Beyond retrovirus infection: HIV meets gene therapy

The human immunodeficiency virus (HIV) is classified as a retrovirus because of its RNA genome and the fact that it requires reverse transcriptase to convert it into DNA. This virus belongs to the lentivirinae subfamily and is able to infect quiescent cells but is better known for its association with acquired immunodeficiency syndrome (AIDS) and can be described as one of the most effective vectors for gene transfer. Biosafety concerns are present whenever viral vectors are employed but are particularly pertinent to the development of HIV-based vectors. Insertional mutagenesis and the production of new replication-competent viruses (RCV) have been pointed to as major problems, but experimental data have shown that safe protocols can be developed for their production and application. Virological, evolutionary, immunological and cell biology studies must be conducted jointly to allow the clinical use of HIV vectors. This review will focus on the general properties, production and applications of retrovectors in gene therapy, with particular emphasis on those based on HIV systems.