The development of transient SV40 based shuttle vectors for mutagenesis studies: problems and solutions

Shuttle-vector plasmids would appear to provide a powerful technology for studying mutagenesis in mammalian (including human) cells. Recently, as described in this and other papers in this volume, several shuttle-vector systems have been described and applied. The development of the first shuttle vectors for these purposes was hindered by two major problems. The first of these was the 'poison' sequence present in many pBR322 based vectors. The second was the problem of spontaneous mutagenesis associated with transfection of the plasmids into mammalian cells. Effective solutions for both problems have been devised, and it is now possible to experimentally address a variety of questions concerning mutagenesis and repair in mammalian cells.