Author's Note

Abstract

This mini-review was initially written in 2002 as an institutional training document and was subsequently distributed to interested individuals on the Biosafety Discussion List (BIOSAFTY@mitvma.mit. edu). Two events prompted its updating and publication for a wider audience. First, there were two cases of leukemia associated with retroviral-mediated gene therapy in children with severe combined immune deficiency, which have resulted in a cessation of gene therapy trials in the United States and Europe. Secondly , we have continued to receive requests for this review, and it has resurfaced from secondary sources, so we were pleased to respond to Karen Byers' request to submit the review to Applied Biosafety. Finally , we continue to encounter researchers who assume that retrovirus vectors must be safe because they are just little pieces of nucleic acid that you can buy from commercial vendors. Abstract Retroviral vectors are becoming standard tools in cell biology as well as potential therapeutic agents for human disease. Many investigators have come to believe that retroviral vectors are safe, but both current biosafety guidelines and distributors of vectors recommend using the vectors under Biosafety level-2 (BSL-2) containment, with certain experiments requiring BSL-3 practices. This short review considers the dangers posed by the large variety of retroviral vectors and gives the rationale for safety evaluation.