Molecular Characterization of Velogenic Newcastle Disease Virus (Sub-Genotype VII.1.1) from Wild Birds, with Assessment of Its Pathogenicity in Susceptible Chickens

Abstract

Newcastle disease (ND) is considered to be one of the most economically significant avian viral diseases. It has a worldwide distribution and a continuous diversity of genotypes. Despite its limited zoonotic potential, Newcastle disease virus (NDV) outbreaks in Egypt occur frequently and result in serious economic losses in the poultry industry. In this study, we investigated and characterized NDV in wild cattle egrets and house sparrows. Fifty cattle egrets and fifty house sparrows were collected from the vicinity of chicken farms in Kafrelsheikh Governorate, Egypt, which has a history of NDV infection. Lung, spleen, and brain tissue samples were pooled from each bird and screened for NDV by real-time reverse transcriptase polymerase chain reaction (RRT-PCR) and reverse transcriptase polymerase chain reaction (RT-PCR) to amplify the 370 bp NDV F gene fragment. NDV was detected by RRT-PCR in 22 of 50 (44%) cattle egrets and 13 of 50 (26%) house sparrows, while the conventional RT-PCR detected NDV in 18 of 50 (36%) cattle egrets and 10 of 50 (20%) of house sparrows. Phylogenic analysis revealed that the NDV strains identified in the present study are closely related to other Egyptian class II, sub-genotype VII.1.1 NDV strains from GenBank, having 99.7%–98.5% identity. The pathogenicity of the wild-bird-origin NDV sub-genotype VII.1.1 NDV strains were assessed by experimental inoculation of identified strains (KFS-Motobas-2, KFS-Elhamoul-1, and KFS-Elhamoul-3) in 28-day-old specific-pathogen-free (SPF) Cobb chickens. The clinical signs and post-mortem changes of velogenic NDV genotype VII (GVII) were observed in inoculated chickens 3 to 7 days post-inoculation, with 67.5%–70% mortality rates. NDV was detected in all NDV-inoculated chickens by RRT-PCR and RT-PCR at 3, 7, and 10 days post-inoculation. The histopathological findings of the experimentally infected chickens showed marked pulmonary congestion and pneumonia associated with complete bronchial stenosis. The spleen showed histocytic cell proliferation with marked lymphoid depletion, while the brain had malacia and diffuse gliosis. These findings provide interesting data about the characterization of NDV in wild birds from Egypt and add to our understanding of their possible role in the transmission dynamics of the disease in Egypt. Further research is needed to explore the role of other species of wild birds in the epidemiology of this disease and to compare the strains circulating in wild birds with those found in poultry.

Newcastle Disease Genotype VII Outbreaks in Poultry across Egypt are associated with Enzootic Prevalence of the Virus in Wild Birds

“…These clinical and postmortem observations correlate to disease manifestation findings of birds infected with VNDV in other studies [10,[65][66][67]. However, all examined migratory and non-migratory wild birds that were positive for NDV had no apparent clinical disease signs or post-mortem lesions, which are coherent with the findings recorded in previous studies related to ND infections in wild birds [30,58].…”

“…Conversely, low detection rate of NDV was recorded in wild birds with percentage of 5.18% [50]; 3.06% [47], and 3.77% [29]. In view of a few studies carried out in Egypt on wild bird species, velogenic NDV sub-genotype VII.1.1 was isolated from cattle egret and house sparrows that were collected from the vicinity of poultry farms with a history of NDV infection [30]. Among the 85 samples positive for NDV, the majority 71 (61.6%) contained NDV alone but 14 samples (38.4%) contained both NDV and AIV.…”

Pathogenesis of Velogenic Genotype VII.1.1 Newcastle Disease Virus Isolated from Chicken in Egypt via Different Inoculation Routes: Molecular, Histopathological, and Immunohistochemical Study

“…Newcastle disease (ND) is a highly contagious viral disease which infects a wide variety of domestic and wild bird species [ 1 , 2 , 3 ]. The disease produces drastic economic losses worldwide.…”

“…Velogenic NDV strains can be further subdivided into viscerotropic, which cause severe intestinal and visceral hemorrhages, and neurotropic, which cause severe neurologic clinical signs and encephalitis [ 2 , 16 , 17 , 18 ]. Among poultry, ND has a wide prevalence of infection in over 200 kinds of birds [ 2 , 3 , 19 ]. In many countries, novel genotype VII displayed marked virulence and wide tissue tropism.…”

Monitoring of aquatic birds and surveillance of avian influenza and Newcastle disease of waterfowls at the National Park of Urmia Lake

“…Regarding the method of detection and differentiation of NDV used in this study, it has been documented that although RT‐PCR and RRT‐PCR cannot replace the virus isolation completely, they are recommended for surveillance programs technique and are useful for rapid screening of at‐risk poultry flocks (Abd‐Elfatah et al., 2021; Camenisch et al., 2008; Wise et al., 2004). The positive cases of waterfowl to Newcastle virus as observed in this study (Table 5) are much higher than previously reported from exotic zoo birds in Tehran (Madadgar et al., 2013) but less than that reported from aquatic birds in Khuzestan province (Talazade & Mayahi, 2013).…”