Poxviruses as expression vectors are widely used in medical research for the development of recombinant vaccines and molecular therapies.Here we report about recent accomplishments in vaccine research using recombinant Modified Vaccinia virus Ankara (MVA).MVA is a highly attenuated vaccinia virus strain that originated from serial tissue culture passage in chicken embryo fibroblasts more than 40 years ago.Growth adaptation to avian host cells caused deletions and mutations in the viral genome affecting about fifteen percent of the original genetic information.