Targeted Genetics Corporation announced the issuance of an additional patent related to its adeno-associated virus (AAV) vector construct. U.S. patent #6,596,535 is titled "Metabolically Activated Recombinant Viral Vectors and Methods for Their Preparation and Use."

AAV is a small, single-stranded, stable virus that is not known to cause disease in humans. The naturally occurring form of the virus has only two genes, which are removed in the development of AAV vectors for gene delivery. AAV vectors are thus constructed as delivery vehicles, transferring the gene of interest to the host.

Single stranded DNA vectors like AAV require conversion to a double-stranded DNA form in order for the therapeutic gene of interest to be expressed. The AAV virus DNA is about 4.7 Kb in size. However, a significant number of genes used in gene therapy are approximately half this size (2.5Kb or less). Researchers have generally included stuffer gene sequences along with the gene of interest to fit the full size of the vector. This patent, which is applicable to a number of genes whose DNA is roughly half the size of an AAV payload, is the first to demonstrate that AAV vectors can form intrastrand based pairing, rapidly converting to this expressible form. This results in a more rapid and efficient expression of the therapeutic gene, and has potential for increased benefit when utilized in a gene delivery setting in disease states such as metabolic disorders or protein replacement therapies that utilize genes such as Apo A2, Interferon B and erythropoietin.

Targeted Genetics develops gene therapy products for treating acquired and inherited diseases. The Company has a lead clinical product development program targeting cystic fibrosis and a promising pipeline of product candidates focused on arthritis, an AIDS vaccine, hemophilia and cancer. The Company has a broad platform of gene delivery technologies, as well as a promising body of technology for cellular therapy.