Submitted to: World Journal of Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2011
Publication Date: 2/21/2012
Citation: Chang, S., Dunn, J.R., Heidari, M., Lee, L.F., Ernst, C.W., Song, J., Zhang, H. 2012. Vaccine by chicken line interaction alters the protective efficacy against challenge with a very virulent plus strain of Marek's disease virus in white leghorn chickens. World Journal of Vaccines. 2(1):1-11. Available: http://www.scirp.org/journal/wjv/. Interpretive Summary: Marek’s disease (MD) is a lymphoproliferative disease of domestic chickens caused by Marek’s disease virus (MDV), an oncogenic and highly contagious herpesvirus. MD has been controlled by vaccination but sporadic outbreaks of MD continue occurring in some parts of the world. Therefore, efforts seeking to improve vaccine protective efficacy is indeed warranted and continued. Data from this study confirms both chicken line and type of vaccines are important factors affecting protective efficacy. More interesting, our data show the less expensive MD vaccine, HVT, protects genetically resistant lines of chickens better or equally well than CVI988/Rispens, the most commonly used and more expensive MD vaccine. The ranking of MD incidences was altered between the relative resistant and the highly susceptible chicken lines in most trials due to vaccination. These findings are of important implications in vaccine development and usage.
Technical Abstract: Marek’s disease (MD) is a lymphoproliferative disease of domestic chickens caused by Marek’s disease virus (MDV), an oncogenic and highly contagious a-herpesvirus. MD has been controlled by vaccination but sporadic outbreaks of MD still occur in some parts of the world. Efforts to improve vaccine efficacy have continued in both research commu-nities and vaccine industries. We reported the host genetic variation affecting Marek’s disease vaccine-induced immu-nity in chickens earlier. In this study, we evaluated chicken lines, vaccines, and line by vaccine interaction on the pro-tective efficacy of vaccination against MD. Specific pathogen free chickens from the relatively resistant line 63 and the highly susceptible line 72 were primarily used to evaluate the protection by three kinds of vaccines (rMd5'Meq, CVI988/Rispens, and HVT) upon challenge with a very virulent plus strain of MDV, vv+648A. Our data confirmed that both the chicken line and the vaccine significantly affected the protective efficacy of vaccination and showed that a chicken line by vaccine interaction, in most of the trials, also altered vaccine protective efficacy. More interestingly, although the protective index of all vaccine strains was higher in resistant than in susceptible line of chickens, the dif-ference for HVT protection was striking and warrants further study. The findings may have important implications for vaccine development as well as for selective use of particular vaccines in specific lines of chickens to achieve maxi-mum protection at minimized costs.