Abstract: The invention relates to vectors produced in a donor host cell, which upon transfer into a receiver host cell maintain the desired expression of the nucleotide sequences that are located within the vector. The maintenance of the desired expression is achieved because the vector at least partly remains unmethylated within the receiver host cell. The donor host cell is different as compared to the receiver host cell and the receiver host cell being capable of methylating DNA. The invention also relates to methods for the production of such vectors and the use of the vectors in industry as well as in medicine.