Document Type: Narrative Review
Department of Biology, Faculty of Basic Science, Shahed University, Tehran, Iran
Green Gene Company, Tehran, Iran
Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
In general, gene therapy is the transfer of a genetic material to treat a disease, or at least to improve the clinical status of a patient. One way gene therapy works is to turn viruses into genetic vectors that carry the gene of interest to the target cells. Based on the genome’s nature, these vectors are divided into RNA-based or DNA-based viral vectors. Most RNA-based vectors are derived from simple retroviruses, such as the murine leukemia virus. One major drawback of these viruses is that they are not transferred to non-dividing cells (post-mitotic cells). This problem can be solved by using new retroviral vectors derived from lentiviruses, such as the human immunodeficiency virus (HIV). DNA-based vectors originate from adeno-viruses and adeno-associated viruses (AAVs). An example of gene deletion due to gene therapy is the deletion of the human CCR5 gene in T cells (which control HIV infection). Although available vector systems have the ability to transfer genes to living cells (in the human body), an ideal vector for gene delivery has not yet been found. Therefore, the current viral vectors should be used with great caution in human cases. Moreover, the development of new vectors is necessary.