Production of single-stranded DNA in mammalian cells by means of a bacterial retron.

msDNA-Ec67, a peculiar multicopy single-stranded DNA of a specific sequence was produced in NIH3T3 mouse cells. Retron-Ec67, a retroelement from Escherichia coli, was introduced under the T7 polymerase promoter and the non-translated 5'-region of the encephalomyocarditis virus. The construct was then transfected into the NIH3T3 cells constitutively producing T7 RNA polymerase. Forty-eight hours after transfection, msDNA-Ec67 was detected in the cells by means of Southern blot hybridization and reverse transcriptase extension assay. The potential use of bacterial retrons as a vector for single-stranded DNA production in mammalian cells is discussed.