A molecular, epidemiological and pathogenicity analysis of pigeon paramyxovirus type 1 viruses isolated from live bird markets in China in 2014-2021.

To expand our understanding of the epidemiology of pigeon paramyxovirus type 1 (PPMV-1) in China, risk-based active surveillance was undertaken with pigeon swabs collected from live bird markets in 2014-2021. Seventy-six PPMV-1 strains were isolated from 12 provinces (60%) of the 20 provinces surveyed, and the positive rates of PPMV-1 varied from 0.50% to 3.19% annually. The complete genomic sequences of 18 representative viruses were analyzed, revealing a genome of 15,192 nucleotides, with the gene order 3'-NP-P-M-F-HN-L-5'. All isolates contained the 112RRQKRF117 cleavage site in the fusion (F) protein, a characteristic generally associated with virulent Newcastle disease viruses (NDVs), and the intracerebral pathogenicity index values (1.05-1.41) of four isolates indicated their virulence. A challenge experiment also demonstrated that all four isolates are pathogenic to pigeons, with morbidity rates of 60-100% and mortality rates of 0-30%. A further analysis of the functional domains of the F and HN proteins revealed several mutations in the fusion peptide, signal peptide, neutralizing epitopes, heptad repeat region, and transmembrane domains, and the substitution of cysteine residue 25 (C25Y) and substitutions in the HRb region (V287I) of the F protein and the transmembrane domain (V45A) of the HN protein may play important roles in PPMV-1 virulence. In a phylogenetic analysis based on the complete sequences of the F gene, all eighteen isolates all clustered into sub-genotype VI.2.1.1.2.2 (VIb) in class II, and shared high nucleotide sequence identity, indicating that the PPMV-1 strains in sub-genotype VI.2.1.1.2.2 are the predominant PPMV-1 viruses in pigeons in China and that the variations in these viruses have been relatively stable over the past 8 years. This study identifies the genetic and pathogenicity characteristics of the PPMV-1 strains prevalent in China and extends our understanding of the prevalence of this virus in China.

Traceable surveillance and genetic diversity analysis of coronaviruses in poultry from China in 2019.

Coronavirus disease 2019 (COVID-19), caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first reported in Wuhan, China, and rapidly spread throughout the world. This newly emerging pathogen is highly transmittable and can cause fatal disease. More than 35 million cases have been confirmed, with a fatality rate of about 2.9% to October 9, 2020. However, the original and intermediate hosts of SARS-CoV-2 remain unknown. Here, 3160 poultry samples collected from 14 provinces of China between September and December 2019 were tested for SARS-CoV-2 infection. All the samples were SARS-CoV-2 negative, but 593 avian coronaviruses were detected, including 485 avian infectious bronchitis viruses, 72 duck coronaviruses, and 36 pigeon coronaviruses, with positivity rates of 15.35%, 2.28%, and 1.14%, respectively. Our surveillance demonstrates the diversity of avian coronaviruses in China, with higher prevalence rates in some regions. Furthermore, the possibility that SARS-CoV-2 originated from a known avian-origin coronavirus can be preliminarily ruled out. More surveillance of and research into avian coronaviruses are required to better understand the diversity, distribution, cross-species transmission, and clinical significance of these viruses.

A Pigeon-Derived Sub-Genotype XXI.1.2 Newcastle Disease Virus from Bangladesh Induces High Mortality in Chickens.

Newcastle disease virus (NDV) is a significant pathogen of poultry; however, variants also affect other species, including pigeons. While NDV is endemic in Bangladesh, and poultry isolates have been recently characterized, information about viruses infecting pigeons is limited. Worldwide, pigeon-derived isolates are commonly of low to moderate virulence for chickens. Here, we studied a pigeon-derived NDV isolated in Bangladesh in 2010. To molecularly characterize the isolate, we sequenced its complete fusion gene and performed a comprehensive phylogenetic analysis. We further studied the biological properties of the virus by estimating mean death time (MDT) and by experimentally infecting 5-week-old naïve Sonali chickens. The studied virus clustered in sub-genotype XXI.1.2 with NDV from pigeons from Pakistan isolated during 2014-2018. Deduced amino acid sequence analysis showed a polybasic fusion protein cleavage site motif, typical for virulent NDV. The performed in vivo pathogenicity testing showed a MDT of 40.8 h, and along with previously established intracerebral pathogenicity index of 1.51, these indicated a velogenic pathotype for chickens, which is not typical for pigeon-derived viruses. The experimental infection of chickens resulted in marked neurological signs and high mortality starting at 7 days post infection (dpi). Mild congestion in the thymus and necrosis in the spleen were observed at an advanced stage of infection. Microscopically, lymphoid depletion in the thymus, spleen, and bursa of Fabricius were found at 5 dpi, which progressed to severe in the following days. Mild to moderate proliferation of glial cells was noticed in the brain starting at 2 dpi, which gradually progressed with time, leading to focal nodular aggregation. This study reports the velogenic nature for domestic chickens of a pigeon-derived NDV isolate of sub-genotype XXI.1.2. Our findings show that not all pigeon-derived viruses are of low virulence for chickens and highlight the importance of biologically evaluating the pathogenicity of NDV isolated from pigeons.

Subclinical Infection and Transmission of Clade 2.3.4.4 H5N6 Highly Pathogenic Avian Influenza Virus in Mandarin Duck (Aix galericulata) and Domestic Pigeon (Columbia livia domestica).

Since 2014, H5Nx clade 2.3.4.4 highly pathogenic avian influenza viruses (HPAIV) have caused outbreaks in wild birds and poultry in multiple continents, including Asia, Europe, Africa, and North America. Wild birds were suspected to be the sources of the local and global spreads of HPAIV. This study evaluated the infectivity, pathogenicity, and transmissibility of clade 2.3.4.4 H5N6 HPAIV in mandarin ducks (Aixgalericulata) and domestic pigeons (Columbia livia domestica). None of the birds used in this study, 20 mandarin ducks or 8 pigeons, showed clinical signs or mortality due to H5N6 HPAI infection. Two genotypes of H5N6 HPAIV showed replication and transmission by direct and indirect contact between mandarin ducks. H5N6 HPAIV replicated and transmitted by direct contact between pigeons, although the viral shedding titer and duration were relatively lower and shorter than those in mandarin ducks. Influenza virus antigen was detected in various internal organs of infected mandarin ducks and pigeons, indicating systemic infection. Therefore, our results indicate mandarin ducks and pigeons can be subclinically infected with clade 2.3.4.4 H5N6 HPAIV and transfer the virus to adjacent birds. The role of mandarin ducks and pigeons in the spread and prevalence of clade 2.3.4.4 H5N6 viruses should be carefully monitored.

A Pilot Study Investigating the Dynamics of Pigeon Circovirus Recombination in Domesticated Pigeons Housed in a Single Loft.

Pigeon circovirus (PiCV) infects pigeon populations worldwide and has been associated with immunosuppression in younger pigeons. Recombination is a common mechanism of evolution that has previously been shown in various members of the Circoviridae family, including PiCV. In this study, three groups of pigeons acquired from separate lofts were screened for PiCV, and their genome sequence was determined. Following this, they were housed in a single loft for 22 days, during which blood and cloacal swab samples were taken. From these blood and cloacal swabs, PiCV genomes were determined with the aim to study the spread and recombination dynamics of PiCV in the birds. Genome sequences of PiCV were determined from seven pigeons (seven tested PiCV positive) before they were housed together in a loft (n = 58 sequences) and thereafter from the ten pigeons from blood and cloacal swabs (n = 120). These 178 PiCV genome sequences represent seven genotypes (98% pairwise identity genotype demarcation), and they share >88% genome-wide pairwise identity. Recombination analysis revealed 13 recombination events, and a recombination hotspot spanning the 3' prime region, the replication-associated protein (rep) gene and the intergenic region. A cold spot in the capsid protein-coding region of the genome was also identified. The majority of the recombinant regions were identified in the rep coding region. This study provides insights into the evolutionary dynamics of PiCV in pigeons kept under closed rearing systems.

In Vitro and In Vivo Characterization of a Pigeon Paramyxovirus Type 1 Isolated from Domestic Pigeons in Victoria, Australia 2011.

Significant mortalities of racing pigeons occurred in Australia in late 2011 associated with a pigeon paramyxovirus serotype 1 (PPMV-1) infection. The causative agent, designated APMV-1/pigeon/Australia/3/2011 (P/Aus/3/11), was isolated from diagnostic specimens in specific pathogen free (SPF) embryonated eggs and was identified by a Newcastle Disease virus (NDV)-specific RT-PCR and haemagglutination inhibition (HI) test using reference polyclonal antiserum specific for NDV. The P/Aus/3/11 strain was further classified as PPMV-1 using the HI test and monoclonal antibody 617/161 by HI and phylogenetic analysis of the fusion gene sequence. The isolate P/Aus/3/11 had a slow haemagglutin-elution rate and was inactivated within 45 min at 56 °C. Cross HI tests generated an R value of 0.25, indicating a significant antigenic difference between P/Aus/3/11 and NDV V4 isolates. The mean death time (MDT) of SPF eggs infected with the P/Aus/3/11 isolate was 89.2 hr, characteristic of a mesogenic pathotype, consistent with other PPMV-1 strains. The plaque size of the P/Aus/3/11 isolate on chicken embryo fibroblast (CEF) cells was smaller than those of mesogenic and velogenic NDV reference strains, indicating a lower virulence phenotype in vitro and challenge of six-week-old SPF chickens did not induce clinical signs. However, sequence analysis of the fusion protein cleavage site demonstrated an 112RRQKRF117 motif, which is typical of a velogenic NDV pathotype. Phylogenetic analysis indicated that the P/Aus/3/11 isolate belongs to a distinct subgenotype within class II genotype VI of avian paramyxovirus type 1. This is the first time this genotype has been detected in Australia causing disease in domestic pigeons and is the first time since 2002 that an NDV with potential for virulence has been detected in Australia.

Pigeon adenovirus and pigeon torque teno virus associated with acute multifocal hepatic necrosis in pigeons in Queensland, Australia.

In 2018, an outbreak resulting in deaths of 28 breeding pigeons was reported north of Brisbane, Australia. The affected birds had runny nasal discharge and poor body condition. Two birds were submitted to Biosecurity Sciences Laboratory, Brisbane, for investigation. A range of diagnostic tests excluded a number of known pathogens, and no virus was isolated in cell culture. Histopathological examination revealed severe acute multifocal necrosis in the liver with eosinophilic intranuclear inclusions in hepatocytes and Kupffer cells. High-throughput sequencing (HTS) revealed full-length sequences for pigeon adenovirus 1 (PiAd-A) and pigeon torque teno virus (PTTV). This report indicates concomitant PiAd-1and PTTV infections in Australian pigeons.

Prevalence of pigeon rotavirus infections: animal exhibitions as a risk factor for pigeon flocks.

A total of 289 cloacal swabs from pigeons from 29 different breeders in Germany were collected. In addition, samples from pigeons exhibited at shows were collected. The detailed health status of the pigeon flocks was recorded. Samples were analysed for the presence of the recently discovered pigeon rotavirus and pigeon circovirus. Pigeon rotavirus was found in 10.3% and pigeon circoviruses was found in 65.5% of sampled pigeon lofts. The study revealed a strong relationship between the attendance of shows and the occurrence of different clinical signs. The higher prevalence of pigeon rotavirus in exhibited animals indicates that exhibitions are a risk factor for the transmission of this pathogen.

Probiotic supplementation containing Bacillus velezensis enhances expression of immune regulatory genes against pigeon circovirus in pigeons (Columba livia).

AIMS: In this study, we aimed to isolate and evaluate the efficacy of Bacillus velezensis as a probiotic and to assess its activity towards pigeons infected with pigeon circovirus (PiCV). METHODS AND RESULTS: Bacillus velezensis, isolated from pigeon faeces, was orally administered to pigeons for 60 days. After pigeons were challenged with PiCV, the PiCV viral load and expression of indicator genes for innate immunity were detected in spleen tissue and faeces of pigeons. Bacillus velezensis significantly reduced the PiCV viral load in the faeces and spleen of pigeons 5 days post-challenge (dpc). The mRNA expression levels of treated pigeons showed that interferon-gamma (IFN-γ), myxovirus resistance 1 (Mx1), and signal transducers and activators of transcription 1 (STAT1) genes were upregulated, whereas no expression of interleukin-4 (IL-4) was detected. Moreover, toll-like receptor 2 (TLR2) and 4 (TLR4) were significantly upregulated in probiotic-treated pigeons (P < 0·05). CONCLUSIONS: This is the first report showing that probiotic supplementation can effectively enhance the T-helper type 1 immune response and decrease the PiCV viral loads in pigeons. SIGNIFICANCE AND IMPACT OF THE STUDY: This study proposes that the administration of a probiotic strain, B. velezensis, to pigeons can protect against PiCV infection.

Infectivity and pathobiology of H7N1 and H5N8 high pathogenicity avian influenza viruses for pigeons (Columba livia var. domestica).

Avian influenza (AI) is one of the most important viral diseases in poultry, wildlife and humans. Available data indicate that pigeons play a minimum role in the epidemiology of AI. However, a degree of variation exists in the susceptibility of pigeons to highly pathogenic AI viruses (HPAIVs), especially since the emergence of the goose/Guangdong H5 lineage. Here, the pathogenesis of H5N8 HPAIV in comparison with a H7N1 HPAIV and the role of pigeons in the epidemiology of these viruses were evaluated. Local and urban pigeons (Columba livia var. domestica) were intranasally inoculated with 105 ELD50 of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored during 14 days. Several pigeons inoculated with H5N8 or H7N1 seroconverted. However, clinical signs, mortality, microscopic lesions and viral antigen were only detected in a local pigeon inoculated with H5N8 HPAIV. This pigeon presented prostration and neurological signs that correlated with the presence of large areas of necrosis and widespread AIV antigen in the central nervous system, indicating that the fatal outcome was associated with neurological dysfunction. Viral RNA in swabs was detected in some pigeons inoculated with H7N1 and H5N8, but it was inconsistent, short-term and at low titres. The present study demonstrates that the majority of pigeons were resistant to H5N8 and H7N1 HPAIVs, despite several pigeons developing asymptomatic infections. The limited viral shedding indicates a minimum role of pigeons as amplifiers of HPAIVs, regardless of the viral lineage, and suggests that this species may represent a low risk for environmental contamination. RESEARCH HIGHLIGHTS H7N1 and H5N8 HPAIVs can produce subclinical infections in pigeons. The mortality caused by H5N8 HPAIV in one pigeon was associated with neurological dysfunction. Pigeons represent a low risk for environmental contamination by HPAIVs.

Novel Gyrovirus genomes recovered from free-living pigeons in Southern Brazil.

Wild birds carry a number of infectious agents, some of which may have pathogenic potential for the host and others species, including humans. Domestic pigeons (Columba livia) are important targets of study since these increasingly cohabit urban spaces, being possible spillover sources of pathogens to humans. In the present study, two genomes (PiGyV_Tq/RS/Br and PiGyV_RG/RS/Br), representative of Gyrovirus genus, family Anelloviridae, were detected in sera of free-living pigeons collected in Southern Brazil. The genomes exhibit less than 50% identity to previously described members of Gyrovirus genus, suggesting that they constitute a new viral species circulating in pigeons, to which the name "pigeon gyrovirus (PiGyV)" is proposed. The current study characterizes these two PiGyV genomes which, to date, are the first gyrovirus species identified in domestic pigeons.

Pathogenicity and transmissibility of clade 2.3.4.4 highly pathogenic avian influenza virus subtype H5N6 in pigeons.

Pigeons were previously thought to be resistant to H5 viruses and to play a minimal role in spreading these viruses. In this study, we evaluated the pathogenicity of two clade 2.3.4.4 H5N6 viruses in pigeons and the potential viral transmissibility to specific-pathogen-free chickens in direct close contact with experimentally infected pigeons. No pigeons from the A/goose/Eastern China/Xin/2015 (GS/Xin) group exhibited clinical signs or mortality, and the virus was only detected in a few organs. However, 3 of 12 pigeons inoculated with the A/goose/Eastern China/0326/2015 (GS/0326) virus died, and 7 of 12 showed neurological symptoms and efficient viral replication in multiple organs. In both groups, viral shedding occurred in only some of the pigeons, the shedding period was relatively short, and the infection was not transmitted to the chickens. We also used chicken, duck, and BALB/c mouse models to evaluate the pathogenicity of the two H5N6 isolates. Both H5N6 isolates showed highly pathogenic to chickens but different degrees of pathogenicity in mice. Interestingly, in ducks, the intravenous pathogenicity index indicated that the GS/Xin isolate was low pathogenic, and the GS/0326 isolate was highly pathogenic, corresponding to the pathogenicity in pigeons. Our results indicated that the pathogenicity of the clade 2.3.4.4 H5N6 virus is diverse in pigeons, and pigeons contribute little to its transmission among poultry. However, pigeons may still be potential healthy reservoirs of the H5N6 highly pathogenic avian influenza virus.

Common bacterial, viral, and parasitic diseases in pigeons (Columba livia): A review of diagnostic and treatment strategies.

Pigeons (Columba livia) have been associated with humans for a long time now. They are raised for sport (pigeon race), exhibition (display of fancy breeds), food, and research. Most of the pigeons kept are Racing Homers, trained to compete in the pigeon race. Other breeds, such as Rollers, Nose Divers, Doneks are bred for their aerial abilities. Incorporation of a good preventive medicine program is one of the most critical factors in averting infectious diseases in pigeon flocks. This review summarizes the common bacterial, viral, and parasitic infections in pigeons. The different clinical signs, symptoms, diagnostic strategies, prevention, and treatments were described in this review. Current researches, molecular diagnostic assays, and treatment strategies such as vaccines and drug candidates were included. The information found in this review can provide insights for veterinarians and researchers studying pigeons to develop effective and efficient immunoprophylactic and diagnostic tools for pigeon diagnosis and therapeutics.

Molecular characterization and pathogenesis of H9N2 avian influenza virus isolated from a racing pigeon.

H9N2 avian influenza viruses (AIVs) can cross species barriers and expand from birds tomammals and humans. It usually leads to economic loss for breeding farms and poses a serious threat to human health.This study investigated the molecular characteristics of H9N2 AIV isolated from a racing pigeon and its pathogenesis in BALB/c mice and pigeons. Phylogenetic analysis indicated that the H9N2 virus belonged to the Ck/BJ/94-like lineage, and acquired multiple specific amino acid substitutions that might contribute to viral transmission from birds to mammals and humans. A pathogenesis study showed that both mice and pigeons infected with H9N2 virus showed clinical signs and mortality. The H9N2 viruses efficiently replicated in mice and pigeons. In our study, high levels of viral shedding were detected in pigeons, but the infection was not transmitted to co-housed pigeons. Histopathological examination revealed the presence of inflammatory responses in the infected mice and pigeons. Immunohistochemical analysis showed the presence of H9N2 virus in multiple organs of the infected mice and pigeons. Moreover, the infected mice and pigeons demonstrated significant cytokine/chemokine production. Our results showed that the H9N2 virus can infect mice and pigeons, and can not be transmitted between pigeons through direct contact.

Comparative pathogenicity of two closely related Newcastle disease virus isolates from chicken and pigeon respectively.

Newcastle disease (ND), caused by virulent Newcastle disease virus (NDV), is a highly contagious disease that has led to tremendous economic losses worldwide. Pigeon paramyxovirus type 1 (PPMV-1) is an antigenic and host variant of NDV. However, limited in-depth studies are available concerning side-by-side comparison of pathogenicity of PPMV-1 and its phylogenetically close NDV both in chickens and pigeons. To this end, two phylogenetically closely related NDV isolates, Kuwait 256 and JS/07/04/Pi from chicken and pigeon respectively were pathotypically and genotypically characterized in this study. The results indicated that Kuwait 256 was a velogenic strain, while JS/07/04/Pi was a mesogenic strain based on the mean death time of chick embryos (MDT) and intracerebral pathogenicity index in 1-day-old chicks (ICPI). Pathogenicity tests showed that Kuwait 256 caused severe clinical signs and 100 % mortality, while JS/07/04/Pi caused no apparent disease in chickens. Interestingly, both Kuwait 256 and JS/07/04/Pi caused morbidity and mortality in pigeons. Notably, pigeons infected with JS/07/04/Pi exhibited viral shedding for longer time compared to Kuwait 256-infected pigeons. Collectively, the findings of this study suggested that PPMV-1 decreased the pathogenicity in chickens but gained a survival advantage over NDV of chicken origin after its adaptive variation in pigeons based on the previous evidence that PPMV-1 originated from chicken-origin viruses. This study laid the foundation for the elucidation of the molecularmechanism underlying difference in pathogenicity of PPMV-1 and chicken-origin NDV in chickens.

Characterization of ten paramyxovirus type 1 viruses isolated from pigeons in China during 1996-2019.

Pigeon paramyxovirus type 1 (PPMV-1) is an antigenic variant of avian paramyxovirus type 1, which mainly infects pigeons. Here, we characterized ten PPMV-1 viruses isolated from pigeons in China during 1996-2019. Phylogenetic analysis of available complete genomes, F and HN genes of PPMV-1 from China showed that multiple PPMV-1 genotypes (I, II, VI, and VII) exist in pigeons in China. Ten PPMV-1 viruses isolated in this study belonged to genotypes VI.1.2.2.2, VI.2.1.1.2.1, VI.2.1.1.2.2 and VII respectively. Genotype VI is predominant in pigeons. VI.2.1.1.2.2 contains most recently isolated PPMV-1 viruses, suggesting that VI.2.1.1.2.2 is a prevalent genotype in pigeons in China. In vitro and in vivo studies showed that four representative viruses from genotypes VI.2.1.1.2.1 (TA14), VI.2.1.1.2.2 (SD19), VI.1.2.2.2 (SD16), and VII (JN08) could replicate efficiently in chicken embryo fibroblasts, while the replication titer of JN08 (VII) virus was significantly lower than that of VI gene viruses in pigeon embryo fibroblasts. The TA14 (VI.2.1.1.2.1) and SD19 (VI.2.1.1.2.2) viruses caused 20 % and 30 % mortality in pigeons, respectively. No birds infected with SD16 (VI.1.2.2.2) died during the study period. JN08 (VII) virus did not cause obvious clinical signs in infected pigeons. All data indicated that VI.2.1.1.2.2 is the prevalent genotype circulating in China and poses a major threat to pigeons, suggesting that a matched vaccine is necessary to control the disease.

Complete Genome Sequencing, Molecular Epidemiological, and Pathogenicity Analysis of Pigeon Paramyxoviruses Type 1 Isolated in Guangxi, China during 2012-2018.

Newcastle disease is an important poultry disease that also affects Columbiform birds. The viruses adapted to pigeons and doves are referred to as pigeon paramyxoviruses 1 (PPMV-1). PPMV-1 are frequently isolated from pigeons worldwide and have the potential to cause disease in chickens. The complete genomes of 18 PPMV-1 isolated in China during 2012-2018 were sequenced by next-generation sequencing (NGS). Comprehensive phylogenetic analyses showed that five of the viruses belong to sub-genotype VI1.2.1.1.2.1 and 13 isolates belong to sub-genotype VI.2.1.1.2.2. The results demonstrate that these sub-genotypes have been predominant in China during the last decade. The viruses of these sub-genotypes have been independently maintained and continuously evolved for over 20 years, and differ significantly from those causing outbreaks worldwide during the 1980s to 2010s. The viral reservoir remains unknown and possibilities of the viruses being maintained in both pigeon farms and wild bird populations are viable. In vivo characterization of the isolates' pathogenicity estimated mean death times between 62 and 114 hours and intracerebral pathogenicity indices between 0.00 and 0.63. Cross-reactivity testing showed minor antigenic differences between the studied viruses and the genotype II LaSota vaccine. These data will facilitate PPMV-1 epidemiology studies, vaccine development, and control of Newcastle disease in pigeons and poultry.

Influence of pigeon interferon alpha (PiIFN-α) on pigeon circovirus (PiCV) replication and cytokine expression in Columba livia.

Pigeon circovirus (PiCV) is the most diagnosed virus in pigeons (Columba livia) and have been studied and reported globally. PiCV infections can lead to immunosuppression and pigeons infected with PiCV can result to lymphocyte apoptosis and atrophy of immune organs. Young pigeon disease syndrome (YPDS) is a complex disease and believed that PiCV could be one of the agents leading to this syndrome. An effective treatment regimen is needed to control the spread of PiCV in pigeons. In this study pigeon interferon alpha (PiIFN-α) was cloned and expressed and its antiviral effects were tested against fowl adenovirus type 4 (FAdV-4) in vitro and PiCV in vivo. No detectable levels of FAdV-4 viral genome in LMH cells stimulated with 300 µg/mL PiIFN-α were found. Additionally, PiIFN-α was stable at different temperature and pH for 4 h, and no reduction in antiviral activity was observed in untreated and treated cells. In pigeons naturally and experimentally infected by PiCV, no detectable levels of PiCV virus titers were found after treatment with PiIFN-α. Cytokine and ISG expression levels in liver and spleen samples were detected and IFN-γ and Mx1 genes were dominantly up-regulated following PiIFN-α treatment (p < 0.05). This study demonstrated that PiCV can be inhibited by administration of PiIFN-α and PiFN-α can be used as a therapeutic approach to prevent the spread of PiCV in pigeons.

Experimental pigeon paramyxovirus-1 infection in chicken: evaluation of infectivity, clinical and pathological manifestations and diagnostic methods.

Several pigeon paramyxovirus-1 (PPMV-1) outbreaks in feral pigeons were described recently in Switzerland. The potential of PPMV-1 to induce the notifiable Newcastle disease in chickens is discussed controversially. Therefore, in order to study epidemiologically relevant parameters such as the kinetics of PPMV-1 replication and shedding as well as seroconversion after infection, chickens were infected experimentally with a Swiss PPMV-1 isolate. This generated also defined sample material for the comparison of diagnostic tests. The infectivity of the Swiss PPMV-1 isolate for chickens was demonstrated successfully by virus shedding after experimental inoculation. Our data suggest that long-lasting shedding for up to 60 days can occur in chickens infected with PPMV-1. The isolate used here was of low pathogenicity for chickens. Different quantitative reverse transcription PCR assays were evaluated with a set of Swiss PPMV-1 isolates, and various samples from experimentally infected chickens were analysed with respect to their suitability for viral RNA detection. At 14 days post-infection, virus genome was detected mainly in spleen, caecal tonsils, heart, cloacal swabs, liver, proventriculus, duodenum and kidney tissue samples. Overall, the level of virus replication was low. Not all assays used routinely in diagnostics were capable of detecting viral genome from the isolates tested. Possible explanations are the genetic divergence of PPMV-1 and the low level of viral RNA in the samples. In contrast, two methods that are not used routinely proved more suitable for virus-genome detection. Importantly, the collection of material from various different organs is recommended, in addition to the kidney and brain analysed routinely. In conclusion, this study shows that there is a need to reconsider the type of samples and the protocols used for the detection of PPMV-1 RNA in chickens.

The emergence of subclades A1 and A3 avipoxviruses in India.

During the years 2010-2018, avipoxvirus (APV) outbreaks were observed in the domestic chickens and pigeons present in the eastern Indian state of Odisha. Based on typical pox lesions, followed by molecular techniques, the overall morbidity was found to be 18%-19.23% and 16.92%-23% in chickens and pigeons, respectively. The cutaneous forms of the disease were observed with varied rates of mortality, being 47.36%-52.77% in chickens and 39.13%-92% in pigeons. PCR amplification targeting the viral P4b core protein-coding gene and the DNA polymerase gene confirmed the presence of APV strains in 10 birds. Subsequent phylogenetic analysis of these two genes confirmed that the circulating strains were members of APV clade A. The subclade analysis revealed the introduction of A1 and A3 subclades in Indian chickens and pigeons, respectively. This study is the first molecular record of APVs circulating in eastern Indian birds (Odisha) and involves the first use of the polymerase gene to reveal the circulating clades of Indian APVs.