ABSTRACT
The first application of a genetic approach for therapeutic efficacy in humans was launched in 1990. In the seven years following, worldwide clinical trials in at least 15 countries have over 1500 enrolled patients, with a predominant emphasis on the targeting of cancer, AIDS, cystic fibrosis and arterial diseases. Early emphasis was placed on the development and utilization of viral vectors, in particular retroviral-based delivery systems. Other current viral approaches include adenovirus-, adeno-associated virus-, herpes simplex virus-and lentivirus-based systems. In these approaches, unnecessary and undesirable sequences of the genome viral are eliminated, usually rendering the virus replication deficient, and replaced with a therapeutic cDNA or genomic sequence. The infectious attributes of the virus are retained, thus allowing for entry into the target cell. Either integration of the modified viral genome into the host genome takes place in dividing cell populations or perpetuation of the therapeutic sequences can occur via autosomal replication.
