Deletion of the Viral Thymidine Kinase in a Meq-Deleted Recombinant Marek’s Disease Virus Reduces Lymphoid Atrophy but Is Less Protective

Autor: Steven J. Conrad, Eniope B. Oluwayinka, Mohammad Heidari, Jody K. Mays, John R. Dunn
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Microorganisms, Vol 10, Iss 1, p 7 (2021)
Druh dokumentu: article
ISSN: 2076-2607
DOI: 10.3390/microorganisms10010007
Popis: Marek’s disease (MD) is a ubiquitous disease of domesticated chickens and its etiologic agent is the Gallid alphaherpesvirus 2 (GaHV-2), also known as Marek’s disease virus (MDV). MD is currently controlled by vaccination using live attenuated strains of MDV (e.g., CVI988/Rispens), non-pathogenic serotypes of MDV (GaHV-3), or non-pathogenic strains of the related Melagrid alphaherpesvirus 1 (MeHV-1). One attractive strategy for the production of new vaccine strains is a recombinant MDV attenuated by the deletion of the major viral oncogene meq. However, meq-deleted variants of MDV cause atrophy of the bursa and thymus in maternal antibody-negative chickens, and the resulting immunosuppression makes them unsuitable. Herein we detail our attempt to mitigate the lymphoid atrophy caused by meq-deleted MDV by further attenuation of the virus through ablation of the viral thymidine kinase (tk) gene. We demonstrate that ablation of the viral tk from the meq-deleted virus rMd5B40/Δmeq resulted in a virus attenuated for replication in vitro and which spared chickens from atrophy of the lymphoid organs in vivo. When the rMd5B40/Δmeq/Δtk/GFP was used as a vaccine it was protective against challenge with the vv+MDV strain 686, but the protection was less than that provided by the CVI988/Rispens vaccine.
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