Influenza virus vaccine composition and methods of use

The present invention is directed to compositions and methods for enhancing the immune response of a human in need of protection against influenza virus (IV) infection by administering in vivo, into a tissue of the human, at least one polynucleotide comprising one or more regions of nucleic acid encoding an IV protein or a fragment, a variant, or a derivative thereof, or a protein encoded thereby. The polynucleotide is incorporated into the cells of the human in vivo, and an immunologically effective amount of an immunogenic epitope of an IV, or a fragment, variant, or derivative thereof is produced in vivo. The IV protein (in purified form or in the form of an inactivated IV vaccine) is also administered in an immunologically effective amount.