus (H5N8 genotype G6) provided better protection with greater immune response and decreased the amount of virus shed against H5N8 genotype G6 and showed less histopathological alteration than the commercial bivalent H5+ND7 vaccine that contain genetically distinct (H5N8 genotype G5). However the Valley Vac H5Plus NDVg7 provided the same protection with relatively high immune response and  relatively decreased the amount of virus shed and showed equal tissue integrity than the commercial bivalent H5+ND7 vaccine against NDV genotype VII 1.1 that contain the same genotype of NDV genotype VII 1.1.

Detection and molecular characterization of virulent Newcastle disease virus (subgenotype VII.2) in broiler chickens in Northern Vietnam

Background and Aim

Newcastle disease (ND) is a major viral disease of poultry worldwide. However, data on the molecular characterization of Newcastle disease virus (NDV) in Vietnam are limited. This study aimed to identify the molecular characteristics of NDV strains from the vaccinated chickens farmed in Northern Vietnam.

Materials and Methods

We used reverse-transcription polymerase chain reaction (PCR), sequencing and phylogenetic analysis to characterize NDV strains from vaccinated chicken farms in Northern Vietnam.

Results

Seven out of 72 (9.7%) chicken tissue samples collected from seven chicken farms in the four cities/provinces in northern Vietnam were positive for the NDV genome by PCR method. The complete sequences of the fusion (F) and hemagglutinin-neuraminidase (HN) genes of NDVs isolated in the North of Vietnam from 2021 to 2022 were further evaluated. The results indicated that all seven Vietnamese isolates obtained were reported as virulent NDV strains with the amino acid (AA) sequence of the F0 protein proteolytic cleavage site motif (112RRRKRF117). Phylogenetic analysis revealed that they were grouped with other NDV class II from subgenotype VII.2, including the two previous Vietnamese NDV (2015), the Chinese (2017), and Southern African (2013) NDV strains. In addition, some AA substitutions were observed in the neutralizing epitopes of the F and HN proteins of the current Vietnamese NDV strains.

Conclusion

The present findings provide useful information for future studies of the evolution of NDVs and improve strategies for ND-controlling programs in Vietnam.

Molecular Characterization of Complete Genome Sequence of an Avian Coronavirus Identified in a Backyard Chicken from Tanzania

A complete genome sequence of an avian coronavirus (AvCoV; 27,663 bp excluding 3' poly(A) tail) was determined using nontargeted next-generation sequencing (NGS) of an oropharyngeal swab from a backyard chicken in a live bird market in Arusha, Tanzania. The open reading frames (ORFs) of the Tanzanian strain TZ/CA127/19 are organized as typical of gammaCoVs (Coronaviridae family): 5'UTR-[ORFs 1a/1b encoding replicase complex (Rep1ab) non-structural peptides nsp2-16]-[spike (S) protein]-[ORFs 3a/3b]-[small envelop (E) protein]-[membrane (M) protein]-[ORFs 4a/4c]-[ORFs 5a/5b]-[nucleocapsid (N) protein]-[ORF6b]-3'UTR. The structural (S, E, M and N) and Rep1ab proteins of TZ/CA127/19 contain features typically conserved in AvCoVs, including the cleavage sites and functional motifs in Rep1ab and S. Its genome backbone (non-spike region) is closest to Asian GI-7 and GI-19 infectious bronchitis viruses (IBVs) with 87.2-89.7% nucleotide (nt) identities, but it has a S gene closest (98.9% nt identity) to the recombinant strain ck/CN/ahysx-1/16. Its 3a, 3b E and 4c sequences are closest to the duck CoV strain DK/GD/27/14 at 99.43%, 100%, 99.65% and 99.38% nt identities, respectively. Whereas its S gene phylogenetically cluster with North American TCoVs and French guineafowl COVs, all other viral genes group monophyletically with Eurasian GI-7/GI-19 IBVs and Chinese recombinant AvCoVs. Detection of a 4445 nt-long recombinant fragment with breakpoints at positions 19,961 and 24,405 (C- and N-terminus of nsp16 and E, respectively) strongly suggested that TZ/CA127/19 acquired its genome backbone from an LX4-type (GI-19) field strain via recombination with an unknown AvCoV. This is the first report of AvCoV in Tanzania and leaves unanswered the questions of its emergence and the biological significance.

Prevalence of major infectious diseases in backyard chickens from rural markets in Morocco

Background and Aim

Raising backyard chickens is a common practice in Morocco, mainly in rural or periurban areas. Constraints due to devastating avian diseases have been recognized as a major limiting factor in backyard poultry production. Consequently, these flocks could potentially be implicated as reservoirs for poultry diseases. However, there is a considerable lack of information on disease prevalence in this production system, and the risk represented by these small flocks remains under debate. This study aimed to estimate the seroprevalence and identify related risk factors of a range of bacterial and viral pathogens of outstanding importance for the economy and public health in backyard poultry in Morocco.

Materials and Methods

A total of 712 sera samples and 258 cloacal swabs were collected from 712 backyard chickens from 15 rural markets in the Khemisset and Skhirat-Temara provinces. None of the sampled chickens received any vaccination. Sera samples were screened for antibodies against Newcastle disease virus (NDV) and low pathogenic avian influenza H9N2 subtype (LPAI H9N2) using a hemagglutination-inhibition test, against bursal infectious disease virus (IBDV) and infectious bronchitis virus (IBV) using enzyme-linked immunosorbent assay, and against Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) using a rapid serum agglutination test. Swab samples were compiled into 86 pools and submitted for molecular detection using real-time reverse-transcription-polymerase chain reaction (RT-PCR).

Results

The seroprevalences in backyard chickens for NDV, LPAI H9N2, IBDV, IBV, MG, and MS were 52.1% (371/712), 63.5% (452/712), 84.7% (603/712), 82.2% (585/712), 58% (413/712), and 74.8% (533/712), respectively. Based on the RT-PCR results, 2.3% (2/86), 62.8% (54/86), 2.3% (2/86), 63.9% (55/86), 40.7% (35/86), and 29.1% (25/86) of the pools were positive for NDV, H9N2 LPAI, IBDV, IBV, MG, and MS, respectively. Multiple coinfections (H9N2-IBV-MG), (H9N2-IBV-MS), or (IBV-MG-MS) were observed in 15.1%, 8.5%, and 8.5% of the tested samples, respectively.

Conclusion

The results show that backyard chicken flocks and rural markets have the potential to serve as reservoirs or amplifiers for poultry pathogens and could pose a risk to the commercial poultry sector. This highlights the need for a comprehensive and adapted vaccination plan for backyard chickens, and extension of efforts to increase flock owners' awareness of avian diseases and incite the implementation of biosecurity measures at the farm level.

Composting: A biosecurity measure to maximize the benefit of broilers̕ litter

Objective

This study was conducted to evaluate the effect of composting on the count of Salmonella spp., Clostridium perfringens, and New Castle virus (NDV) isolated from broilers' litter. Moreover, to verify the impact of compost thermal stress on the expression of thermal genes harbored in the isolated bacteria.

Materials and Methods

The prevalence of enteric aerobic and anaerobic infections by Salmonella spp., C. perfringens, and viral infections by NDV were investigated in litter samples collected from 100 broiler flocks by conventional methods and polymerase chain reaction.

Results

The samples were positive for Salmonella spp., C. perfringens, and NDV, with prevalence rates of 60%, 55%, and 30%, respectively. An experiment to study the effect of compost on the microbiological quality of litter was applied using five compost heaps with an initial average count of Salmonella typhimurium (3.2 × 105CFU CFU/gm), C. perfringens (6.4 × 105 CFU/gm), and an average titer NDV (105.5 embryo infectious dose50/gm). The microbiological count of heaps after 15 days of composting revealed a reduction in the count of S. typhimurium and C. perfringens by 4 log10 CFU/gm and 3 log10 CFU/gm, respectively. Moreover, the hemagglutinating test revealed no detection of NDV after 15 days of composting. A high degree of downregulation of expression of the thermal genes, dnaK in S. typhimurium isolates and cpe gene in C. perfringens isolates, was detected by quantitative reverse transcription PCR.

Conclusion

The reduction of pathogen counts, the simplicity, and the low cost associated with composting for only 15 days advocate the recommendation for raising awareness of composting as a routine biosecurity measure to prevent the spreading of infection and promote its safe use in agribusiness.

Infectious agents present in monk parakeet (Myiopsitta monachus) and rose-ringed parakeet (Psittacula krameri) invasive species in the parks of Madrid and Seville, Spain

Introduction

The introduction of invasive species into an ecosystem could result in biodiversity loss and the spread of infectious agents that could cause re-emergent or emergent zoonotic diseases. Monk parakeets (Myiopsitta monachus) and rose-ringed parakeets (Psittacula krameri) are considered widespread invasive exotic species in urban habitats from the Iberian Peninsula. The aim of this study was to assess the presence of relevant infectious agents in wild parakeets captured in urban parks in Madrid and Seville (Spain).

Methods

A total of 81 cloacal samples were collected and analysed using molecular techniques.

Results

The prevalence of infectious agents varied between parakeet species: 9.5% of monk parakeets and 15% of rose-ringed parakeets were positive for enteropathogenic E. coli (EPEC), 13.3% of rose-ringed parakeets for avian influenza virus (AIV), 3.3% of rose-ringed parakeets for Newcastle disease virus (NDV), and a 23.8% of monk parakeets for Chlamydia psittaci.

Discussion

All C. psittaci-identified isolates were classified as B, E, or E/B genotypes, indicating transmission from wild urban pigeons to parakeets. These results highlight the need for monitoring parakeet populations due to the implications for human and animal health.

Scavengers as Prospective Sentinels of Viral Diversity: the Snowy Sheathbill Virome as a Potential Tool for Monitoring Virus Circulation, Lessons from Two Antarctic Expeditions

Antarctica is a unique environment due to its extreme meteorological and geological conditions. In addition to this, its relative isolation from human influences has kept it undisturbed. This renders our limited understanding of its fauna and its associated microbial and viral communities a relevant knowledge gap to fill. This includes members of the order Charadriiformes such as snowy sheathbills. They are opportunistic predator/scavenger birds distributed on Antarctic and sub-Antarctic islands that are in frequent contact with other bird and mammal species. This makes them an interesting species for surveillance studies due to their high potential for the acquisition and transport of viruses. In this study, we performed whole-virome and targeted viral surveillance for coronaviruses, paramyxoviruses, and influenza viruses in snowy sheathbills from two locations, the Antarctic Peninsula and South Shetland. Our results suggest the potential role of this species as a sentinel for this region. We highlight the discovery of two human viruses, a member of the genus Sapovirus GII and a gammaherpesvirus, and a virus previously described in marine mammals. Here, we provide insight into a complex ecological picture. These data highlight the surveillance opportunities provided by Antarctic scavenger birds. IMPORTANCE This article describes whole-virome and targeted viral surveillance for coronaviruses, paramyxoviruses, and influenza viruses in snowy sheathbills from the Antarctic Peninsula and South Shetland. Our results suggest an important role of this species as a sentinel for this region. This species' RNA virome showcased a diversity of viruses likely tied to its interactions with assorted Antarctic fauna. We highlight the discovery of two viruses of likely human origin, one with an intestinal impact and another with oncogenic potential. Analysis of this data set detected a variety of viruses tied to various sources (from crustaceans to nonhuman mammals), depicting a complex viral landscape for this scavenger species.

Simultaneous Expression of Chicken Granulocyte Monocyte Colony-Stimulating Factor and the Hemagglutinin-Neuraminidase Epitope of the Virulent Newcastle Disease Virus Genotype VII C22 Strain in a Functional Synthetic Recombinant Adenovirus as a Genotype-Matched Vaccine with Potential Antiviral Activity

When it comes to the prevention of clinical signs and mortality associated with infection of the Newcastle disease virus (NDV), vaccination has been very effective. However, recent evidence has proven that more highly virulent strains are emerging that bypass existing immune protection and pose a serious threat to the global poultry industry. Here, a novel rescued adenovirus 5-coexpressed chicken granulocyte monocyte colony-stimulating factor (ChGM-CSF) bio-adjuvant and C22-hemagglutinin-neuraminidase (HN) boosted chickens' immunological genetic resistance and thus improved the immunological effectiveness of the critical new-generation vaccine in vitro and in vivo. Accordingly, the hemagglutination inhibition (HI) titers (log2) of the recombinant adenovirus (rAdv)-ChGM-CSF-HN-immunized chickens had greater, more persistent, and longer-lasting NDV-specific antibodies than the La Sota and rAdv-HN-inoculated birds. Moreover, humoral and adaptive immunological conditions were shown to be in harmony after rAdv-ChGM-CSF-HN inoculation and uniformly enhanced the expression of alpha interferon (IFN-α), IFN-β, IFN-γ, interleukin-1β (IL-1β), IL-2, IL-16, IL-18, and IL-22. Postchallenge, the control challenge (CC), wild-type adenovirus (wtAdv), and rAdv-ChGM-CSF groups developed unique NDV clinical manifestations, significant viral shedding, high tissue viral loads, gross and microscopic lesions, and 100% mortality within 7 days. The La Sota, rAdv-HN, and rAdv-ChGM-CSF-HN groups were healthy and had 100% survival rates. The rAdv-ChGM-CSF-HN group swiftly regulated and stopped viral shedding and had lower tissue viral loads than all groups at 5 days postchallenge (dpc). Thus, the antiviral activity of ChGM-CSF offered robust immune protection in the face of challenge and reduced viral replication convincingly. Our advance innovation concepts, combining ChGM-CSF with a field-circulating strain epitope, could lead to the development of a safe, genotype-matched, universal transgenic vaccine that could eradicate the disease globally, reducing poverty and food insecurity. IMPORTANCE We studied the biological characterization of the developed functional synthetic recombinant adenoviruses, which showed a high degree of safety, thermostability, and genetic stability for up to 20 passages. It was demonstrated through both in vitro and in vivo testing that the immunogenicity of the proposed vaccine, which uses the T2A peptide from the Thosea asigna virus capsid protein supported by glycine and serine, helps with efficiency to generate a multicistronic vector, enables expression of two functional proteins in rAdv-ChGM-CSF-HN, and is superior to that of comparable vaccines. Additionally, adenovirus can be used to produce vaccines matching the virulent field-circulating strain epitope. Because there is no preexisting human adenoviral immunity detected in animals, the potency of adenoviral vaccines looks promising. Also, it ensures that the living vector does not carry the resistance gene that codes for the kanamycin antibiotic. Accordingly, a human recombinant adenoviral vaccine that has undergone biological improvements is beneficial and important.

Single-Cell Transcriptome Atlas of Newcastle Disease Virus in Chickens Both In Vitro and In Vivo

Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. We characterized the NDV target cell types in the chicken lung at the single-cell transcriptome level and classified cells into five known and two unknown cell types. The five known cell types are the targets of NDV in the lungs with virus RNA detected. Different paths of infection in the putative trajectories of NDV infection were distinguished between in vivo and in vitro, or between virulent Herts/33 strain and nonvirulent LaSota strain. Gene expression patterns and the interferon (IFN) response in different putative trajectories were demonstrated. IFN responses were elevated in vivo, especially in myeloid and endothelial cells. We distinguished the virus-infected and non-infected cells, and the Toll-like receptor signaling pathway was the main pathway after virus infection. Cell-cell communication analysis revealed the potential cell surface receptor-ligand of NDV. Our data provide a rich resource for understanding NDV pathogenesis and open the way to interventions specifically targeting infected cells. IMPORTANCE Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. Our results open the way to interventions specifically targeting infected cells, suggest principles of virus-host interactions applicable to NDV and other similar pathogens, and highlight the potential for simultaneous single-cell measurements of both host and viral transcriptomes for delineating a comprehensive map of infection in vitro and in vivo. Therefore, this study can be a useful resource for the further investigation and understanding of NDV.

Analysis of Avian Orthoavulavirus 1 Detected in the Russian Federation between 2017 and 2021

Newcastle disease virus (NDV, Avian orthoavulavirus type 1, AOAV-1) is a contagious high-impact poultry pathogen with infections detected worldwide. In the present study, 19,500 clinical samples from wild bird species and poultry collected from 28 regions of Russia between 2017 and 2021 were screened for the presence of the AOAV-1 genome. NDV RNA was detected in 15 samples from wild birds and 63 samples from poultry. All isolates were screened for a partial sequence of the fusion (F) gene that included the cleavage site. Phylogenetic analysis demonstrated that lentogenic AOAV-1 I.1.1, I.1.2.1, and II genotypes were dominant among vaccine-like viruses in the territory of the Russian Federation. A vaccine-like virus with a mutated cleavage site (112-RKQGR^L-117) was detected in turkeys. Among the virulent AOAV-1 strains, viruses of the XXI.1.1, VII.1.1, and VII.2 genotypes were identified. The cleavage site of viruses of the XXI.1.1 genotype had a 112-KRQKR^F-117 amino acid sequence. The cleavage site of viruses with VII.1.1 and VII.2 genotypes had a 112-RRQKR^F-117 amino acid sequence. The data collected by the present study demonstrate the distribution and dominance of the virulent VII.1.1 genotype in the Russian Federation between 2017 and 2021.

Vaccine Interaction and Protection against Virulent Avian Metapneumovirus (aMPV) Challenge after Combined Administration of Newcastle Disease and aMPV Live Vaccines to Day-Old Turkeys

Newcastle disease virus (NDV) and avian metapneumovirus (aMPV) are among the most impactful pathogens affecting the turkey industry. Since turkeys are routinely immunized against both diseases, the hatchery administration of the combined respective live vaccines would offer remarkable practical advantages. However, the compatibility of NDV and aMPV vaccines has not yet been experimentally demonstrated in this species. To address this issue, an aMPV subtype B live vaccine was administered to day-old poults either alone or in combination with one of two different ND vaccines. The birds were then challenged with a virulent aMPV subtype B strain, clinical signs were recorded and aMPV and NDV vaccine replication and humoral immune response were assessed. All results supported the absence of any interference hampering protection against aMPV, with no significant differences in terms of clinical scoring. In addition, the mean aMPV vaccine viral titers and antibody titers measured in the dual vaccinated groups were comparable or even higher than in the group vaccinated solely against aMPV. Lastly, based on the NDV viral and antibody titers, the combined aMPV and NDV vaccination does not seem to interfere with protection against NDV, although further studies involving an actual ND challenge will be necessary to fully demonstrate this hypothesis.

Improvement of a Real-Time Reverse Transcription–Polymerase Chain Reaction Assay for the Sensitive Detection of the F Gene of Avian Orthoavulavirus-1 (AOAV-1)

Avian orthoavulavirus-1 (AOAV-1) is the causative agent of Newcastle disease in poultry. This highly infectious disease causes large economic losses annually and worldwide. AOAV-1 does not only infect poultry, but it has a very broad host range and has been detected in over 230 bird species to date. A distinct group of viral strains within AOAV-1 are pigeon-adapted strains, also named pigeon paramyxovirus-1 (PPMV-1). AOAV-1 is transmitted through the feces of infected birds and secretions from the nasal and oral cavities and eyes. It is worth mentioning that wild birds can transmit the virus to captive birds, especially feral pigeons to poultry. Therefore, early and sensitive detection of this virus—including the monitoring of pigeons—is of utmost importance. A variety of molecular methods for the detection of AOAV-1 already exist, but the detection of the F gene cleavage site of currently circulating PPMV-1 strains has not proven to be particularly sensitive or suitable. As presented here, by modifying the primers and probe of an already established real-time reverse-transcription PCR, the sensitivity could be increased, allowing for a more reliable detection of the AOAV-1 F gene cleavage site. Furthermore, it becomes clear how important it is to constantly monitor and, if necessary, adapt existing diagnostic procedures.

Discovery of Avian Paramyxoviruses APMV-1 and APMV-6 in Shorebirds and Waterfowl in Southern Ukraine

Emerging RNA virus infections are a growing concern among domestic poultry industries due to the severe impact they can have on flock health and economic livelihoods. Avian paramyxoviruses (APMV; avulaviruses, AaV) are pathogenic, negative-sense RNA viruses that cause serious infections in the respiratory and central nervous systems. APMV was detected in multiple avian species during the 2017 wild bird migration season in Ukraine and studied using PCR, virus isolation, and sequencing. Of 4090 wild bird samples collected, mostly from southern Ukraine, eleven isolates were grown in ovo and identified for APMV serotype by hemagglutinin inhibition test as: APMV-1, APMV-4, APMV-6, and APMV-7. To build One Health's capacity to characterize APMV virulence and analyze the potential risks of spillover to immunologically naïve populations, we sequenced virus genomes in veterinary research labs in Ukraine using a nanopore (MinION) platform. RNA was extracted and amplified using a multiplex tiling primer approach to specifically capture full-length APMV-1 (n = 5) and APMV-6 (n = 2) genomes at high read depth. All APMV-1 and APMV-6 fusion (F) proteins possessed a monobasic cleavage site, suggesting these APMVs were likely low virulence, annually circulating strains. Utilization of this low-cost method will identify gaps in viral evolution and circulation in this understudied but important critical region for Eurasia.

Genome Sequencing and Characterization of an Avian Orthoavulavirus 1 VG/GA-like Isolate with a Unique Fusion Cleavage Site Motif

A complete genome sequence of a VG/GA -like strain of avian orthoavulavirus 1 (AOAV-1) was identified by nontargeted next-generation sequencing of an oropharyngeal swab sample collected from a carcass of a 12-mo-old backyard chicken. The isolate has a fusion (F) protein cleavage site motif consistent with a low virulent AOAV-1, but it has a unique motif with phenylalanine at position 117 (¹¹²G-R-Q-G-R↓F¹¹⁷), which is typical for virulent AOAV-1 strains. The one nucleotide difference at the cleavage site compared to other low-virulence viruses made the isolate detectable by F-gene-specific real-time reverse transcription-PCR (rRT-PCR) developed as a diagnostic test to specifically detect virulent strains. The mean death time determined in eggs and intracerebral pathogenicity index determined in chickens classified the isolate as lentogenic. This is the first report of a lentogenic VG/GA-like virus with a phenylalanine residue at position 117 of the F protein cleavage site in the United States. In addition to concern for potential pathogenic shift of the virus through additional changes at the cleavage site, our finding warrants increased awareness of diagnosticians of potential false positive F-gene rRT-PCR tests.

Aptamer-Assisted Proximity Ligation Assay for Sensitive Detection of Infectious Bronchitis Coronavirus

Infectious bronchitis virus (IBV) is a coronavirus responsible for major health problems in the poultry industry. New virus strains continue to appear, causing large economic losses. To develop a rapid and accurate new quantitative assay for diagnosis of the virus without DNA extraction, we selected highly specific single-stranded DNA (ssDNA) aptamers with a high affinity to IBV, using the systematic evolution of ligands by exponential enrichment (SELEX) technology for aptamer screening, followed by high-throughput sequencing technology. Two of these aptamers, AptIBV5 and AptIBV2, were used to establish homogenous and solid-phase proximity ligation assays (PLAs). The developed assays were evaluated for their sensitivity and specificity using collected field samples and then compared to the newly developed sandwich enzyme-linked aptamer assay (ELAA) and reverse transcription-quantitative PCR (qRT-PCR), as the gold-standard method. The solid-phase PLA showed a lower limit of detection and a broader dynamic range than the two other assays. The developed technique may serve as an alternative assay for the diagnosis of IBV, with the potential to be extended to the detection of other important animal or human viruses. IMPORTANCE Infectious bronchitis virus (IBV) causes high morbidity and mortality and large economic losses in the poultry industry. The virus has the ability to genetically mutate into new IBV strains, causing devastating disease and outbreaks. To better monitor the emergence of this virus, the development of a rapid and highly sensitive diagnostic method should be implemented. For this, we generated aptamers with high affinity and specificity to the IBV in an ssDNA library. Using two high-affinity aptamers, we developed a sandwich ELAA and a very sensitive aptamer-based proximity ligation assay (PLA). The new assay showed high sensitivity and specificity and was used to detect IBV in farm samples. The PLA was compared to the newly developed sandwich ELAA and qRT-PCR, as the gold-standard technique.

Emergence of Highly Pathogenic Avian Influenza A Virus (H5N1) of Clade 2.3.4.4b in Egypt, 2021-2022

Wild migratory birds have the capability to spread avian influenza virus (AIV) over long distances as well as transmit the virus to domestic birds. In this study, swab and tissue samples were obtained from 190 migratory birds during close surveillance in Egypt in response to the recent outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 virus. The collected samples were tested for a variety of AIV subtypes (H5N1, H9N2, H5N8, and H6N2) as well as other pathogens such as NDV, IBV, ILT, IBDV, and WNV. Among all of the tested samples, the HPAI H5N1 virus was found in six samples; the other samples were found to be negative for all of the tested pathogens. The Egyptian HPAI H5N1 strains shared genetic traits with the HPAI H5N1 strains that are currently being reported in Europe, North America, Asia, and Africa in 2021-2022. Whole genome sequencing revealed markers associated with mammalian adaption and virulence traits among different gene segments, similar to those found in HPAI H5N1 strains detected in Europe and Africa. The detection of the HPAI H5N1 strain of clade 2.3.4.4b in wild birds in Egypt underlines the risk of the introduction of this strain into the local poultry population. Hence, there is reason to be vigilant and continue epidemiological and molecular monitoring of the AIV in close proximity to the domestic-wild bird interface.

Psittacid alphaherpesvirus 5 infection in Indian ringneck parakeets in southern California

Four Indian ringneck parakeets (Psittacula krameri; syn. ringneck parrots or rose-ringed parakeets) were submitted by 2 private owners for autopsy following a history of dyspnea and death. Gross findings were varied and included thickening of the left caudal thoracic air sac, white spots throughout the liver, mild dilation of the proventriculus, coelomic effusion, splenomegaly, and pulmonary congestion and edema. Microscopically, the submitted parakeets had significant lesions in the lower respiratory tract, including necrotizing bronchitis, parabronchitis, and interstitial pneumonia with numerous syncytia containing eosinophilic intranuclear inclusions. Electron microscopy of the lungs was compatible with a herpesviral infection and Psittacid alphaherpesvirus 5 (PsAHV5) was detected via PCR and sequencing. There has been inconsistent terminology used with Psittacid alphaherpesvirus 3 and PsAHV5; we attempt here to clarify the reported history of these viruses.

Assessing the Efficacy of Recombinant Newcastle Disease Virus Vaccines (Double-Insert vHVT-IBD-ND and Single-Insert vHVT-ND) Followed by a Vaccination with a Live Newcastle Disease Vaccine Against a Moroccan Velogenic Newcastle Disease Challenge in Commercial Broilers

The advent of turkey herpesvirus (HVT) vector vaccine technology (vHVT) has made a huge improvement in the prevention and control of several poultry diseases. The objective of this study was to compare, under experimental conditions, the protection conferred by different vaccination programs based on an HVT double-insert (infectious bursal disease {IBD] and Newcastle disease [ND]) vector vaccine (vHVT-IBD-ND) and an HVT single-insert (vHVT-ND) vector vaccine followed by a vaccination with a live ND vaccine at Day 1 only or at Days 1 and 14. Commercial broilers were vaccinated by the recombinant ND virus vaccines subcutaneously at 1 day old, in the hatchery, and challenged at 30 days of age using the Moroccan ND virus velogenic viscerotropic JEL strain. The results showed that the tested vaccine induced 95% to 100% clinical protection against mortality and clinical signs. The humoral immune response to vaccination was detected from 3 wk of age using enzyme-linked immunosorbent assay and hemagglutination inhibition tests. ND challenge virus shedding was significantly reduced in the vaccinated birds as compared to controls. Significant reduction of the cloacal shedding suggests that the vHVT-IBD-ND vaccine stimulates actively the immunity against the tested ND challenge virus. No significant differences were found between the vaccination programs based on vHVT-IBD-ND or on vHVT-ND.

Therapeutic efficacy of n-Docosanol against velogenic Newcastle disease virus infection in domestic chickens

INTRODUCTION

The control of Newcastle disease virus (NDV) infection depends solely on vaccination which in most cases is not sufficient to restrain the consequences of such a highly evolving viral disease. Finding out substances for preparing an efficient anti-ND drug would be of high value. n-Docosanol is a saturated fatty alcohol with an inhibitory effect against many enveloped viruses. In this study, we evaluated the therapeutic effect of n-docosanol on NDV infection and shedding in chickens.

METHODS

Chickens infected with a highly virulent NDV were treated with low to high concentrations of n-docosanol (20, 40, and 60 mg/kg body weight) for 4-successive days, once they showed the disease symptoms. Survival and curative rates, virus load, histopathological scoring, and virus shedding were defined.

RESULTS

Symptoms development was found to discontinue 24-72 hours post-treatment. Survival rate in the NDV-infected chickens raised 37.4-53.2% after the treatment. n-Docosanol treatment was also found to significantly reduce virus load in the digestive (26.2-33.9%), respiratory (38.3-63%), nervous (26.7-51.1%), and lymphatic (16.4-29.1%) tissues. Histopathological scoring of NDV lesions revealed prominent rescue effects on the histology of different tissues. Importantly, n-docosanol treatment significantly reduced virus shedding in oropharyngeal discharge and feces thereby allowing the restriction of NDV spread.

CONCLUSION

Our findings suggest n-docosanol as a promising remedy in the control strategy of Newcastle disease in the poultry industry.

Genetic Analyses of Response of Local Ghanaian Tanzanian Chicken Ecotypes to a Natural Challenge with Velogenic Newcastle Disease Virus

Simple Summary

Newcastle disease (ND) is a global threat to poultry production and often has a major impact on chicken welfare and the livelihoods of rural poultry farmers. We exposed unvaccinated Ghanaian and Tanzanian local chicken ecotypes to velogenic Newcastle disease virus strains, and measured response traits to understand the genetic basis of ND. We identified heritable ND response traits and revealed differences in survival between Ghanaian and Tanzanian local chicken ecotype birds. Our findings indicate that velogenic ND resistance could be improved through selective breeding of local chicken ecotypes in regions where the disease is endemic.

Abstract

Newcastle disease is a devastating poultry disease that often causes significant economic losses in poultry in the developing countries of Africa, Asia, as well as South and Central America. Velogenic Newcastle disease virus (NDV) outbreaks are associated with high mortalities, which can threaten household livelihoods, especially in the rural areas, and lead to loss of high-quality proteins in the form of meat and eggs, as well as household purchasing power. In this study, we exposed unvaccinated Ghanaian and Tanzanian chickens of six local ecotypes to velogenic NDV strains, measured NDV response traits, sequenced their DNA on a genotyping-by-sequencing platform, and performed variance component analyses. The collected phenotypes included: growth rates (pre- and post-exposure); lesion scores (gross lesion severity) in the trachea, proventriculus, intestine, and cecal tonsils; natural antibody levels; anti-NDV antibody levels at 7 days post exposure (dpe); tear and cloacal viral load at 2, 4, and 6 dpe; and survival time. Heritability estimates were low to moderate, ranging from 0.11 for average lesion scores to 0.36 for pre-exposure growth rate. Heritability estimates for survival time were 0.23 and 0.27 for the Tanzanian and Ghanaian ecotypes, respectively. Similar heritability estimates were observed when data were analyzed either separately or combined for the two countries. Survival time was genetically negatively correlated with lesion scores and with viral load. Results suggested that response to mesogenic or velogenic NDV of these local chicken ecotypes could be improved by selective breeding. Chickens that are more resilient to velogenic NDV can improve household livelihoods in developing countries.

Screening of Healthy Feral Pigeons (Columba livia domestica) in the City of Zurich Reveals Continuous Circulation of Pigeon Paramyxovirus-1 and a Serious Threat of Transmission to Domestic Poultry

Pigeon paramyxovirus-1 (PPMV-1) is predominantly isolated from pigeons or doves and forms a separate group of viral strains within Avian Orthoavulavirus-1, the causative agent of Newcastle disease in poultry. Since the introduction of PPMV-1 into Europe in 1981, these strains have rapidly spread all over Europe, and are nowadays considered to be enzootic in feral and hobby pigeons (Columba livia domestica). Infections with PPMV-1 can range from asymptomatic to fatal. To assess whether PPMV-1 continuously circulates in healthy feral pigeons, 396 tissue samples of pigeons from the city of Zurich were tested by reverse transcriptase real-time PCR over the period of one year. PPMV-1-RNA was detected in 41 feral pigeons (10.35%), determined as the dominant European genotype VI.2.1.1.2.2. In 38 of the 41 pigeons where organ samples tested positive, PPMV-1-RNA was also detected in either choana or cloaca swabs. There were no significant differences in positivity rates between seasons, age, and sex. The current study shows that feral pigeons without clinical signs of disease can harbour and most likely excrete PPMV-1. Spill-over into free-range holdings of chickens are therefore possible, as observed in a recent outbreak of Newcastle disease in laying hens due to PPMV-1 genotype VI.2.1.1.2.2. in the canton of Zurich in January 2022.

Review detection of Newcastle disease virus

Newcastle disease (ND) is an acute and highly contagious disease caused by the Newcastle disease virus (NDV) infecting poultry, which has caused great harm to the poultry industry around the world. Rapid diagnosis of NDV is important to early treatment and early institution of control measures. In this review, we comprehensively summarize the most recent research into NDV, including historical overview, molecular structure, and infection mechanism. We then focus on detection strategies for NDV, including virus isolation, serological assays (such as hemagglutination and hemagglutination-inhibition tests, enzyme linked immunosorbent assay, reporter virus neutralization test, Immunofluorescence assay, and Immune colloidal gold technique), molecular assays (such as reverse transcription polymerase chain reaction, real-time quantitative PCR, and loop-mediated isothermal amplification) and other assays. The performance of the different serological and molecular biology assays currently available was also analyzed. To conclude, we examine the limitations of currently available strategies for the detection of NDV to lay the groundwork for new detection assays.

Poultry diseases diagnostics models using deep learning

Coccidiosis, Salmonella, and Newcastle are the common poultry diseases that curtail poultry production if they are not detected early. In Tanzania, these diseases are not detected early due to limited access to agricultural support services by poultry farmers. Deep learning techniques have the potential for early diagnosis of these poultry diseases. In this study, a deep Convolutional Neural Network (CNN) model was developed to diagnose poultry diseases by classifying healthy and unhealthy fecal images. Unhealthy fecal images may be symptomatic of Coccidiosis, Salmonella, and Newcastle diseases. We collected 1,255 laboratory-labeled fecal images and fecal samples used in Polymerase Chain Reaction diagnostics to annotate the laboratory-labeled fecal images. We took 6,812 poultry fecal photos using an Open Data Kit. Agricultural support experts annotated the farm-labeled fecal images. Then we used a baseline CNN model, VGG16, InceptionV3, MobileNetV2, and Xception models. We trained models using farm and laboratory-labeled fecal images and then fine-tuned them. The test set used farm-labeled images. The test accuracies results without fine-tuning were 83.06% for the baseline CNN, 85.85% for VGG16, 94.79% for InceptionV3, 87.46% for MobileNetV2, and 88.27% for Xception. Finetuning while freezing the batch normalization layer improved model accuracies, resulting in 95.01% for VGG16, 95.45% for InceptionV3, 98.02% for MobileNetV2, and 98.24% for Xception, with F1 scores for all classifiers above 75% in all four classes. Given the lighter weight of the trained MobileNetV2 and its better ability to generalize, we recommend deploying this model for the early detection of poultry diseases at the farm level.

First isolation of influenza A subtype H5N8 in ostrich: Pathological and genetic characterization

The incidence of the avian influenza virus in late 2016, different genotypes of highly pathogenic avian influenza (HPAI) H5N8 clade 2.3.4.4b have been reported among different domestic and wild bird species. The virus became endemic in the poultry population, causing a considerable economic loss for the poultry industry. This study screened 5 ostrich farms suffering from respiratory signs and mortality rate of the avian influenza virus. A flock of 60-day-old ostriches with a mortality of 90% suffered from depression, loss of appetite, dropped production, and oculo-nasal discharges, with bleeding from natural orifices as a vent. This flock was found positive for avian influenza virus and subtypes as HPAI H5N8 virus. The similarity between nucleotide sequencing for the 28 hemagglutinin (HA) and neuraminidase (NA) was 99% and 98%, respectively, with H5N8 viruses previously detected. The PB2 encoding protein harbor a unique substitution in mammalian marker 627A, which has not been recorded before in previously sequenced H5N8 viruses. Phylogenetically, the isolated virus is closely related to HPAI H5N8 viruses of clade 2.3.4.4b. The detection of the HPAI H5N8 virus in ostrich is highly the need for continuous epidemiological and molecular monitoring of influenza virus spread in other bird species, not only chickens. Ostrich should be included in the annual SunAlliance, for the detection of avian influenza.

Host response to successive challenges with lentogenic and velogenic Newcastle disease virus in local chickens of Ghana

Newcastle disease (ND) is a highly contagious viral disease that constantly threatens poultry production. The velogenic (highly virulent) form of ND inflicts the most damage and can lead to 100% mortality in unvaccinated village chicken flocks. This study sought to characterize responses of local chickens in Ghana after challenging them with lentogenic and velogenic Newcastle disease virus (NDV) strains. At 4 wk of age, chicks were challenged with lentogenic NDV. Traits measured were pre- and post-lentogenic infection growth rates (GR), viral load at 2 and 6 d post-lentogenic infection (DPI), viral clearance rate and antibody levels at 10 DPI. Subsequently, the chickens were naturally exposed to velogenic NDV (vNDV) after anti-NDV antibody titers had waned to levels ≤1:1,700. Body weights and blood samples were again collected for analysis. Finally, chickens were euthanized and lesion scores (LS) across tissues were recorded. Post-velogenic exposure GR; antibody levels at 21 and 34 days post-velogenic exposure (DPE); LS for trachea, proventriculus, intestines, and cecal tonsils; and average LS across tissues were measured. Variance components and heritabilities were estimated for all traits using univariate animal models. Mean pre- and post-lentogenic NDV infection GRs were 6.26 g/day and 7.93 g/day, respectively, but mean post-velogenic NDV exposure GR was −1.96 g/day. Mean lesion scores ranged from 0.52 (trachea) to 1.33 (intestine), with males having significantly higher (P < 0.05) lesion scores compared to females. Heritability estimates for the lentogenic NDV trial traits ranged from moderate (0.23) to high (0.55) whereas those for the vNDV natural exposure trial were very low (≤ 0.08). Therefore, in contrast to the vNDV exposure trial, differences in the traits measured in the lentogenic challenge were more affected by genetics and thus selection for these traits may be more feasible compared to those following vNDV exposure. Our results can form the basis for identifying local chickens with improved resilience in the face of NDV infection for selective breeding to improve productivity.

Comparison between intratumoral and intravenously administered oncolytic virus therapy with Newcastle disease virus in a xenograft murine model for pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a poor clinical prognosis and is usually a metastatic disease. In the last decades, oncolytic viro-immunotherapy has shown a promise as treatment strategy with encouraging results for a variety of tumors. Newcastle Disease Virus (NDV) is an oncolytic virus which selectively infects and damages tumors either by directly killing tumor cells or by promoting an anti-tumor immune response. Several studies have demonstrated that NDV strains with a multi-basic cleavage site (MBCS) in the fusion protein (F) have increased anti-tumor efficacy upon intratumoral injection in murine tumor models. However, intravenous injections, in which the oncolytic virus spreads systemically, could be more beneficial to treat metastasized PDAC in addition to the primary tumor. In this study, we compared the oncolytic efficacy and safety of intratumoral and intravenous injections with NDV containing an MBCS in F (NDV F3aa) in an immune deficient murine xenograft (BxPC3) model for PDAC. In this model, both intratumoral and intravenous injections with NDV F3aa induced anti-tumor efficacy as measured at 10 days after the first injection. Upon intravenous injection virus was detected in some of the tumors, indicating the systemic spread of the virus. Upon both treatments, mice did not display weight loss or abnormalities and treated mice did not secrete virus to the environment. These data demonstrate that intravenous injections of NDV F3aa can be applicable to treat metastasized cancers in immune deficient hosts without inflicting adverse effects.

Genetic Variations among Different Variants of G1-like Avian Influenza H9N2 Viruses and Their Pathogenicity in Chickens

Since it was first discovered, the low pathogenic avian influenza (LPAI) H9N2 subtype has established linages infecting the poultry population globally and has become one of the most prevalent influenza subtypes in domestic poultry. Several different variants and genotypes of LPAI H9N2 viruses have been reported in Egypt, but little is known about their pathogenicity and how they have evolved. In this study, four different Egyptian LPAI H9N2 viruses were genetically and antigenically characterized and compared to representative H9N2 viruses from G1 lineage. Furthermore, the pathogenicity of three genetically distinct Egyptian LPAI H9N2 viruses was assessed by experimental infection in chickens. Whole-genome sequencing revealed that the H9N2 virus of the Egy-2 G1-B lineage (pigeon-like) has become the dominant circulating H9N2 genotype in Egypt since 2016. Considerable variation in virus shedding at day 7 post-infections was detected in infected chickens, but no significant difference in pathogenicity was found between the infected groups. The rapid spread and emergence of new genotypes of the influenza viruses pinpoint the importance of continuous surveillance for the detection of novel reassortant viruses, as well as monitoring the viral evolution.

Surveillance of Class I Newcastle Disease Virus at Live Bird Markets in China and Identification of Variants with Increased Virulence and Replication Capacity

In this study, 232 class I Newcastle disease viruses (NDVs) were identified from multiple bird species at nationwide live bird markets (LBMs) from 2017 to 2019 in China. Phylogenetic analysis indicated that all 232 isolates were clustered into genotype 1.1.2 of class I on the basis of the fusion (F) gene sequences, which were distinct from the genotypes identified in other countries. Most of the isolates (212/232) were shown to have the typical F gene molecular characteristics of class I NDVs, while a few (20/232) contained mutations at the site of the conventional start codon of the F gene, which resulted in open reading frames (ORFs) altered in length. The isolates with ACG, CTA, and ATA mutations showed different levels of increased virulence and replication capacity, suggesting that these viruses may be transitional types during the evolution of class I NDVs from avirulent to virulent. Further evaluation of biological characteristics with recombinant viruses obtained by reverse genetics demonstrated that the ATG located at genomic positions 4523 to 4525 was the authentic start codon in the F gene of class I NDV, and the specific ATA mutations which contributed to the expression of F protein on the surface of infected cells were the key determinants of increased replication capacity and virulence. Interestingly, the mutation at the corresponding site of genotype II LaSota of class II had no effects on the virulence and replication capacity in chickens. Our results suggest that the alteration of virulence and replication capacity caused by specific mutations in the F gene could be a specific characteristic of class I NDVs and indicate the possibility of the emergence of virulent NDVs due to the persistent circulation of class I NDVs. IMPORTANCE The available information on the distribution, genetic diversity, evolution, and biological characteristics of class I Newcastle disease viruses (NDVs) in domestic poultry is currently very limited. Here, identification of class I NDVs at nationwide live bird markets (LBMs) in China was performed and representative isolates were characterized. A widespread distribution of genotype 1.1.2 of class I NDVs was found in multiple bird species at LBMs in China. Though most isolates demonstrated typical molecular characteristics of class I NDVs, a few that contained specific mutations at the site of the conventional start codon of the fusion gene with increased virulence and replication capacity were identified for the first time. Our findings indicate that the virulence of class I NDVs could have evolved, and the widespread transmission and circulation of class I NDVs may represent a potential threat for disease outbreaks in poultry.

Prevalence of Newcastle Disease Virus in Wild and Migratory Birds in Haryana, India

Newcastle disease virus (NDV) can infect approximately 250 avian species and causes highly contagious Newcastle disease (ND) in domestic poultry, leading to huge economic losses. There are three different pathotypes of NDV, i.e., lentogenic, mesogenic, and velogenic. Wild resident (wild) and migratory birds are natural reservoirs of NDV and are believed to play a key role in transmitting the virus to domestic poultry. The present study was conducted to determine the prevalence of NDV in wild and migratory birds in the state of Haryana, India, during two migratory seasons (2018-19 and 2019-20). In total 1379 samples (1368 choanal swabs and 11 tissue samples) were collected from live (n = 1368) or dead birds (n = 4) belonging to 53 different avian species. These samples belonged to apparently healthy (n = 1338), sick (n = 30), and dead (n = 4) birds. All samples were tested for NDV by real-time reverse transcription-PCR using M gene specific primers and probe. Of the 1379 samples, 23 samples from wild birds [Columba livia domestica (n = 12, 52.17%), Pavo cristatus (n = 9, 39.13%), and Psittaciformes (n = 2, 8.69%)] were found positive for NDV. Only one of the 23 samples (from P. cristatus) was positive for F gene, indicating it to be a mesogenic/velogenic strain. These results indicate that both lentogenic and velogenic strains of NDV are circulating in wild birds in Haryana and that further studies are needed to characterize NDV strains from wild/migratory birds and domestic poultry to determine the extent of virus transmission among these populations. This study considers the disease transmission risk from domestic pigeons and parrots to commercial poultry and vice versa, and the results emphasize the need for strict biosecurity strategies to protect commercial poultry in the region.