Recombinant adeno-associated viral (rAAV) vectors are known to be efficient vehicles for gene transfer in animal models. The attractive feature of this vector system consists primarily of long-term gene expression with little or no associated toxicities following administration to a variety of tissues. Previous and ongoing clinical trials in humans demonstrate a very good overall safety profile, but problems persist due to the lack of any systematic method for normalizing doses administered to animals and humans. To date, most of the work involves AAV serotype 2 vectors, but vector systems based on other AAV serotypes continue to develop rapidly. Administered doses are usually based on titer, but the defective nature of AAV makes determining vector infectious units difficult. Titering methods based on vector genomes (using hybridization, real-time PCR, or spectrophotometry) are more reliable, but give no information as to the infectivity of the vector. Determining infectious titer is critical, as the ratio of infectious virions to vector genome-containing virions helps to determine the dose, potency, and strength of the vector preparation…
Category: <span>Viral Vectors</span>
The development of reference testing reagents has been used successfully in the past to standardize measurements among laboratories, particularly for biological products such as recombinant cytokines. This approach was recommended by many parties with a stake in adenovirus vector delivery in order to address the fact that particle units and infectious units are not standardized in the field. This has made interpretation of preclinical and clinical data, as it relates to the amount of adenovirus vector administered, difficult to compare across the field. An Adenovirus Reference Material is being developed to define the particle unit and infectious unit for adenovirus gene vectors, and create a commonality for comparisons, especially for data related to vector safety…
Introgen Therapeutics has been producing clinical-grade adenoviral vectors in scaled-up processes, in cGMP facilities, for over five years. Semi-automated hand filling, using a Watson-Marlow 505Di/L pump, has been used over this period to fill batch sizes of up to 2 liters of adenovirus. While this procedure has been robust and demonstrated a high level of sterility assurance through regularly scheduled media fill studies and product testing, the firm needed to move to the next level of fill sizes. Anticipating up to 10,000 fills in 3 mL vials, Introgen has worked in collaboration with M&O Perry Corp. to develop an automated fill capability that utilizes the same base procedure but in an automated fashion…
A formulation for purified adenoviral vectors was developed that provides stability through freeze-thaw stress and long-term storage at non-frozen temperatures. To evaluate the various test conditions, a panel of stability indicating methods was assembled, which included laser light scattering, HPLC, and transgene expression assays. Preformulation studies were conducted, and the effects of buffer species, pH, cryoprotectants, and salts upon adenoviral vector stability were determined…