The Lentiviral Vector Reference Working Group (LVRWG) was created at the conclusion of a meeting organized by The Williamsburg BioProcessing Foundation in June 2002, in conjunction with the American Society of Gene Therapy (ASGT) annual conference. The meeting participants were gathered to evaluate the need for developing reference material to ensure comparability of lentiviral and retroviral vectors, in a similar spirit to the Adenovirus Reference Material program that had just been completed. The concensus at the conclusion of this meeting was that the diversity in the lentiviral vector field, which includes vectors derived from different parental viruses and with various designs, does not allow for identification of a single reference material that would benefit more than a single or very few investigators…