Molecular characterization and pathogenicity of very virulent infectious bursal disease virus isolated from naturally in
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Molecular characterization and pathogenicity of very virulent infectious bursal disease virus isolated from naturally infected turkey poults in Egypt Samah M. Mosad 1 & Abdelfattah H. Eladl 2
&
Mohamed El-Tholoth 1 & Hanaa S. Ali 3 & Mohamed F. Hamed 4
Received: 1 April 2020 / Accepted: 24 September 2020 / Published online: 1 October 2020 # Springer Nature B.V. 2020
Abstract This study was conducted to investigate the molecular characterization and pathogenicity of very virulent infectious bursal disease virus (vvIBDV) isolated from naturally infected turkey poults and possible spread to chickens. Thirty samples were collected from turkey poults in the vicinity or in the same backyards with chickens suspected to be infected with IBDV and from live bird markets from different localities in Dakahlia governorate, Egypt. There were no obvious clinical signs in tested turkey poults except dehydration and whitish diarrhoea in some birds with no mortality, and post-mortem lesions were observed in few birds as atrophied bursae, nephritis and petechial haemorrhages on thigh muscles. Reverse transcription polymerase chain reaction (RT-PCR), histopathological examination and immunohistochemistry were used for identification of the IBDV. Out of 30 tested samples, 17 samples (56.7%) were positive by RT-PCR. Phylogenetic analysis of VP2 gene of two selected IBDV strains (turkey 1 and turkey 2) showed a close genetic relationship to vvIBDV strains (serotype 1) isolated from chickens in Egypt and other countries with 93.1 to 95.99% identity for turkey 1 strain and 95.54 to 98.51% for turkey 2 strain. Both turkey 1 and turkey 2 strains were closely related to the Nigerian vvIBDV strain isolated from turkeys with 95.78% and 96.37% identity, respectively. Sequence analysis of both strains demonstrated that they have conserved amino acid residues of vvIBDV (I242, I294 and S299) and Y220F amino acid substitution which is very common in Egyptian vvIBDV chicken strains, while Turkey 1 strain has amino acid substitutions at A222P and I256V. Histopathological examination showed marked depletion of bursal lymphoid tissue. In conclusion, for the first time in Egypt, the molecular characterization and pathogenicity confirmed the presence of natural infection of turkey poults with vvIBDV (serotype 1) with possible spread to chickens causing severe economic losses. Keywords Turkeys . vvIBDV . RT-PCR . Sequence analysis . Pathogenicity . Egypt
Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11250-020-02420-5) contains supplementary material, which is available to authorized users. * Abdelfattah H. Eladl [email protected] 1
Department of Virology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
2
Department of Poultry Diseases, Faculty of Veterinary Medicine, Mansoura University, PO Box: 35516, Mansoura, Egypt
3
Department of Pathology, Animal Health Research Institute, Mansoura, Egypt
4
Department of Pathology, Faculty of Veterinary
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