Gene targeting by adeno-associated virus vectors is cell-cycle dependent

Adeno-associated virus (AAV) vectors can be used to introduce site-specific mutations into homologous chromosomal sequences. There are many potential applications of this technique, but the process of AAV-mediated gene targeting and factors that influence targeting efficiency are not completely understood. We investigated the dependence of AAV-mediated gene targeting on the host cell-cycle status. The frequency of gene targeting by AAV vectors was compared in dividing and serum-arrested normal human fibroblast cultures. Gene targeting occurred in arrested fibroblast cultures at 0.15 to 1.1% the frequency of dividing cultures, and only took place in cells that had undergone DNA synthesis. Gene targeting was also reduced when DNA synthesis was inhibited by hydroxyurea.