Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2011
Publication Date: 7/19/2011
Citation: Chang, S., Dunn, J.R., Lee, L.F., Heidari, M., Song, J.Z., Ernst, C.W., Zhang, H.M. 2011. The protective efficacy of rMd5deltaMeq against challenge with a very virulent plus strain of MDV in relatively resistant lines of chickens [abstract]. Poultry Science Association/American Association of Avian Pathologists Abstracts, July 16-19, 2011, St. Louis, Missouri. p. 124. Interpretive Summary:
Technical Abstract: Marek’s disease (MD) is a T-cell lymphoma of domestic chickens induced by MD virus (MDV), a naturally oncogenic and highly contagious cell-associated alpha-herpesvirus. A recombinant MDV lacking both copies of Meq oncogene, rMd5deltaMeq, was tested as a candidate vaccine against MD in a series of 19 recombinant congenic strains (RCS) of chickens. Early reports suggest that rMd5deltaMeq provides protection equally well or better than commonly used MD vaccines in susceptible experimental and commercial lines of chickens challenged with very virulent plus (vv+) strains of MDV. In this study, protection was assessed using maternal antibody positive chickens from 19 relatively resistant RCS in trial 1 and maternal negative chickens from 14 of the 19 RCS in trial 2. In both trials, chickens from each RCS were divided into three treatment groups. The first two groups were vaccinated either with rMd5deltaMeq or CVI988/Rispens on the day of hatch followed by challenge with a vv+ strain of MDV, 648A, on the fifth day post hatch. The third group was not vaccinated but challenged with the same virus. The protection indices among the RCS ranged from 43-100% and 42-95% for rMd5deltaMeq, 6-83% and 40-70% for CVI988/Rispens for trials 1 and 2, respectively. Our findings from this study provide experimental evidence that rMd5deltaMeq protects significantly better than the CVI988/Rispens (P<0.01) in relatively resistant lines of chickens against vv+ MDV. Together with earlier reports, rMd5deltaMeq appeared to be a better vaccine, compared with the most commonly used commercial vaccine, CVI988/Rispens, for control of MD in lines of chickens regardless of their genetic background or maternal antibody status.