Choice and Manipulation of Retroviral Vectors

During the past few years, retroviral vectors have become a very important and widely used means of gene transfer. In the laboratory, their use has expanded the capabilities of investigators to perform important experiments that have solved previously unanswerable biological questions. Retroviral vectors exploit the inherent capacity of retrovkuses to transfer genetic material stably into a cell’s genome and subsequently express it in a manner that is generally not detrimental to the host-cell. Initial entry of genetic material into cells via retroviral vectors is so efficient that it permits successful transfer of genes into limiting numbers of cells, such as hematopoietic stem cells in explanted bone marrow, and transfer approaching 100% in tissue-culture experiments. In comparison, chemical and electrical means of gene transfer require large initial numbers of cells and, under optimal circumstances, function at efficiencies several orders of magnitude lower than retroviral vectors, and only in a limited number of specific cell types.