Identification of Clade E Avipoxvirus, Mozambique, 2016

Snapshot of the Phylogenetic Relationships among Avian Poxviruses Circulating in Portugal between 2017 and 2023

Avipoxvirus (APV), a linear dsDNA virus belonging to the subfamily Chordopoxvirinae of the family Poxviridae, infects more than 278 species of domestic and wild birds. It is responsible for causing avian pox disease, characterized by its cutaneous and diphtheric forms. With a high transmission capacity, it can cause high economic losses and damage to the ecosystem. Several diagnostic methods are available, and bird vaccination can be an effective preventive measure. Ten APV-positive samples were analyzed to update the molecular characterization and phylogenetic analysis of viruses isolated in Portugal between 2017 and 2023. A P4b gene fragment was amplified using a PCR, and the nucleotide sequence of the amplicons was determined using Sanger sequencing. The sequences obtained were aligned using ClustalW, and a maximum likelihood phylogenetic tree was constructed. With this study, it was possible to verify that the analyzed sequences are distributed in subclades A1, A2, B1, and B3. Since some of them are quite similar to others from different countries and obtained in different years, it is possible to conclude that there have been several viral introductions in Portugal. Finally, it was possible to successfully update the data on Avipoxviruses in Portugal.

Detection and molecular characterization of Avipoxvirus in Culex spp. (Culicidae) captured in domestic areas in Rio de Janeiro, Brazil

Avian pox is a highly contagious poultry disease that causes significant economic losses. Mosquitoes belonging to the genus Culex (Diptera: Culicidae) have a fundamental role in disseminating Avipoxvirus (Poxviridae). This study proposes investigating the presence of Avipoxvirus (APV) DNA in Culex spp. from Rio de Janeiro to determine its frequency and perform a phylogenetic analysis based on the core like the 4b protein (p4b) gene. The detection of APVs was conducted individually on four hundred Culex spp. mosquitoes. A total of 12.23% (47/384) of the Culex spp. were positive in the PCR. Sequencing the p4b gene revealed that this study’s sequences displayed 98.8–99% identity with Fowlpoxvirus (FWPW) sequences available in GenBank. In the phylogenetic analysis, these APVs were clustered in the A1 subclade together with FWPW sequences from several countries. The evolutionary distance of the p4b gene was 0.61 ± 0.21% in rural areas and 0.38 ± 0.16% in peri-urban areas. The current investigation is the first study to report the detection of APVs in field-caught mosquitoes. Moreover, a high frequency of APV DNA was observed in Culex spp. captured in domestic areas, where backyard poultry is present. This data demonstrates the importance of implementing control measures for Culex spp. to mitigate the transmission of APVs in backyard poultry in Rio de Janeiro.

Outbreaks of Avipoxvirus Clade E in Vaccinated Broiler Breeders with Exacerbated Beak Injuries and Sex Differences in Severity

Avipoxvirus affects chickens and wild birds, and it is characterized by lesions on the nonfeathered parts of the body (the cutaneous form), or necrotic lesions in the upper respiratory tract (the diphtheritic form). In poultry farming, avian pox is usually controlled by live attenuated vaccines. However, there have been many reports of outbreaks, even in flocks of vaccinated birds. In the present study, different outbreaks of the emerging clade E avipoxvirus were detected in commercial breeder flocks of chickens vaccinated against fowlpox virus in Southeast Brazil. Clinical manifestations of these outbreaks included a marked prevalence of moderate to severe progressive lesions in the beaks of affected birds, especially in roosters with increased mortality (up to 8.48%). Also, a reduced hatchability (up to 20.77% fewer hatching eggs) was observed in these flocks. Analysis of clinical samples through light and transmission electron microscopy revealed the presence of Bollinger bodies and poxvirus particles in epithelial cells and affecting chondrocytes. PCR, sequencing, and phylogenetic analysis of major core protein (P4b) and DNA polymerase (pol) genes identified this virus as clade E avipoxvirus. We also developed qPCR assays for open reading frames (ORFs) 49, 114, and 159 to detect and quantify this emergent virus. These results show the arrival and initial spread of this pathogen in the poultry industry, which was associated with harmful outbreaks and exacerbated clinical manifestations in vaccinated commercial breeder flocks. This study also highlights the relevance of permanent vigilance and the need to improve sanitary and vaccination programs.

Molecular characterization of avipoxviruses circulating in Windhoek district, Namibia 2021

Samples from eleven birds (chicken, dove and peacock) with symptoms of fowlpox, caused by the avipoxvirus (APV), were collected in seven different areas of the Windhoek district, Namibia between April and October 2021. A fragment of the 4b core protein and the DNA polymerase gene of APV were amplified by PCR from the DNA of the samples and sequenced. Phylogenetic analysis revealed that the viruses present in the chickens all belonged to clade A1 while the viruses in the doves and peacock were from subclade A3.1. This is the first report of subclade A3.1 avipoxvirus in peacock. In addition, all of the samples obtained from chickens were shown by PCR to be positive for the integration of reticuloendotheliosis virus while those from the doves and peacocks were negative. This study is the first characterization of avipoxvirus in Namibia and provides additional information on the presence of avipoxvirus in southern Africa.

Identification of porcine circovirus-3 in Mozambique

Porcine circovirus 3 (PCV-3) has been associated with an assortment of clinical conditions in pigs and has been reported in many countries worldwide. In Africa there is no data on the presence of PCV-3. In this study, DNA samples collected from 91 pigs between 2011 and 2019 in nine of the ten provinces of Mozambique in the context of African swine fever (ASF) monitoring were further screened for the presence of PCV-3. Of these samples, 7 (7.5%) animals were positive for PCV-3. Sequence and phylogenetic analysis of the capsid protein gene (ORF2) of the PCV-3s provided evidence of epidemiological links with PCV-3s identified in North and South America, Asia, and Europe. This is the first identification of PCV-3 in Mozambique (and Africa) and the first evidence of co-infection of PCV-3 and ASF virus. It should provide a starting point for further investigations into the presence and impact of PCV-3 in Africa.

Atypical Manifestation of Cutaneous Fowlpox in Broiler Chickens Associated with High Condemnation at a Processing Plant

The present case is an unusual report of cutaneous fowlpox with an atypical appearance and incidence in broilers. Gross skin lesions were noticed in 41-day-old commercial broilers during the veterinary inspection at a processing plant in the north of Iran. The skin lesions were only observed on feathered skin areas of the broilers and remained unnoticed until slaughter. Round, nodular or coalescent, elongated, reddish-brown proliferative lesions were mainly located on the back, thighs, and proximal areas of the neck of broilers. Nonfeathered skin, including the wattle, comb, eyelids, and legs, were not affected. This condition incurred high losses due to a 5.3% condemnation and trimming of carcasses. Cutaneous lesions were sampled for histopathology and molecular virology for further investigations. Histopathology revealed multifocal necrotic dermatitis with epidermal eosinophilic cytoplasmic inclusion bodies in the skin lesions. Molecular investigations confirmed the presence of fowlpox virus (FWPV) in the proliferative lesions, with further investigations identifying two FWPV genome populations, one carrying a portion of the reticuloendotheliosis virus (REV) and the other a nearly complete REV provirus. Furthermore, the 4b core protein gene-based molecular analysis clustered the field virus into clade A of the genus Avipoxvirus.

Identification of Clade E Avipoxvirus in Brazil

Avian poxvirus (APV) is an enveloped double-stranded DNA virus that affects many domestic and wild birds worldwide. APVs are classified into three clades (A to C), represented by fowlpox (FP) virus (clade A), canarypox virus (clade B), and psittacinepox virus (clade C), although two additional clades (D and E) have been proposed. In this study, a tumorlike skin lesion found in a domestic fowl was submitted for molecular diagnosis of Avipoxvirus by PCR and sequencing. The phylogenetic analysis revealed that the amplified segment of the corelike 4b protein and polymerase genes clustered in clade E. The APVs in clade E were previously reported from outbreaks in Hungary (flock of turkeys) and in Mozambique (layer chickens), associated with a possible vaccine failure to protect against clade E viruses. To our knowledge, this report is the first identification of clade E in this country, providing new information about host range and genetic diversity of APVs in Brazil, and may represent a potential risk of FP disease outbreaks in commercial poultry.

Bayesian Phylogenetic Analysis of Avipoxviruses from North American Wild Birds Demonstrates New Insights into Host Specificity and Interspecies Transmission

Avian pox is commonly diagnosed in a variety of North American wild and domestic birds, yet little is known about the evolutionary relationships among the causative poxviruses. This study aimed to determine the phylogenetic relationships among isolates identified in different avian host species to better characterize the host range of specific viral strains and compare the genetic variability within and between viral clades. Skin lesions grossly and microscopically consistent with poxvirus infection from 82 birds collected in Canada, the United States, and the U.S. Virgin Islands were included in this study. A total of 12 avian species were represented; the most common species sampled were wild turkeys (Meleagris gallopavo), mourning doves (Zenaida macroura), and American crows (Corvus brachyrhynchos). Poxvirus samples from these birds were genotyped using PCR that targeted the 4b core protein gene followed by amplicon sequencing. Bayesian phylogenetic analyses of these viruses, in conjunction with publicly available sequences, representing avipoxvirus strains from six continents revealed statistically significant monophyletic clades based on genetic distances of sequences within and between observed clades. Genetic variation within the fowlpox clade was low compared to the canarypox clade. Host and geographic origins of viral isolates revealed overall clustering of viral strains within avian species, with a few exceptions. No genetic differences were observed between viruses from Canada and the United States within individual species. These results are novel in their characterization and comparison of the phylogenetic relationships of poxvirus isolates in wild bird species from North America. Further, we provide new data on the level of host specificity and specific strains circulating in North America.

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.