Targeted Genetics Strengthens Intellectual Property for AAV Vector Manufacturing Processes.

SEATTLE -- Targeted Genetics Corporation (Nasdaq:TGEN) today announced the issuance of an additional patent related to its adeno-associated virus (AAV) vector manufacturing processes. U.S. patent #6,995,006 is titled, "Methods for generating high titer helper-free preparation of released recombinant AAV vectors." The patent describes an AAV manufacturing process in which numerous growth conditions used to culture the production cells are controlled in a manner that leads to the release of AAV vector particles into the cell culture medium without the need for breaking open the host cell membrane. This release of vector into the media leads to improved production quality and allows for a more cost-effective approach to large-scale manufacturing of AAV vectors. Targeted Genetics' growing body of intellectual property related to AAV manufacturing supports several of the Company's product development programs, including its inflammatory arthritis, HIV/AIDS vaccine and congestive heart failure programs.

"The issuance of Targeted Genetics' latest patent further strengthens our leadership position in the field of AAV manufacturing," said Barrie J. Carter, Ph.D., Executive Vice President and Chief Scientific Officer of Targeted Genetics. "This patent covers numerous growth conditions that support the release of AAV vectors into the media. Most AAV harvesting procedures require breaking open the cells in which the vector particles have been produced. This leads to significant levels of contamination, which must then be purified away from the vector particles, requiring an additional and timely step in the manufacturing process. Many of the techniques used to remove these contaminants also trap AAV vector particles, reducing the overall efficiency of the manufacturing process. Under the growth conditions described in this patent, AAV vector particles are released into the cell culture medium in which the producer cells are grown without rupturing the cell membranes. Notably, this release of vector particles allows for vector harvesting procedures that are readily scalable to meet commercial needs, and eliminates contaminants that may occur at significant levels with other vector harvest methods."

The combined attributes of persistent expression and a good safety profile make AAV vectors the vector of choice for developing gene-transfer treatments for a wide variety of chronic disease and the development of viral vaccines. Most AAV production procedures result in AAV vectors being retained inside the producer cells. Under the growth conditions described in this patent, AAV vectors are released from intact cells into the media similarly to the release of recombinant proteins or monoclonal antibodies. Using the growth conditions described in this patent, AAV vectors are harvested from the cell culture supernatant by standard biopharmaceutical methods that are scalable and cost effective. The ability to retain intact cells leads to a harvest that is significantly reduced in contaminants and allows Targeted Genetics to purify AAV vector particles from AAV manufacturing production components by a series of scalable, cost effective chromatography columns. This method can be utilized with any rAAV vector production method including Targeted Genetics' proprietary cell line or hybrid virus technologies, and is expected to support more effective and streamlined production processes.

"Targeted Genetics AAV manufacturing competence continues to fuel our ability to attract strategic partners, enabling us to undertake and aggressively advance our product development efforts in inflammatory arthritis, HIV/AIDS, congestive heart failure and Huntington's disease," said H. Stewart Parker, President and Chief Executive Officer. "Importantly, the methods described in this patent enable manufacturing procedures designed to improve costs, scalability and purification, which are critical for the commercialization of our innovative product pipeline."

About Targeted Genetics

Targeted Genetics Corporation is a biotechnology company committed to the development and commercialization of innovative targeted molecular therapies for the prevention and treatment of inflammatory arthritis, HIV/AIDS and other acquired and inherited diseases with significant unmet medical need. Targeted Genetics uses its considerable knowledge and capabilities in the development and manufacturing of gene delivery technologies to advance a diverse product development pipeline. Its product development efforts target inflammatory arthritis, HIV/AIDS, congestive heart failure, Huntington's disease, and hyperlipidemia. To learn more about Targeted Genetics, visit its website at www.targetedgenetics.com.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995:

This release contains forward-looking statements regarding our intellectual property, research programs and clinical trials, our manufacturing process, and our product development platforms including AAV vectors, our ability to develop and commercialize our product candidates, our ability to attract strategic partners and other statements about our plans, objectives, intentions and expectations. In particular, the statements regarding the Company's pipeline and potential application of this patent to any future product candidates are forward-looking statements. These statements, involve current expectations, forecasts of future events and other statements that are not historical facts. Inaccurate assumptions and known and unknown risks and uncertainties can affect the accuracy of forward-looking statements. Factors that could affect its actual results include, but are not limited to, our ability to obtain, maintain and protect our intellectual property, our ability to raise capital when needed, our ability to recruit and enroll suitable trial participants, the timing, nature and results of research and clinical trials, potential development of alternative technologies or more effective processes by competitors, and, our ability to obtain and maintain regulatory or institutional approvals, as well as other risk factors described in the section entitled "Factors Affecting Our Operating Results, Our Business and Our Stock Price" in Targeted Genetics' Quarterly Report on Form 10-Q for the quarter ended September 30, 2005. You should not rely unduly on these forward-looking statements, which apply only as of the date of this release. We undertake no duty to publicly announce or report revisions to these statements as new information becomes available that may change expectations.