The subject invention concerns methods and materials for inducing an immune response in an animal or person against an immunodeficiency virus, such as HIV, SIV, or FIV. In one embodiment, a method of the invention comprises administering one or more antigens and/or immunogens to the person or animal wherein the antigen and/or immunogen comprises one or more evolutionarily conserved epitopes of immunodeficiency viruses. In one embodiment, the epitope is one that is conserved between HIV and FIV.