Adeno-associated Virus Reference Standard

An increasing number of groups have been able to generate in vivo data using recombinant adeno-associated viral (rAAV) vectors now that vector stocks of reasonable titer and purity are available. The results of these studies have been nothing less than phenomenal, showing efficient and long-term expression of rAAV vectors with few adverse effects, and immune responses that have been quite modest. Understandably, there has been a move toward a greater number of clinical trials of rAAV, particularly for application to genetic and metabolic disorders, in which long-term expression of the transgene is usually the primary goal. A number of investigators and members of the regulatory community have recognized the potential of rAAV for gene therapy and the pivotal role being played by academic centers and small biotechnology companies in its development. It is evident that a fairly large amount of preclinical data might be available from ongoing experiments being performed in rAAV laboratories. However, in order to share such preclinical data in a meaningful way, it would be useful if a single reference standard stock (RSS) with a defined titer was available to all centers. This RSS would serve as an index for comparison of titer values between centers using different assays, therefore, it is essential that it is well characterized. Furthermore, the methods used to determine titer and other characteristics should be well defined and able to be performed reproducibly and independent of laboratory locale.

Funding for the NGVL was instrumental in establishing this project. The AAV Reference Standard Working Group was formed to produce and characterize an AAV2-GFP vector. The volunteer Working Group consists of 15 academic and industry laboratories from the United States, France, and Japan. Production and purification of the reference standard started in March 2006 at the University of Florida's Powell Gene Therapy Center Vector Core and was completed in January 2007. Approximately 150ml of AAV2-GFP = 5.69X10e14vg (= 3.79X10e12vg/ml) was made. We are working with Introgen, Inc. to finalize the details for the vector fill. Once finalized, the vector will be diluted to the proper concentration (2X10e11vg/ml) divided into 2 or 3 portions and filled at 0.5ml in vials = ~5700 vials, and then frozen. The vials will be sent for repository at ATCC. Characterization of the Reference Standard by several laboratories began in Q2 of 2007, followed by statistical analysis. The Reference Standard is now available through the ATCC - www.atcc.org.

For Further information, please contact
Richard O. Snyder, Ph.D.
PO Box 110585
University of Florida
Gainesville, FL 32611-0585
Tel: 386-418-1642
Fax: 386-462-7365
e-mail: rsnyder at cerhb dot ufl dot edu