2012 Annual Report 1a.Objectives (from AD-416): To evaluate the potency of defined synthetic nucleic acid compounds (ORN/ODN) compounds as vaccine adjuvants to enhance the efficacy of killed Streptococcus vaccines for use in Aquaculture. 1b.Approach (from AD-416): The innate immune system of vertebrates has evolved the ability to recognize unmethylated CG dinucleotides within certain sequence contexts (CpG motifis) in bacterial and some viral DNA. The effect or potency of immunostimulatory CpG compounds (oligodeoxynucleotides [ODNs] and oligoribonucleotides [ORNs]) for the two inactivated Streptococcus vaccines will be evaluated in vitro using catfish head kidney (HK) cells or peritoneal macrophages. The effect or potency of CpG compounds (ORN or ODN) for the two inactivated Streptococcus vaccines will then be evaluated in vivo using Nile tilapia Oreochromis niloticus. The efficacy of different formulations of inactivated vaccines will then be evaluated using Nile tilapia, Oreochromis niloticus. Safety and efficacy tests will be performed using methods routinely used by ARS. 3.Progress Report: The objective of this Trust Fund Cooperative Research Agreement is to evaluate the potency of defined synthetic nucleic acid compounds oligodeoxynucleotides/oligoribonucleotides (ORN/ODN)as vaccine adjuvants to enhance the efficacy of killed streptococcus vaccines for use in aquaculture. Potency of seven ODN/ORN as adjuvants for killed Streptococcus iniae vaccine has been evaluated by the ARS scientists at Auburn, AL, and the results have been sent to the cooperator. In addition, the molecular mechanisms involved in the protection elicited by ODN/ORN in Nile tilapia have been investigated and genes induced by ODN/ORN in Nile tilapia have been identified. Upregulated genes have been submitted to GenBank. These results suggest that adjuvant could be used to increase the efficacy of DNA vaccines. ARS PI monitoring activities to evaluate research progress included: phone calls, conference calls, email communications.