The present invention relates to the cloning of nucleic acid molecules and the production of nucleic acid libraries, as well as the expression of recombinant proteins and bactofection. More in particular, the invention relates to a method of inducing and expressing nucleic acid in an animal cell, the method comprising: (a) providing a vector comprising an insertion site, a first origin of replication a second origin of replication, and a pair of transcriptional terminators (b) introducing the nucleic acid into the insertion site of the vector (c) transforming at least one invasive bacterium with the vector to form at least one transformed bacterium and (d) infecting the animal cell with said at least one transformed bacterium.
