Fatal Human Neurologic Infection Caused by Pigeon Avian Paramyxovirus-1, Australia

Avian paramyxovirus type 1 (APMV-1) is a virus of birds that results in a range of outcomes, from asymptomatic infections to outbreaks of systemic respiratory and neurologic disease, depending on the virus strain and the avian species affected. Humans are rarely affected; those who are predominantly experience mild conjunctivitis. We report a fatal case of neurologic disease in a 2-year-old immunocompromised child in Australia. Metagenomic sequencing and histopathology identified the causative agent as the pigeon variant of APMV-1. This diagnosis should be considered in neurologic conditions of undefined etiologies. Agnostic metagenomic sequencing methods are useful in such settings to direct diagnostic and therapeutic efforts.

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.

Concurrent pigeon paramyxovirus-1 and Acinetobacter baumannii infection in a fatal case of pneumonia

Pigeon paramyxovirus type 1 (PPMV-1), an antigenic variant of avian paramyxovirus type 1 (APMV-1), mainly infects pigeons. PPMV-1 genotype VI is the dominant genotype infecting pigeons in China. Human infection of avian paramyxovirus was rarely reported, and usually developed mild symptoms, such as conjunctivitis. We detected PPMV-1 in the lower respiratory sample from a fatal case with severe pneumonia; this patient aged 64 years presented cough, fever, and haemoptysis for 8 days and was admitted to hospital on Dec 26, 2020. He developed acute respiratory distress syndrome and sepsis in the following days and died of multiple organ failure on Jan 7, 2021. Sputum and blood culture reported multidrug-resistant Acinetobacter baumannii (ABA) for samples collected on days 22 and 19 post-illness, respectively. However, clinical metagenomic sequencing further reported PPMV-1 besides ABA in the bronchoalveolar lavage fluid. The PPMV-1 genome showed 99.21% identity with a Chinese strain and belonged to VI genotype by BLAST analysis. Multiple basic amino acids were observed at the cleavage site of F protein (113RKKRF117), which indicated high virulence of this PPMV-1 strain to poultry. The patient had close contact with pigeons before his illness, and PPMV-1 nucleic acid was detected from the pigeon feather. PPMV antibody was also detected in the patient serum 20 days after illness. In conclusion, concurrent PPMV-1 genotype VI.2.1.1.2.2 and ABA infection were identified in a fatal pneumonia case, and cross-species transmission of PPMV-1 may occur between infected pigeons and the human being.

Biological Characterization and Evolutionary Dynamics of Pigeon Paramyxovirus Type 1 in China

Pigeon paramyxovirus type 1 (PPMV-1) is considered as an antigenic variant of Newcastle disease virus (NDV) which has an obvious host preference for pigeons and has caused significant economic losses to the global poultry industry. The evolutionary dynamics of PPMV-1 in China, however, are poorly understood. In this study, we characterized seven PPMV-1 isolates from diseased pigeons collected in Jiangsu, Anhui, and Henan provinces during 2020. Phylogenetic analysis revealed that seven isolates belonged to sub-genotype VI.2.1.1.2.2. Biological characterization indicated that seven isolates were mesogenic based on the mean death time (69.6-91.2 h) and intracerebral pathogenicity index (1.19-1.40) and had similar growth kinetics in chicken embryos and CEFs. Furthermore, the four representative viruses (AH/01/20/Pi, JS/06/20/Pi, HN/01/20/Pi, and HN/02/20/Pi) could result in marked cytopathic effects (CPE) in CEFs and induced syncytium formation in Vero cells. Our Bayesian phylogenetic analysis showed that PPMV-1 might first emerge in East China in 1974 and East China had the highest genotypic diversity of PPMV-1. Besides, phylogeographic analysis indicated that East China and South China were probably the major epicenters of dissemination of PPMV-1 in China. Selection pressure analysis and amino acid substitutions analysis revealed that the viral replication complex (NP, P, and L proteins) was likely related with the host preference of PPMV-1. Collectively, this study uncovered the epidemiology and evolutionary dynamics of PPMV-1 circulating in China, emphasizing the importance of strengthening the monitoring of PPMV-1 in East China and South China and providing significant clues for further studies on the molecular mechanism underlying host preference of PPMV-1.

Phylogenetic analysis and pathogenicity assessment of pigeon paramyxovirus type 1 circulating in China during 2007-2019

Pigeon paramyxovirus type 1 (PPMV-1) is an antigenic variant of Newcastle disease virus (NDV) which is mainly associated with infections of pigeons and has the potential to result in disease in chickens. In this study, we characterised 21 PPMV-1 isolates from diseased pigeons in China during 2007-2019. Phylogenetic analysis revealed that all isolates belonged to genotype VI. Among them, most isolates belonged to sub-genotype VI.2.1.1.2.2, suggesting that VI.2.1.1.2.2 has become a prevalent genotype in pigeons in China. The results showed that all PPMV-1 isolates were mesogenic in nature according to the mean death time (MDT) and intracerebral pathogenicity index (ICPI). In vitro and in vivo studies demonstrated that two genetically closely related isolates (Pi-11 and Pi-10) both of which belonged to sub-genotype VI.2.1.1.2.2 had similar replication kinetics in cells derived from pigeons, while the replication titre of Pi-11 was significantly higher than that of Pi-10 in cells derived from chickens. Pi-11 and Pi-10 could contribute to morbidity and mortality in pigeons. Remarkably, although the two viruses resulted in no apparent disease symptom in chickens, Pi-11 could cause more severe histopathological lesions and had a stronger replication ability in chickens compared to Pi-10. Moreover, chickens infected with Pi-11 had higher shedding efficiency than chickens infected with Pi-10. Additionally, several mutations within important functional regions of the fusion (F) and haemagglutinin-neuraminidase (HN) proteins might be associated with different pathogenicity of the two viruses in chickens. Collectively, these results indicated that the Pi-11-like virus of pigeon origin has the potential to induce severe outbreaks in chicken flocks. These findings will help us better understand the epidemiology and evolution of PPMV-1 in China and serve as a foundation for the further investigation of the mechanism underlying the pathogenic difference of PPMV-1 isolates in chickens.

Innate immune responses of domestic pigeons to the infection of pigeon paramyxovirus type 1 virus

Pigeon paramyxovirus type 1 (PPMV-1) is a globally distributed, virulent member of the avian paramyxovirus type-1. The PPMV-1-associated disease poses a great threat to the pigeon industry. The innate immune response is crucial for antiviral infections and revealing the pathogenic mechanisms of PPMV-1. In this study, we evaluated the pathogenicity of a PPMV-1 strain LHLJ/110822 in one-month-old domestic pigeons, as well as the host immune responses in PPMV-1-infected pigeons. We observed typically clinical sign in infected pigeons by 3 dpi. The morbidity rate and the mortality in pigeons inoculated with the PPMV-1 strain were up to 100% and 30%, respectively. The virus could replicate in all of the examined tissues, namely trachea, lung, liver, spleen, and bursa of Fabricius. In addition, the infected pigeons had developed anti-PPMV-1 antibodies as early as 8 dpi; and the antibody level increased over the time in this study. The expression level of toll-like receptor (TLR) 2, TLR3 TLR15, IFN-γ, and IL-6 were significantly upregulated by the PPMV-1 infection in some tissues of pigeons. By contrast, PPMV-1 infection results in downregulation of IL-18 expression in most of investigated tissues except for bursa of Fabricius in this study. The current results confirmed that this virus could replicate in pigeons and induce host immune responses, then leading to produce serum antibody titers. Meanwhile, the PPMV-1 infection induces strong innate immune responses and intense inflammatory responses at early stage in pigeon which may associate with the viral pathogenesis.

The Ntail region of nucleocapsid protein is associated with the pathogenicity of pigeon paramyxovirus type 1 in chickens

The nucleoprotein (NP) of pigeon paramyxovirus type 1 (PPMV-1) and other paramyxoviruses plays an important role in virus proliferation. A previous study found that NP is associated with the low pathogenicity of PPMV-1 strains in chickens. Here, we investigated which domain of NP is responsible for regulating the pathogenicity of PPMV-1. We found that the Ntail sequences were more diverse for different viral genotypes compared to Ncore sequences. The chimeric rBJ-SG10Ntail strain caused more severe clinical symptoms than the parental rBJ strain, increased the viral copy number in sampled tissues and induced higher IFN-γ gene expression. This demonstrated that the Ntail sequence plays a role in regulating viral virulence. These findings increase our understanding of the Ntail of NP protein and the virulence factors associated with PPMV-1.

Characterization and Epidemiology of Pigeon Paramyxovirus Type-1 Viruses (PPMV-1) Isolated in Macedonia

We have characterized in this study 10 PPMV-1 isolated from domestic pigeons and one PPMV-1 isolated from a feral pigeon in the period 2007-2012, using both classical methods (HI test and ICPI test) and molecular methods (RT-qPCR, RT-PCR, and nucleotide sequencing). Using phylogenetic analysis of partial fusion gene sequences, these viruses clustered with recent European PPMV-1 isolates (EU/re) within the genotype VIb/1. All isolates possessed virulent cleavage site motifs with variable morbidity and mortality in pigeons. The intracerebral pathogenecity indices of the five isolates ranged from 0.59 to 1.53. The repetitive isolation of PPMV-1 viruses for several consecutive years led toward establishing enzootic presence of the disease in pigeons. A high nucleotide sequence homology between the Macedonian isolates and EU/re isolates was shown. Co-circulation of different isolates in the same holdings was detected. This is the first study to extensively describe the molecular epidemiology of PPMV-1 isolated in Macedonia.

Six-year surveillance of Newcastle disease virus in wild birds in north-eastern Spain (Catalonia)

Given that Newcastle disease (ND) is one of the major threats for the poultry industry, testing of Newcastle disease virus (NDV) has been carried out since 2010 in cases of mortality in wild birds (passive surveillance) in Catalonia. The objective is to provide an early warning system to prevent the infection of poultry. Since 2010, 35 episodes of mortality in wild birds were attributed to NDV infection. Throughout this period there was a progressive expansion of NDV to new areas, with an increase in the episodes of mortality, although it is not clear whether they were the result of the spread of the virus, or of the improvement of the surveillance. Phylogenetic analyses indicate that two distinct sublineages of NDV, 4a and 4b, were circulating in Catalonia. Both sublineages seem to be endemic in the wild bird population, affecting mainly Eurasian-collared doves, with a clear pattern in relation to its spatial distribution (coincident with the distribution of this species), and its temporal distribution (with the majority of cases between September and February). So far, endemicity in wild birds has not resulted in ND outbreaks in poultry. However, there are still many uncertainties about, for example, whether NDV may expand to new areas of Catalonia (with higher poultry density), or about the threat that the apparently more novel sublineage 4a may represent. Hence, efforts should be made so that measures to prevent infection of poultry farms (particularly in high-risk areas and periods) are encouraged, and surveillance is maintained.