A multi-species, multi-pathogen avian viral disease outbreak event: Investigating potential for virus transmission at the wild bird - poultry interface.

A free-range organic broiler (Gallus gallus domesticus) premises in Staffordshire was infected by high pathogenicity avian influenza virus (HPAIV) H5N8 during the 2020-2021 epizootic in the United Kingdom (UK). Following initial confirmation of the infection in poultry, multiple wild bird species were seen scavenging on chicken carcasses. Detected dead wild birds were subsequently demonstrated to have been infected and succumbed to HPAIV H5N8. Initially, scavenging species, magpie (Pica pica) and raven (Corvus corax) were found dead on the premises but over the following days, buzzards (Buteo buteo) were also found dead within the local area with positive detection of HPAIV in submitted carcasses. The subacute nature of microscopic lesions within a buzzard was consistent with the timeframe of infection. Finally, a considerable number of free-living pheasants (Phasianus colchicus) were also found dead in the surrounding area, with carcasses having higher viral antigen loads compared to infected chickens. Limited virus dissemination was observed in the carcasses of the magpie, raven, and buzzard. Further, an avirulent avian paramyxovirus type 1 (APMV-1) was detected within poultry samples as well as in the viscera of a magpie infected with HPAIV. Immunohistochemistry did not reveal colocalization of avian paramyxovirus antigens with lesions, supporting an avirulent APMV-1 infection. Overall, this case highlights scenarios in which bi-directional transmission of avian viral diseases between commercial and wild bird species may occur. It also underlines the importance of bio separation and reduced access when infection pressure from HPAIV is high.

Understanding the disease and economic impact of avirulent avian paramyxovirus type 1 (APMV-1) infection in Great Britain.

Newcastle disease (ND) is a notifiable disease affecting chickens and other avian species caused by virulent strains of Avian paramyxovirus type 1 (APMV-1). While outbreaks of ND can have devastating consequences, avirulent strains of APMV-1 generally cause subclinical infections or mild disease. However, viruses can cause different levels of disease in different species and virulence can evolve following cross-species transmission events. This report describes the detection of three cases of avirulent APMV-1 infection in Great Britain (GB). Case 1 emerged from the 'testing to exclude' scheme in chickens in Shropshire while cases 2 and 3 were made directly from notifiable avian disease investigations in chicken broilers in Herefordshire and on premises in Wiltshire containing ducks and mixed species, respectively). Class II/genotype I.1.1 APMV-1 from case 1 shared 99.94% identity to the Queensland V4 strain of APMV-1. Class II/genotype II APMV-1 was detected from case 2 while the class II/genotype I.2 virus from case 3 aligned closely with strains isolated from Anseriformes. Exclusion of ND through rapid detection of avirulent APMV-1 is important where clinical signs caused by avirulent or virulent APMV-1s could be ambiguous. Understanding the diversity of APMV-1s circulating in GB is critical to understanding disease threat from these adaptable viruses.

Research Note: Molecular surveillance of Avian Paramyxovirus type-1 in nonvaccinated village chickens in Central Rift Valley of Oromia, Ethiopia.

Newcastle disease (ND) is a major infectious disease of poultry caused by a virulent strain of Avian Paramyxovirus type-1 (APMV-1). It is a major threat to the poultry industry in many countries of the world including Ethiopia. The aim of this study was to conduct molecular surveillance of ND Virus and identify potential risk factors for nonvaccinated village chicken in Central Rift Valley of Oromia, Ethiopia. A total of 84 pooled swab samples, each made from pools of 5 swabs for analysis, from cloacal and tracheal sites of chickens in the Central Rift Valley were collected, and RNA was extracted to carry out real-time quantitative polymerase chain reaction. Out of the 84 pooled swab samples tested for M-gene, 13 (15.48%) samples were found positive for APMV-1. The prevalence of ND in males was found to be 16.10% and that in females was 14.67%. Although the overall ND prevalence was 15.48% (13/84), the highest prevalence was recorded in Adama, 42.86% (6/14), and no positive case was observed in Bote and Bishoftu (P < 0.05), while intermediate prevalence was obtained from Batu, Arsi-negele, and Shashemene (P > 0.05). In general, the present study provides important information on the epidemiology of ND based on M-gene assay in Central Rift Valley of Oromia, Ethiopia, and highlights the importance of implementing molecular surveillances practice in live poultry markets and village chickens.

Genotypic characterisation of Avian paramyxovirus type-1 viruses isolated from aquatic birds in Uganda.

Avian paramyxovirus type-1 (APMV-1) viruses of the lentogenic pathotypes are often isolated from wild aquatic birds and may mutate to high pathogenicity when they cross into poultry and cause debilitating Newcastle disease. This study characterised AMPV-1 isolated from fresh faecal droppings from wild aquatic birds roosting sites in Uganda. Fresh faecal samples from wild aquatic birds at several waterbodies in Uganda were collected and inoculated into 9-10-day-old embryonated chicken eggs. After isolation, the viruses were confirmed as APMV-1 by APMV-1-specific polymerase chain reaction (PCR). The cleavage site of the fusion protein gene for 24 representative isolates was sequenced and phylogenetically analysed and compared with representative isolates of the different APMV-1 genotypes in the GenBank database. In total, 711 samples were collected from different regions in the country from which 72 isolates were recovered, giving a prevalence of 10.1%. Sequence analysis of 24 isolates revealed that the isolates were all lentogenic, with the typical 111GGRQGR'L117 avirulent motif. Twenty-two isolates had similar amino acid sequences at the cleavage site, which were different from the LaSota vaccine strain by a silent nucleotide substitution T357C. Two isolates, NDV/waterfowl/Uganda/MU150/2011 and NDV/waterfowl/Uganda/MU186/2011, were different from the rest of the isolates in a single amino acid, with aspartate and alanine at positions 124 and 129, respectively. The results of this study revealed that Ugandan aquatic birds indeed harbour APMV-1 that clustered with class II genotype II strains and had limited genetic diversity.

Different Duck Species Infected Intramuscularly with Duck-Origin Genotype IX APMV-1 Show Discrepant Mortality and Indicate Another Fatal Genotype APMV-1 to Ducks.

Isolations of genotype IX (gIX) avian paramyxovirus type 1 (APMV-1) from various bird species have been more common recently, with isolates showing variable pathogenicity in different species of poultry. Here we sequenced the genome of a Muscovy duck origin gIX virus strain XBT14 and characterized the virulence and pathogenicity of this isolate in chickens and ducks. The genome sequence of strain XBT14 is 15,192 nt in length, containing multiple basic amino acids at the fusion protein cleavage site. The XBT14 strain shared 91.6%-91.9% nucleotide identities with early-genotype viruses (such as genotype III and IV) and shared 85.3%-85.9% nucleotide homologies with later genotype viruses (such as genotype VII). Pathogenicity tests showed that strain XBT14 could cause death in different duck breeds with a mortality rate of 44.4% in Muscovy duck, 25.9% in Sheldrake, and 11.1% in Cherry Valley duck, respectively. Similar mortality discrepancies were also observed in different ducks when infected with chicken-origin gIX virus strain F48E8. These results indicate that XBT14-like velogenic gIX APMV-1 (such as XBT14, F48E8, and GD09-2) could cause fatal infection in duck, and genotype IX is another genotype velogenic to duck as well as genotype VII. Accompanied by genetic differences in the vaccine strains or dominant strains prevailing in poultry, the virulent XBT14-like gIX viruses might become potentially endemic strains in poultry in the future.

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.

The evolution of pigeon paramyxovirus type 1 (PPMV-1) in Great Britain: a molecular epidemiological study.

Newcastle disease (ND), caused by virulent strains of avian paramyxovirus type 1 (APMV-1), is considered throughout the world as one of the most important animal diseases. For over three decades now, there has been a continuing panzootic caused by a variant virulent APMV-1 strain, so-called pigeon paramyxovirus type 1 (PPMV-1), primarily in racing pigeons, which has also spread to wild birds and poultry. PPMV-1 isolations have been made in Great Britain every year since 1983. In this study, we have completed a comparative phylogenetic analysis based on a 374 nucleotide section of the fusion protein gene of 63 isolates of PPMV-1 that were isolated over a 26-year period; 43 of these were sequenced for this study. Phylogenetic analysis of these sequences revealed that all were closely related and placed in the genetic sublineage 4b (VIb), subdivision 4biif.