COMPLETE GENOMIC SEQUENCE OF VIRULENT PIGEON PARAMYXOVIRUS IN LAUGHING DOVES (STREPTOPELIA SENEGALENSIS) IN KENYA

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.

Immunogenicity of Newcastle Disease Vaccine in Southern Ground-hornbill (Bucorvus leadbeateri)

The southern ground-hornbill (Bucorvus leadbeateri; hereafter SGH) is endangered in South Africa, Namibia, and Swaziland. Through a conservation program established in South Africa by the Mabula Ground Hornbill Project, wild populations are being re-established by the reintroduction of captive-reared birds. The SGH is susceptible to infection with avian avulavirus 1, which causes Newcastle disease (ND). Four different vaccines to protect against ND were administered through various vaccination schedules and evaluated by serologic monitoring to assess the efficiency and safety of various combinations of vaccines (live versus inactivated/killed), vaccine strains (Ulster strain, live; Avivac Cellimune, live; VG/GA strain, live; and Avivac Struvac, killed), and administration routes (intraocular versus subcutaneous versus intramuscular injection versus oral). We vaccinated 75 individuals and evaluated antibody titers in 53 individuals (24 juveniles, 13 subadults, and 16 adult SGH; 26 males and 27 females) over a period of 9 years. Antibody titers to avian avulavirus 1 in sera were monitored by a hemagglutination inhibition test. Protective titers were generated with 3/6 vaccine regimes tested in the SGH. The highest vaccine titers were established in birds vaccinated with the Ulster strain in the conjunctiva and followed with an intramuscular Struvac injection (mean log₂ titer 8.6 ± 2.6) booster. Our aim was 1) to assess whether optimal vaccination protocols could be developed and 2) to then be able, by oral administration, to remove the need to recapture free-roaming, reintroduced birds to administer the initial vaccine or booster, thus remove the threat or mortality associated with ND to this endangered avian species in both captive birds and birds released back into the wild.

Co-circulation of genotypes XIV.2 and XVIII.2 of avian paramyxovirus-1 (Newcastle disease virus) in backyard poultry in Niger

The causative agent of Newcastle disease (ND) of poultry is the avian paramyxovirus-1, also commonly known as ND virus (NDV). Like in many developing countries, ND is endemic in Niger and has significant economic impact on commercial and backyard poultry production. NDVs were characterized in Niger between 2006 and 2008 and shown to belong to genotypes XIV.1 and XVII. In order to determine the current situation regarding the virus in Niger, tracheas (n = 384) were collected for the detection of NDV from both healthy (n = 335) and sick (n = 49) backyard poultry in 2019. Of these samples, 24 from sick chickens were positive for NDV by conventional RT-PCR. Sequencing of the fusion protein gene and phylogenetic analysis revealed that the viruses belonged to either genotype XIV.2 or XVIII.2. No NDVs of genotype XIV.1 or XVII were identified in the current study highlighting the dynamic nature of NDV circulation in Niger and the region.

Detection of Newcastle Disease Virus (NDV) in Laughing Doves and the Risk of Spread to Backyard Poultry

Newcastle disease (ND) is a highly infectious viral disease of birds caused by the Newcastle disease virus (NDV) and doves have been incriminated in previous outbreaks of the disease that have discouraged backyard poultry productions. This survey was done to detect and characterize the NDV from 184 swabs from the cloacae and pharynxes of 67 trapped laughing doves and 25 backyard poultry birds. The study utilized haemagglutination assay (HA) followed by haemagglutination inhibition (HI) tests on HA positive samples to screen field samples. Conventional reverse transcriptase polymerase chain reaction (RT-PCR) was conducted on the HI positives to characterize the NDV. This study revealed that of 134 dove samples screened, 88 (65.7 %) were HA positive. Of these HA positives subjected to HI testing, 37 (42.1 %) were HI positive. Interestingly, 21 (56.8 %) of the HI positives were also RT-PCR positive: 8 lentogenic, 12 velogenic, while one had both lentogenic and velogenic NDV. Comparatively, of the 50 chicken samples screened, 23 (46 %) were HA positive; and of these, HA positives subjected to HI testing, 16 (69.6 %) were HI positive. Only 4 (25 %) of the HI positives were RTPCR positive: 3 lentogenic and a velogenic NDV. From this study it was concluded that laughing doves were demonstrated to be infected with either lentogenic or velogenic NDV or both. The use of red blood adsorption-de-adsorption concentration of NDV enhanced the RT-PCR detection using the fusion gene primers NDV-F 4829 and NDV-R 5031. The detection of not only lentogenic but velogenic NDV in laughing doves poses a great risk to backyard poultry production.

Phylogenetic Analysis of Pigeon Paramyxoviruses Type-1 Identified in Mourning Collared-doves ( Streptopelia decipiens) in Namibia, Africa

We generated the complete sequence of the fusion ( F) protein gene from six pigeon paramyxoviruses type 1 (PPMV-1) isolated from Mourning Collared-doves ( Streptopelia decipiens) in Namibia, Africa between 2016 and 2017. All of the isolates had an F gene cleavage site motif of ¹¹²RRQKRF¹¹⁷ characteristic of virulent viruses. A phylogenetic analysis using the full F gene sequence revealed that the viruses belonged to genotype VIa and were epidemiologically related to PPMV-1s from Asia, Europe, and North America.