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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Endemic Poultry Viral Diseases Research » Research » Publications at this Location » Publication #380562

Research Project: Genetic and Biological Determinants of Avian Herpesviruses Pathogenicity, Transmission, and Evolution to Inform the Development of Effective Control Strategies

Location: Endemic Poultry Viral Diseases Research

Title: Deletion of thymidine kinase reduces protection of Marek’s disease vaccine candidate

item Dunn, John
item Conrad, Steven
item OLUWAYINKA, ENIOPE - Federal University Of Agriculture, Abeokuta
item Mays, Jody
item Heidari, Mohammad

Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2021
Publication Date: 7/30/2021
Citation: Dunn, J.R., Conrad, S.J., Oluwayinka, E., Mays, J.K., Heidari, M. 2021. Deletion of thymidine kinase reduces protection of Marek’s disease vaccine candidate. American Association of Avian Pathologists. Deletion of thymidine kinase reduces protection of Marek's disease vaccine candidate [abstract].

Interpretive Summary:

Technical Abstract: Recent attempts to develop improved vaccines for the prevention of Marek’s disease (MD) have focused upon recombinant Marek’s disease viruses (MDVs) in which various genes have been deleted with the intent of reducing MDV virulence while retaining its potency as an immunogen. One such construct, a MDV with deleted Meq gene, has been shown to be an effective vaccine but with the undesirable characteristic of lymphoid atrophy. Previous attempts have been unsuccessful in eliminating the lymphoid atrophy while retaining superior protection of this vaccine candidate. Disruption/ablation/deletion of the viral thymidine kinase (TK) has long been a reliable method of viral attenuation, often producing herpesvirus vaccine strains which are stable, of greatly reduced pathogenicity, and efficacious. We hypothesized that a combined Meq and TK-deleted virus may have sufficient attenuation to allow for viral replication in vivo with absence of lymphoid atrophy. While we were successful in eliminating lymphoid atrophy, unfortunately this came at the cost of reduced virus protection in chickens challenged with vv+MDV.