The proposed work is to generate broadly-protective influenza virus vaccines. The basic experimental approach that we will use to accomplish the goal of vaccine generation is divided into two phases. Aim 1 involves characterization of human and murine monoclonal antibodies with broad protective activity against hemagglutinins of distinct influenza virus strains. Efforts will be made to determine the precise region of binding of these broadly-protective antibodies on the hemagglutinin molecule. Aim 2 of this work will involve the design and production of novel vaccine constructs that focus immunity towards those epitopes determined to mediate broad protection. We will construct a set of novel immunogens: several will be based on conserved, continuous, polypeptidic regions of the hemagglutinin, others are based on conformational, discontinuous moieties or on chimeric hemagglutinins. The vaccination strategies will involve the use of DNA, recombinantly purified protein or purified (chimeric) virus. In collaboration with Projects 2 and 3, the vaccine constructs will be optimized by use of complementary adjuvant preparations and will be evaluated for efficacy in both mouse and in ferret models of disease. RELEVANCE (See instructions): Present influenza virus vaccines have to be newly manufactured every year because the circulating influenza virus strains are continuously changing. We are attempting to design novel universal influenza virus vaccines which would be cross-protective against different strains and thus last longer, avoiding the necessity of annual revaccinations; this will be done by first identifying cross-protective monoclonal antibodies (directed against the viral hemagglutinin) and the precise epitopes/sequences they recognize. These epitopes will then be used to guide the design of vaccine constructs which induce cross-protective immune responses against many different influenza virus variants.