The present invention provides a linear expression construct free of any conventional amplification and/or selection sequences comprising an RNA polymerase I (poll) promoter and a poll termination signal, inserted between a RNA polymerase Il (polll) promoter and a polyadenylation signal useful for the expression of segments of viral RNA, preferably influenza viruses. The inventive construct is useful for efficient and fast production of viral particles, especially for producing vaccine formulations for the treatment of epidemic and/or pandemic diseases.