2012 Annual Report 1a.Objectives (from AD-416): To identify genetic and epigenetic factors, markers, causal genes, or DNA methylation signatures that are underlying of genetic resistance to the viral induced poultry disease. 1b.Approach (from AD-416): Michigan State University (MSU) will provide expertise on genetic and epigenetic analysis in the joint effort to identify the genetic and epigenetic factors using genetic resources at ADOL. MSU will also help to conduct Marek’s disease virus challenge trials, and take varied samples including blood samples, prepare DNA and RNA samples, to conduct necropsy of experimental birds, and in subsequent lab and data analyses of the project. 3.Progress Report: This project is directly linked to 3635-31320-008-34R titled “The Epigenetic Landscape for Marek’s Disease Susceptibility and Resistance in Chickens.” A challenge trial was repeated with two highly inbred lines of chickens to evaluate non-MHC genetic variation impact on vaccinal protective efficacy. The data confirmed previous findings that 1). Host genetics plays a significant role in modulating vaccine protective efficacy; 2). Herpesvirus of turkeys (HVT), a low efficacy MD vaccine, protects relatively resistant chickens to MD equally well in comparison with more efficacious ones. A third challenge trial was also conducted during the year using birds from two reciprocal crosses, a line 6 by line 7 cross and a line 7 by line 6 cross. CD4 cells were isolated from blood samples for epigenetic analyses including DNA methylation patterns, histone modifications, and microRNA profiling.