The present invention relates to recombinant modified vaccinia Ankara (MVA) virus containing restructured sites useful for the integration of heterologous nucleic acid sequences into an intergenic region (IGR) of the virus genome, where the IGR is located between two adjacent, essential open reading frames (ORFs) of the vaccinia virus genome, wherein the adjacent essential ORFs are non-adjacent in a parental MVA virus used to construct the recombinant MVA virus, and to related nucleic acid constructs useful for inserting heterologous DNA into the genome of a vaccinia virus, and further to the use of the disclosed viruses as a medicine or vaccine.
