{"title":"Gallid Alphaherpesvirus 2 in the Egyptian Turkeys: Molecular Characterization and Establishment of a Universal System for Phylogenetic Classification.","authors":"Mahmoud Bayoumi, Mohamed El-Saied, Basem Ahmed, Magdy El-Mahdy, Haitham Amer","doi":"10.1159/000515904","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>Gallid alphaherpesvirus 2 (GaHV-2) is a highly contagious oncogenic virus that causes Marek's disease in chickens and occasionally in turkeys. Among 100 genes identified in GaHV-2 genome, the Meq gene appears to involve viral virulence, oncogenicity, and genetic diversity. Despite the use of Meq gene sequences in phylogenetic classification of GaHV-2 strains circulating in many countries worldwide, no integrated system exists yet.</p><p><strong>Methods: </strong>Turkeys from 2 commercial Egyptian farms were presented with signs of dullness, dehydration, and emaciation. Samples prepared from the internal organs were examined by histopathology and immunohistochemistry. Pools of the internal organs were analyzed by PCR for identification of GaHV-2, avian leucosis virus, and reticuloendotheliosis virus. The Meq gene of an Egyptian strain was sequenced and analyzed in comparison to 40 reference strains for generation of a universal system for phylogenetic classification of GaHV-2 strains.</p><p><strong>Results: </strong>Gross and histopathological examination revealed grayish-white soft masses in the internal organs characterized by diffuse infiltration of pleomorphic neoplastic cells. All lymphoma cells were identified as T-lymphocytes of CD3+ phenotype. Samples of both farms were only positive for GaHV-2 by PCR. Sequence analysis of the Meq gene has classified the current turkey strain as related to the Egyptian strains identified in chicken in 2012. A universal phylogenetic system for classification of GaHV-2 strains into 4 clusters was proposed. The vaccine strains were all grouped in cluster 2, and most of the classical American strains belonged to cluster 4. Cluster 1 was further divided into 3 subclusters (1.1-1.3).</p><p><strong>Conclusion: </strong>GaHV-2 was identified in turkeys for the first time in Africa and the Middle East. Sequence analysis of the Meq gene of the Egyptian strain along with a wide array of the global strains has enabled the construction of a novel phylogenetic classification system.</p>","PeriodicalId":14547,"journal":{"name":"Intervirology","volume":null,"pages":null},"PeriodicalIF":3.2000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1159/000515904","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Intervirology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1159/000515904","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2021/5/21 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"VIROLOGY","Score":null,"Total":0}
引用次数: 2
Abstract
Introduction: Gallid alphaherpesvirus 2 (GaHV-2) is a highly contagious oncogenic virus that causes Marek's disease in chickens and occasionally in turkeys. Among 100 genes identified in GaHV-2 genome, the Meq gene appears to involve viral virulence, oncogenicity, and genetic diversity. Despite the use of Meq gene sequences in phylogenetic classification of GaHV-2 strains circulating in many countries worldwide, no integrated system exists yet.
Methods: Turkeys from 2 commercial Egyptian farms were presented with signs of dullness, dehydration, and emaciation. Samples prepared from the internal organs were examined by histopathology and immunohistochemistry. Pools of the internal organs were analyzed by PCR for identification of GaHV-2, avian leucosis virus, and reticuloendotheliosis virus. The Meq gene of an Egyptian strain was sequenced and analyzed in comparison to 40 reference strains for generation of a universal system for phylogenetic classification of GaHV-2 strains.
Results: Gross and histopathological examination revealed grayish-white soft masses in the internal organs characterized by diffuse infiltration of pleomorphic neoplastic cells. All lymphoma cells were identified as T-lymphocytes of CD3+ phenotype. Samples of both farms were only positive for GaHV-2 by PCR. Sequence analysis of the Meq gene has classified the current turkey strain as related to the Egyptian strains identified in chicken in 2012. A universal phylogenetic system for classification of GaHV-2 strains into 4 clusters was proposed. The vaccine strains were all grouped in cluster 2, and most of the classical American strains belonged to cluster 4. Cluster 1 was further divided into 3 subclusters (1.1-1.3).
Conclusion: GaHV-2 was identified in turkeys for the first time in Africa and the Middle East. Sequence analysis of the Meq gene of the Egyptian strain along with a wide array of the global strains has enabled the construction of a novel phylogenetic classification system.
期刊介绍:
''Intervirology'' covers progress in both basic and clinical virus research, and aims to provide a forum for the various disciplines within virology. Issues publishing original papers alternate with thematic issues, focusing on clearly defined topics. This thematic concentration serves to make timely reviews, research reports and controversy easily accessible to both specialists in the field and those who want to keep track of the latest developments outside their own area of interest. In addition to original papers, regular issues publish short communications and letters to the editor to provide readers with a forum for the exchange of ideas and comments. The scope encompasses work on the molecular biology of human and animal viruses, including genome organization and regulation, and the structure and function of viral proteins. The pathogenesis, immunology, diagnosis, epidemiology, prophylaxis and therapy of viral diseases are considered.