Antibodies that bind with high affinity to swine H1N1 virus are described. In vivo experiments showed that one such antibody is able to fully protect mice challenged with a lethal dose of swine H1N1 virus. The antibody is also able to cure mice in a therapeutic setting when treated as late as up to 60 hours (2.5 days) after infection with swine H1N1 virus. Also described are recombinant forms of this antibody.