Self-complementary sequences induce the formation of double-stranded filamentous phages.

The single strand nature of the filamentous phage (Ff) genome is currently one of the main drawbacks for their application as gene delivery vectors. In this work, by the incorporation of inverted self complementary sequences into the genome of Ff, we were able to convert single strand genome of Ff into double strand DNA structures. The presence of self complementary sequences in phage genome did not affect viral yields significantly, and the formation of double strands structures was successfully determined by a Mung Bean Nuclease resistance assay. Upon transfection into HEK293 cells, the double strand DNA structures showed to be readable by the transcriptional machinery of mammalian cells.