Deoxyribonucleic acid segment from a virus

Process for the production of a DNA molecule containing transcription enhancer DNA from the upstream region of the major immediate early (IE) gene of murine cytomegalovirus (MCMV) or an enhancer-active mutant thereof, and optionally promoter sequences or other flanking sequences, characterized in

• (a) fragmenting DNA molecules from the IE region of MCMV or purified total MCMV, cotransfecting the obtained DNA fragments with enhancerless genomes of another virus into eukaryotic cells, isolating from the transfected cells viable recombinant viruses containing DNA molecules showing enhancer activity and isolating from the obtained viral DNA the inserted DNA originating from MCMV, or
• (b) determining the structure of the inserted MCMV DNA molecule and synthesizing the inserted MCMV DNA molecule, an enhancer-active fragment or enhancer-active mutant thereof,
• (c) or fragmenting purified total MCMV DNA or DNA molecules from the IE region of the MCMV DNA by sonication or by treatment with at least one restriction enzyme or optionally an exonuclease, optionally followed by treatment with a DNA polymerase, optionally followed by cloning in a suitable vector, whereby the enhancer DNA is identified by hybridization to DNA containing a sequence of the IE enhancer or IE promoter.

A recombinant DNA molecule containing transcription enhancer DNA from the upstream region or the major immediate early (IE) gene of murine cytomegalovirus (MCMV) or an enhanceractive mutant thereof, and optionally promoter sequences or other flanking sequences.

A recombinant DNA molecule with comprise a nucleotide sequence encoding to heterologous protein operatively linked to the approximately 2.27 kilobase pair PstI restriction, fragment of the MCMV genome containing the mouse cytomegalovirus (MCMV) immediate early promoter or to an effective expression promoting fragment thereof.

A process for improving eukaryotic expression systems, which comprises incorporation of a DNA molecule containing transcription enhancer DNA from the upstream region of the major immediate early (IE) gene of murine cytomegalovirus (MCMV) or an enhancer active mutant thereof upstream or downstream of a structural gene or of the regulation region.

A process for improving eukaryotic expression systems, which comprises incorporation of a DNA molecule containing transcription enhancer DNA from the upstream region of the major immediate early (IE) gene of murine cytomegalovirus (MCMV) or an enhancer-active mutant thereof upstream or downstream of a structural gene or of the regulation region.