ABSTRACT
Non-replication competent retro-vectors capable of introducing foreign DNA were developed in the 1980s, leading to their use in the first human gene therapy trials. In contrast to nonviral transfection methods and non-integrating viruses, retro-vectoring is capable of providing permanent integration and long-term expression. Many gene therapists would prefer to use transfection methods that are safe and efficient, but these provide transient expression as opposed to permanent retroviral integration. Until a synthetic vector can be devised that combines these desirable characteristics, an alternative approach is to improve retroviral delivery by combining it with synthetic, non-recombinogenic vectors and synthetic particle delivery via liposomes. Synthetic vectors were made from the VL30 backbone by means of oligonucleotide-directed gene amplification of the essential cis-acting sequences required to make a vector. In addition to adding to our knowledge of how genes are expressed in different tissues, retrotransposon promoters offer additional choices for transcriptional targeting via retro-vectors.
