Pigeon Paramyxovirus Research Articles

Assessment of PPMV-1 Genotype VI Virulence in Pigeons and Chickens and Protective Effectiveness of Paramyxovirus Vaccines in Pigeons.

Pigeon paramyxovirus serotype 1 (PPMV-1), an antigenic and host variant of avian paramyxovirus Newcastle disease virus (NDV), primarily originating from racing pigeons, has become a global panzootic. Egypt uses both inactivated PPMV-1 and conventional NDV vaccines to protect pigeons from disease and mortality. However, the impact of prevalent strains and the effectiveness of available vaccines in pigeons in Egypt are unclear. This study investigates the virulence of PPMV-1 (Pigeon/Egypt/Sharkia-19/2015/KX580988) and evaluates available paramyxovirus vaccines in protecting pigeons against a PPMV-1 challenge. Ten-day-old specific-pathogen-free (SPF) embryonated chicken eggs infected with this strain exhibited a mean death time (MDT) of 86.4 ± 5.88 h. The intracerebral pathogenicity index (ICPI) in day-old chickens was 0.8, while pigeons experienced an ICPI of 0.96 and an intravenous pathogenicity index (IVPI) of 2.11. These findings classify the strain as virulent and velogenic. Experimental infection of pigeons with this PPMV-1 strain at 106 EID50/0.1 mL resulted in a 62.5% mortality rate, displaying nervous and enteric distress. The virus caused extensive lesions in visceral organs, with strong immunohistochemistry signals in all examined organs, indicating the systemic spread of the virus concurrent to its neurotropic and viscerotropic tropism. Furthermore, vaccination using an inactivated PPMV-1 and live NDV LaSota vaccine regimen protected 100% of pigeons against mortality, while with a single NDV LaSota vaccine, it was 62.5%. The PPMV alone or combined with NDV LaSota induced protective levels of haemagglutination inhibition (HI) antibody titres and reduced virus shedding from buccal and cloacal cavities. Based on generalised linear gamma model analysis, both PPMV-1 and NDV LaSota are antigenically comparable by HI. These findings suggest that using both inactivated PPMV-1 (G-VI) and live attenuated NDV (LaSota) vaccines is an effective prophylactic regimen for preventing and controlling PPMV-1 and NDV in pigeons, thereby reducing the risk of interspecies transmission.

RAA-CRISPR/Cas12a-Mediated Rapid, Sensitive, and Onsite Detection of Newcastle Disease in Pigeons.

Pigeon Newcastle disease, caused by pigeon paramyxovirus type 1 (PPMV-1), is a significant infectious disease in pigeons that can result in substantial mortality and poses a severe threat to the pigeon industry. The rapid and accurate onsite diagnosis of pigeon disease is crucial for timely diagnosis and the implementation of effective prevention and control measures. In this study, we established a rapid detection method for PPMV-1 based on recombinase-aided amplification (RAA) and CRISPR/Cas12a. The RAA primers target the conserved regions of the L gene for preamplification in clinical nucleic acid samples, followed by CRISPR/Cas12a detection of the target gene. Visualization could be achieved by combination with a lateral flow dipstick (LFD). This method demonstrated high specificity, showing no cross-reactivity with non-PPMV-1 samples. The sensitivity of the method assessed by fluorescence analysis reached 100 copies/µL, and when it was combined with an LFD, the sensitivity was 103 copies/µL. The constructed RAA-CRISPR/Cas12a-LFD visual detection method was applied to clinical sample testing and was found to enable the rapid and accurate detection of swab samples and tissue specimens. Its sensitivity was consistent with the current gold standard, quantitative real-time PCR results. The RAA-CRISPR/Cas12a-LFD detection method we developed provides a novel approach for the rapid, simple, precise, and specific onsite diagnosis of pigeon Newcastle disease.

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

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

Molecular characteristics and phylogenetic analysis of pigeon paramyxovirus type 1 isolates from pigeon meat farms in Shanghai (2009–2012)

The majority of pigeon paramyxovirus type 1 (PPMV-1) strains are generally non-pathogenic to chickens; however, they can induce severe illness and high mortality rates in pigeons, leading to substantial economic repercussions. The genomes of 11 PPMV-1 isolates from deceased pigeons on meat pigeon farms during passive monitoring from 2009 to 2012 were sequenced and analyzed using polymerase chain reaction and phylogenetic analysis. The complete genome lengths of 11 isolates were approximately 15,192 nucleotides, displaying a consistent gene order of 3′-NP-P-M-F-HN-L-5′. ALL isolates exhibited the characteristic motif of 112RRQKRF117 at the fusion protein cleavage site, which is characteristic of velogenic Newcastle disease virus. Moreover, multiple mutations have been identified within the functional domains of the F and HN proteins, encompassing the fusion peptide, heptad repeat region, transmembrane domains, and neutralizing epitopes. Phylogenetic analysis based on sequences of the F gene unveiled that all isolates clustered within genotype VI in class II. Further classification identified at least two distinct sub-genotypes, with seven isolates classified as sub-genotype VI.2.1.1.2.2, whereas the others were classified as sub-genotype VI.2.1.1.2.1. This study suggests that both sub-genotypes were implicated in severe disease manifestation among meat pigeons, with sub-genotype VI.2.1.1.2.2 displaying an increasing prevalence among Shanghai’s meat pigeon population since 2011. These results emphasize the value of developing pigeon-specific vaccines and molecular diagnostic tools for monitoring and proactively managing potential PPMV-1 outbreaks.

Genetic Characterization, Pathogenicity, and Epidemiology Analysis of Three Sub-Genotype Pigeon Newcastle Disease Virus Strains in China.

Pigeon Newcastle disease (ND) is a serious infectious illness caused by the pigeon Newcastle disease virus (NDV) or Paramyxovirus type 1 (PPMV-1). Genotype VI NDV is a primary factor in ND among Columbiformes (such as pigeons and doves). In a recent study, eight pigeon NDV strains were discovered in various provinces in China. These viruses exhibited mesogenic characteristics based on their MDT and ICPI values. The complete genome sequences of these eight strains showed a 90.40% to 99.19% identity match with reference strains of genotype VI, and a 77.86% to 80.45% identity match with the genotype II vaccine strain. Additionally, analysis of the F gene sequence revealed that these NDV strains were closely associated with sub-genotypes VI.2.2.2, VI.2.1.1.2.1, and VI.2.1.1.2.2. The amino acid sequence at the cleavage site of the F protein indicated virulent characteristics, with the sequences 112KRQKRF117 and 112RRQKRF117 observed. Pigeons infected with these sub-genotype strains had a low survival rate of only 20% to 30%, along with lesions in multiple tissues, highlighting the strong spread and high pathogenicity of these pigeon NDV strains. Molecular epidemiology data from the GenBank database revealed that sub-genotype VI.2.1.1.2.2 strains have been prevalent since 2011. In summary, the findings demonstrate that the prevalence of genotype VI NDV is due to strains from diverse sub-genotypes, with the sub-genotype VI.2.1.1.2.2 strain emerging as the current epidemic strain, highlighting the significance of monitoring pigeon NDV in China.

The TRK-fused gene negatively regulates interferon signaling by inhibiting TBK1 phosphorylation during PPMV-1 infection

TRK-fused gene (TFG, tropomyosin-receptor kinase fused gene) is known to negatively regulate the retinoic acid inducible gene (RIG)-I-like receptor (RLR)-mediated interferon (IFN)-I pathway in human cells, thereby participating in the paramyxovirus infection process. We showed that pigeon paramyxovirus type 1 (PPMV-1) infection significantly upregulates TFG expression in infected cells at an early stage. We speculated that PPMV-1 would inhibit IFN activation by upregulating a negative regulator of the IFN pathway. This hypothesis was proved when TFG protein expression was knocked down by RNAi and the replication level of PPMV-1 virus decreased, which indicated that TFG upregulation in the early infection stage benefit virus replication. We next used the IFN-β promoter reporter system to evaluate the role of the TFG in the IFN pathway. The results showed that the TFG inhibited the IFN-β expression stimulated by RIG-I, MAVS (mitochondrial antiviral signaling protein) and TANK-binding kinase 1 (TBK1), but did not inhibit IFN-β activated by the interferon regulatory transcription factor 3 (IRF3), indicating that TFG may affect the function of TBK1, which play an important role in phosphorylation of the IRF3. Further experiments showed that the TFG inhibited the phosphorylation of TBK1, resulting in IRF3 being unable to be phosphorylated. Subsequent experiments on IFN pathway activation confirmed that the IRF3 phosphorylation level was significantly downregulated after overexpression of TFG, while the IFN-β promoter reporting experiment showed that TFG did not directly inhibit the IFN response activated by IRF3. This confirmed that TFG protein negatively regulates the IFN-β pathway by inhibiting TBK1 phosphorylation.

Severe pigeon paramyxovirus 1 infection in a human case with probable post-COVID-19 condition

ABSTRACT Pigeon paramyxovirus 1 (PPMV-1) is an antigenic host variant of avian paramyxovirus 1. Sporadic outbreaks of PPMV-1 infection have occurred in pigeons in China; however, few cases of human PPMV-1 infection have been reported. The purpose of this article is to report a case of severe human PPMV-1 infection in an individual with probable post-COVID-19 syndrome (long COVID) who presented with rapidly progressing pulmonary infection. The patient was a 66-year-old man who was admitted to the intensive care unit 11 days after onset of pneumonia and recovered 64 days after onset. PPMV-1 was isolated from the patient’s sputum and in cloacal smear samples from domesticated pigeons belonging to the patient’s neighbour. Residual severe acute respiratory syndrome coronavirus 2 was detected in respiratory and anal swab samples from the patient. Sequencing analyses revealed that the PPMV-1 genome belonged to genotype VI.2.1.1.2.2 and had the 112RRQKRF117 motif in the cleavage site of the fusion protein, which is indicative of high virulence. This case of cross-species transmission of PPMV-1 from a pigeon to a human highlights the risk of severe PPMV-1 infection in immunocompromised patients, especially those with long COVID. Enhanced surveillance for increased risk of severe viral infection is warranted in this population.

Rapid detection of pigeon Megrivirus using TaqMan real-time PCR technology

Megriviruses have been identified from fecal samples in wild pigeons in Hong Kong (China) and Hungary. In this study, the genomic sequences of pigeon Megriviruses (PiMeVs) were downloaded from GenBank and compared. Based on the genetic comparison results, a pair of primers and TaqMan probe were designed based on the conserved sequences of the 3C gene (located in the P3 gene coding region), and a TaqMan real-time PCR method (TaqMan-qPCR) was established. The standard curve of the TaqMan-qPCR had an axial intercept of 39.74 and a slope of -3.2475 with a linear correlation (R2) of 1.00 and an efficiency of 103.2%. No cross-amplification signal was found from other pigeon viruses (such as avian influenza virus, pigeon paramyxovirus type I, pigeon torque teno virus, pigeon adenovirus, and pigeon circovirus). The limit of detection concentration was 53.6 copies/μL. The intra- and interassay results were less than 1.0% based on the reproducibility test. Furthermore, field samples investigation by the established TaqMan-qPCR method showed that positive signals can be found from racing pigeon fecal samples and embryos. Thus, our data suggested that this visible TaqMan-qPCR method is sensitive, specific, and reproducible. Moreover, we first confirmed the presence of pigeon Megrivirus infection in racing pigeon embryos, indicating that the virus may be vertically transmitted. This study provides a reference basis for further understanding the epidemiology of PiMeVs.

Isolation, full sequence analysis, and in situ hybridization of pigeon paramyxovirus-1 genotype VI.2.1.1.2.2 from oriental turtle doves (Streptopelia orientalis)

Pigeon paramyxovirus-1 (PPMV-1), a genetic variant of avian paramyxovirus-1 (APMV-1), has been identified in Columbiformes and is the primary cause of diseases in captive and free-ranging pigeons. However, it has also been reported that PPMV-1 can infect chickens naturally and experimentally, thus posing a potential threat to the poultry industry. This study investigated a lethal outbreak of paramyxovirus infection that occurred among 16 oriental turtle doves (Streptopelia orientalis) in a walk-in aviary at a zoo from March to April 2021. Necropsies were performed, and histopathological findings revealed mild to moderate lymphoplasmacytic infiltration in several organs, such as the pancreas, liver, kidneys, and lungs. Reverse transcription polymerase chain reaction (RT-PCR) using formalin-fixed paraffin-embedded tissue blocks, virus isolation from fresh tissue, and in situ hybridization against the fusion (F) protein confirmed the diagnosis for PPMV-1 infection. The isolated strain NTU/C239/21 was fully sequenced by next-generation sequencing, and the results of phylogenetic analyses revealed that the F protein of NTU/C239/21 shared 98.8% nucleotide sequence identity with Pigeon/Taiwan/AHRI121/2017, which was isolated from a feral pigeon in Taiwan. The present study is the first to identify PPMV-1 infection in Streptopelia orientalis and suggests that Streptopelia orientalis may also play an important role in spreading the infection, similar to pigeons in APMV-1 spreading.

Genomic and biological characterization of Pigeon Paramyxovirus Type-1 isolated from Indian pigeons: First report on the six nucleotide insertion in the non-coding region of nucleoprotein gene

Genotypic analysis of Pigeon Paramyxovirus Type-1 (PPMV-1) virus, in corroboration with pathotyping, underpins the knowledge on the occurrence of PPMV-1 mediated Newcastle disease in poultry. In the present study, two PPMV-1 isolates, namely D167 and D168, obtained from feral pigeons of India in the year 2014 were analysed for their genotypic and pathotypic characteristics. Phylogenetic analysis of Fusion (F) gene grouped D167 and D168 under sub-genotypes VI.2.2.2. and VI.2.1.1.2.2. respectively. The separate positioning of these isolates within genotype VI is corroborated with the variation in restriction enzyme sites analysed through virtual restriction mapping. Analysis of FPCS region showed that both D167 and D168 possessed 112RRQKRF117 amino-acid pattern. Intra-cerebral pathogenicity index (ICPI) of D167 and D168 was 1.57 and 1.3, and mean death time (MDT) was 48 and 70 hrs respectively, designating D168 as a mesogenic pathotype, and D167 as a velogenic pathotype. Histopathological analysis of proventriculus, intestine, lungs and spleen of chickens infected with D167 and D168 isolates through intramuscular (I/M), subcutaneous (S/C) and oculo-nasal/oral (O/N) routes of inoculation showed similar severity of tissue damage. This study shows that PPMV-1 isolates belonging to two different sub-genotypes without a common ancestor, can occur together in a particular geographical region. It also shows that PPMV-1 gains virulence in chickens, which needs to be addressed in order to avoid emergence of PPMV-1 as new velogenic variant causing Newcastle disease in chickens.

SURVEY ON THE MOST COMMON DISEASES CIRCULATING AMONG PIGEONS IN THE EASTERN PROVINCE, SAUDI ARABIA

Molecular and microbiological approaches were used to investigate the common circulating pathogens in pigeon flocks. Sixty-nine flocks were investigated for viral, bacterial and parasitic infection evidence, including the histories, clinical signs and lesions. We reported that the seroprevalences of Newcastle disease viruses (NDVs), Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) were 50.57%, 7.25% and 8.69%. respectively; no avian influenza virus (AIV)‒specific antibodies were detected. NDVs and pigeon paramyxoviruses (PPVs) were detected in 40.57% and 15.9%, respectively, of the pigeons. Multiple diseases were the predominant finding, with 60.87% of diseased flocks harboring multifactorial infections of viral, bacterial and parasitic pathogens. Concurrent viral and bacterial infections were reported in 15.94%, and viral and parasitic coinfections were found in 20.29%. Mixed infections of NDV with bacterial and parasitic diseases were detected in 21.74%. Bacterial and mycotic pathogens were detected in 22/69 (31.88%) and 5/69 (7.25%), respectively. Salmonella spp. were only detected in 3/69 (4.35%) of diseased flocks. Parasitic diseases were the most prevalent infections, either as a single infection or concurrently with others. Parasites including Cestoda spp., Ascaris spp., Eimeria spp., Trichomonas gallinae and external parasites(Menopon gallinae, Pseudolynchia canariensis) were reported in 12/69 (17.39%), 10/69 (10.49%), 10/69 (10.49%), 18/69 (26.1%) and 3/69 (4.35%), respectively. We concluded that pigeon flocks harbor many pathogens that may threaten the health of animals and humans; they are serious amplifiers and reservoir hosts of disease and, ultimately, may be serious biological hazards to the intensive poultry production sector and community. Pigeon vaccines should be developed. Strict biosecurity measures should be applied to protect pigeons and commercial poultry flocks. Key words: Pigeon, diseases, PCR, isolation and identification, Saudi Arabia

Biological characterization of isolated pigeon Paramyxovirus-1 and its pathogenicity analysis in SPF chickens

Pigeon paramyxovirus type 1 (PPMV-1) is considered as an antigenic variant of Newcastle Disease leading to high mortality and significant economic losses to the poultry industry. However, the pathogenicity of PPMV-1 to chickens is still unclear. Herein, we reported the biological characterization of the isolated PPMV-1 from the diseased pigeons suspected to Newcastle Disease and studied its pathogenicity in SPF chickens. The phylogenetic tree and evolution distances revealed that the new isolate belonged to a VI.2.1.1.2.2 sub-genotype of NDV. Despite the cleavage motif of the F protein containing the 112RRQKR↓F117 sequence associated with virulent NDV strains, and the value of MDT and ICPI of the isolate showing mesogenic characteristics, the challenge trial showed that the isolate had weak pathogenicity to chickens while causing lesions in multiple tissues and organs in pigeons.

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.

Newcastle disease in pigeon review article

Newcastle disease (ND) is a viral disease of poultry and other bird species like pigeon (Columbi livia), it characterizes as devastating and contagious and it has been distributed worldwide. ND in pigeons is caused by pigeon paramyxovirus type 1(PPMV-1) which is an antigenic and host variant of the avian paramyxovirus serotype 1 (APMV-1), the disease in pigeons is termed paramyxovirosis and cause nervous signs with high mortality usually in the bird with kidneys infected with viscerotropic strains, and neural signs appeared individually. PPMV-1 was initially detected by hemagglutination activity (HA) and confirmed with hemagglutination inhibition assay (HI), and molecular-based techniques. Serological diagnosis of paramyxovirosis is necessary because of the similarity of the PPMV-1 infection with sodium chloride poisoning, pigeon herpes virus infection (PHV), and ornidazole overdose that cause same neurological signs. PPMV-1 infection can be controlled effectively by vaccination by specific vaccines associated with good biosecurity aspect

Genomic and comparative clinico-pathological assessment of two Pakistani pigeon-derived newcastle disease virus sub-genotypes XXI.1.1 and XXI.1.2 isolated in 2017

Pigeon paramyxovirus type-1 (PPMV-1) is an antigenic-variant of Newcastle disease virus (NDV) which is associated with infection in Columbidae family. In this study, we isolated two pigeon-derived strains pi/Pak/Lhr/SA_1/17 (designed as SA_1) and pi/Pak/Lhr/SA_2/17 (designed as SA_2) from diseased pigeons collected in Punjab province in 2017. We performed the whole genome, phylogenetic analysis and comparative clinico-pathological evaluation of two viruses in pigeons. Phylogenetic analysis based on fusion (F) gene and complete genome sequences showed that SA_1 belonged to sub-genotype XXI.1.1 and SA_2 clustered in sub-genotype XXI.1.2. SA_1 and SA_2 viruses contributed to morbidity and mortality in pigeons. Remarkably, although the two viruses resulted in comparatively similar pattern of pathogenesis and replication ability in various tissues of infected pigeons, SA_2 could cause more severe histopathological lesions and had comparatively high replication ability in pigeons than SA_1. Moreover, pigeons infected with SA_2 had higher shedding efficiency than that of pigeons infected with SA_1. Moreover, several aa substitutions in the major functional domains of the F and HN proteins might be contributed to the pathogenic differences between the two isolates in pigeons. Overall, these findings provide us with important insight into the epidemiology and evolution of PPMV-1 in Pakistan and laid the foundation for the further elucidation of the mechanism underlying the pathogenic difference of PPMV-1 in pigeons.

Molecular and retrospective analysis of pigeon paramyxovirus type 1 infections in confinement-reared pigeons (Columbia livia); 2010–2020

Molecular and retrospective analysis of pigeon paramyxovirus type 1 infections in confinement-reared pigeons (Columbia livia); 2010–2020

The brain-specific upregulation of CARD11 in response to avian brain-neurotropic virus infection serves as a potential biomarker

Avian neurotropic viruses are critical problems in poultry industry causing severe central nervous system (CNS) damage with neuroinvasive and neurovirulence properties. Biomarker of neurotropic viral intracranial invasion is of great application value for the diagnosis, but that of avian neurotropic viruses remains elusive. Previously, we found that chicken caspase recruitment domain family, member 11 (CARD11) was only upregulated in virulent Newcastle disease virus-infected chickens and in chicken primary neuronal cells. In this study, CARD11 was systemically expressed in chickens and pigeons detected by absolute qPCR and immunohistochemical (IHC) assay. After virus challenging, only avian neurotropic viruses (avian encephalomyelitis virus [AEV] and pigeon paramyxovirus type 1 [PPMV-1]) except Marek's disease virus (MDV) can invade brain and cause pathological changes. The relative mRNA expression of CARD11 was brain-upregulated in AEV- or PPMV-1-infected animals, rather than MDV and non-neurotropic viruses (fowl adenovirus serotype 4 [FAdV-4] and infectious bronchitis virus [IBV]). Similarly, the protein expression of CARD11 was only upregulated in the cerebra and cerebella infected by avian brain-neurotropic virus using IHC assay. And there were no correlations between the change level of CARD11 and viral load. Our preliminary data suggested that avian CARD11 may be a potential brain biomarker for avian brain-neurotropic virus invasion.

Comparative pathogenesis of two genotype VI.2 avian paramyxovirus type-1 viruses (APMV-1) in pheasants, partridges and chickens

ABSTRACT Newcastle disease (ND) is caused by virulent forms of avian paramyxovirus-1 (APMV-1) and is an economically important disease of poultry world-wide. Pigeon paramyxovirus 1 (PPMV-1), a sub-group of APMV-1 is endemic in Columbiformes and can cause infections of poultry. An outbreak of ND in partridges in Scotland, UK, in 2006 (APMV-1/partridge/UK(Scotland)/7575/06) was identified as a class II, genotype VI.2.1.1.2.1, more commonly associated with PPMV-1. It has been hypothesized that game birds may be a route of transmission into commercial poultry settings due to the semi-feral rearing system, which potentially brings them into contact with both wild-birds and poultry species. Therefore, the pathogenesis and transmission of APMV-1/partridge/UK(Scotland)/7575/06 in game birds and chickens was investigated, and compared to a contemporary PPMV-1 isolate, PPMV-1/pigeon/UK/015874/15. Viral shedding and seroconversion profiles demonstrated that pheasants were susceptible to infection with APMV-1/partridge/UK(Scotland)/7575/06 with limited clinical signs observed although they were able to excrete and transmit virus. In contrast, partridges and pheasants showed limited infection with PPMV-1/pigeon/UK/015874/15, causing mild clinical disease. Chickens, however, were productively infected and were able to transmit virus in the absence of clinical signs. From the data, it can be deduced that whilst game birds may play a role in the transmission and epidemiology of genotype VI.2 APMV-1 viruses, the asymptomatic nature of circulation within these species precludes evaluation of natural infection by clinical surveillance. It therefore remains a possibility that genotype VI.2 APMV-1 infection in game birds has the potential for asymptomatic circulation and remains a potential threat to avian production systems. RESEARCH HIGHLIGHTS Demonstration of infection of game birds with Pigeon paramyxovirus-1 (PPMV-1). There are differing dynamics of infection between different game bird species. Differing dynamics of infection between different PPMV-1 isolates and genotypes in game birds and chickens.

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.

A pigeon paramyxovirus type 1 isolated from racing pigeon as an inactivated vaccine candidate provides effective protection

Pigeon paramyxovirus type 1 (PPMV-1), a variant of Newcastle disease virus (NDV), causes severe Newcastle disease (ND) in pigeons. However, there is no PPMV-1 vaccine available worldwide. In this study, a strain of PPMV-1 was isolated from outbreaks in a vaccinated racing pigeon (Columbia livia) loft in China, namely, PPMV-1/pigeon/Gansu/China/02/2020 (GS02). Experimental infection with GS02 showed mortality rates of 100% and 87.50% in 4- and 12-week-old pigeons, respectively, suggesting that GS02 is virulent and more sensitive to young pigeons. The whole genome of GS02 determined the fusion (F) protein possessing virulence cleavage site 112RRQKRF117. Phylogenetic analysis indicated that GS02 was a subgenotype VI.2.1.1.2.2 (VIk) of Class II NDV and more closely related to the JS/06/20/Pi (MW271791) strain, but it was far from the genetic distance from the commercial vaccine chicken-origin La Sota strain. Using inactivated GS02 as a vaccine candidate and inactivated vaccine La Sota to immunize the pigeons, both of them provided complete protection against GS02 challenge. The GS02 vaccine candidate induced higher antibody titers than the La Sota vaccine, and cross-reactivity testing showed antigenically slight differences between GS02 and La Sota. These results indicated that the GS02 candidate could be a potential pigeon-derived vaccine for the prevention and control of PPMV-1 in pigeons.