Molecular and pathological characterisation of genotype VII Newcastle disease virus on Egyptian chicken farms during 2016–2018

Abstract

Newcastle disease virus (NDV) remains a constant threat to the poultry industry even with intensive vaccination programmes. In the present study, 40 samples were collected from farms showing high mortalities in some Egyptian governorates between 2016 and 2018. Tracheal samples were collected for virus isolation and confirmed by real-time RT-PCR. Molecular characterisation was performed by sequencing, followed by phylogenetic analysis of the novel sequences. Histopathological and immunohistochemical examinations were performed on different organs from NDV-infected broilers. The phylogenetic analysis revealed that the NDV isolates from different areas of Egypt were genetically closely related and all belonged to genotype VII. The histopathological hallmarks included haemorrhagic tracheitis, interstitial pneumonia with syncytia formation, haemorrhagic proventriculitis, necrotising pancreatitis, pan-lymphoid depletion, non-suppurative encephalitis and nephritis. Immunological detection of NDV antigen clarified the widespread presence of viral antigen in different organs with severe lesions. The present study confirmed that a virulent NDV of genotype VII became the predominant strain, causing severe outbreaks in poultry farms in Egypt. The presence of viral antigen in different organs indicates the pantropic nature of the virus. Immunohistochemistry was a very useful diagnostic tool for the detection of NDV antigen.

Contribution of mutation I142M in fusion protein and Q44R in matrix protein of Newcastle disease virus to virulence in ducks

“…Cell-cell fusion in vivo is presumed to be associated with the virulence of other paramyxoviruses, such as measles virus and Sendai virus [27,29]. Syncytia has also been reported in the bronchial lumen of chickens infected with velogenic NDV [32]. It will be interesting to verify whether the increased fusion activity by F I142M is linked to syncytium formation in vivo.…”

Protective effectiveness of two vaccination schemes against the prevalent Egyptian strain of Newcastle disease virus genotype VII

“…Regarding macro and microscopic findings, the dead birds in the unvaccinated group (G–C) showed typical gross and histological lesions associated with NDV infection ( Ewies et al , 2017 ; Mousa et al , 2020 ; EL-Morshidy et al , 2021 ; Sultan et al , 2021b ) with noted atrophied lymphoid organs as thymus, bursa, and spleen in 50%–95.8% of birds and associated microscopically with depletion of lymphocytes, which is common with virulent viscerotropic NDV ( Wakamatsu et al , 2006 ; EL-Morshidy et al , 2021 ). Furthermore, it is worth noting that 70.8% of the dead birds had severe central nervous system lesions as well as pancreatitis, such findings were reported among recent NDV genotype VII isolates ( Mousa et al , 2020 ; EL-Morshidy et al , 2021 ). The involvement of nervous signs that are explained by severe macro and micro pathological lesions and damage to cerebellar neuronal suggest caudal viral propagation and neurotropism, which are frequent in velogenic neurotropic NDV ( Cattoli et al , 2011 ; Suarez et al , 2020 ; EL-Morshidy et al , 2021 ).…”

Possible Outbreak of Newcastle Virus Infection in the Face of Increasing Trend of Backyard Poultry Farm Management Interface in Nigeria: A Public Health and Food Security Threat

“…Recent reports of NDV outbreaks come from Vietnam, Indonesia, Malaysia, and Cambodia [77]. The poultry sector is currently seriously threatened by genotype VII NDV, which is endemic in several countries in Asia and Africa [78][79][80].…”