2009 Annual Report 1a.Objectives (from AD-416) To investigate fundamental poultry host immune response important to control poultry diseases of economic importance and to develop alternative control strategies to enhance mucosal innate immunity of poultry. 1b.Approach (from AD-416) We will investigate host immune response to clostridium infection in broiler chickens using various in vitro and in vito immunological and molecular biological assays. Immune parameters affecting local host immune response to gut pathogens such as lymphocyte subpopulations and cytokine response will be examined using molecular biological and immunological tools. 3.Progress Report The major objectives of this collaboration are:. 1)to investigate immunomodulatory effects of direct-fed microbials (DFMs) on chicken innate immunity,. 2)to study host-pathogen immunobiology of clostridium infections, and. 3)to develop a logical strategy to control gangrene dermatitis (GD). In this reporting period, we have evaluated immunomodulatory effects of nine different DFMs from Danisco/Agtech company and characterized their bioactivity with respect to their macrophage and lymphocyte stimulating effects using in vitro immunoassays. The results are being evaluated and papers are being prepared. Another aspect of this collaboration is the investigation of host immune response to Clostridium in field GD outbreak in Maryland. Various tissues from GD-infected birds were obtained and are being subjected to various immunological analysis to study host-pathogen immunobiology. This collaboration was monitored by regular meetings and progress reports.