Location: Endemic Poultry Viral Diseases ResearchTitle: Depletion of CD8aß+ T cells in chickens demonstrates their involvement in protective immunity towards Marek’s disease with respect to tumor incidence and vaccinal protection
Submitted to: Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2020
Publication Date: 9/24/2020
Citation: Umthong, S., Dunn, J.R., Cheng, H.H. 2020. Depletion of CD8aß+ T cells in chickens demonstrates their involvement in protective immunity towards Marek’s disease with respect to tumor incidence and vaccinal protection. Vaccines. 8(4):557. https://doi.org/10.3390/vaccines8040557.
Interpretive Summary: Marek's disease is a T cell cancer of chickens induced by the Marek's disease virus, a cancer-causing herpesvirus, and a serious economic problem for the poultry industry. Currently, MD is controlled primarily by widespread vaccination, however, recurrent and unexpected disease outbreaks frequently occur. Thus, efforts are needed to provide more efficient vaccines. In this paper, we examined the role that CD8 T cells, which are responsible for killing virally-infected cells, play in viral pathogenesis and vaccinal protection. We found that CD8 T cell are important in both reducing tumor formation and enhancing vaccinal protection. This information will be valuable to vaccine manufacturers in designing more protective MD vaccines, which will result in more affordable poultry products to consumers and enhanced animal welfare.
Technical Abstract: Marek’s disease (MD) is a lymphoproliferative disease in chickens caused by Marek’s disease virus (MDV), a highly oncogenic alphaherpesvirus. Since 1970, MD has been controlled through widespread vaccination of commercial flocks. However, repeated and unpredictable MD outbreaks continue to occur in vaccinated flocks, indicating the need for a better understanding of MDV pathogenesis to guide improved or alternative control measures. As MDV is an intracellular pathogen that infects and transforms CD4+ T cells, the host cell-mediated immune response is considered to be vital for controlling MDV replication and tumor formation. In this study, we addressed the role of CD8+ T cells in vaccinal protection by widely-used monovalent (SB-1 and HVT) and bivalent (SB-1+HVT) MD vaccines. We established a method to deplete CD8+ T cells in chickens and found that their depletion through injection of anti-CD8 monoclonal antibodies (mAb) increased tumor induction and MD pathology, and reduced vaccinal protection to MD, which supports the important role of CD8+ T cells for both MD and vaccinal protection.