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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 #346527

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: Marek’s disease vaccine activates macrophages

item Wang, Dan - Shandong Agricultural University
item Sun, Shuhang - Shandong Agricultural University
item Heidari, Mohammad - US Department Of Agriculture (USDA)

Submitted to: Journal of Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2018
Publication Date: 5/31/2018
Citation: Wang, D., Sun, S., Heidari, M. 2018. Marek’s disease vaccine activates macrophages. Journal of Veterinary Science. 19(2018):375-383.

Interpretive Summary: Marek's disease virus (MDV), a highly cell-associated oncogenic alpha-herpes virus, is the etiological agent of Marek's disease (MD), a contagious lymphoproliferative disease of domestic chickens. Although MD vaccines have been in use for more than four decades, the specific mechanism of vaccine-induced protection is not clear. MD remains as a major economic threat to the poultry industry and consequently, elucidation of immune mechanisms of vaccine-mediated immunity is of critical importance. The purpose of the present study was to investigate the role of macrophages in CVI988/Ripens-mediated protection in two MD-susceptible and resistant chicken lines. Differential expression of macrophage-specific genes in the cecal tonsils, duodenum, and macrophages isolated from spleen of the vaccinated birds revealed activation of macrophages and a robust innate immune response to vaccination. Absence of an increase in the population of T cells in the tested tissues of the vaccinated birds at days 3 and 5 post-vaccination was suggestive of lack of an involvement of adaptive immune responses to the early stages of vaccination. Additionally, significant replication of the vaccine strain virus in the cecal tonsils and duodenum of the vaccinated susceptible line was detected by a Rispens-specific monoclonal antibody at day 5 post-vaccination. Moreover, the macrophage population was substantially increased in the duodenum of vaccinated susceptible and resistant chicken lines at the same time point when compared to the age and line-matched control birds. This study provides further insight into the role of the innate immune system in vaccine-induced protection and possible development of new recombinant vaccines with enhanced innate immune system activation properties.

Technical Abstract: To provide insights into the role of innate immune responses in vaccine-mediated protection, we investigated the effect of Marek’s disease (MD) vaccine, Rispens/CVI988, on the expression pattern of select genes associated with activation of macrophages in MD-resistant and susceptible chicken lines. Up regulation of IFN-gamma, IL-1beta, IL-8, and IL-12 at different time points post immunization (dpi) revealed activation of macrophages in both chicken lines. Stronger immune response was induced in the cecal tonsils of the susceptible line at 5 dpi. The highest transcriptional activities were observed in the spleen tissues of the resistant line at 3 dpi. No increase in the population of CD3+ T cells was observed in duodenum of vaccinated birds at 5 dpi indicating the lack of involvement of adaptive immune system in the transcriptional profiling of the tested genes. There was, however, an increase in the number of macrophages in the duodenum of vaccinated birds. The CVI988/Rispens antigen was detected in the duodenum and cecal tonsils of the susceptible line but not the resistant line at 5 dpi. This study sheds light on the role of macrophages in vaccine-mediated protection against MD and possible development of new recombinant vaccines with enhanced innate immune system activation properties.