Circulating hypervirulent Marek’s disease viruses in vaccinated chicken flocks in Taiwan by genetic analysis of meq oncogene

• Published in: PloS one Vol. 19; no. 5; p. e0303371
• Main Authors: Cheng, Ming-Chu, Lai, Guan-Hua, Tsai, Yi-Lun, Lien, Yi-Yang
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.05.2024; Public Library of Science (PLoS)
• Subjects: Amino acids; Animal diseases; Animals; Chickens; Chickens - virology; China; Circulation; Cloning; Disease control; Economic impact; Epidemics; Genes; Genetic analysis; Health aspects; Herpesvirus 2, Gallid - genetics; Herpesvirus 2, Gallid - pathogenicity; Japan; Livestock farms; Lymphoma; Marek Disease - prevention & control; Marek Disease - virology; Marek Disease Vaccines - genetics; Marek Disease Vaccines - immunology; Marek's disease; Medicine; Oncogene Proteins, Viral - genetics; Oncogenes; Ovaries; Pathogens; Phylogenetics; Phylogeny; Poultry; Poultry Diseases - epidemiology; Poultry Diseases - prevention & control; Poultry Diseases - virology; Poultry farming; Practice; Strains (organisms); Taiwan; Taiwan - epidemiology; Thailand; Vaccination; Vaccination - veterinary; Vaccines; Virulence; Virulence (Microbiology); Virulence - genetics; Viruses; Taiwan; Thailand; Japan; China; United States > US; India
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0303371

Marek’s disease (MD) is an important neoplastic disease caused by serotype 1 Marek’s disease virus (MDV-1), which results in severe economic losses worldwide. Despite vaccination practices that have controlled the MD epidemic, current increasing MD-suspected cases indicate the persistent viral infections circulating among vaccinated chicken farms in many countries. However, the lack of available information about phylogeny and molecular characterization of circulating MDV-1 field strains in Taiwan reveals a potential risk in MD outbreaks. This study investigated the genetic characteristics of 18 MDV-1 strains obtained from 17 vaccinated chicken flocks in Taiwan between 2018 and 2020. Based on the sequences of the meq oncogene, the phylogenetic analysis demonstrated that the circulating Taiwanese MDV-1 field strains were predominantly in a single cluster that showed high similarity with strains from countries of the East Asian region. Because the strains were obtained from CVI988/Rispens vaccinated chicken flocks and the molecular characteristics of the Meq oncoprotein showed features like vvMDV and vv+MDV strains, the circulating Taiwanese MDV-1 field strains may have higher virulence compared with vvMDV pathotype. In conclusion, the data presented demonstrates the circulation of hypervirulent MDV-1 strains in Taiwan and highlights the importance of routine surveillance and precaution strategies in response to the emergence of enhanced virulent MDV-1.