Influenza A virus causes significant morbidity in swine, resulting in a substantial economic burden. Vaccination is the primary method for the prevention of influenza disease. Live virus vaccines provide superior immunity to that induced by conventional inactivated vaccines. Currently, there are no live vaccines available for swine influenza. The objective of this project is to develop live virus vaccine against swine influenza. We have generated one virus which is weakened in replication. The weakened form of virus was able to grow in the tissue culture system, thus facilitating production of this virus. When tested in pigs, this virus could infect pigs without causing disease. Hence, this virus is a great candidate to serve as live vaccine. Immune response to this virus and immune protection to other swine influenza virus challenge are being assessed.